tag:theconversation.com,2011:/fr/topics/tropics-8458/articlesTropics – The Conversation2024-03-09T08:43:31Ztag:theconversation.com,2011:article/2253482024-03-09T08:43:31Z2024-03-09T08:43:31ZThe Great Barrier Reef’s latest bout of bleaching is the fifth in eight summers – the corals now have almost no reprieve<p>For the fifth time in just the past eight summers – 2016, 2017, 2020, 2022 and now 2024 - huge swathes of the Great Barrier Reef are experiencing extreme heat stress that has triggered yet another <a href="https://www2.gbrmpa.gov.au/learn/reef-health/reef-health-updates">episode of mass coral bleaching</a>. </p>
<p>Including two earlier heating episodes – in 1998 (which was at the time the hottest year globally on record) and 2002 – this brings the tally to seven such extreme events in the past 26 years. </p>
<p>The most conspicuous impact of unusually high temperatures on tropical and subtropical reefs is wide-scale coral bleaching and death. Sharp spikes in temperature can destroy coral tissue directly even before bleaching unfolds. Consequently, if temperatures exceed 2°C above the normal summer maximum, heat-sensitive corals die very quickly. </p>
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<figcaption><span class="caption">Reef Health Update (8 March 2024) Great Barrier Reef Marine Park Authority.</span></figcaption>
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<h2>What is coral bleaching?</h2>
<p>Bleaching happens when marine heatwaves disrupt the relationship between corals and their “photosynthetic symbionts” – tiny organisms that live inside the corals’ tissues and help power their metabolism.</p>
<p>Severe bleaching is often fatal, whereas corals that are mildly bleached can slowly regain their symbionts and normal colour after the end of summer, and survive. </p>
<p>Before 1998, coral bleaching on the Great Barrier Reef was infrequent and localised. But over the past four decades, bleaching has increased in frequency, severity and sptial scale, as a result of <a href="https://www.science.org/doi/10.1126/science.aan8048">human-induced climate heating</a>.</p>
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Read more:
<a href="https://theconversation.com/we-just-spent-two-weeks-surveying-the-great-barrier-reef-what-we-saw-was-an-utter-tragedy-135197">We just spent two weeks surveying the Great Barrier Reef. What we saw was an utter tragedy</a>
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<p>“Mass coral bleaching” refers to bleaching that is severe and widespread, affecting reefs at a regional scale or even throughout the tropics triggered by rising global sea temperatures.</p>
<p>The Great Barrier Reef consists of more than 3,000 individual coral reefs. It’s the same size as Japan or Italy, and extends for 2,300km along the coast of Queensland. Widespread coral deaths during extreme heatwaves, affecting hundreds of millions of coral colonies, <a href="https://onlinelibrary.wiley.com/doi/10.1111/gcb.15805">far exceed the damage</a> typically caused by a severe cyclone.</p>
<h2>How bad is 2024?</h2>
<p>Heat stress this week is reaching record levels on large parts of the Great Barrier Reef. </p>
<p>Climate scientists can measure the accumulation of heat stress throughout the summer by using a metric called “<a href="https://www.pacioos.hawaii.edu/voyager/info/coral_bleaching_degree_heating_week.html">degree heating weeks</a>” (DHW), which factors in both the duration and intensity of extreme heat exposure. This measures how far the temperature is above the threshold that triggers mild bleaching (1°C hotter than the normal summer maximum), and how long it stays above that threshold.</p>
<p>The same DHW exposure can result either from a long, moderate heatwave or from a short, intense peak in temperatures. The 2023–24 summer has been a slow burner on the Great Barrier Reef – sea temperatures have not been as extreme as during previous bleaching events, but they have <a href="http://www.bom.gov.au/oceanography/oceantemp/sst-outlook-map.shtml">persisted for longer</a>.</p>
<p>As a general rule of thumb, 2–4 DHW units can trigger the onset of bleaching, and heat-sensitive species of coral begin to die at 6–8 DHW units. So far this summer, <a href="https://x.com/profterryhughes/status/1762293105175445921?s=12&t=jfoU3j0RiQtYeeHqbSpjlA">according to the US National Oceanographic and Atmospheric Administration</a>, heat stress on the Great Barrier Reef has climbed to 10–12 DHW units on many individual reefs, and has been north and south compared to the central region. Heat stress will likely peak in the next week or two at levels above all previous mass bleaching and mortality events since 1998, before falling as temperatures drop.</p>
<p>Coral bleaching is typically very patchy at the enormous scale of the Great Barrier Reef. In each of the previous events since 1998, <a href="https://www.cell.com/current-biology/pdfExtended/S0960-9822(21)01490-1">20–55% of individual reefs</a> experienced severe bleaching and coral deaths, whereas 14–48% of reefs were unharmed.</p>
<p>Given the near-record levels of heat stress this summer, we can expect heavy losses of corals to occur on hundreds of individual reefs over the next few months.</p>
<h2>What’s the longer-term outlook?</h2>
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<p>This latest, still-unfolding event was entirely predictable, as ocean temperatures continue to rise due to global heating. </p>
<p>Three of the seven mass bleaching events so far on the Great Barrier Reef coincided with El Niño conditions (1998, 2016 and this summer), and the remaining four did not. Increasingly, climate-driven coral bleaching and death is happening regardless of whether we are in an El Niño or La Niña phase. Average tropical sea surface temperatures are <a href="https://www.science.org/doi/10.1126/science.aan8048">already warmer today</a> under La Niña conditions than they were during El Niño events only three or four decades ago.</p>
<p>The Great Barrier Reef is now a chequerboard of reefs with different recent histories of coral bleaching. Reefs that bleached in 2017 or 2016 have had only five or six years to recover before being hit again this summer – assuming they escaped bleaching during the 2020 and 2022 episodes. </p>
<p>Clearly, the gap between consecutive heat extremes is shrinking – we are vanishingly unlikely to see another 14-year reprieve like 2002 to 2016 again in our lifetimes, until global temperatures stabilise.</p>
<p>Ironically, the corals that are now prevalent on many reefs are young colonies of fast-growing, heat-sensitive species of branching and table-shaped corals – analogous to the rapid recovery of flammable grasses after a forest fire. These species can restore coral cover quickly, but they also make the Great Barrier Reef more vulnerable to future heatwaves. </p>
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Read more:
<a href="https://theconversation.com/concern-for-the-great-barrier-reef-can-inspire-climate-action-but-the-way-we-talk-about-it-matters-216992">Concern for the Great Barrier Reef can inspire climate action - but the way we talk about it matters</a>
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<p>Attempts to restore depleted coral cover through coral gardening, assisted migration (by harvesting larvae) and assisted evolution (rearing corals in an aquarium) are prohibitively expensive and <a href="https://www.cell.com/one-earth/pdf/S2590-3322(23)00189-6.pdf">unworkable at any meaningful scale</a>. In Florida, coral nurseries <a href="https://thehill.com/homenews/ap/ap-u-s-news/ap-hot-seawater-killed-most-of-cultivated-coral-in-florida-keys-in-setback-for-restoration-effort/">suffered mass deaths</a> due to record sea temperatures last summer.</p>
<p>The only long-term way to protect corals on the Great Barrier Reef and elsewhere is to rapidly reduce global greenhouse emissions.</p><img src="https://counter.theconversation.com/content/225348/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Terry Hughes does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>The Great Barrier Reef is facing its worst summer of sustained heat stress since the mass bleaching event of 1998, but now with less time to recover amid repeated brutal conditions.Terry Hughes, Distinguished Professor, James Cook UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2219882024-03-05T19:10:34Z2024-03-05T19:10:34ZEver heard of the Maritime Continent? It’s not far from Australia – and channels heat around the world<figure><img src="https://images.theconversation.com/files/579775/original/file-20240305-18-yv55d.jpg?ixlib=rb-1.1.0&rect=0%2C24%2C5004%2C3617&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/azure-beach-rocky-mountains-clear-water-670788406">Cocos.Bounty/Shutterstock</a></span></figcaption></figure><p>Africa, Asia, Australia, Antarctica, North and South America, Europe – and the <a href="http://www.bom.gov.au/climate/about/tropics/maritime-continent.shtml">Maritime Continent</a>. </p>
<p>Never heard of the last one? That’s because it’s not a continent made of land. In fact, it’s the largest warm tropical sea in the world, lapping against the shores of Indonesia, Malaysia, Papua New Guinea, the Philippines and smaller countries. </p>
<p>Why call it a continent? The name comes from the way the seas and land in this region interact. This single region is the main heat engine pushing heat around the world. The Maritime Continent is home to large expanses of warm, shallow seas bigger than Australia. Known as the tropical warm pool, these seas – the warmest on Earth – sustain warm sea temperatures and act as a engine for the Earth’s climate system. </p>
<p>As the world heats up under climate change, more heat pours into the seas. That means the Maritime Continent’s warm pool is growing. It’s <a href="https://www.nature.com/articles/s41586-019-1764-4">roughly doubled</a> from 22 million (1900-1980) to 40 million square kilometres (1981-2018).</p>
<h2>Why is this area special?</h2>
<p>Start with the sun. The midday sun is mostly directly overhead in the tropics. Incoming radiation from the sun is at its peak along the equator, which bisects Indonesia. In this region, the seas are relatively shallow – the Java Sea, for instance, averages a depth of just 46 metres. Sunlight can penetrate to the seabed and so shallow water depths allow for more efficient heating of the water. As a result, the surface temperatures of this enormous warm pool of water are over 28°C.</p>
<p>Then there’s the wind. The prevailing winds here are the southeasterly trade winds, which blow along the surface of the Pacific near the equator. As they blow, they push the water below, pooling warm water in the western Pacific and around the islands of the Maritime Continent. These waters are usually the warmest oceans in the world. </p>
<p>Heat is energy, and energy makes things happen. Some of the heat leaves the seas and enters the atmosphere in a process known as convection. As the Earth rotates, the rising hot air spins away from the equator towards the poles. In this way, it spreads heat around the planet. The heat also drives evaporation, leading to high humidity rates and making the region climatically unstable. Intense storms driven by convection – rising hot air from the seas – can form at any time of the year. </p>
<p>Land heats and cools faster than water. As the land surface heats up, it can drive the development of convective storms on a near daily basis in some places. Other large storms can form as warm, moist air is blown over terrain and pushed upwards when it hits mountains. </p>
<p>This potent combination of heat, moisture and wind act to transfer huge amounts of heat to the upper reaches of the atmosphere, which then spreads around the world. </p>
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<a href="https://images.theconversation.com/files/579776/original/file-20240305-24-q8xvjk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="thousand islands java sea" src="https://images.theconversation.com/files/579776/original/file-20240305-24-q8xvjk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/579776/original/file-20240305-24-q8xvjk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/579776/original/file-20240305-24-q8xvjk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/579776/original/file-20240305-24-q8xvjk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/579776/original/file-20240305-24-q8xvjk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/579776/original/file-20240305-24-q8xvjk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/579776/original/file-20240305-24-q8xvjk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">The Java Sea is shallow – and very warm.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/thousand-islands-java-indonesia-1486311842">Bryce P/Shutterstock</a></span>
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<h2>Keeping a lid on it</h2>
<p>You might not know it, but the atmosphere has a lid of sorts. You and I spend our lives in the troposphere, the lowest part of the atmosphere where ground and air meet. Here, the temperature generally falls as you get higher, which is why mountains are colder. In the stratosphere, by contrast, the air usually gets warmer with height.</p>
<p>Between the troposphere and the stratosphere lies the tropopause. This “lid” acts to keep most clouds and rain closer to Earth. </p>
<p>In Melbourne, the tropopause is about 11km above the city. But the warm, expanding atmosphere of the Maritime Continent pushes the tropopause as high as 18km above the surface. </p>
<p>This means there’s more space for heated and unstable air to rise and give birth to huge and seriously energetic cumulonimbus stormclouds. From here, heat is diverted towards the poles in global air circulation currents within the troposphere. </p>
<p>But when you’re at sea level in the Maritime Continent, you can have a totally different experience. Because so much of the heat rises, low atmospheric pressure develops and the equatorial winds at the surface can be very calm. In the age of sail, sailors called these conditions “the doldrums”. </p>
<p>Australia’s Bureau of Meteorology pays close attention to the Maritime Continent, because it has great influence over our weather – and not just for the tropical north.</p>
<p>When sea surface temperatures change up here, we know changes are coming to Australia’s weather patterns. Like India, northern Australia is monsoonal. Little rain falls during the dry season, April to October. When the wind patterns change in tropical Australia and freshening westerlies converge with the trade winds very late in the year, the monsoon arrives, bringing torrential rain.</p>
<p>It’s not just the north – temperature changes in the tropical warm pool can influence atmospheric pressure systems and drive changes in weather patterns in southern Australia too.</p>
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Read more:
<a href="https://theconversation.com/as-seas-get-warmer-tropical-species-are-moving-further-from-the-equator-218676">As seas get warmer, tropical species are moving further from the equator</a>
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<h2>What does the future hold?</h2>
<p>The Maritime Continent is a weather engine, concentrating heat in warm seas and spreading it around the world. </p>
<p>In recent months, sea surface temperatures around the world are higher than ever recorded, and getting higher still. What will happen to it as more trapped heat pours into the oceans? </p>
<p>Certainly, the warm pool of water unpinning the Maritime Continent will <a href="https://www.climate.gov/news-features/featured-images/warm-pool-indo-pacific-ocean-has-almost-doubled-size-changing-global">keep expanding</a>, as it has for decades. What that means for us isn’t as clear. </p>
<p>We don’t know yet whether a bigger tropical warm pool will allow more tropical cyclones to develop, or whether it will change <a href="https://www.nature.com/articles/s41586-019-1764-4">how intense</a> the monsoon will be. </p>
<p>Some research suggests higher sea temperatures can actually dampen down the formation of clouds from convection, which could mean <a href="https://geoscienceletters.springeropen.com/articles/10.1186/s40562-016-0054-3">regional droughts</a> for countries of the Maritime Continent. </p>
<p>To help find out, I helped other researchers operate an instrument-packed aircraft which flew many measurement missions from Cairns earlier this year, including <a href="https://www.cqu.edu.au/news/1111372/scientific-jet-measures-atmospheric-chemistry">heading for the seas</a> of the Maritime Continent. We measured concentrations of atmospheric molecules. The data we gathered will, we hope, help weather modellers better gauge what hotter tropical seas mean for the world. </p>
<p>This uncertainty means the Maritime Continent is worth watching. </p>
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Read more:
<a href="https://theconversation.com/why-predicting-the-weather-and-climate-is-even-harder-for-australias-rainy-northern-neighbours-106939">Why predicting the weather and climate is even harder for Australia’s rainy northern neighbours</a>
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<img src="https://counter.theconversation.com/content/221988/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Michael Hewson does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Is there really a secret continent to Australia’s north? Not quite. The Maritime Continent is a region where hot seas and islands shape the world’s climate.Michael Hewson, Senior Lecturer Geography, CQUniversity AustraliaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2143462024-02-15T22:55:49Z2024-02-15T22:55:49Z20°C seems the optimal temperature for life on Earth to thrive – what does this mean in a warming world?<p>Have you ever wondered about the optimal temperature for life on Earth? For humans, 20°C is comfortable. Any warmer and we <a href="https://www.nature.com/articles/nature15725">work less efficiently</a> because releasing heat requires energy.</p>
<p>We know many species can live at much colder or warmer temperatures than humans. But our <a href="https://escholarship.org/uc/item/3mr1d0z4">systematic review</a> of published research found the thermal ranges of animals, plants and microbes living in air and water overlap at 20°C. Could this be a coincidence?</p>
<p>For all species, the relationship with temperature is an asymmetric bell-shaped curve. This means biological processes <a href="https://www.sciencedirect.com/science/article/abs/pii/S0956713512003210">increase in line with temperature</a>, reach a maximum, and then rapidly decline when it gets too hot. </p>
<p>Recently, a New Zealand research group noticed the number of marine species <a href="https://www.pnas.org/doi/abs/10.1073/pnas.2015094118">did not peak at the equator</a>, as has been commonly assumed. Rather, the number dipped, with peaks in the subtropics. </p>
<p>Follow-up <a href="https://www.pnas.org/doi/abs/10.1073/pnas.1916923117">studies</a> showed this dip has been getting deeper since the last ice age about 20,000 years ago. And it has been deepening faster due to global ocean warming. </p>
<p>When the number of species was plotted against the average annual temperature, there was a decline above 20°C. A second coincidence?</p>
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Read more:
<a href="https://theconversation.com/remote-pacific-coral-reef-shows-at-least-some-ability-to-cope-with-ocean-warming-new-study-211852">Remote Pacific coral reef shows at least some ability to cope with ocean warming – new study</a>
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<h2>Biological processes and biodiversity</h2>
<p>Research in Tasmania <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0153343">modelled the growth rates</a> of microbes and multi-cellular organisms and found the most stable temperature for their biological processes was also 20°C. </p>
<p>This “Corkrey model” built on <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/ecog.01948">other studies</a> showing 20°C was the most stable temperature for biological molecules. A third coincidence?</p>
<p>We teamed up with colleagues from Canada, Scotland, Germany, Hong Kong and Taiwan to search for general patterns in how temperature affects life. To our surprise, everywhere we looked we kept finding that, indeed, 20°C is a pivotal temperature for many measures of biodiversity, and not only for marine species. </p>
<p>Examples show temperatures warmer than around 20°C result in decreases in various crucial measures: </p>
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<li><p>marine and freshwater species’ tolerance of low oxygen</p></li>
<li><p>marine pelagic (open water living) and benthic (seabed living) algal productivity and fish predation rates on bait</p></li>
<li><p>global species richness in pelagic fishes, plankton, benthic invertebrates and fossil molluscs</p></li>
<li><p>and genetic diversity. </p></li>
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<p>There were also increased extinctions in the fossil record when temperatures exceeded 20°C.</p>
<h2>Increased species richness</h2>
<p>Globally, the range of temperatures that reef fishes and invertebrates live at is narrowest among species whose geographic distributions centred on 20°C. The same effect is seen in microbes.</p>
<p>While many species have evolved to live at warmer and colder temperatures, most species live at 20°C. Also, extinctions in the fossil record – including sponges, lamp shells, molluscs, sea mats (<a href="https://www.sciencelearn.org.nz/resources/147-bryozoans">bryozoans</a>), starfish and sea urchins, worms and crustaceans – were lower at 20°C.</p>
<p>As species evolve to live at temperatures above and below 20°C, their thermal niche gets wider. This means most can still live at 20°C even if they inhabit hotter or colder places.</p>
<p>The mathematical Corkrey model predicts that thermal breadth should be minimised, and biological processes most stable and efficient, at 20°C. In turn, this should maximise species richness across all domains of life, from bacteria to the multi-cellular plants and animals. The model therefore provides a theoretical explanation for this “20°C effect”.</p>
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Read more:
<a href="https://theconversation.com/marine-life-is-fleeing-the-equator-to-cooler-waters-history-tells-us-this-could-trigger-a-mass-extinction-event-158424">Marine life is fleeing the equator to cooler waters. History tells us this could trigger a mass extinction event</a>
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<h2>Predicting the effects of climate change</h2>
<p>That life seems centred around 20°C implies fundamental constraints that compromise the ability of tropical species to adapt to higher temperatures. </p>
<p>As long as species can shift their ranges to adapt to global warming, the 20°C effect means there will be local increases in species richness up to an annual average of 20°C. Above that, richness will decline. </p>
<p>This means the many marine species that can adapt to global warming by shifting their geographic distribution are unlikely to go extinct due to climate change. </p>
<p>However, land species may not be able to shift their geographic distributions so easily due to landscapes modified by cities, farming and other human infrastructures.</p>
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Read more:
<a href="https://theconversation.com/warming-oceans-may-force-new-zealands-sperm-and-blue-whales-to-shift-to-cooler-southern-waters-188522">Warming oceans may force New Zealand's sperm and blue whales to shift to cooler southern waters</a>
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<p>The 20°C effect is the simplest explanation for the above phenomena, including: trends in species richness and genetic diversity with temperature; extinction rates in the fossil record; biological productivity; optimal growth rate; and marine predation rates. </p>
<p>Despite the complexity of multi-cellular species, it is remarkable that the cellular-level temperature efficiencies are reflected in those other aspects of biodiversity.</p>
<p>Exactly why 20°C is pivotal and energy-efficient for cellular processes may be due to the molecular properties of water associated with cells. These properties may also be why ~42°C seems an absolute limit for most species. </p>
<p>A greater awareness of this 20°C effect may lead to new insights into how temperature controls ecosystem processes, species abundance and distribution, and the evolution of life.</p><img src="https://counter.theconversation.com/content/214346/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Mark John Costello received funding from the Royal Society of New Zealand-Te Apārangi that contributed to this research.. </span></em></p><p class="fine-print"><em><span>Ross Corkrey does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>The ‘20°C effect’ could give us new insights into how temperature controls ecosystems and influences evolution – as well as how species might adapt to climate change.Mark John Costello, Professor, Faculty of Biosciences and Aquaculture, Nord UniversityRoss Corkrey, Adjunct Senior Researcher in Biostatistics, University of TasmaniaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2213132024-01-19T21:07:32Z2024-01-19T21:07:32Z1 billion people left dangerously exposed to heat stress by gaps in climate monitoring<figure><img src="https://images.theconversation.com/files/570270/original/file-20240119-19-y6h5wq.jpg?ixlib=rb-1.1.0&rect=0%2C11%2C7360%2C4891&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/ghaziabad-uttar-pradesh-india-may-12-2170143881">PradeepGaurs/Shutterstock</a></span></figcaption></figure><p>2023 was the <a href="https://wmo.int/media/news/wmo-confirms-2023-smashes-global-temperature-record">hottest year on record</a>. <a href="https://www.weforum.org/agenda/2020/12/climate-change-humidity-paradox/">Humidity is rising too</a>. Heat and humidity are a dangerous combination, threatening all aspects of our lives and livelihoods.</p>
<p>Climate change is pushing humid heat dangerously close to the <a href="https://iopscience.iop.org/article/10.1088/1748-9326/ac71b9">upper limits of what people can survive</a>. Parts of the world are <a href="https://doi.org/10.1126/sciadv.adg9297">on track</a> for conditions beyond the limits of human tolerance.</p>
<p>Yet <a href="https://doi.org/10.1016/j.oneear.2023.12.005">our new research</a> shows poor weather station coverage across the tropics leads to underestimates of heat stress in cities. This means global climate change assessments probably overlook the local impacts on people.</p>
<p>Concentrated across tropical Asia and Africa, informal settlements, commonly known as “slums”, are on the <a href="https://unhabitat.org/pro-poor-climate-action-in-informal-settlement">front line of climate exposure</a>. The shortfalls in climate monitoring leave these communities dangerously vulnerable to rising humid heat. With few options to adapt, millions could be forced to seek refuge away from the hottest parts of the tropics.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/570282/original/file-20240119-15-ptsagy.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="World map showing percentage of population living in informal settlements by country, with dots indicating weather station sites" src="https://images.theconversation.com/files/570282/original/file-20240119-15-ptsagy.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/570282/original/file-20240119-15-ptsagy.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=355&fit=crop&dpr=1 600w, https://images.theconversation.com/files/570282/original/file-20240119-15-ptsagy.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=355&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/570282/original/file-20240119-15-ptsagy.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=355&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/570282/original/file-20240119-15-ptsagy.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=446&fit=crop&dpr=1 754w, https://images.theconversation.com/files/570282/original/file-20240119-15-ptsagy.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=446&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/570282/original/file-20240119-15-ptsagy.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=446&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A map showing percentage of population living in informal settlements by country. Dots indicate weather station sites.</span>
<span class="attribution"><span class="source">Emma Ramsay</span></span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/global-warming-now-pushing-heat-into-territory-humans-cannot-tolerate-138343">Global warming now pushing heat into territory humans cannot tolerate</a>
</strong>
</em>
</p>
<hr>
<h2>Why is heat such a threat in these places?</h2>
<p><a href="https://population.un.org/wup/publications/Files/WUP2018-PopFacts_2018-1.pdf">Rapid urbanisation</a> that outpaces planned, formal development is driving the growth of informal settlements. Their residents usually lack infrastructure and services, such as electricity and water supply, that many city dwellers take for granted. </p>
<p>More than <a href="https://unstats.un.org/sdgs/report/2019/goal-11/">1 billion people live in informal settlements</a>. The United Nations expects this number to grow to <a href="https://unstats.un.org/sdgs/report/2023/The-Sustainable-Development-Goals-Report-2023.pdf">3 billion over the next 30 years</a>. In countries such as Kenya or Bangladesh, nearly half the urban populations lives in informal settlements.</p>
<p>Most informal settlements are located in the tropics. Here it is hot and humid year-round, but their residents have few options to adapt to heat stress. </p>
<p>Most households in these settlements are on low incomes. Many residents <a href="https://doi.org/10.1016/j.uclim.2022.101401">must work outdoors</a> for their livelihoods, which exposes them to heat and humidity. </p>
<p>On top of this, because informal settlements fall outside official systems and regulations, we often lack data about the threats they face.</p>
<figure class="align-center ">
<img alt="A farmer works in a rice field next to an informal settlement" src="https://images.theconversation.com/files/570004/original/file-20240118-19-m8smxw.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/570004/original/file-20240118-19-m8smxw.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/570004/original/file-20240118-19-m8smxw.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/570004/original/file-20240118-19-m8smxw.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/570004/original/file-20240118-19-m8smxw.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/570004/original/file-20240118-19-m8smxw.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/570004/original/file-20240118-19-m8smxw.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">People who must work outdoors to make a living, such as many residents of this settlement in Makassar, Indonesia, are highly exposed to heat.</span>
<span class="attribution"><span class="source">Revitalising Informal Settlements and their Environments, Monash University</span></span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/urban-growth-heat-islands-humidity-climate-change-the-costs-multiply-in-tropical-cities-120825">Urban growth, heat islands, humidity, climate change: the costs multiply in tropical cities</a>
</strong>
</em>
</p>
<hr>
<h2>What’s missing from climate data?</h2>
<p>Most of the world’s population <a href="https://doi.org/10.1088/1748-9326/ac30c0">lives more than 25km from a weather station</a>. This means weather stations rarely capture the full range of temperature and humidity in cities, which are usually hotter than non-urban surrounds – the <a href="https://www.australianenvironmentaleducation.com.au/climate-change/urban-heat-island-effect/">urban heat island effect</a>. These gaps in monitoring are largest across the tropics where most informal settlements are located.</p>
<p>As individuals we experience heat on a local scale, which isn’t captured by sparse weather station networks or meteorological models. If your home is too hot, a weather report telling you otherwise offers little respite. </p>
<p><a href="https://doi.org/10.1016/j.oneear.2023.12.005">Our research</a> compiled local climate monitoring data from informal settlements in seven tropical countries. We compared these data to temperature and humidity measurements at the nearest weather station.</p>
<p>We found weather stations severely underestimate the heat stress that people experience in their homes and local communities. This means global climate assessments and projections also likely underestimate local-scale impacts. </p>
<p>Although these data come from a relatively small number of studies, they highlight a major hurdle for climate adaptation. Without accurate heat stress data, how can we ensure the most vulnerable communities are not left behind?</p>
<figure class="align-center ">
<img alt="Looking along a water channel towards an informal settlement in Makassar, Indonesia" src="https://images.theconversation.com/files/570005/original/file-20240118-15-u3alzk.jpeg?ixlib=rb-1.1.0&rect=0%2C0%2C2835%2C1897&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/570005/original/file-20240118-15-u3alzk.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/570005/original/file-20240118-15-u3alzk.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/570005/original/file-20240118-15-u3alzk.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/570005/original/file-20240118-15-u3alzk.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=565&fit=crop&dpr=1 754w, https://images.theconversation.com/files/570005/original/file-20240118-15-u3alzk.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=565&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/570005/original/file-20240118-15-u3alzk.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=565&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Lack of accurate local data means climate adaptation efforts could overlook communities exposed to extreme heat and humidity.</span>
<span class="attribution"><span class="source">Grant Duffy, Revitalising Informal Settlements and their Environments, Monash University</span></span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/why-40-c-is-bearable-in-a-desert-but-lethal-in-the-tropics-206237">Why 40°C is bearable in a desert but lethal in the tropics</a>
</strong>
</em>
</p>
<hr>
<h2>Even if they get a heat warning, options are limited</h2>
<p>During a heatwave in Australia we are usually told to <a href="https://www.redcross.org.au/heatwaves/#:%7E:text=non%2Dperishable%20foods.-,During%20a%20heatwave,you%20don't%20feel%20thirsty.">stay inside and drink lots of water</a>. For residents of an informal settlement, this advice might actually increase their risk of health impacts.</p>
<p>Heat can be even <a href="https://doi.org/10.1016/j.isci.2021.103248">worse indoors in informal housing</a> with poor ventilation and insulation. Very few households have air conditioning (or could afford to run it if they did). Residents might not have access to safe drinking water, adding to the health risks of heat stress.</p>
<p>What’s more, advice and alerts are unlikely even to reach informal settlements. A <a href="https://www.undrr.org/media/91954/download?startDownload=true">2023 World Meteorological Organisation report</a> found only half of the world’s countries have early-warning systems. </p>
<p>These systems are activated if forecast heat is above certain trigger levels. Health advice and alerts to the public can be backed by extra public health measures. <a href="https://www.icpac.net/">Regional climate centres</a> currently issue broad-scale alerts, but forecasts and responses need to operate at smaller scales to be effective.</p>
<p>And, as we have shown, forecasts are based on weather station data that underestimate heat in informal settlements. This means early-warning systems could fail to activate even though residents of these settlements will experience dangerous heat stress.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/climate-explained-will-the-tropics-eventually-become-uninhabitable-145174">Climate explained: will the tropics eventually become uninhabitable?</a>
</strong>
</em>
</p>
<hr>
<h2>What can be done to protect people?</h2>
<p>Current climate monitoring efforts have left millions of vulnerable people at risk of heat stress. This has direct <a href="https://journals.plos.org/climate/article?id=10.1371/journal.pclm.0000339">impacts on individual health and wellbeing</a>, with <a href="https://doi.org/10.1016/S0140-6736(23)01859-7">broader knock-on effects</a> for societies and national economies. </p>
<p>Meteorological institutes in developing countries need urgent support to strengthen climate monitoring and improve early-warning systems. The new head of the World Meteorological Organisation has <a href="https://wmo.int/news/media-centre/celeste-saulo-of-argentina-takes-office-secretary-general-of-wmo">promised to do just that</a>. We need to ensure governments and agencies, such as development banks and NGOs, capitalise on this opportunity and include informal settlements in new monitoring networks.</p>
<p>Inequalities in resources and adaptive capacities must also be overcome. Community-based initiatives such as urban greening and improved housing <a href="https://doi.org/10.1016/S0140-6736(21)01209-5">show promise to reduce urban heat</a>. Investing in these solutions must be a priority of adaptation efforts. </p>
<p>The alternative to adapting is to move. Climate-related migration is <a href="https://www.visionofhumanity.org/wp-content/uploads/2023/11/ETR-2023-web-261023.pdf">already happening</a> due to sea-level rise and heat, <a href="https://www.abc.net.au/news/2019-12-16/climate-migrants-moving-south-to-tasmania/11800152">including here in Australia</a>. </p>
<p>People don’t leave their homes and uproot their lives without good reason. Finding solutions that help them adapt to climate change should be the priority. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/climigration-when-communities-must-move-because-of-climate-change-122529">'Climigration': when communities must move because of climate change</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/221313/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Emma Ramsay received funding from the Australian Government Research Training Program and Monash University. This research was conducted as part of the Revitalising Informal Settlements and their Environments (RISE) program, funded by the Wellcome Trust, the New Zealand Ministry of Foreign Affairs and Trade, the Australian Department of Foreign Affairs and Trade, the Asian Development Bank, the Government of Fiji, the City of Makassar and Monash University, and involves partnerships and in-kind contributions from the Cooperative Research Centre for Water Sensitive Cities, Fiji National University, Hasanuddin University, Southeast Water, Melbourne Water, Live and Learn Environmental Education, UN-Habitat, UNU-IIGH, WaterAid International and Oxfam</span></em></p>Most of the 1 billion people in informal settlements are in the tropics where the threat of humid heat is rising. Poor weather station coverage that misses local hotspots puts them even more at risk.Emma Ramsay, Postdoctoral Research Fellow, Nanyang Technological University, and Research Affiliate, School of Biological Sciences, Monash UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2143432023-09-28T12:29:06Z2023-09-28T12:29:06ZTropical climates are the most biodiverse on Earth − but it’s not only because of how warm and wet they are<figure><img src="https://images.theconversation.com/files/550347/original/file-20230926-17-14uatg.jpg?ixlib=rb-1.1.0&rect=179%2C40%2C5115%2C3013&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Natural selection can get to work in isolated locations.</span> <span class="attribution"><a class="source" href="https://unsplash.com/photos/YLoZAyUKVv8">Birger Strahl/Unsplash</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>Life exists in every conceivable environment on Earth, from the peaks of towering mountains to the remote stretches of isolated islands, from sunlit surfaces to the darkest depths of the oceans. Yet, this intricate tapestry of existence isn’t spread uniformly.</p>
<p>For centuries, scientists have marveled at the extraordinary variety of species exhibited in tropical regions. The breathtaking biodiversity of the Amazon rainforest, the teeming life in Madagascar’s unique ecosystems, the species-rich cloud forests of Costa Rica – the tropics showcase nature’s opulence.</p>
<p>What makes the tropics so incredibly diverse?</p>
<p>Since the dawn of biodiversity studies, scientists have believed the predominant factor is <a href="https://www.britannica.com/science/climate-meteorology">climate</a> – the long-term patterns of temperature, precipitation and other atmospheric conditions. Thinkers like <a href="https://theconversation.com/the-most-influential-scientist-you-may-never-have-heard-of-35285">Alexander von Humboldt</a> set the stage in the early 19th century with their keen observations, highlighting how life-rich regions <a href="https://doi.org/10.1016/S0169-5347(01)02197-8">often shared certain climatic features</a>. Fast-forward to the present, and scientists <a href="https://doi.org/10.1111/ecog.05613">confidently correlate climate with biodiversity</a>. Simply put, hotter, wetter, resource-rich regions are veritable cradles of life.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/550930/original/file-20230928-29-ohb2bq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="hilly landscape descending toward blue inlet" src="https://images.theconversation.com/files/550930/original/file-20230928-29-ohb2bq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/550930/original/file-20230928-29-ohb2bq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/550930/original/file-20230928-29-ohb2bq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/550930/original/file-20230928-29-ohb2bq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/550930/original/file-20230928-29-ohb2bq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/550930/original/file-20230928-29-ohb2bq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/550930/original/file-20230928-29-ohb2bq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The Mediterranean climate is named after where it occurs in Southern Europe, but similar isolated conditions are scattered across the globe in parts of California, central Chile, the Western Cape of South Africa and southwestern Australia.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/oludeniz-royalty-free-image/1155048315">bodrumsurf/iStock via Getty Images Plus</a></span>
</figcaption>
</figure>
<p>Some climatic conditions spread across vast landscapes, while others appear fragmented, resembling isolated islands amid varying climates. This difference raises an intriguing question: Is an area’s biodiversity solely due to its climate? Or do the size and relative isolation of these climatic pockets influence the richness and abundance of species that thrive within them?</p>
<p><a href="https://scholar.google.com/citations?user=9zfvf9kAAAAJ&hl=en&oi=ao">We are part of</a> <a href="https://scholar.google.com/citations?user=WUFF6hMAAAAJ&hl=en&oi=ao">an international</a>, <a href="https://scholar.google.com/citations?user=BtH6Zm0AAAAJ&hl=en&oi=ao">interdisciplinary team</a> interested in the puzzle of how the geography of climate and the global patterns of species diversity fit together. Geography of climate is a bigger part of the biodiversity picture than previously assumed, according to our study findings <a href="https://doi.org/10.1038/s41586-023-06577-5">recently published in the journal Nature</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/550763/original/file-20230927-25-dnpvu6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="map of continents showing areas with more amphibian species marked red, mostly in the tropics" src="https://images.theconversation.com/files/550763/original/file-20230927-25-dnpvu6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/550763/original/file-20230927-25-dnpvu6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=302&fit=crop&dpr=1 600w, https://images.theconversation.com/files/550763/original/file-20230927-25-dnpvu6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=302&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/550763/original/file-20230927-25-dnpvu6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=302&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/550763/original/file-20230927-25-dnpvu6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=380&fit=crop&dpr=1 754w, https://images.theconversation.com/files/550763/original/file-20230927-25-dnpvu6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=380&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/550763/original/file-20230927-25-dnpvu6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=380&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Researchers commonly consider the geographical distribution of species, as displayed on this map highlighting the number of amphibian species across various regions of the world.</span>
<span class="attribution"><span class="source">Marco Túlio Pacheco Coelho</span></span>
</figcaption>
</figure>
<h2>Unraveling the geography of climate</h2>
<p>Historically, to study global biodiversity patterns, researchers divided the world into equal area grids and counted the species in each square.</p>
<p>Our study diverged from conventional methods. Instead of focusing solely on specific geographical locations, we centered our attention on the unique climate profiles of regions. Essentially, we weren’t just looking at plots on Earth but every place that shared a particular set of climatic conditions. We then classified these conditions globally and meticulously counted the species – birds, mammals, amphibians and reptiles – that live within the boundaries of each climate.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/550764/original/file-20230927-21-ad52h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="a heat map of amphibian richness along a horizontal axis from cold to warm and a vertical axis from wet to dry" src="https://images.theconversation.com/files/550764/original/file-20230927-21-ad52h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/550764/original/file-20230927-21-ad52h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=447&fit=crop&dpr=1 600w, https://images.theconversation.com/files/550764/original/file-20230927-21-ad52h.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=447&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/550764/original/file-20230927-21-ad52h.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=447&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/550764/original/file-20230927-21-ad52h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=562&fit=crop&dpr=1 754w, https://images.theconversation.com/files/550764/original/file-20230927-21-ad52h.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=562&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/550764/original/file-20230927-21-ad52h.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=562&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Mapping species in this climate space, rather than traditional geographical analyses of species diversity, revealed deeper insights into the relationships between biodiversity and climate.</span>
<span class="attribution"><span class="source">Marco Túlio Pacheco Coelho</span></span>
</figcaption>
</figure>
<p>Central to our investigation was an exploration of the geography of these climates, examining both their size and isolation. Some climates are widespread and common, sprawling over vast areas. Others are more fragmented, emerging as isolated pockets amid different climatic zones, reminiscent of islands in a vast ocean of other diverse climates. Consider tropical climates: They cover vast expanses cumulatively, despite being broken up into smaller, unconnected bits, even on different continents.</p>
<p><a href="https://doi.org/10.1038/s41586-023-06577-5">Our findings were illuminating</a>. Climate, of course, was an important factor in how many species flourished in a location. But we were intrigued to find that about a third of the variation we found in species diversity across the globe can be attributed solely to the size and degree of isolation of all the instances of a particular climate. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/550772/original/file-20230927-27-d71col.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="lush green forest scene" src="https://images.theconversation.com/files/550772/original/file-20230927-27-d71col.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/550772/original/file-20230927-27-d71col.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/550772/original/file-20230927-27-d71col.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/550772/original/file-20230927-27-d71col.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/550772/original/file-20230927-27-d71col.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/550772/original/file-20230927-27-d71col.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/550772/original/file-20230927-27-d71col.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The warm, resource-rich Costa Rican tropical forest bursts with biodiversity − partly because it’s a unique climate island amid a vast ocean of varying conditions.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/cloud-forest-from-costa-rica-royalty-free-image/532812903">bogdanhoria/iStock via Getty Images Plus</a></span>
</figcaption>
</figure>
<p>Biodiversity responds not just to the type of climate but its <a href="https://www.nature.com/articles/d41586-023-02937-3">spatial distribution</a>. Beyond the known effects of warmth and moisture, we found that larger and more isolated climates foster greater species diversity. Moreover, these expansive, broken-up climates not only housed a greater number of species but also nurtured a more unique combination of species.</p>
<p>By leveraging but transcending traditional methodologies, our approach unearthed novel insights about the geographical characteristics of climates. We discovered that the larger a climatic zone is, the more fragmented and scattered it tends to be across the landscape.</p>
<h2>Isolation spurs diversity</h2>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/550245/original/file-20230926-29-50omss.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="sea of snowy pine trees on mountainous terrain" src="https://images.theconversation.com/files/550245/original/file-20230926-29-50omss.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/550245/original/file-20230926-29-50omss.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=900&fit=crop&dpr=1 600w, https://images.theconversation.com/files/550245/original/file-20230926-29-50omss.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=900&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/550245/original/file-20230926-29-50omss.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=900&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/550245/original/file-20230926-29-50omss.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1131&fit=crop&dpr=1 754w, https://images.theconversation.com/files/550245/original/file-20230926-29-50omss.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1131&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/550245/original/file-20230926-29-50omss.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1131&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Cooler extra-tropical climates connect more cohesively around the globe.</span>
<span class="attribution"><a class="source" href="https://unsplash.com/photos/kKadFByUqEo">Ciprian Boiciuc/Unsplash</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Traditionally, scientists have thought of tropical climates as cohesive expanses, standing as <a href="https://doi.org/10.1146/annurev.ecolsys.34.012103.144032">barriers between the distinct extra-tropical climates</a> of our planet’s poles. Our analysis confirmed that cooler extra-tropical climates are relatively well connected across much of the planet.</p>
<p>Yet, our findings reveal a different narrative for the tropics: Tropical climates appear more as fragmented islands amid a sea of diverse climates, rather than expansive, interconnected realms. Our revelation underscores that tropical climates, while abundant, are dispersed and disjointed across the Earth’s surface.</p>
<p>Drawing a parallel, consider how mountainous regions harbor <a href="https://theconversation.com/why-are-so-many-languages-spoken-in-some-places-and-so-few-in-others-116573">isolated valleys where people speak distinct dialects</a> shaped by their seclusion. Nature mirrors this: Species in isolated climatic niches evolve distinctly, creating a diverse and unique tableau of life.</p>
<p>The <a href="https://theconversation.com/climate-change-could-cause-abrupt-biodiversity-losses-this-century-135968">specter of climate change</a>, however, casts a long shadow over these insights. A world undergoing rapid warming might witness once vast climates fragmenting further. Such shifts could challenge species, compelling them to traverse daunting landscapes to find suitable habitats. If these once expansive climates recede, it could disrupt the entire balance of species interactions.</p>
<p>Understanding the interplay between biodiversity and climate is not merely an intellectual pursuit. It provides direction in helping people protect and appreciate the diverse symphony of life in our evolving world.</p><img src="https://counter.theconversation.com/content/214343/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Catherine Graham receives funding from Swiss National Fund, European Research Council. </span></em></p><p class="fine-print"><em><span>Dave Roberts received a stipend from WSL when he was a Fellow there during his stay in Switzerland when this work was initiated.</span></em></p><p class="fine-print"><em><span>Marco Túlio Pacheco Coelho does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>A new study reveals how the geography of global climates influences the rich patterns of species diversity in an ever-changing world.Marco Túlio Pacheco Coelho, Postdoctoral research associate, Swiss Federal Institute for Forest, Snow and Landscape Research (WSL)Catherine Graham, Senior Researcher at Swiss Federal Institute for Forest, Snow and Landscape Research and Adjunct Associate Professor of Ecology and Evolution, Stony Brook University (The State University of New York)Dave Roberts, Professor Emeritus of Ecology, Montana State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2082692023-07-11T12:29:02Z2023-07-11T12:29:02ZSawfish, guitarfish and more: Meet the rhino rays, some of the world’s most oddly shaped and highly endangered fishes<figure><img src="https://images.theconversation.com/files/536338/original/file-20230707-2339-cd9dxd.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C2891%2C1937&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">An Atlantic guitarfish swimming in the Gulf of Mexico.
</span> <span class="attribution"><a class="source" href="https://flic.kr/p/8UpjyX">NOAA SEFSC Pascagoula Laboratory/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>“Shark!” When you hear this word, especially at the beach, it can conjure up images of bloodthirsty monsters. This summer, my colleagues and I are eager to help the public learn more about these misunderstood, ecologically important and highly threatened animals and <a href="https://www.britannica.com/animal/chondrichthian">their close relatives – rays and chimaeras</a>. </p>
<p>As a <a href="https://scholar.google.com/citations?user=xb7noGAAAAAJ&hl=en">marine biologist focused on conserving sharks</a>, I want people to know that an estimated one-third of them are <a href="https://doi.org/10.1016/j.cub.2021.08.062">at risk of extinction</a>. Second, there’s an amazing variety of species in an astounding variety of shapes sizes and colors, and many of them get very little attention. </p>
<p>Here is an introduction to a group of fishes that are at <a href="https://www.iucnssg.org/press/a-special-group-of-rays-are-now-worlds-most-threatened-marine-fish">extremely high risk of extinction</a>, and also delightfully weird: the rhino rays, named for their <a href="https://researchers.cdu.edu.au/en/publications/most-rhino-rays-sawfishes-wedgefishes-giant-guitarfishes-guitarfi">elongated noses</a>. </p>
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<figcaption><span class="caption">Scientists tag endangered sawfish off Florida’s west coast to identify and protect their habitats and educate the public about them.</span></figcaption>
</figure>
<h2>Motley shapes</h2>
<p>Rhino rays are sharklike rays from five families: sawfish, wedgefish, giant guitarfish, guitarfish and banjo rays. The <a href="https://www.floridamuseum.ufl.edu/discover-fish/teaching-resources/sawfish-classroom-activities/what-is-a-sawfish/">sawfish</a> has a chainsaw-like extension in front of its mouth that it uses to stun and shred its prey. <a href="https://www.inaturalist.org/taxa/114627-Trygonorrhina-fasciata">Banjo rays</a> and <a href="https://www.fisheries.noaa.gov/species/common-guitarfish">guitarfishes</a> have body shapes that resemble those respective musical instruments. <a href="https://citessharks.org/wedgefishes">Wedgefishes</a> are, well, wedge-shaped, like doorstops with fins and tails. </p>
<p>These fishes are found in tropical and warm temperate waters all over the world, but many species have extremely restricted ranges. For example, the <a href="https://shark-references.com/species/view/Rhynchorhina-mauritaniensis">false shark ray</a> (<em>Rhynchorhina mauritaniensis</em>) is known to inhabit only one bay, on the coastline of Mauritania. </p>
<p>Rhino rays range in size, from 2 to 3 feet long (less than 1 meter) at one extreme to the largest species, the <a href="https://www.fisheries.noaa.gov/species/green-sawfish">green sawfish</a> (<em>Pristis zijsron</em>), which can grow to 23 feet (7 meters). They all are carnivores and eat all kinds of things, but mainly small crustaceans and fish, as well as worms that live in sand or mud. All rhino rays give birth to live young, just as mammals do. </p>
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<figcaption><span class="caption">Scientists capture footage of a sawfish giving birth in the wild.</span></figcaption>
</figure>
<h2>Conservation strategies</h2>
<p>Sometimes rhino rays’ unusual features cause them problems. For example, fishing boats often haul in <a href="https://www.fisheries.noaa.gov/species/smalltooth-sawfish">smalltooth sawfish</a> (<em>Pristis pectinata</em>) as bycatch, or accidental catch, because their saws become tangled in fishing gear. Currently, shrimp trawl nets pose a serious threat to this species.</p>
<p>The smalltooth sawfish was the first marine fish species <a href="https://ecos.fws.gov/ecp/species/3253">listed under the U.S. Endangered Species Act</a>, in 2003. Once found from North Carolina to Texas, it now is restricted to small parts of south Florida, a range reduction of more than 95%. In some parts of the world, populations are starting to recover, but local extinction of sawfish from countries where they were once so common that they’re featured on currency has earned them the nickname “<a href="https://doi.org/10.1002/aqc.2525">Ghosts of the Coast</a>.” </p>
<p>Another rhino ray, the <a href="https://www.aquariumofpacific.org/onlinelearningcenter/species/bowmouth_guitarfish">bowmouth guitarfish</a> (<em>Rhina ancylostomus</em>), can grow up to 10 feet (3 meters) and has thornlike ridges covering its head and back. A recent study reported that these thorns are <a href="https://doi.org/10.1111/csp2.12896">actively traded online</a> among buyers who believe the thorns contain magical properties and use them to make protective amulets. While <a href="https://www.science.org/content/article/most-high-seas-shark-species-now-threatened-extinction">overfishing for fins and meat</a> is the most serious threat to sharks and rays overall, it also is important to consider these kinds of niche threats to some species.</p>
<p><div data-react-class="InstagramEmbed" data-react-props="{"url":"https://www.instagram.com/p/CHtTyrqlQw7/?utm_source=ig_web_copy_link\u0026igshid=MzRlODBiNWFlZA==","accessToken":"127105130696839|b4b75090c9688d81dfd245afe6052f20"}"></div></p>
<p>Fortunately, there are <a href="https://doi.org/10.1111/acv.12265">conservation solutions</a> that can be used to protect these animals and their important habitats. To reduce bycatch, some solutions require changing fishing gear. </p>
<p>“For gill nets, simple measures like lifting the net off the seafloor so sawfish have space to swim under them without getting tangled can help,” <a href="https://scholar.google.com.au/citations?user=bu2A-2kAAAAJ&hl=en">Charles Darwin University biologist Peter Kyne</a> told me in an interview. Using lights to illuminate nets has drastically reduced bycatch in some places. Kyne and his colleagues are testing <a href="https://doi.org/10.3354/esr01146">devices that generate electric fields underwater</a> to make sawfish swim away from nets so they don’t get entangled. </p>
<p>When bycatch can’t be averted, another strategy is training fishers to safely handle and release nontargeted species so that the fishes survive the encounter. Release-based conservation initiatives are an opportunity for scientists to <a href="https://doi.org/10.1111/acv.12651">collaborate with fishing communities</a> and the public. </p>
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<figcaption><span class="caption">Researchers interview people in fishing communities in Goa, India, to understand the behavior of critically endangered guitarfishes and wedgefishes.</span></figcaption>
</figure>
<p>“For sawfishes, we started conservation work when species had already disappeared from across their historical range. We now have an opportunity to save the remaining species of rhino rays before it’s too late,” Rima Jabado, chair of the Shark Specialist Group for the International Union for the Conservation of Nature’s <a href="https://www.iucn.org/our-union/commissions/species-survival-commission">Species Survival Commission</a>, told me in an interview. “We know that fishing is the primary threat, and we have solutions to minimize bycatch.” </p>
<p>To learn more about rhino rays, follow #RhinoRay on Twitter and Instagram for posts from scientists, conservation experts, government agencies, zoos and aquariums all over the world. You can find the IUCN Species Survival Commission Shark Specialist Group on Twitter, Facebook and LinkedIn for weekly updates about the conservation status of these amazing and threatened animals. </p>
<p><em>Rima Jabado, chair of the IUCN Species Survival Commission Shark Specialist Group (SSG), contributed to this article.</em></p><img src="https://counter.theconversation.com/content/208269/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>David Shiffman currently serves as the communications officer for the IUCN Species Survival Commission Shark Specialist Group</span></em></p>Rhino rays, which are close relative of sharks, are some of the most fascinating – and most threatened – fishes that you’ve never heard of.David Shiffman, Faculty Research Associate in Marine Biology, Arizona State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1885042022-11-03T12:00:39Z2022-11-03T12:00:39ZOlive ridley sea turtles are constantly on the move, so protective zones should follow them<figure><img src="https://images.theconversation.com/files/492819/original/file-20221101-25187-w4klf3.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C7090%2C4732&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">An olive ridley swims Into the wild blue yonder.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/a-olive-ridleys-turtle-swimming-below-the-surface-royalty-free-image/524867607">Gerard Soury/The Image Bank via Getty Images</a></span></figcaption></figure><p>Many of the ocean’s most charismatic animals spend their lives swimming, flying or gliding thousands of miles, from the coasts to the high seas. Arctic terns, humpback whales and sea turtles are examples. Scientists have spent many years documenting and studying these magnificent journeys. </p>
<p>Chronicling where these species go is just the beginning. The next steps are understanding when and how far each animal travels and what triggers it to roam. </p>
<p>We are a <a href="https://scholar.google.com/citations?user=BQNRM-8AAAAJ&hl=en">marine biologist</a> and an <a href="https://scholar.google.com/citations?user=4vqRTOAAAAAJ&hl=en">evolutionary ecologist</a> and have worked together to study the nesting and migration habits of <a href="https://ecos.fws.gov/ecp/species/1513#v">endangered olive ridley sea turtles</a> (<em>Lepidochelys</em> <em>olivacea</em>). This information is vital for managing the turtles’ recovery – but our research shows that two identical-looking olive ridleys may follow very different paths. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/492817/original/file-20221101-23-ma4us.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="World map with tropical oceans highlighted" src="https://images.theconversation.com/files/492817/original/file-20221101-23-ma4us.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/492817/original/file-20221101-23-ma4us.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=304&fit=crop&dpr=1 600w, https://images.theconversation.com/files/492817/original/file-20221101-23-ma4us.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=304&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/492817/original/file-20221101-23-ma4us.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=304&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/492817/original/file-20221101-23-ma4us.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=382&fit=crop&dpr=1 754w, https://images.theconversation.com/files/492817/original/file-20221101-23-ma4us.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=382&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/492817/original/file-20221101-23-ma4us.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=382&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Approximate range of olive ridley sea turtles.</span>
<span class="attribution"><a class="source" href="https://www.fisheries.noaa.gov/species/olive-ridley-turtle">NOAA</a></span>
</figcaption>
</figure>
<h2>Protecting animals that move</h2>
<p>Mapping the spatial distribution and movement patterns of marine animals that are endangered or threatened is essential for defining <a href="https://www.fisheries.noaa.gov/national/endangered-species-conservation/critical-habitat">critical habitat</a> – areas that these species need in order to recover, such as key breeding or feeding grounds.</p>
<p>Once scientists identify critical habitats, governments can integrate them into <a href="https://marineprotectedareas.noaa.gov/aboutmpas/">marine protected areas</a>. These typically are defined zones with fixed borders. They benefit marine animals that stay in one place, like sea anemones; have small ranges; and require specific habitats, such as coral reefs or seagrass beds. </p>
<p>But highly migratory marine animals have large ranges and can travel many miles per day. They may prefer a certain location one year and a different one the next year. And their movements are driven by shifting ocean circulation patterns. Marine protected areas <a href="https://theconversation.com/to-conserve-ocean-life-marine-reserves-need-to-protect-species-that-move-around-89907">are not effective</a> for protecting highly mobile species – and olive ridley sea turtles are incredibly mobile. </p>
<h2>Ocean nomads</h2>
<p>Olive ridleys are among the smallest of the world’s sea turtles and are found in the tropical Atlantic, Pacific and Indian oceans. They are best known for their signature <a href="https://www.fisheries.noaa.gov/species/olive-ridley-turtle">synchronized mass nestings on beaches</a> in early summer, which are called arribadas – Spanish for “arrival.”</p>
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<figcaption><span class="caption">Thousands of female olive ridley sea turtles nest in an arribada in Costa Rica.</span></figcaption>
</figure>
<p>Fishing in the eastern Pacific Ocean decimated nesting colonies of olive ridleys before commercial exploitation ended in the 1980s. The species has begun to recover but remains <a href="https://www.iucnredlist.org/species/11534/3292503">listed as vulnerable</a> by the <a href="https://www.iucn.org/">International Union for the Conservation of Nature</a>. The U.S. <a href="https://ecos.fws.gov/ecp/species/1513">classifies olive ridleys as threatened</a>, except for a group that nests on Mexico’s Pacific coast that is classified as endangered. <a href="https://www.fisheries.noaa.gov/species/olive-ridley-turtle#">Threats</a> include fishing, hunting of eggs and turtles on nesting beaches, coastal development, boat collisions and water pollution.</p>
<p>One of us, Pamela Plotkin, began studying olive ridleys in 1990, when satellite telemetry first emerged as a viable tool for following them at sea. Initially, Plotkin expected to document groups of turtles migrating from their mass nesting beach in Costa Rica to an undiscovered feeding ground in the eastern Pacific Ocean, far from land. </p>
<p>Adult female sea turtles typically have a predetermined endpoint where they go to feed after they finish nesting on beaches. It was easy to imagine throngs of turtles migrating in “turtle schools” between the beach and their feeding ground. </p>
<p>Plotkin envisioned creating a simple conservation plan to protect the migratory corridor linking these two critical habitats. But she <a href="https://doi.org/10.1007/BF00349287">found nothing of the sort</a>.</p>
<p>Instead, she learned, <a href="http://dx.doi.org/10.3354/esr00314">olive ridleys’ journey has no endpoint</a>. They swim hundreds to thousands of miles from their nesting beach, moving continuously among multiple areas, following unpredictable and widely dispersed pathways that vary year to year. </p>
<p>Clearly, there was a need to better define critical habitat for this highly mobile turtle in a huge expanse of ocean. </p>
<h2>Searching for the sweet spot</h2>
<p>In 2015, with the addition of doctoral student <a href="https://www.seaturtlebiologist.com/">Christine Figgener</a>, our research group picked up where prior studies had left off. Part of Figgener’s dissertation research focused on characterizing critical habitat for olive ridleys in the eastern Pacific Ocean and understanding their habitat preference based on <a href="https://doi.org/10.3389/fevo.2022.933424">changing environmental variables</a>. They included sea surface temperature and concentrations of chlorophyll-a, which is found in marine algae, an essential food source for the diverse plankton that <a href="https://doi.org/10.3389/fmars.2017.00348">olive ridleys eat</a>.</p>
<p>Figgener captured olive ridleys from multiple beaches in Costa Rica, including turtles that nested alone rather than in large groups. She glued satellite trackers to 23 turtles’ shells and followed them from their nesting beaches. We also acquired satellite data on conditions including sea surface temperature, chlorophyll-a concentrations and how deeply sunlight penetrated into the upper ocean in areas where the turtles traveled. </p>
<p>By combining old and new data, with a total of 43 different migration tracks and 1,553 in-water turtle locations, we identified high-use areas for olive ridleys between Mexico and Peru and developed a habitat preference model to understand what attracts turtles to specific areas. </p>
<h2>Predictably unpredictable</h2>
<p>The female olive ridleys that we tracked swam long distances north, west and south from Costa Rica. Their routes did not overlap, and their movements did not reveal any well-defined migratory corridor of the kind that many species follow. </p>
<p>We mapped the areas where these nomads clustered, and found that their high-use areas spanned the exclusive economic zones – areas extending up to 200 miles offshore – of six countries: <a href="https://doi.org/10.3389/fevo.2022.933424">Mexico, Guatemala, El Salvador, Nicaragua, Costa Rica and Panama</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/492818/original/file-20221101-26-j9prao.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Map showing olive ridley distribution in the eastern Pacific" src="https://images.theconversation.com/files/492818/original/file-20221101-26-j9prao.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/492818/original/file-20221101-26-j9prao.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=804&fit=crop&dpr=1 600w, https://images.theconversation.com/files/492818/original/file-20221101-26-j9prao.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=804&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/492818/original/file-20221101-26-j9prao.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=804&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/492818/original/file-20221101-26-j9prao.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1011&fit=crop&dpr=1 754w, https://images.theconversation.com/files/492818/original/file-20221101-26-j9prao.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1011&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/492818/original/file-20221101-26-j9prao.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1011&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">These images show olive ridley high-use areas in the eastern Pacific. Black dots are satellite tracker locations. Important areas are yellow (figure A), critical areas are red (figures A and B), and exclusive economic zones are marked by yellow lines (figure B).</span>
<span class="attribution"><a class="source" href="https://www.frontiersin.org/files/Articles/933424/fevo-10-933424-HTML-r1/image_m/fevo-10-933424-g002.jpg">Figgener et al., 2022.</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>When we compared high-use areas for mass nesting turtles with those of solitary nesting turtles, we saw striking differences. Mass-nesting turtles clustered into one large, connected area that was smaller and closer to the coastline. Solitary nesting turtles’ high-use areas were disconnected, widely dispersed and farther from the coast. </p>
<p>Our model indicated that the turtles preferred habitat where the water was warmer than about 77 degrees Fahrenheit (25 degrees Celsius) and deeper than 13,000 feet (4,000 meters), and where phytoplankton were abundant. </p>
<h2>A conservation challenge</h2>
<p>Current conservation strategies for sea turtles typically emphasize <a href="https://doi.org/10.1371/journal.pbio.0060171">protecting static migratory corridors</a>. But this approach won’t benefit nomadic olive ridleys. Instead, these turtles’ wide-ranging migrations and shifting use of space require a <a href="https://doi.org/10.1093/biosci/biv018">dynamic ocean management</a> strategy. This approach uses real-time data to track target animals where they are and creates movable protected zones in a changing environment. </p>
<p>Dynamic management has been used successfully in developed countries to reduce threats to <a href="https://doi.org/10.1016/j.marpol.2015.03.014">whales, fish and sea turtles</a> from capture in fisheries and vessel strikes. It integrates many kinds of data, including satellite tracking, voluntary catch reports from fishermen and modeling of target species’ habitat preferences. Information is quickly shared via mobile apps so that, for example, ship captains are alerted to reduce vessel speed when whales are likely to be nearby. </p>
<p>Expanding this approach to developing countries poses a challenge, but is <a href="https://doi.org/10.1017/S0030605312000105">within reach</a>. A dynamic management system for olive ridleys would need to predict where the turtles are likely to be present in a perpetually changing environment, and address threats in these critical spaces. It also would require nations to work together to regulate fisheries that capture and threaten turtles in their territorial waters. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1515403902434562048"}"></div></p>
<p>Another important angle of our research is the contrast we found between habitat use by mass-nesting turtles and solitary-nesting turtles. It supports previous studies that found <a href="https://press.jhu.edu/books/title/9346/biology-and-conservation-ridley-sea-turtles">two distinct groups of turtles within the same population</a>. </p>
<p>Conservation efforts on nesting beaches have focused mainly on protecting a small number of beaches in Mexico and Costa Rica that olive ridleys use for mass nestings. But hundreds of solitary nesting beaches extending from Mexico to Ecuador are largely unprotected. These turtles <a href="https://www.iucnredlist.org/species/11534/3292503">have declined significantly in number in recent years</a>. We contend that conserving olive ridleys will require action both on land and at sea.</p><img src="https://counter.theconversation.com/content/188504/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Pamela T. Plotkin received funding from the National Science Foundation for a portion of the research described in this article. Doctoral student Christine Figgener received funding from multiple sources to support some of the research described in this article including the Lerner-Gray-Fund for Marine Research, Texas Sea Grant, and the George H. W. Bush Presidential Library Foundation </span></em></p><p class="fine-print"><em><span>Joseph Bernardo does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Standard marine protected areas with fixed boundaries can’t effectively shelter these ocean nomads.Pamela T. Plotkin, Associate Research Professor and Director, Texas Sea Grant, Texas A&M UniversityJoseph Bernardo, Research Associate Professor of Biology, Texas A&M UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1877412022-09-20T20:14:01Z2022-09-20T20:14:01ZClimate change is making rain difficult to predict – we trained an AI to help tropical countries adapt<figure><img src="https://images.theconversation.com/files/484600/original/file-20220914-11-jn6m9j.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C5892%2C3925&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/moment-where-cumulonimbus-storm-cloud-gathered-1291824019">Muhammad Qadri Anwar/Shutterstock</a></span></figcaption></figure><p>While rivers and reservoirs run <a href="https://theconversation.com/rivers-worldwide-are-running-dry-heres-why-and-what-we-can-do-about-it-189270">dangerously low</a> in Europe, there is catastrophic flooding in <a href="https://theconversation.com/a-climate-scientist-on-the-planets-simultaneous-disasters-from-pakistans-horror-floods-to-europes-record-drought-189626">Pakistan</a> and <a href="https://theconversation.com/americas-summer-of-floods-what-cities-can-learn-from-todays-climate-crises-to-prepare-for-tomorrows-189293">the US</a>. Whether it’s a drought or a deluge, being able to accurately forecast rain is important to protect lives and manage water safely.</p>
<p>That has become more difficult in recent decades. Climate change and deforestation have <a href="https://theconversation.com/human-disruption-to-earths-freshwater-cycle-has-exceeded-the-safe-limit-our-research-shows-182562">warped Earth’s freshwater cycle</a>, shifting rainfall patterns towards extreme events like severe droughts and downpours. Catastrophic floods have been on the rise globally <a href="https://public.wmo.int/en/media/press-release/weather-related-disasters-increase-over-past-50-years-causing-more-damage-fewer">in the last 50 years</a> and incidences of flash flooding, when torrential rain falls in a very short period, have increased, particularly in tropical countries where <a href="https://www.youtube.com/watch?v=Z6EjpKN9ai0">high temperatures</a> have made <a href="https://www.nssl.noaa.gov/education/svrwx101/thunderstorms/">thunderstorms</a> more common.</p>
<p>Developed countries like the UK have invested in satellites and radars for more accurate weather forecasting. These high-tech systems are particularly effective in temperate climates where rainfall typically occurs over <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2008RS003984">several kilometres</a> and moves in wide bands known as weather fronts. Measurements of rainfall over distances of 5 km or greater, which satellites and radars are capable of, are often sufficient for forecasting rain at this scale. </p>
<p>In tropical countries, where climate change is expected to have a far <a href="https://www.concern.net/news/countries-most-affected-by-climate-change">greater impact</a>, systems that can forecast rain at distances of less than a kilometre are needed. This is because of something called <a href="https://www.internetgeography.net/topics/what-is-convectional-rainfall/">convectional rainfall</a>, which is common in the tropics. </p>
<p>Convectional rainfall occurs when heated air rises upwards along with water vapour, which condenses to form clouds at a high altitude. These clouds are not carried away by the wind, and so rain falls in the same place it originated. </p>
<p>Systems capable of forecasting convectional rainfall would help authorities give advance warning, preventing deaths and flood damage. They could also help people manage this rainwater to benefit farms, with efficient drainage and irrigation measures.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/RkgThul2El8?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<p>Most tropical countries fall within <a href="https://worldpopulationreview.com/country-rankings/low-income-countries">low or middle income</a> bands. Forecasting rain over distances smaller than a kilometre is expensive – weather satellites are often not feasible. Dense vegetation and hilly terrain, also common in tropical regions, can profoundly shape local weather by causing <a href="https://www.internetgeography.net/topics/what-is-convectional-rainfall/">humid air to rise and condense</a>, making conventional weather forecasting even trickier.</p>
<p>To solve these problems, we set out to develop a cheap way of providing street-by-street forecasting.</p>
<h2>AI-based tropical rainfall forecasting</h2>
<p>Rainfall is the result of complex interactions between different components of the atmosphere such as temperature, humidity, pressure and wind speed which can be easily measured by sensors. We investigated whether artificial intelligence could use this information to compile a rainfall forecast in northern Malaysia. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/484633/original/file-20220914-9486-tykdiw.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A 3D illustration of a landscape with weather sensors linked in a network." src="https://images.theconversation.com/files/484633/original/file-20220914-9486-tykdiw.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/484633/original/file-20220914-9486-tykdiw.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=423&fit=crop&dpr=1 600w, https://images.theconversation.com/files/484633/original/file-20220914-9486-tykdiw.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=423&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/484633/original/file-20220914-9486-tykdiw.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=423&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/484633/original/file-20220914-9486-tykdiw.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=532&fit=crop&dpr=1 754w, https://images.theconversation.com/files/484633/original/file-20220914-9486-tykdiw.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=532&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/484633/original/file-20220914-9486-tykdiw.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=532&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Multiple sensors link up to form a network that can predict rainfall over a large area.</span>
<span class="attribution"><span class="source">Ogochukwu Ejike</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>The forecasting system we developed is essentially an intelligent computer programme that can predict whether it will rain, how intense that rain will be and how long it will last at any location with greater than 90% accuracy at least 96 hours in advance. </p>
<p>We tested its forecasting accuracy against past weather conditions which preceded rain falling. If this algorithm included data from sensors measuring the depth and flow rate of rivers, it could predict whether rain might cause flooding, and if so, when and for how long.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/485631/original/file-20220920-23-i7u8tz.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two line plots depicting forecasted rainfall intensity and duration and the actual values." src="https://images.theconversation.com/files/485631/original/file-20220920-23-i7u8tz.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/485631/original/file-20220920-23-i7u8tz.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=447&fit=crop&dpr=1 600w, https://images.theconversation.com/files/485631/original/file-20220920-23-i7u8tz.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=447&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/485631/original/file-20220920-23-i7u8tz.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=447&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/485631/original/file-20220920-23-i7u8tz.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=562&fit=crop&dpr=1 754w, https://images.theconversation.com/files/485631/original/file-20220920-23-i7u8tz.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=562&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/485631/original/file-20220920-23-i7u8tz.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=562&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">How the forecast compared with actual rainfall.</span>
<span class="attribution"><span class="source">Ogochukwu Ejike</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>The devices used to measure weather conditions can be connected to the internet to form a network that offers regional forecasting. Adding more devices to the network will improve the accuracy of the forecast, which is updated hourly.</p>
<p>Working with University of Malaysia Perlis, we have already created an online network of <a href="https://unisense.ceastech.com/?m=1.578842,105.766056,6">existing weather sensors</a> that collects data for our algorithm to use. Most of these weather stations are separated by tens of kilometres – too far apart to provide detailed rain forecasting in most areas. </p>
<p>But, as more sensors are added, the forecasting system will hopefully one day ensure that vulnerable communities can better prepare for extreme weather events, and build resilience to the rapidly changing climate.</p>
<hr>
<figure class="align-right ">
<img alt="Imagine weekly climate newsletter" src="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
</figcaption>
</figure>
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<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>High humidity, terrain and wind make rain forecasting particularly tricky in the tropics.Ogochukwu Ejike, PhD Candidate, Computing and Informatics, University of the West of ScotlandDavid Ndzi, Head of Computing, University of the West of ScotlandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1908312022-09-19T20:15:27Z2022-09-19T20:15:27ZEarth harbours 20,000,000,000,000,000 ants – and they weigh more than wild birds and mammals combined<figure><img src="https://images.theconversation.com/files/485266/original/file-20220919-20-399kqy.jpg?ixlib=rb-1.1.0&rect=0%2C302%2C5607%2C2606&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock </span></span></figcaption></figure><p>Have you ever wondered exactly how many ants live on Earth? Possibly not, but it’s certainly a question we’ve asked ourselves. </p>
<p>Our <a href="https://www.pnas.org/cgi/doi/10.1073/pnas.2201550119">research</a> published today provides an approximate answer. We conservatively estimate our planet harbours about 20 quadrillion ants. That’s 20 thousand million millions, or in numerical form, 20,000,000,000,000,000 (20 with 15 zeroes).</p>
<p>We further estimate the world’s ants collectively constitute about 12 million tonnes of dry carbon. This exceeds the mass of all the world’s wild birds and wild mammals combined. It’s also equal to about one-fifth of the total weight of humans. </p>
<p>Eminent biologist Edward O. Wilson once said insects and other invertebrates are “the little things that run the world” – and he was right. Ants, in particular, are a crucial <a href="https://harvardforest.fas.harvard.edu/ants/ecological-importance">part</a> of nature. Among other roles, ants aerate the soil, disperse seeds, break down organic material, create habitat for other animals and form an important part of the food chain. </p>
<p>Estimating ant numbers and mass provides an important baseline from which to monitor ant populations amid worrying environmental changes.</p>
<figure class="align-center ">
<img alt="two ants carry a seed" src="https://images.theconversation.com/files/485169/original/file-20220918-29066-y4whhk.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/485169/original/file-20220918-29066-y4whhk.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/485169/original/file-20220918-29066-y4whhk.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/485169/original/file-20220918-29066-y4whhk.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/485169/original/file-20220918-29066-y4whhk.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/485169/original/file-20220918-29066-y4whhk.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/485169/original/file-20220918-29066-y4whhk.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Many ant species are important seed dispersers. Here, two worker Meranoplus ants carry a seed back to their nest.</span>
<span class="attribution"><span class="source">Francois Brassard</span></span>
</figcaption>
</figure>
<h2>Counting the world’s ants</h2>
<p>There are more than 15,700 named species and subspecies of ants, and many others not yet named by science. Ants’ high degree of social organisation has enabled them to colonise nearly all ecosystems and regions around the globe.</p>
<p>The astounding ubiquity of ants has prompted many naturalists to <a href="https://www.bbc.com/news/magazine-29281253">contemplate</a> their exact number on Earth. But these were basically educated guesses. Systematic, evidence-based estimates have been lacking.</p>
<p>Our research involved an analysis of 489 studies of ant populations conducted by fellow ant scientists from around the world. This included non-English literature, in languages such as Spanish, French, German, Russian, Mandarin and Portuguese. </p>
<p>The research spanned all continents and major habitats including forests, deserts, grasslands and cities. They used standardised methods for collecting and counting ants such as pitfall traps and leaf litter samples. As you can imagine, this is often tedious work.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/in-defence-of-ants-186220">In defence of ants</a>
</strong>
</em>
</p>
<hr>
<figure class="align-center ">
<img alt="hand squeezes bottle of green liquid into hole in ground" src="https://images.theconversation.com/files/485168/original/file-20220918-47262-2jp0ey.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/485168/original/file-20220918-47262-2jp0ey.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/485168/original/file-20220918-47262-2jp0ey.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/485168/original/file-20220918-47262-2jp0ey.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/485168/original/file-20220918-47262-2jp0ey.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/485168/original/file-20220918-47262-2jp0ey.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/485168/original/file-20220918-47262-2jp0ey.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A researcher installs a pitfall trap, a standard method for collecting ants that crawl across the ground surface.</span>
<span class="attribution"><span class="source">Francois Brassard</span></span>
</figcaption>
</figure>
<p>From all this, we estimate there are approximately 20 quadrillion ants on Earth. This figure, though conservative, is between two and 20 times higher than previous estimates. </p>
<p>Th previous figures employed a “top-down” approach by assuming ants comprise about 1% of the world’s estimated insect population. In contrast, our “bottom-up” estimate is more reliable because it uses data on ants observed directly in the field and makes fewer assumptions.</p>
<p>Our next step was to work out how much all these ants weigh. The mass of organisms is <a href="https://www.pnas.org/doi/abs/10.1073/pnas.1711842115">typically measured</a> in terms of their carbon makeup. We estimated that 20 quadrillion average-sized ants corresponds to a dry weight or “biomass” of approximately 12 million tonnes of carbon. </p>
<p>This is more than the combined biomass of wild birds and mammals – and about 20% of total human biomass.</p>
<p>Carbon makes up <a href="https://www.pnas.org/doi/abs/10.1073/pnas.1711842115">about half</a> the dry weight of an ant. If the weight of other bodily elements was included, the total mass of the world’s ants would be higher still. </p>
<p>We also found ants are distributed unevenly on Earth’s surface. They vary sixfold between habitats and generally peak in the tropics. This underscores the importance of tropical regions in maintaining healthy ant populations.</p>
<p>Ants were also particularly abundant in forests, and surprisingly, in arid regions. But they become less common in human-made habitats. </p>
<p>Our findings come with a few caveats. For example, the sampling locations in our dataset are unevenly distributed across geographic regions. And the vast majority of samples were collected from the ground layer, meaning we have very little information about ant numbers in trees or <a href="https://www.asianscientist.com/2017/07/features/aswp2017-subterranean-ants/">underground</a>. This means our findings are somewhat incomplete. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/where-are-all-the-ants-world-first-treasure-map-reveals-hotspots-for-rare-species-188092">Where are all the ants? World-first ‘treasure map’ reveals hotspots for rare species</a>
</strong>
</em>
</p>
<hr>
<figure class="align-center ">
<img alt="thousands of ants form a line across a road" src="https://images.theconversation.com/files/485220/original/file-20220919-53704-yd22vt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/485220/original/file-20220919-53704-yd22vt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/485220/original/file-20220919-53704-yd22vt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/485220/original/file-20220919-53704-yd22vt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/485220/original/file-20220919-53704-yd22vt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/485220/original/file-20220919-53704-yd22vt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/485220/original/file-20220919-53704-yd22vt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The new research found ants are distributed unevenly on Earth’s surface.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>We all need ants</h2>
<p>Ants also provide vital “ecosystem services” for humans. For instance, a recent study <a href="https://www.theguardian.com/environment/2022/aug/17/ants-can-beat-pesticides-helping-farmers-grow-healthy-crops-study-aoe">found</a> ants can be more effective than pesticides at helping farmers produce food. </p>
<p>Ants have also developed tight interactions with other organisms – and some species cannot survive without them. </p>
<p>For example, some birds rely on ants to <a href="https://beta.nsf.gov/news/birds-follow-army-ants-find-prey">flush out</a> their prey. And thousands of plant species either <a href="https://www.kew.org/read-and-watch/ants-and-plants-a-very-natural-love-story">feed or house ants</a> in exchange for protection, or dispersal of their seeds. And many ants are predators, helping to keep populations of other insects in check.</p>
<figure class="align-center ">
<img alt="ant carries prey in jaws" src="https://images.theconversation.com/files/485170/original/file-20220918-15948-of2myk.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/485170/original/file-20220918-15948-of2myk.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/485170/original/file-20220918-15948-of2myk.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/485170/original/file-20220918-15948-of2myk.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/485170/original/file-20220918-15948-of2myk.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=504&fit=crop&dpr=1 754w, https://images.theconversation.com/files/485170/original/file-20220918-15948-of2myk.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=504&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/485170/original/file-20220918-15948-of2myk.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=504&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A purple Rhytidoponera ant carries her prey between her jaws. Many ants serve as predators that help keep populations of other insects in check.</span>
<span class="attribution"><span class="source">Francois Brassard</span></span>
</figcaption>
</figure>
<p>Alarmingly, global insect numbers are <a href="https://theconversation.com/climate-change-triggering-global-collapse-in-insect-numbers-stressed-farmland-shows-63-decline-new-research-170738#:%7E:text=Throughout%20the%20world%2C%20our%20analysis,habitat%20has%20been%20largely%20preserved">declining</a> due to threats such as habitat destruction and fragmentation, chemical use, invasive species and climate change.</p>
<p>But data on insect biodiversity is alarmingly scarce. We hope our study provides a baseline for further research to help fill this gap.</p>
<p>It’s in humanity’s interest to monitor ant populations. Counting ants is not difficult, and citizen scientists from all over the world could help investigate how these important animals are faring at a time of great environmental change.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/why-tiny-ants-have-invaded-your-house-and-what-to-do-about-it-132092">Why tiny ants have invaded your house, and what to do about it</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/190831/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Mark Wong receives funding from the Forrest Research Foundation. </span></em></p><p class="fine-print"><em><span>Benoit Guénard is an Associate Professor at The University of Hong Kong (HKU). This study was supported thanks to funding from HKU, an Early Career Scheme of the Research Grant Council of Hong Kong (# ECS-27106417), and by National Geographic.</span></em></p><p class="fine-print"><em><span>Patrick Schultheiss is a Temporary Principal Investigator at the University of Würzburg in Germany. He currently receives funding from the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) - project no. 499479766. This study was further supported by a Division of Ecology and Biodiversity Postdoctoral Fellow Research Award from the University of Hong Kong.</span></em></p><p class="fine-print"><em><span>Sabine Nooten receives funding from the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) — project No. 445715161</span></em></p><p class="fine-print"><em><span>François Brassard and Runxi Wang do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Invertebrates are “the little things that run the world”. So researchers decided to count all the ants on Earth, to help monitor how they’re coping with environmental challenges.Mark Wong, Forrest Fellow, The University of Western AustraliaBenoit Guénard, Associate professor, University of Hong KongFrançois Brassard, PhD candidate, Charles Darwin UniversityPatrick Schultheiss, Temporary Principal Investigator, Julius Maximilian University of WürzburgRunxi Wang, PhD candidate, University of Hong KongSabine Nooten, Temporary Principal Investigator, Julius Maximilian University of WürzburgLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1813872022-04-28T14:42:10Z2022-04-28T14:42:10ZForests in the tropics are critical for tackling climate change – yet the people showing how are being exploited<figure><img src="https://images.theconversation.com/files/460359/original/file-20220428-9923-spo5l2.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C3761%2C2505&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/aerial-view-ancient-tropical-forest-mist-1197808021">Tanes Ngamsom/Shutterstock</a></span></figcaption></figure><p>Nowhere is nature more vibrant than in Earth’s tropical forests. Thought to contain more than half of all <a href="https://www.science.org/doi/full/10.1126/sciadv.abc6228">plant</a> and <a href="https://www.nature.com/articles/s41586-018-0301-1">animal</a> species, the forests around Earth’s equator have sustained foragers and farmers since the earliest days of humanity. Today, their bounty underpins much of our globalised diet and holds vast potential for <a href="https://theconversation.com/dwindling-tropical-rainforests-mean-lost-medicines-yet-to-be-discovered-in-their-plants-126578">new and existing medicine</a>. Those that remain lock up <a href="https://www.nature.com/articles/s41586-020-2035-0">billions of tonnes</a> of carbon dioxide each year, providing the best natural solution for climate change. There is no credible path to net zero emissions in which tropical lands are ignored.</p>
<p>Nations are clamouring for information on how much carbon tropical forests can keep out of a rapidly warming atmosphere to help limit global warming to well below 2°C. The best way to study these forests is through long-term measurements taken in carefully defined plots, one tree at a time, year-after-year. These plots tell us what species are present and need help, which forests store the most carbon and grow fastest and which trees excel at resisting heat and producing timber.</p>
<p>Far from the laboratories and capital cities where forests are studied and legislated upon, tropical people gather the data that forms the basis of our knowledge about these vital ecosystems. Conventional wisdom might suggest that making all their data freely accessible is egalitarian. But for the people measuring tropical forest species and carbon, offering the fruits of their labour without fair investment won’t reduce inequalities – it will increase them. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/460299/original/file-20220428-12-bzy2dn.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A person in a harness ascends the trunk of a tropical tree." src="https://images.theconversation.com/files/460299/original/file-20220428-12-bzy2dn.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/460299/original/file-20220428-12-bzy2dn.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/460299/original/file-20220428-12-bzy2dn.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/460299/original/file-20220428-12-bzy2dn.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/460299/original/file-20220428-12-bzy2dn.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/460299/original/file-20220428-12-bzy2dn.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/460299/original/file-20220428-12-bzy2dn.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A Colombian colleague measures a giant Dipteryx tree in the Chocó rainforest.</span>
<span class="attribution"><span class="source">Zorayda Restrepo Correa</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>That’s because those gathering the data in tropical forests are extraordinarily disadvantaged compared to the researchers and policymakers who use it. Field workers can put their lives at risk to expand the world’s understanding of one of its best bulwarks against climate change and its biggest repository of biodiversity. For this, they receive scant protection and meagre compensation.</p>
<p>Valuing these workers is essential to make the most of what nature can offer to tackle biodiversity loss and the climate crisis. For example, tropical forests have an unparalleled ability to absorb carbon from the atmosphere. But without measuring this, the potentially massive contribution of tropical forests to slowing climate change will be overlooked, undervalued and inadequately paid for.</p>
<p>Now, 25 leading researchers in <a href="https://www.nature.com/articles/s41559-022-01738-7">tropical forest science</a> from Africa, Asia, Europe, North and South America are demanding an end to the exploitation which undermines the sustainability of forests themselves.</p>
<h2>Precarious, dangerous and underfunded</h2>
<p>Measuring the biodiversity and carbon of a single hectare of Amazon forest requires collecting and identifying <a href="https://www.pnas.org/doi/10.1073/pnas.85.1.156#:%7E:text=Contrary%20to%20accepted%20opinion%2C%20upper,soils%20on%20all%20three%20continents.">up to ten times</a> the number of tree species present in the UK’s entire 24 million hectares. The skill, risks and costs involved in gathering this information are ignored by those who expect it for free.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/460294/original/file-20220428-26-qjui0g.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two world maps separately coloured to denote national GDP and tropical forest area." src="https://images.theconversation.com/files/460294/original/file-20220428-26-qjui0g.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/460294/original/file-20220428-26-qjui0g.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=621&fit=crop&dpr=1 600w, https://images.theconversation.com/files/460294/original/file-20220428-26-qjui0g.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=621&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/460294/original/file-20220428-26-qjui0g.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=621&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/460294/original/file-20220428-26-qjui0g.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=780&fit=crop&dpr=1 754w, https://images.theconversation.com/files/460294/original/file-20220428-26-qjui0g.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=780&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/460294/original/file-20220428-26-qjui0g.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=780&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">How (a) 2008–2018 national average GDP per capita compares with (b) tropical forest area.</span>
<span class="attribution"><a class="source" href="https://www.nature.com/articles/s41559-022-01738-7">Lima et al. (2022)</a>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Fieldworkers risk their lives to measure and identify remote tropical trees. Many face the threat of kidnapping and murder, not to mention natural hazards like snake bites, floods and fires. Most long-term workers have endured infectious diseases such as malaria and typhoid, as well as dangerous transport and the risk of gender-based violence. But they may be out of work as soon as the data are collected. How many of those using their outputs to calibrate satellite instruments or write high-level reports, like <a href="https://theconversation.com/ipcc-says-the-tools-to-stop-catastrophic-climate-change-are-in-our-hands-heres-how-to-use-them-179654">the recent one</a> from the Intergovernmental Panel on Climate Change, will face similar conditions?</p>
<p>It costs an estimated <a href="https://rainfor.org/upload/publication-store/2021/ForestPlotsnet_Taking_the_pulse_of_forests_plot_networks_BiolCons_2021f.pdf">US$7 million a year</a> to measure how much carbon is sequestered by intact tropical forests. This easily exceeds piecemeal funding by a handful of charities and research councils. Because investment in field research is so inadequate, tropical nations have little idea how their forests are faring as climate change accelerates. They’re unable to say which are slowing it and lack the bargaining power to raise the finance needed to protect them.</p>
<p>Meanwhile, the US spends over US$90 million annually on its <a href="https://www.fia.fs.fed.us/library/bus-org-documents/docs/FIA%20FY2020%20Business%20Report%20-%20draft%20tables.pdf">national forest inventory</a>. Wealthy countries have a firm understanding of their forest carbon balances, and have little trouble demonstrating to the world the contributions their forests make to slowing climate change.</p>
<h2>A fair deal for field workers</h2>
<p>A different approach must put the needs of data gatherers first and demand those benefiting from their efforts contribute funding and other support. Equal collaboration should be the goal of funders, producers and users of tropical forest science alike.</p>
<figure class="align-center ">
<img alt="Students gather hold a measuring tape around a tree trunk." src="https://images.theconversation.com/files/460280/original/file-20220428-22-8vn1bs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/460280/original/file-20220428-22-8vn1bs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=449&fit=crop&dpr=1 600w, https://images.theconversation.com/files/460280/original/file-20220428-22-8vn1bs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=449&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/460280/original/file-20220428-22-8vn1bs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=449&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/460280/original/file-20220428-22-8vn1bs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=565&fit=crop&dpr=1 754w, https://images.theconversation.com/files/460280/original/file-20220428-22-8vn1bs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=565&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/460280/original/file-20220428-22-8vn1bs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=565&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Field botanist Moses Sainge trains university students in data collection, Sierra Leone.</span>
<span class="attribution"><span class="source">Moses N. Sainge</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>For that to happen, research funding must cover not only the costs of acquiring the data, but also of training and guaranteeing safe and secure employment for forest workers. Involving local communities is critical too – they often own the forests and need economic opportunities as much as anyone. After the fieldwork, there should be funding for the essential work of curating, managing and sharing the data.</p>
<p>Authors and journals who publish scientific studies on tropical forests can help by always including the people who collect the data as authors and publishing in their languages, rather than assuming English is enough.</p>
<p>Everyone could eventually benefit from the open sharing of data. After all, the tree of knowledge yields many fruits. But unless we dedicate ourselves to sustaining its roots, there will be little left to harvest.</p>
<hr>
<figure class="align-right ">
<img alt="Imagine weekly climate newsletter" src="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
</figcaption>
</figure>
<p><strong><em>Don’t have time to read about climate change as much as you’d like?</em></strong>
<br><em><a href="https://theconversation.com/uk/newsletters/imagine-57?utm_source=TCUK&utm_medium=linkback&utm_campaign=Imagine&utm_content=DontHaveTimeTop">Get a weekly roundup in your inbox instead.</a> Every Wednesday, The Conversation’s environment editor writes Imagine, a short email that goes a little deeper into just one climate issue. <a href="https://theconversation.com/uk/newsletters/imagine-57?utm_source=TCUK&utm_medium=linkback&utm_campaign=Imagine&utm_content=DontHaveTimeBottom">Join the 10,000+ readers who’ve subscribed so far.</a></em></p>
<hr><img src="https://counter.theconversation.com/content/181387/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Oliver Phillips receives funding from the UK Natural Environment Research Council, the European Research Council, the European Space Agency, the European Union and the Royal Society. </span></em></p><p class="fine-print"><em><span>Aida Cuni Sanchez receives funding from the UK Natural Environment Research Council. </span></em></p><p class="fine-print"><em><span>Renato Lima received funding from the São Paulo Research Foundation (FAPESP). </span></em></p>Tropical forests are one of humanity’s best hopes for slowing climate change.Oliver Phillips, Professor of Tropical Ecology, University of LeedsAida Cuni Sanchez, Associate Professor of Environmental Sciences, Norwegian University of Life Sciences and Honorary Research Fellow, University of YorkRenato Lima, Associate Research Scientist in Forest Ecology, Universidade de São Paulo (USP)Licensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1707382022-04-20T15:12:33Z2022-04-20T15:12:33ZClimate change triggering global collapse in insect numbers: stressed farmland shows 63% decline – new research<h2>Speed read</h2>
<ul>
<li><p>The world may be facing a devastating “hidden” collapse in insect species due to the twin threats of climate change and habitat loss.</p></li>
<li><p>UCL’s <a href="https://www.ucl.ac.uk/biosciences/gee/ucl-centre-biodiversity-and-environment-research">Centre for Biodiversity & Environment Research</a> has carried out one of the largest-ever assessments of insect declines around the world – assessing three-quarters of a million samples from around 6,000 sites.</p></li>
<li><p>The new study, published in <a href="https://www.nature.com/articles/s41586-022-04644-x">Nature</a>, finds that climate-stressed farmland possesses only half the number of insects, on average, and 25% fewer insect species than areas of natural habitat.</p></li>
<li><p>Insect declines are greatest in high-intensity farmland areas within tropical countries – where the combined effects of climate change and habitat loss are experienced most profoundly.</p></li>
<li><p>The majority of the world’s estimated 5.5 million species are thought to live in these regions – meaning the planet’s greatest abundances of insect life may be suffering collapses without us even realising.</p></li>
<li><p>Lowering the intensity of farming by using fewer chemicals, having a greater diversity of crops and preserving some natural habitat can mitigate the negative effects of habitat loss and climate change on insects.</p></li>
<li><p>Considering the choices we make as consumers – such as buying shade-grown coffee or cocoa – could also help protect insects and other creatures in the world’s most climate-vulnerable regions.</p></li>
</ul>
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<h2>Long read</h2>
<p>Insects are critical to the future of our planet. They help to keep pest species under control and break down dead material to release nutrients into the soil. Flying insects are also key pollinators of many major food crops, including fruits, spices and – importantly for chocolate lovers – cocoa.</p>
<p>The growing number of reports suggesting insect numbers are in steep decline is therefore of urgent concern. Loss of insect biodiversity could put these vital ecological functions at risk, threatening human livelihoods and food security in the process. Yet across large swathes of the world, there are gaps in our knowledge about the true scale and nature of insect declines.</p>
<p>Most of what we do know comes from data collected in the planet’s more temperate regions, especially Europe and North America. For example, widespread losses of pollinators have been <a href="https://www.nature.com/articles/s41467-019-08974-9">identified in Great Britain</a>, butterflies have experienced declines in numbers of between 30 and 50% <a href="https://www.pnas.org/doi/10.1073/pnas.2002551117">across Europe</a>, and a 76% reduction in the biomass of flying insects has been <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0185809">reported in Germany</a>.</p>
<p>Information on insect species numbers and their abundance in the tropics (the regions either side of the Equator including the Amazon rainforest, all of Brazil, and much of Africa, India and Southeast Asia) is far more scarce. Yet the majority of the world’s estimated 5.5 million insect species are thought to <a href="https://www.annualreviews.org/doi/abs/10.1146/annurev-ento-020117-043348">live in these tropical regions</a> – meaning the planet’s greatest abundances of insect life may be suffering calamitous collapses without us even realising.</p>
<p>The largest of the 29 major insect groups are butterflies/moths, beetles, bees/wasps/ants and flies. Each of these groups is thought to contain more than one million species. Not only is it near-impossible to monitor such a vast number, but as many as 80% of insects may not have been discovered yet – of which many are tropical species.</p>
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<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/288776/original/file-20190820-170910-8bv1s7.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/288776/original/file-20190820-170910-8bv1s7.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/288776/original/file-20190820-170910-8bv1s7.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/288776/original/file-20190820-170910-8bv1s7.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/288776/original/file-20190820-170910-8bv1s7.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/288776/original/file-20190820-170910-8bv1s7.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/288776/original/file-20190820-170910-8bv1s7.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p><strong><em>This story is part of Conversation Insights</em></strong>
<br><em>The Insights team generates <a href="https://theconversation.com/uk/topics/insights-series-71218">long-form journalism</a> and is working with academics from different backgrounds who have been engaged in projects to tackle societal and scientific challenges.</em></p>
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<p>Responding to these knowledge gaps, researchers at UCL’s <a href="https://www.ucl.ac.uk/biosciences/gee/ucl-centre-biodiversity-and-environment-research">Centre for Biodiversity and Environment Research</a> have conducted one of the largest-ever assessments of insect biodiversity change. Some three-quarters of a million samples from around 6,000 sites worldwide were analysed in our study, adding up to nearly 20,000 different species in all.</p>
<p>Insects are facing an unprecedented threat due to the “twin horsemen” of climate change and habitat loss. We sought to understand how insect biodiversity is being affected in areas that experience both these challenges most severely. We know they do not work in isolation: habitat loss can add to the effects of climate change by limiting available shade, for example, leading to even warmer temperatures in these vulnerable areas.</p>
<p>For the first time, we were able to include these important interactions in our global biodiversity modelling. Our findings, <a href="https://www.nature.com/articles/s41586-022-04644-x">published today in Nature</a>, reveal that insect declines are greatest in farmland areas within tropical countries – where the combined effects of climate change and habitat loss are experienced most profoundly.</p>
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<strong>
Read more:
<a href="https://theconversation.com/biodiversity-why-foods-grown-in-warm-climates-could-be-doing-the-most-damage-to-wildlife-147584">Biodiversity: why foods grown in warm climates could be doing the most damage to wildlife</a>
</strong>
</em>
</p>
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<p>We compared high-intensity farmland sites where high levels of warming have occurred with (related) areas of natural habitat that are little-affected by climate change. The farmland sites possess only half the number of insects, on average, and more than 25% fewer insect species. Throughout the world, our analysis also shows that farmland in climate-stressed areas where most nearby natural habitat has been removed has lost 63% of its insects, on average, compared with as little as 7% for farmland where the nearby natural habitat has been largely preserved.</p>
<p>Areas our study highlights as particularly at risk include Indonesia and Brazil, where many crops depend on insects for pollination and other vital ecosystem services. This has serious implications for local farmers and the wider food chain in these climatically and economically vulnerable areas.</p>
<h2>Cocoa, midges and deforestation</h2>
<p>Eighty-seven of the world’s major crops are thought to be fully or partially <a href="http://www.royalsocietypublishing.org/doi/10.1098/rspb.2006.3721">dependent on insect pollinators</a>, of which most tend to be grown in the tropics. Cocoa, for example, is primarily pollinated by midges, a group of flies infamous for bedevilling camping trips in Scotland and other parts of the northern hemisphere. In fact, midges play a vital and under-appreciated role in pollinating the cocoa needed to make chocolate.</p>
<p>The majority of cocoa production takes place in <a href="https://www.fao.org/faostat/en/#data/QCL/visualize">Indonesia, Côte d’Ivoire and Ghana</a>. In Indonesia alone, the export of cocoa beans is valued at around <a href="https://www.statista.com/statistics/1228480/indonesia-value-of-cocoa-bean-exports/">US$75 million per year</a>. Most cocoa production is carried out by <a href="https://www.indonesia-investments.com/business/commodities/cocoa/item241">smallholders rather than big plantation owners</a>, and many farmers are dependent on this crop for their livelihoods. While it is critical to understand whether insect losses will make things worse for cocoa and its farmers, we have very little knowledge of the state of insect biodiversity in tropical countries such as Indonesia.</p>
<figure class="align-center ">
<img alt="Cocoa farmer in Indonesia" src="https://images.theconversation.com/files/458649/original/file-20220419-20-etyld0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/458649/original/file-20220419-20-etyld0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/458649/original/file-20220419-20-etyld0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/458649/original/file-20220419-20-etyld0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/458649/original/file-20220419-20-etyld0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/458649/original/file-20220419-20-etyld0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/458649/original/file-20220419-20-etyld0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Cocoa production in Indonesia is carried out by smallholders whose livelihoods may be hit by insect decline.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/gorontalo-indonesia-may-1st-2019-farmers-1898867581">Shutterstock</a></span>
</figcaption>
</figure>
<p>Cocoa production in the region is already being <a href="https://economictimes.indiatimes.com/news/economy/agriculture/cocoa-output-to-plunge-in-the-coming-season/articleshow/65884243.cms">stressed by adverse weather events</a> that may be linked to climate change. Warming temperatures and changing rainfall patterns are implicated in changes in the growth, pollination and <a href="http://j-tropical-crops.com/index.php/agro/article/view/140/77">bean production</a> of cocoa plants.</p>
<p>Agriculture is one of the major industries for the people of Indonesia, particularly in rural regions, with large areas being cleared for the <a href="https://iopscience.iop.org/article/10.1088/1748-9326/aaf6db/meta">production of key crops</a>, also including palm oil. This has resulted in deforestation of extensive areas of rainforest, increasing the risk to many rare and endangered species <a href="https://www.sciencedirect.com/science/article/pii/S0960982218305542">such as the orangutan</a>, as well as less well-known species including many insects. </p>
<p>Tropical regions are under considerable threat, primarily as a result of agricultural expansion – often to meet increasing demand from countries outside the tropics. International trade has been shown to be a major driver of deforestation in these regions, with forests in Southeast Asia, East and West Africa and the Amazon <a href="https://www.nature.com/articles/s41559-021-01417-z">particularly vulnerable</a>. Brazil’s and Indonesia’s high levels of deforestation are attributed to the production of commodities for export including soybean, coffee, palm oil – and cocoa.</p>
<h2>The threat of climate change</h2>
<p>Habitat loss is known to be a key threat to biodiversity, yet its impact on insects is still under-studied, and assessments of tropical species tend to be very rare. One study found that forest-dependent orchid bees in Brazil have declined in abundance <a href="https://www.scielo.br/j/bjb/a/y5K3nkpk3BPyFmth6JBVPdD/?lang=en&format=html">by around 50%</a> (although it only sampled their numbers at two time points). Orchid bees, found only in the Americas, are important pollinators of orchid flowers, with some plants being entirely dependent on this insect for their pollination. </p>
<figure class="align-center ">
<img alt="Ethiopian farmland" src="https://images.theconversation.com/files/449766/original/file-20220303-8354-ku72l1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/449766/original/file-20220303-8354-ku72l1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/449766/original/file-20220303-8354-ku72l1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/449766/original/file-20220303-8354-ku72l1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/449766/original/file-20220303-8354-ku72l1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/449766/original/file-20220303-8354-ku72l1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/449766/original/file-20220303-8354-ku72l1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Example of a farmland system in the tropics, in Ethiopia.</span>
<span class="attribution"><span class="source">Tim Newbold</span></span>
</figcaption>
</figure>
<p>Adding to the challenges of deforestation and other, longer-term habitat changes, is climate change. This fast-emerging threat to insect biodiversity has already been implicated in <a href="https://www.pnas.org/doi/10.1073/pnas.2002546117">declines of moths in Costa Rica</a> and <a href="https://www.science.org/doi/10.1126/science.aax8591">bumblebees in Europe and North America</a>. Rising temperatures and increasing frequency of extreme weather events, such as droughts, are just two manifestations known to be having a harmful impact on many insect species.</p>
<p>It is predicted that climate change will have a particularly big impact in the planet’s tropical regions. Temperatures in the tropics are naturally quite stable, so species aren’t used to coping with the fast changes in temperature <a href="https://www.pnas.org/doi/10.1073/pnas.0709472105">we are seeing with climate change</a>. Again, though, our ability to understand how this is affecting tropical insects is hampered by a lack of data for these regions. Almost all of the available data comes from only a few very well-studied groups of insects – in particular, butterflies, moths and bees – while many other groups receive very little attention. Despite a big increase in studies of insect biodiversity change, there is still much we don’t know.</p>
<h2>Insects normally missed</h2>
<p>To help address this knowledge gap, our study has assessed three-quarters of a million samples of insects from all over the world. Of the 6,000 sites included, almost one third are from tropical locations. Our samples of nearly 20,000 different insect species include beetles, bees, wasps, ants, butterflies, moths, flies, bugs, dragonflies and other, less well-known groups.</p>
<p>This was made possible through the use of <a href="https://www.predicts.org.uk/pages/outputs.html">PREDICTS</a>, a biodiversity database which brings together millions of samples collected by researchers all over the world. PREDICTS records biodiversity in natural habitats and also in areas used by humans for growing crops, among other purposes. It is one of very few global databases that allow us to study biodiversity changes across the whole world.</p>
<figure class="align-center ">
<img alt="Two colourful butterflies photographed near Iquitos, Peru" src="https://images.theconversation.com/files/458653/original/file-20220419-19-olrvdm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/458653/original/file-20220419-19-olrvdm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/458653/original/file-20220419-19-olrvdm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/458653/original/file-20220419-19-olrvdm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/458653/original/file-20220419-19-olrvdm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/458653/original/file-20220419-19-olrvdm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/458653/original/file-20220419-19-olrvdm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Almost all insect data comes from a few very well-studied groups – in particular, butterflies, moths and bees.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/two-colorful-butterflies-eating-food-near-347296631">Shutterstock</a></span>
</figcaption>
</figure>
<p>While our 20,000-strong sample represents only a fraction of the vast diversity of insect species, it is still a sample from more sites than have ever been studied before. We were particularly interested in using it to understand how habitat loss and climate change play off each other to affect insect biodiversity, and were able to include these interactions in our models for the first time.</p>
<p>These twin conditions are found most profoundly in farmland in tropical countries. And our results demonstrate that farmland in these regions has typically lost a lot of insect biodiversity, relative to areas of primary vegetation. This highlights that climate change may present a major threat to food security not only by directly impacting crops, but also through losses of pollinators and other important insects.</p>
<p>As climate change accelerates, the ability to grow cocoa and other crops in their current geographical ranges is already becoming more uncertain, threatening local livelihoods and reducing the availability of these crops for consumers all over the world. The insect losses our study highlights are only likely to add to this risk. Indeed, threats to food security due to the loss of insect biodiversity are already being seen in both temperate and tropical regions: for example, evidence of reduced yields due to a lack of pollinators has been reported for cherry, apple and blueberry <a href="https://royalsocietypublishing.org/doi/abs/10.1098/rspb.2020.0922">production in the US</a>.</p>
<p>In some parts of the world, farmers are resorting to hand-pollination techniques, where the flowers of crops are pollinated using a brush. Hand pollination is <a href="https://www.sciencedirect.com/science/article/pii/S1439179121001286">used for cocoa in a number of countries</a>, including Ghana and Indonesia. These techniques can help to maintain or increase yield, but come at a high labour cost.</p>
<h2>Reducing the declines</h2>
<p>Our study also highlights changes that could help to reduce insect declines. Lowering the intensity of farming – for example, by using fewer chemicals and having a greater diversity of crops – mitigates some of the negative effects of habitat loss and climate change. In particular, we show that preserving natural habitat within farmed landscapes really helps insects. Where farmland in climate-stressed areas with its natural habitat largely removed shows insect reductions of 63%, on average, this number drops to as little as 7% where three-quarters of the nearby natural habitat has been preserved.</p>
<p>For insects living on farmland, natural habitat patches act as an alternative source of food, nesting sites and places to shelter from high temperatures. This offers hope that even while the planet continues to warm, there are options that will reduce some of the impacts on insect biodiversity.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/458655/original/file-20220419-24-uo4d7y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Banded demoiselle damselfly" src="https://images.theconversation.com/files/458655/original/file-20220419-24-uo4d7y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/458655/original/file-20220419-24-uo4d7y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/458655/original/file-20220419-24-uo4d7y.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/458655/original/file-20220419-24-uo4d7y.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/458655/original/file-20220419-24-uo4d7y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/458655/original/file-20220419-24-uo4d7y.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/458655/original/file-20220419-24-uo4d7y.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Not all species are struggling: one UK study shows an increase in freshwater insects such as the damselfly.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/banded-demoiselle-damselfly-uk-1278267334">Shutterstock</a></span>
</figcaption>
</figure>
<p>Indeed, natural habitat availability has already been shown, at smaller scales, to have a positive impact within agricultural systems in particular. For Indonesian cocoa, increasing the amount of natural habitat has been found to boost numbers of key insects <a href="https://www.sciencedirect.com/science/article/pii/S0006320721001580">including pollinators</a>. Our new study shows, however, that the benefits of this intervention are only found in less-intensive farming systems. This might mean reducing the level of inputs such as fertilisers and insecticides that are applied, or increasing crop diversity to ensure the benefits of nearby natural habitat can be felt.</p>
<p>It’s also important to note that not all species are enduring a hard time as a result of recent pressures. For example, recent work looking at UK insects has shown that while some groups have declined, others, including freshwater insects, have <a href="https://www.nature.com/articles/s41559-020-1111-z">increased</a> in <a href="https://theconversation.com/meet-the-insects-that-are-defying-the-plunge-in-biodiversity-new-findings-131846">recent years</a>. Another <a href="https://www.science.org/doi/10.1126/science.aax9931">study</a> looking at worldwide insect trends also found increases in the numbers of freshwater insects. However, many of these positive trends have been reported in non-tropical regions such as the UK and Europe, where a lot has been done, for example, to improve the water quality of rivers in recent years, following past degradation.</p>
<h2>Making a difference</h2>
<p>The COVID-19 lockdowns prompted many of us to reconnect with the flora and fauna around us. In the UK, the warm spring weather of 2020 saw an apparent increase in the abundance of insects in the UK countryside. However, this spike was probably temporary, and something of an anomaly set against the bigger picture worldwide. </p>
<p>To support more insect biodiversity in our local environments, we can plant diverse gardens to attract insects, reduce the amount of pesticides used in gardens and allotments, and reduce how often we mow our lawns. (In the UK, you could consider joining the <a href="https://www.plantlife.org.uk/uk/discover-wild-plants-nature/no-mow-may">No Mow May challenge</a>.) However, it is not just locally that we can make a difference. Considering the choices we make as consumers could help protect insects and other creatures in the tropics. For example, buying shade-grown coffee or cocoa will ensure a lesser impact on biodiversity than crops grown in the open.</p>
<p>Meanwhile, governments and other public and private organisations should consider more carefully the impact their actions and policies are having on insects. This could range from the proper consideration of biodiversity within trade policies and agreements, to ensuring that products are not sourced from areas associated with high deforestation rates.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/covid-19-shutdowns-will-give-wildlife-only-short-term-relief-from-climate-change-and-other-threats-139193">COVID-19 shutdowns will give wildlife only short-term relief from climate change and other threats</a>
</strong>
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<p>And then there’s the data issue. We are increasingly recognising the importance of insects for human health and wellbeing, and their key role in global food production systems. Safeguarding the environment to protect insects into the future will have big benefits for human societies around the world. However, none of this is possible without good data.</p>
<p>One important step towards a better understanding of insect biodiversity change is to bring together and assess the data that is already available. A new project of which we are part, <a href="https://glitrs.ceh.ac.uk/">GLiTRS (GLobal Insect Threat-Response Synthesis)</a>, is doing this by combining the work of leading experts from a range of institutions and ecological disciplines, including data analysts. The project will then assess how different insect groups are responding to certain threats. </p>
<p>Understanding what is causing insect declines is key for preventing even greater losses in the future, and for safeguarding the valuable functions that insects perform. Climate change and biodiversity loss are major global crises that are <a href="https://royalsociety.org/topics-policy/projects/biodiversity-climate-change-interlinkages/">two sides of the same coin</a>. Their combined effects on food production mean the health, wellbeing and livelihoods of many people in the tropics and beyond are hanging in the balance. Insect biodiversity losses are a crucial, but as yet understudied, part of this story.</p>
<hr>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/313478/original/file-20200204-41481-1n8vco4.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/313478/original/file-20200204-41481-1n8vco4.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=112&fit=crop&dpr=1 600w, https://images.theconversation.com/files/313478/original/file-20200204-41481-1n8vco4.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=112&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/313478/original/file-20200204-41481-1n8vco4.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=112&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/313478/original/file-20200204-41481-1n8vco4.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=140&fit=crop&dpr=1 754w, https://images.theconversation.com/files/313478/original/file-20200204-41481-1n8vco4.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=140&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/313478/original/file-20200204-41481-1n8vco4.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=140&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
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<p class="fine-print"><em><span>Tim Newbold receives funding from the Royal Society, UK Natural Environment Research Council grants NE/R010811/1 and NE/V006533/1, ESRC grants ES/P011306/1 and ES/S008160/1, and from the Leverhulme Trust. </span></em></p><p class="fine-print"><em><span>Charlie Outhwaite received funding from UK Natural Environment Research Council grants NE/R010811/1 and NE/V006533/1 for this work.</span></em></p>Insect numbers and species decline steeply where agriculture and habitat loss coincide. Preserving natural habitat can reduce losses up to nine-foldTim Newbold, Senior Research Fellow, Centre for Biodiversity and Environment, UCLCharlie Outhwaite, Postdoctoral Researcher in Biodiversity Change, UCLLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1635842021-11-15T19:10:45Z2021-11-15T19:10:45ZDeforestation can raise local temperatures by up to 4.5°C – and heat untouched areas 6km away<figure><img src="https://images.theconversation.com/files/431857/original/file-20211115-13-69dhu5.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C5472%2C3637&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>Forests directly cool the planet, like natural evaporative air conditioners. So what happens when you cut them down? </p>
<p>In tropical countries such as Indonesia, Brazil and the Congo, rapid deforestation <a href="https://www.nature.com/articles/nclimate3250">may have accounted for</a> up to 75% of the observed surface warming between 1950 and 2010. <a href="https://iopscience.iop.org/article/10.1088/1748-9326/ac2fdc">Our new research</a> took a closer look at this phenomenon. </p>
<p>Using satellite data over Indonesia, Malaysia and Papua New Guinea, we found deforestation can heat a local area by as much as 4.5°C, and can even raise temperatures in undisturbed forests up to 6km away. </p>
<p>More than 40% of the world’s population live in the tropics and, under climate change, rising heat and humidity could push them into <a href="https://www.nature.com/articles/s41561-021-00695-3">lethal conditions</a>. Keeping forests intact is vital to protect those who live in and around them as the planet warms. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/431859/original/file-20211115-13-g3akke.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/431859/original/file-20211115-13-g3akke.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/431859/original/file-20211115-13-g3akke.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/431859/original/file-20211115-13-g3akke.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/431859/original/file-20211115-13-g3akke.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/431859/original/file-20211115-13-g3akke.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/431859/original/file-20211115-13-g3akke.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/431859/original/file-20211115-13-g3akke.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Trees provide shade, habitat, and regulate the supply of clean water.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>Deforestation hot spots</h2>
<p>At the recent climate change summit in Glasgow, world leaders representing 85% of Earth’s remaining forests committed to ending, and reversing, <a href="https://ukcop26.org/glasgow-leaders-declaration-on-forests-and-land-use/">deforestation by 2030</a>. </p>
<p>This is a crucial measure in our fight to stop the planet warming beyond the internationally agreed limit of 1.5°C, because forests store vast amounts of carbon. Deforestation releases this carbon – <a href="https://royalsocietypublishing.org/doi/full/10.1098/rstb.2019.0120">approximately 5.2</a> billion tonnes of carbon dioxide per year – back into the atmosphere. This accounts for nearly 10% of the global emissions from 2009-2016. </p>
<p>Deforestation is <a href="https://www.science.org/doi/10.1126/sciadv.aax8574">particularly prevalent</a> in Southeast Asia. <a href="https://data.globalforestwatch.org/documents/14228e6347c44f5691572169e9e107ad/explore">We calculate</a> that between 2000 and 2019, Indonesia lost 17% of its forested area (26.8 million hectares of land), and Malaysia 28% of its forest cover (8.12 million hectares). Others in the region, such as Papua New Guinea, are considered “<a href="https://wwf.panda.org/discover/our_focus/forests_practice/deforestation_fronts_/">deforestation hot spots</a>”, as they’re at high risk of losing their forest cover in the coming decade. </p>
<p>Forests in this region are cut down for a variety of reasons, including for expanding palm oil and timber plantations, logging, mining and small-scale farms.
And these new types of land uses produce different spatial patterns of forest loss, which we can see and measure using satellites. </p>
<h2>What we found</h2>
<p>We already know forests cool the climate directly, and losing forest causes local temperatures to rise. But we wanted to learn whether the different patterns of forest loss influenced how much temperatures increased by, and how far warming spread from the deforested site into neighbouring, unchanged areas.</p>
<p>To find out, <a href="https://iopscience.iop.org/article/10.1088/1748-9326/ac2fdc">we used</a> satellite images that measure the temperature of the land surface. As the illustration below shows, we measured this by averaging forest loss in rings of different widths and radius, and looking at the average temperature change of the forest inside the ring. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/431019/original/file-20211109-27-mpcx2l.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Illustration of how temperature changes due to forest loss." src="https://images.theconversation.com/files/431019/original/file-20211109-27-mpcx2l.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/431019/original/file-20211109-27-mpcx2l.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/431019/original/file-20211109-27-mpcx2l.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/431019/original/file-20211109-27-mpcx2l.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/431019/original/file-20211109-27-mpcx2l.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=425&fit=crop&dpr=1 754w, https://images.theconversation.com/files/431019/original/file-20211109-27-mpcx2l.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=425&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/431019/original/file-20211109-27-mpcx2l.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=425&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">How forest clearing near an unchanged area causes temperatures to rise.</span>
</figcaption>
</figure>
<p>For example, if you consider a circle of forest that’s 4km wide, and there’s a completely deforested, 2km-wide ring around it, the inner circle would warm on average by 1.2°C. </p>
<p>The closer the forest loss, the higher the warming. If the ring was 1-2km away, the circle would warm by 3.1°C, while at 4-6km away, it’s 0.75°C.</p>
<p>These might not sound like big increases in temperature, but global studies show <a href="https://www.pnas.org/content/114/35/9326.short">for each 1°C increase in temperature</a>, yields of major crops would decline by around 3-7%. Retaining forest within 1km of agricultural land in Southeast Asia could therefore avoid crop losses of 10-20%.</p>
<p>These estimates are conservative, because we only measured the effect of forest loss on average yearly temperatures. But another important factor is that higher average temperatures <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2011JD016382">usually create</a> higher temperature extremes, like those during heatwaves. And those really high temperatures in heatwaves are what put people and crops at most risk. </p>
<p>Of course, forests aren’t normally cut down in rings. This analysis was designed to exclude other causes of temperature change, putting the effect of non-local forest loss in focus.</p>
<h2>Why is this happening?</h2>
<p>Forests cool the land because trees draw water from the soil to their leaves, where it then evaporates. The energy needed to evaporate the water comes from sunshine and heat in the air, the same reason you feel colder when you get out of a pool with water on your skin. </p>
<p>A single tree in a tropical forest can cause <a href="https://www.sciencedirect.com/science/article/pii/S0959378017300134">local surface cooling equivalent</a> to 70 kilowatt hours for every 100 litres of water used from the soil — as much cooling as two household air conditioners. </p>
<p>Forests are particularly good at cooling the land because their canopies have large surface area, which can evaporate a lot of water. When forests in tropical regions are cut down, this evaporative cooling stops, and the land surface warms up.</p>
<p>This is not news to the people of Borneo. In 2018, researchers surveyed <a href="https://www.sciencedirect.com/science/article/pii/S0959378017314188">people in 477 villages</a>, and found they’re well aware nearby forest loss has caused them to live with hotter temperatures. When asked why forests were important to their health and the health of their families, the ability for trees to regulate temperature was the most frequent response.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/431029/original/file-20211109-13-18wfaj.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Logging road" src="https://images.theconversation.com/files/431029/original/file-20211109-13-18wfaj.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/431029/original/file-20211109-13-18wfaj.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/431029/original/file-20211109-13-18wfaj.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/431029/original/file-20211109-13-18wfaj.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/431029/original/file-20211109-13-18wfaj.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/431029/original/file-20211109-13-18wfaj.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/431029/original/file-20211109-13-18wfaj.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A logging road in East Kalimantan, Bornea: logged forest on the left, virgin/primary forest on the right.</span>
<span class="attribution"><a class="source" href="https://upload.wikimedia.org/wikipedia/commons/a/ab/Logging_road_East_Kalimantan_2005.jpg">Aidenvironment, 2005/Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<h2>A climate change double whammy</h2>
<p>In many parts of the world, including the tropics and Australia, expanding farmland is a major reason for cutting down forest. But given hotter temperatures also reduce the productivity of farms, conserving forests might prove a better strategy for food security and for the livelihoods of farmers. </p>
<p>If forests must be removed, there may be ways to avoid the worst possible temperature increases. For example, we found that keeping at least 10% of forest cover helped reduce the associated warming by an average of 0.2°C. </p>
<p>Similarly, temperatures did not increase as much when the area of forest loss was smaller. This means if deforestation occurs in smaller, discontinuous blocks rather than uniformly, then the temperature impacts will be less severe. </p>
<p>To help share these findings, <a href="https://treeheat.azurewebsites.net">we’ve built a web mapping tool</a> that lets users explore the effects of different patterns and areas of forest loss on local temperatures in maritime South East Asia. It helps show why protecting forests in the tropics offers a climate change double whammy – lowering carbon dioxide emissions and local temperatures together.</p><img src="https://counter.theconversation.com/content/163584/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Sally Thompson receives funding from the US National Science Foundation, the Western Australian Department of Water and Environmental Regulation, the Western Australian Department of Biodiversity, Conservation and Attractions, and the Australian Research Council. The research described in this article was funded by the National Geographic Society through the "AI for Earth" grant program. </span></em></p><p class="fine-print"><em><span>Débora Corrêa receives funding from the Australian Research Council via the Discovery Project DP200102961 and the Centre for Transforming Maintenance through Data Science (IC180100030). The research described in this article was funded by the National Geographic Society through the "AI for Earth" grant program. Sheis affiliated with de Department of Mathematics and Statistics at the University of Western Australia and the ARC Industrial Transformation Training Centre (Transforming Maintenance through Data Science), also at the University of Western Australia. </span></em></p><p class="fine-print"><em><span>John Duncan receives funding from the British Council COP26 Seasons Programme, the Australian Urban Research Infrastructure Network, and the research described in this article was funded by the National Geographic Society through the "AI for Earth" grant program. </span></em></p><p class="fine-print"><em><span>Octavia Crompton receives funding from the US National Science Foundation (under the BSF-NSF joint program, the NSF EAR Program and the NSF Postdoctoral Fellowship), and the National Geographic Society's AI for Earth program which funded the research discussed in the article.
</span></em></p>A single tree in a tropical forest has the same cooling effect as two air conditioners. Imagine how hot it gets when a whole forest is felled.Sally Thompson, Associate professor, The University of Western AustraliaDébora Corrêa, Research fellow, The University of Western AustraliaJohn Duncan, Research fellow, The University of Western AustraliaOctavia Crompton, Postdoctoral researcher, Pratt School of Engineering, Duke UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1626262021-06-16T13:46:29Z2021-06-16T13:46:29ZInsect population collapse: new evidence links it to dams<figure><img src="https://images.theconversation.com/files/406156/original/file-20210614-77865-12tozcw.jpg?ixlib=rb-1.1.0&rect=2%2C0%2C1914%2C1279&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Over 40% of all insects, like this tropical dragonfly, are in decline</span> <span class="attribution"><a class="source" href="https://pixabay.com/photos/dragonfly-top-view-colorful-4473030/">Scottslm/Pixasbay</a></span></figcaption></figure><p>Insects are the most numerous group of animals on the planet. There are an estimated <a href="https://www.annualreviews.org/doi/10.1146/annurev-ento-020117-043348">5.5 million</a> species, 80% of which remain to be discovered. Yet insects are experiencing steep, widespread declines across the world: a “<a href="https://www.pnas.org/content/118/2/e2023989118">death by a thousand cuts</a>” because of human activity. </p>
<hr>
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<p><em>You can listen to more articles from The Conversation, narrated by Noa, <a href="https://theconversation.com/uk/topics/audio-narrated-99682">here</a>.</em></p>
<hr>
<p>Insects perform almost every role imaginable in an ecosystem, including pollinating crops, keeping pests under control, and acting as food for other animals. The potential consequences of their decline are so dire that it has been dubbed the “<a href="https://theconversation.com/is-an-insect-apocalypse-happening-how-would-we-know-113170">insect apocalypse</a>”.</p>
<p>Following the flurry of attention this impending environmental catastrophe generated, a more <a href="https://www.bbc.co.uk/news/science-environment-52399373">complex picture</a> has emerged – with one gap in our understanding glaringly clear. Despite tropical and subtropical regions housing an <a href="https://www.annualreviews.org/doi/10.1146/annurev-ento-020117-043348">estimated 85%</a> of Earth’s insects, what is happening in those regions is critically understudied.</p>
<h2>Dams and declines</h2>
<p>Understanding insect decline requires long-term datasets, which are rare, especially from the global south. In <a href="https://royalsocietypublishing.org/doi/abs/10.1098/rsbl.2021.0137?af=R">our new study</a>, we present one of the most comprehensive known datasets of subtropical freshwater insects, spanning 20 years. What we found were pervasive declines in insect numbers across all examined aquatic insect groups, including midges, mayflies and dragonflies. </p>
<p>Declines occurred in channels, lakes, rivers and backwaters across one of South America’s largest freshwater systems, the <a href="https://earthobservatory.nasa.gov/images/50385/parana-river-floodplain-northern-argentina">Paraná River</a> floodplain. In parallel, we found that numbers of invasive fish increased and water chemistry became more imbalanced – environmental changes all linked to the construction of dams.</p>
<figure class="align-center ">
<img alt="A river is bisected by a concrete dam" src="https://images.theconversation.com/files/406178/original/file-20210614-79011-55vy4n.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/406178/original/file-20210614-79011-55vy4n.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=381&fit=crop&dpr=1 600w, https://images.theconversation.com/files/406178/original/file-20210614-79011-55vy4n.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=381&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/406178/original/file-20210614-79011-55vy4n.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=381&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/406178/original/file-20210614-79011-55vy4n.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=479&fit=crop&dpr=1 754w, https://images.theconversation.com/files/406178/original/file-20210614-79011-55vy4n.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=479&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/406178/original/file-20210614-79011-55vy4n.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=479&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Itaipu Dam, on the Paraná River.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Itaipu_geral.jpg">Jonas de Carvalho/Flickr</a></span>
</figcaption>
</figure>
<p>There are <a href="http://repositorio.uem.br:8080/jspui/handle/1/5328">over 130 dams</a> along the Paraná and its tributaries. The most significant is Itaipu, the second largest <a href="https://www.power-technology.com/projects/itaipu-hydroelectric/">hydroelectric plant</a> in the world. Situated in Brazil and Paraguay, its reservoir is so large that it submerged one of Earth’s largest waterfalls, Guaíra Falls, as it filled. The removal of such a natural geographic barrier between the Lower and Upper Paraná River has led to <a href="https://www.scielo.br/j/ni/a/h6d5H89THSvgQbJ3DRSgnsf/?lang=en">mass invasions</a> of fish: many of them predators of insects. </p>
<p>At the same time, dams block the flow of sediment and nutrients, disrupting the water chemistry and making the water more transparent. Most aquatic insects are dark or mottled for camouflage in murky water. The increased water transparency weakened their ability to hide, making them even more vulnerable to being eaten by the invading fish.</p>
<figure class="align-center ">
<img alt="A mosquito sits on a green stem" src="https://images.theconversation.com/files/406159/original/file-20210614-73475-1v5jzac.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/406159/original/file-20210614-73475-1v5jzac.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/406159/original/file-20210614-73475-1v5jzac.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/406159/original/file-20210614-73475-1v5jzac.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/406159/original/file-20210614-73475-1v5jzac.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/406159/original/file-20210614-73475-1v5jzac.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/406159/original/file-20210614-73475-1v5jzac.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Some flying insects such as midges have aquatic larvae, which fare worse in dammed rivers.</span>
<span class="attribution"><a class="source" href="https://pixabay.com/photos/chironomid-mosquito-insect-nature-2389699/">Kathy2408/Pixabay</a></span>
</figcaption>
</figure>
<p><a href="https://www.scielo.br/j/ni/a/h6d5H89THSvgQbJ3DRSgnsf/?lang=en">Around 70%</a> of Brazil’s electricity comes from hydropower, and hydroelectric dams will be essential in the transition away from fossil fuels. Nevertheless, damming can have severe environmental and social impacts. Our study shows that the <a href="https://theconversation.com/belo-monte-there-is-nothing-green-or-sustainable-about-these-mega-dams-98025">negative consequences</a> of dams can occur long after the forests have been flooded and local communities dislocated.</p>
<h2>Tropical data shortfall</h2>
<p>While the tropics and subtropics are the most biodiverse regions on the planet, they are also among the most <a href="https://www.pnas.org/content/118/2/e2002548117">threatened</a>. Their bountiful natural resources are under immense pressure to provide food, water and energy for some of the planet’s fastest growing human populations and developing economies. </p>
<p>Despite this, the logistical challenges of studying insects in such a biodiverse region, combined with continued historical <a href="https://journals.sagepub.com/doi/full/10.1177/194008290800100202">inequality</a> around where monitoring is conducted, means that the tropics remain <a href="https://science.sciencemag.org/content/368/6489/417.abstract">underrepresented</a> in studies on insect decline.</p>
<figure class="align-center ">
<img alt="A cloud of flying insects against a sunset" src="https://images.theconversation.com/files/406161/original/file-20210614-47555-9tooix.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/406161/original/file-20210614-47555-9tooix.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/406161/original/file-20210614-47555-9tooix.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/406161/original/file-20210614-47555-9tooix.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/406161/original/file-20210614-47555-9tooix.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/406161/original/file-20210614-47555-9tooix.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/406161/original/file-20210614-47555-9tooix.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Insect declines are particularly understudied in tropical and subtropical zones.</span>
<span class="attribution"><a class="source" href="https://pixabay.com/photos/dance-schools-mosquitoes-mass-1837658/">Hans/Pixabay</a></span>
</figcaption>
</figure>
<p>The lack of long-term datasets from the tropics and subtropics can skew the already complicated picture of how insect declines are occurring across the planet. One of the most <a href="https://science.sciencemag.org/content/368/6489/417.abstract">comprehensive studies</a> to date on global insect decline compared 166 surveys of over ten years across five continents. </p>
<p>It found land-based insects were indeed declining, but water-based insects were on the increase. However, of the 68 freshwater insect datasets in their analysis, only 7% came from the tropics. This apparent success is skewed by an overabundance of studies from Europe and North America, where increasing water quality and effective policies have boosted aquatic insect numbers.</p>
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<strong>
Read more:
<a href="https://theconversation.com/meet-the-insects-that-are-defying-the-plunge-in-biodiversity-new-findings-131846">Meet the insects that are defying the plunge in biodiversity – new findings</a>
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<p>Our results contradict the conclusions of this research. Aquatic insects are on the decline in the Paraná River system, which drains a significant proportion of southern South America -– highlighting the importance of better tropical data. Tropical and subtropical aquatic insects may be more at risk from human activity than their counterparts in more northern regions. Freshwater regions are among the most <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/j.1365-2427.2009.02395.x">threatened</a> ecosystems in the world, and must be a target for global <a href="https://www.wwf.org.uk/where-we-work/rivers-and-wetlands">conservation efforts</a>. </p>
<p>Successes for aquatic insect conservation in some parts of the world should be celebrated – but without obscuring the challenges elsewhere. Tropical insects are understudied, not unimportant.</p><img src="https://counter.theconversation.com/content/162626/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Liam N. Nash receives funding from the Natural Environment Research Council, UK.</span></em></p>New data from tropical and subtropical regions suggests insects are declining thanks to dammed riversLiam N. Nash, Ecology PhD researcher, Queen Mary University of LondonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1588382021-04-26T14:54:39Z2021-04-26T14:54:39ZMammals face an uncertain future as global temperatures rise<figure><img src="https://images.theconversation.com/files/396786/original/file-20210423-13-1vtqfyc.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C4096%2C2722&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Meerkats on high alert.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/ronmacphotos/9687131881">Ronnie MacDonald/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>Even with fires, droughts and floods regularly in the news, it’s difficult to comprehend the human toll of the climate crisis. It’s harder still to understand what a warming world will mean for all the other species we share it with. This is true for even our closest relatives in the animal kingdom – the mammals. From mice to elephants, mammals are being affected by rising global temperatures in positive and negative ways that are hard to keep track of.</p>
<p>Take Svalbard reindeer. In their wintry habitats, rain falling on snow creates impenetrable ice sheets that envelop the vegetation that the reindeer eat. Conditions like these are only set to become more common in the changing climate. </p>
<p>You’d expect this to spell trouble for the species, but a <a href="https://doi.org/10.1038/s41467-019-09332-5">recent study</a> showed that climate change might actually stabilise reindeer populations. Why? Because more rain on snow is likely to cull young or elderly reindeer, easing competition within a reduced population to the benefit of more resilient age groups.</p>
<figure class="align-center ">
<img alt="A reindeer noses the grass on an Arctic plain in summer." src="https://images.theconversation.com/files/397064/original/file-20210426-23-wpznj9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/397064/original/file-20210426-23-wpznj9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/397064/original/file-20210426-23-wpznj9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/397064/original/file-20210426-23-wpznj9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/397064/original/file-20210426-23-wpznj9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/397064/original/file-20210426-23-wpznj9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/397064/original/file-20210426-23-wpznj9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Reindeer may be more resilient to climate change than first impressions suggest.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/landscape-wild-reindeer-summer-svalbard-massive-1165210903">Ginger_polina_bublik/Shutterstock</a></span>
</figcaption>
</figure>
<p>Let’s consider another case: the meerkat. This African dryland specialist is adapted to withstand severe seasonal droughts, so hotter seasons shouldn’t really be an issue. But timing is important. When warmer weather combines with <a href="https://doi.org/10.1126/science.aau5905">more unpredictable rainfall</a> just before breeding season begins, it can reduce fertility and raise the risk of extinction for some meerkat populations.</p>
<p>We know that the effects of climate change are complex. Yet, in new research supported by <a href="https://www.idiv.de/en/index.html">the iDiv</a>, the German Center for Biodiversity, our international group of researchers set out to assess whether biodiversity studies – particularly those in regions experiencing the biggest changes in weather – actually examined the impacts of climate change on mammal populations. As it turns out, many of them didn’t.</p>
<h2>Understanding climate change with mammals</h2>
<p><a href="https://doi.org/10.1111/1365-2656.13467">Our study</a> found that climate affects mammal populations in both positive and negative ways, depending on the lifecycle stage of an animal – whether a cub, juvenile, or adult – or their interactions with other species around them. </p>
<p>In the case of impala – a species <a href="https://dx.doi.org/10.2305/IUCN.UK.2016-2.RLTS.T550A50180828.en">particularly vulnerable</a> to increasing drought – less rainfall doesn’t necessarily harm their chances of survival or reproduction. Like the Svalbard reindeer, the effects of climate change tend to only bite when populations are especially dense. </p>
<p>Understanding these complex interactions is deeply important. Impala and reindeer, like many mammals, are not just a food source for humans: their eating habits also control plant populations, which in turn provide clean water, healthy soil and nourishment for other species in the food web. It’s in our interest to understand how mammals react to climate change, to learn how we – and the wider environment – might fare.</p>
<p>There’s a lot of work to be done. So far, researchers have only assessed the climate’s often contradictory effects on <a href="https://doi.org/10.1111/1365-2656.13467">87 mammal species</a> – about 1% of the known 6,400 mammal species worldwide. Worse, we know very little about these complex potential effects in parts of the world most likely to see the biggest changes in temperature and precipitation, such as the Arctic.</p>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/how-animals-are-coping-with-the-global-weirding-of-the-earths-seasons-140856">How animals are coping with the global 'weirding' of the Earth's seasons</a>
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<h2>Unlocking survival secrets</h2>
<p>Human influences on the environment also tend to make the changing climate’s effects worse. In regions with lots of species, like the tropics, the destruction of habitat by people has combined with <a href="https://doi.org/10.1146/annurev-ecolsys-110218-025005">more unpredictable weather</a> to cause particular harm to mammals. </p>
<p>Lemurs in Madagascar, already threatened by deforestation, are now facing drier weather – adding food scarcity to an already long list of threats. But without data tracking how species are responding at different stages of their lives in these regions, it’s difficult to predict what might happen next. </p>
<p>To effectively predict the fate of mammals, scientists need data collected from studying individual animals at many sites and across many years. This can tell us about their chances of survival and reproduction. </p>
<p>More than four decades tracking one North American mammal, the yellow-bellied marmot, has given scientists an incredibly detailed understanding of how species may actually adapt to climate change. As growing seasons have lengthened, there are more alpine plants for marmots to eat throughout the year. These ground squirrels have responded by staying active for longer and gorging, <a href="https://doi.org/10.1038/nature09210">steadily increasing their body mass</a> as a result. Following individual animals across thousands of acres and decades can unveil how our closest relatives are learning to adapt to a changing world. </p>
<figure class="align-center ">
<img alt="A small furry mammal sitting on a rock in a snowy landscape." src="https://images.theconversation.com/files/394548/original/file-20210412-17-h4kirw.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/394548/original/file-20210412-17-h4kirw.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/394548/original/file-20210412-17-h4kirw.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/394548/original/file-20210412-17-h4kirw.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/394548/original/file-20210412-17-h4kirw.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/394548/original/file-20210412-17-h4kirw.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/394548/original/file-20210412-17-h4kirw.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A one-year-old yellow-bellied marmot.</span>
<span class="attribution"><span class="source">Dr Arpat Ozgul</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Out of all the types of animal on the planet, the furry and cuddly charms of mammals win them <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5730207/?">disproportionate scientific attention</a>. If our climate-related data on mammals is nonetheless this scarce, then our lack of knowledge on how climate change affects other, less charismatic groups of species, like insects or amphibians – who are highly vulnerable to <a href="https://doi.org/10.1098/rsbl.2016.0236">climate-driven extinction</a> – should sound alarm bells.</p><img src="https://counter.theconversation.com/content/158838/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Rob Salguero-Gómez receives funding from UKRI.</span></em></p><p class="fine-print"><em><span>Maria Paniw does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Tracking species over their lifetimes can reveal their climate adaptation secrets.Maria Paniw, Research Fellow in Conservation Biology and Global Change, Estación Biológica de Doñana (EBD-CSIC)Rob Salguero-Gómez, Associate Professor of Ecology, University of OxfordLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1584242021-04-08T03:33:56Z2021-04-08T03:33:56ZMarine life is fleeing the equator to cooler waters. History tells us this could trigger a mass extinction event<figure><img src="https://images.theconversation.com/files/393911/original/file-20210408-15-m3sn1z.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C3365%2C2358&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>The tropical water at the equator is renowned for having the richest diversity of marine life on Earth, with vibrant coral reefs and large aggregations of tunas, sea turtles, manta rays and whale sharks. The number of marine species naturally tapers off as you head towards the poles. </p>
<p>Ecologists have assumed this global pattern has remained stable over recent centuries — until now. <a href="https://www.pnas.org/content/118/15/e2015094118">Our recent study</a> found the ocean around the equator has already become too hot for many species to survive, and that global warming is responsible. </p>
<p>In other words, the global pattern is rapidly changing. And as species flee to cooler water towards the poles, it’s likely to have profound implications for marine ecosystems and human livelihoods. When the same thing happened 252 million years ago, 90% of all marine species died.</p>
<h2>The bell curve is warping dangerously</h2>
<p>This global pattern — where the number of species starts lower at the poles and peaks at the equator — results in a bell-shaped gradient of species richness. We looked at distribution records for nearly 50,000 marine species collected since 1955 and found a growing dip over time in this bell shape. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/393752/original/file-20210407-19-cqd2db.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A chart with three overlapping lines, each representing different decades. It shows that between 1955 and 1974, the bell curve is almost flat at the top. For the lines 1975-1994 and 1995-2015, the dip gets progressively deeper, with peaks either side of the centre." src="https://images.theconversation.com/files/393752/original/file-20210407-19-cqd2db.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/393752/original/file-20210407-19-cqd2db.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/393752/original/file-20210407-19-cqd2db.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/393752/original/file-20210407-19-cqd2db.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/393752/original/file-20210407-19-cqd2db.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/393752/original/file-20210407-19-cqd2db.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/393752/original/file-20210407-19-cqd2db.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">If you look at each line in this chart, you can see a slight dip in total species richness between 1955 and 1974. This deepens substantially in the following decades.</span>
<span class="attribution"><span class="source">Anthony Richardson</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>So, as our oceans warm, species have tracked their preferred temperatures by moving towards the poles. Although the warming at the equator of 0.6°C over the past 50 years is relatively modest compared with warming at higher latitudes, <a href="https://science.sciencemag.org/content/334/6056/652">tropical species have to move further</a> to remain in their thermal niche compared with species elsewhere. </p>
<p>As ocean warming has accelerated over recent decades due to climate change, the dip around at the equator has deepened. </p>
<p><a href="https://www.nature.com/articles/nclimate2769">We predicted</a> such a change five years ago using a modelling approach, and now we have observational evidence.</p>
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<p>
<em>
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Read more:
<a href="https://theconversation.com/the-ocean-is-becoming-more-stable-heres-why-that-might-not-be-a-good-thing-157911">The ocean is becoming more stable – here's why that might not be a good thing</a>
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<p>For each of the 10 major groups of species we studied (including pelagic fish, reef fish and molluscs) that live in the water or on the seafloor, their richness either plateaued or declined slightly at latitudes with mean annual sea-surface temperatures above 20°C. </p>
<p>Today, species richness is greatest in the northern hemisphere in latitudes around 30°N (off southern China and Mexico) and in the south around 20°S (off northern Australia and southern Brazil).</p>
<figure class="align-center ">
<img alt="school of tuna fish" src="https://images.theconversation.com/files/393937/original/file-20210408-13-1cvlkq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/393937/original/file-20210408-13-1cvlkq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/393937/original/file-20210408-13-1cvlkq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/393937/original/file-20210408-13-1cvlkq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/393937/original/file-20210408-13-1cvlkq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/393937/original/file-20210408-13-1cvlkq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/393937/original/file-20210408-13-1cvlkq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The tropical water at the equator is renowned for having the richest diversity of marine life, including large aggregations of tuna fish.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
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</figure>
<h2>This has happened before</h2>
<p>We shouldn’t be surprised global biodiversity has responded so rapidly to global warming. This has happened before, and with dramatic consequences. </p>
<p><strong>252 million years ago…</strong></p>
<p>At the end of the Permian geological period about 252 million years ago, global temperatures warmed by 10°C over 30,000-60,000 years as a result of greenhouse gas emissions from volcano eruptions in Siberia. </p>
<p><a href="https://www.pnas.org/content/117/30/17578">A 2020 study</a> of the fossils from that time shows the pronounced peak in biodiversity at the equator flattened and spread. During this mammoth rearranging of global biodiversity, 90% of all marine species were killed. </p>
<p><strong>125,000 years ago…</strong></p>
<p><a href="https://www.pnas.org/content/109/52/21378">A 2012 study showed</a> that more recently, during the rapid warming around 125,000 years ago, there was a similar swift movement of reef corals away from the tropics, as documented in the fossil record. The result was a pattern similar to the one we describe, although there was no associated mass extinction. </p>
<p>Authors of the study suggested their results might foreshadow the effects of our current global warming, ominously warning there could be mass extinctions in the near future as species move into the subtropics, where they might struggle to compete and adapt. </p>
<p><strong>Today…</strong></p>
<p><a href="https://www.pnas.org/content/117/23/12891">During the last ice age</a>, which ended around 15,000 years ago, the richness of forams (a type of hard-shelled, single-celled plankton) peaked at the equator and has been dropping there ever since. This is significant as plankton is a keystone species in the foodweb.</p>
<p>Our study shows that decline has accelerated in recent decades due to human-driven climate change.</p>
<h2>The profound implications</h2>
<p>Losing species in tropical ecosystems means ecological resilience to environmental changes is reduced, potentially compromising ecosystem persistence. </p>
<p>In subtropical ecosystems, species richness is increasing. This means there’ll be species invaders, novel predator-prey interactions, and new competitive relationships. For example, <a href="https://www.abc.net.au/news/2019-09-13/sydney-growing-own-coral-reef-with-help-from-tropical-fish/11466192">tropical fish</a> moving into Sydney Harbour compete with temperate species for food and habitat.</p>
<p>This could result in ecosystem collapse — as was seen at the boundary between the Permian and Triassic periods — in which species go extinct and ecosystem services (such as food supplies) are permanently altered. </p>
<p>The changes we describe will also have profound implications for human livelihoods. For example, many tropical island nations depend on the revenue from tuna fishing fleets through the selling of licenses in their territorial waters. Highly mobile tuna species are likely to move rapidly toward the subtropics, potentially beyond sovereign waters of island nations. </p>
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Read more:
<a href="https://theconversation.com/tropical-fisheries-does-limiting-international-trade-protect-local-people-and-marine-life-133403">Tropical fisheries: does limiting international trade protect local people and marine life?</a>
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<p>Similarly, many reef species important for artisanal fishers — and highly mobile megafauna such as whale sharks, manta rays and sea turtles that support tourism — are also likely to move toward the subtropics. </p>
<p>The movement of commercial and artisanal fish and marine megafauna could compromise the ability of tropical nations to meet the <a href="https://sdgs.un.org/goals">Sustainable Development Goals</a> concerning zero hunger and marine life. </p>
<h2>Is there anything we can do?</h2>
<p>One pathway is laid out in the Paris Climate Accords and involves aggressively reducing our emissions. Other opportunities are also emerging that could help safeguard biodiversity and hopefully minimise the worst impacts of it shifting away from the equator.</p>
<p>Currently 2.7% of the ocean is conserved in <a href="https://mpatlas.org">fully or highly protected reserves</a>. This is well short of the 10% target by 2020 under the UN Convention on Biological Diversity. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/393915/original/file-20210408-19-46u3s8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Manta ray with other fish" src="https://images.theconversation.com/files/393915/original/file-20210408-19-46u3s8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/393915/original/file-20210408-19-46u3s8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/393915/original/file-20210408-19-46u3s8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/393915/original/file-20210408-19-46u3s8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/393915/original/file-20210408-19-46u3s8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/393915/original/file-20210408-19-46u3s8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/393915/original/file-20210408-19-46u3s8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Manta rays and other marine megafauna leaving the equator will have a huge impact on tourism.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
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<p>But <a href="https://www.gov.uk/government/topical-events/global-ocean-alliance-30by30-initiative/about#global-ocean-alliance-members">a group of 41 nations</a> is pushing to set a new target of protecting 30% of the ocean by 2030. </p>
<p>This “30 by 30” target could ban seafloor mining and remove fishing in reserves that can destroy habitats and release as much carbon dioxide as <a href="https://www.nature.com/articles/s41586-021-03371-z">global aviation</a>. These measures would remove pressures on biodiversity and promote ecological resilience. </p>
<p>Designing climate-smart reserves could further protect biodiversity from future changes. For example, reserves for marine life could be placed in refugia where the climate will be stable over the foreseeable future. </p>
<p>We now have evidence that climate change is impacting the best-known and strongest global pattern in ecology. We should not delay actions to try to mitigate this.</p>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/369797/original/file-20201117-13-180ibt9.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/369797/original/file-20201117-13-180ibt9.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/369797/original/file-20201117-13-180ibt9.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/369797/original/file-20201117-13-180ibt9.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/369797/original/file-20201117-13-180ibt9.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=504&fit=crop&dpr=1 754w, https://images.theconversation.com/files/369797/original/file-20201117-13-180ibt9.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=504&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/369797/original/file-20201117-13-180ibt9.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=504&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p><strong><em>This story is part of <a href="https://theconversation.com/uk/topics/oceans-21-96784">Oceans 21</a></em></strong>
<br><em>Our series on the global ocean opened with <a href="https://oceans21.netlify.app/">five in-depth profiles</a>. Look out for new articles on the state of our oceans in the lead-up to the UN’s next climate conference, COP26. The series is brought to you by The Conversation’s international network.</em></p>
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Read more:
<a href="https://theconversation.com/australias-marine-un-protected-areas-government-zoning-bias-has-left-marine-life-in-peril-since-2012-153795">Australia's marine (un)protected areas: government zoning bias has left marine life in peril since 2012</a>
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<img src="https://counter.theconversation.com/content/158424/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Anthony Richardson receives funding from the Australian Research Council.</span></em></p><p class="fine-print"><em><span>Chhaya Chaudhary works for Goethe University, Frankfurt am Main, Germany. During her PhD studies (2014- 2019), she received part- funding from the European Marine Observation Data Network (EMODnet) Biology project funded by the European Commission’s Directorate—General for Maritime Affairs and Fisheries (DG MARE), and received U21 Doctoral Mobility Scholarship from the University of Auckland in 2016. </span></em></p><p class="fine-print"><em><span>David Schoeman receives funding from the Australian Research Council. </span></em></p><p class="fine-print"><em><span>Mark John Costello does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Climate change has already made tropical oceans too hot for some marine species to survive. As they flee towards the poles, the implications for ecosystems and human livelihoods will be profound.Anthony Richardson, Professor, The University of QueenslandChhaya Chaudhary, University of Auckland, Waipapa Taumata RauDavid Schoeman, Professor of Global-Change Ecology, University of the Sunshine CoastMark John Costello, Professor, University of Auckland, Waipapa Taumata RauLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1581052021-04-01T18:47:35Z2021-04-01T18:47:35Z‘Godzilla vs. Kong’: Monster movies evoke adventure but also ‘dangers’ of tropics<figure><img src="https://images.theconversation.com/files/393182/original/file-20210401-19-kx3hwy.jpeg?ixlib=rb-1.1.0&rect=16%2C12%2C1349%2C679&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Hollywood movies have historically represented the tropics as lush green coasts but lurking underneath is disease and danger.</span> <span class="attribution"><span class="source">(Warner Bros.)</span></span></figcaption></figure><p>For audiences stuck in their living rooms, the new monster film <em>Godzilla vs. Kong</em> offers an opportunity to do some armchair travelling. But before you imagine a tropical island getaway — perhaps a lounge-chair by a beach soaked in sunshine — this is a monster movie and so you must also make room for a scary lurking creature. </p>
<p>The duality of these images are with us partly because <a href="https://www.ubcpress.ca/hollywoods-hawaii">Hollywood movies have long leaned into colonial representations</a> of the tropics: imagined as romantic palm-fringed coasts full of abundance and natural fertility, but also scary places full of <a href="https://doi.org/10.1111/1467-9493.00060">pestilence, disease and primitiveness</a> and previously “undiscovered” creatures. </p>
<p>Through stories of colonial exploration, tropical landscapes become places where the western explorer can experience the unbridled sensuality of nature as well as the thrill of danger from the unknown. In this view, the tropics become a landscape where nature towers over man, a power imbalance that monster films seek to address. </p>
<p>Though these films start with tropical locales, the threat posed by mega-creatures does not become real until they cross into the realms of the western world. For example, Godzilla’s journey begins with former colonies and ends in New York. </p>
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<a href="https://images.theconversation.com/files/393148/original/file-20210401-15-dk362f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Book Cover: Contagious: Cultures, Carriers and the Outbreak Narrative" src="https://images.theconversation.com/files/393148/original/file-20210401-15-dk362f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/393148/original/file-20210401-15-dk362f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=882&fit=crop&dpr=1 600w, https://images.theconversation.com/files/393148/original/file-20210401-15-dk362f.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=882&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/393148/original/file-20210401-15-dk362f.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=882&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/393148/original/file-20210401-15-dk362f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1108&fit=crop&dpr=1 754w, https://images.theconversation.com/files/393148/original/file-20210401-15-dk362f.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1108&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/393148/original/file-20210401-15-dk362f.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1108&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Monster movies are about protecting western lands and people from exposure to strange lands, people and disease.</span>
<span class="attribution"><span class="source">(Duke Press)</span></span>
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<p>The problem in these monster movies then becomes one of protecting western lands and people from <a href="https://www.dukeupress.edu/bioinsecurities">exposure to strange lands</a> and the “aberrant” creatures and people contained in those lands. Non-western landscapes and people thus become endowed with the burden of embodying these threats, magnified many times over in monster films. The same trajectory is also invoked with narratives of disease transmission: <a href="https://doi.org/10.1215/9780822390572">from a “primitive” space to the metropolitan centre</a>. </p>
<p>Although <a href="https://www.hakaimagazine.com/news/godzillas-island-origin/">Godzilla originated out of Japanese history and culture</a>, when it crossed over into Hollywood, the setting of the films relied on tropes from colonial history. So while monster films may be entertaining, they build on structures with long imperial histories and have implications for the way <a href="http://www.siupress.com/books/978-0-8093-2624-2">Hollywood audiences perceive the tropics</a>.</p>
<h2>‘Savage wilderness’</h2>
<p>The narratives of tropics simultaneously containing possibilities for paradise and pestilence can be traced back to the beginning of colonial scientific exploration.</p>
<p>These ideas come alive in <a href="https://search.proquest.com/openview/61933b5a4492e779/1?pq-origsite=gscholar&cbl=2599">a 19th-century explorer’s account of a journey </a> to French Guiana. He writes about “virgin forests,” “tropical luxuriance,” “wild denizens” and their “gloomy recesses” and “the poetry of savage wilderness.”</p>
<p>The 19th-century British explorer, Joseph Banks, who accompanied cartographer James Cook on his voyage to the South Pacific, marvelled <a href="https://www.sl.nsw.gov.au/joseph-banks-endeavour-journal">how nature had provided for the inhabitants of these lands in abundance. He even said the tropical land yielded fruit without labour</a>. These perceptions shaped the idea of tropics as a place of natural abundance, and gave rise to the trope of <a href="https://www.upenn.edu/pennpress/book/14096.html">tropical bounty</a>. </p>
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Read more:
<a href="https://theconversation.com/earth-day-colonialisms-role-in-the-overexploitation-of-natural-resources-113995">Earth Day: Colonialism's role in the overexploitation of natural resources</a>
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<p>The “discovery” of new lands was combined with the impulse to <a href="https://www.cambridge.org/ca/academic/subjects/history/regional-history-after-1500/green-imperialism-colonial-expansion-tropical-island-edens-and-origins-environmentalism-16001860">recreate the Biblical idea of an Eden, or paradise on Earth</a>, a phenomenon which played out with colonial explorers on tropical islands. </p>
<h2>The yellow filter</h2>
<p>Hollywood’s monster films like <em>Godzilla</em> (1998, 2014) and <em>Kong: Skull Island</em> (2017) have used similar ideas. In all three films, the tropical island is an important setting, a place where the story is set in motion. All three films fall into similar patterns and use similar techniques to depict the tropics versus the west.</p>
<p>The opening sequences in the 1998 and 2014 versions of <em>Godzilla</em> rely on footage of sepia-toned palm lined beaches, Indigenous Peoples and a warmly lit mine next to a lush forest in the Philippines. </p>
<p>The sepia tone in the 1998 <em>Godzilla</em> resembles Hollywood’s common use of the <a href="https://matadornetwork.com/read/yellow-filter-american-movies/">yellow filter</a> to show tropical locations. Critics like journalist Elisabeth Sherman have pointed out the use of the yellow filter as something western movie makers do to “depict warm, tropical, dry climates.” But she says, “it makes the landscape in question look jaundiced and unhealthy.” <em>Kong: Skull Island</em> also makes use of a warm yellow tinge for the scenes that unfold in the tropical jungle that is Kong’s turf.</p>
<h2>The photographic lens</h2>
<p>Modes of representation such as the camera and photography were <a href="https://www.nytimes.com/2019/02/06/magazine/when-the-camera-was-a-weapon-of-imperialism-and-when-it-still-is.html">part of the imperial apparatus</a>. As technology brought by the white explorers, photography provided a means to <a href="https://press.uchicago.edu/ucp/books/book/distributed/P/bo15581095.html">capture the land, erase and arrange the people</a> being looked at through the camera.</p>
<figure class="align-center ">
<img alt="Two people, one with a gun raised and one with a camera search under dinosaur bones." src="https://images.theconversation.com/files/393154/original/file-20210401-15-107io6u.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/393154/original/file-20210401-15-107io6u.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/393154/original/file-20210401-15-107io6u.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/393154/original/file-20210401-15-107io6u.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/393154/original/file-20210401-15-107io6u.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/393154/original/file-20210401-15-107io6u.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/393154/original/file-20210401-15-107io6u.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">A scene from ‘Kong: Skull Island.’ Brie Larson plays the photographer and Tom Hiddleston is the tracker.</span>
<span class="attribution"><span class="source">(Warner Bros.)</span></span>
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<p><em>Kong: Skull Island</em> features an “uncharted” island in the South Pacific. In the film, the inhabitants of the island are often shown through the photographer’s camera. The residents are mute in the film; the audience and the rest of the team in Skull Island need the westerner’s help to parse what they mean with their gestures.</p>
<h2>Depicting Indigenous Peoples as in the past</h2>
<p>In <em>Kong: Skull Island</em>, expedition leader William Randa (played by John Goodman) tries to get funding for his trip to the uncharted island by describing it as a place “where God did not finish creation” or, in other words, a place where time has stood still. </p>
<p>Indeed, the inhabitants of Skull Island are situated squarely in a <a href="http://cup.columbia.edu/book/time-and-the-other/9780231169264">prehistoric</a> time-frame, separate from the contemporary time inhabited by the explorers.</p>
<p>Building on the colonial imagination that casts Indigenous inhabitants as being close to nature, the 2021 film features an Indigenous girl from Skull Island as the sole contact between Kong and the rest of the world. </p>
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<figcaption><span class="caption">Official trailer of King Kong vs. Godzilla/Warner Bros. 2021.</span></figcaption>
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<p>With its unknown creatures and lush forests, Skull Island occupies a different space-time. These sentiments of the Indigenous populations and flora and fauna were commonly expressed by colonial explorers. Ernst Haeckel, the famous naturalist and proponent of Darwinism, on his visit to Sri Lanka said the flora of the land reminded him of <a href="https://archive.org/details/visittoceylon00haecuoft">fossils from earlier geological ages</a>. </p>
<p>Reminiscent of the competition between various colonial powers to map “unknown” lands and resources, what gets Randa his funding is the assurance that Americans will “discover” the uncharted island first.</p>
<h2>Old texts still have everyday impact</h2>
<p><em>Kong: Skull Island</em> builds on the long history of colonial literature. Two characters in the film: the tracker, named Conrad (played by Tom Hiddleston), and Marlow (John C. Reilly) are a nod to the literary journey up the Congo river in the novel, <em><a href="https://www.penguinrandomhouse.com/books/310601/heart-of-darkness-by-joseph-conrad/">Heart of Darkness</a></em> about an explorer named Marlow and written by Joseph Conrad. The novel’s premise that the journey up the Congo river is a journey into darkness <a href="https://www.massreview.org/volume-57-issue-1">has raised many debates</a> about the racism in Conrad’s text. </p>
<p>Though the new <em>Godzilla vs. Kong</em> offers the two mega-creatures a common enemy, the film still traffics in established tropes of monster films. </p>
<p>For decades, these landscapes have been characterized as sites of abundance but also disease outbreaks. At the same time, they also become places full of resources that need extraction. In Hollywood and colonial literature imaginations, the tropics hold cures for disease, alternative medicines and other geological resources, building on the long history of collaboration between <a href="https://www.smithsonianmag.com/science-nature/science-bears-fingerprints-colonialism-180968709/">scientists and the colonial enterprise</a>. </p>
<p>Even though these tropes came into being centuries ago as a result of colonial expeditions, they still underpin how space gets imagined in contemporary pop culture, revealing the everyday impact of old literary texts.</p><img src="https://counter.theconversation.com/content/158105/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Priscilla Jolly does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Hollywood movies have long leaned into colonial representations of the tropics: imagined as romantic palm-fringed coasts full of abundance, but also scary places full of pestilence and primitiveness.Priscilla Jolly, PhD student, Department of English, Concordia UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1451742020-09-15T19:52:08Z2020-09-15T19:52:08ZClimate explained: will the tropics eventually become uninhabitable?<figure><img src="https://images.theconversation.com/files/357408/original/file-20200910-23-3l00q5.jpg?ixlib=rb-1.1.0&rect=36%2C100%2C2993%2C1918&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/shenghunglin/1360133699/">Flickr/</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span></figcaption></figure><figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/287622/original/file-20190811-144878-bvgm9l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/287622/original/file-20190811-144878-bvgm9l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/287622/original/file-20190811-144878-bvgm9l.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/287622/original/file-20190811-144878-bvgm9l.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/287622/original/file-20190811-144878-bvgm9l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/287622/original/file-20190811-144878-bvgm9l.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/287622/original/file-20190811-144878-bvgm9l.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p><strong>What is the impact of temperature increases in the tropics? How likely is it that regions along the Equator will be uninhabitable due to high wet bulb temperatures such as 35°C and more in places like Singapore? Do we have models that suggest how likely this is and at what time frames?</strong></p>
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<p>More than <a href="https://www.jcu.edu.au/state-of-the-tropics">3.3 billion people</a> live in the tropics, representing about 40% of the world’s population. Despite some areas of affluence, such as Singapore, the tropics are also home to about <a href="https://www.jcu.edu.au/state-of-the-tropics/publications/2020">85% of the world’s poorest people</a> and are therefore particularly susceptible to the impacts of climate change.</p>
<p>The tropics are expected to experience rising temperatures and changes to rainfall, and the question is whether this could make this region uninhabitable. How would this happen?</p>
<h2>Heat stress</h2>
<p>Humans regulate their body temperature in warm conditions through sweating. The sweat evaporates and cools the skin. But if conditions are humid, sweating and evaporation are much less effective.</p>
<p>Humans can survive and function in quite high temperatures if humidity is low, but as humidity increases our ability to function decreases rapidly. This effect is measured by a <a href="https://www.weather.gov/safety/heat-index">heat stress index</a> which shows the apparent temperature you feel under different relative humidity conditions.</p>
<p>From a human health point of view, the wet bulb temperature is critical. This is the temperature a thermometer covered in a wet cloth would measure, and it reflects the maximum amount of cooling that can be achieved by evaporation. </p>
<p>High wet bulb temperatures are <a href="https://www.nature.com/articles/nclimate1827" title="Reductions in labour capacity from heat stress under climate warming">more problematic to human health</a> than high absolute temperatures. Wet bulb temperatures above 35°C are life-threatening because they cause <a href="https://www.nih.gov/news-events/news-releases/hyperthermia-too-hot-your-health-1">hyperthermia</a>, which means the body cannot cool down and the internal body temperature exceeds 40°C. </p>
<p>Climate modelling predictions used by the Intergovernmental Panel on Climate Change (<a href="https://www.ipcc.ch/">IPCC</a>) for the period from 2080-2100 suggest <a href="https://www.ipcc.ch/site/assets/uploads/2018/02/WG1AR5_Chapter12_FINAL.pdf">warming in the tropics</a> of about 1.6°C under mid-range emissions scenarios and up to 3.3°C under high emissions scenarios, with error margins of about 0.5°C on both predictions.</p>
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Read more:
<a href="https://theconversation.com/siberia-heatwave-why-the-arctic-is-warming-so-much-faster-than-the-rest-of-the-world-141455">Siberia heatwave: why the Arctic is warming so much faster than the rest of the world</a>
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<p>Different parts of the world respond in different ways to warming from greenhouse gas emissions. The projected warming in the tropics represents about 40% of the expected temperature rise in the Arctic. </p>
<p>High-latitude regions – far north or south of the Equator – warm more rapidly than the global average because excess heat in the tropics creates a temperature and pressure gradient. This drives heat up to higher elevations and higher latitudes through an atmospheric circulation called the <a href="https://www.britannica.com/science/Hadley-cell">Hadley cell</a>. </p>
<p>The stronger the gradient, the more heat is exported. </p>
<h2>Hot in the city</h2>
<p>There is one additional factor: urbanisation. Singapore is a good place to look at actual climate change in the tropics.</p>
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<a href="https://images.theconversation.com/files/357411/original/file-20200910-23-ntad7x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A Singapore skyline with clouds and some sun breaking through." src="https://images.theconversation.com/files/357411/original/file-20200910-23-ntad7x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/357411/original/file-20200910-23-ntad7x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/357411/original/file-20200910-23-ntad7x.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/357411/original/file-20200910-23-ntad7x.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/357411/original/file-20200910-23-ntad7x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/357411/original/file-20200910-23-ntad7x.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/357411/original/file-20200910-23-ntad7x.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Cities such as Singapore will get hotter.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/mohammadhasan/8682523143/">Flickr/Mohammad Hasan</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span>
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<p><a href="https://www.nccs.gov.sg/singapores-climate-action/impact-of-climate-change-in-Singapore/">Records</a> from Singapore indicate temperatures have increased by 1.1°C over 42 years to 2014. This is nearly <a href="https://www.todayonline.com/singapore/singapore-growing-warmer-twice-global-average">twice the average global rate</a> of warming over <a href="https://www.climatechangeinaustralia.gov.au/en/climate-projections/future-climate/global-climate-change/causes-past-and-recent-change/">recent decades</a> and is opposite to expectations.</p>
<p>The difference appears to be due to a <a href="https://www.epa.gov/heatislands/learn-about-heat-islands">heat island</a> effect caused by the city itself. This is important because changes in land use amplify background global climate change and put tropical cities at greater risk of extreme heat. As populations are concentrated in cities, this increases the risk to human health.</p>
<p>The mean average temperature for <a href="http://www.weather.gov.sg/climate-climate-of-singapore/">Singapore is about 27°C</a>, whereas Jakarta in Indonesia is slightly warmer. At the scale of predicted mean annual temperature change, neither of these cities would become uninhabitable. But even a small temperature increase would make life more challenging.</p>
<p>This is made worse in at least some parts of the tropics, because total <a href="https://www.nasa.gov/press/2015/goddard/march/increased-rainfall-in-tropics-caused-by-more-frequent-big-storms-0">rainfall is increasing</a>, suggesting a long-term rise in humidity. For example, <a href="https://www.nccs.gov.sg/singapores-climate-action/impact-of-climate-change-in-singapore/">average rainfall</a> in Singapore increased by more than 500mm from 2,192mm in 1980 to 2,727mm in 2014. </p>
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<strong>
Read more:
<a href="https://theconversation.com/urban-growth-heat-islands-humidity-climate-change-the-costs-multiply-in-tropical-cities-120825">Urban growth, heat islands, humidity, climate change: the costs multiply in tropical cities</a>
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<h2>Deadly heat</h2>
<p>People working outdoors are at higher risk, as are vulnerable populations, including the elderly. Under the IPCC’s high-emission trajectory, heat-related deaths in Jakarta in August are <a href="https://www.nature.com/articles/s41598-020-66288-z" title="Future increase in elderly heat-related mortality of a rapidly growing Asian megacity">expected to rise</a> from about 1,800 in 2010 to nearly 27,000 in 2050.</p>
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<a href="https://images.theconversation.com/files/357416/original/file-20200910-18-1imgxh3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="People unloading cargo in the outdoors at Jakarta port." src="https://images.theconversation.com/files/357416/original/file-20200910-18-1imgxh3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/357416/original/file-20200910-18-1imgxh3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/357416/original/file-20200910-18-1imgxh3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/357416/original/file-20200910-18-1imgxh3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/357416/original/file-20200910-18-1imgxh3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/357416/original/file-20200910-18-1imgxh3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/357416/original/file-20200910-18-1imgxh3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Working outdoors in the increased heat and humidity will get harder.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/jorienlondon/2935974720/">Flickr/Jorien</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span>
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<p>Even allowing for a significant increase in elderly people as the Indonesian population ages, this means about 15,000 excess deaths in this month. Estimates under high-emission predictions for the tropics and mid-latitudes suggest about a <a href="https://www.nature.com/articles/nclimate1827" title="Reductions in labour capacity from heat stress under climate warming">40% decline in the ability to undertake manual work</a> during the warmest month by 2050.</p>
<p>These impacts will be stronger in the seasonally wet tropics (such as the Northern Territory of Australia), where more extreme warming is expected than in the equatorial zone.</p>
<p>Predictions for Darwin, in northern Australia, suggest an <a href="https://www.climatechangeinaustralia.gov.au/media/ccia/2.1.6/cms_page_media/176/CCIA_Australian_cities_1.pdf">increase in days with temperatures above 35°C</a> from 11 days a year in 2015 to an average of 43 days under the mid-range emission scenario (IPCC’s <a href="https://link.springer.com/article/10.1007/s10584-011-0151-4">RCP4.5</a> scenario) by 2030 and an average of 111 (range 54-211) days by 2090. Under the higher emission scenario (IPCC’s <a href="https://www.carbonbrief.org/explainer-the-high-emissions-rcp8-5-global-warming-scenario">RCP8.5</a>), an average of 265 days above 35°C could be reached by 2090. </p>
<p>In summary, while absolute temperatures are expected to rise more slowly in the tropics when compared with higher latitudes and polar regions, the combination of heat and rising humidity will make life challenging, but not impossible.</p><img src="https://counter.theconversation.com/content/145174/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>James Shulmeister receives funding from the Australian Research Council. He has been supported through NSF grants (US), Chinese NSF and Marsden Funding (New Zealand) and other sources.</span></em></p>Absolute temperatures are expected to rise more slowly in the tropics than in higher latitudes and polar regions, but the combination of heat and rising humidity will make life more challenging.James Shulmeister, Professor, School of Earth and Environmental Sciences, University of CanterburyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1274222020-01-17T13:55:16Z2020-01-17T13:55:16ZIdentifying aquatic plants with drones could be the key to reducing a parasitic infection in people<figure><img src="https://images.theconversation.com/files/308128/original/file-20191220-11929-1sl0j2o.jpg?ixlib=rb-1.1.0&rect=15%2C9%2C2029%2C1523&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Researchers operate inexpensive drones to 'see' the areas with the highest likelihood of parasites.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/chelsealwood/34251500273/in/album-72157681532310374/">Chelsea L. Wood/University of Washington</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>For the majority of people on Earth, parasites are a fact of life. These organisms live inside the human body, causing debilitating or fatal diseases. Among the parasitic diseases, one of the very worst is <a href="https://www.cdc.gov/parasites/schistosomiasis/index.html">schistosomiasis</a>, caused by worms living in the human circulatory system. The disease can cause bleeding, organ damage, and elevated risk of HIV infection and cancer. For children, infection can stunt growth and impair cognitive development. </p>
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<a href="https://images.theconversation.com/files/307946/original/file-20191219-11900-eyeje2.jpg?ixlib=rb-1.1.0&rect=18%2C36%2C1515%2C2009&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/307946/original/file-20191219-11900-eyeje2.jpg?ixlib=rb-1.1.0&rect=18%2C36%2C1515%2C2009&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/307946/original/file-20191219-11900-eyeje2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/307946/original/file-20191219-11900-eyeje2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/307946/original/file-20191219-11900-eyeje2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/307946/original/file-20191219-11900-eyeje2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/307946/original/file-20191219-11900-eyeje2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/307946/original/file-20191219-11900-eyeje2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Everyday chores can carry a risk of parasitic exposure for Senegalese villagers.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/chelsealwood/35062512055/in/album-72157681532310374/">Chelsea L. Wood/University of Washington</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
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<p>Schistosome worms infect more than <a href="https://www.who.int/news-room/fact-sheets/detail/schistosomiasis">200 million people globally</a>, most of whom live in sub-Saharan Africa. People become infected with this parasite through contact with contaminated freshwater. The worm penetrates their skin as they bathe, perform agricultural work or carry out domestic chores like washing clothes.</p>
<p>There is no vaccine. Since the 1980s, efforts to eliminate schistosomiasis have primarily focused on distributing drugs to infected people. But recently, the <a href="https://www.who.int/">World Health Organization</a> formally recognized that this strategy <a href="https://apps.who.int/iris/handle/10665/78074">isn’t working</a> in many places, because the treatment provides no protection against future infections. People can rapidly become re-infected when they again come into contact with contaminated water.</p>
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<a href="https://images.theconversation.com/files/307934/original/file-20191219-11939-1vfwq9y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/307934/original/file-20191219-11939-1vfwq9y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/307934/original/file-20191219-11939-1vfwq9y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/307934/original/file-20191219-11939-1vfwq9y.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/307934/original/file-20191219-11939-1vfwq9y.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/307934/original/file-20191219-11939-1vfwq9y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/307934/original/file-20191219-11939-1vfwq9y.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/307934/original/file-20191219-11939-1vfwq9y.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Kids in Maka Diama, Senegal.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/chelsealwood/22616952525/in/album-72157660524369226/">Chesea L. Wood/University of Washington</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
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<p>In addition to drug distribution, WHO emphasizes controlling the snails that incubate the parasitic schistosome worms. The idea is that eliminating the snails could eliminate the disease, since the worms wouldn’t be able to live and replicate in freshwater without them. Although public health officials know eradicating these snails can be a way to manage the schistomosiasis parasite, the challenge is to locate hotspots where the snails flourish.</p>
<p><a href="https://chelsealwood.wordpress.com/">My lab</a> uses ecology, the scientific study of the abundance and distribution of organisms, to develop solutions for infectious diseases. <a href="http://www.theupstreamalliance.org">My colleagues and I</a> work to help public health agencies identify where schistosomiasis hotspots are located. Recently, we made a surprise discovery involving aerial images of aquatic vegetation taken by drones, an approach that may help public health officials gain some real traction in reducing schistosomiasis burdens. </p>
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<h2>Interrupting the life cycle of a parasite</h2>
<p>Most of the parasitic <a href="https://www.who.int/neglected_diseases/diseases/en/">tropical diseases</a> that infect humans are caused by worms with complex life cycles. The link between humans and parasites is the environment. The environment, therefore, is key to reducing transmission of schistosomiasis to people. Since 2014, <a href="https://chelsealwood.wordpress.com/research/diversity-and-human-infectious-disease/">my lab</a> and <a href="http://www.theupstreamalliance.org">our collaborators</a> have worked at the site of the world’s largest recorded schistosomiasis epidemic, the <a href="https://www.google.com/maps/place/Lac+de+Guiers/@16.1817404,-16.1451939,10z/data=!3m1!4b1!4m5!3m4!1s0xe95242e2c6da065:0x298337258282a457!8m2!3d16.2247443!4d-15.8407722">Lower Senegal River Basin</a> in Senegal, West Africa. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/307959/original/file-20191219-11904-5tpq4l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/307959/original/file-20191219-11904-5tpq4l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/307959/original/file-20191219-11904-5tpq4l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/307959/original/file-20191219-11904-5tpq4l.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/307959/original/file-20191219-11904-5tpq4l.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/307959/original/file-20191219-11904-5tpq4l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/307959/original/file-20191219-11904-5tpq4l.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/307959/original/file-20191219-11904-5tpq4l.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A team of Senegalese and U.S. researchers inspect vegetation for snails.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/chelsealwood/27406778881/in/album-72157666764605683/">Chelsea L. Wood/University of Washington</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>When our project began, our goal was to map when and where snails occurred at water-access sites used by villagers. Snails cluster, and we reasoned that once we identified the locations of those clusters, a Senegalese public health team could destroy them by physically removing the snails or using chemical <a href="https://www.who.int/schistosomiasis/resources/9789241511995/en/">molluscicides</a>. Limiting the size of the targeted area would lower the cost to control the snail populations by reducing the expense and environmental and health impacts of application. </p>
<p>Unfortunately, snails don’t stay put. <a href="https://doi.org/10.1073/pnas.1903698116">Our research</a> indicated that targeting snail clusters might not be an efficient way to get rid of them. In fact, it was rare for a snail cluster that we found during one field trip to be present when we returned just a few months later. We went back to the drawing board.</p>
<p>Our team had been using drones to get an aerial image of the aquatic habitat at each water-access site. We noticed that snails tended to associate with certain kinds of aquatic vegetation that were visible in our drone imagery. This realization allowed us to make an important discovery: human schistosomiasis infections were more common at sites where this suitable snail habitat was present. </p>
<h2>Surveillance with inexpensive technology</h2>
<p>This finding led our team to two important realizations.</p>
<p>First, public health agencies in Senegal might be able to prioritize their drug distribution strategy with the help of drone imagery. Getting drugs to those who need them most is important, given that most heavily infected villages tend to be poor, extremely remote, and difficult or expensive to access.</p>
<p>Consumer-grade drones are affordable and may reduce the time and effort needed to evaluate the health of people living in remote villages. The aquatic plants in waterways are easy to see from the air. They can provide a visual proxy for where schistosome-carrying snails are located, suggesting that there may be higher human infection rates in that area. That information could lead to better data on the distribution of human infections and, therefore, to more efficient drug allocation. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/BAJm3XYzKUc?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Drone flyover of Mbarigot, a village outside of the city of Saint Louis, Senegal. (Andrew J. Chamberlin, Stanford University)</span></figcaption>
</figure>
<p>Second, while we found that it would be impractical to identify and target snail clusters, it could be efficient to target the vegetation that serves as snail habitat. Molluscicide could be applied to patches of this vegetation to destroy any snails within. Another option would be to physically remove the vegetation. Our team is testing the effectiveness of removing vegetation to reduce snail abundance and human infection burden. </p>
<p>Ecology is the bottleneck on progress toward the control and elimination of many infectious diseases, including schistosomiasis. Questions remain about the relative costs and benefits of altering the environment to reduce infectious disease transmission. Our aim is provide the best available data to the people whose lives and livelihoods are affected, so that they can make informed choices about how to ensure a healthy future for themselves and their children.</p>
<p>[ <em>You’re smart and curious about the world. So are The Conversation’s authors and editors.</em> <a href="https://theconversation.com/us/newsletters?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=youresmart">You can read us daily by subscribing to our newsletter</a>. ]</p><img src="https://counter.theconversation.com/content/127422/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Chelsea L. Wood receives funding from the US National Science Foundation (OCE-1829509, DGE-1922004), the Alfred P. Sloan Foundation (Sloan Research Fellowship), the Western Regional Aquaculture Center (USDA, NIFA), Washington Sea Grant, Oceans Initiative, the University of Washington President's Innovation Initiative (UW Innovation Award), and the University of Washington Royalty Research Fund. </span></em></p>Schistosome worms infect hundreds of millions of people worldwide. Researchers have discovered how to use inexpensive drones to identify disease hotspots in remote African villages.Chelsea L. Wood, Assistant Professor of Aquatic and Fishery Sciences, University of WashingtonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1259062019-11-14T17:23:20Z2019-11-14T17:23:20ZA battle for the jet stream is raging above our heads<figure><img src="https://images.theconversation.com/files/301498/original/file-20191113-77320-129x3r5.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C5095%2C3813&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The northern hemisphere jet stream crossing Cape Breton Island in the Maritime Provinces of Eastern Canada.</span> <span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:STS039-601-049_Jet_Stream_(cropped).jpg">NASA/Wikimedia Commons</a></span></figcaption></figure><p>When prolonged periods of severe weather strike, two things often get the blame these days: climate change and the jet stream. Many have expressed concerns that the rapidly melting Arctic is now disturbing the jet stream, bringing more frequent bouts of wild weather. But potentially even more powerful changes are afoot in the tropics – and the consequences could be severe.</p>
<p>The northern hemisphere’s jet stream is a current of fast-moving air encircling the globe from west to east in the middle latitudes – the zone between the baking tropics and the freezing Arctic. The strongest winds are about ten kilometres high, near the altitudes at which planes fly, but the bottom of the jet can reach all the way down to the ground, forming the prevailing westerly winds familiar to many. The southern hemisphere’s counterpart is what gives rise to the <a href="https://www.britannica.com/science/roaring-forties">Roaring Forties</a> – similarly treacherous winds between latitudes 40° and 50°.</p>
<p>The jet forms a relatively sharp dividing line between the warm tropical and cold polar air masses. The strongest winds are concentrated in a band several hundred kilometres wide. But this band is not fixed. It meanders and snakes its way around the globe, sometimes touching the edge of the tropics and at other times scraping the polar regions</p>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/301818/original/file-20191114-26250-9nuy9t.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/301818/original/file-20191114-26250-9nuy9t.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=822&fit=crop&dpr=1 600w, https://images.theconversation.com/files/301818/original/file-20191114-26250-9nuy9t.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=822&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/301818/original/file-20191114-26250-9nuy9t.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=822&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/301818/original/file-20191114-26250-9nuy9t.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1033&fit=crop&dpr=1 754w, https://images.theconversation.com/files/301818/original/file-20191114-26250-9nuy9t.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1033&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/301818/original/file-20191114-26250-9nuy9t.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1033&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">In November 2019 (top), the jet shifted southwards from its usual position (bottom), leaving the UK on the cusp of its cold side, where storms often intensify.</span>
<span class="attribution"><a class="source" href="http://www.esrl.noaa.gov/psd/">ESRL/NOAA</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>As a result, the jet can have a wide array of impacts across the hemisphere. If it passes over your location, expect to be repeatedly bombarded by the whirling storms that are carried along by it. As a recent example, the severe flooding in the North of England in November 2019 arose in part from a shift of the jet, which put the UK right in the middle of a region where storms tend to grow.</p>
<p>If the jet shifts to pass north of you, you’ll find yourself under the warm, dry zone of the atmosphere which lies south of the jet. This brings generally settled and pleasant weather in summer, but can set the scene for droughts and heatwaves. And if the jet moves south instead, you’ll be on its cold polar side, so you’d better hope this doesn’t happen too much during winter.</p>
<h2>Weather worries</h2>
<p>The jet has always varied – and has always affected our weather patterns. But now climate change is affecting our weather too. As I explore <a href="https://global.oup.com/academic/product/jet-stream-9780198828518">in my latest book</a>, it’s when the wanderings of the jet and the hand of climate change add up that we get record-breaking heatwaves, floods and droughts – but not freezes.</p>
<p>The coldest weeks of any given winter will occur when the jet brings masses of cold air directly from the polar regions. But severe though this may feel, <a href="https://iopscience.iop.org/article/10.1088/1748-9326/ab4867/meta">records show</a> that similar events in past decades were even colder than they are now. While the jet is largely doing the same as it always has, the planet-heating greenhouse gases we’ve added to our atmosphere mean that invasions of polar air these days are just that bit milder.</p>
<p>The flip side, of course, is that when the jet moves north in summer, bringing warm air from the south, we often have to endure temperatures beyond anything in living memory.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/301736/original/file-20191114-26211-k71up1.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/301736/original/file-20191114-26211-k71up1.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=398&fit=crop&dpr=1 600w, https://images.theconversation.com/files/301736/original/file-20191114-26211-k71up1.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=398&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/301736/original/file-20191114-26211-k71up1.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=398&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/301736/original/file-20191114-26211-k71up1.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=500&fit=crop&dpr=1 754w, https://images.theconversation.com/files/301736/original/file-20191114-26211-k71up1.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=500&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/301736/original/file-20191114-26211-k71up1.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=500&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Mount Everest (top middle) is so high that it grazes the jet stream, blowing snow off its peak.</span>
<span class="attribution"><a class="source" href="https://eol.jsc.nasa.gov/SearchPhotos/photo.pl?mission=ISS008&roll=E&frame=13304">NASA</a></span>
</figcaption>
</figure>
<p>It is clear and well understood how climate change and the jet can combine like this to cause <a href="https://doi.org/10.1029/2019GL084601">truly extreme weather events</a>. But whether climate change is directly changing the jet’s behaviour is a much harder question to answer.</p>
<p><a href="https://www.nature.com/articles/ngeo2234">Some have suggested</a> that the rapidly warming Arctic is weakening the jet, by reducing the temperature contrast between the tropical and polar air to either side of it. As a result, the jet meanders more to the north and south, and these meanders can remain fixed over one location for longer – as happened when the <a href="https://theconversation.com/beast-from-the-east-and-freakishly-warm-arctic-temperatures-are-no-coincidence-92774">“Beast from the East”</a> placed much of Northern Europe under a bitter chill.</p>
<p>There are certainly some interesting ideas here, but many still <a href="https://science.sciencemag.org/content/343/6172/729">do not find the logic compelling</a>, and more convincing evidence from observations and computer models will be needed for these theories to become widely accepted.</p>
<p>Scientists are however increasingly confident that important changes are afoot in the tropics. Driven by the vast quantities of energy pouring in from the Sun directly overhead, these are the great powerhouses of Earth’s climate. Indeed, the power of the tropics is evident in the <a href="https://www.metoffice.gov.uk/research/climate/seasonal-to-decadal/gpc-outlooks/el-nino-la-nina/enso-impacts">worldwide weather disruption</a> caused by <a href="https://www.esrl.noaa.gov/psd/enso/">El Niño</a> events – subtle increases or decreases in temperatures in the equatorial Pacific Ocean, that in turn disturb the jet stream.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/300340/original/file-20191105-88368-yn9lp9.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/300340/original/file-20191105-88368-yn9lp9.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/300340/original/file-20191105-88368-yn9lp9.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/300340/original/file-20191105-88368-yn9lp9.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/300340/original/file-20191105-88368-yn9lp9.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/300340/original/file-20191105-88368-yn9lp9.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/300340/original/file-20191105-88368-yn9lp9.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">If El Niño causes equatorial Pacific Ocean temperatures to warm, the jet stream brings stormier weather in winter.</span>
<span class="attribution"><a class="source" href="https://www.esrl.noaa.gov/psd/enso/">climate.gov</a></span>
</figcaption>
</figure>
<p>Over the past few years, it has become apparent that at high altitudes, the Earth’s tropical regions are <a href="https://doi.org/10.1002/grl.50465">heating up more quickly than the rest of the world</a>. At least partly because of this, the tropical regions of the atmosphere have been widening, expanding ever so slightly away from the equator, and impinging more on the jet stream. </p>
<h2>Tug of war</h2>
<p>We are in the early days of a great battle in the air above our heads between the Arctic and the tropics, for the future of the jet stream. At best, there might be a stalemate, leaving the jet stream <a href="https://www.nature.com/articles/s41586-019-1465-z">distorted</a> but otherwise unmoved.</p>
<p>However, if one of the competitors outweighs the other, regional climate patterns could be severely altered as the climate zones shift along with the jet. It’s too early to say with any confidence which of these will win out, but many computer models predict the jet will <a href="https://doi.org/10.1175/JCLI-D-12-00536.1">shift a little towards the pole</a>, consistent with a greater influence of the tropics. </p>
<p>In this case, we should expect to see the warm, dry regions at the edge of the tropics extend a little further out from the equator. The strongest impacts of this would likely be felt in regions such as the <a href="https://iopscience.iop.org/article/10.1088/1748-9326/10/10/104012/meta">Mediterranean</a>, which are already highly sensitive to fluctuations in rainfall. A northward jet shift would act to steer much needed rainstorms towards central Europe instead, leaving the Mediterranean at greater risk of drought.</p>
<p>So, the jet may not become more erratic as the Arctic warms, but it may well change profoundly. And one thing is clear: the stress of increased temperatures and altered rainfall patterns from our destabilising climate will leave us even more vulnerable to the weather patterns brought by the whim of the wandering jet stream.</p>
<hr>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=140&fit=crop&dpr=1 600w, https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=140&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=140&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=176&fit=crop&dpr=1 754w, https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=176&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=176&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
</figcaption>
</figure>
<p><em><a href="https://theconversation.com/imagine-newsletter-researchers-think-of-a-world-with-climate-action-113443?utm_source=TCUK&utm_medium=linkback&utm_campaign=TCUKengagement&utm_content=Imagineheader1125906">Click here to subscribe to our climate action newsletter. Climate change is inevitable. Our response to it isn’t.</a></em></p><img src="https://counter.theconversation.com/content/125906/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Tim recently published a popular science book 'Jet Stream: A Journey Through our Changing Climate', which provides an introduction to weather and climate dynamics for a lay audience, and discusses the ways in which climate change is affecting the jet and our weather patterns. Tim Woollings receives funding from the UK Natural Environment Research Council.</span></em></p>The jet stream is being distorted on both sides by fast-warming tropical and Arctic air. Should the tropics win out, weather patterns could change profoundly.Tim Woollings, Associate Professor in Physical Climate Science, University of OxfordLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1208252019-09-09T20:10:21Z2019-09-09T20:10:21ZUrban growth, heat islands, humidity, climate change: the costs multiply in tropical cities<figure><img src="https://images.theconversation.com/files/291396/original/file-20190909-175696-3j3ype.jpg?ixlib=rb-1.1.0&rect=0%2C123%2C1581%2C935&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">During a heatwave in late 2018, Cairns temperatures topped 35°C nine days in a row and sensors at some points in the CBD recorded 45°C. </span> </figcaption></figure><p>Some <a href="https://www.un.org/en/ecosoc/integration/pdf/fact_sheet.pdf">60% of the planet’s expected urban area by 2030</a> is yet to be built. This forecast highlights how rapidly the world’s people are becoming urban. Cities now occupy about 2% of the world’s land area, but are home to about <a href="https://www.un.org/development/desa/en/news/population/2018-revision-of-world-urbanization-prospects.html">55% of the world’s people</a> and generate more than <a href="http://nua.unhabitat.org/details1.asp?ProjectId=33&ln=1">70% of global GDP</a>, plus the associated <a href="https://www.un.org/en/climatechange/cities-pollution.shtml">greenhouse gas emissions</a>.</p>
<p>So what does this mean for people who live in the tropical zones, where <a href="https://www.sciencemag.org/news/2014/06/expanding-tropics-will-play-greater-global-role-report-predicts">40% of the world’s population lives</a>? On current trends, this figure will rise to 50% by 2050. With <a href="https://sustainabledevelopment.un.org/content/documents/974736_Ziembicki%20et%20al._Implications%20of%20an%20expanding%20and%20intensifying%20tropical%20zone%20for%20the%20sustainable%20development%20agenda.pdf">tropical economies growing some 20% faster</a> than the rest of the world, the result is a swift expansion of tropical cities.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/290236/original/file-20190830-115397-n616fu.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/290236/original/file-20190830-115397-n616fu.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/290236/original/file-20190830-115397-n616fu.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=387&fit=crop&dpr=1 600w, https://images.theconversation.com/files/290236/original/file-20190830-115397-n616fu.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=387&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/290236/original/file-20190830-115397-n616fu.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=387&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/290236/original/file-20190830-115397-n616fu.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=486&fit=crop&dpr=1 754w, https://images.theconversation.com/files/290236/original/file-20190830-115397-n616fu.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=486&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/290236/original/file-20190830-115397-n616fu.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=486&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Population and number of cities of the world, by size class, 1990, 2018 and 2030.</span>
<span class="attribution"><a class="source" href="https://population.un.org/wup/Publications/">World Urbanization Prospects 2018, United Nations DESA Population Division</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/healthy-happy-and-tropical-worlds-fastest-growing-cities-demand-our-attention-112069">Healthy, happy and tropical – world's fastest-growing cities demand our attention</a>
</strong>
</em>
</p>
<hr>
<p>The populations of these growing tropical cities already experience high temperatures made worse by high humidity. This means they are highly vulnerable to extreme heat events as a result of climate change. </p>
<p>For example, extremely hot weather overwhelmed Cairns last summer. By December 3 2018, the city had recorded temperatures above 35°C nine days in a row. Four consecutive days were above 40°C.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/289316/original/file-20190825-170935-9uanh3.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/289316/original/file-20190825-170935-9uanh3.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=253&fit=crop&dpr=1 600w, https://images.theconversation.com/files/289316/original/file-20190825-170935-9uanh3.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=253&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/289316/original/file-20190825-170935-9uanh3.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=253&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/289316/original/file-20190825-170935-9uanh3.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=317&fit=crop&dpr=1 754w, https://images.theconversation.com/files/289316/original/file-20190825-170935-9uanh3.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=317&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/289316/original/file-20190825-170935-9uanh3.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=317&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Cairns’ heatwave summer.</span>
<span class="attribution"><span class="source">Authors, using BOM temperature data</span></span>
</figcaption>
</figure>
<p>For our research, temperature and humidity sensors were strategically placed in the Cairns CBD to represent people’s experience of weather at street level. These recorded temperatures consistently higher than the Bureau of Meteorology (BoM) recordings, reaching 45°C at some points.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/291224/original/file-20190906-175682-1p2r1by.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/291224/original/file-20190906-175682-1p2r1by.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/291224/original/file-20190906-175682-1p2r1by.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=650&fit=crop&dpr=1 600w, https://images.theconversation.com/files/291224/original/file-20190906-175682-1p2r1by.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=650&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/291224/original/file-20190906-175682-1p2r1by.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=650&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/291224/original/file-20190906-175682-1p2r1by.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=817&fit=crop&dpr=1 754w, https://images.theconversation.com/files/291224/original/file-20190906-175682-1p2r1by.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=817&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/291224/original/file-20190906-175682-1p2r1by.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=817&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Highest temperatures recorded by James Cook University weather data sensors during the November-December 2018 heatwave in Cairns.</span>
<span class="attribution"><span class="source">Image: Bronson Philippa</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Local effects magnify heatwave impacts</h2>
<p>Urban environments in general are hotter than non-urbanised surroundings that are covered by vegetation. The trapping of heat in cities, known as the <a href="https://www.nationalgeographic.org/encyclopedia/urban-heat-island/">urban heat island</a> effect, has impacts on human health, animal life, social events, tourism, water availability and business performance. </p>
<p>The urban heat island effect intensifies the impacts of increasing heatwaves on cities as a result of climate change.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/291226/original/file-20190906-175678-la15cl.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/291226/original/file-20190906-175678-la15cl.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/291226/original/file-20190906-175678-la15cl.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=1002&fit=crop&dpr=1 600w, https://images.theconversation.com/files/291226/original/file-20190906-175678-la15cl.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=1002&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/291226/original/file-20190906-175678-la15cl.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=1002&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/291226/original/file-20190906-175678-la15cl.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1259&fit=crop&dpr=1 754w, https://images.theconversation.com/files/291226/original/file-20190906-175678-la15cl.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1259&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/291226/original/file-20190906-175678-la15cl.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1259&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Projections of increased heatwave frequency for Cairns region using visualisation platform on Queensland Future Climate Dashboard.</span>
<span class="attribution"><a class="source" href="https://app.longpaddock.qld.gov.au/dashboard/#responseTab2">Queensland Future Climate Dashboard/Queensland Government</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>But it is important to remember that other local factors also influence these impacts. These include the scale, shape, materials, composition and growth of the built environment in a particular location and its surrounding areas. </p>
<p>The differences between the BoM data recorded at Cairns airport and the inner-city recordings show the impacts of urban expansion patterns, built form and choice of materials in tropical cities. </p>
<p>The linear layout of Cairns has, on one hand, enabled the formation of attractive places for commercial activities. As these activity centres evolve into focal points of urban life, they in turn influence all sorts of socioeconomic parameters. </p>
<p>On the other hand, the form the built environment takes changes the patterns of wind, sun and shade. These changes alter the urban <a href="https://theconversation.com/city-temperatures-and-city-economics-a-hidden-relationship-between-sun-and-wind-and-profits-116064">microclimate</a> by trapping heat and slowing or channelling air movements.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/289318/original/file-20190825-170910-sjsrqt.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/289318/original/file-20190825-170910-sjsrqt.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=500&fit=crop&dpr=1 600w, https://images.theconversation.com/files/289318/original/file-20190825-170910-sjsrqt.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=500&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/289318/original/file-20190825-170910-sjsrqt.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=500&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/289318/original/file-20190825-170910-sjsrqt.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=629&fit=crop&dpr=1 754w, https://images.theconversation.com/files/289318/original/file-20190825-170910-sjsrqt.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=629&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/289318/original/file-20190825-170910-sjsrqt.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=629&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The layout and structures of Cairns CBD alter local microclimates by trapping heat and altering air flows.</span>
<span class="attribution"><span class="source">State of Queensland 2019</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/city-temperatures-and-city-economics-a-hidden-relationship-between-sun-and-wind-and-profits-116064">City temperatures and city economics, a hidden relationship between sun and wind and profits</a>
</strong>
</em>
</p>
<hr>
<h2>Shifting the focus to the tropics</h2>
<p>To date, a large body of research has explored the undesired consequences of climate change and urban heat islands. However, the focus has been on capital and metropolitan cities with <a href="https://link.springer.com/article/10.1007/s00704-015-1703-8">humid continental climates</a>. Not many studies have looked at the economic and social impacts in the tropical context, where hot and humid conditions create extra heat stress. </p>
<p>Add the combined effects of climate change and urban heat islands and what are the socio-economic consequences of heatwaves in a tropical city like Cairns? We see that climate change adds another dimension to the relationship between cities, economic growth and development. </p>
<p>This presents a huge opportunity to start thinking about building cities that are not superficially greenwashed, but which instead tackle pressing issues such as climate variability and create sustainable business and social destinations. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/requiem-or-renewal-this-is-how-a-tropical-city-like-darwin-can-regain-its-cool-102839">Requiem or renewal? This is how a tropical city like Darwin can regain its cool</a>
</strong>
</em>
</p>
<hr>
<p>In cold climates, heatwaves and urban heat islands are not necessarily undesired, but their negative impacts are more obvious and harmful in warmer climates. And these harmful impacts of heatwaves on our economy, environment and society are on the rise. </p>
<p>We have scientific evidence of the increasing length, frequency and intensity of heatwaves. The number of record hot days in Australia has <a href="https://www.climatecouncil.org.au/uploads/9901f6614a2cac7b2b888f55b4dff9cc.pdf">doubled in the past five decades</a>.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/289313/original/file-20190825-170956-trlr9q.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/289313/original/file-20190825-170956-trlr9q.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/289313/original/file-20190825-170956-trlr9q.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/289313/original/file-20190825-170956-trlr9q.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/289313/original/file-20190825-170956-trlr9q.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/289313/original/file-20190825-170956-trlr9q.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/289313/original/file-20190825-170956-trlr9q.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Projections of changes in heatwave frequency for northern Queensland in 2030 and 2070.</span>
<span class="attribution"><a class="source" href="https://app.longpaddock.qld.gov.au/dashboard/#responseTab2">Queensland Future Climate Dashboard/Queensland Government</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>What are the costs of heatwaves?</h2>
<p>Increased exposure to heatwaves amplifies the adverse economic impacts on industries that are reliant on the health of their outdoor workers. This is in addition to the extreme heat-related fatalities and health-care costs of heatwave-related medical emergencies. As a <a href="https://www.nccarf.edu.au/localgov/resources/protecting-human-health-and-safety-during-severe-and-extreme-heat-events-national">PwC report to the Commonwealth</a> on extreme heat events stated:</p>
<blockquote>
<p>Heatwaves kill more Australians than any other natural disaster. They have received far less public attention than cyclones, floods or bushfires — they are private, silent deaths, which only hit the media when morgues reach capacity or infrastructure fails. </p>
</blockquote>
<p>Heat also has direct impacts on economic production. A <a href="https://www.researchgate.net/publication/45660010_Temperatures_and_cyclones_strongly_associated_with_economic_production_in_the_Caribbean_and_Central_America">2010 study</a> found a 1°C increase resulted in a 2.4% reduction in non-agricultural production and a 0.1% reduction in agricultural production in 28 Caribbean-basin countries. Another <a href="https://papers.ssrn.com/sol3/papers.cfm?abstract_id=2099798">study in 2012</a> found an 8% weekly loss of production when the temperature exceeded 32°C for six days in a row.</p>
<p>The 2017 <a href="http://www.agriculture.gov.au/abares/research-topics/climate/farm-performance-climate">Farm performance and climate</a> report by the <a href="http://www.agriculture.gov.au/abares">Australian Bureau of Agricultural and Resource Economics and Sciences (ABARES)</a> states:</p>
<blockquote>
<p>The recent changes in climate have had a significant negative effect on the productivity of Australian cropping farms, particularly in southwestern Australia and southeastern Australia. </p>
</blockquote>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/291232/original/file-20190906-175682-1k3i4mj.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/291232/original/file-20190906-175682-1k3i4mj.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/291232/original/file-20190906-175682-1k3i4mj.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=374&fit=crop&dpr=1 600w, https://images.theconversation.com/files/291232/original/file-20190906-175682-1k3i4mj.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=374&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/291232/original/file-20190906-175682-1k3i4mj.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=374&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/291232/original/file-20190906-175682-1k3i4mj.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=470&fit=crop&dpr=1 754w, https://images.theconversation.com/files/291232/original/file-20190906-175682-1k3i4mj.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=470&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/291232/original/file-20190906-175682-1k3i4mj.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=470&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Average climate effect on productivity of cropping farms in southwestern and southeastern Australia since 2000–01 (relative to average conditions from 1914–15 to 2014–15).</span>
<span class="attribution"><a class="source" href="http://www.agriculture.gov.au/abares/research-topics/climate/farm-performance-climate">Farm performance and climate, ABARES</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>It’s not just farming that is vulnerable. A <a href="https://www.climatechange.vic.gov.au/__data/assets/pdf_file/0011/413030/The-economic-impact-of-heatwaves-on-Victoria.pdf">Victorian government report</a> report this year estimated an extreme heatwave event costs the state’s construction sector A$103 million. The impact of heatwaves on the city of Melbourne’s economy is estimated at A$52.9 million a year on average. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/290239/original/file-20190830-115391-128cd7z.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/290239/original/file-20190830-115391-128cd7z.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/290239/original/file-20190830-115391-128cd7z.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=427&fit=crop&dpr=1 600w, https://images.theconversation.com/files/290239/original/file-20190830-115391-128cd7z.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=427&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/290239/original/file-20190830-115391-128cd7z.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=427&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/290239/original/file-20190830-115391-128cd7z.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=537&fit=crop&dpr=1 754w, https://images.theconversation.com/files/290239/original/file-20190830-115391-128cd7z.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=537&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/290239/original/file-20190830-115391-128cd7z.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=537&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Impacts of heatwaves on Victoria’s main economic sectors.</span>
<span class="attribution"><a class="source" href="https://www.climatechange.vic.gov.au/__data/assets/pdf_file/0011/413030/The-economic-impact-of-heatwaves-on-Victoria.pdf">State of Victoria Department of Environment, Land, Water and Planning</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>According to this report, economic costs increase exponentially as the severity of heatwaves increases. This has obvious implications for cities in tropical regions.</p>
<p>As the next step in <a href="https://www.researchgate.net/project/Evidence-based-Economic-Assessment-of-Urban-Comfort">our research</a>, we are examining the relationship between local urban features, urban heat islands, the resulting city temperatures and their direct and indirect (spillover) effects on local and regional economic activities.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/making-a-global-agenda-work-locally-for-healthy-sustainable-living-in-tropical-australia-97069">Making a global agenda work locally for healthy, sustainable living in tropical Australia</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/120825/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>The world’s fastest-growing cities are in the tropics. They are highly exposed to climate change, especially as urban heat island effects and humidity magnify the impacts of increasing heatwaves.Taha Chaiechi, Senior Lecturer, James Cook UniversitySilvia Tavares, Lecturer in Urban Design, James Cook UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1160642019-06-13T20:16:05Z2019-06-13T20:16:05ZCity temperatures and city economics, a hidden relationship between sun and wind and profits<figure><img src="https://images.theconversation.com/files/273313/original/file-20190508-183096-18h80td.JPG?ixlib=rb-1.1.0&rect=1268%2C0%2C3483%2C1922&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Cairns Lagoon: as a good response to the tropical climate, it's a very active place but with little business activity.</span> <span class="attribution"><span class="source">Silvia Tavares</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Urban design undoubtedly influences the urban economy. A simple thing like designing an area to make it more walkable can boost local business profits. This can also increase real estate value, <a href="http://www.downtowndevelopment.com/pdf/baltimore_Dec20.pdf">create more and better jobs</a> and <a href="https://www.smartgrowthamerica.org/app/legacy/documents/foot-traffic-ahead.pdf">generate stronger local economies</a>. </p>
<p>Street temperatures also determine their walkability. With climate change bringing <a href="https://app.longpaddock.qld.gov.au/heatwave">longer and more frequent heatwaves</a>, street temperatures will become even higher than at present. This will reduce walkability and, in turn, local business profitability. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/smart-urban-design-could-save-lives-in-future-heatwaves-33246">Smart urban design could save lives in future heatwaves</a>
</strong>
</em>
</p>
<hr>
<h2>Walkability impacts local businesses</h2>
<p>The evidence shows businesses do better with foot traffic than car-based mobility. For example, closing New York’s Times Square to cars <a href="https://broadway.showtickets.com/articles/secrets-of-times-square/">increased business revenue by 71% during an eight-month pilot project in 2009</a>.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/LujWrkYsl64?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">New York transport commissioner Janette Sadik-Khan explains the impact on street and retail activity of the transformation of Times Square.</span></figcaption>
</figure>
<p>The following example helps explain why foot traffic benefits local business. In car-based cities, a take-away coffee on the way to work may involve a series of decisions:</p>
<ol>
<li>driving the car to a certain cafe</li>
<li>finding car parking</li>
<li>leaving and closing the car</li>
<li>joining a queue to buy a coffee</li>
<li>getting back in the car </li>
<li>proceeding on the journey to work. </li>
</ol>
<p>In contrast, when walking down the street we may not even have considered having a coffee, but we can smell it. So: </p>
<ol>
<li>we walk into the cafe</li>
<li>join the queue to buy a coffee</li>
<li>carry on walking to work. </li>
</ol>
<p>The process is shorter, more spontaneous and part of a daily journey. Impulse buys as a result of exposure to stimuli have surprisingly big economic consequences, particularly for the retail industry. </p>
<h2>What is microclimate?</h2>
<p>Microclimate refers to the atmospheric conditions in an area. These can vary not only from the surrounding region but also within the area itself. Both the natural and built environments influence these differences. A well-known example of such differences is in <a href="https://www.abc.net.au/news/2018-03-01/how-western-sydney-is-tackling-the-heat-island-effect/9361156">Sydney’s western suburbs</a>, which are <a href="https://theconversation.com/building-cool-cities-for-a-hot-future-57489">much hotter in summer than the eastern suburbs</a>, which benefit from being close to the sea and cooling breezes. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-people-can-best-make-the-transition-to-cool-future-cities-80683">How people can best make the transition to cool future cities</a>
</strong>
</em>
</p>
<hr>
<p>But can an unpleasant microclimate suppress impulse buys? To a certain extent, yes. The frequency of impulse buys, and ultimately the overall success of most businesses in tropical cities, may be connected to the local microclimate.</p>
<p>For instance, the orientation of streets in relation to sun and breeze exposure can influence the microclimate. This can then determine if people stay and have a second coffee or extra ice cream after lunch, or if they avoid streets because they are too exposed and hot. </p>
<p>Australian cities, however, are too often overzoned and planned in a sprawling pattern. By compromising walkability this represses spontaneous purchases. </p>
<p>CBDs are also too frequently oversized with unshaded wide streets. In hot climates this makes the journey on foot unpleasant and poses health risks to young children, senior citizens and people with health conditions. </p>
<h2>Microclimates and the tropics</h2>
<p>To date, a growing body of research on this question has <a href="https://www.richmondfed.org/-/media/richmondfedorg/publications/research/economic_brief/2018/pdf/eb_18-08.pdf">focused mainly on capital and metropolitan cities with humid continental climates</a>. The assumption is that those cities are more vulnerable to the effects of higher temperatures. However, looking only at these kinds of cities can lead us to overlook important variations. </p>
<p>Coastal tropical cities can also experience unpleasant microclimates. While the tropics are seen as perfect holiday locations, high summer temperatures can compromise street life. </p>
<p>The <a href="https://theconversation.com/building-cool-cities-for-a-hot-future-57489">qualities and materials of buildings and infrastructure</a> such as roads and footpaths also influence local temperatures. Large areas of hard, heat-absorbing surfaces contribute to the <a href="https://www.theguardian.com/sustainable-business/2017/feb/21/urban-heat-islands-cooling-things-down-with-trees-green-roads-and-fewer-cars">urban heat island effect</a>, which makes urban areas hotter than their surroundings. The effects of this on urban life and economic activities become more critical in hot and humid tropical conditions.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/building-cool-cities-for-a-hot-future-57489">Building cool cities for a hot future</a>
</strong>
</em>
</p>
<hr>
<h2>Taking advantage of microclimates</h2>
<p>In essence, microclimate affects the use of the footpath. If the microclimate discourages the use of public space, then a great design may not be enough to create the type of environment that attracts street life and generates strong local economic activity.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/273315/original/file-20190508-183103-fi602e.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/273315/original/file-20190508-183103-fi602e.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/273315/original/file-20190508-183103-fi602e.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/273315/original/file-20190508-183103-fi602e.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/273315/original/file-20190508-183103-fi602e.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/273315/original/file-20190508-183103-fi602e.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/273315/original/file-20190508-183103-fi602e.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Shields and Lake Street corner in Cairns: great design, plenty of trees and shade, but little activation.</span>
<span class="attribution"><span class="source">Silvia Tavares</span></span>
</figcaption>
</figure>
<p>Considering this problem, <a href="https://www.researchgate.net/project/Evidence-based-Economic-Assessment-of-Urban-Comfort">our ongoing research</a> focuses on tropical cities. We are investigating the relationship between urban microclimate, labour productivity, sales revenue and real estate values. </p>
<p>Is there, for instance, an optimum location for certain types of land use according to their suitability and need to use the footpath? If one side of the street is more exposed to the sun than the other, it may be more suitable for establishments that don’t make active use of the streetscape, such as stores and offices, rather than cafes and restaurants. </p>
<p>Another question is does microclimate affect the productivity of businesses differently across urban and non-urban surroundings? </p>
<p>Part of the solution to rising urban temperatures could focus on street orientation and exposure to breezes. Priority could be given to siting cafes, for instance, in pleasant areas, with tables outside to help activate spaces. Instead of creating zoning that kills flexibility and dynamic spaces, planning guidelines for tropical street life should consider the types of businesses suited to specific street microclimates. </p>
<p>In a warming climate, designing for microclimate is more important than ever before to ensure urban life and economies can prosper. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-to-build-a-city-fit-for-50-heatwaves-49560">How to build a city fit for 50℃ heatwaves</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/116064/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Good urban design and walkability boost local economic activity by increasing public activity, but cities need to pay more attention to the effects of microclimates on streets and public spaces.Silvia Tavares, Lecturer in Urban Design, James Cook UniversityTaha Chaiechi, Senior Lecturer, James Cook UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1120692019-03-27T18:40:51Z2019-03-27T18:40:51ZHealthy, happy and tropical – world’s fastest-growing cities demand our attention<figure><img src="https://images.theconversation.com/files/264513/original/file-20190319-28468-17lwede.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Marine Drive in Mumbai, viewed here from across Chowpatty Beach, is an 'accidental' planning legacy that's now one of the most popular places in the city.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/chowpatty-beach-mumbai-india-skyline-photo-49318582">Dirk Ott/Shutterstock</a></span></figcaption></figure><p>What does it take to be a happy and healthy city? In any city, myriad factors go into the mix – and of course we are not dealing with just one kind of city. But, due to the world history of colonisation, models are still too often European-centric. In particular, we need to adjust how we think about cities in the tropics. </p>
<p>For a start, <a href="https://en.wikipedia.org/wiki/Tropics">almost half of the world’s population lives in the tropics</a> and <a href="https://www.jcu.edu.au/state-of-the-tropics/project/10-reasons">more than half of the world’s children</a>. This makes it the <a href="https://www.weforum.org/agenda/2018/05/why-the-world-s-fastest-growing-populations-are-in-the-middle-east-and-%20africa/">fastest-growing region on the planet</a>. The pace of <a href="https://www.jcu.edu.au/state-of-the-tropics/project/10-reasons">economic and technological development is fastest in the tropics</a>, too.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-the-world-is-turning-tropical-before-our-eyes-26973">How the world is turning tropical before our eyes</a>
</strong>
</em>
</p>
<hr>
<p>The tropics are also home to the <a href="https://www.jcu.edu.au/state-of-the-tropics/project/10-reasons">greatest diversity</a> of architectural styles and urban places. Sandwiched between the Tropic of Cancer and the Tropic of Capricorn, nearly 50 countries display singular <a href="https://www.foreground.com.au/cities/tropical-urbanism/">tropical urbanism</a>, which reflects first settlements, colonial history and the more friendly contact with other cultures. Nowhere else on Earth can we see such a mingling of vernacular, pre-Columbian, Gothic, Baroque, Renaissance and Modernist buildings and urban plans.</p>
<p>Designing for the tropics differs considerably from designing for temperate areas. The climate can be very hot and humid, causing extreme discomfort for city residents.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/requiem-or-renewal-this-is-how-a-tropical-city-like-darwin-can-regain-its-cool-102839">Requiem or renewal? This is how a tropical city like Darwin can regain its cool</a>
</strong>
</em>
</p>
<hr>
<p>Of course, they too aspire to the good health and well-being that have been promoted as being at the heart of urbanisation from the 18th-century hygienists onwards. Sustainable development entered the picture in the 20th century – the 1987 <a href="http://www.un-documents.net/our-common-future.pdf">Brundtland Report</a> coined the term. </p>
<p>Paul James took sustainable development beyond the original social-economic-environmental triad with the <a href="http://www2.abruem.org.br/wp-content/uploads/2017/11/2015_James-Urban-Sustainability.pdf">circles of sustainability</a>. This draws attention to other significant elements, including culture (e.g. creativity, belief and meaning, etc.) and politics (e.g. organisation and governance, dialogue and reconciliation, etc.). </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/264511/original/file-20190319-28468-1cifj5s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/264511/original/file-20190319-28468-1cifj5s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/264511/original/file-20190319-28468-1cifj5s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=578&fit=crop&dpr=1 600w, https://images.theconversation.com/files/264511/original/file-20190319-28468-1cifj5s.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=578&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/264511/original/file-20190319-28468-1cifj5s.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=578&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/264511/original/file-20190319-28468-1cifj5s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=727&fit=crop&dpr=1 754w, https://images.theconversation.com/files/264511/original/file-20190319-28468-1cifj5s.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=727&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/264511/original/file-20190319-28468-1cifj5s.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=727&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Paul James developed the concept of circles of sustainability that incorporate elements of politics and culture (this one represents Melbourne in 2011).</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Circles_of_Sustainability">SaintGeorgeIV/Wikipedia</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<h2>How do cities achieve all these goals?</h2>
<p>With the prominence of good health and well-being in the <a href="http://habitat3.org/wp-content/uploads/NUA-English-With-Index-1.pdf">New Urban Agenda</a> and UN <a href="https://sustainabledevelopment.un.org/?menu=1300">Sustainable Development Goals</a>, cities are paying more attention to well-being and <a href="http://happyplanetindex.org/">happiness indexes</a> and reports. So how exactly can urban design and experience design – the design of how the visitor will live, appreciate and remember the place – <a href="http://worldhappiness.report/ed/2018/">enhance well-being and happiness</a> in the world’s growing cities? </p>
<p>The Healthy Happy Cities in Tropical Environment (<a href="https://healthy-happy-cities-in-a-tropical-environment-66.webself.net/">HHCTE</a>) network was founded in 2018 to investigate these questions and report on best practices, as well as providing for critical exchange through workshops and conferences. Recently, at the inaugural two-day HHCTE workshop, urban researchers, professionals, civil society actors and decision-makers came together to identify challenges in achieving happy healthy cities in tropical environments and to propose solutions. Several significant findings emerged.</p>
<p>Firstly, and very fortunately, we can learn from many examples of best practice in urban design all around the world. These range from free public open-air swimming pools (e.g. in Cairns and Brisbane, both in Australia) to <a href="http://www.gardensbythebay.com.sg/en.html">Gardens by the Bay</a> in Singapore and <a href="https://www.mumbai.org.uk/marine-drive/marine-drive.html">Mumbai Marine Drive</a> in India. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/265497/original/file-20190325-36276-x2u5fm.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/265497/original/file-20190325-36276-x2u5fm.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/265497/original/file-20190325-36276-x2u5fm.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/265497/original/file-20190325-36276-x2u5fm.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/265497/original/file-20190325-36276-x2u5fm.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/265497/original/file-20190325-36276-x2u5fm.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/265497/original/file-20190325-36276-x2u5fm.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/265497/original/file-20190325-36276-x2u5fm.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Gardens by the Bay in Singapore is an outstanding example of urban design for a tropical city.</span>
<span class="attribution"><span class="source">Pasi Virtamo</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/making-a-global-agenda-work-locally-for-healthy-sustainable-living-in-tropical-australia-97069">Making a global agenda work locally for healthy, sustainable living in tropical Australia</a>
</strong>
</em>
</p>
<hr>
<p>However, when prompted to identify and describe the processes and principles that delivered such successful urban designs, HHCTE participants articulated very few of these clearly. This can partly explain why we so often face problems with transferring models or principles (besides the change of context, local features, etc.). It demonstrates how the understanding of experiences might be difficult to access and express. This sort of communication needs to be developed.</p>
<p>Second, we all come with bias. Our cultural background might determine, for example, whether it is important to have free or consumption-based urban experiences. For instance, for some the quality of shading and sitting areas through the journey from one place to another might be plenty, while for others the opening of a bright new shopping mall might symbolise a great urban experience.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/265498/original/file-20190325-36267-1o8hooe.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/265498/original/file-20190325-36267-1o8hooe.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/265498/original/file-20190325-36267-1o8hooe.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/265498/original/file-20190325-36267-1o8hooe.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/265498/original/file-20190325-36267-1o8hooe.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/265498/original/file-20190325-36267-1o8hooe.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/265498/original/file-20190325-36267-1o8hooe.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/265498/original/file-20190325-36267-1o8hooe.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Pacific Fair on the Gold Coast, one of Queensland’s largest shopping centres, puts the focus on providing an urban experience.</span>
<span class="attribution"><span class="source">Karine Dupre</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>The idea that urban design should cater for multicultural diversity is not new, but the emphasis on money-based urban experiences raises questions about the role and meaningfulness of public spaces. Is this a shift from our traditional paradigm?</p>
<p>Third, when asked “what makes you feel happy and healthy in the city?”, all groups of participants, without exception, mentioned ease of walking, bike paths, greenery, public transport and safety. These urban infrastructures really do matter for everyone. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/cities-can-grow-without-wrecking-reefs-and-oceans-heres-how-107263">Cities can grow without wrecking reefs and oceans. Here's how</a>
</strong>
</em>
</p>
<hr>
<p>But then, surprisingly, all participants seemed to don their urban designer hats and forgot to express their more personal feelings. The aim seemed to be to use a neutral vocabulary, as well as trying to reach a professional identity and consensus. Yet, when back home, will everyone not dream about something else – such as colours, music, smells, <a href="https://www.tandfonline.com/doi/abs/10.1080/20507828.2015.1066996">urban atmosphere</a> and so forth – for the city they live in?</p>
<h2>What next?</h2>
<p>The main aim of participation workshops is to give voice to a variety of stakeholders and engage in bottom-up actions that lead to improvements. While we need to be aware of the <a href="https://www.sciencedirect.com/science/article/pii/B9780080450155000186">pitfalls of participation</a>, such as unbalanced processes, it remains a great tool to take the pulse of one society.</p>
<p>On the specific topic of healthy happy cities, the workshop again demonstrated that citizens have good ideas and are ready to be engaged. Yet it also showed that the broad city scale of the discussion influenced the proposals. Perhaps a discussion at the level of the house or street scales would have been closer to the heart of each participant. </p>
<p>We also learned it takes many little steps and aspirations to become a happy healthy city, all of which are feasible. What, then, are we waiting for?</p><img src="https://counter.theconversation.com/content/112069/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Karine Dupré received funding from AFRAN (Australian-French Research Association Network) for the HHCTE workshop.</span></em></p><p class="fine-print"><em><span>Jane Coulon and Silvia Tavares do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>When we plan a better future for an increasingly urbanised world, we need to be aware that more than half of all children now live in the tropics. That calls for solutions with a tropical character.Karine Dupré, Associate Professor in Architecture, Griffith UniversityJane Coulon, Lecturer, School of Architecture, Reunion branch, École Nationale Supérieure d'Architecture Montpellier (ENSAM)Silvia Tavares, Lecturer in Urban Design, James Cook UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1078802019-03-18T10:44:11Z2019-03-18T10:44:11ZRestoring tropical forests isn’t meaningful if those forests only stand for 10 or 20 years<figure><img src="https://images.theconversation.com/files/264261/original/file-20190317-28496-115eioj.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A regenerating stand of rainforest in northern Costa Rica.</span> <span class="attribution"><span class="source">Matthew Fagan</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>Tropical forests globally are being lost at a rate of <a href="https://www.wri.org/blog/2018/06/2017-was-second-worst-year-record-tropical-tree-cover-loss">61,000 square miles a year</a>. And despite conservation efforts, the global rate of loss is <a href="http://forestdeclaration.org/goal/goal-1/">accelerating</a>. In 2016 it reached a <a href="http://forestdeclaration.org/wp-content/uploads/2018/08/goal_1-stop_forest_loss%E2%80%93forest_declaration.pdf">15-year high</a>, with 114,000 square miles cleared. </p>
<p>At the same time, many countries are pledging to restore large swaths of forests. The <a href="http://www.bonnchallenge.org/">Bonn Challenge</a>, a global initiative launched in 2011, calls for national commitments to restore 580,000 square miles of the world’s deforested and degraded land by <a href="http://www.bonnchallenge.org/content/challenge">2020</a>. In 2014 the <a href="http://forestdeclaration.org/">New York Declaration on Forests</a> increased this goal to 1.35 million square miles, an area about twice the size of Alaska, by 2030. </p>
<p>Ecological restoration is a process of <a href="https://www.ser.org/page/SERStandards/International-Standards-for-the-Practice-of-Ecological-Restoration.htm">helping damaged ecosystems recover</a>. It produces many benefits for both wildlife and people – for example, better habitat, erosion control, cleaner drinking water and <a href="https://doi.org/10.1371/journal.pone.0128339">jobs</a>. </p>
<p>That’s why the Bonn Challenge is so exciting for <a href="https://scholar.google.com/citations?user=1F41tKkAAAAJ&hl=en">geographers</a> and <a href="https://scholar.google.com/citations?user=XgB4WgEAAAAJ&hl=en">ecologists</a> like <a href="https://scholar.google.com/citations?user=b5a0WscAAAAJ&hl=en">us</a>. It brings restoration into the center of global discussions about combating climate change, preventing species extinctions and improve farmers’ lives. It connects governments, organizations, companies and communities, and is catalyzing <a href="https://news.globallandscapesforum.org/26882/bonn-challenge-new-solutions-urged-for-financing-landscape-restoration/">substantial investments in forest restoration</a>.</p>
<p>However, a closer look shows that a struggle remains to fully realize the Bonn Challenge vision. Some reforestation efforts provide only limited benefits, and studies have shown that maintaining these forests for decades is critical to maximize the economic and ecological benefits of establishing them.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/264262/original/file-20190317-28505-1x4f88u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/264262/original/file-20190317-28505-1x4f88u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/264262/original/file-20190317-28505-1x4f88u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/264262/original/file-20190317-28505-1x4f88u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/264262/original/file-20190317-28505-1x4f88u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/264262/original/file-20190317-28505-1x4f88u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/264262/original/file-20190317-28505-1x4f88u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/264262/original/file-20190317-28505-1x4f88u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Reforestation project in northern Costa Rica: a plantation of native trees with valuable wood.</span>
<span class="attribution"><span class="source">Matthew Fagan</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Putting trees back on the land</h2>
<p>So far, 48 nations and 10 states and companies have made Bonn Challenge <a href="http://www.bonnchallenge.org/">commitments</a> to restore 363,000 square miles by 2020 and another 294,000 square miles by 2030. The United States and a Pakistani province have already <a href="http://forestdeclaration.org/wp-content/uploads/2018/08/goal_5-restore_forests%E2%80%93forest_declaration.pdf">fulfilled their commitments</a>, restoring a total of 67,000 square miles.</p>
<p>Restoring forests poses political and economic challenges for national governments. Letting forests grow back inevitably means pulling land out of farming. Natural forest regeneration mainly occurs where farmers have <a href="http://www.fao.org/3/a-i5588e.pdf">abandoned poor quality land</a>, or where governments discourage poor farming practices – for example, near wetlands or on steep slopes. Opportunities for natural regeneration elsewhere are limited.</p>
<p>As a result, much forest landscape restoration under the Bonn Challenge focuses on improving existing landscapes using trees. Restoration activities may include creating timber or fruit plantations; agroforestry, or planting rows of trees in and around agricultural fields; and silviculture, or improving the condition of degraded forests. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/YnAeqzffr4w?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">The U.N. Decade of Ecosystem Restoration seeks to restore some 5 billion acres of deforested and degraded landscapes and seascapes between 2021 and 2030.</span></figcaption>
</figure>
<p>One early success, the “<a href="https://infoflr.org/news-media/pakistans-billion-tree-tsunami-restores-350000-hectares-forests-and-degraded-land">Billion Tree Tsunami</a>” in Pakistan’s Khyber Pakhtunkhwa province, has exceeded its 350,000-hectare pledge through a combination of protecting forest regeneration and planting trees. Similarly, Rwanda has restored 700,000 of the 2 million hectares it pledged, primarily through agroforestry and reforesting erosion-prone areas, and <a href="https://infoflr.org/bonn-challenge-barometer/rwanda/2018/policies">created thousands of green jobs</a>. </p>
<h2>Green deserts</h2>
<p>However, these “restored forests” are often <a href="https://doi.org/10.1007/s10531-017-1356-2">poor replacements for natural habitat</a>. For animals dwelling in tropical forests, agroforestry and tree plantations can look more like <a href="https://doi.org/10.1007/s10531-010-9936-4">green deserts</a> than forests.</p>
<p>Many tropical forest wildlife species are only found in <a href="https://news.mongabay.com/2011/09/old-growth-forests-are-irreplaceable-for-sustaining-biodiversity/">mature tropical forests</a> and <a href="https://www.pnas.org/content/pnas/104/47/18555.full.pdf">cannot survive</a> in open agroforests, monoculture tree plantations or young natural regeneration. Truly restoring tropical forest habitat takes a diversity of forest species, and time. </p>
<p>Nonetheless, these working “forests” do have ecological value for some species, and can <a href="https://doi.org/10.1016/j.envsci.2015.12.010">spare remaining natural forests</a> from axes, fire and plows. In addition, scientists have estimated that restored forests could sequester up to <a href="https://doi.org/10.1073/pnas.1710465114">16 percent of the carbon</a> needed to limit global warming to less than 2 degrees Celsius above pre-industrial levels, while generating some <a href="https://www.iucn.org/downloads/policy_brief_on_forest_restoration_1.pdf">US$84 billion</a> in assets such as timber and erosion control.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/264171/original/file-20190315-28468-1l63iic.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/264171/original/file-20190315-28468-1l63iic.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=410&fit=crop&dpr=1 600w, https://images.theconversation.com/files/264171/original/file-20190315-28468-1l63iic.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=410&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/264171/original/file-20190315-28468-1l63iic.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=410&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/264171/original/file-20190315-28468-1l63iic.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=515&fit=crop&dpr=1 754w, https://images.theconversation.com/files/264171/original/file-20190315-28468-1l63iic.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=515&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/264171/original/file-20190315-28468-1l63iic.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=515&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Logging and degradation of tropical forests is the main reason why forestry and land use account for 10–15 percent of the world’s total human-induced CO2 emissions.</span>
<span class="attribution"><a class="source" href="https://farm1.staticflickr.com/601/31550389533_6de26fee78_b.jpg">GRID-Arendal</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-sa/4.0/">CC BY-NC-SA</a></span>
</figcaption>
</figure>
<h2>Restored, but for how long?</h2>
<p>Benefits for wildlife and Earth’s climate from forest restoration <a href="https://doi.org/10.1371/journal.pone.0171368">accrue over decades</a>. However, many forests are unlikely to remain protected for this long.</p>
<p>In a 2018 study we showed that forests that naturally regenerated in Costa Rica between 1947 and 2014 had <a href="https://doi.org/10.1111/conl.12607">only a 50 percent chance of enduring for 20 years</a>. Most places where forests regrew were subsequently re-cleared for farming. Twenty years represents about a quarter of the time needed for forest <a href="https://doi.org/10.1098/rspb.2013.2236">carbon stocks</a> to fully recover, and less than one-fifth of the time required for many forest-dwelling <a href="https://doi.org/10.1016/j.biocon.2009.05.035">plants and animals</a> to return.</p>
<p>Unfortunately, 20 years may be more than most new forests get. Studies in <a href="https://doi.org/10.1016/j.rse.2016.09.012">Brazil</a> and <a href="https://doi.org/10.1088/1748-9326/aa708b">Peru</a> show that regenerating forests there are re-cleared even faster, often after just a few years.</p>
<p>This problem is not limited to natural forests. Agroforests worldwide are <a href="https://assets.publishing.service.gov.uk/media/57a08d2be5274a31e00016b6/R7264_-_Jungle_Rubber.pdf">under pressure</a>. For example, until recent decades, coffee and cocoa farmers in the tropics raised their crops in agroforests under a shady canopy of trees, which mimicked the way these plants grow in nature and maximized their health. Today, however, many of them grow their crops in the sun. This method can <a href="http://revistacafeicultura.com.br/?mat=3382">improve yield</a>, but requires pesticides and fertilizer to compensate for added stress on the plants.</p>
<figure>
<iframe src="https://player.vimeo.com/video/146822547" width="500" height="281" frameborder="0" webkitallowfullscreen="" mozallowfullscreen="" allowfullscreen=""></iframe>
<figcaption><span class="caption">Poor management of coffee and cacao farming is a leading cause of deforestation in Peru. Local and international organizations are working to conserve and restore forests through better farming practices.</span></figcaption>
</figure>
<p>And although timber plantations sequester additional carbon with every harvest and replanting, their replanting is dependent on shifting market demand for wood. Once they are harvested after six to 14 years of growth, tropical timber plantations can be <a href="http://dx.doi.org/10.1088/1748-9326/8/3/034017">abandoned</a> as a <a href="http://www.fao.org/forestry/42658-0b8ddd1c5c20b4980467f2f4724f445a7.pdf">bad investment</a> and replaced with <a href="https://doi.org/10.1016/j.landusepol.2017.08.036">higher-yielding row crops or pasture</a>.</p>
<h2>Solid foundations for recovery</h2>
<p>If the Bonn Challenge is to achieve its goals, nations will have to find ways of converting short-term restoration pledges into long-term ecosystem recovery. This may require tightening the rules. </p>
<p>Some countries have pledged to protect <a href="https://doi.org/10.1111/1365-2664.13282">unrealistically large areas</a>. For example, Rwanda committed to restore 77 percent of its national territory, and Costa Rica and Nicaragua pledged to restore 20 percent of their territories apiece. Another flaw is that the Bonn Challenge does not prevent countries from <a href="https://news.mongabay.com/2014/10/forest-restoration-commitments-driven-by-science-or-politics/">deforesting some areas</a> even as they are restoring others. </p>
<p>It will be impossible to track overall progress without an international commitment to monitor and sustain <a href="https://infoflr.org/bonn-challenge-barometer">restoration successes</a>. International organizations need to invest in <a href="https://start.org/programs/gofc-gold/">satellite</a> and <a href="https://blogs.plos.org/blog/2017/06/21/participation-of-local-people-in-monitoring-forests-why-and-how/">local monitoring networks</a>. We also believe they should consider how <a href="http://forestdeclaration.org/wp-content/uploads/2018/08/goal_8-finance_for_forest_action%E2%80%93forest_declaration.pdf">large international investments</a> in sectors such as agriculture, mining and infrastructure drive forest loss and regrowth. </p>
<p>Countries like <a href="https://wri-indonesia.org/en/blog/indonesias-commitment-forests-restoration">Indonesia</a> that may be considering a Bonn Challenge pledge should be encouraged to focus on long-term impacts. Instead of restoring 10,000 square miles of one-year-old forest by 2020, why not restore 5,000 square miles of 100-year-old forest by 2120? Countries like <a href="https://infoflr.org/countries/costa-rica">Costa Rica</a> that have already pledged can lock in those gains by protecting regrown forests. </p>
<p>The U.N. General Assembly recently approved a resolution designating 2021 to 2030 as the <a href="https://news.globallandscapesforum.org/32909/un-declares-2021-to-2030-decade-on-ecosystem-restoration/">U.N. Decade of Ecosystem Restoration</a>. We hope this step will help motivate nations to keep their promises and invest in restoring Earth’s deforested and degraded ecosystems.</p><img src="https://counter.theconversation.com/content/107880/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Leighton Reid receives funding from the National Science Foundation (grant DEB-1313788). He is affiliated with the Center for Conservation and Sustainable Development at Missouri Botanical Garden.</span></em></p><p class="fine-print"><em><span>Margaret Buck Holland and Matthew Fagan do not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Many nations are restoring degraded tropical forests to slow climate change, protect endangered species and improve rural life. But those forests often are cleared again soon afterward.Matthew Fagan, Assistant Professor of Geography and Environmental Systems, University of Maryland, Baltimore CountyLeighton Reid, Faculty Associate, University of Missouri-St. LouisMargaret Buck Holland, Associate Professor, University of Maryland, Baltimore CountyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1072632018-12-10T18:55:42Z2018-12-10T18:55:42ZCities can grow without wrecking reefs and oceans. Here’s how<figure><img src="https://images.theconversation.com/files/248335/original/file-20181203-194953-1yx65zo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Cairns has lots of hard grey infrastructure but much less green infrastructure that would reduce the impacts of the city's growth.</span> <span class="attribution"><span class="source">Karine Dupré</span>, <span class="license">Author provided</span></span></figcaption></figure><p>“<a href="https://www.iyor2018.org/">What happens if the water temperature rises by a few degrees?</a>” is the 2018 <a href="https://www.icriforum.org/about-icri/iyor">International Year of the Reef</a> leading question. While the ocean is the focus, <a href="https://www.un.org/development/desa/en/news/population/2018-revision-of-world-urbanization-prospects.html">urbanisation</a> is the main reason for the rising temperatures and water pollution. Yet it receives little attention in this discussion. </p>
<p>In turn, rising temperatures <a href="https://theconversation.com/urban-floods-we-can-pay-now-or-later-96160">increase downpours and urban floods</a>, adding to the pressures on urban infrastructure. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/design-for-flooding-how-cities-can-make-room-for-water-105844">Design for flooding: how cities can make room for water</a>
</strong>
</em>
</p>
<hr>
<h2>Protecting the reef as Cairns grows</h2>
<p>Cairns is an expanding Queensland city located between two World Heritage sites – the <a href="http://www.greatbarrierreef.org/about-the-reef">Great Barrier Reef</a> and the <a href="https://en.wikipedia.org/wiki/Daintree_Rainforest">Daintree Rainforest</a>. While important research focuses on these sites themselves, not much is known about how the surrounding urban areas influence these natural environments. Similarly, little is known about how urban planning and design contribute to the health of the inner city and surrounding water bodies, including the ocean. </p>
<p>Cairns is a major Australian tourism destination with a unique coastal setting of rainforest and reef. This attracts growing numbers of visitors. One effect of this success is increased urbanisation to accommodate these tourists. </p>
<p>There are many opportunities to promote sustainable and socially acceptable growth in Cairns. Yet this growth is not without challenges. These include:</p>
<ul>
<li>impacts of climate change, including sea-level rise and ocean warming</li>
<li>lack of comprehensive urban infrastructure strategy</li>
<li>lack of comprehensive assessment of the benefits of integrated urban design to maximise coastal resilience and the health of streams and oceans. </li>
</ul>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/249156/original/file-20181206-186055-r0mm58.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/249156/original/file-20181206-186055-r0mm58.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/249156/original/file-20181206-186055-r0mm58.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=900&fit=crop&dpr=1 600w, https://images.theconversation.com/files/249156/original/file-20181206-186055-r0mm58.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=900&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/249156/original/file-20181206-186055-r0mm58.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=900&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/249156/original/file-20181206-186055-r0mm58.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1131&fit=crop&dpr=1 754w, https://images.theconversation.com/files/249156/original/file-20181206-186055-r0mm58.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1131&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/249156/original/file-20181206-186055-r0mm58.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1131&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Rain gardens are common in Singapore.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/rogersoh/4742030401/in/photolist-8e39qR-8cTrF9-5ZVakG-6SD8Xr-dYNhd-5ZVULb-5ZVkTj-9WFvAV-d39rTQ-9WFtHH-9WJmQ1-9WFvgn-ojCd4B-8e3c2R-ojCdzB-5ZVUtA-5ZV7BU-8ur9JW-9SnZ4W-ov8N8x-9WFwY6-5ZV8Nf-c5y1kE-uLxdpo-o1nqXY-9WFwaa-ohFgoE-ot6Rgd-55jr8c-7jH9xY-2mMoCW-fVdLWn-6zSj5d-94ndL2-omyHjz-fzRSHi-oBpfnr-6dnEtg-m79GPr-FVFE9-eKdaHR-oi6UuW-einXy8-mKHUHk-5cFXGA-omswap-oV1kxp-oChdwV-oudGjB-9WFumT">Roger Soh/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>As with most Australian cities, Cairns has an urban layout based on wide streets, mostly with little or no greenery. <a href="https://www.melbournewater.com.au/community-and-education/help-protect-environment/raingardens">Rain gardens</a>, for instance, are rare. <a href="https://en.wikipedia.org/wiki/Bioswale">Bioswales</a> that slow and filter stormwater are present along highways, but seldom within the city. </p>
<p>The arguments for not adding greenery to the urban environment are familiar. These typically relate to costs of implementation and maintenance, but also to the speed with which water is taken out of streets during the tropical rainy season. This is because green stormwater solutions, if not well planned, can slow down the water flow, thus increasing floods.</p>
<p>However, cities can be designed in a way to <a href="https://theconversation.com/stormwater-innovations-mean-cities-dont-just-flush-rainwater-down-the-drain-40129">imitate nature</a> with solutions that are an integral part of the urban system. This can include dedicated areas of larger wetlands and parks, which capture water and filter pollution and undesired nutrients more efficiently, reducing polluted runoff to the reef.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/if-planners-understand-its-cool-to-green-cities-whats-stopping-them-55753">If planners understand it's cool to green cities, what's stopping them?</a>
</strong>
</em>
</p>
<hr>
<h2>Integrated urban design</h2>
<p>Integrated urban design is an aspect of city planning and design that could be further developed to ensure the whole system works more efficiently. This involves integrating the three elements that make up urban infrastructure: </p>
<ol>
<li><a href="https://theconversation.com/our-cities-need-more-trees-and-water-not-less-to-stay-liveable-22166">the green</a> – parks, residential gardens, rain gardens, green roofs and walls, bioswales, etc</li>
<li>the grey – built drains, footpaths, buildings, <a href="http://www.envacgroup.com/products/our_products/envac-stationary-vacuum-system">underground vacuum
system</a>, etc</li>
<li><a href="https://www.amazon.com/Blue-Urbanism-Exploring-Connections-Between/dp/1610914058">the blue</a> – streams, stormwater systems, etc.</li>
</ol>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/248338/original/file-20181203-194953-1cjc3uf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/248338/original/file-20181203-194953-1cjc3uf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/248338/original/file-20181203-194953-1cjc3uf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/248338/original/file-20181203-194953-1cjc3uf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/248338/original/file-20181203-194953-1cjc3uf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/248338/original/file-20181203-194953-1cjc3uf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/248338/original/file-20181203-194953-1cjc3uf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">A rain garden, which absorbs rain and stores water to help control run-off from impervious hard surfaces, in Wellington, New Zealand.</span>
<span class="attribution"><span class="source">Karine Dupré</span></span>
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<p>Urban infrastructure, therefore, can and should be planned and designed to provide <a href="https://link.springer.com/article/10.1007%2Fs11355-017-0346-6">multiple services</a>, including coastal resilience and healthier water streams and oceans. To achieve this, a neighbourhood or city-wide strategy needs to be implemented, instead of intermittent and ad hoc urban design solutions. Importantly, <a href="http://webpages.uidaho.edu/larc380/new380/assets/images/StormwaterFiles/images/HighPtSect.jpg">each element should coordinate with the others</a> to avoid overlaps, gaps and pitfalls. </p>
<p>This is what integrated urban design is about. So why don’t we implement it more often?</p>
<h2>Challenges and opportunities</h2>
<p><a href="https://www.sciencedirect.com/science/article/pii/S0013935117317115?via%3Dihub">Research has shown</a> that planning, designing and creating climate-resilient cities that are energy-optimised, revitalise urban landscapes and restore and support <a href="http://www.agriculture.gov.au/ag-farm-food/natural-resources/ecosystem-services">ecosystem services</a> is a major challenge at the planning scale. To generate an urban environment that promotes urban protection and resilience while minimising urbanisation impacts and restoring natural systems, we need to better anticipate the risks and have the means to take actions. In other words, it is a two-way system: well planned and designed green and blue infrastructures not only deliver better urbanised areas but will also protect the ocean from pollution. Additionally, it helps to manage future risks of severe weather. </p>
<p>The <a href="https://www.sciencedirect.com/science/article/pii/S1462901117305282?via%3Dihub">uncertainties of green infrastructure capacity and costs of maintenance, combined with inflexible finance schemes</a>, are obstacles to integrated urban solutions. Furthermore, the lack of <a href="https://www.tandfonline.com/doi/full/10.1080/01426397.2017.1353069">inter- and transdisciplinary approaches</a> results in <a href="http://www.arj.no/2012/03/12/disciplinarities-2/">disciplinary barriers</a> in research and policymaking to long-term planning of the sort that generates urban green infrastructure and its desired outcomes.</p>
<p>On the bright side, there is also strong evidence to suggest sound policy can <a href="http://sciencedirect.com/science/article/pii/S1618866716305027?via%3Dihub">help overcome these barriers</a> through technical guides based on scientific research, standards and financial incentives. </p>
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Read more:
<a href="https://theconversation.com/heres-how-green-infrastructure-can-easily-be-added-to-the-urban-planning-toolkit-57277">Here’s how green infrastructure can easily be added to the urban planning toolkit</a>
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<p><a href="https://linkinghub.elsevier.com/retrieve/pii/S1877343514001110">Collaborative partnerships</a> are promising, too. Partnerships between academia and industry tend to be more powerful than streamlined industry project developments. </p>
<p>Finally, and very promisingly, <a href="https://www.sciencedirect.com/science/article/pii/S0013935117316778?via%3Dihub">Australia has its own successful green infrastructure examples</a>. <a href="https://www.melbourne.vic.gov.au/community/parks-open-spaces/urban-forest/Pages/urban-forest-strategy.aspx">Melbourne’s urban forest strategy</a> has been <a href="https://www.sciencedirect.com/science/article/pii/S0013935117316778?via%3Dihub">internationally acclaimed</a>. Examples like these provide valuable insights into local green infrastructure governance. </p>
<p>Cairns has stepped up with some stunning blue <a href="http://www.qldbeaches.com/cairns-esplanade.html">infrastructure on the Esplanade</a> which raises awareness of both locals and visitors about the protection of our oceans. </p>
<p>This is only the start. Together academics, local authorities, industry stakeholders and communities can lead the way to resilient cities and healthier oceans.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/249195/original/file-20181206-128208-ixjv4.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/249195/original/file-20181206-128208-ixjv4.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/249195/original/file-20181206-128208-ixjv4.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=266&fit=crop&dpr=1 600w, https://images.theconversation.com/files/249195/original/file-20181206-128208-ixjv4.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=266&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/249195/original/file-20181206-128208-ixjv4.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=266&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/249195/original/file-20181206-128208-ixjv4.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=335&fit=crop&dpr=1 754w, https://images.theconversation.com/files/249195/original/file-20181206-128208-ixjv4.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=335&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/249195/original/file-20181206-128208-ixjv4.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=335&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Cairns Esplanade Lagoon helps raise awareness of the need to protect the ocean as the city grows.</span>
<span class="attribution"><span class="source">Karine Dupré</span>, <span class="license">Author provided</span></span>
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Read more:
<a href="https://theconversation.com/how-green-is-our-infrastructure-helping-cities-assess-its-value-for-long-term-liveability-50528">How green is our infrastructure? Helping cities assess its value for long-term liveability</a>
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<img src="https://counter.theconversation.com/content/107263/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Urbanisation is the main reason for rising temperatures and water pollution, but receives little attention in discussions about the health of water streams, reefs and oceans.Silvia Tavares, Lecturer in Urban Design, James Cook UniversityKarine Dupré, Associate Professor in Architecture, Griffith UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1069392018-11-18T18:53:49Z2018-11-18T18:53:49ZWhy predicting the weather and climate is even harder for Australia’s rainy northern neighbours<figure><img src="https://images.theconversation.com/files/245919/original/file-20181116-194500-1wx1jwa.jpg?ixlib=rb-1.1.0&rect=18%2C0%2C3059%2C2049&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Clouds roll across Samosir in northern Sumatra.</span> <span class="attribution"><span class="source">Shutterstock.com</span></span></figcaption></figure><p>Australians love to complain about weather forecasts, but compared with some other parts of the world ours are impressively accurate. Our large, mostly flat continent surrounded by oceans makes modelling Australia’s weather and climate relatively straightforward. </p>
<p>The same cannot be said about our neighbours to the north.</p>
<p>For Southeast Asian countries such as Indonesia and Papua New Guinea – which we collectively refer to as the “<a href="http://www.bom.gov.au/climate/about/tropics/maritime-continent.shtml">Maritime Continent</a>” – things are a lot more complicated. With their mountainous terrain and islands of different shapes and sizes, it’s much harder to model the weather and climate of this region.</p>
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Read more:
<a href="https://theconversation.com/the-tropics-are-getting-wetter-the-reason-could-be-clumpy-storms-39315">The tropics are getting wetter: the reason could be clumpy storms</a>
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<p>The models we use to make the most of our climate projections have to simulate the climate for many decades to provide us with useful information. To run such long simulations we have to compromise on resolution; even state-of-the-art global climate models divide the world into grid boxes more than 100km across. The Maritime Continent doesn’t come out too well at these resolutions.</p>
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<a href="https://images.theconversation.com/files/245511/original/file-20181114-194509-1bxaufj.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/245511/original/file-20181114-194509-1bxaufj.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/245511/original/file-20181114-194509-1bxaufj.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=424&fit=crop&dpr=1 600w, https://images.theconversation.com/files/245511/original/file-20181114-194509-1bxaufj.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=424&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/245511/original/file-20181114-194509-1bxaufj.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=424&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/245511/original/file-20181114-194509-1bxaufj.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=533&fit=crop&dpr=1 754w, https://images.theconversation.com/files/245511/original/file-20181114-194509-1bxaufj.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=533&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/245511/original/file-20181114-194509-1bxaufj.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=533&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">If you squint you can see it! The world’s surface looks a bit like a 1980s video game to a global climate model. The Maritime Continent region (in the black box) is especially messy.</span>
<span class="attribution"><span class="source">Author provided</span></span>
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<p>It’s unfortunate the Maritime Continent’s weather and climate are so tricky to simulate on long time scales. Due to its location right on the Equator and between the Indian and Pacific Oceans, this region has a defining influence on the global climate, being a major source of heat and water vapour to the atmosphere. If we don’t simulate the climate over the Maritime Continent well, we can get errors appearing on the global scale.</p>
<p>Besides that, the Maritime Continent is also home to hundreds of millions of people, and includes major cities such as Jakarta and Singapore. We need our weather and climate models to simulate the processes behind the <a href="https://www.aljazeera.com/news/2017/02/indonesia-widespread-flooding-hits-jakarta-170221104750422.html">severe storms</a>, <a href="https://www.straitstimes.com/asia/se-asia/more-falling-ill-in-malaysia-as-heatwave-takes-its-toll">heatwaves</a>, and <a href="https://www.abc.net.au/news/2018-09-20/drought-in-australia-spreading-to-indonesia/10249940">droughts</a> that these cities and the broader region experience. Accurate weather forecasts, seasonal outlooks and climate projections require models to simulate the atmosphere over the Maritime Continent well.</p>
<p>In our new study, <a href="https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2018GL080201">published in Geophysical Research Letters</a>, we show that many state-of-the-art global climate models struggle to simulate the climate of the Maritime Continent. But fortunately, a <a href="https://journals.ametsoc.org/doi/10.1175/JCLI-D-16-0688.1">higher-resolution model</a> captures more of the major processes in this area.</p>
<h2>The benefits of high resolution</h2>
<p>Like in Australia, much of the Maritime Continent region is wetter during La Niña seasons and drier in El Niño, although for some western coasts and Sumatra it’s the other way round. Many global climate models fail to reflect accurately this rainfall response to <a href="https://www.abc.net.au/news/2017-10-19/what-el-nino-la-nina-mean-australian-weather/9053464">El Niño and La Niña</a>.</p>
<p>We found that for climate models to do a good job in capturing the year-to-year variability in rainfall over the Maritime Continent, they need to do a few things well. Specifically, they need to represent accurately the amount of moisture held in the atmosphere, as well as the pattern of winds in the region. This gives the right pattern of rainfall response to El Niño and La Niña. </p>
<p>Our higher-resolution regional climate model does a much better job at simulating the Maritime Continent’s rainfall patterns than many of the global models we looked at. As the region has such a complex landscape, global models simply cannot capture enough detail on all the different processes between the land and the ocean, and the coasts and the mountains. But higher-resolution regional models can.</p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/5lzh30l_fPI?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">We can capture the processes behind rainfall in the Maritime Continent more realistically when we use a high-resolution model. In particular we can better represent the thunderstorms and heavy rain that tends to occur in the afternoons and evenings in the tropics.</span></figcaption>
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Read more:
<a href="https://theconversation.com/australia-moves-to-el-nino-alert-and-the-drought-is-likely-to-continue-104636">Australia moves to El Niño alert and the drought is likely to continue</a>
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<p>As the Maritime Continent is so important for the global climate but so difficult to model, there is a concerted effort to improve our models and to get more atmospheric observations across the region. </p>
<p>International projects such as the <a href="https://www.pmel.noaa.gov/ymc/">Years of the Maritime Continent</a> are taking place, with millions of dollars and dozens of researchers working on improving our understanding of the region’s weather and climate.</p>
<p>Ultimately, we hope that through better, higher-resolution model simulations, we can capture the processes behind the Maritime Continent’s weather and climate much more accurately. This should lead to better climate projections and seasonal forecasts not only for the region, but for the world as a whole.</p><img src="https://counter.theconversation.com/content/106939/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Andrew King receives funding from the Australian Research Council. </span></em></p><p class="fine-print"><em><span>Claire Vincent receives funding from the Australian Research Council. </span></em></p>Despite its global importance, the rainy ‘Maritime Continent’ around Indonesia is hard to capture using global climate models. But fear not - new research shows how to improve our forecasts.Andrew King, ARC DECRA fellow, The University of MelbourneClaire Vincent, Lecturer in Atmospheric Science, The University of MelbourneLicensed as Creative Commons – attribution, no derivatives.