tag:theconversation.com,2011:/us/topics/monsoon-4997/articlesMonsoon – The Conversation2023-10-24T15:12:04Ztag:theconversation.com,2011:article/2152022023-10-24T15:12:04Z2023-10-24T15:12:04ZHimalayan communities are under siege from landslides – and climate change is worsening the crisis<p>Three-quarters of annual rain in the Himalayas arrives in <a href="https://link.springer.com/chapter/10.1007/978-981-15-4327-2_11">the monsoon season</a> from June to September. Within this rainy period are sudden and extremely intense cloudbursts, which often “pop” over a relatively small area (akin to a cloud bursting open like a balloon). </p>
<p>As climate change is making these cloudbursts and other forms of heavy rainfall <a href="https://link.springer.com/chapter/10.1007/978-981-15-4327-2_8">more intense and more frequent</a> in the Himalayan foothills, the hilly slopes are becoming saturated more frequently, and thus unstable. Rainfall-triggered landslides are already happening extensively across the Himalayas, and things are likely to get worse. </p>
<p>From July to August 2023, the Indian Himalayas, particularly the state of Himachal Pradesh in the northern part of the country, experienced an unprecedented number of cloudbursts which triggered thousands of <a href="https://www.aljazeera.com/news/2023/8/14/dozens-dead-as-floods-landslides-hit-indias-himalayan-region">devastating landslides</a>. The state’s disaster management authority reported that by the end of August, heavy rain and rainfall-triggered landslides had caused <a href="https://www.thehindu.com/news/national/other-states/himachal-limps-back-to-normalcy-as-monsoon-withdraws-state-records-21-excess-rainfall/article67392435.ece">509 fatalities</a>, destroyed at least 2,200 homes and <a href="https://www.bbc.co.uk/news/world-asia-india-66615002">damaged a further 10,000</a>. It is estimated that Himachal Pradesh’s losses from this period amount to US$1.2 billion. Much of the destruction took place during two short periods, one in <a href="https://www.thestatesman.com/india/himachal-rains-death-toll-reaches-223-cm-monitoring-restoration-work-road-connectivity-1503210099.html">mid-July</a> and one in <a href="https://eos.org/thelandslideblog/the-14-august-2023-landslides-in-himachal-pradesh-india">mid-August</a>.</p>
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<span class="caption">A section of national highway (NH-03) is swept away by flash floods from cloudbursts in the Kullu district of Himachal Pradesh, July 2023.</span>
<span class="attribution"><span class="source">Ashutosh Kumar</span></span>
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<p>The level of damage to buildings, roads and bridges is extremely difficult to comprehend. Several sections of national and state roads have been washed away, a temple in Shimla collapsed and <a href="https://www.bbc.com/news/world-asia-india-66615002">killed 20 people</a>, rural dwellings largely constructed on sloped ground were washed away by rain, and houses are still sliding downhill. </p>
<p>Schools and hospitals have been damaged, posing an ongoing threat to lives. A school in Kullu district was closed for 52 days because the bridge which connected it to a town had been washed away. Local people have had no option but to live in tents with minimal facilities. They are hugely concerned about their safety ahead of a cold and snowy winter.</p>
<p>Four days of heavy rainfall in July 2023 triggered landslides that <a href="https://indianexpress.com/article/cities/shimla/himachal-counts-losses-31-dead-40-bridges-damaged-1300-roads-closed-8827396/">blocked around 1,300 roads</a> including five national highways, leaving the state almost cut off from the rest of India. This had huge knock-on effects as <a href="https://www.indiatoday.in/india/story/heavy-rain-north-india-weather-forecast-himachal-uttarakhand-jammu-landslides-punjab-delhi-haryana-flooded-2404715-2023-07-11">1,255 bus routes were suspended, 576 buses were stranded</a>, more than <a href="https://www.thestatesman.com/india/himachal-successfully-evacuated-70000-tourists-to-safety-cm-1503200900.html">70,000 tourists had to be evacuated</a>, and people could not access key facilities and services. This impeded emergency responders, causing critical delays in search and rescue operations as well as delivery of aid.</p>
<p>Across the whole of India, the summer monsoon and its related cloudbursts are <a href="https://agupubs.onlinelibrary.wiley.com/doi/10.1002/2014GL061573">decreasing</a>. But in the Himalayan foothills, they are <a href="https://rmets.onlinelibrary.wiley.com/doi/full/10.1002/joc.5560">increasing significantly</a> – partly because when warm moist air encounters the Himalayan barrier it rapidly lifts and cools, forming large clouds that then dump their rain. With intense rain happening more and more often in the Himalayan foothills, it is likely that 2023’s summer of disasters will occur again.</p>
<h2>Unnecessarily vulnerable</h2>
<p>Although climate change may be to blame for the rise in cloudbursts, in an ideal world rainfall alone needn’t lead to disastrous landslides. But the Himalayas have been made <a href="https://economictimes.indiatimes.com/news/how-to/what-are-cloudbursts-and-is-climate-change-making-them-more-frequent-in-india/articleshow/102229046.cms">more vulnerable</a> by human actions.</p>
<p>The region has largely been <a href="https://www.sciencedirect.com/science/article/pii/S0341816222006130?via%3Dihub">deforested</a>, removing tree roots which reinforce the ground and form a crucial barrier that stops soils washing away. And unplanned developments and haphazard construction have destabilised already fragile slopes.</p>
<p>Initial reports on this year’s landslides suggest the worst damages occurred along artificially cut slopes (for roads or buildings), where there has been a lack of proper provisioning for drainage and slope safety. In both India and Nepal, many of the hill roads have been <a href="https://www.lyellcollection.org/doi/10.1144/qjegh2016-109">haphazardly constructed</a>, which makes landslides during rainfall <a href="https://www.sciencedirect.com/science/article/pii/S0013795222002721">more likely</a>. Construction guidelines and building codes are <a href="https://www.sciencedirect.com/science/article/pii/S0013795222002563">outdated</a> and have been ignored anyway, and there is little assessment of the link between urbanisation and landslide risk. </p>
<p>One obvious solution is to prevent rain from penetrating the ground, so the slopes avoid losing any strength. However, if the soil is entirely prevented from absorbing any rain, the water will instead run off the surface and cause greater flooding problems further downhill.</p>
<p>One engineering solution is to place an artificial soil layer above the natural soil to temporarily hold water in the surface when it is raining extremely hard, preventing it penetrating deeper within the slope. This “<a href="https://ascelibrary.org/doi/10.1061/9780784484968.013">climate adaptive barrier layer</a>” will then release water back to the atmosphere during a later drying period. </p>
<p>As the heavy rain intensifies, it will be hugely important for the Himalayas to implement new user-friendly and reliable construction guidelines that factor in how the climate is changing. Landslides can’t be avoided entirely, and India certainly won’t be able to reverse global warming and the increase in cloudbursts any time soon. But these preventive actions should at least make communities more resilient to the changing climate.</p>
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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>Haphazard construction has made the region more vulnerable to increasingly intense rainfall.Ashutosh Kumar, Assistant Professor, School of Civil & Environmental Engineering, Indian Institute of Technology MandiEedy Sana, PhD Candidate, Geotechnical Engineering, Indian Institute of Technology MandiEllen Beatrice Robson, Postdoctoral research associate, Durham UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2079022023-06-21T12:30:01Z2023-06-21T12:30:01ZOcean heat is off the charts – here’s what that means for humans and ecosystems around the world<figure><img src="https://images.theconversation.com/files/532300/original/file-20230615-15-tk80ew.png?ixlib=rb-1.1.0&rect=717%2C150%2C1160%2C710&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The Indian Ocean's heat is having effects on land, too.</span> <span class="attribution"><a class="source" href="https://coralreefwatch.noaa.gov/product/5km/index_5km_sst.php">NOAA Coral Reef Watch</a></span></figcaption></figure><p>Ocean temperatures have been <a href="https://climatereanalyzer.org/clim/sst_daily/">off the charts since mid-March 2023</a>, with the highest average levels in 40 years of satellite monitoring, and the impact is breaking through in disruptive ways around the world.</p>
<p>The sea of Japan is <a href="https://www.energyconnects.com/news/renewables/2023/may/early-heat-wave-gives-tokyo-a-glimpse-of-a-sweltering-summer/">more than 7 degrees</a> Fahrenheit (4 degrees Celsius) warmer than average. The Indian monsoon, closely tied to conditions in the warm Indian Ocean, has been <a href="https://mausam.imd.gov.in/responsive/rainfallinformation.php">well below its expected strength</a>.</p>
<p>Spain, France, England and the whole Scandinavian Peninsula <a href="https://joint-research-centre.ec.europa.eu/jrc-news-and-updates/severe-drought-western-mediterranean-faces-low-river-flows-and-crop-yields-earlier-ever-2023-06-13_en">are also seeing rainfall far below normal</a>, likely connected to an extraordinary marine heat wave in the eastern North Atlantic. Sea surface temperatures there have been 1.8 to 5 F (1 to 3 C) above average from the coast of Africa all the way to Iceland.</p>
<p>So, what’s going on?</p>
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<a href="https://images.theconversation.com/files/533018/original/file-20230620-27-zj3g9.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Chart shows 22 years of sea surface temperature, with 2023 well above that of previous years" src="https://images.theconversation.com/files/533018/original/file-20230620-27-zj3g9.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/533018/original/file-20230620-27-zj3g9.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=382&fit=crop&dpr=1 600w, https://images.theconversation.com/files/533018/original/file-20230620-27-zj3g9.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=382&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/533018/original/file-20230620-27-zj3g9.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=382&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/533018/original/file-20230620-27-zj3g9.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=480&fit=crop&dpr=1 754w, https://images.theconversation.com/files/533018/original/file-20230620-27-zj3g9.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=480&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/533018/original/file-20230620-27-zj3g9.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=480&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">Sea surface temperatures are running well above the average since satellite monitoring began. The thick black line is 2023. The orange line is 2022. The 1982-2011 average is the middle dashed line.</span>
<span class="attribution"><a class="source" href="https://climatereanalyzer.org/clim/sst_daily/">ClimateReanalyzer.org/NOAA OISST v2.1</a></span>
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<p>El Niño is partly to blame. <a href="https://theconversation.com/el-nino-is-back-thats-good-news-or-bad-news-depending-on-where-you-live-205974">This climate phenomenon</a>, now developing in the equatorial Pacific Ocean, is characterized by warm waters in the central and eastern Pacific, which generally weakens the trade winds in the tropics. This weakening of those winds can affect oceans and land around the world.</p>
<p>But there are other forces at work on ocean temperatures.</p>
<p>Underlying everything is global warming – the <a href="https://climate.nasa.gov/">continuing rising trend</a> of <a href="https://images.theconversation.com/files/533088/original/file-20230621-16119-v4sxij.png">sea surface and land temperatures</a> for the past several decades as human activities have increased greenhouse gas concentrations in the atmosphere.</p>
<p>The world just came off <a href="https://earthobservatory.nasa.gov/images/150691/la-nina-times-three" title=""">three straight years</a> of La Niña – El Niño’s opposite, characterized by cooler waters rising in the equatorial Pacific. La Niña has a <a href="https://oceanservice.noaa.gov/facts/ninonina.html">cooling effect</a> globally that helps keep global sea surface temperatures in check but can also mask global warming. With that cooling effect turned off, the heat is increasingly evident.</p>
<p>Arctic sea ice was also <a href="https://nsidc.org/arcticseaicenews/">unusually low</a> in May and early June, and it may play a role. Losing ice cover <a href="https://oceanservice.noaa.gov/facts/sea-ice-climate.html">can increase water temperatures</a>, because dark open water absorbs solar radiation that white ice had reflected back into space.</p>
<p>These influences are playing out in various ways around the world. </p>
<h2>The effects of extraordinary Atlantic heat</h2>
<p>In early June 2023, <a href="https://scholar.google.com/citations?user=6jEKlrQAAAAJ&hl=en">I visited</a> the <a href="https://www.norceresearch.no/en">NORCE climate center</a> in Bergen, Norway, for two weeks to meet with other ocean scientists. The warm waters and mild winds across the eastern North Atlantic brought a long stretch of sunny, warm weather in a month when more than 70% of days normally would have been downpours. </p>
<p>The whole agricultural sector of Norway is now bracing for a drought as bad as the one in 2018, when <a href="https://bg.copernicus.org/articles/17/1655/2020/">yield was 40% below normal</a>. Our train from Bergen to Oslo had a two-hour delay because the brakes of one car overheated and the 90 F (32 C) temperatures approaching the capital were too high to allow them to cool down. </p>
<p>Many scientists have speculated on the causes of the eastern North Atlantic’s unusually high temperatures, and several studies are underway.</p>
<p>Weakened winds caused the <a href="https://www.weatheronline.co.uk/reports/wxfacts/The-Azores-High.htm">Azores high</a>, a semi-permanent high pressure system over the Atlantic that affects Europe’s weather, to be especially weak and brought less <a href="https://atmosphere.copernicus.eu/what-saharan-dust-and-how-does-it-change-atmosphere-and-air-we-breathe">dust from the Sahara</a> over the ocean during the spring, which may have increased the amount of solar radiation reaching the water. A decrease in human-produced aerosol emissions in Europe and in the United States over the past few years – which has succeeded in improving air quality – <a href="https://doi.org/10.1002/2017GL076079">may also have reduced the cooling effect</a> such aerosols have.</p>
<h2>A weakened monsoon in South Asia</h2>
<p>In the Indian Ocean, El Niño tends to cause a warming of the water in April and May that <a href="https://www.climate.gov/news-features/blogs/enso/enso-and-indian-monsoon%E2%80%A6-not-straightforward-you%E2%80%99d-think">can dampen the crucial Indian monsoon</a>.</p>
<p>That may be happening – the monsoon <a href="https://www.reuters.com/world/india/indias-stalled-monsoon-gain-momentum-3-4-days-weather-officials-2023-06-20/">was much weaker than normal</a> from mid-May to mid-June 2023. That can be a problem for a large part of South Asia, where most of the agriculture is still rain-fed and depends heavily on the summer monsoon.</p>
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<img alt="Three adults walk under umbrellas sheltering them from the sun. A woman without an umbrella shades her eyes with her hands on a hot day, and a boy wears a cap." src="https://images.theconversation.com/files/532987/original/file-20230620-19276-e74oss.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/532987/original/file-20230620-19276-e74oss.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=387&fit=crop&dpr=1 600w, https://images.theconversation.com/files/532987/original/file-20230620-19276-e74oss.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=387&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/532987/original/file-20230620-19276-e74oss.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=387&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/532987/original/file-20230620-19276-e74oss.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=487&fit=crop&dpr=1 754w, https://images.theconversation.com/files/532987/original/file-20230620-19276-e74oss.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=487&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/532987/original/file-20230620-19276-e74oss.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=487&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">India saw sweltering temperatures in May and June 2023.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/people-out-at-india-gate-on-hot-afternoon-on-may-21-2023-in-news-photo/1256969460">Sanjeev Verma/Hindustan Times via Getty Images</a></span>
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<p>The Indian Ocean also saw an intense, <a href="https://www.reuters.com/graphics/ASIA-WEATHER/byvrlywymve/index.html">slow-moving cyclone</a> in the Arabian Sea this year that deprived land of moisture and rainfall for weeks. Studies suggest storms can sit for <a href="https://theconversation.com/what-makes-hurricanes-stall-and-why-is-that-so-hard-to-forecast-146804">longer over warmer waters</a>, gaining strength and pulling moisture to their core, and that can deprive surrounding land masses of water, increasing the risk of droughts, wildfires and marine heat waves.</p>
<h2>North American hurricane season up in the air</h2>
<p>In the Atlantic, the weakening trade winds with El Niño tend to <a href="https://theconversation.com/atlantic-hurricane-season-2023-el-nino-and-extreme-atlantic-ocean-heat-are-about-to-clash-204670">tamp down hurricane activity</a>, but warm Atlantic temperatures can supercharge those storms. Whether the ocean heat, if it persists into fall, will override El Niño’s effects remains to be seen.</p>
<p><iframe id="hzENA" class="tc-infographic-datawrapper" src="https://datawrapper.dwcdn.net/hzENA/4/" height="400px" width="100%" style="border: none" frameborder="0"></iframe></p>
<h2>Risk of marine heat waves in South America</h2>
<p><a href="https://theconversation.com/el-nino-is-coming-and-ocean-temps-are-already-at-record-highs-that-can-spell-disaster-for-fish-and-corals-202424">Marine heat waves</a> can also have huge impacts on marine ecosystems, <a href="https://theconversation.com/coral-reefs-are-dying-as-climate-change-decimates-ocean-ecosystems-vital-to-fish-and-humans-164743">bleaching coral reefs</a> and causing the death or movement of entire species. Coral-based ecosystems are nurseries for fish that provide food for 1 billion people around the world.</p>
<p>The reefs of the Galapagos Islands and those along the coastlines of Colombia, Panama and Ecuador are already at risk of <a href="https://coralreefwatch.noaa.gov/">severe bleaching and mortality from this year’s El Nino</a>. Meanwhile, the Japan Sea and the eastern Mediterranean Sea are both losing their biodiversity to invasive species – <a href="https://doi.org/10.1007/s10750-014-2046-7">giant jellyfish in Asia</a> and <a href="https://doi.org/10.12681/mms.21845">lionfish in the Mediterranean</a> – that can thrive in warmer waters.</p>
<h2>These kinds of risks are increasing</h2>
<p>Spring 2023 was exceptional, with several chaotic weather events accompanying the formation of El Niño and the exceptionally warmer temperatures in many parts of the world. At the same time, the warming of the oceans and atmosphere increase the chances for this kind of ocean warming.</p>
<p>To lower the risk, the world needs to reduce baseline warming by limiting excess greenhouse gas emissions, like fossil fuels, and <a href="https://www.ipcc.ch/report/ar6/syr/">move to a carbon-neutral planet</a>. People will have to <a href="https://www.un.org/en/climatechange/climate-adaptation">adapt to a warming climate</a> in which extreme events are more likely and learn how to mitigate their impact.</p><img src="https://counter.theconversation.com/content/207902/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Annalisa Bracco receives funding from NSF, NOAA, DOE. </span></em></p>Drought in Europe, dwindling Arctic sea ice, a slow start to the Indian monsoon – unusually hot ocean temperatures can disrupt climate patterns around the world, as an ocean scientist explains.Annalisa Bracco, Professor of Ocean and Climate Dynamics, Georgia Institute of TechnologyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1983502023-02-01T06:12:08Z2023-02-01T06:12:08ZSeychelles is becoming overwhelmed by marine plastic – we now know where it comes from<figure><img src="https://images.theconversation.com/files/507320/original/file-20230131-12-y5egtu.jpg?ixlib=rb-1.1.0&rect=15%2C0%2C5087%2C3396&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A green turtle on Aldabra entangled in abandoned fishing gear.</span> <span class="attribution"><span class="source">Rich Baxter</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span></figcaption></figure><p>More than 1,000km southwest of Mahé, the main inhabited island in Seychelles, lies a ring of coral islands called the <a href="https://en.wikipedia.org/wiki/Aldabra">Aldabra Atoll</a>. The islands are a <a href="https://whc.unesco.org/en/list/185/">Unesco world heritage site</a> and support a huge diversity of marine species including manta rays and tiger sharks. The atoll is also a <a href="https://theconversation.com/how-we-discovered-that-sea-turtles-in-seychelles-have-recovered-from-the-brink-179041">breeding site</a> for endangered <a href="https://www.worldwildlife.org/species/green-turtle">green turtles</a>.</p>
<p>Aldabra has long been <a href="http://www.sif.sc/aldabra">protected</a> from threats to its biodiversity by its remoteness. But now plastic debris is strewn across Aldabra’s coastlines, threatening nearby marine ecosystems. <a href="https://doi.org/10.1126/science.aar3320">Research</a> finds the likelihood of coral disease increases from 4% to 89% when coral are in contact with plastic.</p>
<p>The <a href="http://sif.sc/">Seychelles Islands Foundation</a>, who are responsible for managing Aldabra, conducted a plastic clean-up operation in partnership with <a href="https://www.ox.ac.uk/news/2020-09-10-millions-dollars-clean-tuna-nets-and-flip-flops-island-state">Oxford University</a> in 2019. Roughly 25 tonnes of plastic waste were removed from the islands. </p>
<p>A <a href="https://doi.org/10.1016/j.marpolbul.2022.114497">new study</a> that we co-authored modelled the flow of plastic debris in the Indian Ocean between 1993 and 2019 and traced it to its source. We found that none of the plastic that washes up on Aldabra comes from the islands themselves. </p>
<figure class="align-center ">
<img alt="An aerial shot of the Aldabra Atoll." src="https://images.theconversation.com/files/507332/original/file-20230131-7253-8kr9t0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/507332/original/file-20230131-7253-8kr9t0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=596&fit=crop&dpr=1 600w, https://images.theconversation.com/files/507332/original/file-20230131-7253-8kr9t0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=596&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/507332/original/file-20230131-7253-8kr9t0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=596&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/507332/original/file-20230131-7253-8kr9t0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=749&fit=crop&dpr=1 754w, https://images.theconversation.com/files/507332/original/file-20230131-7253-8kr9t0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=749&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/507332/original/file-20230131-7253-8kr9t0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=749&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The Aldabra Atoll, part of the Seychelles’ Outer Islands.</span>
<span class="attribution"><span class="source">Seychelles Islands Foundation</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<h2>Simulating plastic flow</h2>
<p>Using data on plastic waste generation and fishing activity, we generated hundreds of billions of virtual plastic particles entering the Indian ocean. We then simulated their movement based on ocean currents, waves and winds.</p>
<p>Bottle caps and other low-buoyancy items sink fast and plastic loses buoyancy as it fragments or becomes <a href="https://www.sciencedirect.com/science/article/pii/S0269749116300264">covered in waterborne organisms</a>. Items that remain buoyant for longer are transported further distances. To reach Aldabra from the eastern Indian Ocean, our model estimates that debris must be floating for at least six months.</p>
<p>We determined the likelihood that this debris would wash up on the coast by analysing the rate at which <a href="https://www.aoml.noaa.gov/phod/gdp/index.php">scientific “drifters”</a> (instruments that record ocean currents) and <a href="https://www.sciencedirect.com/science/article/pii/S0006320720309976">GPS-tracked floating fishing devices</a> become “beached”. Free-floating instruments such as these behave well as proxies for floating plastic. These observations indicate that around 3% of the debris that is within 10km of a coast beaches each day.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/ma0wlFfA6dI?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Four-year simulation of highly buoyant marine debris transport in the Indian Ocean.</span></figcaption>
</figure>
<h2>Island under siege</h2>
<p>Our model predicts that Indonesia is responsible for most of the plastic debris, including as flip-flops and plastic packaging, that beaches across Seychelles. Various other countries including India, Sri Lanka and the Philippines are also major sources.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/506216/original/file-20230125-11-441nau.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A figure showing the sources of marine debris across the Indian Ocean." src="https://images.theconversation.com/files/506216/original/file-20230125-11-441nau.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/506216/original/file-20230125-11-441nau.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=770&fit=crop&dpr=1 600w, https://images.theconversation.com/files/506216/original/file-20230125-11-441nau.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=770&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/506216/original/file-20230125-11-441nau.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=770&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/506216/original/file-20230125-11-441nau.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=968&fit=crop&dpr=1 754w, https://images.theconversation.com/files/506216/original/file-20230125-11-441nau.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=968&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/506216/original/file-20230125-11-441nau.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=968&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Sources of marine debris for Seychelles and other remote islands in the western Indian Ocean (1993-2014).</span>
<span class="attribution"><a class="source" href="https://creativecommons.org/licenses/by/4.0/">Vogt-Vincent et al. (2023)</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>But Seychelles is also contaminated with plastic waste from other places. </p>
<p>Almost half of the plastic bottles found on Aldabra during the initial clean-up had been manufactured in China. But ocean currents do not flow directly between China and the western Indian Ocean. It is thus unlikely that a large number of bottles could float from China to Seychelles. </p>
<p>But Seychelles is close to a <a href="https://www.marinetraffic.com/en/ais/home/centerx:63.4/centery:-8.7/zoom:4">major shipping lane</a> that connects southeast Asia to the Atlantic. If bottles were discarded from ships crossing the Indian Ocean then they would likely beach across Seychelles. </p>
<p><a href="https://doi.org/10.1038/s41598-020-71444-6">Research</a> that we conducted in 2020 estimated that the fishing industry was responsible for 83% of the plastic waste on Aldabra. Most of the fishing gear abandoned by <a href="https://www.msc.org/what-we-are-doing/our-approach/fishing-methods-and-gear-types/purse-seine">“purse seine” fisheries</a> (a method of fishing that employs large nets to catch tuna) likely relates to regional fishing activity around Seychelles. But abandoned gear from longline fisheries may have drifted in from as far afield as western Australia.</p>
<p>Perhaps most importantly, our modelling also suggests that the rates at which plastic debris will beach in the Indian Ocean will follow strong seasonal cycles. </p>
<p>Winds tend to have a <a href="https://iridl.ldeo.columbia.edu/maproom/Global/Climatologies/Vector_Winds.html?bbox=bb%3A15.12%3A-39.110%3A132.52%3A35.656%3Abb&T=Jul">southerly (northward) component</a> during the Indian Ocean’s summer monsoon season. But major debris sources such as Indonesia and India share similar, or more northerly, latitudes with Seychelles. During this period, debris from these sources tends to miss Seychelles and is transported further north. </p>
<p>By contrast, the winds reverse during the <a href="https://iridl.ldeo.columbia.edu/maproom/Global/Climatologies/Vector_Winds.html?bbox=bb%3A15.12%3A-39.110%3A132.52%3A35.656%3Abb&T=Jan">winter monsoons</a> and transport debris directly towards Seychelles. We expect plastic debris accumulation to peak in Seychelles shortly after the winter monsoons (February to April). In the southernmost islands, almost all of the debris that beaches will do so at this point. </p>
<figure class="align-center ">
<img alt="A map showing the direction of ocean currents in the Indian Ocean across different seasons." src="https://images.theconversation.com/files/506218/original/file-20230125-12-c6pgwb.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/506218/original/file-20230125-12-c6pgwb.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=392&fit=crop&dpr=1 600w, https://images.theconversation.com/files/506218/original/file-20230125-12-c6pgwb.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=392&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/506218/original/file-20230125-12-c6pgwb.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=392&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/506218/original/file-20230125-12-c6pgwb.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=493&fit=crop&dpr=1 754w, https://images.theconversation.com/files/506218/original/file-20230125-12-c6pgwb.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=493&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/506218/original/file-20230125-12-c6pgwb.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=493&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Schematic of ocean currents in the Indian Ocean.</span>
<span class="attribution"><a class="source" href="https://creativecommons.org/licenses/by/4.0/">Vogt-Vincent et al. (2023)</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<h2>Planning effective mitigation</h2>
<p>Seychelles is not responsible for generating this waste but face mounting environmental and economic costs. For example, <a href="https://doi.org/10.1038/s41598-020-71444-6">500 tonnes</a> of litter remained following the initial clean-up of Aldabra’s coasts, which may cost up to US$5 million (£4 million) to remove.</p>
<p>The United Nations last year <a href="https://www.unep.org/news-and-stories/story/what-you-need-know-about-plastic-pollution-resolution">agreed</a> to establish a <a href="https://www.plasticstreaty.org/">global plastic treaty</a> that will tackle plastic pollution at its roots. But negotiations only began recently and it may be a long time before the treaty has any meaningful impact. </p>
<figure class="align-center ">
<img alt="An aerial shot of a group of people removing litter from a beach." src="https://images.theconversation.com/files/506404/original/file-20230125-22-6nbe1u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/506404/original/file-20230125-22-6nbe1u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/506404/original/file-20230125-22-6nbe1u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/506404/original/file-20230125-22-6nbe1u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/506404/original/file-20230125-22-6nbe1u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/506404/original/file-20230125-22-6nbe1u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/506404/original/file-20230125-22-6nbe1u.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">A team from the Seychelles Islands Foundation removing litter from the coastline of Aldabra.</span>
<span class="attribution"><span class="source">Seychelles islands Foundation</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>Until then our modelling may help to establish other strategies to reduce the accumulation of plastic debris in Seychelles. </p>
<p>We identified fishing gear and shipping as being responsible for the majority of plastic pollution on Seychelles. Better enforcement of existing laws such as the 1983 ban on the disposal of plastic into the sea under the <a href="https://www.imo.org/en/about/Conventions/Pages/International-Convention-for-the-Prevention-of-Pollution-from-Ships-(MARPOL).aspx">Marpol Convention</a> should reduce the amount of plastic entering the Indian Ocean.</p>
<p>Predicting the peak of plastic accumulation in Seychelles will also maximise the effectiveness of beach clean-ups. Removing litter shortly after its arrival will minimise the time debris spends being broken down into unmanageable fragments.</p>
<p>Remote Indian Ocean islands are increasingly affected by plastic waste generated overseas. But by modelling the flow of plastic debris, we now have the chance to develop more effective strategies to reduce plastic accumulation and strengthen demands for stronger commitments under the global plastic treaty. </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>
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<p class="fine-print"><em><span>Noam Vogt-Vincent receives funding from the Natural Environment Research Council (NERC). </span></em></p><p class="fine-print"><em><span>April Burt works with Seychelles Islands Foundation, who manage Aldabra Atoll</span></em></p>Remote islands in the Indian Ocean are now strewn with plastic waste – the origin of this waste has until now not been established.Noam Vogt-Vincent, DPhil Candidate in Earth Sciences, University of OxfordApril Burt, Research Associate, University of OxfordLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1892222022-09-19T19:12:19Z2022-09-19T19:12:19Z1,000-year-old stalagmites from a cave in India show the monsoon isn’t so reliable – their rings reveal a history of long, deadly droughts<figure><img src="https://images.theconversation.com/files/482572/original/file-20220902-17-s9as81.JPG?ixlib=rb-1.1.0&rect=510%2C11%2C3338%2C2215&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Stalagmites grow from the cave floor up as water drips down.</span> <span class="attribution"><span class="source">Gayatri Kathayat</span></span></figcaption></figure><p>In a remote cave in northeast India, rainwater has slowly dripped from the ceiling in the same spots for over 1,000 years. With each drop, minerals in the water accumulate on the floor below, slowly growing into calcium carbonate towers known as <a href="https://earthobservatory.nasa.gov/features/Paleoclimatology_Speleothems">stalagmites</a>.</p>
<p>These stalagmites are more than geological wonders – like tree rings, their layers record the region’s rainfall history. They also carry a warning about the potential for catastrophic multiyear droughts in the future. </p>
<p>By analyzing the geochemistry of these stalagmites in a <a href="https://www.pnas.org/">new study</a> published Sept. 19, 2022, in the Proceedings of the National Academy of Sciences, we were able to create the most precise chronology yet of the summer Indian monsoon over the past millennium. It documents how the Indian subcontinent frequently experienced long, severe droughts unlike any observed in the last 150 years of reliable <a href="https://mol.tropmet.res.in/monsoon-interannual-timeseries/">monsoon rainfall</a> measurements. </p>
<p>The drought periods we detected are in striking synchrony with <a href="https://famineanddearth.exeter.ac.uk/index.html">historical accounts of droughts, famines</a>, <a href="https://www.indianculture.gov.in/rarebooks/history-and-economics-indian-famines">mass mortality events</a> and <a href="https://doi.org/10.1016/j.eeh.2007.11.002">geopolitical changes in the region</a>.</p>
<p>They show how the decline of the Mughal Empire and India’s textile industries in the 1780s and 1790s coincided with the most severe 30-year period of drought over the millennium. The depth and duration of the drought would have caused widespread crop failures and the level of famine <a href="http://sro.sussex.ac.uk/id/eprint/83046/3/final1780srevised1.pdf">discussed in written documents</a> at the time. </p>
<p>Another long drought encompasses the 1630-1632 Deccan famine, one of the most devastating droughts in India’s history. Millions of people died as crops failed. Around the same time, the elaborate Mughal capital of <a href="https://www.jstor.org/stable/41372237">Fatehpur Sikri was abandoned</a> and the <a href="https://doi.org/10.1126/sciadv.1701296">Guge Kingdom collapsed</a> in western Tibet.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/482563/original/file-20220902-13436-lqzj39.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/482563/original/file-20220902-13436-lqzj39.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=518&fit=crop&dpr=1 600w, https://images.theconversation.com/files/482563/original/file-20220902-13436-lqzj39.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=518&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/482563/original/file-20220902-13436-lqzj39.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=518&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/482563/original/file-20220902-13436-lqzj39.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=651&fit=crop&dpr=1 754w, https://images.theconversation.com/files/482563/original/file-20220902-13436-lqzj39.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=651&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/482563/original/file-20220902-13436-lqzj39.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=651&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Buland Darwaza (Door of Victory) at Fatehpur Sikri, India.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Fatehput_Sikiri_Buland_Darwaza_gate_2010.jpg">Marcin Białek via Wikimedia</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-sa/4.0/">CC BY-NC-SA</a></span>
</figcaption>
</figure>
<p>Our findings have important implications today for water planning in a warming world, particularly for India, which, with its vast monsoon-reliant agriculture industry, is on pace to <a href="https://www.un.org/development/desa/pd/sites/www.un.org.development.desa.pd/files/wpp2022_summary_of_results.pdf">soon be the most populous</a> country on the planet.</p>
<h2>Why the monsoon’s history matters</h2>
<p>Scientists began systematically measuring India’s monsoon rainfall with instruments around the 1870s. Since then, India has experienced about 27 regionally widespread droughts. Among them, only one – 1985 to 1987 – was a three-year consecutive drought or worse.</p>
<p><iframe id="7DqHs" class="tc-infographic-datawrapper" src="https://datawrapper.dwcdn.net/7DqHs/2/" height="400px" width="100%" style="border: none" frameborder="0"></iframe></p>
<p>The apparent stability of the Indian monsoon in that data might lead one to surmise that neither protracted droughts lasting multiple years nor frequent droughts are intrinsic aspects of its variability. This seemingly reassuring view currently informs the region’s present-day water resource infrastructure.</p>
<p>However, the stalagmite evidence of prolonged, severe droughts over the past 1,000 years paints a different picture.</p>
<p>It indicates that the short instrumental period does not capture the full range of Indian monsoon variability. It also raises questions about the region’s current water resources, sustainability and mitigation policies that discount the possibility of protracted droughts in the future.</p>
<figure class="align-center ">
<img alt="Line chart through time showing drought years and rainy years, with several periods of extreme drought." src="https://images.theconversation.com/files/482443/original/file-20220902-24-7ko4kb.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/482443/original/file-20220902-24-7ko4kb.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=388&fit=crop&dpr=1 600w, https://images.theconversation.com/files/482443/original/file-20220902-24-7ko4kb.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=388&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/482443/original/file-20220902-24-7ko4kb.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=388&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/482443/original/file-20220902-24-7ko4kb.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=488&fit=crop&dpr=1 754w, https://images.theconversation.com/files/482443/original/file-20220902-24-7ko4kb.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=488&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/482443/original/file-20220902-24-7ko4kb.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=488&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Timeline of major societal and geopolitical changes in India and the oxygen isotope record from Mawmluh cave.</span>
<span class="attribution"><a class="source" href="https://doi.org/10.1073/pnas.2207487119">Gayatri Kathayat</a></span>
</figcaption>
</figure>
<h2>How do stalagmites capture a region’s monsoon history?</h2>
<p>To reconstruct past variations in rainfall, we analyzed stalagmites from Mawmluh cave, near the town of Cherrapunji in the state of Meghalaya – <a href="https://blog.thomascook.in/cherrapunji-the-wettest-place-on-earth">one of the wettest locations in the world</a>.</p>
<p>Stalagmites are conelike structures that grow slowly from the ground up, typically at a rate of about one millimeter every 10 years. Trapped within their growth layers are minute amounts of uranium and other elements that were acquired as rainwater infiltrated the rocks and soil above the cave. Over time, uranium trapped in stalagmites decays into thorium at a predictable pace, so we can figure out the age of each stalagmite growth layer by <a href="https://doi.org/10.1016/B978-0-12-814124-3.00128-X">measuring the ratio of uranium to thorium</a>.</p>
<p>The oxygen in rainwater molecules comes in two primary types of isotopes – heavy and light. As stalagmites grow, they lock into their structure the oxygen isotope ratios of the percolating rainwater that seeps into the cave. Subtle variations in this ratio can arise from a range of climatic conditions at the time the rainwater originally fell.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/482573/original/file-20220902-26-qic1wi.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A photo from inside a cave, with red ribbons tied around two different stalagmites." src="https://images.theconversation.com/files/482573/original/file-20220902-26-qic1wi.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/482573/original/file-20220902-26-qic1wi.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/482573/original/file-20220902-26-qic1wi.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/482573/original/file-20220902-26-qic1wi.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/482573/original/file-20220902-26-qic1wi.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/482573/original/file-20220902-26-qic1wi.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/482573/original/file-20220902-26-qic1wi.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">Stalagmite formation are marked inside Mawmluh Cave, where the new study was based.</span>
<span class="attribution"><span class="source">Gayatri Kathayat</span></span>
</figcaption>
</figure>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/482575/original/file-20220902-20-4ueeds.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="The interior of a stalagmite when sliced vertically shows its growth rings." src="https://images.theconversation.com/files/482575/original/file-20220902-20-4ueeds.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/482575/original/file-20220902-20-4ueeds.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=294&fit=crop&dpr=1 600w, https://images.theconversation.com/files/482575/original/file-20220902-20-4ueeds.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=294&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/482575/original/file-20220902-20-4ueeds.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=294&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/482575/original/file-20220902-20-4ueeds.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=369&fit=crop&dpr=1 754w, https://images.theconversation.com/files/482575/original/file-20220902-20-4ueeds.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=369&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/482575/original/file-20220902-20-4ueeds.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=369&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 cross-section of a stalagmite shows differences in its ring formation as climate conditions changed.</span>
<span class="attribution"><span class="source">Gayatri Kathayat</span></span>
</figcaption>
</figure>
<p>Our <a href="https://doi.org/10.1038/s43247-021-00165-z">previous research in this area showed</a> that variations in oxygen isotope ratios in rainwater, and consequently, in stalagmites, track changes in the relative abundance of different moisture sources that contribute to summer monsoon rainfall.</p>
<p>During years when monsoon circulation is weak, rainfall here is primarily derived from the moisture that evaporated from the nearby Arabian Sea. During strong monsoon years, however, atmospheric circulation brings copious amounts of moisture to this area all the way from the southern Indian Ocean.</p>
<p>The two moisture sources have quite different oxygen isotope signatures, and this ratio is faithfully preserved in the stalagmites. We can use this clue to learn about the overall strength of the monsoon intensity at the time the stalagmite formed. We pieced together the <a href="https://doi.org/10.1073/pnas.2207487119">monsoon rainfall history</a> by extracting minute amounts of calcium carbonate from its growth rings and then measuring the oxygen isotope ratios. To anchor our climate record to precise calendar years, we measured the uranium and thorium ratio.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/482574/original/file-20220902-20-5e2ea0.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A group of stalagmite cones rise from the cave floor in a dramatic image" src="https://images.theconversation.com/files/482574/original/file-20220902-20-5e2ea0.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/482574/original/file-20220902-20-5e2ea0.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/482574/original/file-20220902-20-5e2ea0.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/482574/original/file-20220902-20-5e2ea0.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/482574/original/file-20220902-20-5e2ea0.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/482574/original/file-20220902-20-5e2ea0.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/482574/original/file-20220902-20-5e2ea0.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">Stalagmites grow from the ground, and stalactites grow from above. These are in Mawmluh Cave, where the authors conducted their research.</span>
<span class="attribution"><span class="source">Gayatri Kathayat</span></span>
</figcaption>
</figure>
<h2>Next steps</h2>
<p>The paleoclimate records can usually tell what, where and when something happened. But often, they alone cannot answer why or how something happened. </p>
<p>Our new study shows that protracted droughts frequently occurred during the past millennia, but we do not have a good understanding of why the monsoon failed in those years. Similar studies using Himalayan ice cores, tree rings and other caves have also detected protracted droughts but face the same challenge. </p>
<p>In the next phase of our study, we are teaming up with climate modelers to conduct coordinated proxy-modeling studies that we hope will offer more insight into the climate dynamics that triggered and sustained such extended periods of drought during the past millennium.</p><img src="https://counter.theconversation.com/content/189222/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Gayatri Kathayat receives funding from the National Natural Science Foundation of China </span></em></p><p class="fine-print"><em><span>Ashish Sinha receives funding from the US National Science Foundation and the Chinese Academy of Sciences President's International Fellowship Initiative.</span></em></p>As water dripped in a remote cave, it left behind evidence of every monsoon season for a millennium. Scientists say it holds a warning for a country about to become the most populous on Earth.Gayatri Kathayat, Associate Professor of Global Environmental Change, Xi'an Jiaotong UniversityAshish Sinha, Professor of Earth and Climate Sciences, California State University, Dominguez HillsLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1898532022-09-06T17:30:10Z2022-09-06T17:30:10ZFlooding in Pakistan shows that climate adaptation requires international support and regional co-operation<figure><img src="https://images.theconversation.com/files/483028/original/file-20220906-4758-8tqxnu.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C6000%2C3997&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A woman wades through a flooded area after heavy rains in Sindh province, Pakistan. </span> <span class="attribution"><span class="source">(AP Photo/Fareed Khan)</span></span></figcaption></figure><iframe style="width: 100%; height: 100px; border: none; position: relative; z-index: 1;" allowtransparency="" allow="clipboard-read; clipboard-write" src="https://narrations.ad-auris.com/widget/the-conversation-canada/flooding-in-pakistan-shows-that-climate-adaptation-requires-international-support-and-regional-co-operation" width="100%" height="400"></iframe>
<p>The monsoon flooding in Pakistan has been referred to as a “<a href="https://www.bbc.com/news/world-asia-62722117">monsoon on steroids</a>” and described as a “<a href="https://www.theguardian.com/environment/2022/aug/29/monster-monsoon-why-the-floods-in-pakistan-are-so-devastating">monster monsoon</a>.” These names reflect the wide devastation it has caused. </p>
<p>This flooding has been fuelled by the <a href="https://www.worldweatherattribution.org/climate-change-made-devastating-early-heat-in-india-and-pakistan-30-times-more-likely/">hottest weather recorded</a> during March and April this year. This heat accelerated glacier melting in Pakistan’s north, followed by unprecedented rainfall patterns in many parts of the country during July and August. </p>
<p>Human-induced climate change has caused these unusual weather events: <a href="https://www.worldweatherattribution.org/climate-change-made-devastating-early-heat-in-india-and-pakistan-30-times-more-likely/">a one in 100-year heat wave</a> and rainfall over nine times the average rainfall in the southeastern Sindh province. </p>
<p>The loss of lives since mid-June 2022 currently stands at <a href="https://www.dawn.com/news/1708556/authorities-prepare-for-more-evacuations-as-water-level-in-manchhar-lake-continues-to-rise">over 1,300</a>. And it is estimated that <a href="https://www.unhcr.org/news/stories/2022/9/6311c7f54/pakistans-disastrous-floods-uproot-refugees-citizens.html">the number of people affected by the floods is around 33 million</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/482841/original/file-20220905-20-lk16u5.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="a graph comparing the average rainfall with 2022 levels in various Pakistani provinces" src="https://images.theconversation.com/files/482841/original/file-20220905-20-lk16u5.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/482841/original/file-20220905-20-lk16u5.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=345&fit=crop&dpr=1 600w, https://images.theconversation.com/files/482841/original/file-20220905-20-lk16u5.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=345&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/482841/original/file-20220905-20-lk16u5.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=345&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/482841/original/file-20220905-20-lk16u5.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=433&fit=crop&dpr=1 754w, https://images.theconversation.com/files/482841/original/file-20220905-20-lk16u5.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=433&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/482841/original/file-20220905-20-lk16u5.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=433&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Data gathered by the Pakistan Meteorological Department show the unusually high levels of rainfall in 2022.</span>
<span class="attribution"><span class="source">(Z. Adeel)</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>A fraction</h2>
<p>In 2019, Pakistan’s greenhouse gas emissions stood at about <a href="https://data.worldbank.org/indicator/EN.ATM.GHGT.KT.CE?locations=PK">433 million tonnes of carbon dioxide equivalents per year</a> — this is 0.9 per cent of the global emissions. While Pakistan contributes a small fraction of the global greenhouse emissions, it is disproportionately impacted by climate change. </p>
<p>The onus of helping Pakistan recover from this tragedy, therefore, rests on the international community.</p>
<p>Having studied the <a href="http://www.cec.org/publications/cec-policy-brief-on-flood-costing-understanding-the-comprehensive-economic-impact-of-floods-in-canada-mexico-and-the-united-states/">economic impacts of extreme floods in North America</a> and the history of <a href="https://doi.org/10.1007/978-3-319-32845-4">water management in the Indus basin (which lies between Pakistan, India, China and Afghanistan)</a>, I can safely state that the current estimate of US$10 billion in damages likely significantly underrepresents the comprehensive cost of this disaster. </p>
<p>A more in-depth analysis is often required to determine the long-term impacts on infrastructure, loss of revenue due to supply-chain disruptions, costs of disruption to manufacturing and loss of productivity as people are displaced. </p>
<h2>Inadequate infrastructure</h2>
<p>In 2010, Pakistan was also hit with <a href="https://www.dawn.com/news/1707390/pakistans-history-of-disasters-and-the-lessons-we-fail-to-learn">extreme flooding</a>, which resulted in the loss of 1,985 lives and over US$ 10 billion in damages. These recurring events raise questions about systemic and strategic responses to mitigate against future flood events. </p>
<p>It is apparent that flood management infrastructure is inadequate, and is compounded by the lack of capacity for timely responses from public authorities. In this specific situation, while the National Disaster Management Authority (NDMA) in Pakistan issued its <a href="http://cms.ndma.gov.pk/news/ml-m-30-jwn-s-mwn-swn-barshw-slsl-a-am-an-mtalq-adarw-w-alr-r-n-da-t-a-n-a-m-a">earliest and somewhat generic alert</a> about extensive monsoon rainfalls on June 28, it did not recognize the severity until mid- to late-July.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/483073/original/file-20220906-26-m4ebyl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="people wade through a flooded city street" src="https://images.theconversation.com/files/483073/original/file-20220906-26-m4ebyl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/483073/original/file-20220906-26-m4ebyl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/483073/original/file-20220906-26-m4ebyl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/483073/original/file-20220906-26-m4ebyl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/483073/original/file-20220906-26-m4ebyl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/483073/original/file-20220906-26-m4ebyl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/483073/original/file-20220906-26-m4ebyl.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">People wade through a flooded road after heavy rains, in Karachi, Pakistan on July 25, 2022. Monsoon rains inundated several low-lying neighborhoods, flooding even the city’s upscale areas and disrupting normal life.</span>
<span class="attribution"><span class="source">(AP Photo/Fareed Khan)</span></span>
</figcaption>
</figure>
<p>While these alerts triggered <a href="http://cms.ndma.gov.pk/news/mwrkh-20-a-st-2022-a-n-a-m-a-janb-s-s-lab-mtathr-n-le-n-am-amdad-fra-m-jar">responses by the NDMA</a> for affected areas in early August, their aid was designed for tens of thousands of people, whereas those affected were in the millions. Pakistan’s armed forces stepped up to <a href="https://www.cbc.ca/news/world/pakistan-flood-disaster-child-deaths-water-borne-diseases-homelessness-refugees-1.6570750">undertake a major role in the humanitarian relief efforts</a>.</p>
<h2>Systematic building</h2>
<p>United Nations Secretary General António Guterres launched a <a href="https://www.bbc.com/news/world-asia-62722117">US$ 160 million appeal</a> at the end of August. The Canadian federal government announced <a href="https://www.canada.ca/en/global-affairs/news/2022/08/canada-announces-5-million-in-funding-for-humanitarian-assistance-in-response-to-flooding-in-pakistan.html">$5 million in funding</a> for humanitarian assistance, in addition to contributing to the U.N. emergency response fund.</p>
<p>While these humanitarian initiatives are very important in addressing the immediate needs related to disaster relief, they pale in comparison to the scale of the upcoming challenge for Pakistan. </p>
<p>The scope of the response needed to recover from this disastrous event is apparently beyond the capacity of various agencies in Pakistan. There is a need to systematically build Pakistan’s capacity to cope with climate change-related flooding in the future. </p>
<p>This support needs to take the shape of financial resourcing, technical assistance and human capacity building. It should take two approaches. The first involves building effective early-response mechanisms that allow communities to react in a reasonable timeframe. At the same time, support should enhance water management infrastructure to manage excess water in flooding events and help with droughts in dry years.</p>
<p>While the NDMA and the Pakistan Meteorological Department have made considerable strides in <a href="https://ffd.pmd.gov.pk/home">developing early-warning systems</a>, significantly more needs to be done at the community level. There is a need for broad-based and grassroot-level community organizations that can support timely evacuation from flooded areas and provide immediate humanitarian assistance.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/483026/original/file-20220906-14-z1jwf1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="women stand on a sandy beach with household belongings piled high on a cart" src="https://images.theconversation.com/files/483026/original/file-20220906-14-z1jwf1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/483026/original/file-20220906-14-z1jwf1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=404&fit=crop&dpr=1 600w, https://images.theconversation.com/files/483026/original/file-20220906-14-z1jwf1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=404&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/483026/original/file-20220906-14-z1jwf1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=404&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/483026/original/file-20220906-14-z1jwf1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=508&fit=crop&dpr=1 754w, https://images.theconversation.com/files/483026/original/file-20220906-14-z1jwf1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=508&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/483026/original/file-20220906-14-z1jwf1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=508&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Women gather salvaged belongings from their flooded home after monsoon rains, in Sindh Province, Pakistan.</span>
<span class="attribution"><span class="source">(AP Photo/Fareed Khan)</span></span>
</figcaption>
</figure>
<h2>Climate change adaptation</h2>
<p>In the 2015 climate conference in Paris, the world leaders committed to provide <a href="https://www.oecd.org/climate-change/finance-usd-100-billion-goal/">US$ 100 billion annually to combat climate change</a>. </p>
<p>Building Pakistan’s water infrastructure — particularly new water reservoirs and dams — falls under the overall theme of adaptation to climate change. While the funding mobilized since then <a href="https://doi.org/10.1038/d41586-021-02846-3">has been a fraction of that commitment</a>, a significant proportion should be directed to developing countries like Pakistan that are disproportionately impacted by climate change. </p>
<p>There is also growing recognition that some of the responses to such natural disasters must come from within the region. Countries in South Asia, particularly those in the Indus Basin, should pool their technological, human and financial resources to mount more immediate and targeted disaster responses. </p>
<p>Despite the geopolitical tensions in the region, shared responses to humanitarian crises can be a mechanism to build mutual co-operation and trust.</p><img src="https://counter.theconversation.com/content/189853/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Zafar Adeel receives funding from the Commission for Environmental Cooperation (CEC), to study economic impacts of flooding in Canada, Mexico, and the United States. </span></em></p>Pakistan contributes less than one per cent of greenhouse gas emissions, but has disproportionately felt the impact of climate change.Zafar Adeel, Executive Director, Pacific Water Research Centre, Faculty of Environment, Simon Fraser UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1898332022-09-02T16:32:45Z2022-09-02T16:32:45ZPakistan floods: what role did climate change play?<p>Pakistan is experiencing the most devastating and widespread floods in its history, with the <a href="https://www.carbonbrief.org/daily-brief/pakistan-floods-one-third-of-country-is-under-water-minister/">country’s climate minister</a> saying waters have reached across a third of the nation. </p>
<p>The growing <a href="https://reliefweb.int/report/pakistan/pakistan-monsoon-rain-update-gdacs-ndma-pakistan-copernicus-emsr-pmd-echo-daily-flash-30-august-2022">tally of impacts</a> is dire. More than 1,100 people have been killed, a million homes have been destroyed and 33 million people have been directly affected. Total damage estimates exceed US$10 billion (£8.6 billion), and <a href="https://www.economist.com/asia/2022/08/30/pakistan-has-been-hit-by-its-worst-floods-in-recent-memory">further disruption</a> to the country’s economy and critical food production is inevitable. </p>
<p>On August 25, the government declared a <a href="https://www.aljazeera.com/news/2022/8/26/pakistan-floods">national emergency</a>. António Guterres, the UN secretary-general, said that this is a signal to the world to step up climate action, <a href="https://edition.cnn.com/2022/08/29/asia/pakistan-flood-damage-imf-bailout-intl-hnk/index.html">warning</a>: “Today, it’s Pakistan. Tomorrow, it could be your country.” </p>
<p>At a very broad level, this is certainly justified. <a href="https://www.ipcc.ch/report/ar6/wg1/">According to</a> the Intergovernmental Panel on Climate Change (IPCC), extreme rainfall is becoming more frequent and intense in many parts of the world due to human emissions of greenhouse gases. And this effect will continue to increase with emissions. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1563527996064931843"}"></div></p>
<p>However, for individual events that have such profound impacts on society, it is critical to investigate the influence of climate change (or lack thereof) in more detail. While the IPCC statement holds globally, its <a href="https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_SPM.pdf">most recent report</a> states it has only “low confidence” in how much climate change is to blame for increased heavy rains in south Asia. </p>
<p>It is vital we better understand cause and effect in the observed changes, to help us make best use of our finite resources and ultimately save lives and money. </p>
<h2>Record-breaking monsoon rainfall</h2>
<p>It is tempting to ask if an extreme weather event was “caused by” climate change, but this is often the wrong question, at least if you expect a binary answer. Instead, scientists like us ask whether and by how much climate change affected the likelihood and intensity of the event. This is known as “<a href="https://theconversation.com/yes-climate-change-can-affect-extreme-weather-but-there-is-still-a-lot-to-learn-136003">extreme event attribution</a>”.</p>
<p>In this case, the flooding was caused by an extreme monsoon season. Pakistan is on the far western edge of the south Asian monsoon region, with a mostly arid desert climate. It is only sometimes affected by an offshoot of the monsoon, and generally receives far less rainfall than parts of India at the same latitudes.</p>
<p>However, record rainfall fell over Pakistan in several bursts from mid-June to late August with large swathes of the country receiving a completely <a href="https://floodlist.com/asia/pakistan-floods-update-august-2022">unprecedented 500%-700% of their usual August rain</a>. </p>
<h2>Yet another cost of climate change?</h2>
<p>Officials from the Pakistan Meteorological Department <a href="https://www.thenews.com.pk/print/983748-climate-change-blamed-for-above-normal-rains-in-sindh-balochistan">blamed climate change</a> for the unusual monsoon activity and flooding, for a range of reasons.</p>
<p>In 2021, the IPCC reported that there has been a significant increase in heavy rainfall events in south Asia in recent decades. There is <a href="https://www.sciencedirect.com/science/article/pii/S2212094717301068">some evidence</a> that this is due to human-caused climate change. </p>
<p>However, there is limited agreement between different assessed studies, and factors other than climate change, such as <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019GL083875">irrigation</a>, are known to influence monsoons. Confidence is therefore too low to make any concrete attribution statements without further investigation.</p>
<p>Before a dedicated study is available, similar events in the recent past can hold clues to current events. Pakistan last experienced flooding on a similar scale in 2010, which at the time was labelled by Guterres’ predecessor at the UN, Ban Ki-moon, as the <a href="https://www.abc.net.au/radio/programs/am/ban-ki-moon-says-pakistan-disaster-worst-hes-ever/945914">worst disaster he’d ever seen</a>. </p>
<p>Two separate attribution studies <a href="https://journals.ametsoc.org/view/journals/clim/26/9/jcli-d-12-00169.1.xml?tab_body=fulltext-display">assessed</a> this <a href="https://progearthplanetsci.springeropen.com/articles/10.1186/s40645-021-00431-w#Sec2">event</a>. Unfortunately, neither provided evidence that the models used were up to the task. Therefore, even though one of them found an increase due to human climate change, we cannot be very confident in this result. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/482525/original/file-20220902-20-c96ghq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Man with bike wades through water" src="https://images.theconversation.com/files/482525/original/file-20220902-20-c96ghq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/482525/original/file-20220902-20-c96ghq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/482525/original/file-20220902-20-c96ghq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/482525/original/file-20220902-20-c96ghq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/482525/original/file-20220902-20-c96ghq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/482525/original/file-20220902-20-c96ghq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/482525/original/file-20220902-20-c96ghq.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">Hundreds of thousands of homes have been damaged or destroyed.</span>
<span class="attribution"><span class="source">Bilawal Arbab / EPA</span></span>
</figcaption>
</figure>
<p>Clues as to the role of climate change can also come from aspects that contributed to this disaster. There are three main factors.</p>
<p>First, extreme rainfall. A warmer atmosphere holds more moisture. For every degree the atmosphere warms it can hold <a href="https://www.climatesignals.org/climate-signals/atmospheric-moisture-increase">about 6%-7% more moisture</a>, which often results in more rain falling during the most extreme events (south Asia has warmed around <a href="https://link.springer.com/content/pdf/10.1007/978-981-15-4327-2.pdf">0.7°C since 1900</a>). Had this event happened in a world where carbon dioxide concentrations were instead at pre-industrial levels, the rains probably would have been less intense. </p>
<p>Second, the monsoon itself, which is highly complex and variable. It forms in south Asia in the summer, when air over land warms faster than air over the sea, which creates a flow of air onto the land. The winds bring great volumes of moisture that precipitate into deluges when they meet higher ground, especially the Himalayas. </p>
<p>Unusual monsoon rains over Pakistan have some predictability. They occur when multiple phenomena <a href="https://www.nature.com/articles/s41612-021-00211-9">coincide</a>, including a <a href="https://theconversation.com/explainer-el-nino-and-la-nina-27719">La Niña</a> event in the Pacific and large meanders in the high-altitude jet stream, as was the case in both 2010 and this year. </p>
<p>There is <a href="https://journals.ametsoc.org/view/journals/clim/35/3/JCLI-D-21-0200.1.xml">emerging evidence</a> that this confluence of factors may occur more regularly as the climate changes. If such trends continue, then flooding in Pakistan and other <a href="https://theconversation.com/a-climate-scientist-on-the-planets-simultaneous-disasters-from-pakistans-horror-floods-to-europes-record-drought-189626">simultaneous extremes</a> across the northern Hemisphere will happen more often in the future.</p>
<p>Pakistan also experienced extended and brutal heatwaves in May and June this year, which were <a href="https://www.worldweatherattribution.org/climate-change-made-devastating-early-heat-in-india-and-pakistan-30-times-more-likely/">amplified by climate change</a>. This heat amplified the monsoonal “<a href="https://link.springer.com/article/10.1007/s12517-011-0458-5">thermal low</a>” - a low-pressure system created by hot air rising rapidly - which greatly enhanced the flow of moisture-laden air onto <a href="https://www.thenews.com.pk/print/983748-climate-change-blamed-for-above-normal-rains-in-sindh-balochistan">southern Pakistan</a>. </p>
<p>Third, Pakistan has more than <a href="https://earthobservatory.nasa.gov/images/150279/devastating-floods-in-pakistan">7,000 glaciers</a> in its northern mountainous regions. As these glaciers melt, their waters contribute to the flooding. This melting is driven to a large degree by climate change and is especially prominent this year as a result of the heatwave. </p>
<h2>Proactive is far cheaper than reactive</h2>
<p>Pakistan is undoubtedly on the front lines of climate change. In the ongoing flooding, it is clear that climate change has at minimum played a role in amplifying this event. At worst, it created a compounding set of circumstances causing millions of additional people to suffer than otherwise might have.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/482536/original/file-20220902-1338-vvme5p.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Indian Ocean and South Asia map shaded" src="https://images.theconversation.com/files/482536/original/file-20220902-1338-vvme5p.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/482536/original/file-20220902-1338-vvme5p.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=317&fit=crop&dpr=1 600w, https://images.theconversation.com/files/482536/original/file-20220902-1338-vvme5p.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=317&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/482536/original/file-20220902-1338-vvme5p.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=317&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/482536/original/file-20220902-1338-vvme5p.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=398&fit=crop&dpr=1 754w, https://images.theconversation.com/files/482536/original/file-20220902-1338-vvme5p.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=398&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/482536/original/file-20220902-1338-vvme5p.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=398&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Maximum five day rainfall in June–September at 3°C warming.</span>
<span class="attribution"><span class="source">IPCC</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Projections are very clear that with further climate change, Pakistan is a <a href="https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_Chapter11.pdf">hotspot</a> for increases in extreme rainfall. The country must prepare for future flooding to avoid similar or even worse disasters. To do so, international adaptation funding must increase to match rich countries’ overwhelming contribution to this new climate.</p><img src="https://counter.theconversation.com/content/189833/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ben Clarke receives funding from the Natural Environment Research Council.</span></em></p><p class="fine-print"><em><span>Friederike Otto receives funding from the European Climate Foundation and the European Research Council. </span></em></p><p class="fine-print"><em><span>Luke Harrington receives funding from the Ministry of Business, Innovation and Employment.</span></em></p>There are three key ways climate change probably made these floods worse.Ben Clarke, DPhil Candidate in Environmental Research, University of OxfordFriederike Otto, Senior lecturer, Imperial College LondonLuke Harrington, Senior Lecturer in Climate Change, University of WaikatoLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1824262022-05-04T19:09:46Z2022-05-04T19:09:46ZThe Southwest is on fire, with iconic deserts and towns at risk – 3 reasons the 2022 fire season is so early and intense<figure><img src="https://images.theconversation.com/files/461364/original/file-20220504-23-cykjgs.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C2000%2C1332&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Wind quickly spread a blaze that burned homes near Flagstaff, Ariz., in April 2022.</span> <span class="attribution"><a class="source" href="https://newsroom.ap.org/detail/WesternWildfires/f34e271189d54ce4b1b632e499d4a67c/photo">Coconino National Forest via AP</a></span></figcaption></figure><p><em>New Mexico and Arizona are facing a dangerously early fire season. It has left neighborhoods in ashes and is having such devastating effects that <a href="https://www.whitehouse.gov/briefing-room/statements-releases/2022/05/04/president-joseph-r-biden-jr-approves-new-mexico-disaster-declaration/">President Joe Biden issued a disaster declaration</a> for New Mexico. Over <a href="https://gacc.nifc.gov/swcc/predictive/intelligence/daily/UPLOAD_Files_toSWCC/YTD_10_INFORM_2_STATE.pdf">600 fires</a> had broken out in the two states by early May, and large wildfires had burned through hundreds of homes near Ruidoso and Las Vegas, New Mexico, and Flagstaff, Arizona.</em></p>
<p><em>We asked wildfire scientist <a href="https://www.researchgate.net/profile/Molly-Hunter-4">Molly Hunter</a> at the University of Arizona to explain what’s fueling the extreme fire conditions and why risky seasons like this are becoming more common.</em></p>
<h2>Why is this year’s wildfire season in the Southwest so early and intense?</h2>
<p>Historically, fire season in the Southwest didn’t ramp up until late May or June, because fuels that carry fires – primarily woody debris, leaf litter and dead grasses – didn’t fully dry out until then.</p>
<p>Now, the Southwest is seeing more <a href="https://medialibrary.climatecentral.org/resources/western-fire-weather-days-increasing">fires start much earlier</a> in the year. The earlier fire season is <a href="https://nca2014.globalchange.gov/report/regions/southwest">partly due to the warming climate</a>. As temperatures rise, the snow melts more rapidly, more water evaporates into the atmosphere and the grasses and other fuels dry out earlier in the season.</p>
<p>Unfortunately, the earlier timing coincides with when the region commonly experiences <a href="https://www.weather.gov/abq/features_highwind">strong winds</a> that can drive rapid fire growth. Some of the fires we’re seeing this year, like the <a href="https://www.azcentral.com/story/news/local/arizona-wildfires/2022/04/23/tunnel-fire-destroys-30-homes-displaces-families-near-flagstaff/7417799001/">Tunnel Fire</a> near Flagstaff and the fires in New Mexico, are being driven by these really intense wind events. They’re pretty typical winds for spring, but fuels are now really dry and ready to burn.</p>
<figure class="align-center ">
<img alt="Two fire crew members use axes to chop at burning roots on a charred desert landscape." src="https://images.theconversation.com/files/461369/original/file-20220504-21-3br94n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/461369/original/file-20220504-21-3br94n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=398&fit=crop&dpr=1 600w, https://images.theconversation.com/files/461369/original/file-20220504-21-3br94n.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=398&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/461369/original/file-20220504-21-3br94n.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=398&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/461369/original/file-20220504-21-3br94n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=500&fit=crop&dpr=1 754w, https://images.theconversation.com/files/461369/original/file-20220504-21-3br94n.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=500&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/461369/original/file-20220504-21-3br94n.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">Fire crews dig at burning roots in the wake of a fire near Flagstaff, Ariz., in April 2022.</span>
<span class="attribution"><a class="source" href="https://newsroom.ap.org/detail/WesternWildfires/df543b966a4a4115b5e81d2d8dd9a8d4/photo?">Tom Story/Northern Arizona Type 3 Incident Management Team, via AP</a></span>
</figcaption>
</figure>
<p>This year we also have a lot of fuel to burn. Last summer, in 2021, the Southwest had an <a href="https://www.weather.gov/psr/2021MonsoonReview">exceptional monsoon season</a> that left green hillsides and lots of vegetation. By now the grasses and <a href="https://www.usgs.gov/publications/desert-fires-fueled-native-annual-forbs-effects-fire-communities-plants-and-birds-0">forbs</a> that established during the monsoon have dried out, leaving a lot of biomass that can carry a fire. Often in the Southwest, our biggest fire years come when we have a wet period followed by a dry period, like the <a href="https://www.climate.gov/news-features/blogs/enso/april-2022-la-ni%C3%B1a-update-measuring">La Niña conditions</a> we’re experiencing now.</p>
<h2>What role does climate change play?</h2>
<p>In the Southwest, <a href="https://nca2018.globalchange.gov/chapter/25/">climate change</a> has meant warmer, drier conditions. One immediate effect is the lengthening of the fire season. </p>
<p>We now see fires starting in March and April. And if the Southwest doesn’t get a good summer monsoon – the region’s typical period of heavy rainstorms – fire season won’t really stop until we get significant rainfall or snowfall in fall and winter. That means more stress on firefighting resources, and more stress on communities facing fire, smoke and evacuations.</p>
<p>As fire season lengthens, states are also seeing more fires caused by human activities, such as fireworks, sparks from vehicles or equipment, and power lines. <a href="https://theconversation.com/the-fastest-population-growth-in-the-wests-wildland-urban-interface-is-in-areas-most-vulnerable-to-wildfires-173410">More people are moving</a> out into areas that are fire-prone, creating more opportunities for human-caused ignitions.</p>
<figure class="align-center ">
<img alt="Satellite images shows fires burning near Las Vegas, New Mexico, and Los Alamos." src="https://images.theconversation.com/files/461282/original/file-20220504-12-2aqu7w.jpg?ixlib=rb-1.1.0&rect=284%2C220%2C2074%2C1455&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/461282/original/file-20220504-12-2aqu7w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/461282/original/file-20220504-12-2aqu7w.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/461282/original/file-20220504-12-2aqu7w.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/461282/original/file-20220504-12-2aqu7w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/461282/original/file-20220504-12-2aqu7w.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/461282/original/file-20220504-12-2aqu7w.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">By May 4, nearly a quarter-million acres had burned in New Mexico, almost double the state’s 2021 total. Fires shown by satellite and on the map below are near Los Alamos and Las Vegas, N.M.</span>
<span class="attribution"><a class="source" href="https://earthobservatory.nasa.gov/images/149784/wildfires-continue-to-burn-across-new-mexico">NASA</a></span>
</figcaption>
</figure>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/461286/original/file-20220504-15-8yietu.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Map showing several large fires around Santa Fe, New Mexico, including in the town of Las Vegas, New Mexico" src="https://images.theconversation.com/files/461286/original/file-20220504-15-8yietu.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/461286/original/file-20220504-15-8yietu.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=344&fit=crop&dpr=1 600w, https://images.theconversation.com/files/461286/original/file-20220504-15-8yietu.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=344&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/461286/original/file-20220504-15-8yietu.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=344&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/461286/original/file-20220504-15-8yietu.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=432&fit=crop&dpr=1 754w, https://images.theconversation.com/files/461286/original/file-20220504-15-8yietu.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=432&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/461286/original/file-20220504-15-8yietu.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=432&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption"></span>
<span class="attribution"><a class="source" href="https://maps.nwcg.gov/sa/#/%3F/%3F/35.8912/-105.4675/9">National Interagency Fire Center</a></span>
</figcaption>
</figure>
<h2>What effect is the changing fire regime having on the Southwest’s ecosystems?</h2>
<p>When fires burn in areas that didn’t see fire historically, they can transform ecosystems.</p>
<p>People generally don’t think of fire as being a natural part of desert ecosystems, but <a href="https://www.pnas.org/doi/10.1073/pnas.1908253116">grasses are now fueling really big fires</a> in the desert, like Arizona’s <a href="https://www.azcentral.com/picture-gallery/news/local/arizona/2021/06/06/photos-telegraph-fire-burns-tonto-national-forest/7574130002/">Telegraph Fire</a> in 2021. These fires are also spreading farther, and into different ecosystems. The Telegraph Fire started in a desert system, then burned through chaparral and into the mountains, with pine and conifer forest.</p>
<p>Part of the problem is <a href="https://www.pnas.org/doi/10.1073/pnas.1908253116">invasive grasses like buffelgrass and red brome</a> that spread quickly and burn easily. A lot of grass is <a href="https://www.azmirror.com/2019/11/18/arizona-buffelgrass-invasive-grass-a-wildfire-threat-to-sonoran-desert/">now growing in those desert systems</a>, making them more prone to wildfire.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/zBi354Q4RuE?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Invasive buffelgrass is a threat to desert ecosystems and communities.</span></figcaption>
</figure>
<p>When a fire spreads in the desert, some plant species, like mesquite and other brushy plants, can survive. But the saguaro – the iconic cactuses that are so popular in tourist visions of the Southwest – are <a href="https://www.fs.usda.gov/treesearch/pubs/44459">not well adapted to fire</a>, and they often die when exposed to fire. Paloverde trees are <a href="https://www.fs.fed.us/database/feis/plants/shrub/parmic/all.html">also not well adapted</a> to survive fires.</p>
<p>What does comes back quickly is the grasses, both native and invasive. So in some areas we’re seeing a transition from desert ecosystem to a <a href="https://www.tucsonweekly.com/tucson/summer-invaders-increased-fire-risk-threatens-all-inhabitants-of-the-sonoran-desert/Content?oid=30607881">grassland ecosystem</a> that is very conducive to the spread of fire. </p>
<p>The <a href="http://azfiretracker.azcentral.com/mostsignificant-cavecreekcomplex.html">Cave Creek Fire</a> near Phoenix in 2005 is an example where you can see this transition. It burned over 240,000 acres, and if you drive around that area now, you don’t see lot of saguaros. It doesn’t look like desert. It looks like more like annual grassland. </p>
<p>This is an iconic landscape, so the loss affects tourism. It affects wildlife as well. A lot of <a href="https://www.nps.gov/sagu/learn/nature/saguaros_animals.htm">species rely on saguaro</a> for nesting and feeding. <a href="https://www.fs.fed.us/wildflowers/pollinators/pollinator-of-the-month/lesser_long-nosed_bat.shtml">Bats rely on the flowers</a> for nectar.</p>
<h2>What can be done to avoid high fire risk in the future?</h2>
<p>In some respects, people will have to recognize that fire is inevitable.</p>
<p>Fires quickly now surpass our capacity to control them. When winds are strong and the fuels are really dry, there’s only so much firefighters can do to prevent some of these big fires from spreading.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/461372/original/file-20220504-12-76ggpg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A man throws a large log , just cut down, as he and other clear a fire line." src="https://images.theconversation.com/files/461372/original/file-20220504-12-76ggpg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/461372/original/file-20220504-12-76ggpg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/461372/original/file-20220504-12-76ggpg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/461372/original/file-20220504-12-76ggpg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/461372/original/file-20220504-12-76ggpg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/461372/original/file-20220504-12-76ggpg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/461372/original/file-20220504-12-76ggpg.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">People clear trees from around a home as a fire threatens Las Vegas, N.M., on May 2, 2022.</span>
<span class="attribution"><a class="source" href="https://newsroom.ap.org/detail/APTOPIXSpringWildfires/dc1a60758fcf48bfab4f24c1b2c3cc03/photo">AP Photo/Cedar Attanasio</a></span>
</figcaption>
</figure>
<p>Conducting more <a href="https://www.fs.usda.gov/managing-land/prescribed-fire">prescribed fires</a> to clear out potential fuel is one important way to lessen the probability of really big, destructive blazes. </p>
<p>Historically, far more money went into fighting fires than managing the fuels with tactics like thinning and prescribed fire, but the <a href="https://www.doi.gov/wildlandfire/meet-bil-how-bipartisan-infrastructure-law-supports-wildland-fire-management">infrastructure bill</a> signed in 2021 included a huge influx of funding for fuels management. There’s also a push to move some seasonal fire crew jobs to full-time, yearlong positions to conduct thinning and prescribed burns.</p>
<p>Homeowners can also <a href="https://theconversation.com/how-to-build-wildfire-resistant-communities-in-a-warming-world-174582">be better prepared to live with fires</a>. That means maintaining yards and homes by removing debris so they’re less likely to burn. It also means being prepared to evacuate.</p>
<p><em>This article was updated May 5 with Biden issuing the disaster declaration.</em></p><img src="https://counter.theconversation.com/content/182426/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Molly Hunter has received funding from the Bureau of Land Management, National Park Service, U.S. Geological Survey, and U.S. Forest Service. </span></em></p>Fire season is getting longer, and the result is transforming iconic desert ecosystems. The start to 2022 has been so dire, one governor called for a federal disaster declaration.Molly Hunter, Associate Research Professor in Environment and Natural Resources, University of ArizonaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1662222021-10-01T12:12:13Z2021-10-01T12:12:13ZMonsoons make deserts bloom in the US Southwest, but climate change is making these summer rainfalls more extreme and erratic<figure><img src="https://images.theconversation.com/files/423923/original/file-20210929-14-jky5f7.jpg?ixlib=rb-1.1.0&rect=34%2C0%2C3888%2C2584&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Lightning during a monsoon storm in southern Arizona, Saguaro National Park.</span> <span class="attribution"><a class="source" href="https://photolib.noaa.gov/Collections/National-Weather-Service/Other/emodule/627/eitem/17721">Pete Gregoire, NOAA</a></span></figcaption></figure><p>If you’ve never lived in or visited the U.S. Southwest, you might picture it as a desert that is always hot and dry. But this region experiences a monsoon in the late summer that produces thunderstorms and severe weather, much like India’s famous <a href="https://www.britannica.com/science/Indian-monsoon">summer deluges</a>.</p>
<p>And this year, it generated a lot of rain.</p>
<p>July 2021 was the wettest month since record keeping started at the Tucson, Arizona, airport in 1895, with <a href="https://www.wrh.noaa.gov/twc/monsoon/monsoon.php">8.06 inches</a> (205 millimeters) of rainfall – equivalent to 70% of what the city receives in an average year. This year’s monsoon is the third-wettest ever in Tucson, with <a href="https://www.wrh.noaa.gov/twc/monsoon/monsoon.php">12.80 inches</a> (325 millimeters) of rain.</p>
<p>It was completely the opposite in 2020: Tucson had a <a href="https://www.wrh.noaa.gov/twc/climate/monthly/2020.php">dry “non-soon”, with less than 2 inches of rain</a>. These conditions and <a href="https://www.wrh.noaa.gov/twc/climate/monthly/2020.php">record high temperatures</a> fueled Arizona’s <a href="https://www.azcentral.com/story/news/local/arizona-weather/2021/01/27/2020-was-arizonas-worst-wildfire-seasons-decade/4286395001/">largest wildfire season in a decade</a>, including the <a href="https://tucson.com/news/local/one-year-later-researchers-chart-damage-recovery-from-bighorn-fire/article_b8d9bca0-bfef-11eb-878f-2b4fa4e1ae5c.html">Bighorn Fire</a>, which decimated over 60% of the forest in the Catalina Mountains north of Tucson. </p>
<p>Our monsoon system impacts some 20 million people in the Southwest. As researchers studying <a href="https://scholar.google.com/citations?view_op=list_works&hl=en&user=bV991b0AAAAJ">water</a> and <a href="https://scholar.google.com/citations?user=ERu_i_kAAAAJ&hl=en">climate</a>, we investigate monsoon prediction, which is becoming more complicated due to climate change. Understanding monsoons is critical for educating communities about their <a href="https://storymaps.arcgis.com/stories/a3d5f96dfde449908597a691eda0ef82">benefits and risks</a>, and about how to stay safe from effects like flash flooding.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/5OzJhagG5bQ?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">During the North American monsoon season, the dry U.S. Southwest can suddenly turn very wet.</span></figcaption>
</figure>
<h2>From dry to wet</h2>
<p>The word <a href="https://www.wrh.noaa.gov/twc/monsoon/monsoon_whatis.php">monsoon</a> comes from the Arabic word mausim, or season. Its most traditional use is to describe the large-scale wind shift into the Indian subcontinent from the ocean that coincides with intense summer rains there. But monsoons also occur in Africa, Australia and South America, as well as in <a href="https://doi.org/10.1175/1520-0477(1997)078%3C2197:TNAM%3E2.0.CO;2">Mexico and the southwestern U.S.</a>.</p>
<p>Monsoonal circulations carry warm, moist air inland from the ocean, which causes rainfall in the summer season. In the Southwest, this pattern starts when an area of high pressure, called a monsoon ridge, builds over the mountainous areas of Mexico and moves toward the western U.S. </p>
<p>In May and June, when the center of the ridge is directly overhead, the Southwest is very hot and dry. Monsoon rains begin when the warm, moist air moves into the region on the southern side of the ridge. The monsoon in Arizona officially begins June 15 and ends Sept. 30, with most rainfall usually occurring in July and August.</p>
<p>The monsoon has been vital to southwestern ecosystems for <a href="https://doi.org/10.1038/s41561-018-0220-7">thousands of years</a>. Many species have evolved and adapted to <a href="https://www.desertmuseum.org/books/nhsd_summer.php">take advantage of monsoon rains</a>. The first storms signal milkweed plants to bloom, attracting butterflies to lay their eggs. <a href="https://www.researchgate.net/publication/325828487_Notes_on_Reproduction_of_Great_Plains_Toads_Anaxyrus_cognatus_Anura_Bufonidae_from_Southerrn_Arizona">Great Plains toads</a> and <a href="https://doi.org/10.1007/s00442-017-3969-2">red-spotted tadpoles</a> start their reproductive cycles in rain-filled puddles. Cactus fruits and <a href="https://news.arizona.edu/story/bug-bonanza-7-big-colorful-critters-try-spot-monsoon-season">insects</a> provide food for hummingbirds, white-winged doves and many other birds and animals.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/423924/original/file-20210929-16-ncozqx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Flowers in a meadow under blue skies." src="https://images.theconversation.com/files/423924/original/file-20210929-16-ncozqx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/423924/original/file-20210929-16-ncozqx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/423924/original/file-20210929-16-ncozqx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/423924/original/file-20210929-16-ncozqx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/423924/original/file-20210929-16-ncozqx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/423924/original/file-20210929-16-ncozqx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/423924/original/file-20210929-16-ncozqx.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">Wildflowers blooming near Flagstaff, Ariz., on Aug. 26, 2021, during an intense monsoon season.</span>
<span class="attribution"><a class="source" href="https://newsroom.ap.org/detail/SouthwestMonsoon/9170d798fdc7456e991c413d5f2ab373/photo">AP Photo/ Felicia Fonseca</a></span>
</figcaption>
</figure>
<h2>Floods in the desert</h2>
<p>Monsoon thunderstorms occur when clouds develop over mountains during the day, producing rain in the afternoon and early evening. They create unique and severe dangers in the desert environment. </p>
<p>Flash flooding occurs when dry soil can’t quickly absorb short-lived, high-intensity downpours. Washes and arroyos – drainage channels that are dry except during heavy rainstorms – can turn into raging currents within minutes, strong enough to carry away cars and people.</p>
<p>Strong thunderstorms can generate microbursts – strong surface winds that gust near hurricane force. They may also trigger dust storms known as <a href="https://www.britannica.com/science/haboob">haboobs</a> – giant walls of dust a mile or more high that reduce visibility to near zero. </p>
<p>The dry, gusty thunderstorms that herald the beginning of the monsoon can start and spread wildfires. One of these storms ignited the infamous <a href="https://sites.google.com/site/yarnellreport/">Yarnell Hill Fire</a> in June 2013, which killed 19 firefighters. Monsoon rains on fire burn scars can trigger mud and debris flows, compounding the initial wildfire damage.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1420967415618281481"}"></div></p>
<p>The atmospheric circulation pattern in July and August 2021 was <a href="https://doi.org/10.1175/1520-0434(1995)010%3C0763:LSPAWS%3E2.0.CO;2">especially favorable for an active monsoon and severe weather</a> in the Southwest. Most of southern Arizona experienced torrential rains over multiple days and weeks. These storms caused <a href="https://twitter.com/WeatherNation/status/1415415808348639234">flash flooding</a>, <a href="https://twitter.com/WeatherNation/status/1413845467012780035">high winds</a>, <a href="https://twitter.com/lorigraceaz/status/1414045200456978433">dust storms</a>, <a href="https://twitter.com/PriscillaCasper/status/1420913070721835015">mud and debris flows</a> and <a href="https://twitter.com/AsteroidDave/status/1417700968876048389">heavy lightning</a>. Emergency responders carried out <a href="https://twitter.com/TucsonFireDept/status/1428499063771598854">almost 100 swift-water rescues in Tucson</a>. Forecasters <a href="https://climas.arizona.edu/podcast/sept-2021-southwest-climate-podcast-generational-monsoon-over">in Phoenix issued more than 100 flash flood warnings in August</a>.</p>
<p>This year’s record monsoon also brought benefits. It replenished local water supplies throughout Arizona, which is in an <a href="https://twitter.com/DroughtGov/status/1433529357943795712">intensive long-term drought</a>. In the Tucson Basin, the monsoon generated <a href="https://new.azwater.gov/sites/default/files/Tucson%20Model%20Report_No_24_v2_1.pdf">sustained flows in tributaries of the Santa Cruz River</a>, which <a href="https://www.kgun9.com/absolutely-az/understanding-monsoon-and-where-all-the-rainwater-goes">helped to recharge groundwater</a>. Water reserves <a href="https://www.abc15.com/weather/impact-earth/srp-lake-levels-up-thanks-to-wet-monsoon">rose by 5%</a> in reservoirs managed by the Salt River Project, which supplies water to more then 2 million people in central Arizona, at a time when others elsewhere in the West are <a href="https://theconversation.com/as-colorado-river-basin-states-confront-water-shortages-its-time-to-focus-on-reducing-demand-165646">dropping to record lows</a>.</p>
<p>Monsoon rains also brought the Sonoran desert back to life, including areas where the 2020 <a href="https://www.washingtonpost.com/climate-solutions/interactive/2021/saguaro-cactus-climate-change/">Bighorn fire killed thousands of Saguaros</a>. </p>
<h2>The future of the monsoon</h2>
<p>Forecasting the monsoon and how it may change is challenging. High-resolution atmospheric models that explicitly simulate individual thunderstorms, including our <a href="http://www.atmo.arizona.edu/?id=wrf&section=weather">own regional modeling system at University of Arizona</a>, have greatly improved daily weather forecasts in recent decades. But it is still virtually impossible to predict exactly when and where storms will occur on a given day.</p>
<p>It’s also essentially impossible to forecast months in advance how strong monsoon rains will be. This year, long-range forecasts <a href="https://twitter.com/NWSCPC/status/1410313699680690178">didn’t start to trend wet until mid- to late June</a>. Climate change is making monsoon rain more extreme and variable, driven by hotter summers and characterized by <a href="http://dx.doi.org/10.1007/s40641-019-00135-w">less frequent but more intense storms</a>.</p>
<p>If recent years are any indication, our region is already experiencing these effects, with <a href="https://www.climate.gov/news-features/event-tracker/record-breaking-june-2021-heatwave-impacts-us-west">record heat waves</a>, <a href="https://apnews.com/article/ca-state-wire-arizona-fires-wildfires-environment-and-nature-8dcb89fd5ded4c632155c3478d8ba3ee">larger and catastrophic wildfires</a>, and a monsoon that is basically nonexistent one year, then produces record rainfall and severe weather the next. Such shifts are exacerbating people’s exposure to weather and climate extremes in the Southwest. </p>
<p>The big concern is whether a more extreme and erratic monsoon will cause an increase in threshold points of failure – for example, flood control infrastructure that collapses from intense rainfall, or wildfires so devastating that forests can’t recover. Clearly understanding these types of risk is critical to creating a more resilient and sustainable future for the Southwest.</p>
<p>[<em>Over 110,000 readers rely on The Conversation’s newsletter to understand the world.</em> <a href="https://theconversation.com/us/newsletters/the-daily-3?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=100Ksignup">Sign up today</a>.]</p><img src="https://counter.theconversation.com/content/166222/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Christopher L. Castro receives funding from the US Department of Defense's Strategic Environmental Research and Development Program.</span></em></p><p class="fine-print"><em><span>Diana Zamora-Reyes 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>Monsoons are weather patterns that bring thunderstorms and heavy rains to hot, dry areas when warm, moist ocean air moves inland. They’re challenging to forecast, especially in a changing climate.Diana Zamora-Reyes, PhD Candidate in Hydrology, University of ArizonaChristopher L. Castro, Professor of Hydrology and Atmospheric Sciences, University of ArizonaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1631642021-09-07T19:11:09Z2021-09-07T19:11:09ZWildfire burn scars can intensify and even create thunderstorms that lead to catastrophic flooding – here’s how it works<figure><img src="https://images.theconversation.com/files/418962/original/file-20210901-25-1bec74e.jpg?ixlib=rb-1.1.0&rect=0%2C13%2C4599%2C3153&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Parts of Lake Elsinore, California, were overrun with muddy floodwater after a storm hit the Holy Fire burn scar in 2018.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/the-holy-fire-burn-scar-is-seen-above-amorose-street-as-news-photo/1078691058">Jennifer Cappuccio Maher/Digital First Media/Inland Valley Daily Bulletin via Getty Images</a></span></figcaption></figure><p>Wildfires burn millions of acres of land every year, leaving changed landscapes that are prone to flooding. Less well known is that these already vulnerable regions can also intensify and in some cases initiate thunderstorms. </p>
<p>Wildfire burn scars are often left with little vegetation and with a darker soil surface that <a href="https://www.fs.fed.us/rm/pubs/rmrs_gtr042_4.pdf">tends to repel</a> rather than absorb water. These changes in vegetation and soil properties leave the land <a href="https://www.weather.gov/riw/burn_scar_flooding">more susceptible to flooding and erosion</a>, so less rainfall is necessary to produce a devastating flood and <a href="https://theconversation.com/post-fire-mudslide-problems-arent-new-and-likely-to-get-worse-90048">debris flow</a> than in an undisturbed environment.</p>
<p>Burn scars can also initiate or invigorate thunderstorms, raising the risk both of flooding and of lightning that could spark more fires in surrounding areas, as my research with fellow <a href="https://www.comet.ucar.edu/who_director.php">atmospheric scientist Elizabeth Page</a> has shown.</p>
<h2>Factors contributing to thunderstorms</h2>
<p>Three things contribute to the potential for burn scars to fuel thunderstorms: lack of vegetation, reduced soil moisture and lower surface albedo – essentially how well it reflects sunlight. When burned soil is darker, it absorbs more energy from the sun.</p>
<p>These factors contribute to higher surface temperatures over the burn scar area relative to unburned areas nearby. The temperature difference can drive air currents, causing convection – the motion of warmer air rising and cooler air sinking. When that rising <a href="https://doi.org/10.1016/j.atmosres.2015.04.016">warm air draws in more humid air</a> from surrounding areas, it <a href="https://www.metoffice.gov.uk/weather/learn-about/weather/how-weather-works/what-is-convection">can produce cumulonimbus clouds and even thunderstorms</a> that can trigger rain and flooding.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/QxdhbR-vLnM?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Fire officials explain how burned land becomes more flood prone.</span></figcaption>
</figure>
<p>In an <a href="https://doi.org/10.1175/2007MWR2218.1">analysis of a flash flood</a> that occurred on burn scars in Australia in 2003, scientists found that the soil’s moisture was low and its albedo in the burn area had fallen from 0.2 to 0.08. To <a href="https://www.britannica.com/science/albedo">put that into perspective</a>, charcoal has an albedo of about 0.04 and fresh snow is nearly the maximum of 1. When the scientists simulated those changes in a computer model, they found that if the land hadn’t been burned, just over a tenth of an inch of rain would have fallen. Instead, those changes led to 1.25 inches and severe flooding.</p>
<p>Studies have found that the intensity of this effect of burn scars on storm potential decreases over time, but the risk remains until the vegetation regrows.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/419868/original/file-20210907-23-y0ypzp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A view from an airplane of hillsides, some dark from burning, other still green, with roads winding through them." src="https://images.theconversation.com/files/419868/original/file-20210907-23-y0ypzp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/419868/original/file-20210907-23-y0ypzp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/419868/original/file-20210907-23-y0ypzp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/419868/original/file-20210907-23-y0ypzp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/419868/original/file-20210907-23-y0ypzp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/419868/original/file-20210907-23-y0ypzp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/419868/original/file-20210907-23-y0ypzp.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">Burn scars from California wine country’s 2019 Kincade Fire are still evident in 2021.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/an-aerial-view-of-wildfire-burn-scars-from-the-kincade-fire-news-photo/1317732396">Jane Tyska/Digital First Media/East Bay Times via Getty Images</a></span>
</figcaption>
</figure>
<h2>Riding the thermals</h2>
<p>When I used to pilot sailplanes, also known as gliders, I often rode the thermals – upward currents of warm air – in the Santa Catalina Mountains near Tucson and in Colorado’s Front Range. The best locations for catching thermals were on the south and southwest slopes of rugged terrain, where the thermals became chutes of rapidly rising air.</p>
<p>A wildfire in one of these locations would burn more intensely because of the swift air currents, leaving a dark, <a href="https://doi.org/10.2136/sssaj2004.1729">water-repelling surface</a> with little vegetation behind. With moisture from the <a href="https://www.weather.gov/abq/northamericanmonsoon-intro">Southwest Monsoon</a> that arrives in the region in late summer, these thermal chutes, intensified by burn scars, are prime locations for initiating or intensifying storm-producing cumulonimbus clouds and flooding.</p>
<p>In these arid regions, plant recovery may take three to five years or more, particularly in locations where intense fires burned on south- and west-facing slopes where sunlight is more intense. Many of the record-breaking 2020 wildfires in Colorado and Arizona occurred in mountainous terrain where flash flooding on burn scars has been deadly in the past. These areas will continue to be of particular concern over the next few years.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/419866/original/file-20210907-27-1ndu0q5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="People search through damaged homes and vehicles, including an old truck nose down in the foundation of a home that's no longer there." src="https://images.theconversation.com/files/419866/original/file-20210907-27-1ndu0q5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/419866/original/file-20210907-27-1ndu0q5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/419866/original/file-20210907-27-1ndu0q5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/419866/original/file-20210907-27-1ndu0q5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/419866/original/file-20210907-27-1ndu0q5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/419866/original/file-20210907-27-1ndu0q5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/419866/original/file-20210907-27-1ndu0q5.jpg?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"></a>
<figcaption>
<span class="caption">Flooding and mud from heavy rain on a burn scar damaged homes in Manitou Springs, Colorado, in 2013. The region was hit with flooding again in 2018.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/aug-10-crews-stand-on-the-foundation-of-a-home-that-was-news-photo/175984705">Kathryn Scott Osler/The Denver Post via Getty Images</a></span>
</figcaption>
</figure>
<h2>The effects can linger</h2>
<p>How long burn scars will continue to fuel storms depends on how arid the region is and how quickly vegetation recovers.</p>
<p>Forecasters, emergency responders and people living in and near wildfire burn scars need to be aware that these areas are at risk both for potential major flooding and <a href="https://theconversation.com/post-fire-mudslide-problems-arent-new-and-likely-to-get-worse-90048">debris flows</a>, and for invigorated storms with a potential for heavy precipitation.</p>
<p><em>This article was updated to correct a date in the Manitou Springs photo caption to 2018.</em></p>
<p>[<em>Get our best science, health and technology stories.</em> <a href="https://theconversation.com/us/newsletters/science-editors-picks-71/?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=science-best">Sign up for The Conversation’s science newsletter</a>.]</p><img src="https://counter.theconversation.com/content/163164/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>William R. Cotton received funding from the National Science Foundation. </span></em></p>An atmospheric scientist and sailplane pilot describes why large areas of burned land can produce clouds and rainstorms.William R. Cotton, Professor Emeritus of Meteorology, Colorado State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1261412019-11-12T14:47:19Z2019-11-12T14:47:19ZThe East Asian monsoon is many millions of years older than we thought<figure><img src="https://images.theconversation.com/files/301317/original/file-20191112-178532-a5cjd9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Tanya Bill / Shutterstock</span></span></figcaption></figure><p>The East Asian monsoon covers much of the largest continent on Earth leading to rain in the summer in Japan, the Koreas and lots of China. Ultimately, more than 1.5 billion people depend on the water it provides for agriculture, industry and hydroelectric power. </p>
<p>Understanding the monsoon is essential. That is why colleagues and I recently reconstructed its behaviour throughout its 145m-year history, in order to better understand how it acts in response to changes in geography or the wider climate in the very long term, and what that might mean for the future. </p>
<p>Our study, published in the journal <a href="https://advances.sciencemag.org/content/5/10/eaax1697/tab-article-info">Science Advances</a> indicates that the East Asian monsoon is much older and more varied than previously thought. Until quite recently the general consensus was that the monsoon came into being around <a href="https://www.sciencedirect.com/science/article/pii/S2468265917301142">23m years ago</a>, some time after the Tibetan Plateau was formed.</p>
<p>However, we show that it has been ever present for at least the past 145m years (except during the Late Cretaceous: the era of <em>T. Rex</em>), regardless of whether there was a Tibetan Plateau or how much CO₂ was in the atmosphere. </p>
<h2>What is a monsoon?</h2>
<p>At its most simple level a monsoon is a highly seasonal distribution in precipitation leading to a distinct “wet” and “dry” seasons – the word even derives from the Arabic “mausim”, translated as “season”. </p>
<p>The East Asian monsoon is a “sea breeze monsoon”, the most common type. They form because land and sea heat up at different rates, so high pressure forms over the sea and low pressure over land which results in wind blowing onshore in the summer.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/301322/original/file-20191112-178516-1o4ntuo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/301322/original/file-20191112-178516-1o4ntuo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/301322/original/file-20191112-178516-1o4ntuo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=353&fit=crop&dpr=1 600w, https://images.theconversation.com/files/301322/original/file-20191112-178516-1o4ntuo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=353&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/301322/original/file-20191112-178516-1o4ntuo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=353&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/301322/original/file-20191112-178516-1o4ntuo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=444&fit=crop&dpr=1 754w, https://images.theconversation.com/files/301322/original/file-20191112-178516-1o4ntuo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=444&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/301322/original/file-20191112-178516-1o4ntuo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=444&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">It’s the world’s largest, highest plateau.</span>
<span class="attribution"><span class="source">Rashevskyi Viacheslav / shutterstock</span></span>
</figcaption>
</figure>
<p>Although The Tibetan Plateau is not strictly needed to form the East Asian monsoon it can serve to enhance it. At 5km or more above sea level, the plateau simply sits much higher in the atmosphere and thus the air above it is heated much more than the same air would be at a lower elevation (consider the ground temperature in Tibet compared to the freezing air 5km above your head). As that Tibetan air is warmer than the surrounding cold air it rises and acts as a heat “pump”, sucking more air in to replace it and enhancing the monsoon circulation. </p>
<h2>Changes over the (millions of) years</h2>
<p>We found the intensity of the monsoon has varied significantly over the past 145m years. At first, it was around 30% weaker than today. Then, during the Late Cretaceous 100-66m years ago, a huge inland sea covered much of North America and weakened the Pacific trade winds. This caused East Asia to become very arid due to the monsoon disappearing. </p>
<p>However, rainfall patterns changed substantially after the Indian tectonic plate collided into the Asian continent around 50m years ago, forming the Himalayas and the Tibetan Plateau. As the land rose up, so did the strength of the monsoon. Our results suggest that 5-10m years ago there were “super-monsoons” with rainfall 30% stronger than today. </p>
<p>But how can we be sure that such changes were caused by geography, and not elevated carbon dioxide concentrations? To test this, we again modelled the climate for all different time periods (roughly every 4m years) and increased or reduced the amount of CO₂ in the atmosphere to see what effect this had on the monsoon. In general, irrespective of time period chosen, the monsoon showed little sensitivity (-1% to +13%) to changes in CO₂ compared to the impact of changes in regional geography. </p>
<h2>Climate models are working</h2>
<p>The monsoon in East Asia is mainly a result of its favourable geographic position and regional topography – though our work shows that CO₂ concentrations do have an impact, they are secondary to tectonics. </p>
<p>The past can help us better understand how the monsoon will behave as the climate changes – but its not a perfect analogue. Although rainfall increased almost every time CO₂ doubled in the past, each of these periods was unique and dependent on the specific geography at the time. </p>
<p>The reassuring thing is that climate models are showing agreement with geological data through the past. That means we have greater confidence that climate models are able to accurately predict how the monsoon will respond over the next century as humans continue to emit more CO₂ into the atmosphere.</p><img src="https://counter.theconversation.com/content/126141/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Alex Farnsworth receives funding from The Natural Environment Research Council (NERC).</span></em></p>Scientists have reconstructed the monsoon over 145m years – and found it predates the Himalayas.Alex Farnsworth, Postdoctoral Research Associate in meteorology, University of BristolLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1135042019-03-18T16:31:08Z2019-03-18T16:31:08ZIndian summer monsoon amplified global warming 130,000 years ago, helping end ice age<figure><img src="https://images.theconversation.com/files/264376/original/file-20190318-28505-1by2fua.jpg?ixlib=rb-1.1.0&rect=5%2C0%2C3988%2C2652&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Monsoon clouds approach in India.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/view-lake-distant-cloud-approaching-654600133">Manoj Felix/Shutterstock</a></span></figcaption></figure><p>The past may be a surprisingly useful guide for predicting responses to future climate change. This is especially important for places where extreme weather has been the norm for a long time, such as the Indian subcontinent. Being able to reliably predict summer monsoon rainfall is critical to plan for the devastating impact it can have on the 1.7 billion people who live in the region. </p>
<p><a href="https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/97JC02719">The onset of India’s summer monsoon</a> is linked to heat differences between the warmer land and cooler ocean, which causes a shift in prevailing wind direction. Winds blow over the Indian Ocean, picking up moisture, which falls as rain over the subcontinent from June to September.</p>
<p>The monsoon season can bring drought and food shortages or severe flooding, depending on how much rain falls and in what duration. Understanding how the monsoon responded to an abrupt climate transition in the past can therefore help scientists better understand its behaviour in the future.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/264392/original/file-20190318-28479-cur6ci.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/264392/original/file-20190318-28479-cur6ci.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/264392/original/file-20190318-28479-cur6ci.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=147&fit=crop&dpr=1 600w, https://images.theconversation.com/files/264392/original/file-20190318-28479-cur6ci.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=147&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/264392/original/file-20190318-28479-cur6ci.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=147&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/264392/original/file-20190318-28479-cur6ci.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=184&fit=crop&dpr=1 754w, https://images.theconversation.com/files/264392/original/file-20190318-28479-cur6ci.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=184&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/264392/original/file-20190318-28479-cur6ci.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=184&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Maharashtra, India on May 28 2010, during the dry season.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/File:MatheranPanoramaPointDrySeason.JPG">Arne Hückelheim/Wikipedia</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>When we researched this weather system’s ancient past, we found it was highly sensitive to climate warming 130,000 years ago. <a href="https://www.nature.com/articles/s41561-019-0319-5">Our new study</a> published in Nature Geoscience showed that the Indian summer monsoon pulled heat and moisture into the northern hemisphere when Earth was entering a warmer climate around 130,000 years ago. This caused tropical wetlands to expand northwards – habitats that act as <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2004GL021009">sources of methane, a greenhouse gas</a>. This amplified global warming further and helped end the ice age.</p>
<p>The rate at which today’s climate is changing is unprecedented in the geological record, but our study shows how sensitive the Indian summer monsoon was during a global transition into warming in the past and may still be.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/264393/original/file-20190318-28483-e4zcsh.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/264393/original/file-20190318-28483-e4zcsh.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/264393/original/file-20190318-28483-e4zcsh.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=163&fit=crop&dpr=1 600w, https://images.theconversation.com/files/264393/original/file-20190318-28483-e4zcsh.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=163&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/264393/original/file-20190318-28483-e4zcsh.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=163&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/264393/original/file-20190318-28483-e4zcsh.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=205&fit=crop&dpr=1 754w, https://images.theconversation.com/files/264393/original/file-20190318-28483-e4zcsh.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=205&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/264393/original/file-20190318-28483-e4zcsh.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=205&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 same view in Maharashtra, India on August 28 2010, during the monsoon season.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/File:MatheranPanoramaPointMonsoon.JPG">Arne Hückelheim/Wikipedia</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>The monsoon rains of yesteryear</h2>
<p>Over the last one million years, the climate fluctuated between a cold glacial – known as an ice age – and a warm interglacial as the Earth’s position relative to the sun <a href="http://ossfoundation.us/projects/environment/global-warming/milankovitch-cycles">wobbled in its orbit</a>. The last transition from an ice age into the warm climate of the present interglacial – known as the Holocene – occurred around 18,000 years ago. This period of Earth’s history is relatively well understood, but how Earth system processes responded to these climate changes deeper in time is <a href="https://www.ipcc.ch/site/assets/uploads/sites/2/2019/02/SR15_Chapter3_Low_Res.pdf">still something of a mystery</a>.</p>
<p>A recent expedition to <a href="https://iodp.tamu.edu/scienceops/expeditions/indian_monsoon.html">drill deep into the ocean floor</a> of the Bay of Bengal gave an opportunity to reconstruct past Indian monsoon behaviour over hundreds of years before the last ice age.</p>
<p>Our study used these deep sea sediments from the northern Bay of Bengal to capture a direct signal of the Indian summer monsoon from 140,000 to 128,000 years ago, hidden in the fossilised shells of tiny microscopic creatures called foraminifera. These plankton species once lived in the upper ocean water column and captured the environmental conditions of the surrounding seawater in the chemical make up of their shells.</p>
<p>We detected the ocean surface water freshening from river discharge induced by the rains of the Indian summer monsoon from 140,000 to 128,000 years ago – a sign of the strengthening monsoon system. This occurred when the Earth was coming out of a glacial state and into the interglacial which occurred before the one we live in, separated by a single ice age. During this period – which we’ll refer to as the penultimate deglaciation – <a href="http://science.sciencemag.org/content/349/6244/aaa4019">sea levels rose</a> from six to nine metres worldwide.</p>
<p>Ice-core records show that Antarctica began to <a href="http://science.sciencemag.org/content/317/5839/793">warm first during the penultimate deglaciation</a>. Southern Hemisphere warming provided a source of heat and moisture which fuelled the strengthening of the Indian summer monsoon, as seen in our records of surface freshening and river runoff from the northern Bay of Bengal.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/264398/original/file-20190318-28496-1w7uxrb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/264398/original/file-20190318-28496-1w7uxrb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/264398/original/file-20190318-28496-1w7uxrb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/264398/original/file-20190318-28496-1w7uxrb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/264398/original/file-20190318-28496-1w7uxrb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/264398/original/file-20190318-28496-1w7uxrb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/264398/original/file-20190318-28496-1w7uxrb.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">Wetland in Leh Ladakh, India. The expansion of tropical wetlands further north released more methane to the atmosphere, accelerating global warming.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/swamp-green-field-blue-sky-summer-535948285">WATHIT H/Shutterstock</a></span>
</figcaption>
</figure>
<p>During this warming period around 130,000 years ago, the Indian summer monsoon responded to southern hemisphere warming while the northern hemisphere and other monsoon systems, such as the East Asian summer monsoon – which affects modern day China, Japan and the Far East – remained in a glacial state.</p>
<p>The Indian summer monsoon pulled heat and moisture northwards, driving glacial melting in the northern hemisphere and helping tropical wetlands expand their range. These expanding tropical wetlands resulted in more methane release into the atmosphere which <a href="https://www.nature.com/articles/nature06950">caused even more warming</a>, setting changes in motion which ended the global ice age.</p>
<p>The Indian summer monsoon is an incredibly dynamic system. Though confined to the tropics, the system is sensitive to climatic conditions in both hemispheres. Due to its role in contributing to methane emissions, the Indian summer monsoon also has an outsize impact on the global climate. Monsoons should not be viewed in isolation, just as the polar ice sheets shouldn’t. Earth’s internal climate system is intrinsically linked and abrupt changes at one place can have significant consequences over time elsewhere.</p>
<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">
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<span class="caption"></span>
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<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=Imagineheader1113504">Climate change is inevitable. Our response to it isn’t. Click here to subscribe to our climate action newsletter.</a></em></p><img src="https://counter.theconversation.com/content/113504/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Katrina Nilsson-Kerr receives funding from CENTA NERC. </span></em></p><p class="fine-print"><em><span>Pallavi Anand receives funding from NERC, UK-IODP and Cushman Foundation. </span></em></p>The Indian summer monsoon rainfall affects the lives of over a billion people. By looking at how prehistoric climate changes affected it, scientists can contribute to its future prediction.Katrina Nilsson-Kerr, PhD Researcher in Climatology, The Open UniversityPallavi Anand, Lecturer in Ocean Biogeochemistry, The Open UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1113452019-02-10T19:14:11Z2019-02-10T19:14:11ZMelting Himalayan glaciers: a big drop in a bucket that’s already full<p>A <a href="https://link.springer.com/book/10.1007%2F978-3-319-92288-1">new report</a> has warned that even if global warming is held at 1.5°C, we will still lose a third of the glaciers in the Hindu Kush-Himalaya (HKH) region. What does that mean for rivers that flow down these mountains, and the people who depend on them? </p>
<p>The HKH region is home to the tallest mountains on Earth, and also to the source of rivers that sustain close to 2 billion people. These rivers supply agriculture with water and with sediments that fertilise soils in valleys and the floodplain. </p>
<p>Some of these rivers are hugely culturally significant. The Ganges (or Ganga), for instance, which flows for more than 2,525km from the western Himalayas into the Bay of Bengal, is personified in Hinduism as the goddess Gaṅgā. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/257843/original/file-20190207-174857-jk1rf2.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/257843/original/file-20190207-174857-jk1rf2.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/257843/original/file-20190207-174857-jk1rf2.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/257843/original/file-20190207-174857-jk1rf2.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/257843/original/file-20190207-174857-jk1rf2.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/257843/original/file-20190207-174857-jk1rf2.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/257843/original/file-20190207-174857-jk1rf2.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">The Ganga River at Rishikesh, as it exits the Himalayas.</span>
<span class="attribution"><span class="source">Anthony Dosseto</span></span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/warm-ice-in-mount-everests-glaciers-makes-them-more-sensitive-to-climate-change-new-research-107325">Warm ice in Mount Everest's glaciers makes them more sensitive to climate change – new research</a>
</strong>
</em>
</p>
<hr>
<h2>When it rains, it pours… literally</h2>
<p>Before we get to the effect of melting glaciers on Himalayan rivers, we need to understand where they get their water.</p>
<p>For much of Himalayas, rain falls mostly during the monsoon active between June and September. The monsoon brings heavy rain and often causes <a href="https://www.youtube.com/watch?time_continue=99&v=QxoMqrjzM5E">devastating floods</a>, such as in <a href="https://www.theguardian.com/world/2013/jun/24/india-uttarakhand-floods-rescue-death-toll">northern India in 2013</a>, which forced the evacuation of more than 110,000 people.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/SjGGjywq8Fo?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">2013 floods in Uttarakhand, India.</span></figcaption>
</figure>
<p>But the summer monsoon is not the only culprit for devastating floods. Landslides can dam the river, and when this dam bursts it can cause dramatic, unpredictable flooding. Some of those events have been linked to folk stories of floods in <a href="https://theconversation.com/geomythology-can-geologists-relate-ancient-stories-of-great-floods-to-real-events-63434">many cultures around the world</a>. In the Himalayas, a <a href="https://www.sciencedirect.com/science/article/abs/pii/S0277379113002874">study</a> tracking the 1,000-year history of large floods showed that heavy rainfall and landslide-dam burst are the main causes.</p>
<p>When they melt, glaciers can also create natural dams, which can then burst and send floods down the valley. In this way, the newly forecast melting poses an acute threat.</p>
<p>The potential problem is worsened still further by the Intergovernmental Panel on Climate Change’s <a href="https://www.ipcc.ch/report/managing-the-risks-of-extreme-events-and-disasters-to-advance-climate-change-adaptation">prediction</a> that the frequency of extreme rainfall events will also increase.</p>
<h2>Come hell or high water</h2>
<p>What will happen to Himalayan rivers when the taps are turned to high in this way? To answer this, we need to look into the past. </p>
<p>For tens of thousands of years, rivers have polished rocks and laid down sediments in the lower valleys of the mountain range. These sediments and rocks tell us the story of how the river behaves when the tap opens or closes.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/257845/original/file-20190207-174894-ksaduy.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/257845/original/file-20190207-174894-ksaduy.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/257845/original/file-20190207-174894-ksaduy.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/257845/original/file-20190207-174894-ksaduy.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/257845/original/file-20190207-174894-ksaduy.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/257845/original/file-20190207-174894-ksaduy.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/257845/original/file-20190207-174894-ksaduy.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">Rock surfaces tell us where the river was carving into its bed.</span>
<span class="attribution"><span class="source">Anthony Dosseto</span></span>
</figcaption>
</figure>
<p>Some experts <a href="https://pubs.geoscienceworld.org/gsa/geology/article-abstract/30/10/911/192283/impulsive-alluviation-during-early-holocene">propose</a> that intense rain tends to trigger landslides, choking the river with sediments which are then dumped in the valleys. Others <a href="https://www.sciencedirect.com/science/article/abs/pii/S027737911000168X">suggest</a> that the supply of sediments to the river generally doesn’t change much even in extreme rainfall events, and that the main effect of the extra flow is that the river erodes further into its bed.</p>
<p>The <a href="https://www.sciencedirect.com/science/article/abs/pii/S0277379118300325">most recent work</a> supports the latter theory. It found that 25,000-35,000 years ago, when the monsoon was much weaker than today, sediments were filling up Himalayan valleys. But more recently (3,000-6,000 years ago), rock surfaces were exposed during a period of strong monsoon, illustrating how the river carved into its bed in response to higher rainfall.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/257846/original/file-20190207-174870-3o7iha.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/257846/original/file-20190207-174870-3o7iha.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/257846/original/file-20190207-174870-3o7iha.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/257846/original/file-20190207-174870-3o7iha.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/257846/original/file-20190207-174870-3o7iha.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/257846/original/file-20190207-174870-3o7iha.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/257846/original/file-20190207-174870-3o7iha.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">Sediments laid down in Himalayan valleys support agriculture, but also tell us the ancient story of rivers that carried them.</span>
<span class="attribution"><span class="source">Anthony Dosseto</span></span>
</figcaption>
</figure>
<p>So what does the past tell us about the future of Himalayan rivers? More frequent extreme rainfall events mean more floods, of course. But a stronger monsoon also means rivers will cut deeper into their beds, instead of fertilising Himalayan valleys and the <a href="https://en.wikipedia.org/wiki/Indo-Gangetic_Plain">Indo-Gangetic plain</a> with sediments.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/devastating-himalayan-floods-are-made-worse-by-an-international-blame-game-83103">Devastating Himalayan floods are made worse by an international blame game</a>
</strong>
</em>
</p>
<hr>
<p>What about glaciers melting? For as long as there are glaciers, this will increase the amount of meltwater in the rivers each spring (until 2060, according the <a href="https://link.springer.com/book/10.1007%2F978-3-319-92288-1">report</a>, after which there won’t be any meltwater to talk about). So this too will contribute to rivers carving into their beds instead of distributing sediments. It will also increase the risk of flooding from outburst of glacial lake dams.</p>
<p>So what is at stake? The melting glaciers? No. Given thousands or millions of years, it seems likely that they will one day return. But on a more meaningful human timescale, what is really at stake is us – our own survival. Global warming is reducing our resources, and making life more perilous along the way. The rivers of the Himalayas are just one more example.</p><img src="https://counter.theconversation.com/content/111345/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Anthony Dosseto receives funding from the Australian Research Council.</span></em></p>A new report predicts that one-third of the ice in the Himalayas will melt, even if we contain global warming to 1.5C. So what does that mean for the flood-prone valleys below?Anthony Dosseto, Associate Professor, University of WollongongLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1020062018-08-24T10:23:32Z2018-08-24T10:23:32ZWhy it’s so hard to detect the fingerprints of global warming on monsoon rains<figure><img src="https://images.theconversation.com/files/233260/original/file-20180823-149478-1piuumq.jpg?ixlib=rb-1.1.0&rect=15%2C426%2C5160%2C2716&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption"></span> <span class="attribution"><span class="source">AJP / shutterstock</span></span></figcaption></figure><p>The devastating floods in the Indian state of Kerala are a stark reminder of the vulnerability of the world’s most densely populated regions to weather and climate phenomena. In addition to the tragic loss of several hundred lives, widespread floods driven by unusually high and persistent monsoon rains have severely impacted the region’s fragile infrastructure and displaced more than a million people. Only in recent days has the Indian government been able to understand the full extent of an <a href="https://www.theguardian.com/world/2018/aug/21/kerala-india-more-than-1m-people-flee-to-relief-camps-to-escape-floods">estimated US$3 billion worth of damage</a>.</p>
<p>It is now typical that the aftermath of severe weather events is marked by questions about the role played by human-induced climate change. More precisely, scientists aim to provide a timely statement about the extent to which global warming has changed the likelihood of a certain weather-related hazard. The practice of attributing an event to climate change has become a regular activity and is being tackled with a growing number of methodologies.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1031169993587617792"}"></div></p>
<p>Improvements in the computer models used to make climate predictions means that attribution information can often be made available immediately after, and sometimes even during, the event. For instance, reports declaring this summer’s heatwave across Northern Europe to be <a href="https://www.worldweatherattribution.org/attribution-of-the-2018-heat-in-northern-europe/">at least twice as likely as a result of climate change</a> were circulated while many citizens continued to experience the scorching temperatures. Being able to communicate this information while the event is still firmly in the consciousness of the general public is potentially very powerful in changing the opinions of those resistant to climate action</p>
<h2>Effects on rainfall</h2>
<p>News of the worsening situation in Kerala is an opportunity to consider why understanding the effect of climate change is more difficult for some events than for others. For example, the links between global warming and temperature extremes are reasonably well understood. It should come as little surprise that a warmer world will bring more severe summer heatwaves and more frequent mild winters. When it comes to rainfall, however, things are a bit more complicated. </p>
<p>Unlike temperature, rainfall varies hugely in space and time. Even the most sophisticated climate models struggle to simulate physical processes such as convection and evaporation that drive rainfall activity. On top of that, global warming is not expected to change the frequency and intensity of rainfall extremes in the same way in all parts of the world.</p>
<p>On a global scale, an increase in the most severe rainfall events is anticipated given the atmosphere’s capacity to hold around 7% more water per °C rise in temperature, as described by the <a href="http://www2.ohlone.edu/people/jklent/labs/101a_labs/clausius-clapeyron.pdf">Clausius–Clapeyron relation</a>. But when we get to the regional scale, this relationship becomes somewhat distorted by the response of rainfall to meteorological phenomena such as tropical cyclones, thunderstorms and, in the case of the Kerala event, monsoons.</p>
<p>So, how should an extreme rainfall event be defined? By the amount of rain that fell or by the weather patterns that caused it?</p>
<p>The choice to focus solely on the rainfall itself is particularly relevant for flooding events. Though accusations of <a href="https://www.bbc.co.uk/news/world-asia-india-45243868">poor decision-making and mismanagement of water resources</a> are beginning to appear in the Kerala aftermath, the floods simply would not have occurred without a significant amount of rain. Few of those suffering lost homes and livelihoods are likely to care much about where the rain came from or the intricacies of the weather conditions that led to it.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1029322875034103809"}"></div></p>
<p>But to understand as much as possible we must consider the individual responses of weather phenomena to a changing climate. Different approaches tackle the problem in different ways – and may produce conflicting results. Even in the absence of a significant trend in the highest rainfall totals, a climate change signature may still exist in the form of rising temperatures in the oceans where the moisture that fed the rainfall originated.</p>
<p>Disentangling these contributory factors takes time. In comparison to droughts and heatwaves, short-term hazards such as floods do not usually give us much chance to report concrete findings while the media and general public are still engaged in the event. In-depth studies may not publish their results for many months, sometimes even years after the event in question.</p>
<p>Many of these issues are not exclusive to extreme rainfall. The excellent US National Academies report on <a href="https://www.nap.edu/read/21852">Attribution of Extreme Weather Events in the Context of Climate Change</a> describes the shortcomings in our efforts to attribute a variety of extremes. But for rainfall in particular there is a discrepancy between what we understand about the general effect of global warming and our rather lesser ability to quantify the climate change fingerprint on specific events. </p>
<p>While this is a cause for concern, the opportunity for improvement should be the focus of our attempts to make attribution a more effective vehicle for communicating climate risk.</p><img src="https://counter.theconversation.com/content/102006/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jonathan Eden has worked on projects funded by the UK's Natural Environment Research Council (NERC), the European Commission and the Volkswagen Foundation. He is a member of the Open Network of the India-UK Water Centre (IUKWC) jointly funded by the Indian Ministry of Earth Sciences (MoES) and NERC.</span></em></p>Kerala floods show the relationship between climate change and extreme rainfall is complex.Jonathan Eden, Research Fellow in Climate Variability and Hydrological Change, Coventry UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1018832018-08-23T13:14:05Z2018-08-23T13:14:05ZKerala’s monsoon: lessons from recent floods in India<p>Media call it the <a href="https://www.wsj.com/articles/floods-wash-over-southern-india-displacing-800-000-1534673105">worst flood of the century</a> in the region. After more than two weeks of relentless rain, Kerala, a state at the southern tip of India, known internationally for its scenic green landscapes, touristic spots and backwaters, is left with over 1 million people in relief camps, and close to 400 reported dead – the number is expected to be much higher, as many areas <a href="https://scroll.in/article/891317/in-keralas-attappady-relief-workers-struggle-to-reach-adivasis-in-remote-forest-areas">remain inaccessible</a>.</p>
<p>In the mountainous Coorg or Kodagu district in the neighbouring state of Karnataka, thousands of people have been marooned because of torrential rains. Exacerbated by landslides in hilly terrain, flooding has led to the destruction of homes, bridges, road networks and industries.</p>
<p>Far from being a surprise, the possibility of such devastation was highlighted several years ago.</p>
<h2>The need to change our development approach</h2>
<p>In 2011, the Western Ghats Ecology Expert Panel, chaired by the internationally renowned ecologist Madhav Gadgil, submitted <a href="http://www.moef.nic.in/downloads/public-information/wg-23052012.pdf">a report</a> to the Indian Ministry of Environment and Forests. The report warned that an ill-thought focus on development was impacting the sustainability of the Western Ghats hill chain, one of the world’s most biodiverse areas that runs along the west coast of India. The expert report urged a number of states, including Karnataka and Kerala, to adopt an approach of thoughtful conservation, limiting activities such as quarrying, dams and construction near protected forests in hilly areas. The <a href="https://www.indiatoday.in/kerala-floods/story/kerala-floods-is-man-made-calamity-madhav-gadgil-1316713-2018-08-17">report was rejected</a> by the Ministry as well as by both states.</p>
<p>With the experience of hindsight, it is clear that the worst flood damage took place in those regions where the Gadgil committee recommended protection.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/PaDiU7xQKj8?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">The Nasa released the video of Kerala in South India hit by heavy rainfall.</span></figcaption>
</figure>
<p>In Kodagu, for instance, <a href="https://bangaloremirror.indiatimes.com/bangalore/cover-story/power-grid-corporation-of-india-nought-axe-green-activists-central-power-research-institute-indian-institute-of-science-dasara-elephant/articleshow/43742645.cms">tens to hundreds of thousands of large trees were felled</a> in 2015 to construct a high-tension electric wire line. Uncontrolled sand mining has constrained river flows, while the rapid spread of high-rise buildings on unstable hill slopes has weakened the soil. This unplanned development has left the area susceptible to flash floods and landslides, caused by a combination of tree felling on steep hillslopes and heavy rainfall.</p>
<h2>Airports built on water bodies</h2>
<p>The flooding of the Kochi airport is another example of poor planning leading to disastrous outcomes. The airport was built on the paddy fields and wetlands adjacent to the Periyar river, and extends up to the banks of the river on one side.</p>
<p>The longest river in Kerala, it has a number of dams – some of which had to be opened to release water during the rains. The airport was badly hit, with estimated economic costs of <a href="https://www.thehindu.com/news/national/kerala/kerala-rains-floods-and-flood-relief-operations-live-updates/article24734795.ece">at least Rs 500 crores</a> because of its forced closure for several days.</p>
<p>The Periyar river is not the only one that has been dammed. The state of Kerala has 44 rivers with a total of 61 dams. Many had to be opened across Kerala as they were dangerously full – a step that, while essential during a time of emergency, contributed to the heavy flooding. A 2017 report by the Comptroller and Auditor General of India warned that <a href="https://www.downtoearth.org.in/news/natural-disasters/kerala-floods-what-to-expect-when-none-of-the-61-dams-have-any-emergency-plan--61416">not a single one of these dams</a> had an emergency action plan in place for disaster management. Pre- and post-monsoon safety inspections <a href="https://cag.gov.in/sites/default/files/audit_report_files/Report_No.10_of_2017_-_Performance_audit_Union_Government_Schemes_for_Flood_Control_and_Flood_Forecasting_Reports_of_Ministry_of_Water_Resources%2C_River_Development_%26_Ganga_Rejuven.pdf">had not been carried out</a> for any of these dams either.</p>
<p>Given how likely it is that coastal and riverine cities will experience flooding in coming years, you would think we know better than to build <a href="https://timesofindia.indiatimes.com/india/Airports-on-lakes-runways-on-rivers/articleshow/50114922.cms">airports near bodies of water</a>. Yet Kochi airport is not an exception. The runways of the Mumbai airport have been built over the Mithi river, and the airport is located on a reclaimed pond. One of the runways of the Chennai airport extends over the Adyar river, <a href="https://www.thenewsminute.com/article/warnings-not-build-runway-over-adyar-river-ignored-that%E2%80%99s-why-chennai-airport-sunk-36664">affecting its long-term safety and stability</a>.</p>
<p>It is no surprise that these airports, which are among the busiest in India, frequently flood when the rains are heavy – leading to large-scale economic losses. Yet the new Navi Mumbai airport is coming up in an equally unsuitable location on coastal wetlands.</p>
<h2>Reversing the trend</h2>
<p>In the era of climate change we have just entered, extreme rainfall events are going to become increasingly common. Uncontrolled growth at the expense of the environment will severely exacerbate the impacts of climate change. Our cities are simply not prepared for extreme weather events. The recent <a href="https://www.standard.co.uk/news/world/genoa-bridge-collapse-22-dead-as-morandi-bridge-in-italy-crumbles-in-torrential-rainfall-a3911131.html">collapse of a bridge in Genoa</a>, killing at least 43 people, is linked to poor maintenance, but also to heavy rainfall.</p>
<p>Certain types of infrastructure may be less suitable to some contexts in a changing climate scenario. Wildfires in California <a href="https://theconversation.com/wildfires-are-inevitable-increasing-home-losses-fatalities-and-costs-are-not-101295">cause extensive damage to private property</a> because many cities are extending their boundaries into forest areas. As local climate becomes hotter and drier, with fires becoming more likely, new homes are being built in areas that are highly susceptible to fire instead of less exposed locations.</p>
<p>Some cities are seeking to reverse this trajectory of unplanned construction. Nairobi is in the midst of <a href="https://www.nation.co.ke/counties/nairobi/Dozens-of-structures-demolished-in-Nairobi-/1954174-4723042-4ym8l0z/index.html">an extensive demolition drive</a>, uprooting thousands of buildings built on riparian land that choke the flow of water and contribute to severe annual floods.</p>
<p>In Seoul, between 2002-2005, the city municipality tore up an elevated highway that had been built over the <a href="https://inhabitat.com/how-the-cheonggyecheon-river-urban-design-restored-the-green-heart-of-seoul/">Cheonggyecheon stream</a>. This internationally famous urban-renewal project reduced traffic, reduced air pollution and cut the urban heat-island effect. In Yonkers, New York, an ongoing project aims to restore the buried <a href="https://ny.curbed.com/2016/12/15/13963898/yonkers-saw-mill-river-photo-essay">Saw Mill river</a>.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/233249/original/file-20180823-149493-wnzmmo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/233249/original/file-20180823-149493-wnzmmo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/233249/original/file-20180823-149493-wnzmmo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/233249/original/file-20180823-149493-wnzmmo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/233249/original/file-20180823-149493-wnzmmo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/233249/original/file-20180823-149493-wnzmmo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/233249/original/file-20180823-149493-wnzmmo.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">Millions of dollars have been invested to rehabilitate the Saw Mill River in the state of New York and bring nature back in the city, August 2016.</span>
<span class="attribution"><a class="source" href="https://upload.wikimedia.org/wikipedia/commons/e/ec/Saw_Mill_River_east_daylight_2016_jeh.jpg">Jim Henderson/Wikimedia</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span>
</figcaption>
</figure>
<p>Similar urban river daylighting projects are <a href="https://www.thenatureofcities.com/2015/03/17/daylighting-and-restoring-urban-streams-ponds-and-wetlands-can-provide-huge-ecological-and-social-benefits-are-such-restorations-worth-it-what-are-the-pitfalls-how-can-we-demonstrate-these-ben/">gaining traction</a> in cities around the world. Zurich has been an early pioneer, developing the <a href="http://eprints.whiterose.ac.uk/75871/7/Captured_Streams_and_Springs_in_Combined_Sewers_Broadhead_wr.pdf"><em>Bachkonzept</em> (stream concept)</a> to create, restore and uncover a number of streams and springs. London, which built over a number of famous rivers, has <a href="https://www.weforum.org/agenda/2017/09/daylighting-is-a-new-trend-that-s-transforming-cities/">now uncovered and restored a number of these waterways</a>, while Sheffield, having experimented with daylighting, is now considering <a href="https://www.theguardian.com/cities/2017/aug/29/river-runs-global-movement-daylight-urban-rivers">uncovering sections of the local Sheaf river</a>.</p>
<p>The demonstrated ecological and environmental benefits are clear – as are the social and economic returns. For example, Seoul’s iconic Cheonggyecheon stream restoration led to a more than six-fold increase in biodiversity, a 35% decrease in air pollution and a growth in property prices that is <a href="https://landscapeperformance.org/case-study-briefs/cheonggyecheon-stream-restoration">double of that in other parts of the city</a>.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/233252/original/file-20180823-149475-llmzse.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/233252/original/file-20180823-149475-llmzse.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=398&fit=crop&dpr=1 600w, https://images.theconversation.com/files/233252/original/file-20180823-149475-llmzse.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=398&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/233252/original/file-20180823-149475-llmzse.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=398&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/233252/original/file-20180823-149475-llmzse.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=500&fit=crop&dpr=1 754w, https://images.theconversation.com/files/233252/original/file-20180823-149475-llmzse.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=500&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/233252/original/file-20180823-149475-llmzse.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">Investment in the Cheonggyecheon stream is amply repaid many times over in economic security and growth, local health and quality of life.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/rinux/57115188/in/photolist-63JmC-63JAT-63JnL-63JBn-63Jp2-63K7p-63K6U-63JWc-46rwwR-82cRuj-63Jax-63Jbq-63JVv-4RQBvi-bzfj9h-4VP3nf-bX4SC7-odymKg-odymFZ-pVTjGV-nWn4Ji-dsmiLU-c9S8nW-7K2Z6B-Wb5HQ8-bzfiWU-7udJGX-eHRKw6-dSuq7d-jmvq1P-pVUEvD-bN9Yda-qJnd7U-6oXCHh-oNDkxj-pchXk2-KDWkCg-WqvgYm-7K6U8o-dsm9N4-dsm8Zi-bzfi3Y-nWnXcr-4VNZgJ-np69DQ-7utmsx-dsm976-c1GdZw-dsm9Wn-npnqWa">riNux/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>The restored stream attracts tens of thousands of visitors daily who contribute significantly to local economy. Such ideas of restoration need to become more widespread, and embedded in routine climate change and disaster management planning. The investment made is amply repaid many times over in economic security and growth, biodiversity, local health and quality of life, and resilience against future disasters.</p>
<p>Once the emergency relief is attended to, Kochi and Kodagu would do well to use their recent experience as a warning of future disasters to come in a world of increasingly uncertain climate.</p>
<p>The focus must be on long-term restoration projects that can reverse some of the environmental and ecological damage that has led to the current situation. But such learning need not be confined to the areas that have experienced the worst. The rest of the world has much to learn as well.</p><img src="https://counter.theconversation.com/content/101883/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Harini Nagendra ne travaille pas, ne conseille pas, ne possède pas de parts, ne reçoit pas de fonds d'une organisation qui pourrait tirer profit de cet article, et n'a déclaré aucune autre affiliation que son organisme de recherche.</span></em></p>Uncontrolled growth at the expense of the environment will severely exacerbate the impacts of climate change. As shown with tragic floods in India, our cities are not prepared for extreme events.Harini Nagendra, Professor of Sustainability, Azim Premji UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/899492018-01-11T15:19:54Z2018-01-11T15:19:54ZWill the weather get worse in 2018? What the experts say<figure><img src="https://images.theconversation.com/files/201626/original/file-20180111-60744-hwry45.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="http://www.epa.eu/disasters-photos/fire-photos/thomas-fire-burns-in-los-padres-national-forest-photos-53949696">EPA</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>Last year unleashed some catastrophic weather across the world. At the beginning of 2017, Australia experienced one of the <a href="http://www.bbc.co.uk/news/world-australia-39175668">hottest summers on record</a> in Sydney and Brisbane, followed by a killer <a href="https://www.theguardian.com/world/2017/aug/04/extreme-heat-warnings-issued-europe-temperatures-pass-40c">summer heatwave</a> across southern Europe and <a href="http://edition.cnn.com/2017/12/11/us/california-wildfires/index.html">wildfires</a> triggered by heat in California.</p>
<p>The Atlantic hurricane season was particularly active, recording three mighty category 5 hurricanes – <a href="https://www.theguardian.com/us-news/2017/dec/13/global-warming-made-hurricane-harvey-deadly-rains-three-times-more-likely-research-shows">Harvey</a>, <a href="http://edition.cnn.com/specials/hurricane-irma">Irma</a> and <a href="http://edition.cnn.com/specials/weather/hurricane-maria">Maria</a> – resulting in significant casualties. The cost of the damage across the American continent was in excess of <a href="http://www.bbc.co.uk/news/science-environment-42608161">$260 billion</a>.</p>
<p>At the same time, the 2017 monsoon season brought considerable rains to the Indian subcontinent, and resulted in <a href="https://www.theguardian.com/world/2017/aug/30/mumbai-paralysed-by-floods-as-india-and-region-hit-by-worst-monsoon-rains-in-years">devastating floods</a> in parts of India, Pakistan, Nepal and Bangladesh (one of the most flood vulnerable countries in the world), causing more than 1,000 deaths.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/201627/original/file-20180111-60756-1rpzitx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/201627/original/file-20180111-60756-1rpzitx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=398&fit=crop&dpr=1 600w, https://images.theconversation.com/files/201627/original/file-20180111-60756-1rpzitx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=398&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/201627/original/file-20180111-60756-1rpzitx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=398&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/201627/original/file-20180111-60756-1rpzitx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=500&fit=crop&dpr=1 754w, https://images.theconversation.com/files/201627/original/file-20180111-60756-1rpzitx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=500&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/201627/original/file-20180111-60756-1rpzitx.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">Monsoon flooding in the Himalayan foothills of India, Bangladesh and Nepal affected more than 40m people last year.</span>
<span class="attribution"><a class="source" href="http://www.epa.eu/disasters-photos/flood-photos/floods-in-india-photos-53745858">EPA</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>At the end of 2017, we could look back at the statistics and see that globally it was the warmest <a href="https://www.metoffice.gov.uk/learning/learn-about-the-weather/what-is-el-nino-la-nina">non-El Nino</a> year on record. El-Nino is the warming part of the <a href="https://www.metoffice.gov.uk/learning/learn-about-the-weather/what-is-el-nino-la-nina">El-Nino Southern Oscillation</a> (ENSO) cycle which affects global ocean and atmospheric currents and can create powerful storms and hurricanes.</p>
<p>In a world that is getting warmer, what does that mean and what might 2018 hold for weather across the globe? Are we destined to see more and more of these “unusual” and catastrophic weather events which result in significant devastation? What effect will climate change have on our weather and will this become the new norm? </p>
<h2>Looking at the facts</h2>
<p>First, we need to untangle the <a href="https://www.nasa.gov/mission_pages/noaa-n/climate/climate_weather.html">difference</a> between weather and climate change, something president Trump seems <a href="http://edition.cnn.com/2017/12/28/politics/trump-climate-change-analysis/index.html">to confuse</a>. In a nutshell, the difference is time. Weather is the conditions in the atmosphere over a short period of time. Climate is how the atmosphere behaves over a longer period of time. When we talk about climate change, that generally means changes in long-term averages of daily levels of temperature and rainfall. So we may see a change in average or typical weather over a number of years, but we can still experience extremes in any one year. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/ZTxRInrS17c?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">YouTube/CNN.</span></figcaption>
</figure>
<p>Recently, scientists have used <a href="https://www.munichre.com/topics-online/en/2017/topics-geo/rapid-attribution">robust event attribution</a> where natural or human influences on particular events are studied to understand the role <a href="https://www.nasa.gov/audience/forstudents/5-8/features/nasa-knows/what-is-climate-change-58.html">climate change</a> may play in particular weather events. This can help support future regional contingency planning.</p>
<p>This also helps us to understand the role climate change has played in past events such as heatwaves, wildfires, droughts, or extreme flooding and some of their large-scale drivers such as ocean and atmospheric patterns of warming and cooling, like El-Nino.</p>
<p>Looking at the past there are many factors which control the onset, spread and eventual impact of a big weather event. But not all of these factors are climatic and many relate to things such as urbanisation, engineering interventions or land-use changes.</p>
<h2>What the future looks like</h2>
<p>According to the Intergovernmental Panel on Climate Change <a href="http://www.ipcc.ch/">IPCC</a>, an international body set up to assess the science of climate change, we can continue to expect <a href="https://climate.nasa.gov/vital-signs/global-temperature/">an increase</a> in the average global temperature. That means we will be experiencing warmer years in the future. </p>
<p>But at the same time, we may see changes to the extremes, which could become more frequent in the case of high temperature or heavy rainfall, or less frequent in the case of extreme cold. This means that the distribution, occurrence and expected averages of our weather (for example, temperature and rain) throughout the year may change, resulting in warmer years on average with more extreme hot days, and fewer extreme cold days in the future.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/201632/original/file-20180111-60756-13wet95.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/201632/original/file-20180111-60756-13wet95.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/201632/original/file-20180111-60756-13wet95.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/201632/original/file-20180111-60756-13wet95.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/201632/original/file-20180111-60756-13wet95.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/201632/original/file-20180111-60756-13wet95.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/201632/original/file-20180111-60756-13wet95.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">Heavy snowfall on the US eastern seaboard seriously disrupted cities like New York this winter.</span>
<span class="attribution"><a class="source" href="http://www.epa.eu/weather-photos/weather-photos/late-season-snowstorm-hits-us-northeast-photos-53387532">EPA</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>This pattern has a direct link to such phenomena as heatwaves, which are caused by more extreme temperatures. The links to droughts or periods of extreme low flows in rivers are more complex. <a href="http://www.ipcc-data.org/guidelines/pages/gcm_guide.html">Global Circulation Models</a> (GCMs) – a collection of numerical models that provide a 3D analysis of global climate interactions such as atmosphere, oceans, ice and land – <a href="https://www.nature.com/articles/ncomms14196?utm_source=Daily+Carbon+Briefing&utm_campaign=fe1e50b881-cb_daily&utm_medium=email&utm_term=0_876aab4fd7-fe1e50b881-303473869">predict</a> increases in temperatures for some regions, such as southern Europe.</p>
<p>In terms of tropical cyclones, the effects of climate change on these phenomena is an active area of research as the processes are complex. For example, the <a href="https://www.britannica.com/science/Clausius-Clapeyron-equation">Clausius-Clapeyron</a> relationship which can be related to the water vapour-carrying capacity of the atmosphere, may have an impact on the strength and intensity of such storms.</p>
<p>The relationship states that for every degree rise in temperature, the water-holding capacity of the atmosphere increases by 7%, so in a warming ocean, the air above the water has a much greater capacity to hold water and thus store more rain that can feed more powerful storms.</p>
<p>But sinking cold air from the upper atmosphere may prevent storms from rising in the first place. If this happens more frequently with climate change then we can expect fewer such storms. That means in the future there may be fewer tropical cyclones forming, but those that do will be stronger and more intense.</p>
<h2>Wet wet wet</h2>
<p>In a warming world, we can expect it to get wetter. The distribution of the rainfall throughout the year could change as we experience longer, drier spells, although when rain falls it may be in intense bursts. Recent <a href="https://research.ncl.ac.uk/media/sites/researchwebsites/convex/CONVEX_downpours.pdf">research</a> by Newcastle University analysed the results from finer scale GCMs climate projections and suggests we may expect more intense summer rainfall in the UK in future. <a href="http://ukclimateprojections.metoffice.gov.uk/24125">New climate projections</a> from GCMs are being prepared for the UK to help predict what the future climate may look like. </p>
<p>Flooding from intense rainfall or river sources has many complex drivers which cause the damage in catchment areas. For example, land use changes (such as intensive farming practices or deforestation) and the degree of urbanisation both play a part in flood risk. Recent <a href="http://www.mdpi.com/2073-4441/9/2/103/htm">research</a> for the UK suggests that we will see an increase in the frequency of extreme river flooding.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/ai5mhuyaYwM?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">KSBY News/YouTube.</span></figcaption>
</figure>
<p>So what can we expect for 2018? Already Australia is experiencing <a href="https://www.nytimes.com/2018/01/07/world/australia/heat-wave.html?_r=0">extreme heat</a>, while the eastern seaboard of the US is suffering a <a href="https://www.vox.com/science-and-health/2018/1/3/16845048/winter-storm-2018-bomb-cyclone-blizzard-florida-new-york-boston-new-england">severe cold spell</a>, and the west coast <a href="http://edition.cnn.com/2018/01/11/us/southern-california-mudslides/index.html">devastating mudslides</a> that have killed 17 people. So far 2018 seems to be picking up right where 2017 left off.</p>
<p>Governments need to recognise and absorb that extreme weather across the globe is likely to become more common and start to adapt accordingly, rather than treat it as shocking one-off events. Otherwise we risk increasing loss of life and environmental damage in the future.</p><img src="https://counter.theconversation.com/content/89949/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Lindsay Beevers receives funding from the Engineering and Physical Sciences Research Council and the Natural Environment Research Council. </span></em></p>A survey of recent global trends in temperature and rainfall – and a lesson for Mr Trump on the difference between weather and climate.Lindsay Beevers, Professor/Chair Futures Forum, Heriot-Watt UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/833282017-09-01T14:31:00Z2017-09-01T14:31:00ZMumbai floods: what happens when cities sacrifice ecology for development<p>As the storm that was <a href="https://theconversation.com/dont-blame-climate-change-for-the-hurricane-harvey-disaster-blame-society-83163">hurricane Harvey</a> deluged the areas around Houston, Texas, large parts of <a href="https://theconversation.com/devastating-himalayan-floods-are-made-worse-by-an-international-blame-game-83103">northern India, Nepal and Bangladesh</a> also experienced heavy rains. </p>
<p><a href="https://www.theguardian.com/world/2017/aug/30/mumbai-paralysed-by-floods-as-india-and-region-hit-by-worst-monsoon-rains-in-years">And the city of Mumbai was hit by another major flooding espisode</a>. Several people have died in the city, many in the <a href="http://www.ndtv.com/mumbai-news/three-storey-building-collapses-in-mumbai-many-feared-trapped-1744236">collapse</a> of a four-storey building that is believed to have been weakened by the rains. </p>
<h2>Overcrowded cities</h2>
<p>Such loss of life in urban areas is often blamed on India’s overcrowding. Cities are growing at unprecedented rates. From a population of <a href="https://books.google.fr/books?id=BeDhBQAAQBAJ&pg=PA229&lpg=PA229&dq=2.86+million+in+1950+mumbai&source=bl&ots=jE4AOv3YZd&sig=a5U_2yZYiSq8T9WbSyCCis4Qigk&hl=en&sa=X&ved=0ahUKEwjV36D-zoHWAhXD0RQKHQXEC1YQ6AEIKDAA#v=onepage&q=2.86%20million%20in%201950%20mumbai&f=false">2.86 million in 1950</a>, Mumbai is now home to more than 21 million people, and is expected to have almost <a href="http://sites.uoit.ca/sustainabilitytoday/urban-and-energy-systems/Worlds-largest-cities/population-projections/city-population-2050.php">28 million by 2030</a>.</p>
<p>Built along the coastline on a series of islands, the city is surrounded by water: in mudflats, lakes, creeks, rivers, and the ever-present coastline. </p>
<p>Given the <a href="https://www.theguardian.com/cities/gallery/2015/apr/23/price-property-mumbai-in-pictures">astronomical land prices</a> in many parts of Mumbai, and the extreme scarcity of land, it is no surprise that Mumbai has sacrificed its ecology for development. Real estate projects, industry, and state infrastructure (railways, roads and the city’s airport) have built over, and choked, the city’s water networks at various strategic points. Every monsoon, the city floods. </p>
<p>Mudflats, wetlands, floodplains, mangroves and wooded vegetation <a href="https://www.nature.org/media/oceansandcoasts/mangroves-for-coastal-defence.pdf">once slowed down the flow of storm water</a>. The mangrove’s complex root systems and the branching architecture of trees acted as a natural barrier to reduce the force of water flow. But now, they are built over. Garbage spread everywhere clogs the waterways. Most channels and waterways that connect water bodies have been built over too, resulting preventing streams from easily reaching the sea – forcing it to spread out into the low lying areas of the city, adding to the severe flooding.</p>
<p>Mumbai’s extensive wetlands and mudflats, which had connected parts of the city <a href="https://books.google.fr/books?id=pWhx56mvzYYC&pg=PA135&lpg=PA135&dq=mumbai+history+mudflats&source=bl&ots=-Q7ArESbR7&sig=gcmD4tIO2lPB9pfyU3As0DPcFJI&hl=en&sa=X&ved=0ahUKEwiki6_FvYPWAhVNsBQKHfcOD704HhDoAQglMAA#v=onepage&q=mumbai%20history%20mudflats&f=false">since the early 19th century</a>, have disappeared. Their presence would retain the rain water and soak it into the ground, recharging the wells and ground water table. </p>
<p>Today, with nothing but concrete all around, the city’s land surface <a href="http://www.tandfonline.com/doi/abs/10.1080/01944369608975688">does not</a> allow water to soak into it. In especially intense periods of rain, the devastation is extreme – at least 5000 people are believed to have perished <a href="http://www.ndtv.com/photos/news/26july-2005-the-day-mumbai-stopped-11000">in the infamous floods of 2005</a>, and the economic damage was estimated at <a href="http://news.bbc.co.uk/1/hi/world/south_asia/4737187.stm">30 billion rupees (US$690m)</a>. </p>
<h2>The need for introspection</h2>
<p>After the 2005 floods, a committee constituted by the government investigated the reasons for the devastation, concluding that there was an urgent need to restore Mumbai’s wetlands and water systems. In 2007, the municipality <a href="http://www.alnap.org/resource/7180">formulated the Greater Mumbai Action Plan</a>, which among other efforts had a major focus on the restoration of the city’s main river, the Mithi, which had become little more <a href="http://www.hindustantimes.com/mumbai-news/mumbai-s-mithi-is-more-sewer-than-river-now/story-sQhm1HYzYvu6oTND6YS51J.html">than a sewage channel</a> in parts. </p>
<p>Yet around the same time, the chair of the committee overseeing the plan, <a href="http://pib.nic.in/newsite/PrintRelease.aspx?relid=161961">water expert Madhav Chitale</a> spoke publicly about the lack of progress in implementing its recommendations. He said that <a href="http://www.thehindubusinessline.com/todays-paper/tp-economy/chitale-committee-report/article1734744.ece">the city lacked basic topographic data</a> which were essential to build pathways for rainwater flow – which could have prevented flooding in subsequent rains. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/184231/original/file-20170831-22435-4feiod.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/184231/original/file-20170831-22435-4feiod.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=402&fit=crop&dpr=1 600w, https://images.theconversation.com/files/184231/original/file-20170831-22435-4feiod.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=402&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/184231/original/file-20170831-22435-4feiod.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=402&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/184231/original/file-20170831-22435-4feiod.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=505&fit=crop&dpr=1 754w, https://images.theconversation.com/files/184231/original/file-20170831-22435-4feiod.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=505&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/184231/original/file-20170831-22435-4feiod.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=505&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Malad creek, suburban Mumbai, 2010.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/ravikhemka/4588707292">Ravi Khemka/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>In recent years, climate scientists, urban specialists and civic society groups warned repeatedly that <a href="https://www.theguardian.com/cities/2014/nov/27/mumbai-flood-rain-monsoon-city-planning">Mumbai was heading for another heavy flood</a>. A combination of the greater likelihood of high rainfall events because of climate change, and an even more inadequately prepared city, created a situation ripe for a disaster in the making. These warnings came true this monsoon season. </p>
<p>Mumbai’s planners know that climate change is leading to increased likelihood of extreme rainfall, and that restoration of the city’s wetland, river and floodplain networks is central to flood control. Yet the rush to develop construction projections in the city has often disregarded these factors. <a href="http://www.thehindu.com/news/cities/bangalore/Money-can%E2%80%99t-replace-nature-in-cities/article15000625.ece">Money cannot replace nature in cities</a>. A careful reading of Indian urban history shows that <a href="https://youtu.be/Fz81-iunHu4">cities have historically grown with nature providing a support system</a>. When this system is eroded – as is seen in so many Indian cities today, including in Delhi, <a href="https://news.mongabay.com/2016/07/can-nature-thrive-in-cities/">Bangalore</a> and Chennai – the very survival of the city is placed in question.</p>
<p>The story of Mumbai today is a reflection of the ills that plague many Indian cities – and those in other parts of the world as well, such as Miami and Houston.
In a wetter future, it is clearer than ever that cities need ecology to grow.</p><img src="https://counter.theconversation.com/content/83328/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Harini Nagendra receives funding from Azim Premji University for her research on urban sustainability. </span></em></p>Flooding in India’s main financial hub is a reminder that urban growth has to work with nature.Harini Nagendra, Professor of Sustainability, Azim Premji UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/783722017-06-16T05:59:57Z2017-06-16T05:59:57ZIndia’s wells are running dry, fast<p><a href="http://www.livemint.com/Money/QeMGJQfsUTbVZy4ZETPUBN/Late-monsoon-rising-prices-may-further-delay-rate-cut-by-RB.html">Over the past three years</a>, the monsoon – the rainy season that runs from June through September, depending on the region – has been weak or delayed across much of India, causing widespread water shortages.</p>
<p>With the onset of summer this year, southern India, particularly Karnataka, Kerala and Tamil Nadu states, are already wilting under a blistering sun and repeated heatwaves. Drought is expected to affect at least <a href="http://economictimes.indiatimes.com/news/economy/policy/8-states-declared-drought-affected-centre-allows-them-to-offer-50-days-of-extra-work-under-nregs/articleshow/58037760.cms">eight states</a> in 2017, which is a devastating possibility in a country where <a href="http://data.worldbank.org/indicator/NV.AGR.TOTL.ZS">agriculture accounted for 17.5% of GDP in 2015</a> and provides the livelihood for nearly half the population. </p>
<p>Across rural India, water bodies, including man-made lakes and reservoirs, are fast disappearing after decades of neglect and pollution.</p>
<p>“They have drained out the water and converted the land into a plot for schools, dispensaries, and other construction activities,” Manoj Misra of the NGO Yamuna Jiye Abhiyan <a href="http://www.thehindu.com/news/cities/Delhi/water-bodies-disappearing-fast-in-rural-areas/article3823908.ece">warned in The Hindu newspaper</a> as far back as 2012.</p>
<h2>Not a drop to drink</h2>
<p>It wasn’t always this way. For the past 2,500 years, India has managed its water needs by <a href="http://www.indiawaterportal.org/sites/indiawaterportal.org/files/Waternama_english.pdf">increasing supply</a>. </p>
<p>Prior to industrialisation and the accompanying global “<a href="https://www.cabdirect.org/cabdirect/abstract/19926713240">green revolution</a>” in the 1960s, which saw the development of high-yield variety crops using new technologies, India’s water availability was plentiful. Households, industries and farmers freely extracted groundwater and dumped untreated waste into waterways without a second thought. </p>
<p>But such practices are now increasingly untenable in this rapidly growing country. Per capita availability of water has been steadily falling for over a decade, dropping <a href="http://pib.nic.in/newsite/PrintRelease.aspx?relid=119797">from 1,816 cubic metres per person in 2001 to 1,545 cubic metres in 2011</a>. </p>
<p>The decline is projected to deepen in coming years as the population grows. India, which currently has 1.3 billion people, is set to overtake China by 2022 and reach <a href="https://esa.un.org/unpd/wpp/publications/files/key_findings_wpp_2015.pdf">1.7 billion in 2050</a>. </p>
<p>Water scarcity is also exacerbated by a growth in water-intensive industries, such as thermal power production, extraction and mining, as India seeks to feed and power its growing population. In addition to affecting biodiversity, these activities also <a href="http://www.gaiafoundation.org/UnderMiningtheWaterCycle.pdf">alter natural water systems</a>. </p>
<p>Still, successive governments have pursued the same old supply-centric policies, paying little heed to the country’s waning clean water supplies. </p>
<p>For nearly 50 years, <a href="http://iopscience.iop.org/article/10.1088/1748-9326/11/8/084005">a misguided groundwater policy</a> has sucked India dry; water tables have declined by an average of <a href="https://www.nasa.gov/topics/earth/features/india_water.html">one metre every three years</a> in some parts of the Indus basin, turning it into the <a href="https://earthobservatory.nasa.gov/IOTD/view.php?id=86263">second most over-stressed aquifer in the world</a>, according to NASA.</p>
<p>Across nearly the whole country, basic sewage management is also lacking. According to the Third World Centre for Water Management, only about 10% of waste water in the country is <a href="https://thirdworldcentre.org/communication-media/urbanization-in-india/">collected and properly treated</a>. As a result, all water bodies in and around urban centres are seriously polluted. </p>
<p>Today, the country is struggling to provide safe drinking water to every citizen. </p>
<h2>What conservation?</h2>
<p>Even so, residents of New Delhi or Kolkata today use more than twice as much water, on average, than people in <a href="https://thirdworldcentre.org/communication-media/too-little-too-late-why-water-pricing-and-management-in-singapore-needs-to-be-more-ambitious/">Singapore, Leipzig, Barcelona or Zaragoza</a>, according to data compiled by the Third World Research Centre. </p>
<p>The water <a href="https://thirdworldcentre.org/communication-media/india-needs-to-radically-overhaul-its-water-institutions/">use in Delhi is 220 litres per capita per day</a> (lpcd), while some European cities boast figures of 95 to 120 lpcd.</p>
<p>Excess consumption is attributable in part to citizen indifference about conserving water after so many years of plentiful supply. Since large swaths of many Indian megacities lack piped supply of clean water, leaks and theft are common. Cities in India lose <a href="http://delhi.gov.in/wps/wcm/connect/d624c0004054d4aabea4fea1527a7156/ch-13.pdf?MOD=AJPERES&lmod=-888712437&CACHEID=d624c0004054d4aabea4fea1527a7156">40% to 50% due to leakages</a> and non-authorised connections. </p>
<p>At this point, the only viable option for India would seem to be managing demand and using water more efficiently.</p>
<p>The country is making tentative steps in that direction. <a href="http://www.wrmin.nic.in/writereaddata/Water_Framework_May_2016.pdf">The 2016 new National Water Framework</a>, passed emphasises the need for conservation and more efficient water use. </p>
<p>But under India’s Constitution, states are responsible for managing water, so central policies have little resonance. Neither the <a href="publications.iwmi.org/pdf/H042921.pdf">1987 and 2012 National Water Policy documents</a>, which contained similar recommendations to the 2016 policy, had any real impact on water use. </p>
<p>And after millennia of exclusive focus on expanding the water supply, the idea of curbing water consumption and increase reuse remains a mostly alien concept in India. </p>
<h2>Water wars</h2>
<p>Consistent supply-centric thinking has also resulted in competition for water as states negotiate the allocation of river water based on local needs. </p>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/173874/original/file-20170614-26091-1l2h0fc.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/173874/original/file-20170614-26091-1l2h0fc.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=679&fit=crop&dpr=1 600w, https://images.theconversation.com/files/173874/original/file-20170614-26091-1l2h0fc.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=679&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/173874/original/file-20170614-26091-1l2h0fc.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=679&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/173874/original/file-20170614-26091-1l2h0fc.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=853&fit=crop&dpr=1 754w, https://images.theconversation.com/files/173874/original/file-20170614-26091-1l2h0fc.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=853&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/173874/original/file-20170614-26091-1l2h0fc.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=853&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">India’s inter-state disputes on water usage have reached a critical point.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:India_rivers_and_lakes_map.svg">Wikimedia</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>The century-long conflict over <a href="http://wrmin.nic.in/writereaddata/Inter-StateWaterDisputes/Volume-I1920752696.pdf">the Cauvery River</a>, for example, involves Andhra Pradesh, Tamil Nadu, Karnataka – three major south Indian states. With each state demanding ever more water, the river simply cannot keep up. </p>
<p>In Karnataka, where agricultural policies are heavily skewed towards water-guzzling commercial crops, such as sugarcane, mismanaged ground and surface water are dying a slow death. Still the state continues to petition the Cauvery Water Dispute Tribunal for an increase in its share.</p>
<p>Water scarcity in Karnataka is aggravated by non-existent water quality management. Its rivers are choked with toxic pollutants, and oil-suffused <a href="https://www.theguardian.com/cities/2017/mar/01/burning-lakes-experts-fear-bangalore-uninhabitable-2025">lakes in Bengaluru, the capital, are reportedly catching fire</a>.</p>
<p>Meanwhile, in the northern part of the country, the <a href="http://conflicts.indiawaterportal.org/sites/conflicts.indiawaterportal.org/files/conflicts_sutlej_yamuna.pdf">Ravi-Beas River is causing conflict between Punjab and Haryana</a> states.</p>
<p>In India’s water wars, rivers are a resource to be harnessed and extracted for each riparian party’s maximum benefit. Very little emphasis has been placed on conserving and protecting existing water sources. And not one inter-state negotiation has prioritised pollution abatement or demand management. </p>
<p>Even policies from the national government, which claims to target water conservation and demand management, remain reliant on supply-side solutions. Big infrastructure programs, such as the <a href="http://www.nwda.gov.in/index2.asp?slid=108&sublinkid=14&langid=1">Indian river-linking plan</a>, envision large-scale water transfer from one river basin to another, again seeking to augment supply rather than conserve water and reduce consumption.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/173878/original/file-20170614-15456-1nv2bsf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/173878/original/file-20170614-15456-1nv2bsf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/173878/original/file-20170614-15456-1nv2bsf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/173878/original/file-20170614-15456-1nv2bsf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/173878/original/file-20170614-15456-1nv2bsf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/173878/original/file-20170614-15456-1nv2bsf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/173878/original/file-20170614-15456-1nv2bsf.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">Sand mining on the Cauvery river in 2017.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/biligiri/32171616363/">Prashanth NS/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>For inspiration on managing demand, India could look to <a href="http://www.switchurbanwater.eu/outputs/pdfs/W6-1_GEN_DEM_D6.1.6_Case_study_-_Berlin.pdf">Berlin in Germany</a>, <a href="http://www.iwra.org/congress/resource/abs461_article.pdf">Singapore</a> and <a href="http://onlinelibrary.wiley.com/store/10.1002/2014WR016301/asset/wrcr21265.pdf?v=1&t=j3k9yxa8&s=ad80a977e0adfcdec9e214b6cc500a2a1227704c">California</a>, all of which have designed and implemented such policies in recent years. Successful measures include raising public awareness, recycling water, fixing leaks, preventing theft and implementing conservation measures such as water harvesting and stormwater management. </p>
<p>Between rapidly disappearing fresh water, unchecked pollution and so many thirsty citizens, India is facing an impending water crisis unlike anything prior generations have seen. If the nation does not begin aggressively conserving water, the faucets will run soon dry. There is simply no more supply to misuse.</p><img src="https://counter.theconversation.com/content/78372/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>Hit by weak monsoons, India faces unprecedented water shortages.Asit K. Biswas, Distinguished Visiting Professor, Lee Kuan Yew School of Public Policy, National University of SingaporeCecilia Tortajada, Senior Research Fellow, Lee Kuan Yew School of Public Policy, National University of SingaporeUdisha Saklani, Independent Policy Researcher, National University of SingaporeLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/668592017-02-24T14:34:05Z2017-02-24T14:34:05ZStorm Doris: giving dangerous weather a human name makes us more wary, says research<p>Doris sounds like the sort of name your grandmother might have. It’s not particularly scary. But the name now has a rather different association, after “Storm Doris” tore through the UK. The Met Office, the UK’s national weather forecaster, put much of the country on “amber alert” and <a href="http://www.metoffice.gov.uk/barometer/uk-storm-centre/storm-doris">reported 94mph gusts</a> along with severe rain and snow.</p>
<p>The Met Office first warned about Doris <a href="https://twitter.com/metoffice/status/833987947020111872">several days earlier</a>, while it was still travelling across the North Atlantic. The idea is that giving storms human names makes them easy to remember and talk about, meaning people are more aware and prepared when they hit – certainly more prepared than if faced by a generic “high wind forecast”.</p>
<p>This is the second winter season in which the Met Office has run a pilot scheme to name these events. Each summer, it announces a list of names, alternating between male and female in alphabetical order, and the moment a new storm is spotted it acquires the next name on the list. Doris is the 15th storm to be named – and the fourth this season. The Met Office’s thinking is that names will better communicate dangerous, high-impact weather events to the public, and can thus streamline the warning system.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/158120/original/image-20170223-32722-4wjuwa.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/158120/original/image-20170223-32722-4wjuwa.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/158120/original/image-20170223-32722-4wjuwa.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=312&fit=crop&dpr=1 600w, https://images.theconversation.com/files/158120/original/image-20170223-32722-4wjuwa.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=312&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/158120/original/image-20170223-32722-4wjuwa.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=312&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/158120/original/image-20170223-32722-4wjuwa.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=393&fit=crop&dpr=1 754w, https://images.theconversation.com/files/158120/original/image-20170223-32722-4wjuwa.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=393&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/158120/original/image-20170223-32722-4wjuwa.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=393&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Doris warning in the Daily Mirror.</span>
<span class="attribution"><a class="source" href="https://twitter.com/DailyMirror/status/834166070873300994">Daily Mirror</a></span>
</figcaption>
</figure>
<p>Storm naming was first introduced in 1945 for <a href="http://www.aoml.noaa.gov/hrd/tcfaq/B2.html">Pacific typhoons</a> and was quickly picked up by the World Meteorology Organisation and in Europe and America. It is now very common across the world. Just think of “celebrities” such as Katrina, Sandy or Yolanda – the Philippine name for the incredibly destructive Typhoon Haiyan (itself a Chinese name).</p>
<p>The larger British storms often pick up unofficial names anyway. For instance, the 2013 <a href="http://www.metoffice.gov.uk/about-us/who/how/case-studies/st-judes-day-storm-oct-2013">“St Judes Day” storm </a> that travelled across southern England or the 2012 <a href="http://www.ncl.ac.uk/press/news/legacy/2012/07/thetoonmonsoonandflood.html">“Toon Monsoon” in Newcastle</a>. But because these events are named after they have happened, different media outlets can confuse the issue by calling them different things – the Newcastle storm, for instance, was also dubbed “<a href="http://www.chroniclelive.co.uk/news/north-east-news/newcastle-thunder-thursday-four-years-11535772">Thunder Thursday</a>”. </p>
<p>By having a predetermined list that runs <a href="http://www.metoffice.gov.uk/news/releases/2016/nameourstorms2016">from Angus to Wilbert</a>, the Met Office can name the storm before it hits, allowing a clear and more powerful warning. </p>
<h2>What counts as a storm?</h2>
<p>While the public and media consider any severe weather event to be a storm, the term has a much more specific meaning in meteorology (winds 10 or above on the Beaufort scale – that’s 55mph, or 89kmh). This meant heavy rainstorms with little wind could slip through unnamed and unhyped, despite the risk of floods. Indeed, heavy flooding just after Christmas 2015 was incorrectly attributed to Storm Frank when it actually came from nameless rainfall – exactly the sort of confusion the names were meant to avoid in the first place.</p>
<p>The Met Office has therefore had to relax its definition of what constitutes a “storm”. This season, all high-impact weather events are named. </p>
<h2>But does naming storms actually help?</h2>
<p>The most obvious benefit is that a name generates an instant hashtag and search term:</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"834687846422310912"}"></div></p>
<p>However, there are deeper effects, of which many people won’t even be conscious. Psychologists have shown that naming nonhuman agents and giving them human characteristics has a <a href="http://www.tandfonline.com/doi/full/10.1080/0163853X.2016.1223517?scroll=top&needAccess=true">positive effect on recall</a> and can <a href="https://faculty.fuqua.duke.edu/%7Egavan/bio/GJF_articles/anthropomorphized_objects_soc_cog_08.pdf">affect behaviour</a> as we seem to react with the same automatic behaviour to nonhumans assigned personality traits as we would to humans with the same personality traits. </p>
<p>It seems people really are more likely to be aware of Doris or Angus than a nameless storm warning – and indeed the Met’s own research backs this up: a recent <a href="http://www.metoffice.gov.uk/barometer/features/the-power-of-a-name">YouGov survey</a> has shown that storm naming has influenced behaviour with most people “taking action in some way upon hearing about a named storm”.</p>
<p>The choice of name can also influence perception. For instance, more masculine names and harder to pronounce names are perceived as <a href="http://pss.sagepub.com/content/20/2/135.abstract?ijkey=01540462a3a10356e2d27ee3a83798ed9a7883c8&keytype2=tf_ipsecsha%5D(http://pss.sagepub.com/content/20/2/135.abstract?ijkey=01540462a3a10356e2d27ee3a83798ed9a7883c8&keytype2=tf_ipsecsha">riskier</a>. Naming is such a powerful technique that some scientists even want to adopt it for <a href="http://www.tandfonline.com/doi/full/10.1080/10810730.2011.626503?scroll=top&needAccess=true">diseases and epidemics</a>.</p>
<p>Naming storms is fundamentally about communicating risk. Successful warning systems are based on reliable and effective partnerships between <a href="http://journals.ametsoc.org/doi/full/10.1175/BAMS-D-11-00150.1">forecasters, the media and emergency planners</a>. Storm naming has an important role to play in the communication of an event, but that is not the same as communicating what action should be taken. While the storm naming scheme has fostered cooperation between the Irish Met Éireann and the UK Met Office, continued and improved collaboration between all agencies involved in natural hazard management is needed to reduce impact further.</p><img src="https://counter.theconversation.com/content/66859/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Elizabeth Lewis receives funding from the Natural Environment Research Council and the European Research Council. </span></em></p>We’re more likely to remember a storm with a human face – and will prepare for it.Elizabeth Lewis, Research Associate, Water Group, Newcastle UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/694112016-12-19T19:07:23Z2016-12-19T19:07:23ZExplainer: what is the Australian monsoon?<figure><img src="https://images.theconversation.com/files/150231/original/image-20161215-2500-zngc4g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">In Darwin the wet season usually arrives around Christmas Day. </span> <span class="attribution"><span class="source">Storm image from www.shutterstock.com</span></span></figcaption></figure><p>Christmas in Darwin often means one thing: rain. The north is famous for its wet season, which runs from November to April, when the vast majority of the region’s rain falls.</p>
<p>The flora, fauna and people of the north have adapted to the Australian monsoon and now depend on the arrival of the rain for their survival. Living as we do on an arid continent, it is natural to eye this seasonal source of water as an important resource for <a href="http://industry.gov.au/ONA/WhitePaper/index.html">agriculture and other economic activity</a>. </p>
<p>But the summer monsoon is also notoriously fickle. Last year’s wet season was <a href="http://www.bom.gov.au/climate/updates/articles/a017.shtml">the driest since 1992</a>, although there is <a href="http://www.bom.gov.au/climate/outlooks/#/rainfall/median/seasonal/0">some evidence</a> that this year will be better. So what drives this important weather phenomenon, and how might it change in the future?</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/150233/original/image-20161215-2500-1q2ktxe.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/150233/original/image-20161215-2500-1q2ktxe.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/150233/original/image-20161215-2500-1q2ktxe.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=282&fit=crop&dpr=1 600w, https://images.theconversation.com/files/150233/original/image-20161215-2500-1q2ktxe.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=282&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/150233/original/image-20161215-2500-1q2ktxe.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=282&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/150233/original/image-20161215-2500-1q2ktxe.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=354&fit=crop&dpr=1 754w, https://images.theconversation.com/files/150233/original/image-20161215-2500-1q2ktxe.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=354&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/150233/original/image-20161215-2500-1q2ktxe.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=354&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Northern Australia’s wildlife is adapted to the wild swings between wet and dry.</span>
<span class="attribution"><span class="source">Crocodile image from www.shutterstock.com</span></span>
</figcaption>
</figure>
<h2>What is the Australian monsoon?</h2>
<p>The Australian monsoon actually alternates between two seasonal phases linked to wind direction. In the winter phase, easterly trade winds bring dry conditions. In the summer, westerly winds bring sustained rainy conditions. In fact, the word “monsoon” comes from the Arabic word for season.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/149348/original/image-20161208-31402-1pasc72.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/149348/original/image-20161208-31402-1pasc72.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=300&fit=crop&dpr=1 600w, https://images.theconversation.com/files/149348/original/image-20161208-31402-1pasc72.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=300&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/149348/original/image-20161208-31402-1pasc72.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=300&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/149348/original/image-20161208-31402-1pasc72.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=377&fit=crop&dpr=1 754w, https://images.theconversation.com/files/149348/original/image-20161208-31402-1pasc72.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=377&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/149348/original/image-20161208-31402-1pasc72.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=377&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Global rainfall daily averages (1979-2008) for the months of January (left) and July (right). The monsoon trough is positioned over northern Australia in the southern summer, and moves northward during the southern winter.</span>
<span class="attribution"><span class="source">NOAA/OAR/ESRL PSD (http://www.esrl.noaa.gov/psd/)</span></span>
</figcaption>
</figure>
<p>As the summer approaches, the sun heats the Australian land area faster than the surrounding ocean in much the same way as the pavement next to an outdoor swimming pool is heated faster than the pool water. </p>
<p>This difference in heating also produces a difference in pressure, which is lower over the land than the ocean. As a result, warm, moist air from the tropical ocean is drawn towards the lower pressure over the hot and dry north of Australia. It is this increase in humidity in the month or so prior to the sustained rains (known also as the “build-up”) that makes life so uncomfortable for many, driving some people “troppo”.</p>
<p>With increasing humidity, conditions become progressively better for the development of deep clouds and storms. </p>
<p>Eventually, sustained rain, low pressure (the “monsoon trough”) and deep westerly winds become established over land. This transition can be relatively abrupt, and at Darwin usually occurs around Christmas Day, although there is a great deal of variability from year to year.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/149345/original/image-20161208-31364-oj18s7.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/149345/original/image-20161208-31364-oj18s7.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=330&fit=crop&dpr=1 600w, https://images.theconversation.com/files/149345/original/image-20161208-31364-oj18s7.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=330&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/149345/original/image-20161208-31364-oj18s7.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=330&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/149345/original/image-20161208-31364-oj18s7.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=415&fit=crop&dpr=1 754w, https://images.theconversation.com/files/149345/original/image-20161208-31364-oj18s7.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=415&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/149345/original/image-20161208-31364-oj18s7.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=415&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Satellite image from December 27 2015, showing a tropical low in the Australian monsoon. This weather system contributed to the first big rainfall burst of the 2015/2016 summer monsoon.</span>
<span class="attribution"><span class="source">NASA Worldview (https://worldview.earthdata.nasa.gov/)</span></span>
</figcaption>
</figure>
<h2>Why so variable?</h2>
<p>Unsurprisingly, <a href="https://theconversation.com/explainer-el-nino-and-la-nina-27719">El Niño (and its counterpart, La Niña)</a> is partly responsible for the monsoon’s variability. </p>
<p>In El Niño years, the summer monsoon tends to be drier than average, and last year was no <a href="http://www.bom.gov.au/jsp/awap/rain/index.jsp?colour=colour&time=latest&step=1&map=decile&period=cnws&area=nat">exception</a>. </p>
<p>However, El Niño (or La Niña) usually influences only the early part of the season. Once the summer monsoon becomes established, the relationship with El Niño (or La Niña) becomes weaker.</p>
<p>The tropical oceans just to the north of Australia also play a role in the variability. Warmer-than-average sea surface temperatures and greater evaporation have contributed to an early onset of summer monsoon <a href="http://www.bom.gov.au/climate/rainfall-onset/">this year</a> by increasing the moisture early in the season. </p>
<p>Rainfall in the Australian summer monsoon occurs in a series of bursts, each of which may last for a few days or weeks. The relatively dry periods between the bursts are referred to as breaks, which can last for lengths similar to bursts. The total amount of rain that falls in a season depends on the intensity of the bursts, their number and their duration. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/149344/original/image-20161208-31405-bq19xk.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/149344/original/image-20161208-31405-bq19xk.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=345&fit=crop&dpr=1 600w, https://images.theconversation.com/files/149344/original/image-20161208-31405-bq19xk.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=345&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/149344/original/image-20161208-31405-bq19xk.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=345&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/149344/original/image-20161208-31405-bq19xk.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=434&fit=crop&dpr=1 754w, https://images.theconversation.com/files/149344/original/image-20161208-31405-bq19xk.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=434&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/149344/original/image-20161208-31405-bq19xk.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=434&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Daily rainfall averaged over land areas in the north of Australia for the period 1979-2010 (red), and the 2015/16 daily rainfall (blue). Although on average the rainfall over northern Australia is largest between January and February, in any given season the rainfall will occur in sporadic bursts as seen for the 2015/2016 summer monsoon.</span>
<span class="attribution"><span class="source">Bureau of Meteorology (http://www.bom.gov.au/jsp/awap/rain/index.jsp)</span></span>
</figcaption>
</figure>
<h2>The science of bursts</h2>
<p>One ingredient in rainfall bursts is the envelope of deep clouds known as the <a href="http://www.bom.gov.au/climate/mjo/">Madden-Julian Oscillation (MJO)</a>. This eastward-moving atmospheric wave organises deep clouds in the tropics and is often linked to widespread rainfall as it passes over the north of Australia. </p>
<p>This wave has a period (the length of time between rises and falls) of 30 to 60 days, and is closely <a href="http://poama.bom.gov.au/climate/mjo/#tabs=MJO-phase">monitored</a> by the Australian Bureau of Meteorology. </p>
<p><a href="http://journals.ametsoc.org/doi/abs/10.1175/JAS-D-15-0071.1">Recent research</a> has shown that a second important ingredient is the mid-latitude troughs (zones of low pressure) that periodically move towards the equator into the tropics. Such troughs rapidly increase the moisture in the monsoon trough and are associated with two-thirds of all bursts.</p>
<p><a href="http://www.bom.gov.au/climate/about/">These influences</a> also work together to produce rainfall bursts in the Australian monsoon.</p>
<h2>What about climate change?</h2>
<p>The <a href="https://www.climatechangeinaustralia.gov.au/en/climate-projections/future-climate/regional-climate-change-explorer/super-clusters/">jury is still out</a> on this one, although there are hints as to what might be ahead. </p>
<p>State-of-the-art climate models furiously disagree on whether there will be more or less rainfall and how much more or less in the north of Australia. Although there are reasons to believe that the monsoon regions may become wetter in a warmer world, monsoons pose a challenge for climate models as they depend very strongly on the relationship between the atmosphere, the land and the ocean. </p>
<p>However, recent advances in understanding the role of the mid-latitudes in producing rainfall bursts may help us to untangle some of the uncertainties in the models. </p>
<p>The continuing research into understanding and predicting the Australian summer monsoon will help in planning for the future in this important region.</p><img src="https://counter.theconversation.com/content/69411/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Sugata Narsey receives funding from the Australian Research Council Centre of Excellence for Climate Systems Science. </span></em></p><p class="fine-print"><em><span>Michael Reeder receives funding from Australian Research Council Centre of Excellence for Climate System Science. </span></em></p>The Australian monsoon delivers most of northern Australia’s rainfall and is a vital feature of life in the region. But why does it occur?Sugata Narsey, PhD Candidate, Monash UniversityMichael Reeder, Professor, School of Earth, Atmosphere and Environment, Monash UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/598232016-05-25T20:12:00Z2016-05-25T20:12:00ZEl Niño is over, but has left its mark across the world<figure><img src="https://images.theconversation.com/files/123739/original/image-20160524-11032-1r1qls6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Eventually reduced rainfall hit much of Australia thanks to El Niño.</span> <span class="attribution"><span class="source">Andrew Watkins</span>, <span class="license">Author provided</span></span></figcaption></figure><p>The 2015-16 El Niño has <a href="http://www.bom.gov.au/climate/enso/">likely reached its end</a>. Tropical Pacific Ocean temperatures, trade winds, cloud and pressure patterns have all dropped back to near normal, although clearly the event’s impacts around the globe are still being felt.</p>
<p>Recent changes in Pacific Ocean temperatures have been comparable to the decline seen at the end of the 1998 El Niño, although temperatures remain warmer than at the end of the most recent El Niño in 2010. Models suggest that ocean cooling will continue, with little chance of a return to El Niño levels in the immediate future.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/123729/original/image-20160524-12397-1r8s1li.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/123729/original/image-20160524-12397-1r8s1li.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/123729/original/image-20160524-12397-1r8s1li.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=493&fit=crop&dpr=1 600w, https://images.theconversation.com/files/123729/original/image-20160524-12397-1r8s1li.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=493&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/123729/original/image-20160524-12397-1r8s1li.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=493&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/123729/original/image-20160524-12397-1r8s1li.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=620&fit=crop&dpr=1 754w, https://images.theconversation.com/files/123729/original/image-20160524-12397-1r8s1li.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=620&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/123729/original/image-20160524-12397-1r8s1li.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=620&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 observed and forecast decline of the 2015-16 El Niño, compared to the record event of 1997-98 and the previous El Niño in 2009-10.</span>
<span class="attribution"><span class="source">Australian Bureau of Meteorology</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>The 2015–16 El Niño will go down as one of the three strongest El Niño events since 1950. Every El Niño is different, but typically the stronger the event, the greater its global impact. The 2015–16 El Niño was no exception, with wide-ranging effects felt around the world. </p>
<p>El Niño also added to the globe’s warming trend, making <a href="https://theconversation.com/2016-is-likely-to-be-the-worlds-hottest-year-heres-why-59378">2015 the world’s hottest calendar year on record</a>. Early indications are that 2016 could be hotter still.</p>
<p>So as El Niño fades, let’s take stock of its impacts worldwide. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/123525/original/image-20160523-9534-jj6ide.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/123525/original/image-20160523-9534-jj6ide.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/123525/original/image-20160523-9534-jj6ide.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/123525/original/image-20160523-9534-jj6ide.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/123525/original/image-20160523-9534-jj6ide.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/123525/original/image-20160523-9534-jj6ide.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/123525/original/image-20160523-9534-jj6ide.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/123525/original/image-20160523-9534-jj6ide.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">Typical impacts of El Niño across the globe.</span>
<span class="attribution"><span class="source">Australian Bureau of Meteorology</span></span>
</figcaption>
</figure>
<h2>Australia</h2>
<p>El Niño is often, but not always, associated with <a href="https://theconversation.com/when-the-indian-ocean-and-el-nino-join-forces-things-can-get-hot-and-dry-48969">drought in Australia</a>. But the drying influence of the 2015-16 El Niño was initially tempered somewhat by very warm temperatures in the Indian Ocean. From April to August, above-average rainfall fell over parts of inland Western Australia, New South Wales and eastern Victoria. </p>
<p>But by spring, the Indian Ocean was helping El Niño, resulting in Australia’s third-driest spring on record, limiting growth at the end of the cropping season. A record early heatwave in October further <a href="http://www.farmonline.com.au/news/agriculture/cropping/grains/el-nio-hammers-wheat-crop/2745601.aspx">reduced crop production in the Murray–Darling Basin</a>.</p>
<p>However, the lack of heavy rains in the north and west meant <a href="http://www.reuters.com/article/us-mining-australia-elnino-idUSKCN0S601W20151012">reduced downtime for mining</a>.</p>
<p>The northern wet season produced a record-low three tropical cyclones in the Australian region. The previous record was five, which happened in 1987-88 and again in 2006-07 – both El Niño years. </p>
<p>Fewer clouds and less tropical rain contributed to the <a href="https://theconversation.com/au/topics/coral-bleaching">most severe coral bleaching</a> event on record for the Great Barrier Reef.</p>
<p>The combination of heat and low rainfall brought a very early start to the fire season, with more than 70 fires burning in Victoria and around 55 fires in Tasmania during October. Dry conditions in Tasmania also resulted in hundreds of fires being started by dry lightning in mid-January 2016. The <a href="https://theconversation.com/fires-in-tasmanias-ancient-forests-are-a-warning-for-all-of-us-53806">fires damaged large areas of the Tasmanian Wilderness World Heritage Area</a>, including areas of rainforest and bogs, which may not have seen fire for centuries. </p>
<h2>The Pacific region</h2>
<p>In Papua New Guinea, <a href="https://theconversation.com/as-papua-new-guinea-faces-worsening-drought-a-past-disaster-could-save-lives-46390">drought and frost led to crop failures and food shortages</a>. Staple sweet potato crops in the highlands were severely damaged by August frosts – the result of El Niño reducing night-time cloud cover – which also destroyed wild plants that are usually eaten as a backup source of food. </p>
<p>Vanuatu, Fiji, the Solomon Islands, Samoa and Tonga experienced <a href="http://www.sbs.com.au/news/article/2015/12/14/el-nino-warning-bells-ringing-oxfam">worsening drought</a>. Islands closer to the Equator such as Kiribati and Tuvalu had intense rain causing flooding, as well as higher sea levels due to warmer waters and weaker trade winds.</p>
<h2>Asia</h2>
<p>In the Philippines, drought was declared in 85% of provinces. Indonesia experienced its worst drought in 18 years. <a href="https://theconversation.com/indonesia-fires-threaten-to-send-even-modest-climate-ambitions-up-in-smoke-49155">Forest fires caused poor air quality</a> over vast neighbouring areas including Singapore, Malaysia, southern Thailand and the southern Philippines. </p>
<p>In the Mekong Basin, delayed monsoon rains reduced rice production, with significant reductions in Vietnam. In Thailand, severe water shortages led to water rationing and delayed rice planting. The Thai government <a href="http://time.com/3960462/thailand-drought/">lowered its forecast for rice exports</a> by two million tonnes. This led to some African countries increasing their imports, fearing a price rise. </p>
<p><a href="http://www.bloomberg.com/news/articles/2016-03-28/malaysian-palm-oil-production-to-worsen-on-el-nino-mistry-says">Palm oil prices rose</a> as supplies became limited due to drought in Malaysia and Indonesia. In April 2016, a heatwave set national temperature records for Thailand, Laos and Cambodia. </p>
<p>Northern parts of China experienced drought in 2015. Heavy rainfall in southern China persisted through the second half of 2015, with flooding and landslides recorded along the Yangtze River Valley. China’s December-to-February rainfall was approximately 50% above normal. In May 2016, heavy rain caused <a href="http://www.scmp.com/news/china/society/article/1949392/torrential-rains-claim-eight-lives-southern-chinas-guangdong">flooding and landslides in China’s Guangdong province</a>.</p>
<p>In India, <a href="http://www.bloomberg.com/news/articles/2016-05-03/india-is-suffering-one-of-its-worst-droughts-in-decades">below-average monsoon rains</a> in June to September led to reduced rice, corn, cotton and sugar output in 2015. Below-average rainfall between October and December also affected India’s wheat harvest. Major water shortages emerged in some areas, including Mumbai – the result of two years of failed rains. </p>
<p>Indian Premier League cricket matches were relocated from Mumbai, Pune and Nagpur due to water restrictions. Record heat affected the north and west of the country in May, setting a <a href="http://reliefweb.int/report/india/india-sets-new-heat-record-temperatures-soar">new national record of 51°C</a> in Phalodi.</p>
<p>Conversely, some <a href="https://www.washingtonpost.com/news/capital-weather-gang/wp/2015/12/10/before-and-after-satellite-imagery-of-the-historic-flooding-in-chennai-india/">southern parts of India had exceptionally wet conditions</a>, with record-breaking rains and widespread flooding in Chennai in November and December. The city received over 300mm of rainfall on December 1, 2015; the wettest day in more than a century.</p>
<h2>South and Central America</h2>
<p>Peru experienced widespread flooding and mudslides in early 2016, with heavy rain leaving more than 5,000 people homeless. In Ecuador, flooding and landslides damaged properties and affected shrimp production. </p>
<p>More than 150,000 people were evacuated from <a href="http://www.bbc.com/news/world-latin-america-35184793">flooded areas in Paraguay, Uruguay, Brazil, and Argentina</a> in December 2015. Some experts have linked El Niño flooding to outbreaks of <a href="http://who.int/hac/crises/el-nino/22february2016/en/">mosquito-borne diseases such as Zika virus</a>.</p>
<p>In January 2016, Argentina experienced its worst locust plague since 1954, following heavy rains and warm temperatures. Heavy rains returned to Argentina and Paraguay in April 2016, causing large agricultural losses.</p>
<p>In contrast, <a href="http://latincorrespondent.com/2016/02/el-nino-wreaks-havoc-in-colombia/">Colombia experienced drought and forest fires</a>, which caused severe damage to crops and pushed up food prices, leading to malnutrition in some areas. In November 2015, the United Nations warned that 2.3 million people would need food aid in Central America.</p>
<p>The Caribbean also experienced drought; Cuba had its most severe dry season in 115 years; Barbados, Dominica, the Virgin Islands, Puerto Rico, Antigua, Barbuda and Saint Lucia experienced water shortages, with the latter declaring a national emergency. The Dominican Republic experienced serious agricultural losses.</p>
<p>Brazil had a particularly high number of forest fires during 2015, exacerbated by ongoing drought conditions in the Amazon region. Drought in Brazil and Colombia (and Indonesia) meant <a href="https://weather.com/science/environment/news/el-nino-weather-damages-coffee-crops">coffee prices soared</a> as dry conditions affected all the major coffee-producing countries. </p>
<p>In contrast, excess rain in northeast Brazil flooded crops, leading to rises in the sugar price worldwide.</p>
<h2>North America</h2>
<p>In California, many hoped that El Niño would bring relief from five years of drought. But despite some regions getting heavy rain more typical of El Niño, leading to mudslides, El Niño failed to end the long-term dry. </p>
<p>In the southeast and south-central United States, rainfall was above normal. Major flooding occurred along the Mississippi River. Missouri received three times its normal rainfall during November and December 2015. </p>
<p><a href="http://www.abc.net.au/news/2016-05-17/crabs-carpet-california-beaches/7420956">Warmer-than-average sea surface temperatures</a> offshore meant warm water species such as sea snakes, red tuna crabs and hammerhead sharks were found on Californian beaches. </p>
<h2>Africa</h2>
<p>Drought meant that <a href="https://www.iol.co.za/business/news/farmers-owe-banks-r125bn-as-crops-wither-1971244">South African food production</a> was around six million tonnes below normal levels — the lowest since 1995. </p>
<p>In Zimbabwe, Malawi and Mozambique, maize prices were at least 50% higher than usual, with drought unlikely to break until rains in summer 2016–17. In the <a href="https://www.climate.gov/news-features/event-tracker/not-so-rainy-season-drought-southern-africa-january-2016">driest areas of Zimbabwe</a>, more than 75% of crops were lost. In May 2016, Zimbabwean national parks put wildlife up for sale in a bid to save animals from drought.</p>
<p>The <a href="http://www.theaustralian.com.au/news/world/the-times/chocolate-prices-to-rise-as-el-nino-brings-big-dry-to-west-africa/news-story/7b68da82787af93e2557435638699c47">cost of chocolate</a> hit a four-year high as a result of drought and lost production in the world’s major cocoa producer, Ivory Coast. </p>
<p>Drought also affected Ethiopia, Somalia, Swaziland, Zambia and parts of Madagascar, with more than 10 million Ethiopians in need of food aid. </p>
<p>In December 2015, <a href="http://www.fao.org/3/a-i5282e.pdf">Rift Valley fever</a> was reported in East Africa. The disease is associated with heavy rainfall providing a fertile breeding ground for the mosquitoes that carry the virus. </p>
<p>In Tanzania, <a href="http://www.dw.com/en/el-nino-induced-floods-ravage-east-africa/a-19245333">heavy rain destroyed crops and food reserves</a>, while in Kenya <a href="http://www.unocha.org/el-nino-southern-africa">heavy rains aggravated cholera outbreaks</a>. In May 2016, landslides in Rwanda cost many lives and heavy rains damaged infrastructure and hundreds of homes.</p>
<p><em>For information on the current and forecast state of ENSO, keep an eye on <a href="http://www.bom.gov.au/climate/enso/">the Bureau’s ENSO Wrap-Up</a>.</em></p><img src="https://counter.theconversation.com/content/59823/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>From floods to drought, fire to famine, the 2015-16 El Nino has had a global impact.Alison Cook, Climatologist, Australian Bureau of MeteorologyAndrew B. Watkins, Manager of Climate Prediction Services, Australian Bureau of MeteorologyBlair Trewin, Climatologist, National Climate Centre, Australian Bureau of MeteorologyCatherine Ganter, Senior Climatologist, Australian Bureau of MeteorologyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/599932016-05-25T13:30:51Z2016-05-25T13:30:51ZEl Niño is over, but has left its mark across the world<figure><img src="https://images.theconversation.com/files/123923/original/image-20160525-25218-zds39v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">As a result of El Niño, Africa saw droughts in many regions.</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>The 2015-16 El Niño has <a href="http://www.bom.gov.au/climate/enso/">likely reached its end</a>. Tropical Pacific Ocean temperatures, trade winds, cloud and pressure patterns have all dropped back to near normal, although clearly the event’s impacts around the globe are still being felt.</p>
<p>Recent changes in Pacific Ocean temperatures have been comparable to the decline seen at the end of the 1998 El Niño, although temperatures remain warmer than at the end of the most recent El Niño in 2010. Models suggest that ocean cooling will continue, with little chance of a return to El Niño levels in the immediate future.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/123729/original/image-20160524-12397-1r8s1li.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/123729/original/image-20160524-12397-1r8s1li.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/123729/original/image-20160524-12397-1r8s1li.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=493&fit=crop&dpr=1 600w, https://images.theconversation.com/files/123729/original/image-20160524-12397-1r8s1li.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=493&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/123729/original/image-20160524-12397-1r8s1li.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=493&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/123729/original/image-20160524-12397-1r8s1li.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=620&fit=crop&dpr=1 754w, https://images.theconversation.com/files/123729/original/image-20160524-12397-1r8s1li.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=620&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/123729/original/image-20160524-12397-1r8s1li.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=620&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 observed and forecast decline of the 2015-16 El Niño, compared to the record event of 1997-98 and the previous El Niño in 2009-10.</span>
<span class="attribution"><span class="source">Australian Bureau of Meteorology</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>The 2015–16 El Niño will go down as one of the three strongest El Niño events since 1950. Every El Niño is different, but typically the stronger the event, the greater its global impact. The 2015–16 El Niño was no exception, with wide-ranging effects felt around the world. </p>
<p>El Niño also added to the globe’s warming trend, making <a href="https://theconversation.com/2016-is-likely-to-be-the-worlds-hottest-year-heres-why-59378">2015 the world’s hottest calendar year on record</a>. Early indications are that 2016 could be hotter still.</p>
<p>So as El Niño fades, let’s take stock of its impacts worldwide. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/123525/original/image-20160523-9534-jj6ide.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/123525/original/image-20160523-9534-jj6ide.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/123525/original/image-20160523-9534-jj6ide.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/123525/original/image-20160523-9534-jj6ide.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/123525/original/image-20160523-9534-jj6ide.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/123525/original/image-20160523-9534-jj6ide.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/123525/original/image-20160523-9534-jj6ide.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/123525/original/image-20160523-9534-jj6ide.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">Typical impacts of El Niño across the globe.</span>
<span class="attribution"><span class="source">Australian Bureau of Meteorology</span></span>
</figcaption>
</figure>
<h2>Africa</h2>
<p>Drought meant that <a href="https://www.iol.co.za/business/news/farmers-owe-banks-r125bn-as-crops-wither-1971244">South African food production</a> was around six million tonnes below normal levels — the lowest since 1995. </p>
<p>In Zimbabwe, Malawi and Mozambique, maize prices were at least 50% higher than usual, with drought unlikely to break until rains in summer 2016–17. In the <a href="https://www.climate.gov/news-features/event-tracker/not-so-rainy-season-drought-southern-africa-january-2016">driest areas of Zimbabwe</a>, more than 75% of crops were lost. In May 2016, Zimbabwean national parks put wildlife up for sale in a bid to save animals from drought.</p>
<p>The <a href="http://www.theaustralian.com.au/news/world/the-times/chocolate-prices-to-rise-as-el-nino-brings-big-dry-to-west-africa/news-story/7b68da82787af93e2557435638699c47">cost of chocolate</a> hit a four-year high as a result of drought and lost production in the world’s major cocoa producer, Ivory Coast. </p>
<p>Drought also affected Ethiopia, Somalia, Swaziland, Zambia and parts of Madagascar, with more than 10 million Ethiopians in need of food aid. </p>
<p>In December 2015, <a href="http://www.fao.org/3/a-i5282e.pdf">Rift Valley fever</a> was reported in East Africa. The disease is associated with heavy rainfall providing a fertile breeding ground for the mosquitoes that carry the virus. </p>
<p>In Tanzania, <a href="http://www.dw.com/en/el-nino-induced-floods-ravage-east-africa/a-19245333">heavy rain destroyed crops and food reserves</a>, while in Kenya <a href="http://www.unocha.org/el-nino-southern-africa">heavy rains aggravated cholera outbreaks</a>. In May 2016, landslides in Rwanda cost many lives and heavy rains damaged infrastructure and hundreds of homes.</p>
<h2>The Pacific region</h2>
<p>El Niño is often, but not always, associated with <a href="https://theconversation.com/when-the-indian-ocean-and-el-nino-join-forces-things-can-get-hot-and-dry-48969">drought in Australia</a>. But the drying influence of the 2015-16 El Niño was initially tempered somewhat by very warm temperatures in the Indian Ocean. From April to August, above-average rainfall fell over parts of inland Western Australia, New South Wales and eastern Victoria. </p>
<p>But by spring, the Indian Ocean was helping El Niño, resulting in Australia’s third-driest spring on record, limiting growth at the end of the cropping season. A record early heatwave in October further <a href="http://www.farmonline.com.au/news/agriculture/cropping/grains/el-nio-hammers-wheat-crop/2745601.aspx">reduced crop production in the Murray–Darling Basin</a>.</p>
<p>However, the lack of heavy rains in the north and west meant <a href="http://www.reuters.com/article/us-mining-australia-elnino-idUSKCN0S601W20151012">reduced downtime for mining</a>.</p>
<p>The northern wet season produced a record-low three tropical cyclones in the Australian region. The previous record was five, which happened in 1987-88 and again in 2006-07 – both El Niño years. </p>
<p>Fewer clouds and less tropical rain contributed to the <a href="https://theconversation.com/au/topics/coral-bleaching">most severe coral bleaching</a> event on record for the Great Barrier Reef.</p>
<p>The combination of heat and low rainfall brought a very early start to the fire season, with more than 70 fires burning in Victoria and around 55 fires in Tasmania during October. Dry conditions in Tasmania also resulted in hundreds of fires being started by dry lightning in mid-January 2016. The <a href="https://theconversation.com/fires-in-tasmanias-ancient-forests-are-a-warning-for-all-of-us-53806">fires damaged large areas of the Tasmanian Wilderness World Heritage Area</a>, including areas of rainforest and bogs, which may not have seen fire for centuries. </p>
<p>In Papua New Guinea, <a href="https://theconversation.com/as-papua-new-guinea-faces-worsening-drought-a-past-disaster-could-save-lives-46390">drought and frost led to crop failures and food shortages</a>. Staple sweet potato crops in the highlands were severely damaged by August frosts – the result of El Niño reducing night-time cloud cover – which also destroyed wild plants that are usually eaten as a backup source of food. </p>
<p>Vanuatu, Fiji, the Solomon Islands, Samoa and Tonga experienced <a href="http://www.sbs.com.au/news/article/2015/12/14/el-nino-warning-bells-ringing-oxfam">worsening drought</a>. Islands closer to the Equator such as Kiribati and Tuvalu had intense rain causing flooding, as well as higher sea levels due to warmer waters and weaker trade winds.</p>
<h2>Asia</h2>
<p>In the Philippines, drought was declared in 85% of provinces. Indonesia experienced its worst drought in 18 years. <a href="https://theconversation.com/indonesia-fires-threaten-to-send-even-modest-climate-ambitions-up-in-smoke-49155">Forest fires caused poor air quality</a> over vast neighbouring areas including Singapore, Malaysia, southern Thailand and the southern Philippines. </p>
<p>In the Mekong Basin, delayed monsoon rains reduced rice production, with significant reductions in Vietnam. In Thailand, severe water shortages led to water rationing and delayed rice planting. The Thai government <a href="http://time.com/3960462/thailand-drought/">lowered its forecast for rice exports</a> by two million tonnes. This led to some African countries increasing their imports, fearing a price rise. </p>
<p><a href="http://www.bloomberg.com/news/articles/2016-03-28/malaysian-palm-oil-production-to-worsen-on-el-nino-mistry-says">Palm oil prices rose</a> as supplies became limited due to drought in Malaysia and Indonesia. In April 2016, a heatwave set national temperature records for Thailand, Laos and Cambodia. </p>
<p>Northern parts of China experienced drought in 2015. Heavy rainfall in southern China persisted through the second half of 2015, with flooding and landslides recorded along the Yangtze River Valley. China’s December-to-February rainfall was approximately 50% above normal. In May 2016, heavy rain caused <a href="http://www.scmp.com/news/china/society/article/1949392/torrential-rains-claim-eight-lives-southern-chinas-guangdong">flooding and landslides in China’s Guangdong province</a>.</p>
<p>In India, <a href="http://www.bloomberg.com/news/articles/2016-05-03/india-is-suffering-one-of-its-worst-droughts-in-decades">below-average monsoon rains</a> in June to September led to reduced rice, corn, cotton and sugar output in 2015. Below-average rainfall between October and December also affected India’s wheat harvest. Major water shortages emerged in some areas, including Mumbai – the result of two years of failed rains. </p>
<p>Indian Premier League cricket matches were relocated from Mumbai, Pune and Nagpur due to water restrictions. Record heat affected the north and west of the country in May, setting a <a href="http://reliefweb.int/report/india/india-sets-new-heat-record-temperatures-soar">new national record of 51°C</a> in Phalodi.</p>
<p>Conversely, some <a href="https://www.washingtonpost.com/news/capital-weather-gang/wp/2015/12/10/before-and-after-satellite-imagery-of-the-historic-flooding-in-chennai-india/">southern parts of India had exceptionally wet conditions</a>, with record-breaking rains and widespread flooding in Chennai in November and December. The city received over 300mm of rainfall on December 1, 2015; the wettest day in more than a century.</p>
<h2>South and Central America</h2>
<p>Peru experienced widespread flooding and mudslides in early 2016, with heavy rain leaving more than 5,000 people homeless. In Ecuador, flooding and landslides damaged properties and affected shrimp production. </p>
<p>More than 150,000 people were evacuated from <a href="http://www.bbc.com/news/world-latin-america-35184793">flooded areas in Paraguay, Uruguay, Brazil, and Argentina</a> in December 2015. Some experts have linked El Niño flooding to outbreaks of <a href="http://who.int/hac/crises/el-nino/22february2016/en/">mosquito-borne diseases such as Zika virus</a>.</p>
<p>In January 2016, Argentina experienced its worst locust plague since 1954, following heavy rains and warm temperatures. Heavy rains returned to Argentina and Paraguay in April 2016, causing large agricultural losses.</p>
<p>In contrast, <a href="http://latincorrespondent.com/2016/02/el-nino-wreaks-havoc-in-colombia/">Colombia experienced drought and forest fires</a>, which caused severe damage to crops and pushed up food prices, leading to malnutrition in some areas. In November 2015, the United Nations warned that 2.3 million people would need food aid in Central America.</p>
<p>The Caribbean also experienced drought; Cuba had its most severe dry season in 115 years; Barbados, Dominica, the Virgin Islands, Puerto Rico, Antigua, Barbuda and Saint Lucia experienced water shortages, with the latter declaring a national emergency. The Dominican Republic experienced serious agricultural losses.</p>
<p>Brazil had a particularly high number of forest fires during 2015, exacerbated by ongoing drought conditions in the Amazon region. Drought in Brazil and Colombia (and Indonesia) meant <a href="https://weather.com/science/environment/news/el-nino-weather-damages-coffee-crops">coffee prices soared</a> as dry conditions affected all the major coffee-producing countries. </p>
<p>In contrast, excess rain in northeast Brazil flooded crops, leading to rises in the sugar price worldwide.</p>
<h2>North America</h2>
<p>In California, many hoped that El Niño would bring relief from five years of drought. But despite some regions getting heavy rain more typical of El Niño, leading to mudslides, El Niño failed to end the long-term dry. </p>
<p>In the southeast and south-central United States, rainfall was above normal. Major flooding occurred along the Mississippi River. Missouri received three times its normal rainfall during November and December 2015. </p>
<p><a href="http://www.abc.net.au/news/2016-05-17/crabs-carpet-california-beaches/7420956">Warmer-than-average sea surface temperatures</a> offshore meant warm water species such as sea snakes, red tuna crabs and hammerhead sharks were found on Californian beaches. </p>
<p><em>For information on the current and forecast state of ENSO, keep an eye on <a href="http://www.bom.gov.au/climate/enso/">the Bureau’s ENSO Wrap-Up</a>.</em></p><img src="https://counter.theconversation.com/content/59993/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>From floods to drought, fire to famine, the 2015-16 El Nino has had a global impact.Alison Cook, Climatologist, Australian Bureau of MeteorologyAndrew B. Watkins, Manager of Climate Prediction Services, Australian Bureau of MeteorologyBlair Trewin, Climatologist, National Climate Centre, Australian Bureau of MeteorologyCatherine Ganter, Senior Climatologist, Australian Bureau of MeteorologyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/435442015-07-30T20:17:32Z2015-07-30T20:17:32ZDigging deep into the past to see the future of climate change<figure><img src="https://images.theconversation.com/files/89774/original/image-20150727-7665-12ji57q.jpg?ixlib=rb-1.1.0&rect=1585%2C0%2C2826%2C1996&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Rain approaching the Pinnacles in Western Australia -- how best to understand what past climate change has had on the region?</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/rubberducky_me/6084907380/">Flickr/Matt Brand</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>When did Australia’s climate become so dry? When did tropical reefs around Australia develop? And what will happen to Australia’s climate and reefs in the future?</p>
<p>The answer to these questions can be found by digging into the distant past. That means digging deep into the Earth’s crust, and you don’t always need to be on dry land to do that.</p>
<p>The US scientific ship <a href="http://joidesresolution.org/">JOIDES Resolution</a> is capable of drilling deep under the ocean’s floor. It will depart Fremantle, in Western Australia, next month on a <a href="http://iodp.tamu.edu/scienceops/expeditions/indonesian_throughflow.html">two month expedition</a> to help shed light on some of the mysteries about Australia’s past. On board will be an international team of 30 scientists co-led by myself.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/89767/original/image-20150727-28929-rd3wwx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/89767/original/image-20150727-28929-rd3wwx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/89767/original/image-20150727-28929-rd3wwx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/89767/original/image-20150727-28929-rd3wwx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/89767/original/image-20150727-28929-rd3wwx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/89767/original/image-20150727-28929-rd3wwx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/89767/original/image-20150727-28929-rd3wwx.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">The JOIDES Resolution will be drilling holes in the seabed off the coast of Western Australia.</span>
<span class="attribution"><span class="source">International Ocean Discovery Program</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>The JOIDES Resolution is named in honour of <a href="http://www.captaincooksociety.com/home/detail/resolution">HMS Resolution</a> that was commanded by Captain James Cook more than 200 years ago when he explored the Pacific Ocean. It is the flagship of the International Ocean Discovery Program (<a href="http://www.iodp.org/">IODP</a>), the world’s largest Earth science program whose country members include Australia and New Zealand.</p>
<p>The plan is to travel from Fremantle to Darwin and drill a series of cores of up to a kilometre deep into the seabed. This will give us a five million year history of climate and environmental change off the west coast of Australia.</p>
<p>Ocean drilling is the best method to directly sample the layers beneath the sea bed and it tells us how the Earth has worked in the past, how it is working now and how it might work in the future.</p>
<h2>The origin of Australia’s western tropical reefs</h2>
<p>The history of Australia’s climate is linked to oceanic conditions off its coastline.</p>
<p>Tropical reefs such as the <a href="https://en.wikipedia.org/wiki/Houtman_Abrolhos">Houtman-Abrolhos reefs</a> off western Australia are controlled by the warm southward flowing offshore Leeuwin Current. This current is related to the global circulation system of ocean currents that travels through the Indonesian archipelago, called the Indonesian Throughflow.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/89766/original/image-20150727-28946-4i55u9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/89766/original/image-20150727-28946-4i55u9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/89766/original/image-20150727-28946-4i55u9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=358&fit=crop&dpr=1 600w, https://images.theconversation.com/files/89766/original/image-20150727-28946-4i55u9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=358&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/89766/original/image-20150727-28946-4i55u9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=358&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/89766/original/image-20150727-28946-4i55u9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=450&fit=crop&dpr=1 754w, https://images.theconversation.com/files/89766/original/image-20150727-28946-4i55u9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=450&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/89766/original/image-20150727-28946-4i55u9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=450&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Currents around Australia (red = warm, blue = cold) with the geographic extent of the summer monsoon (dashed green lines). Yellow stars show the position of the three groups of proposed drilling sites.</span>
<span class="attribution"><span class="source">Stephen John Gallagher</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Global ocean circulation controls the Earth’s climate. It transports water heat from the Pacific to the Indian Ocean and then to the poles.</p>
<p>Previous <a href="http://publications.iodp.org/scientific_prospectus/356/">research</a>
has shown that ocean circulation in the Indian Ocean slowed down or nearly stopped near the Indonesian archipelago many times in the past. Every time this happened, the global climate changed, leading to cooling of the Indian Ocean and drier climates.</p>
<p>Our expedition hopes to study fossils and sediments in the layers from below the seabed to chart the history of these ocean features over millions of years. We seek to understand how global ocean circulation has changed and its climatic consequences.</p>
<p>The aim is to establish when tropical conditions suitable for reef growth first occurred and whether these conditions have changed over millions of years.</p>
<p>Looking into the past history of these reefs and ocean currents will improve our understanding of how modern reefs and currents off west Australia might behave with future climate change.</p>
<h2>The history of the Australian monsoon</h2>
<p>At present the climate of the northern half of Australia is highly influenced by seasonal rain variability. Monsoonal rains provide periodic relief to central Australia’s arid centre as the tropical monsoonal belt migrates southward from Indonesia during the summer months.</p>
<p>Even though there are large floods associated with these events, most of the Australian continent is still arid.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/89773/original/image-20150727-7659-1052i8z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/89773/original/image-20150727-7659-1052i8z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/89773/original/image-20150727-7659-1052i8z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=429&fit=crop&dpr=1 600w, https://images.theconversation.com/files/89773/original/image-20150727-7659-1052i8z.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=429&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/89773/original/image-20150727-7659-1052i8z.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=429&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/89773/original/image-20150727-7659-1052i8z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=539&fit=crop&dpr=1 754w, https://images.theconversation.com/files/89773/original/image-20150727-7659-1052i8z.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=539&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/89773/original/image-20150727-7659-1052i8z.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=539&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Western Australia has been hit by many Tropical Cyclones over the years including TC Bianca in January 2011.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/gsfc/5390366115/">NASA/GSFC/Jeff Schmaltz/MODIS Land Rapid Response Team</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Previous <a href="http://www.australasianscience.com.au/article/issue-june-2010/how-australia-dried-out.html">work</a>
in the southern half of Australia suggests our present arid conditions are relatively recent in Australia’s geological history. These arid conditions were well established by around 1.5 million years ago.</p>
<p>But there are no similar histories of conditions in Australia’s northwest region. In addition, the long term history of the monsoon and aridity is not well known beyond a few hundred thousand years.</p>
<p>The reason for this is that no one has yet drilled deep enough beneath the sea bed to get million year scale records. In addition, long-term records of climate change in the arid zone of Australia do not preserve easily as conditions are so harsh.</p>
<p>Fortunately, sediment from monsoonal rivers flows into the sea in the region and is trapped in layers close to the continental margin, creating an excellent record of climate change.</p>
<p>We aim to drill into these layers to get a 5 million year record of the monsoon. Drilling these layers will allow us to understand how Australia’s climate and the Australian monsoon behaved during the last greenhouse period on Earth 3 million to 5 million years ago.</p>
<p>This was when the CO<sub>2</sub> levels in the atmosphere were more than 400 parts per million and the Antarctic ice sheet was smaller than today.</p>
<p>As this is the most recent period in Earth history when CO<sub>2</sub> levels were similar to today’s, our research should lead to a better understanding of the possible response of Australian monsoonal and arid areas to future climate change.</p>
<p>Our two month ocean expedition should hopefully lead to a greater understanding of Australia’s present tropical environment. How this environment behaved in the distant past, millions of years ago. How it came to be as it is today and how it might behave in future.</p>
<p>So we are in effect digging deep into our past to see our future.</p><img src="https://counter.theconversation.com/content/43544/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Stephen Gallagher receives funding from the Australian Research Council and is a Chief Investigator on an ARC LIEF grant that funds Australia's membership to the International Ocean Discovery Program (IODP)</span></em></p>Scientists are about to embark on a two month mission to find out how Australia and its reefs coped with climate change in the past, and therefore how it should cope with any future change.Stephen Gallagher, Associate Professor, The University of MelbourneLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/291332014-07-21T05:10:32Z2014-07-21T05:10:32ZIndia is missing its monsoon, and El Niño could be the culprit<figure><img src="https://images.theconversation.com/files/53912/original/vcvy6y38-1405431101.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The monsoon can dampen spirits, whether it rains too much or not enough.</span> <span class="attribution"><a class="source" href="http://commons.wikimedia.org/wiki/File:Monsoon_couple_on_motorcycle.jpg">Arvind Jain</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>With each monsoon season India waits with bated breath for forecasts from the <a href="http://www.imd.gov.in/section/nhac/dynamic/Monsoon_frame.htm">India Meteorological Department</a> and other international forecasting agencies. This year’s forecast suggested a weakened monsoon, and sure enough for five weeks the monsoon has failed to provide the deluge that is expected. </p>
<p>For India, the monsoon rains typically last from June to September and contribute a whopping 80% of the annual rainfall total. Indian society is therefore finely tuned to the monsoon for its agriculture, industry and water supply for drinking and sanitation. If spread evenly over the whole country, the total rainfall during summer amounts to around 850mm. This year has seen <a href="http://in.reuters.com/article/2014/07/03/india-monsoon-idINKBN0F819X20140703">a substantial deficit so far</a>, currently standing at about <a href="http://www.tropmet.res.in/%7Ekolli/MOL/Monsoon/year2014/daily_2014.html">37% below normal</a> and close to the <a href="http://www.tropmet.res.in/%7Ekolli/MOL/Monsoon/year2009/daily_2009.html">large deficit in experienced in 2009</a>, which was, like 2002 before it, a year of substantial drought, bringing reduced crop yields and hitting the country’s whole economy.</p>
<p>Now in mid-July, the forecast looks set to improve. The monsoons’ advance northwards across the country has been particularly slow, leading to lack of water for agriculture and prolonged heatwave conditions – in Delhi a week or so ago I experienced temperatures near 40°C due to the absence of rain. In some regions, farmers have had to plant alternative crops that require less water due to the lack of rain, and authorities have <a href="http://articles.economictimes.indiatimes.com/2014-07-14/news/51484578_1_monsoon-deficit-drought-year-cent-rain-deficit">diverted irrigation to drinking water</a>, exacerbating their problems.</p>
<h2>Anatomy of the monsoon</h2>
<p>The monsoons are the biggest manifestation of the effects of the annual seasonal cycle on the planet’s weather. During spring and summer, the difference between the rapid warming of the Earth’s surface and the slower warming of the nearby ocean generates a tropospheric temperature gradient – a strong gradient in air temperature from north to south of the equator, seen in South Asia most strongly over northern India and the Tibetan Plateau. This temperature gradient stretches far up into the atmosphere forming a difference in pressure, stretching from high pressure over the southern Indian Ocean to low pressure over India. The result of this pressure gradient is the seasonal winds we know as the monsoon, which carry moisture to supply the monsoon rains across Asia.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/53911/original/w6kgzz4c-1405430980.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/53911/original/w6kgzz4c-1405430980.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/53911/original/w6kgzz4c-1405430980.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/53911/original/w6kgzz4c-1405430980.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/53911/original/w6kgzz4c-1405430980.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/53911/original/w6kgzz4c-1405430980.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/53911/original/w6kgzz4c-1405430980.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">Storm clouds coming.</span>
<span class="attribution"><a class="source" href="http://commons.wikimedia.org/wiki/File:Monsoon_clouds_near_Nagercoil.jpg">PlaneMad</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>The onset of the monsoon rains typically comes at the beginning of June, with the weather front stretching from the southwest Indian state of Kerala across the ocean to cover the states in the far northeast of India. For Indian society, and especially farmers, knowing about any variation in the intensity and duration of the monsoon and when it will start is vital. The progression of the monsoon across the country normally takes around six weeks, reaching the border of India and Pakistan by around mid-July. In September, the monsoon withdraws in the opposite direction, and as a result northwest regions experience a much shorter monsoon season and consequently greater pressure on water resources.</p>
<h2>Change is coming</h2>
<p>So why has it been happening? While a full study won’t be carried out until after the season, it is likely that it relates to <a href="http://www.elnino.noaa.gov/">El Niño</a> – a warming of the central-to-east Pacific Ocean along the equator that happens every few years, changing seasonal weather patterns in many parts of the world but particularly around Indian and Pacific Ocean regions. </p>
<p>For India, El Niño is generally associated with monsoon drought. The remote interaction with the monsoon (known as <a href="http://www.met.rdg.ac.uk/phdtheses/Behaviour%20of%20the%20monsoon-ENSO%20system%20in%20current%20and%20future%20climates%20of%20a%20general%20circulation%20model.pdf">teleconnection</a>) is caused by a disruption to the normal trade winds in the Pacific and Indian Oceans, known as the <a href="http://www3.geosc.psu.edu/courses/Geosc320/Lau.pdf">Walker Circulation</a> after Sir Gilbert Walker, a British meteorologist in India who sought to predict when the monsoon would fail.</p>
<p>Rising air and enhanced rainfall meet over the warm ocean surface during El Niño, much further east than Indonesia as is usual. But what goes up must come down, and these shifts in the circulation lead to descending air over India, which reduces the strength of the monsoon. Research has also established that <a href="http://dx.doi.org/doi:10.1002/qj.45">El Niño can delay the monsoon’s onset</a>, shortening the duration of rains over India. </p>
<p>A major concern is that the monsoon will be changed by global warming. However, all the <a href="http://climatica.org.uk/ipcc-special-future-climate-phenomena-regional-climate-change">indications from our climate models</a> are that the Indian monsoon will continue to supply the region with strong seasonal rainfall. In fact most suggest that <a href="http://dx.doi.org/doi:10.1038/nclimate1495">greater concentrations of atmospheric carbon dioxide will bring more, rather than less, rain</a>. So far, so good – but the monsoon’s rains are not a statistical average spread equally on each day and in each location. Model simulations also suggest that tropical rainfall will tend to be heavier when it occurs, with potentially longer dry periods between rain events. Both of these factors have important implications for water resources, including crop damage as well as increased flooding.</p>
<p>With El Niño conditions forecast to grow in the Pacific throughout the rest of 2014, the full impact on this summer’s monsoon will depend on if the forecast comes true and the location of where El Niño occurs. What we can’t yet say with any certainty is how El Niño’s link to and effect on the monsoon will change under warmer future climate conditions – we only know that greater extremes of variability are likely, and a more variable monsoon may be a problem.</p><img src="https://counter.theconversation.com/content/29133/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Andrew Turner receives funding from the UK Natural Environment Research Council and the India Ministry of Earth Sciences.</span></em></p>With each monsoon season India waits with bated breath for forecasts from the India Meteorological Department and other international forecasting agencies. This year’s forecast suggested a weakened monsoon…Andrew Turner, Lecturer in Monsoon Systems, University of ReadingLicensed as Creative Commons – attribution, no derivatives.