tag:theconversation.com,2011:/es/topics/oceanography-8594/articlesOceanography – The Conversation2024-02-14T03:56:08Ztag:theconversation.com,2011:article/2233222024-02-14T03:56:08Z2024-02-14T03:56:08ZThe world’s coral reefs are bigger than we thought – but it took satellites, snorkels and machine learning to see them<figure><img src="https://images.theconversation.com/files/575519/original/file-20240214-20-mjiqz2.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C4607%2C2592&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/aerial-view-great-barrier-reef-whitsundays-1496224889">Shutterstock</a></span></figcaption></figure><p>The world’s coral reefs are close to 25% larger than we thought. By using satellite images, machine learning and on-ground knowledge from a global network of people living and working on coral reefs, <a href="https://www.sciencedirect.com/science/article/pii/S2949790624000016?via%3Dihub">we found</a> an extra 64,000 square kilometres of coral reefs – an area the size of Ireland. </p>
<p>That brings the total size of the planet’s shallow reefs (meaning 0-20 metres deep) to 348,000 square kilometres – the size of Germany. This figure represents whole coral reef ecosystems, ranging from sandy-bottomed lagoons with a little coral, to coral rubble flats, to living walls of coral. </p>
<p>Within this 348,000 km² of coral is 80,000 km² where there’s a hard bottom – rocks rather than sand. These areas are likely to be home to significant amounts of coral – the places snorkellers and scuba divers most like to visit. </p>
<p>You might wonder why we’re finding this out now. Didn’t we already know where the world’s reefs are? </p>
<p>Previously, we’ve had to pull data from many different sources, which made it harder to pin down the extent of coral reefs with certainty. But now we have high resolution satellite data covering the entire world – and are able to see reefs as deep as 30 metres down. </p>
<p>We coupled this with direct observations and records of coral reefs from over <a href="https://allencoralatlas.org/attribution">400 individuals and organisations</a> in countries with coral reefs from all regions, such as the Maldives, Cuba and Australia. </p>
<p>To produce the maps, we used machine learning techniques to chew through 100 trillion pixels from the Sentinel-2 and Planet Dove CubeSat satellites to make accurate predictions about where coral is – and is not. The team worked with almost 500 researchers and collaborators to make the maps. </p>
<p>The result: the world’s first comprehensive map of coral reefs extent, and their composition, produced through the <a href="https://allencoralatlas.org/">Allen Coral Atlas</a>. </p>
<p>The maps are already proving their worth. Reef management agencies around the world are using them to plan and assess conservation work and threats to reefs. </p>
<figure class="align-center ">
<img alt="Researcher towing a GPS on Great Barrier Reef during an expedition." src="https://images.theconversation.com/files/575477/original/file-20240213-26-wxc8ic.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/575477/original/file-20240213-26-wxc8ic.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/575477/original/file-20240213-26-wxc8ic.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/575477/original/file-20240213-26-wxc8ic.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/575477/original/file-20240213-26-wxc8ic.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/575477/original/file-20240213-26-wxc8ic.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/575477/original/file-20240213-26-wxc8ic.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">We combined satellite data with real world observations. Here, Dr Eva Kovacs tows a GPS on the Great Barrier Reef.</span>
<span class="attribution"><a class="source" href="https://allencoralatlas.org/blog/meet-the-team-university-of-queensland/">Allan Coral Atlas</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<h2>Where is this hidden coral?</h2>
<p>You can see the difference for yourself. In the interactive slider below, red indicates the newly detected coral in reefs off far north Queensland. </p>
<p><iframe id="tc-infographic-1015" class="tc-infographic" height="400px" src="https://cdn.theconversation.com/infographics/1015/df887cb0211a347030b52f7e8261bcacbc7e9463/site/index.html" width="100%" style="border: none" frameborder="0"></iframe></p>
<p>This infographic shows the new detail we now have for the Tongue Reef, in the seas off Port Douglas in Far North Queensland. </p>
<p><iframe id="tc-infographic-1017" class="tc-infographic" height="400px" src="https://cdn.theconversation.com/infographics/1017/21ab9e743c8e2a3a716df327b0946c4bf8e47468/site/index.html" width="100%" style="border: none" frameborder="0"></iframe></p>
<p>Our maps have three levels of detail. The first is the most expansive – the entire coral reef ecosystem. Seen from space, it has light areas of coral fringed by darker deeper water. </p>
<p>Then we have geomorphic detail, meaning what the areas within the reef look like. This includes sandy lagoons, reef crests exposed to the air at low tide, sloping areas going into deeper water and so on.</p>
<p><iframe id="tc-infographic-1016" class="tc-infographic" height="400px" src="https://cdn.theconversation.com/infographics/1016/ba3212ee64a358a16ca6b5ccfb454b415a72afe1/site/index.html" width="100%" style="border: none" frameborder="0"></iframe></p>
<p>And finally we have fine detail of the benthic substrates, showing where you have areas dominated by coral cover. </p>
<p>Coral can’t grow on sand. Polyps have to attach to a hard surface such as rock before they can begin expanding the reef out of their limestone-secreting bodies. </p>
<p>Some of our maps include fine detail of benthic substrates, meaning where coral is most likely to be and the substrates (seafloor) available to the polyps, such as existing coral, sand, rubble, or seagrass. </p>
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<p>It’s a crucial time for the world’s coral reefs. We’re discovering the full extent of shallow water reefs – while other researchers are finding large new <a href="https://www.theguardian.com/environment/2024/jan/19/deep-sea-coral-reef-atlantic-coast">black coral reefs</a> in deeper water. </p>
<p>But even as we make these discoveries, coral reefs are reeling. Climate change is steadily heating up the sea and making it more acidic. Coral polyps can’t <a href="https://theconversation.com/the-heroic-effort-to-save-floridas-coral-reef-from-extreme-ocean-heat-as-corals-bleach-across-the-caribbean-210974">handle too much heat</a>. These wonders of biodiversity are home to a quarter of the ocean’s species.</p>
<figure class="align-center ">
<img alt="Scientist doing coral reef research." src="https://images.theconversation.com/files/575481/original/file-20240213-20-h7bnsp.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/575481/original/file-20240213-20-h7bnsp.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/575481/original/file-20240213-20-h7bnsp.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/575481/original/file-20240213-20-h7bnsp.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/575481/original/file-20240213-20-h7bnsp.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=423&fit=crop&dpr=1 754w, https://images.theconversation.com/files/575481/original/file-20240213-20-h7bnsp.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=423&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/575481/original/file-20240213-20-h7bnsp.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=423&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Making these maps took plenty of underwater research as well as satellite data. This photo shows Dr Chris Roelfsema conducting a photo transect in a remote area of the Great Barrier Reef.</span>
<span class="attribution"><a class="source" href="https://allencoralatlas.org/blog/new-funds-for-coral-reef-field-engagement/">Allen Coral Atlas</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>In good news, these maps are already leading to real world change. We’ve already seen new efforts to conserve coral reefs in Indonesia, several Pacific island nations, Panama, Belize, Kenya and Australia, among others. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-do-coral-reefs-thrive-in-parts-of-the-ocean-that-are-low-in-nutrients-by-eating-their-algal-companions-212049">How do coral reefs thrive in parts of the ocean that are low in nutrients? By eating their algal companions</a>
</strong>
</em>
</p>
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<img src="https://counter.theconversation.com/content/223322/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Mitchell Lyons receives funding from Australian Research Council and Australian Commonwealth Government. Mitchell Lyons works for the University of Queensland and the University of New South Wales. </span></em></p><p class="fine-print"><em><span>Stuart Phinn receives funding from the Australian Research Council, Queensland and New South Wales state governments, Geoscience Australia and other Commonwealth agencies, and SmartSAT CRC. He works for the University of Queensland and was the founding director of Earth Observation Australia and Australia's Terrestrial Ecosystem Research Network (TERN). </span></em></p>Our new maps show coral reefs are more extensive than we thought.Mitchell Lyons, Postdoctoral research fellow, The University of QueenslandStuart Phinn, Professor of Geography, Director - Remote Sensing Research Centre, Chair - Earth Observation Australia, The University of QueenslandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2163302023-11-15T13:22:37Z2023-11-15T13:22:37ZAs the US begins to build offshore wind farms, scientists say many questions remain about impacts on the oceans and marine life<figure><img src="https://images.theconversation.com/files/558700/original/file-20231109-19-jiiump.jpg?ixlib=rb-1.1.0&rect=0%2C7%2C5020%2C2988&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A row of monopiles that will be the base for offshore wind turbines, in the Atlantic Ocean off the coast of Martha's Vineyard, Mass. </span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/new-bedford-ma-a-row-of-mono-piles-that-will-be-the-base-news-photo/1623091024">David L Ryan/The Boston Globe via Getty Images</a></span></figcaption></figure><p><em>As renewable energy production expands across the U.S., the environmental impacts of these new sources are receiving increased attention. In a <a href="https://nap.nationalacademies.org/catalog/27154/potential-hydrodynamic-impacts-of-offshore-wind-energy-on-nantucket-shoals-regional-ecology">recent report</a>, the National Academies of Sciences, Engineering, and Medicine examined whether and how constructing offshore wind farms in the Nantucket Shoals region, southeast of Massachusetts, could affect critically endangered North Atlantic right whales. The Conversation asked marine scientists <a href="https://scholar.google.com/citations?user=VRlWQ7QAAAAJ&hl=en">Erin L. Meyer-Gutbrod</a>, <a href="https://scholar.google.com/citations?user=_GGEmncAAAAJ&hl=en">Douglas Nowacek</a>, <a href="https://scholar.google.com/citations?user=U7NE0fUAAAAJ&hl=en">Eileen E. Hofmann</a> and <a href="https://www.researchgate.net/profile/Josh-Kohut">Josh Kohut</a>, all of whom served on the study committee, to explain the report’s key findings.</em></p>
<h2>Why did this study focus on such a specific site?</h2>
<p>The <a href="https://www.boem.gov/">Bureau of Ocean Energy Management</a>, which is part of the U.S. Department of the Interior and regulates offshore energy production, asked the National Academies to conduct this study. Regulators wanted to better understand how installing and operating offshore, fixed-bottom wind turbine generators would affect physical oceanographic processes, such as tides, waves and currents, and in turn how those changes could affect the ecosystem. </p>
<p>For example, offshore wind turbines decrease wind speeds behind them, and the presence of their structures makes the water more turbulent. These changes could affect ocean currents, surface wind speeds and other factors that influence <a href="https://www.allthescience.org/what-is-hydrodynamics.htm">hydrodynamics</a> – the structure and movement of the water around the turbines.</p>
<p>The <a href="https://dbpedia.org/page/Nantucket_Shoals">Nantucket Shoals</a> region is a large, shallow area in the Atlantic that extends south of Cape Cod. Our report focused on it because this is the first large-scale offshore wind farm area in the U.S., and the region has been included in several recent hydrodynamic modeling studies.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/559409/original/file-20231114-23-1q60k9.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Map showing nine offshore leasing areas near Nantucket Shoals" src="https://images.theconversation.com/files/559409/original/file-20231114-23-1q60k9.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/559409/original/file-20231114-23-1q60k9.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=540&fit=crop&dpr=1 600w, https://images.theconversation.com/files/559409/original/file-20231114-23-1q60k9.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=540&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/559409/original/file-20231114-23-1q60k9.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=540&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/559409/original/file-20231114-23-1q60k9.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=679&fit=crop&dpr=1 754w, https://images.theconversation.com/files/559409/original/file-20231114-23-1q60k9.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=679&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/559409/original/file-20231114-23-1q60k9.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=679&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Map of the Nantucket Shoals region, showing current wind-power lease areas (colored zones) and water depth contours (red and white lines) in meters.</span>
<span class="attribution"><a class="source" href="https://nap.nationalacademies.org/read/27154/chapter/2">NASEM 2023</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Why are North Atlantic right whales of special concern?</h2>
<p>North Atlantic right whales <a href="https://www.fisheries.noaa.gov/species/north-atlantic-right-whale">are critically endangered</a>. Scientists estimate that the population is down to <a href="https://www.fisheries.noaa.gov/s3/2023-10/TM314-508-0.pdf">just 356 animals</a>. </p>
<p>This species was <a href="https://www.fisheries.noaa.gov/species/north-atlantic-right-whale">almost driven to extinction</a> after centuries of commercial whaling. Even though the whales have been protected from whaling for almost 100 years, they are still accidentally killed when they are <a href="https://www.fisheries.noaa.gov/national/endangered-species-conservation/reducing-vessel-strikes-north-atlantic-right-whales">hit by vessels</a> or <a href="https://doi.org/10.1111/csp2.12736">become entangled in fishing gear</a>. These two sources of mortality are responsible for most documented juvenile and adult right whale <a href="https://doi.org/10.25923/42zk-w456">deaths over the past 25 years</a>. </p>
<p>There are options for protecting them, such as <a href="https://www.fisheries.noaa.gov/feature-story/rule-amend-north-atlantic-right-whale-vessel-speed-regulations-closed-comment">slowing or rerouting boats</a>, shortening the fishing season or even <a href="https://theconversation.com/high-tech-fishing-gear-could-help-save-critically-endangered-right-whales-115974">modifying fishing gear</a> to make it more whale-safe. However, regulators need to know where the whales are going to be and when they’ll be there, so they can put those protections in place. </p>
<p>It’s usually hard to figure out where whales are – they have a large habitat and spend most of their time below the surface of the water, where observers can’t see them. Recently it’s gotten even harder, because climate change is causing whales to <a href="https://doi.org/10.5670/oceanog.2021.308">shift where and when they feed</a>. </p>
<p>Currently, right whales are <a href="https://doi.org/10.1038/s41598-022-16200-8">spending more time around the Nantucket Shoals region</a>. This means scientists and managers need to make sure that wind energy development in the area is happening safely and that threats to whales in the area are reduced.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/6Pjj094pfCQ?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">North Atlantic right whales are critically endangered, mainly by boat strikes and entanglement in fishing gear.</span></figcaption>
</figure>
<h2>How might offshore wind farms affect right whales in the study area?</h2>
<p>Right whales are filter feeders that consume huge quantities of <a href="https://eol.org/pages/46532540/articles">tiny zooplankton</a>. The whales need to find large, dense patches of zooplankton at appropriate water depths in order to feed. Altering waves, tides and currents in ways that affect where their prey are located could affect whale feeding or cause the whales to change foraging habitats. </p>
<p>We concluded that it is critical to consistently monitor right whales and their prey within and outside the region, because we don’t know whether wind development will cause an increase, a decrease or no change to their zooplankton prey. Consistent monitoring will allow managers to mitigate potential negative impacts on the whales.</p>
<p>Researchers will need to collect data during all phases of wind farm construction and operation and develop robust models to determine whether wind farms will affect prey availability for right whales in the study area. Even once they do this research, it will still be difficult to isolate potential impacts from wind farms. </p>
<p>There is a tremendous amount of both natural and human-driven variability and change in this region, including tides, seasonal changes in water temperature and long-term ocean warming driven by climate change. <a href="https://doi.org/10.1002/lno.12242">Climate-driven shifts in prey in distant regions</a>, such as the <a href="https://www.britannica.com/place/Bay-of-Fundy">Bay of Fundy</a> or the <a href="https://www.britannica.com/place/Gulf-of-Saint-Lawrence">Gulf of St. Lawrence</a>, may also change how right whales use the Nantucket Shoals region. </p>
<p>Development of the first wind energy farms in the Nantucket Shoals region is a valuable opportunity to better understand hydrodynamic impacts of turbines on marine ecosystems. We expect that it will help guide future development of wind farms along the U.S. East Coast. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/558703/original/file-20231109-29-vwzt46.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Map showing offshore wind energy potential along U.S. coastlines." src="https://images.theconversation.com/files/558703/original/file-20231109-29-vwzt46.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/558703/original/file-20231109-29-vwzt46.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=355&fit=crop&dpr=1 600w, https://images.theconversation.com/files/558703/original/file-20231109-29-vwzt46.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=355&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/558703/original/file-20231109-29-vwzt46.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=355&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/558703/original/file-20231109-29-vwzt46.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=446&fit=crop&dpr=1 754w, https://images.theconversation.com/files/558703/original/file-20231109-29-vwzt46.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=446&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/558703/original/file-20231109-29-vwzt46.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=446&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A 2022 assessment by the National Renewable Energy Laboratory estimated that fixed-bottom and floating offshore wind turbines could generate enough energy to cover three times the annual electricity consumption in the U.S.</span>
<span class="attribution"><a class="source" href="https://www.nrel.gov/wind/offshore-resource.html">NREL</a></span>
</figcaption>
</figure>
<h2>What are the most important knowledge gaps?</h2>
<p>Few studies have been done to understand hydrodynamics around wind energy turbines, and those that exist focus on European offshore wind farms in the North Sea, where conditions are different from Nantucket Shoals. Large turbines of the size planned for the Nantucket Shoals region have not been built yet in U.S. waters. </p>
<p>Researchers have tried to model the hydrodynamic impacts of turbines, but their results don’t always agree with each other. There’s a need for more work to compare different types of models with each other, and with actual observations in the ocean, to make sure that they represent key processes like tides, stratification, turbulence and drag correctly. </p>
<p>The most accurate outputs will likely come from using a range of models. Oceanographers might start with models that predict what happens as water moves past a single turbine. These results then would inform models that predict the effects of an entire wind farm. Then results from wind farm-scale models would be incorporated into models that predict regional ocean circulation.</p>
<p>There are also a lot of knowledge gaps on the biology side, including questions about what species of zooplankton are in the Nantucket Shoals region, where they come from and what makes them aggregate into patches that are dense enough for right whales to eat. Right whale feeding in the Nantucket Shoals region isn’t well understood, so scientists need more observations to determine which zooplankton types are targeted by right whales and where and when the whales feed.</p>
<h2>Does the report call for slowing offshore wind development until these questions are answered?</h2>
<p>No, and we were not asked to provide recommendations for how the wind industry should proceed with construction. </p>
<p>Nantucket Shoals is one of many regions where large-scale wind farms will be built in U.S. waters over the coming decades. Our committee advised federal regulators and other relevant organizations to conduct observational and modeling research to better understand hydrodynamic and ecological processes before, during and after wind farm construction. These studies will be critical for understanding and addressing environmental impacts from offshore wind farm development.</p>
<p><em>Richard Merrick, former chief science adviser and director of scientific programs at National Oceanic and Atmospheric Administration Fisheries, and Kelly Oskvig, National Academies of Sciences, Engineering, and Medicine director of the study described here, contributed to this article.</em></p><img src="https://counter.theconversation.com/content/216330/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Erin L. Meyer-Gutbrod receives funding from the Bureau of Ocean Energy Management. She serves as a volunteer on the Marine Mammal Subcommittee of the Regional Wildlife Science Collaborative for Offshore Wind.</span></em></p><p class="fine-print"><em><span>Douglas Nowacek receives funding from the U.S. Department of Energy and the Bureau of Ocean Energy Management.</span></em></p><p class="fine-print"><em><span>Eileen E. Hofmann receives funding from the Bureau of Ocean Energy Management. </span></em></p><p class="fine-print"><em><span>Josh Kohut receives funding from the U.S. Department of Energy. He serves as a volunteer member of the board of directors for the Marine Technology Society. </span></em></p>A recent study focusing on how offshore wind farms in Massachusetts waters could affect endangered right whales does not call for slowing the projects, but says monitoring will be critical.Erin L. Meyer-Gutbrod, Assistant Professor of Earth, Ocean & Environment, University of South CarolinaDouglas Nowacek, Professor of Conservation Technology in Environment and Engineering, Duke UniversityEileen E. Hofmann, Professor of Oceanography, Old Dominion UniversityJosh Kohut, Professor of Marine and Coastal Sciences, Rutgers UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2149622023-10-06T04:19:38Z2023-10-06T04:19:38ZClimate change is disrupting ocean currents. We’re using satellites and ships to understand how<figure><img src="https://images.theconversation.com/files/552445/original/file-20231006-27-b8rch3.jpeg?ixlib=rb-1.1.0&rect=51%2C0%2C6809%2C3939&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.jpl.nasa.gov/images/pia25595-swot-in-orbit-illustration">CNES</a></span></figcaption></figure><p>Earth’s ocean is incredibly vast. Some parts of it are <a href="https://www.theguardian.com/environment/shortcuts/2018/may/18/point-nemo-is-the-most-remote-oceanic-spot-yet-its-still-awash-with-plastic">so remote</a> that the nearest human habitation is the International Space Station.</p>
<p>As the world warms, what happens in the ocean – and what happens <em>to</em> the ocean – will be vital to all our lives. But to monitor what’s happening in remote waters, we need to study the ocean from space.</p>
<p>Late last year, NASA and CNES, the French space agency, launched a satellite that promises to give scientists a far better view than ever before of the ocean’s surface. The <a href="https://swot.jpl.nasa.gov/">Surface Water and Ocean Topography (SWOT)</a> mission will reveal ocean currents that play a crucial role in the weather and climate.</p>
<p>To make the most of the satellite observations, we need to compare them with measurements made at surface level. That is why we are heading out to sea on the state-of-the-art CSIRO research vessel <a href="https://mnf.csiro.au/en/RV-Investigator">RV Investigator</a> to gather essential ocean data under the satellite’s path as it orbits Earth. </p>
<h2>Current affairs</h2>
<p>Climate change is disrupting the global network of currents that connect the oceans. Researchers have <a href="https://theconversation.com/torrents-of-antarctic-meltwater-are-slowing-the-currents-that-drive-our-vital-ocean-overturning-and-threaten-its-collapse-202108">detected a slowdown</a> of the deep “overturning circulation” that carries carbon, heat, oxygen and nutrients from Antarctica around the globe. Meanwhile, at the surface, ocean currents are <a href="https://theconversation.com/satellites-reveal-ocean-currents-are-getting-stronger-with-potentially-significant-implications-for-climate-change-159461">becoming more energetic</a>. </p>
<p>We have also seen dramatic changes in fast, narrow rivers of seawater called <a href="https://theconversation.com/shifting-ocean-currents-are-pushing-more-and-more-heat-into-the-southern-hemispheres-cooler-waters-189122">western boundary currents</a>, such as the <a href="https://oceanservice.noaa.gov/facts/gulfstreamspeed.html#:%7E:text=The%20Gulf%20Stream%20is%20an,flowing%20northeast%20across%20the%20Atlantic">Gulf Stream</a> and the <a href="https://theconversation.com/can-you-surf-the-east-australian-current-finding-nemo-style-27392">East Australian Current</a>. </p>
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Read more:
<a href="https://theconversation.com/shifting-ocean-currents-are-pushing-more-and-more-heat-into-the-southern-hemispheres-cooler-waters-189122">Shifting ocean currents are pushing more and more heat into the Southern Hemisphere’s cooler waters</a>
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<p>These currents funnel heat from the tropics towards the poles, and in recent decades they have become hotspots for ocean warming. In the Southern Hemisphere, they are <a href="https://www.nature.com/articles/nclimate1353">warming two to three times faster</a> than the global average.</p>
<p>As these currents destabilise, they <a href="https://www.nature.com/articles/nclimate1353">alter how heat is distributed</a> throughout the ocean. This in turn will cause major changes in local weather and marine ecosystems that may impact the lives of millions of people. </p>
<h2>Playground physics</h2>
<p>The SWOT satellite mission will give researchers a powerful new tool to monitor changes in ocean currents by using accurate satellite measurements of the sea surface – plus a little bit of playground physics. </p>
<p>The satellite carries an instrument that will map variations in the height of the sea surface in unprecedented detail. These variations might be less than a metre in height over horizontal distances of hundreds of kilometres. But oceanographers can use the measurements to estimate ocean currents flowing underneath. </p>
<p>Small variations in the height of the sea surface create horizontal pressure differences that try to push water away from areas of high sea level and towards areas of low sea level. That pressure difference is balanced by the Coriolis force, which gently deflects ocean currents to the right in the Northern Hemisphere and to the left in the Southern Hemisphere. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/552426/original/file-20231005-17-76igp5.jpg?ixlib=rb-1.1.0&rect=7%2C0%2C1270%2C718&q=45&auto=format&w=1000&fit=clip"><img alt="Illlustration showing Earth from space with the ocean filled with complex whorls of current" src="https://images.theconversation.com/files/552426/original/file-20231005-17-76igp5.jpg?ixlib=rb-1.1.0&rect=7%2C0%2C1270%2C718&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/552426/original/file-20231005-17-76igp5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/552426/original/file-20231005-17-76igp5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/552426/original/file-20231005-17-76igp5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/552426/original/file-20231005-17-76igp5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/552426/original/file-20231005-17-76igp5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/552426/original/file-20231005-17-76igp5.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>
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<span class="caption">Earth’s oceans are filled with complex network of currents driven by the rotation of the planet.</span>
<span class="attribution"><span class="source">NASA / Goddard Space Flight Center Scientific Visualization Studio</span></span>
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<p>You can experience the Coriolis force at the playground. Step onto a merry-go-round and ask a friend to stand on the opposite side from you. As you start spinning, toss a ball to your friend. You will notice that the ball appears to be <a href="https://www.youtube.com/watch?v=mPsLanVS1Q8&ab_channel=NationalGeographic">deflected away</a> from the direction of rotation. </p>
<p>In reality, the ball has moved in a straight line; your friend has simply moved away from where you were aiming. But, to you both, the ball seems to have been deflected by an invisible “pseudo-force” – the Coriolis force. </p>
<p>Now imagine the merry-go-round is Earth, and the ball is an ocean current. The Coriolis deflection is enough to balance pressure differences across hundreds of kilometres and causes seawater to flow in ocean currents. </p>
<h2>Science at sea</h2>
<p>By carefully measuring the height of the sea surface and using our knowledge of the Coriolis force, oceanographers will be able to use data from NASA’s satellite to reveal ocean currents in greater detail than ever before. But to make sense of that data, researchers need to compare satellite measurements with observations made down here on Earth. </p>
<p>That’s why we are <a href="https://www.smh.com.au/national/nsw/underwater-cyclones-off-sydney-are-giant-floating-laboratory-s-next-mission-20231005-p5ea0q.html">leading a voyage</a> of more than 60 scientists, support staff and crew aboard the <a href="https://mnf.csiro.au/en/RV-Investigator">RV Investigator</a>, Australia’s national flagship for blue water ocean research.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/552440/original/file-20231006-19-o6ad33.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Photo of a blue-and-white ship, the RV Investigator, sailing through the sea beneath grey skies." src="https://images.theconversation.com/files/552440/original/file-20231006-19-o6ad33.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/552440/original/file-20231006-19-o6ad33.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/552440/original/file-20231006-19-o6ad33.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/552440/original/file-20231006-19-o6ad33.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/552440/original/file-20231006-19-o6ad33.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/552440/original/file-20231006-19-o6ad33.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/552440/original/file-20231006-19-o6ad33.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A 24-day voyage aboard the RV Investigator will gather data about oceans currents.</span>
<span class="attribution"><span class="source">CSIRO</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
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<p>Our 24-day voyage will study ocean dynamics off Australia’s southeast coast using the Investigator’s world-class scientific equipment, including satellite-tracked floating buoys and drifters that will be used to measure the real-time movement of currents at the ocean surface. </p>
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Read more:
<a href="https://theconversation.com/explainer-the-rv-investigators-role-in-marine-science-35239">Explainer: the RV Investigator’s role in marine science</a>
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<p>The voyage is part of a <a href="https://www.swot-adac.org/">huge collaboration</a> by scientists around the world to gather observational data under the satellite’s path as it orbits Earth. This data will help validate satellite measurements and improve weather forecasts, including those from Australia’s Bureau of Meteorology, and assist with climate risk assessment and prediction.</p>
<p>We hope to better understand how our oceans are changing using what we observe in space, at sea — and in the playground. </p>
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<p><em>This research is supported by a grant of sea time on RV Investigator from the CSIRO Marine National Facility.</em></p>
<p><em>You can follow our voyage on <a href="https://twitter.com/hashtag/RVInvestigator?src=hashtag_click">Twitter/X</a> using the hashtag</em> #RVInvestigator.</p><img src="https://counter.theconversation.com/content/214962/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Shane Keating receives funding from the Australian Research Council. </span></em></p><p class="fine-print"><em><span>Moninya Roughan receives funding from Australian Research Council, Australia's Marine National Facility, and the National Collaborative Research Infrastructure Scheme</span></em></p>A sea voyage and a satellite mission will combine to produce a more detailed picture of the ocean’s currents than ever before.Shane Keating, Senior Lecturer in Mathematics and Oceanography, UNSW SydneyMoninya Roughan, Professor in Oceanography, UNSW SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2136782023-10-02T14:37:50Z2023-10-02T14:37:50ZNigeria’s new blue economy ministry could harness marine resources - moving the focus away from oil<p><em>Nigeria’s President Bola Ahmed Tinubu announced a new <a href="https://www.channelstv.com/2023/08/16/full-list-of-ministers-and-portfolios/">ministerial portfolio</a> in August: Marine and Blue Economy. This was <a href="https://dailypost.ng/2023/08/22/long-overdue-creation-of-marine-and-blue-economy-ministry-excites-stakeholders/">welcome news</a> as it renewed hope for economic development outside the oil sector. We asked marine sustainability and blue economy <a href="https://iucn.org/our-union/commissions/group/iucn-ceesp-governance-equity-and-rights-thematic-group">expert</a> Isa Olalekan Elegbede to explain how the ministry could benefit Nigeria.</em></p>
<h2>Why has Nigeria established a new ministry for the blue economy?</h2>
<p>The <a href="https://link.springer.com/referenceworkentry/10.1007/978-3-030-02006-4_401-1">blue economy</a> is the sustainable use of ocean and coastal resources for economic growth. It <a href="https://www.frontiersin.org/articles/10.3389/fmars.2020.00586/full">integrates environmental, social, economic and institutional objectives</a> into the use of marine resources. It <a href="https://blue-economy-observatory.ec.europa.eu/eu-blue-economy-sectors_en">includes a wide range of sectors and resources</a> related to oceans, seas, coasts and waterways.</p>
<p>The ocean economy supports <a href="https://www.oecd.org/ocean/topics/ocean-economy/">90% of global trade</a> and <a href="https://www.worldbank.org/en/topic/oceans-fisheries-and-coastal-economies">provides millions of jobs</a>. It includes shipping, tourism and offshore energy <a href="https://www.weforum.org/agenda/2020/06/human-impact-ocean-economy/">valued at US$24 trillion</a>. </p>
<p>Marine fisheries and reefs, sea grass and mangroves are worth US$6.9 trillion; trade and transport US$5.2 trillion; and coastline productivity and carbon absorption US$12.1 trillion. </p>
<p>Nigeria’s establishment of a Ministry of Marine and Blue Economy is a strategic move. I believe the ministry will tap the country’s rich marine resources as an element of the national economic framework. </p>
<p>Nigeria’s coastline <a href="https://fcwc-fish.org/other-news/nigerian-navy-at-64-a-sustained-fight-against-maritime-crimes">stretches</a> for 420 nautical miles and covers an exclusive economic zone of 200 nautical miles. Its maritime interests span the Gulf of Guinea, covering roughly 574,800 square nautical miles with a 2,874 nautical mile coastline.</p>
<p>Marine resources can be exploited to create jobs and transform Nigeria into a <a href="https://venturesafrica.com/now-that-nigeria-has-created-a-ministry-of-marine-and-blue-economy/">leader in sustainable marine activities</a>. It will help diversify the country’s oil-based economy as well. <a href="https://www.rvo.nl/sites/default/files/2021/07/Blue-Bio-Economy-in-Norway.pdf">Norway</a> is an example of how this has been done successfully.</p>
<h2>What four areas should the ministry focus on?</h2>
<p>Nigeria hopes to generate over <a href="https://punchng.com/what-you-need-to-know-about-ministry-of-marine-and-blue-economy/">US$1.5 trillion annually</a> from exploiting its marine resources. To achieve this, the ministry should do the following:</p>
<ul>
<li><p>Create an inclusive committee for effective collaboration among stakeholders and partners. The committee should include scientists, NGOs, youth and traditional communities. Indigenous peoples, persons with disabilities, and the relevant <a href="https://www.legit.ng/politics/1549451-list-ministries-created-by-president-tinubu-ministers/">federal government agencies</a> should not be left out. The committee should advance beyond the scope of the Expanded Committee on Sustainable Blue Economy in Nigeria inaugurated by the former president Muhammadu Buhari.</p></li>
<li><p>Integrate sustainability into policies and strategies. Policies should prioritise sustainable marine resource use. Strategies should focus on sustainable and ethical harvesting, trading, extraction and tourism. Blue economy personnel, unemployed youths and women should be trained. Improved programmes would foster sustainable practices and raise the sector’s contribution to the country’s gross domestic product. </p></li>
<li><p>Sustain investment in ports, transport systems and storage facilities. The same should apply to research and technology. Aquaculture, offshore energy and marine biotechnology should be advanced to increase efficiency and sustainability. Additionally, remote coastal communities should have <a href="https://www.energy.gov/eere/water/marine-energy-blue-economy">access</a> to resilient and blue renewable energy sources and systems to enhance protection of coastal and ocean resources.</p></li>
<li><p>Check mismanagement. To ensure a sustainable future for all, the government should protect coastal and marine ecosystems. Mismanagement could destabilise the delicate balance of these ecosystems. This is crucial, considering the <a href="https://enveurope.springeropen.com/articles/10.1186/s12302-021-00502-1">intricate relationship between the blue economy and marine habitats</a>. Neglect puts fish resources at risk and endangers vital sectors like maritime transport, energy and fishing. Cooperation and commitment to stewardship are therefore imperative to maintaining the health and productivity of the oceans.</p></li>
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<h2>What benefits will Nigerians feel if these steps are taken?</h2>
<p>Oil is a key revenue source for the country. But it has led to major environmental problems. Harnessing the blue economy could be a game changer for Nigeria.</p>
<p>First, it could create jobs and generate income from fisheries, aquaculture, tourism, shipping and renewable energy. </p>
<p>Second, a blue economy could mitigate environmental damage as it enables the restoration of marine ecosystems. Unlike oil, fisheries are renewable. Nigeria’s oil-rich Niger Delta has experienced severe environmental harm. A shift to greener energy supplies could make a massive difference.</p>
<p>Third, it creates the opportunity to grow the tourism sector. Seychelles and Mauritius are examples of countries that earn foreign exchange from marine exports and tourism. </p>
<p>Fourth, it could help attract investment to Nigeria’s marine infrastructure, fisheries and technology. </p>
<p>Fifth, it could help decrease regional and social inequalities in coastal communities. </p>
<p>Finally, investment in the blue economy could encourage marine biology, oceanography and marine technology research. This could, in turn, lead to global innovations. </p>
<p>Despite competition from more experienced countries in the marine industry, the blue economy offers Nigeria significant potential. Strategic planning, global partnerships and investment can make it a reality.</p><img src="https://counter.theconversation.com/content/213678/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Isa O Elegbede is presently affiliated with the Lagos State University and with many international and local NGOs, such as Geo Blue Planet, IUCN/CEESP/TGER; he is also the president of Sayne Development Foundation and Executive director of Pearlrose Foundation. He has received a fellowship grant from Ocean Frontier institute (OFI) in Canada and several international organisations in the past.</span></em></p>Nigeria’s new marine and blue economy ministry has promise but it must be well run.Isa Olalekan Elegbede, Lecturer, Brandenburg University of Technology Cottbus-SenftenbergLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2119022023-09-04T20:06:03Z2023-09-04T20:06:03ZMarine heatwaves don’t just hit coral reefs. They can cause chaos on the seafloor<figure><img src="https://images.theconversation.com/files/545458/original/file-20230830-15-tabdkd.jpg?ixlib=rb-1.1.0&rect=0%2C407%2C3888%2C2479&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>Most of us know what a heatwave feels like on land – sweltering heat for days. But oceans get heatwaves too. When water temperature goes over a seasonal threshold for five days or more, that’s a marine heatwave. They do their worst damage in summer, when the ocean is already at its warmest, but they can occur any time of year. </p>
<p>Over 90% of the heat trapped by greenhouse gases has <a href="https://climate.nasa.gov/vital-signs/ocean-warming/#:%7E:text=Covering%20more%20than%2070%25%20of,heat%20as%20Earth's%20entire%20atmosphere.">gone into</a> our oceans. So it’s no surprise marine heatwaves are getting much more intense and more frequent. This year has been off the charts. From April this year, the world’s average ocean temperature <a href="https://climatereanalyzer.org/clim/sst_daily/">has been</a> the highest ever recorded. </p>
<p>Since the 1980s, satellites have revolutionised ocean science by making it possible to take daily measurements of ocean temperatures. But satellites watch from above. They can’t see what’s happening below the surface. </p>
<p>Our <a href="https://doi.org/10.1038/s43247-023-00966-4">new research</a> explores what’s happening in deeper waters. It turns out, marine heatwaves aren’t just on the surface. In the most devastating marine heatwaves, heat can penetrate right down to the sea bed. Remarkably, some heatwaves only affect the seafloor. </p>
<h2>Why do deep marine heatwaves matter?</h2>
<p>While we usually only see sea creatures at the surface of the ocean, there’s life all the way down. In the shallower seafloors of the continental shelf – the sunken parts of our continents – live fish, kelp beds, sponges, cold water corals, shellfish and crustaceans. </p>
<p>These shallow oceans are, on average, less than 100 metres deep. When the shelf ends, there’s usually an abrupt slope into the deep ocean, where there are kilometres of water between surface and seabed. </p>
<p>Marine heatwaves are damaging to life in the seas covering the continental shelf. Creatures here are sensitive to extreme temperatures, just like those at the surface. But “extreme” to them is different to what we think of as extreme. If you’re used to water at 12°C, a heatwave of 15°C can be devastating. </p>
<p>When marine heatwaves strike, they can kill. More than a billion sea creatures died during a <a href="https://www.nature.com/articles/s41467-023-36289-3">single heatwave</a> off the coast of the western United States and Canada in 2021. This year, extreme heatwaves have hit large parts of the oceans during the northern summer. </p>
<p>Fish and other creatures that can move do so, heading towards the poles or down deeper in search of cooler water. Those that can’t have to endure it or die. Heatwaves can trigger migration. New species arrive, seeking refuge and can alter the ecosystem. </p>
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Read more:
<a href="https://theconversation.com/an-extreme-heatwave-has-hit-the-seas-around-the-uk-and-ireland-heres-whats-going-on-208052">An 'extreme' heatwave has hit the seas around the UK and Ireland – here's what's going on</a>
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<h2>We don’t know much about deeper marine heatwaves</h2>
<p>The seas covering the continental shelf are relatively shallow compared to the kilometres of water in the deep oceans. But even so, it’s impossible to see what’s going on below using satellites or <a href="https://imos.org.au/facilities/oceanradar">high-frequency radar</a>. </p>
<p>The sea is a hostile environment. Instruments are subject to high pressure, corrosive salt water and marine organisms like oysters and sponges settling on them. This is one reason why we only have very limited data on long-term trends in temperatures under the surface. But these records are vital to calculate typical temperatures for the time of year and to figure out what constitutes an extreme. </p>
<p>Australia is one of the few places generating this kind of valuable data long-term. Off the coast of the southeast lie many oceanographic moorings – a floating <a href="https://imos.org.au/facilities/nationalmooringnetwork/">collection of sensors</a> anchored to the bottom. One of these has been measuring daily temperatures from the surface to the seafloor 65 metres down since 1993. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/545276/original/file-20230829-19-lqlw60.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="oceanographic instrument" src="https://images.theconversation.com/files/545276/original/file-20230829-19-lqlw60.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/545276/original/file-20230829-19-lqlw60.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=853&fit=crop&dpr=1 600w, https://images.theconversation.com/files/545276/original/file-20230829-19-lqlw60.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=853&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/545276/original/file-20230829-19-lqlw60.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=853&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/545276/original/file-20230829-19-lqlw60.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1072&fit=crop&dpr=1 754w, https://images.theconversation.com/files/545276/original/file-20230829-19-lqlw60.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1072&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/545276/original/file-20230829-19-lqlw60.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1072&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">In addition to coastal moorings, this oceanographic instrument also measures temperature and salinity of the ocean.</span>
<span class="attribution"><span class="source">Amandine Schaeffer</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Our earlier research found marine heatwaves at depth can actually be <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2017GL073714">more intense</a> and <a href="https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2021GL094785">last longer</a> compared to the surface. But why? </p>
<p>In our new research, we looked at the temperature data closely. We found marine heatwaves come in a variety of types and have different causes. We also found some types of marine heatwave are more likely during particular seasons. </p>
<p>For instance, winter marine heatwaves often run from surface to seafloor. They occur when the powerful, deep and warm East Australian Current snakes westward towards the coast. As the current swings over the continental slope, it drags warm water over the shelf and close to the coast. </p>
<p>In summer, Australia gets two very different types of heatwave in our oceans. The first occur when we get blue-sky weather. With few clouds, more heat from the sun gets into the oceans. They can also occur when there are weaker winds and less ocean cooling from evaporation. These heatwaves are confined to the surface and a few metres below. </p>
<p>Then there’s the second, a very weird heatwave system that only appears close to the seafloor. These are produced when strong wind creates currents driving warm, shallower water down to the bottom. On the east coast, these currents come from cold winds from the south. So even while you’re shivering through cold winds from the Southern Ocean, the ocean seafloor may be sweltering through a heatwave. These may be the most destructive to ecosystems but go all but unnoticed. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/545589/original/file-20230830-27-bfa28q.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="schematic of different marine heatwaves" src="https://images.theconversation.com/files/545589/original/file-20230830-27-bfa28q.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/545589/original/file-20230830-27-bfa28q.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=459&fit=crop&dpr=1 600w, https://images.theconversation.com/files/545589/original/file-20230830-27-bfa28q.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=459&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/545589/original/file-20230830-27-bfa28q.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=459&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/545589/original/file-20230830-27-bfa28q.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=576&fit=crop&dpr=1 754w, https://images.theconversation.com/files/545589/original/file-20230830-27-bfa28q.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=576&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/545589/original/file-20230830-27-bfa28q.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=576&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">This figure shows the different types of marine heatwaves affecting coastal waters (shown by the anomalous heat in red)</span>
<span class="attribution"><span class="source">Author provided</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Marine heatwaves are not created equally</h2>
<p>Our research has shown marine heatwaves come in different flavours. That matters, because it will allow us to get better at predicting if a heatwave is about to strike our oceans. And it will let us anticipate which parts of the water column are about to be hit, and which ecosystems. </p>
<p>Of course, slowing ocean warming and preventing marine heatwaves from damaging ecosystems means slashing carbon emissions. But while we work on that, this knowledge could give us time to find strategies to reduce the undersea death toll – and the damage to tourism and fishing which rely on these ecosystems surviving. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/coral-reefs-how-climate-change-threatens-the-hidden-diversity-of-marine-ecosystems-211007">Coral reefs: How climate change threatens the hidden diversity of marine ecosystems</a>
</strong>
</em>
</p>
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<img src="https://counter.theconversation.com/content/211902/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Amandine Schaeffer receives funding from the Australian Research Council. </span></em></p><p class="fine-print"><em><span>Alex Sen Gupta receives funding from the Australian Research Council</span></em></p><p class="fine-print"><em><span>Moninya Roughan receives funding from the Australian Research Council, and Australia’s Integrated Marine Observing System (IMOS) – IMOS is enabled by the National Collaborative Research Infrastructure Strategy (NCRIS).</span></em></p>Marine heatwaves aren’t just on the surface. They can be at their most destructive when they sweep along the seafloor.Amandine Schaeffer, Senior lecturer, UNSW SydneyAlex Sen Gupta, Senior Lecturer, School of Biological, Earth and Environmental Sciences, UNSW SydneyMoninya Roughan, Professor in Oceanography, UNSW SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2105702023-07-28T16:24:22Z2023-07-28T16:24:22ZThe Atlantic is at risk of circulation collapse – it would mean even greater climate chaos across Europe<figure><img src="https://images.theconversation.com/files/539958/original/file-20230728-3774-595wvj.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C4265%2C2833&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">andrejs polivanovs / shutterstock</span></span></figcaption></figure><p>Amid news of lethal heatwaves across the Northern Hemisphere comes the daunting prospect of a climate disaster on an altogether grander scale. New findings published in <a href="https://www.nature.com/articles/s41467-023-39810-w">Nature Communications</a> suggest the Atlantic meridional overturning circulation, or Amoc, could collapse within the next few decades – maybe even within the next few years – driving European weather to even greater extremes.</p>
<p>The Amoc amounts to a system of currents in the Atlantic that bring warm water northwards where it then cools and sinks. It is a key reason why Europe’s climate has been stable for thousands of years, even if it’s hard to recognise this chaotic summer as part of that stability. </p>
<p>There is much uncertainty in these latest predictions and some scientists are <a href="https://www.bbc.co.uk/news/science-environment-66289494">less convinced</a> a collapse is imminent. Amoc is also only one part of the wider Gulf Stream system, much of which is driven by winds that will continue to blow even if the Amoc collapses. So part of the Gulf Stream will survive an Amoc collapse.</p>
<p>But I have studied the links between <a href="https://scholar.google.com/citations?user=xflmVSMAAAAJ&hl=en">Atlantic currents and the climate</a> for decades now, and know that an Amoc collapse would still lead to even greater climate chaos across Europe and beyond. At minimum, it is a risk worth being aware of.</p>
<h2>Amoc helps keep Europe warm and stable</h2>
<p>To appreciate how much Amoc influences the climate in the northeast Atlantic, consider how much warmer north Europeans feel compared to people at similar latitudes elsewhere. The following maps show how surface air temperatures depart from the average at each latitude and highlight patterns of warm and cool spots around the planet:</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/539777/original/file-20230727-25-mkqjxk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/539777/original/file-20230727-25-mkqjxk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/539777/original/file-20230727-25-mkqjxk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=720&fit=crop&dpr=1 600w, https://images.theconversation.com/files/539777/original/file-20230727-25-mkqjxk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=720&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/539777/original/file-20230727-25-mkqjxk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=720&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/539777/original/file-20230727-25-mkqjxk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=905&fit=crop&dpr=1 754w, https://images.theconversation.com/files/539777/original/file-20230727-25-mkqjxk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=905&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/539777/original/file-20230727-25-mkqjxk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=905&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Surface air temperature departure from 1948-2018 zonal average in January (top) and July (bottom).</span>
<span class="attribution"><a class="source" href="https://www.sciencedirect.com/book/9780128160596/ocean-currents">Marsh & van Sebille, 2021; Data: NCEP/NCAR</a>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Most striking in the northern winter (January) is a red spot centred to the west of Norway where temperatures are 20°C warmer than the latitude average, thanks to Amoc. The northeast Pacific – and therefore western Canada and Alaska – enjoys a more modest 10°C warming from a similar current, while prevailing westerly winds mean the northwest Atlantic and northwest Pacific are much colder, as are the adjacent land masses of eastern Canada and Siberia.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/539774/original/file-20230727-23-fw7bkx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Norwegian town beside sea, snowy mountain in background" src="https://images.theconversation.com/files/539774/original/file-20230727-23-fw7bkx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/539774/original/file-20230727-23-fw7bkx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/539774/original/file-20230727-23-fw7bkx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/539774/original/file-20230727-23-fw7bkx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/539774/original/file-20230727-23-fw7bkx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/539774/original/file-20230727-23-fw7bkx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/539774/original/file-20230727-23-fw7bkx.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">Lofoten, Norway, is beyond the Arctic Circle yet most days are above freezing even in midwinter. Relative to latitude, it’s one of the world’s warmest places.</span>
<span class="attribution"><span class="source">Dmitry Rukhlenko / shutterstock</span></span>
</figcaption>
</figure>
<p>The weather and climate of Europe, and northern Europe in particular, is highly variable from day to day, week to week and year to year, with competing air masses (warm and moist, cold and dry, and so on) gaining or losing influence, often guided by the high-altitude jet stream. Changes in weather and climate can be triggered by events located far away – and over the ocean.</p>
<h2>How ocean temperatures are linked to weather</h2>
<p>Over recent years Europe has witnessed some particularly unusual weather, in both winter and summer. At the same time, <a href="https://theconversation.com/weird-weather-blame-the-north-atlantic-53271">peculiar patterns of sea surface temperatures</a> have appeared across the North Atlantic. Across great swathes of the ocean from the tropics to the Arctic, temperatures have persisted 1°C-2°C above or below normal levels, for months or even years on end. These patterns appear to exert a strong influence on the atmosphere, even influencing the path and strength of the <a href="https://theconversation.com/britains-recent-wet-summers-can-be-blamed-on-the-atlantic-jet-stream-says-new-study-64337">jet stream</a>. </p>
<p>To an extent, we can attribute some of these sea surface temperature patterns to a changing Amoc, but it’s often not that straightforward. Nevertheless, the association of extreme seasons and weather with unusual sea temperatures might give us an idea of how a collapsed Amoc would unsettle the status quo. Here are three examples.</p>
<p>Northern Europe experienced successive severe winters in 2009/10 and 2010/11, subsequently attributed to a <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2011GL048978">brief slowdown of the Amoc</a>. At the same time heat had built up in the tropics, fuelling an <a href="https://www.nature.com/articles/s41467-019-08496-4">unusually active June-November hurricane season</a> in 2010.</p>
<p>In the mid 2010s a “cold blob” formed in the North Atlantic, reaching its most extreme in the summer of 2015 when it coincided with <a href="https://iopscience.iop.org/article/10.1088/1748-9326/11/7/074004/meta">heatwaves in central Europe</a> and was one of the only parts of the world cooler than its long-term average. </p>
<p>The cold blob looked suspiciously like the fingerprint of a weakened Amoc, but colleagues and I subsequently attributed this transient episode to <a href="https://www.annualreviews.org/doi/10.1146/annurev-marine-121916-063102">more local atmospheric influences</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/539944/original/file-20230728-24473-ud8ybo.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Shaded world map" src="https://images.theconversation.com/files/539944/original/file-20230728-24473-ud8ybo.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/539944/original/file-20230728-24473-ud8ybo.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/539944/original/file-20230728-24473-ud8ybo.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/539944/original/file-20230728-24473-ud8ybo.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/539944/original/file-20230728-24473-ud8ybo.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/539944/original/file-20230728-24473-ud8ybo.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/539944/original/file-20230728-24473-ud8ybo.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">Spot the blob: temperatures in 2015 – at the time, the warmest year on record – compared to long-term averages.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Cold_blob#/media/File:16-008-NASA-2015RecordWarmGlobalYearSince1880-20160120.png">NASA/NOAA</a></span>
</figcaption>
</figure>
<p>In 2017, the tropical Atlantic was again warmer than average and once again an unusually active hurricane season ensued, although the Amoc was not as clearly involved <a href="https://www.nature.com/articles/s41467-019-08496-4">as 2010</a>. Extensive warmth to the northeast in late 2017 may have sustained hurricane Ophelia, emerging around the Azores and making landfall in Ireland in October.</p>
<p>Based on just these few examples, we can expect that a more substantial reorganisation of North Atlantic surface temperatures will have profound consequences for the climate in Europe and beyond. </p>
<p>Larger ocean temperature extremes may alter the character of weather systems that are powered by heat and moisture from the sea – when and where temperatures rise beyond current extremes, Atlantic storms may grow <a href="https://theconversation.com/hurricane-ian-how-climate-change-is-making-north-atlantic-tropical-storms-worse-191547">more destructive</a>. More extreme ocean temperature patterns may exert further influences on tropical hurricane tracks and the jet stream, sending storms to <a href="https://theconversation.com/why-ex-hurricane-ophelia-took-a-wrong-turn-towards-ireland-and-britain-and-carried-all-that-dust-85851">ever more unlikely destinations</a>.</p>
<p>If the Amoc collapses we can expect larger extremes of heat, cold, drought and flooding, a range of “surprises” to exacerbate the current climate emergency. The potential climate impacts – on Europe in particular – should add urgency to our decision-making.</p>
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<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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</figure>
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<p class="fine-print"><em><span>Robert Marsh receives funding from the UK Natural Environment Research Council. </span></em></p>Expect more extremes and a range of ‘surprises’ to exacerbate the climate emergency.Robert Marsh, Professor of Oceanography and Climate, University of SouthamptonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2089222023-07-21T12:28:45Z2023-07-21T12:28:45ZRip currents are dangerous for swimmers but also ecologically important – here’s how scientists are working to understand these ‘rivers of the sea’<figure><img src="https://images.theconversation.com/files/537611/original/file-20230716-21935-qbqsh8.jpeg?ixlib=rb-1.1.0&rect=7%2C15%2C5168%2C3430&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The gap between breaking waves in North Carolina indicates a rip current flowing away from shore.</span> <span class="attribution"><a class="source" href="https://www.weather.gov/images/safety/photo/rip_nc18-1.JPG">National Weather Service</a></span></figcaption></figure><p>If you’ve ever waded into the ocean for a swim and suddenly realized that the shore is getting farther away, not closer, you may have encountered a rip current. Common at beaches worldwide, these powerful currents flow from the shore toward the sea at speeds up to several feet per second.</p>
<p>It’s important to know what rip currents are and how to <a href="https://oceantoday.noaa.gov/ripcurrentscience/">look for them</a>, because they are a <a href="https://www.washingtonpost.com/nation/2023/06/30/florida-beach-drownings-currents/">leading cause of drownings</a> in the surf zone near shore. According to one recent estimate, rip currents have accounted for <a href="https://floridapanhandle.com/blog/rip-current-statistics/">435 drownings in the U.S. since 2017</a>.</p>
<p>National Weather Service offices that serve coastal communities issue forecasts that predict where and when rip currents are likely to occur. Those forecasts draw on <a href="https://doi.org/10.1016/j.earscirev.2016.09.008">decades of research</a> into the physics of rip currents. Many scholars, including our research group, are finding innovative ways to discover more about rip currents – including their important roles in coastal marine ecosystems. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/RJ4hcaJ91TY?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Rip currents are narrow currents in the surf zone that move quickly away from shore.</span></figcaption>
</figure>
<h2>Not all rip currents are the same</h2>
<p>All rip currents have similar effects, but they can form in several ways. </p>
<p>One type of rip, known as a bathymetric or <a href="https://www.weather.gov/safety/ripcurrent-science">channel rip current</a>, forms when there are gaps between breaking waves. As waves break, they push water toward the beach and raise the level of the water slightly. </p>
<p>If waves break on a sandbar, but not in a deeper channel that cuts through the sandbar, the extra water that the waves have pushed toward the beach escapes back to the ocean through the channel. The flow of the escaping water acts like a conveyor belt, moving water, unsuspecting swimmers and small marine organisms offshore. </p>
<p>Another type, known as a transient or <a href="https://www.weather.gov/safety/ripcurrent-science">flash rip current</a>, forms when surf is choppy. The edges of breaking waves push on the water and make it spin, like a fast ice skater bumping into someone. </p>
<p>This creates whirls known as eddies, which can combine to form larger whirls, with currents that act like temporary conveyor belts. Flash rip currents are an active area of research. </p>
<h2>Swim, float, call for help</h2>
<p>Choosing beaches with lifeguards and paying attention to <a href="https://www.weather.gov/media/tae/RipCurrentFlags.pdf">beach flag warnings</a> are the best ways to avoid rip currents. However, if you get caught in one, here are some techniques for getting safely back to shore. </p>
<p>Think of a rip current as a swift river cutting through the surf away from the shore. Swimming against the current is going to tire you out and put you at risk of drowning. Instead, swim parallel to the beach – think of heading for the “river banks” – until you are out of the rip current’s pull. Once you’re no longer fighting it, you can swim back to shore. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/537619/original/file-20230716-138859-f52ks8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A barricaded pathway to a beach with a sign warning of drowning risk and barring swimming and surfing." src="https://images.theconversation.com/files/537619/original/file-20230716-138859-f52ks8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/537619/original/file-20230716-138859-f52ks8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/537619/original/file-20230716-138859-f52ks8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/537619/original/file-20230716-138859-f52ks8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/537619/original/file-20230716-138859-f52ks8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/537619/original/file-20230716-138859-f52ks8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/537619/original/file-20230716-138859-f52ks8.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">New York City closed public beaches in September 2019 after Hurricane Dorian caused strong rip currents along the Atlantic coast.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/sign-alerts-beach-goers-at-rockaway-beach-that-swimming-and-news-photo/1172788123">Spencer Platt/Getty Images)</a></span>
</figcaption>
</figure>
<p>Another strategy is to float until the rip current carries you offshore beyond the breaking waves. Rip currents slow down here, so you can swim away from the rip current and back to shore. </p>
<p>If you believe you’re in danger, try to stay calm. Wave your arms and call for help. If you see someone caught in a rip current, throw them a flotation device and alert a lifeguard. </p>
<h2>Forecasting rip currents</h2>
<p>The National Oceanic and Atmospheric Administration’s <a href="https://www.weather.gov/beach/">rip current hazard model</a> provides advance forecasts of the likelihood of encountering hazardous rip currents given wave conditions at specific beaches. NOAA works continually to make these hazard forecasts more accurate, including through an ongoing partnership with the <a href="https://www.usla.org/">U.S. Lifesaving Association</a>. This partnership works to compare modeled predictions with lifeguard reports of rip current hazards and to recalibrate the model for different regions and waves. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1678467698731409408"}"></div></p>
<p>At the University of Washington, we are <a href="https://doi.org/10.1175/WAF-D-17-0076.1">evaluating NOAA hazard forecasts</a> against the latest rip current science. This helps us assess predictions for different types of rip currents, such as unexpected flash rips. </p>
<p>To measure rip currents, we sometimes put on scuba gear and battle the waves to set up <a href="https://www.whoi.edu/oceanus/feature/the-riddle-of-rip-currents/">instruments in the surf</a>. But this work can be expensive, and it relies on knowing where rips will occur beforehand. That isn’t possible for flash rips, so we need different methods to analyze those.</p>
<p>We use supercomputers and <a href="https://engineering.oregonstate.edu/wave-lab">massive wave tanks</a> the size of an Olympic swimming pool, with paddles at one end that produce waves, to simulate flash rips. <a href="https://doi.org/10.1016/j.coastaleng.2023.104327">Wave tank laboratory experiments</a> and <a href="https://ui.adsabs.harvard.edu/abs/2022AGUFMOS42A..06N/abstract">computer simulations</a> allow us to control the types of waves we produce and make it easier to collect a lot of data. This work is improving our understanding of the relationship between wave conditions and flash rips, which can help improve hazard predictions. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/538371/original/file-20230719-27-t5e2i1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Waves in a large laboratory tank, stained with pink dye to track currents." src="https://images.theconversation.com/files/538371/original/file-20230719-27-t5e2i1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/538371/original/file-20230719-27-t5e2i1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=285&fit=crop&dpr=1 600w, https://images.theconversation.com/files/538371/original/file-20230719-27-t5e2i1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=285&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/538371/original/file-20230719-27-t5e2i1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=285&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/538371/original/file-20230719-27-t5e2i1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=358&fit=crop&dpr=1 754w, https://images.theconversation.com/files/538371/original/file-20230719-27-t5e2i1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=358&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/538371/original/file-20230719-27-t5e2i1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=358&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Pink dye exits the surf in a flash rip current (yellow arrow) during large-scale wave tank experiments.</span>
<span class="attribution"><span class="source">Christine Baker</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Expressways for marine life</h2>
<p>Rip currents aren’t just a safety issue. Scientists are beginning to better understand the crucial ecological role they play in <a href="https://doi.org/10.1146/annurev-marine-010816-060514">redistributing small marine organisms</a>, as well as plastic, pollutants, sediment and debris in coastal waters. </p>
<p>Many marine organisms, including oysters, barnacles, fish and coral, rely on <a href="https://tos.org/oceanography/assets/docs/20-3_pineda.pdf">ocean currents during their larval stage</a> to find suitable habitats. These organisms swim up or down or attach to floating or sinking material and are transported by <a href="https://doi.org/10.1146/annurev-marine-032122-115057">multiple ocean processes</a>. </p>
<p>Rip currents are a <a href="https://doi.org/10.1002/ecm.1265">key mechanism</a> for dispersing larvae to deeper waters or recirculating them in shallow waters. The rip current type and behavior may affect the movement of marine organisms. </p>
<p>Water temperature and salinity can change the behavior of rip currents – and send organisms on alternate routes – by modifying the water’s density. Our group has analyzed <a href="https://doi.org/10.1029/2020GL091675">imagery taken from low-flying planes</a> and found that warmer rip currents carry water farther offshore at the surface, whereas <a href="https://doi.org/10.1002/2017GL072611">cooler rip currents</a> spread beneath the surface in different patterns.</p>
<p>Our research group and other scientists are using computer simulations and numerical “larvae” to investigate how temperature, <a href="https://pinc.ucsd.edu/">salinity</a> and other factors may affect transport of marine organisms. With better understanding of these surf-zone conveyor belts, we aim to help keep swimmers safe and assess how rip currents affect aquatic ecosystems near the shore.</p><img src="https://counter.theconversation.com/content/208922/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Emma Shie Nuss receives funding from National Science Foundation and the Office of Naval Research. </span></em></p><p class="fine-print"><em><span>Audrey Casper receives funding from the National Science Foundation and the Office of Naval Research.</span></em></p><p class="fine-print"><em><span>Christine M. Baker receives funding from the National Science Foundation and a Department of Defense National Defense Science and Engineering Graduate Fellowship.</span></em></p><p class="fine-print"><em><span>Melissa Moulton receives funding from the National Science Foundation and the Office of Naval Research. </span></em></p><p class="fine-print"><em><span>Walter Torres receives funding from the National Science Foundation and the Office of Naval Research. </span></em></p>Rip currents are a leading cause of near-shore drownings, but there are effective ways to survive one. And these phenomena also play important ecological roles that are an emerging research area.Emma Shie Nuss, PhD Student in Civil and Environmental Engineering, University of WashingtonAudrey Casper, Data Analyst, NOAA Hazard Forecasting, University of WashingtonChristine M. Baker, Postdoctoral research scholar, North Carolina State UniversityMelissa Moulton, Research Scientist/Engineer, Applied Physics Laboratory, University of WashingtonWalter Torres, Postdoctoral Scholar, Applied Physics Laboratory, University of WashingtonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2083262023-06-23T12:29:43Z2023-06-23T12:29:43ZTitan submersible disaster underscores dangers of deep-sea exploration – an engineer explains why most ocean science is conducted with crewless submarines<figure><img src="https://images.theconversation.com/files/533576/original/file-20230622-19-hnt7xe.jpg?ixlib=rb-1.1.0&rect=6%2C6%2C4594%2C3055&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Researchers are increasingly using small, autonomous underwater robots to collect data in the world's oceans.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/noaaphotolib/27555260673/">NOAA Teacher at Sea Program,NOAA Ship PISCES</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p><em>Rescuers spotted debris from the tourist submarine Titan on the ocean floor near the wreck of the Titanic on June 22, 2023, <a href="https://www.nytimes.com/live/2023/06/22/us/titanic-missing-submarine/heres-the-latest-on-the-missing-submersible">indicating that the vessel suffered a catastrophic failure</a> and the five people aboard were killed.</em></p>
<p><em>Bringing people to the bottom of the deep ocean is inherently dangerous. At the same time, climate change means collecting data from the world’s oceans is more vital than ever. Purdue University mechanical engineer <a href="https://scholar.google.com/citations?user=z1BeTeYAAAAJ&hl=en">Nina Mahmoudian</a> explains how researchers reduce the risks and costs associated with deep-sea exploration: Send down subs, but keep people on the surface.</em></p>
<h2>Why is most underwater research conducted with remotely operated and autonomous underwater vehicles?</h2>
<p>When we talk about water studies, we’re talking about vast areas. And covering vast areas requires tools that can work for extended periods of time, sometimes months. Having people aboard underwater vehicles, especially for such long periods of time, is expensive and dangerous.</p>
<p>One of the tools researchers use is <a href="https://oceanexplorer.noaa.gov/facts/rov.html">remotely operated vehicles</a>, or ROVs. Basically, there is a cable between the vehicle and operator that allows the operator to command and move the vehicle, and the vehicle can relay data in real time. ROV technology has progressed a lot to be able to reach deep ocean – up to a depth of 6,000 meters (19,685 feet). It’s also better able to provide the mobility necessary for observing the sea bed and gathering data.</p>
<p><a href="https://oceanexplorer.noaa.gov/facts/auv.html">Autonomous underwater vehicles</a> provide another opportunity for underwater exploration. They are usually not tethered to a ship. They are typically programmed ahead of time to do a specific mission. And while they are underwater they usually don’t have constant communication. At some interval, they surface, relay the whole amount of data that they have gathered, change the battery or recharge and receive renewed instructions before again submerging and continuing their mission.</p>
<h2>What can remotely operated and autonomous underwater vehicles do that crewed submersibles can’t, and vice versa?</h2>
<p>Crewed submersibles will be exciting for the public and those involved and helpful for the increased capabilities humans bring in operating instruments and making decisions, similar to crewed space exploration. However, it will be much more expensive compared with uncrewed explorations because of the required size of the platforms and the need for life-support systems and safety systems. Crewed submersibles today <a href="https://www.nytimes.com/2015/09/15/science/piloted-deep-sea-research-is-bottoming-out.html">cost tens of thousands of dollars a day</a> to operate.</p>
<p>Use of unmanned systems will provide better opportunities for exploration at less cost and risk in operating over vast areas and in inhospitable locations. Using remotely operated and autonomous underwater vehicles gives operators the opportunity to perform tasks that are dangerous for humans, like observing under ice and detecting underwater mines.</p>
<figure>
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<figcaption><span class="caption">Remotely operated vehicles can operate under Antarctic ice and other dangerous places.</span></figcaption>
</figure>
<h2>How has the technology for deep ocean research evolved?</h2>
<p>The technology has advanced dramatically in recent years due to progress in sensors and computation. There has been great progress in <a href="https://doi.org/10.3390%2Fs21237849">miniaturization of acoustic sensors and sonars</a> for use underwater. Computers have also become more miniaturized, capable and power efficient. There has been a lot of work on battery technology and connectors that are watertight. <a href="https://www.additivemanufacturing.media/articles/autonomous-underwater-vehicle-with-3d-printed-hull-the-cool-parts-show-24">Additive manufacturing and 3D printing also help build hulls</a> and components that can withstand the high pressures at depth at much lower costs.</p>
<p>There has also been great progress toward increasing autonomy using more advanced algorithms, in addition to traditional methods for navigation, localization and detection. For example, machine learning algorithms can <a href="https://doi.org/10.1109/ICITR49409.2019.9407797">help a vehicle detect and classify objects</a>, whether stationary like a pipeline or mobile like schools of fish. </p>
<h2>What kinds of discoveries have been made using remotely operated and autonomous underwater vehicles?</h2>
<p>One example is underwater gliders. These are buoyancy-driven autonomous underwater vehicles. They can stay in water for months. They can collect data on pressure, temperature and salinity as they go up and down in water. All of these are very helpful for researchers to have an understanding of changes that are happening in oceans. </p>
<p>One of these platforms traveled across the North Atlantic Ocean <a href="https://www.marine.ie/site-area/news-events/news/silbo-autonomous-glider-finds-its-way-ireland-having-travelled-across">from the coast of Massachusetts to Ireland</a> for nearly a year in 2016 and 2017. The amount of data that was captured in that amount of time was unprecedented. To put it in perspective, a vehicle like that costs about $200,000. The operators were remote. Every eight hours the glider came to the surface, got connected to GPS and said, “Hey, I am here,” and the crew basically gave it the plan for the next leg of the mission. If a crewed ship was sent to gather that amount of data for that long it would cost in the millions. </p>
<p>In 2019, researchers used an autonomous underwater vehicle to <a href="https://www.wired.com/story/submarine-under-thwaites-glacier-gauge-rising-seas/">collect invaluable data</a> about the <a href="https://doi.org/10.1126/sciadv.abd7254">seabed beneath the Thwaites glacier</a> in Antarctica.</p>
<p>Energy companies are also using remotely operated and autonomous underwater vehicles for <a href="https://www.offshore-technology.com/news/deepocean-autonomous-drone-offshore/">inspecting and monitoring</a> offshore renewable energy and oil and gas infrastructure on the seabed.</p>
<h2>Where is the technology headed?</h2>
<p>Underwater systems are slow-moving platforms, and if researchers can deploy them in large numbers that would give them an advantage for covering large areas of ocean. A great deal of effort is being put into coordination and fleet-oriented autonomy of these platforms, as well as into advancing data gathering using onboard sensors such as cameras, sonars and dissolved oxygen sensors. Another aspect of advancing vehicle autonomy is real-time underwater decision-making and data analysis.</p>
<h2>What is the focus of your research on these submersibles?</h2>
<p>My team and I focus on developing navigational and mission-planning algorithms for persistent operations, meaning long-term missions with minimal human oversight. The goal is to respond to two of the main constraints in the deployment of autonomous systems. One is battery life. The other is unknown situations. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/_kS0_-qc_r0?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">The author’s research includes a project to allow autonomous underwater vehicles to recharge their batteries without human intervention.</span></figcaption>
</figure>
<p>For battery life, we work on at-sea recharging, both underwater and surface water. We are developing tools for autonomous deployment, recovery, recharging and data transfer for longer missions at sea. For unknown situations, we are working on recognizing and avoiding obstacles and adapting to different ocean currents – basically allowing a vehicle to navigate in rough conditions on its own. </p>
<p>To adapt to changing dynamics and component failures, we are working on methodologies to help the vehicle detect the change and compensate to be able to continue and finish the mission.</p>
<p>These efforts will enable long-term ocean studies including observing environmental conditions and mapping uncharted areas.</p><img src="https://counter.theconversation.com/content/208326/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Nina Mahmoudian receives funding from National Science Foundation and Office of Naval Research. </span></em></p>Dramatic improvements in computing, sensors and submersible engineering are making it possible for researchers to ramp up data collection from the oceans while also keeping people out of harm’s way.Nina Mahmoudian, Associate Professor of Mechanical Engineering, Purdue UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2024282023-04-12T12:10:59Z2023-04-12T12:10:59ZIn the turbulent Drake Passage, scientists find a rare window where carbon sinks quickly into the deep ocean<figure><img src="https://images.theconversation.com/files/520309/original/file-20230411-18-wrggfk.jpg?ixlib=rb-1.1.0&rect=274%2C263%2C3123%2C2296&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The Drake Passage, seen from Antarctica, is one of the most turbulent ocean regions on Earth.</span> <span class="attribution"><span class="source">Lilian Dove</span></span></figcaption></figure><p>Looking out across the Southern Ocean near Antarctica, I can see whales and seabirds diving in and out of the water as they feed on sea life in the lower levels of the food web. At the base of this food web are tiny phytoplankton – algae that grow at the ocean surface, taking up carbon from the atmosphere through photosynthesis, just as plants on land do.</p>
<p>Because of their small size, phytoplankton are at the mercy of the ocean’s swirling motions. They are also so abundant that the green swirls are often visible from space. </p>
<p>Typically, phytoplankton remain near the surface of the ocean. Some may slowly sink to depth because of gravity. But in the turbulent Drake Passage, a 520-mile-wide (850 km) bottleneck between Antarctica and South America, something unusual is happening, and it has an impact on how the ocean takes carbon dioxide – the main driver of global warming – out of the atmosphere.</p>
<figure class="align-center ">
<img alt="A satellite image shows green swirls off the South American coast." src="https://images.theconversation.com/files/520127/original/file-20230411-24-4z7ae3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/520127/original/file-20230411-24-4z7ae3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=511&fit=crop&dpr=1 600w, https://images.theconversation.com/files/520127/original/file-20230411-24-4z7ae3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=511&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/520127/original/file-20230411-24-4z7ae3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=511&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/520127/original/file-20230411-24-4z7ae3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=643&fit=crop&dpr=1 754w, https://images.theconversation.com/files/520127/original/file-20230411-24-4z7ae3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=643&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/520127/original/file-20230411-24-4z7ae3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=643&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A satellite image captures a green phytoplankton bloom off the coast of Argentina. The Drake Passage is at the country’s southern end.</span>
<span class="attribution"><a class="source" href="https://oceancolor.gsfc.nasa.gov/gallery/612/">NASA Aqua/MODIS</a></span>
</figcaption>
</figure>
<h2>The Drake Passage</h2>
<p>The Drake Passage is notorious for its violent seas, with waves that can top 40 feet (12 meters) and <a href="https://doi.org/10.1038/s43247-022-00644-x">powerful converging currents</a>, some flowing as fast as <a href="https://doi.org/10.1002/2016GL070319">150 million cubic meters per second</a>. Cold water from the Southern Ocean and warmer water from the north collide here, spinning off <a href="https://doi.org/10.1175/JPO-D-18-0150.1">powerful and energetic eddies</a>.</p>
<p>New scientific research I am involved in <a href="https://scholar.google.com/citations?user=AlCIFFYAAAAJ&hl=en">as an oceanographer</a> now shows how the Drake Passage and a few other specific areas of the Southern Ocean play an outsize role in how the oceans lock up carbon from the atmosphere.</p>
<figure class="align-center ">
<img alt="A map shows the underwater ridges and continental shelves." src="https://images.theconversation.com/files/520123/original/file-20230411-22-3zv2hv.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/520123/original/file-20230411-22-3zv2hv.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=559&fit=crop&dpr=1 600w, https://images.theconversation.com/files/520123/original/file-20230411-22-3zv2hv.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=559&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/520123/original/file-20230411-22-3zv2hv.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=559&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/520123/original/file-20230411-22-3zv2hv.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=702&fit=crop&dpr=1 754w, https://images.theconversation.com/files/520123/original/file-20230411-22-3zv2hv.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=702&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/520123/original/file-20230411-22-3zv2hv.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=702&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A topographic map of the Drake Passage between South America and Antarctica.</span>
<span class="attribution"><a class="source" href="https://www.ncei.noaa.gov/products/etopo-global-relief-model.">NCEI/NOAA</a></span>
</figcaption>
</figure>
<p>That process is crucial for our understanding of the climate. The global ocean is a massive reservoir of carbon, holding over <a href="https://science.nasa.gov/earth-science/oceanography/ocean-earth-system/ocean-carbon-cycle">50 times as much carbon</a> as the atmosphere. However, it is only when water carrying carbon <a href="https://doi.org/10.1029/2020GB006790">gets to the deep ocean</a> that carbon can be stored for long periods – up to centuries or millennia.</p>
<p>Photosynthetic phytoplankton are at the heart of that exchange. And in the Drake Passage, my colleagues and I have found that undersea mountains are stirring things up.</p>
<h2>The role of ocean layers</h2>
<p>The ocean can be visualized as having layers. With constant surface waves and winds, the upper layer is always stirring around, mixing waters. It’s like mixing milk into your morning coffee. This stirring <a href="https://doi.org/10.1038/s41467-020-18203-3">mixes in solar heat and gases</a>, such as carbon dioxide, taken up from the atmosphere.</p>
<p>Water density generally increases as the waters get deeper and colder and saltier. That forms density layers that are typically flat. Since water prefers to keep its density constant, it mostly moves horizontally and doesn’t easily move between the surface and deep ocean.</p>
<figure class="align-center ">
<img alt="A graphic shows the typical ocean density layers, with phytoplankton in the upper layers." src="https://images.theconversation.com/files/520160/original/file-20230411-24-1kv12p.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/520160/original/file-20230411-24-1kv12p.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=485&fit=crop&dpr=1 600w, https://images.theconversation.com/files/520160/original/file-20230411-24-1kv12p.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=485&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/520160/original/file-20230411-24-1kv12p.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=485&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/520160/original/file-20230411-24-1kv12p.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=610&fit=crop&dpr=1 754w, https://images.theconversation.com/files/520160/original/file-20230411-24-1kv12p.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=610&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/520160/original/file-20230411-24-1kv12p.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=610&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">In most of the ocean, water stays within a density layer and doesn’t mix with colder, saltier water.</span>
<span class="attribution"><span class="source">Lilian Dove</span></span>
</figcaption>
</figure>
<p>Yet despite this physical barrier, water testing shows that carbon dioxide produced by human activities is making its way into the deep ocean. One way is through chemistry: Carbon dioxide dissolves in water, creating carbonic acid. Living creatures in the ocean are another.</p>
<h2>A view into the Drake Passage</h2>
<p>Oceanographers have long pointed to the north Atlantic Ocean and the Southern Ocean as places <a href="https://www.jstor.org/stable/24862019">where surface waters are moved to depth</a>, taking large volumes of carbon with them. However, recent work has shown that this process may actually be dominated by only a few areas – <a href="https://doi.org/10.1029/2022GL102550">including the Drake Passage</a>.</p>
<p>Despite its being one of the most famous stretches of the ocean, scientists have only recently been able to observe this window in action.</p>
<p>The main flow of the Drake Passage is created by the effect of strong westerly winds across the Southern Ocean. Scientists have found that the westerly winds create a slope in the water density, with dense waters shallower closer to Antarctica, where colder melt water caps the surface, but sloping deeper into the ocean farther north toward South America.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/520164/original/file-20230411-26-mi0289.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Side-by-side graphics show (1) the typical ocean density layers and (2) the sloped density layers in the Drake Passage." src="https://images.theconversation.com/files/520164/original/file-20230411-26-mi0289.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/520164/original/file-20230411-26-mi0289.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=390&fit=crop&dpr=1 600w, https://images.theconversation.com/files/520164/original/file-20230411-26-mi0289.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=390&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/520164/original/file-20230411-26-mi0289.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=390&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/520164/original/file-20230411-26-mi0289.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=490&fit=crop&dpr=1 754w, https://images.theconversation.com/files/520164/original/file-20230411-26-mi0289.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=490&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/520164/original/file-20230411-26-mi0289.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=490&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Unlike in most of the ocean, density layers in the Drake Passage slope downward, allowing phytoplankton to mix downward as well as sideways.</span>
<span class="attribution"><span class="source">Lilian Dove</span></span>
</figcaption>
</figure>
<p>With advances in <a href="https://doi.org/10.1029/2022GL102550">autonomous underwater robots</a> and computer modeling, we have been able to show how the flow of the Southern Ocean interacts with an underwater mountain in the Drake Passage. This underwater interaction <a href="https://doi.org/10.1029/2021GL097574">mixes up the ocean</a>, enhancing that coffeelike stirring process.</p>
<p>The stirring along the sloped density levels provides a pathway for water from the upper layer of the ocean to move into the depths. And phytoplankton at the surface ocean are carried along with this stirring, moving to depth much faster than they would by gravitational sinking alone.</p>
<p>In a less energetic region, these phytoplankton would die and respire their carbon back to the atmosphere or slowly sink. However, at the Drake Passage, phytoplankton can be swept to depth before this happens, meaning the carbon they’ve taken up from the atmosphere is sequestered in the deep ocean. Carbon dissolved and stored in the deep ocean may also vent out in these locations. </p>
<figure class="align-center ">
<img alt="Three people bundled up in winter gear work on a large seagoing drone." src="https://images.theconversation.com/files/520122/original/file-20230411-18-thnam3.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/520122/original/file-20230411-18-thnam3.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/520122/original/file-20230411-18-thnam3.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/520122/original/file-20230411-18-thnam3.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/520122/original/file-20230411-18-thnam3.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/520122/original/file-20230411-18-thnam3.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/520122/original/file-20230411-18-thnam3.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">Author Lilian Dove, at right, works with oceanographer Isa Rosso and marine technician Richard Thompson to prepare an oceangoing autonomous vehicle to take measurements in the Southern Ocean.</span>
<span class="attribution"><span class="source">Linnah Neidel</span></span>
</figcaption>
</figure>
<p>Scientists have estimated that the deepest ocean waters directly interact with the atmosphere through only about <a href="https://doi.org/10.1038/308621a0">5% of the ocean’s surface area</a>. This is one of those special places.</p>
<p>Investigating the Drake Passage and other oceanographic windows allows science to home in on better understanding climate change and the workings of our blue planet.</p><img src="https://counter.theconversation.com/content/202428/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Lilian Dove receives funding from the National Science Foundation and Resnick Sustainability Institute.</span></em></p>Working with underwater robots, scientists show how deep sea mountains and fast currents between Antarctica and South America play a crucial role in stabilizing the climate.Lilian (Lily) Dove, Ph.D. Candidate in Oceanography, California Institute of TechnologyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1932732023-01-17T13:32:55Z2023-01-17T13:32:55ZDeep seabed mining plans pit renewable energy demand against ocean life in a largely unexplored frontier<p>As companies race to expand renewable energy and the batteries to store it, finding sufficient amounts of rare earth metals to build the technology is no easy feat. That’s leading mining companies to take a closer look at a largely unexplored frontier – the deep ocean seabed. </p>
<p>A wealth of these metals can be found in manganese nodules that look like cobblestones scattered across wide areas of deep ocean seabed. But the fragile ecosystems deep in the oceans are little understood, and the mining codes to sustainably mine these areas are in their infancy.</p>
<p>A fierce debate is now playing out as a Canadian company makes plans to launch the first commercial deep sea mining operation in the Pacific Ocean. </p>
<p>The Metals Company completed an <a href="https://www.juniorminingnetwork.com/junior-miner-news/press-releases/3013-nasdaq/tmc/131137-nori-and-allseas-lift-over-3-000-tonnes-of-polymetallic-nodules-to-surface-from-planet-s-largest-deposit-of-battery-metals-as-leading-scientists-and-marine-experts-continue-gathering-environmental-data.html">exploratory project</a> in the Pacific Ocean <a href="https://www.nytimes.com/2022/11/03/world/deep-sea-mining.html">in fall 2022</a>. Under a treaty governing the deep sea floor, the international agency overseeing these areas could be forced to approve provisional mining there as soon as spring 2023, but several countries and companies are urging a delay until more research can be done. <a href="https://www.theguardian.com/environment/2022/jul/01/stop-deep-sea-mining-says-macron-in-call-for-new-laws-to-protect-ecosystems">France</a> and <a href="https://www.nzherald.co.nz/nz/government-backs-seabed-mining-ban-in-international-waters-until-strong-environmental-rules-in-place/F7RANMLZIFA3FLWC4JLAEN5TXU/">New Zealand</a> have called for a ban on deep sea mining. </p>
<p>As scholars who have long focused on the <a href="https://www.cambridge.org/core/journals/journal-of-benefit-cost-analysis/article/abs/addressing-fundamental-uncertainty-in-benefitcost-analysis-the-case-of-deep-seabed-mining/75801881799BD7EB2D3CF7B33C4DDAC6">economic</a>, <a href="https://global.oup.com/academic/product/the-poseidon-project-9780190265649?cc=us&lang=en&">political</a> and <a href="https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3790524">legal</a> <a href="https://www.cambridge.org/core/books/abs/governing-new-frontiers-in-the-information-age/conclusion/3FD2DF4571D325624C012301C94EDF7F">challenges</a> posed by deep seabed mining, we have each studied and written on this economic frontier with concern for the regulatory and ecological challenges it poses.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/501179/original/file-20221214-15837-osjj0p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A view looking across a sea floor with nodules looking like cobblestones on a street." src="https://images.theconversation.com/files/501179/original/file-20221214-15837-osjj0p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/501179/original/file-20221214-15837-osjj0p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/501179/original/file-20221214-15837-osjj0p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/501179/original/file-20221214-15837-osjj0p.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/501179/original/file-20221214-15837-osjj0p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/501179/original/file-20221214-15837-osjj0p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/501179/original/file-20221214-15837-osjj0p.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">Manganese nodules on the seafloor in the Clarion-Clipperton Zone, between Hawaii and Mexico, captured on camera by a remote vehicle in 2015.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:2015-04-14_18-20-14_Sonne_SO239_157ROV11_Logo_original(1).jpg">ROV KIEL 6000, GEOMAR</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>What’s down there, and why should we care?</h2>
<p>A curious journey began in the summer of 1974. Sailing from Long Beach, California, a revolutionary ship funded by eccentric billionaire Howard Hughes set course for the Pacific to open a new frontier — <a href="http://www.bbc.co.uk/news/resources/idt-sh/deep_sea_mining">deep seabed mining</a>. </p>
<p>Widespread media coverage of the expedition helped to focus the attention of businesses and policymakers on the promise of deep seabed mining, which is notable given that the expedition was actually an <a href="https://www.cia.gov/readingroom/document/0005301269">elaborate cover for a CIA operation</a>.</p>
<p>The real target was a Soviet ballistic missile submarine that had sunk in 1968 with all hands and what was believed to be a treasure trove of Soviet state secrets and tech onboard.</p>
<p>The <a href="https://www.cia.gov/readingroom/docs/DOC_0005301269.pdf">expedition, called Project Azorian by the CIA</a>, <a href="https://www.smithsonianmag.com/history/during-cold-war-ci-secretly-plucked-soviet-submarine-ocean-floor-using-giant-claw-180972154/">recovered at least part</a> of the submarine – and it also brought up several manganese nodules from the seafloor.</p>
<p>Manganese nodules are <a href="https://www.researchgate.net/publication/264763450_The_Geology_of_Manganese_Nodules">roughly the size of potatoes</a> and can be found across vast areas of seafloor in parts of the Pacific and Indian oceans and <a href="https://oceanexplorer.noaa.gov/okeanos/explorations/ex2104/features/nodule/welcome.html">deep abyssal plains in the Atlantic</a>. They are valuable because they are exceptionally rich in 37 metals, including nickel, cobalt and copper, which are essential for most large batteries and several renewable energy technologies.</p>
<p>These nodules <a href="https://oceanexplorer.noaa.gov/okeanos/explorations/ex2104/features/nodule/welcome.html">form over millennia</a> as metals nucleate around shells or broken nodules. The Clarion-Clipperton Zone, between Mexico and Hawaii in the Pacific Ocean, where the mining test took place, has been estimated to have over 21 billion metric tons of nodules that could provide <a href="https://www.researchgate.net/publication/264763450_The_Geology_of_Manganese_Nodules">twice as much nickel and three times more cobalt</a> than all the reserves on land.</p>
<p>Mining in the Clarion-Clipperton Zone could be some <a href="https://www.cambridge.org/core/books/abs/governing-new-frontiers-in-the-information-age/conclusion/3FD2DF4571D325624C012301C94EDF7F">10 times richer</a> than <a href="https://www.bbc.co.uk/news/resources/idt-sh/deep_sea_mining">comparable</a> mineral deposits on land. All told, estimates place the value of this new industry at some US$30 billion annually by 2030. It could be instrumental in feeding the surging global demand for cobalt that lies at the <a href="https://www.energy.gov/eere/vehicles/articles/reducing-reliance-cobalt-lithium-ion-batteries">heart of lithium-ion batteries</a>.</p>
<p>Yet, as several scientists have noted, we still know more about the surface of the moon than what lies at the bottom of the deep seabed.</p>
<h2>Deep seabed ecology</h2>
<p>Less than 10% of the deep seabed has been <a href="https://oceanservice.noaa.gov/facts/exploration.html">mapped</a> thoroughly enough to understand even the basic features of the structure and contents of the ocean floor, let alone the life and ecosystems therein.</p>
<p>Even the <a href="https://www.pewtrusts.org/en/research-and-analysis/fact-sheets/2017/12/the-clarion-clipperton-zone">most thoroughly studied region</a>, the Clarion-Clipperton Zone, is still best characterized by the persistent novelty of what is found there.</p>
<p>Between <a href="https://doi.org/10.1016/j.marpol.2022.105006">70% and 90% of living things</a> collected in the Clarion-Clipperton Zone have never been seen before, leaving scientists to speculate about what percentage of all living species in the region has never been seen or collected. Exploratory expeditions regularly return with images or samples of creatures that would richly animate science fiction stories, like a <a href="https://www.smithsonianmag.com/smart-news/nearly-six-foot-glowing-shark-discovered-deep-sea-new-zealand-180977163/">6-foot-long bioluminescent shark</a>.</p>
<p>Also <a href="https://doi.org/10.1016/j.marpol.2022.105006">unknown is the impact that deep sea mining</a> would have on these creatures.</p>
<p>An experiment in 2021 in water about 3 miles (5 kilometers) deep off Mexico found that seabed mining equipment <a href="https://doi.org/10.1126/sciadv.abn1219">created sediment plumes</a> of up to about 6.5 feet (2 meters) high. But <a href="https://scripps.ucsd.edu/news/study-gives-new-insights-nature-deep-sea-sediment-plumes">the project authors stressed that they didn’t study</a> the ecological impact. A similar earlier experiment was conducted off Peru in 1989. When scientists returned to that site in 2015, they found <a href="https://doi.org/10.1038/s41598-019-44492-w">some species still hadn’t fully recovered</a>.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/SR6o2WqX6uo?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Video from MIT shows the sediment plume created by a nodule-collecting machine during an experiment.</span></figcaption>
</figure>
<p><a href="https://www.pewtrusts.org/en/research-and-analysis/articles/2022/12/08/momentum-builds-to-halt-the-commencement-of-seabed-mining-in-international-waters">Environmentalists have questioned</a> whether seafloor creatures could be smothered by sediment plumes and whether the sediment in the water column could effect island communities that rely on healthy oceanic ecosystems. The Metals Company has argued that its <a href="https://www.mining.com/the-metals-company-reigniting-race-to-mine-the-ocean-floor/">impact is less</a> than terrestrial mining.</p>
<p>Given humanity’s <a href="https://doi.org/10.1016/j.marpol.2022.105006">lack of knowledge</a> of the ocean, it is not currently possible to set environmental baselines for oceanic health that could be used to weigh the economic benefits against the environmental harms of seabed mining.</p>
<h2>Scarcity and the economic case for mining</h2>
<p>The economic case for deep seabed mining reflects both possibility and uncertainty.</p>
<p>On the positive side, it could displace some highly destructive terrestrial mining and augment the global supply of minerals used in clean energy sources such as wind turbines, photovoltaic cells and electric vehicles. </p>
<p>Terrestrial mining imposes significant environmental damage and costs to human health of both the miners themselves and the surrounding communities. Additionally, mines are sometimes located in politically unstable regions. The <a href="https://www.nytimes.com/2021/11/20/world/china-congo-cobalt.html">Democratic Republic of Congo produces 60%</a> of the global supply of cobalt, for example, and China owns or finances 80% of industrial mines in that country. China also accounts for <a href="https://www.brinknews.com/china-is-moving-rapidly-up-the-rare-earth-value-chain/">60% of the global supply</a> of rare earth element production and much of its processing. Having one nation able to exert such control over a critical resource has <a href="https://www.nytimes.com/2021/11/21/world/us-china-energy.html">raised concerns</a>.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/iydMJToa2iU?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">The Metals Company shared video of its first collection mission.</span></figcaption>
</figure>
<p>Deep seabed mining comes with significant uncertainties, however, particularly given the technology’s relatively early state.</p>
<p>First are the risks associated with commercializing a new technology. Until deep sea mining technology is demonstrated, discoveries cannot be listed as “reserves” in firms’ asset valuations. Without that value defined, it can be difficult to line up the significant financing needed to build mining infrastructure, which lessens the first-mover advantage and incentivizes firms to wait for someone else to take the lead. </p>
<p>Commodity prices are also difficult to predict. Technology innovation can reduce or even eliminate the projected demand for a mineral. New mineral deposits on land can also boost supply: Sweden announced in January 2023 that it had <a href="https://www.reuters.com/markets/commodities/swedens-lkab-finds-europes-biggest-deposit-rare-earth-metals-2023-01-12/">just discovered</a> the largest deposit of rare earth oxides in Europe.</p>
<p>In all, embarking on deep seabed mining involves sinking <a href="https://investors.metals.co/news-releases/news-release-details/metals-company-provides-q3-corporate-update">significant costs</a> into new technology for uncertain returns, while posing risks to a natural environment that is likely to rise in value.</p>
<h2>Who gets to decide the future of seafloor mining?</h2>
<p>The <a href="https://www.imo.org/en/OurWork/Legal/Pages/UnitedNationsConventionOnTheLawOfTheSea.aspx">United Nations Convention on the Law of the Sea</a>, which came into force in the early 1990s, provides the basic rules for ocean resources.</p>
<p>It allows countries to control economic activities, including any mining, within 200 miles of their coastlines, accounting for approximately 35% of the ocean. Beyond national waters, countries around the world established the <a href="https://www.isa.org.jm/">International Seabed Authority</a>, or ISA, based in Jamaica, to regulate deep seabed mining.</p>
<p>Critically, the ISA framework calls for some of the profits derived from commercial mining to be shared with the international community. In this way, even countries that did not have the resources to mine the deep seabed could share in its benefits. This part of the ISA’s mandate was controversial, and it was one reason that the <a href="https://www.cfr.org/blog/international-treaties-united-states-refuses-play-ball">United States did not join</a> the Convention on the Law of the Sea.</p>
<p>With little public attention, the ISA worked slowly for several decades to develop regulations for exploration of undersea minerals, and those rules still aren’t completed. More than a dozen companies and countries have received <a href="https://www.isa.org.jm/exploration-contracts">exploration contracts</a>, including The Metals Company’s work under the sponsorship of the island nation of Nauru.</p>
<p>ISA’s work has started to draw criticism as companies have sought to initiate commercial mining. A <a href="https://www.nytimes.com/2022/08/29/world/deep-sea-mining.html">recent New York Times investigation</a> of <a href="https://www.documentcloud.org/documents/22266044-seabed-mining-selected-documents-2022">internal ISA documents</a> suggested the agency’s leadership has downplayed environmental concerns and shared confidential information with some of the companies that would be involved in seabed mining. The ISA <a href="https://isa.org.jm/iwg-inspection-compliance-and-enforcement-part-3">hasn’t finalized environmental rules for mining</a>.</p>
<p>Much of the coverage of deep seabed mining has been framed to highlight the climate benefits. But this overlooks the dangers this activity could pose for the Earth’s largest pristine ecology – the deep sea. We believe it would be wise to better understand this existing, fragile ecosystem better before rushing to mine it.</p><img src="https://counter.theconversation.com/content/193273/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Scott Shackelford is a principal investigator on grants from the Hewlett Foundation, Carnegie Corporation of New York, National Science Foundation, and the Microsoft Corporation supporting both the Ostrom Workshop Program on Cybersecurity and Internet Governance and the Indiana University Cybersecurity Clinic.</span></em></p><p class="fine-print"><em><span>David Bosco has received funding from the Pew Charitable Trusts for research on the work of the International Seabed Authority.</span></em></p><p class="fine-print"><em><span>Kerry Krutilla was the principal investigator for a World-Bank sponsored project on deep seabed mining. </span></em></p><p class="fine-print"><em><span>Christiana Ochoa 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>Mining nodules from the deep ocean seabed could provide the metals crucial for today’s EV batteries and renewable energy technology, but little is known about the harm it could cause.Scott Shackelford, Professor of Business Law and Ethics, Indiana UniversityChristiana Ochoa, Professor of Law, Indiana UniversityDavid Bosco, Associate Professor of International Studies, Indiana UniversityKerry Krutilla, Professor of Environmental and Energy Policy, Indiana UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1950152022-11-21T11:36:24Z2022-11-21T11:36:24ZGroundbreaking studies of Earth’s churning oceans recognised at Australia’s most prestigious science prizes this year<figure><img src="https://images.theconversation.com/files/496396/original/file-20221121-14-7m0lqx.jpg?ixlib=rb-1.1.0&rect=609%2C0%2C6173%2C4311&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://svs.gsfc.nasa.gov/cgi-bin/details.cgi?aid=3827">Greg Shirah/NASA Scientific Visualisation Studio</a></span></figcaption></figure><p>This year, Australia’s prestigious Prime Minister’s Prize for Science has been awarded to a physical oceanographer whose work has had a “transformative impact” on our understanding of Earth’s oceans.</p>
<p>Professor Trevor McDougall AC from the University of New South Wales has made major contributions to unveiling the fundamental physics of the ocean.</p>
<p>During his illustrious career, McDougall has discovered previously unknown ocean mixing processes – the turbulent ways seawater churns and <a href="https://www.uib.no/en/rg/fysos/53334/ocean-mixing">irreversibly changes</a> under various conditions.</p>
<p>His discoveries have improved climate models, allowing us to better predict our planet’s fast-changing future.</p>
<p>“The ocean is notoriously difficult to observe; we know more about the surface of the Moon than we do about the seafloor,” McDougall said.</p>
<p>“We study the ocean because it transports a lot of heat from the equatorial regions towards the poles and also because it acts as the thermal flywheel of the climate system.” </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/496389/original/file-20221121-12-1clq6g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A smiling older gentleman looking at the camera with the sea in the background" src="https://images.theconversation.com/files/496389/original/file-20221121-12-1clq6g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/496389/original/file-20221121-12-1clq6g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=900&fit=crop&dpr=1 600w, https://images.theconversation.com/files/496389/original/file-20221121-12-1clq6g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=900&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/496389/original/file-20221121-12-1clq6g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=900&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/496389/original/file-20221121-12-1clq6g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1131&fit=crop&dpr=1 754w, https://images.theconversation.com/files/496389/original/file-20221121-12-1clq6g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1131&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/496389/original/file-20221121-12-1clq6g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1131&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Trevor McDougall is a world-leading researcher in ocean thermodynamics.</span>
<span class="attribution"><span class="source">Supplied</span></span>
</figcaption>
</figure>
<p>A world-leading authority on ocean mixing, McDougall was recognised for his many contributions, including a redefinition of the thermodynamic description of seawater. The latter <a href="https://csiropedia.csiro.au/science-adopts-a-new-definition-of-seawater/">was accepted by</a> the Intergovernmental Oceanographic Commission in 2009 as a new international standard. </p>
<p>“To receive the Prime Minister’s Prize for Science is an incredible honour, and it’s also an honour for the early career researchers that I’ve been working with for the past ten years,” said McDougall.</p>
<p>“They’ve been integral to some of the results that have been recognised in this prize.” </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-ocean-is-becoming-more-stable-heres-why-that-might-not-be-a-good-thing-157911">The ocean is becoming more stable – here's why that might not be a good thing</a>
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<hr>
<h2>Predicting sea level rise</h2>
<p>Earth’s oceans and their role in climate change are also the focus of another prize recipient this year – physical oceanographer and ocean modeller Dr Adele Morrison from the Australian National University (ANU). </p>
<p>She won the Malcolm McIntosh Prize for Physical Scientist of the Year for her innovative methods of modelling ocean circulation around Antarctica.</p>
<p>Morrison’s research has greatly reduced uncertainty in predicting future sea level rise from Antarctic ice sheet melt, driven by warm ocean currents in the Southern Ocean.</p>
<figure class="align-center ">
<img alt="A smiling woman with curly hair looking at the camera with greenery in the background" src="https://images.theconversation.com/files/496391/original/file-20221121-18-9zfgta.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/496391/original/file-20221121-18-9zfgta.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/496391/original/file-20221121-18-9zfgta.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/496391/original/file-20221121-18-9zfgta.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/496391/original/file-20221121-18-9zfgta.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/496391/original/file-20221121-18-9zfgta.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/496391/original/file-20221121-18-9zfgta.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">Adele Morrison’s work has revealed the ongoing impact of warm ocean currents on Antarctic ice melt.</span>
<span class="attribution"><span class="source">Supplied</span></span>
</figcaption>
</figure>
<p>Such work is particularly pertinent to Australia, with 85% of Australians living in places that could soon be affected by rising sea levels.</p>
<p>Morrison hopes to “inspire the next generation of scientists to unravel new discoveries and technologies that limit the impacts of climate change and our transition to a zero-emissions world”.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/satellites-reveal-ocean-currents-are-getting-stronger-with-potentially-significant-implications-for-climate-change-159461">Satellites reveal ocean currents are getting stronger, with potentially significant implications for climate change</a>
</strong>
</em>
</p>
<hr>
<h2>Molecular diagnostics and solar cell improvements also recognised</h2>
<p>Several other researchers and inventors received accolades at the ceremony held on November 21 at Parliament House in Canberra.</p>
<ul>
<li><p>Adjunct Professor Alison Todd and Dr Elisa Mokany, co-founders of the molecular diagnostics company SpeeDx, received the Prize for Innovation. Their highly advanced diagnostic tests have improved diagnosis and treatments for several infectious diseases and cancers.</p></li>
<li><p>The other Prize for Innovation went to Dr Nick Cutmore, Dr James Tickner and Mr Dirk Treasure of the company Chrysos. They have successfully commercialised an X-ray technology that measures the presence of gold and minerals in ore samples.</p></li>
<li><p>Professor Si Ming Man from ANU was awarded the Frank Fenner Prize for Life Scientist of the Year for his work on inflammation and new therapies for inflammatory diseases.</p></li>
<li><p>The Prize for New Innovators went to University of Melbourne’s Dr Pip Karoly, whose unique seizure forecasting technology is improving the lives of millions of people with epilepsy.</p></li>
<li><p>UNSW Associate Professor Brett Hallam was also awarded the Prize for New Innovators, whose discoveries and patented tech have improved solar cell performance by a whopping 10%.</p></li>
</ul>
<h2>Inspiring our youngest future scientists</h2>
<p>Each year, the prizes also include recognition for outstanding achievements in science teaching.</p>
<p>Mr George Pantazis from Marble Bar Primary School in Western Australia was awarded the Prize for Excellence in Science Teaching in Primary Schools for his work integrating First Nations cultural knowledge, including the critically endangered Nyamal language, in the school’s science, technology, engineering, and mathematics (STEM) program.</p>
<p>This “wouldn’t be possible without the support of our teachers and the community, in particular the Nyamal people and their Elders”, said Pantazis.</p>
<p>“This prize is the highlight of my career. I owe it all to the students. Without them, I have nothing.”</p>
<p>The Prize for Excellence in Science Teaching in Secondary Schools went to Ms Veena Nair from Viewbank College, Victoria. She has collaborated with countless academics and industry leaders to not only show students the practical application of STEAM (science, technology, engineering, arts and mathematics) subjects, but also find pathways for them in STEAM careers.</p>
<p>“As a first-generation migrant, I’m deeply thankful to my birth country India, where I got my foundation skills – and to my adopted country Australia, where I was given the wings to fly,” said Nair.</p>
<p>For 23 years now, the Prime Minister’s Science Prizes have been awarded for outstanding achievements in scientific research, research-based innovation and excellence in science teaching. The recipients share a prize pool of $750,000.</p>
<p>This is the first year since 2019 the prizes were held at the Parliament House again, with the 2020 and 2021 events having taken place virtually.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/explainer-whats-the-difference-between-stem-and-steam-95713">Explainer: what's the difference between STEM and STEAM?</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/195015/count.gif" alt="The Conversation" width="1" height="1" />
The 2022 Prime Minister’s Science Prizes have been awarded for outstanding achievements in scientific research, innovation and teaching.Signe Dean, Science + Technology Editor, The ConversationLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1646902021-07-23T12:15:09Z2021-07-23T12:15:09ZSurfing makes its Olympic debut – and the waves should be world-class thanks to wind, sand and a typhoon or two<figure><img src="https://images.theconversation.com/files/412283/original/file-20210720-21-1gy3edx.jpg?ixlib=rb-1.1.0&rect=523%2C0%2C2726%2C2418&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Hawaiian surfer John John Florence, seen here competing in Portugal, is one of the favorites to win surfing's first Olympic gold. </span> <span class="attribution"><a class="source" href="https://newsroom.ap.org/detail/PortugalSurf/28db9b5fff044e9186c7db8caa8d855f/photo?Query=surfing%20john%20florence&mediaType=photo&sortBy=&dateRange=Anytime&totalCount=18&currentItemNo=0">AP Photo/Francisco Seco</a></span></figcaption></figure><p>For the first time, <a href="https://olympics.com/tokyo-2020/en/sports/surfing/">surfing is on the Olympic stage</a>. </p>
<p>The surfing event will last for three days and has to run within the dates <a href="https://olympics.com/tokyo-2020/en/sports/surfing/">from July 25 to August 1</a>. The reason for this window? Not all waves are created equal, and organizers and surfers will wait for the best day full of the best waves to hold the competition.</p>
<p>As a recreational surfer and <a href="https://www.brandeis.edu/facultyguide/person.html?emplid=6cf46554ff6936fa51d9e22d0414e63798a5c4a1">physical oceanographer</a>, I spend a lot of time thinking about waves. But for many people, this year’s Olympics will be their first time watching the sport. They might be wondering: </p>
<p>What generates the waves that surfers will ride at the Olympics? Where do the waves come from? And why will the new Olympians be surfing at Tsurigasaki Beach?</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/412285/original/file-20210720-13-zkr21h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Lines of waves out to sea with a surfer in the foreground." src="https://images.theconversation.com/files/412285/original/file-20210720-13-zkr21h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/412285/original/file-20210720-13-zkr21h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=480&fit=crop&dpr=1 600w, https://images.theconversation.com/files/412285/original/file-20210720-13-zkr21h.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=480&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/412285/original/file-20210720-13-zkr21h.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=480&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/412285/original/file-20210720-13-zkr21h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=603&fit=crop&dpr=1 754w, https://images.theconversation.com/files/412285/original/file-20210720-13-zkr21h.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=603&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/412285/original/file-20210720-13-zkr21h.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=603&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Winds create waves that organize into an evenly spaced swell before breaking on shore.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/localsurfer/466383547/in/photolist-bFG8Wn-bqWsc-nYKNvM-qkQpqu-7zJw3K-NHDsdt-2kH5rnb-En7DLm-7zPz51-9oqKbr-adansm-ad7y6H-adamqf-dbdGGh-HdkzD-ad7x9r-2icyHFN-dd2HhH-TTfUEC-dbdNFC-dd2He2-dd2HKd-dbdKMn-adan9d-2kybhqL-fqxGi3-2kvamns-77s3b3-dbdKCZ-fjaWba-dbdNLQ-EFEm8-ztEds-5wsctT-6iVhC7-vCNim-zy8vx">Jon Bowen/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<h2>Wind creates waves</h2>
<p>Think for a few seconds about what happens when you throw a stone into a serene pond. It creates a ring of waves – depressions and elevations of the water’s surface – that spread out from the center.</p>
<p>Waves in the ocean act similarly by propagating outward from where they are generated. The key difference is that the vast majority of ocean waves are formed by wind. As the wind blows over the surface of the water, some of the energy of the wind is transferred into the water, creating waves. The biggest and most powerful wind-generated waves are produced by <a href="https://doi.org/10.3389/fmars.2019.00361">strong storms</a> that blow for a sustained period of time over a large area of the ocean. </p>
<p>The waves within a storm are usually messy and chaotic, but as they move away from the storm they grow more organized as faster waves outrun slower waves. This <a href="https://doi.org/10.1098/rsta.1948.0005">organization of the waves</a> creates “swell,” or regularly spaced lines of waves. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/412288/original/file-20210720-15-1ja01o1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A sunrise over a beach with a Japanese arch in the foreground." src="https://images.theconversation.com/files/412288/original/file-20210720-15-1ja01o1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/412288/original/file-20210720-15-1ja01o1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/412288/original/file-20210720-15-1ja01o1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/412288/original/file-20210720-15-1ja01o1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/412288/original/file-20210720-15-1ja01o1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/412288/original/file-20210720-15-1ja01o1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/412288/original/file-20210720-15-1ja01o1.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">Surfers will be competing at Tsurigasaki Beach on the east coast of Japan, where the waves break on sandbars.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:%E9%87%A3%E3%83%B6%E5%B4%8E%E6%B5%B7%E5%B2%B8%E3%81%8B%E3%82%89%E6%9C%9B%E3%82%80%E6%9D%B1%E6%B5%AA%E8%A6%8B%E3%81%AE%E9%B3%A5%E5%B1%85.jpg#/media/File:%E9%87%A3%E3%83%B6%E5%B4%8E%E6%B5%B7%E5%B2%B8%E3%81%8B%E3%82%89%E6%9C%9B%E3%82%80%E6%9D%B1%E6%B5%AA%E8%A6%8B%E3%81%AE%E9%B3%A5%E5%B1%85.jpg">Pullwell/WikimediaCommons</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<h2>Seafloors break waves</h2>
<p>As waves travel across the ocean, they don’t actually bring water with them – a wave from a storm 1,000 miles away isn’t made of water from 1,000 miles away. Waves are actually just energy moving from water molecule to water molecule. This energy doesn’t just move through the top layer of the ocean, either. Ocean waves extend far below the surface, sometimes as deep as 500 feet. When waves move into shallower water close to shore, they start to “feel” the seafloor as it pulls and drags on them, slowing them down. As seafloor gets shallower, it pushes upwards against the bottoms of waves, but the energy has to go somewhere, so the waves grow taller.</p>
<p>As the waves move toward shore, the water gets ever more shallow and the waves keep growing until, eventually, they <a href="https://youtu.be/5nCcE-jABSo">become unstable and the wave “breaks”</a> as the crest spills over toward shore.</p>
<p>It is only here, after a wave has traveled perhaps thousands of miles, that the surfing starts. To catch a wave, a surfer paddles toward shore until their speed matches that of the wave. As soon as the wave starts to break, the surfer stands up quickly and maneuvers the surf board with their feet and weight to ride the wave just ahead of the crashing lip. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/412269/original/file-20210720-17-osib4j.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A map of the Earth showing blue to red lines with a dense red area south of Japan and east of China." src="https://images.theconversation.com/files/412269/original/file-20210720-17-osib4j.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/412269/original/file-20210720-17-osib4j.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=407&fit=crop&dpr=1 600w, https://images.theconversation.com/files/412269/original/file-20210720-17-osib4j.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=407&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/412269/original/file-20210720-17-osib4j.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=407&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/412269/original/file-20210720-17-osib4j.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=512&fit=crop&dpr=1 754w, https://images.theconversation.com/files/412269/original/file-20210720-17-osib4j.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=512&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/412269/original/file-20210720-17-osib4j.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=512&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">This map shows the tracks of all the tropical storms, typhoons and hurricanes that formed from 1945 to 2006. Note the hot spot of frequent, powerful storms south of Japan.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Tropical_cyclones_1945_2006_wikicolor.png#/media/File:Tropical_cyclones_1945_2006_wikicolor.png">Citynoise/WikimediaCommons</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<h2>Waves at the Olympics</h2>
<p>The waves that surfers ride at Tsurigasaki Beach for the Olympics will be generated from one of two different types of wind: trade winds and typhoons. </p>
<p>Trade winds consistently blow around 11 to 15 mph (18 to 24 kph) in a band that stretches across the Pacific Ocean from approximately Mexico to the Philippines. These winds generate small “trade swells” that propagate northward toward the east coast of Japan and are usually <a href="https://magicseaweed.com/Shidashita-Surf-Report/2802/Historic/">a few feet tall when they arrive</a>.</p>
<p>But if the surfers and spectators are lucky, a typhoon with wind speeds greater than 74 mph (119 kph) will be supplying powerful waves for the event. Typhoons are what hurricanes are called in much of Asia and are common near Japan and China during summer and fall. Winds in a typhoon are much stronger than the trade winds. Therefore, they generate much bigger waves. Olympic surfers obviously do not want a typhoon to hit Japan. What they want is for a typhoon to form about 500 to 1,500 miles (800 to 2,400 km) to the southeast of Japan and generate big waves that will hit the coast of Japan after traveling across the ocean for one to three days.</p>
<p>Based on the current weather and surf forecasts, it looks like just such a situation will happen. As of July 22, 2021, weather models are predicting that a tropical cyclone or typhoon will <a href="https://www.surfline.com/surf-news/surf-forecast-tokyo-2020-olympics-tropical-cyclone-swell/126332">almost certainly develop</a> to the southeast of Japan over the next few days, and the winds from this storm will send a powerful swell to the Olympics. Currently, models are predicting that the waves <a href="https://www.surfline.com/surf-news/surf-forecast-tokyo-2020-olympics-tropical-cyclone-swell/126332">could be 7 feet (2.1 m) at Tsurigasaki Beach</a>, just in time for the surfing event to start.</p>
<p>Once the swell from the trade winds or a far-off typhoon reaches Tsurigasaki Beach, it is the seafloor that will determine where the waves break. Tsurigasaki Beach is a “beach break,” which means that the seafloor is sand, rather than rocks or coral reef. There are a series of human-made rock walls, <a href="https://www.nps.gov/articles/groins-and-jetties.htm">called groins</a>, sticking out perpendicularly from the beach. These have been engineered to prevent <a href="https://doi.org/10.1061/9780784400890.097">sand from moving along the beach</a> and are meant to slow erosion. These groins <a href="https://pubs.geoscienceworld.org/sepm/jsedres/article/42/2/401/96528/Coastal-processes-and-nearshore-sand-bars">create shallow sandbars a few hundred yards from shore</a> that incoming waves will break on. This is where the athletes will surf.</p>
<p>When you tune in to watch the surfing competition at the Olympics, marvel at the amazing skills of elite surfers, but remember too the far-off storms and the underwater sandbars that come together to create the beautiful waves.</p>
<p><em>Portions of this article originally appeared in an <a href="https://theconversation.com/what-makes-the-worlds-biggest-surfable-waves-150600">article</a> published on Dec. 3, 2020.</em></p><img src="https://counter.theconversation.com/content/164690/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Sally Warner 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>Olympic surfers are coming from around the world to compete in surfing’s Olympic debut. But where will the waves come from?Sally Warner, Assistant Professor of Climate Science, Brandeis UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1648552021-07-21T20:11:21Z2021-07-21T20:11:21ZWe’ve discovered an undersea volcano near Christmas Island that looks like the Eye of Sauron<figure><img src="https://images.theconversation.com/files/412372/original/file-20210721-19-iqz980.JPG?ixlib=rb-1.1.0&rect=27%2C27%2C4043%2C3124&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Phil Vandenbossche & Nelson Kuna/CSIRO</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Looking like the <a href="https://www.thetolkienforum.com/wiki/Image:eye-of-sauron-by-alex-ortiz">Eye of Sauron</a> from the Lord of the Rings Trilogy, an ancient undersea volcano was slowly revealed by multibeam sonar 3,100 metres below our vessel, 280 kilometres southeast of Christmas Island. This was on day 12 of our <a href="https://mnf.csiro.au/en/Voyages/IN2021_V04">voyage of exploration</a> to Australia’s Indian Ocean Territories, aboard CSIRO’s dedicated ocean research vessel, the <a href="https://mnf.csiro.au/en/RV-Investigator">RV Investigator</a>.</p>
<p>Previously unknown and unimagined, this volcano emerged from our screens as a giant oval-shaped depression called a caldera, 6.2km by 4.8km across. It is surrounded by a 300m-high rim (resembling Sauron’s eyelids), and has a 300 m high cone-shaped peak at its the centre (the “pupil”).</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/412368/original/file-20210721-19-1c5whs2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Sonar sea bed image" src="https://images.theconversation.com/files/412368/original/file-20210721-19-1c5whs2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/412368/original/file-20210721-19-1c5whs2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=272&fit=crop&dpr=1 600w, https://images.theconversation.com/files/412368/original/file-20210721-19-1c5whs2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=272&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/412368/original/file-20210721-19-1c5whs2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=272&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/412368/original/file-20210721-19-1c5whs2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=341&fit=crop&dpr=1 754w, https://images.theconversation.com/files/412368/original/file-20210721-19-1c5whs2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=341&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/412368/original/file-20210721-19-1c5whs2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=341&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Sonar image of the ‘Eye of Sauron’ volcano and nearby seamounts on the sea bed south-west of Christmas Island.</span>
<span class="attribution"><span class="source">Phil Vandenbossche & Nelson Kuna/CSIRO</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>A caldera is formed when a volcano collapses. The molten magma at the base of the volcano shifts upwards, leaving empty chambers. The thin solid crust on the surface of the dome then collapses, creating a large crater-like structure. Often, a small new peak then begins to form in the centre as the volcano continues spewing magma.</p>
<p>One well-known caldera is the one at <a href="https://www.livescience.com/28186-krakatoa.html">Krakatoa</a> in Indonesia, which exploded in 1883, killing tens of thousands of people and leaving only bits of the mountain rim visible above the waves. By 1927, a small volcano, Anak Krakatoa (“child of Krakatoa”), had grown in its centre. </p>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/krakatoa-is-still-active-and-we-are-not-ready-for-the-tsunamis-another-eruption-would-generate-147250">Krakatoa is still active, and we are not ready for the tsunamis another eruption would generate</a>
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<p>In contrast, we may not even be aware of volcanic eruptions when they happen deep under the ocean. One of the few tell-tale signs is the presence of <a href="https://www.abc.net.au/news/science/2020-06-03/pumice-stone-raft-transporting-marine-life/12278124">rafts of light pumice stone</a> floating on the sea surface after being blown out of a submarine volcano. Eventually, this pumice stone becomes waterlogged and sinks to the ocean floor.</p>
<p>Our volcanic “eye” was not alone. Further mapping to the south revealed a smaller sea mountain covered in numerous volcanic cones, and further still to the south was a larger, flat-topped seamount. Following our Lord of the Rings theme, we have nicknamed them <a href="https://lotr.fandom.com/wiki/Barad-d%C3%BBr">Barad-dûr</a> (“Dark Fortress”) and <a href="https://lotr.fandom.com/wiki/Ash_Mountains">Ered Lithui</a> (“Ash Mountains”), respectively. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/412388/original/file-20210721-21-w24x9u.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/412388/original/file-20210721-21-w24x9u.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=537&fit=crop&dpr=1 600w, https://images.theconversation.com/files/412388/original/file-20210721-21-w24x9u.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=537&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/412388/original/file-20210721-21-w24x9u.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=537&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/412388/original/file-20210721-21-w24x9u.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=675&fit=crop&dpr=1 754w, https://images.theconversation.com/files/412388/original/file-20210721-21-w24x9u.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=675&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/412388/original/file-20210721-21-w24x9u.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=675&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The voyage of the RV Investigator around Christmas Island.</span>
<span class="attribution"><span class="source">Tim O'Hara/Museums Victoria</span></span>
</figcaption>
</figure>
<p>Although author J.R.R. Tolkein’s knowledge of mountain geology <a href="https://www.tor.com/2017/08/01/tolkiens-map-and-the-messed-up-mountains-of-middle-earth">wasn’t perfect</a>, our names are wonderfully appropriate given the jagged nature of the first and the pumice-covered surface of the second.</p>
<p>The Eye of Sauron, Barad-dûr, and Ered Lithui are part of the Karma cluster of seamounts that have been previously estimated by <a href="https://www.livescience.com/17557-christmas-island-seamounts-mystery-solved.html">geologists</a> to be more than 100 million years old, and which formed next to an ancient sea ridge from a time when Australia was situated much further south, near Antarctica. The flat summit of Ered Lithui was formed by wave erosion when the seamount protruded above the sea surface, before the heavy seamount slowly sank back down into the soft ocean seafloor. The summit of Ered Lithui is now 2.6km below sea level.</p>
<p><img width="100%" src="https://cdn.theconversation.com/static_files/files/1720/Karma-fly.gif?1626845098"></p>
<p>But here is the geological conundrum. Our caldera looks surprisingly fresh for a structure that should be more than 100 million years old. Ered Lithui has almost 100m of sand and mud layers draped over its summit, formed by sinking dead organisms over millions of years. This sedimentation rate would have partially smothered the caldera. Instead it is possible that volcanoes have continued to sprout or new ones formed long after the original foundation. Our restless Earth is never still.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/412358/original/file-20210721-25-1jei4u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Starfish" src="https://images.theconversation.com/files/412358/original/file-20210721-25-1jei4u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/412358/original/file-20210721-25-1jei4u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/412358/original/file-20210721-25-1jei4u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/412358/original/file-20210721-25-1jei4u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/412358/original/file-20210721-25-1jei4u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/412358/original/file-20210721-25-1jei4u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/412358/original/file-20210721-25-1jei4u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The large deep-sea predatory seastar Zoroaster.</span>
<span class="attribution"><span class="source">Rob French/Museums Victoria</span>, <span class="license">Author provided</span></span>
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</figure>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/412356/original/file-20210721-23-zbhz53.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Batfish" src="https://images.theconversation.com/files/412356/original/file-20210721-23-zbhz53.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/412356/original/file-20210721-23-zbhz53.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/412356/original/file-20210721-23-zbhz53.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/412356/original/file-20210721-23-zbhz53.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/412356/original/file-20210721-23-zbhz53.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/412356/original/file-20210721-23-zbhz53.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/412356/original/file-20210721-23-zbhz53.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">Small batfish patrol the seamount summits.</span>
<span class="attribution"><span class="source">Rob French/Museums Victoria</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/412355/original/file-20210721-25-ax5rh6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Sea pig" src="https://images.theconversation.com/files/412355/original/file-20210721-25-ax5rh6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/412355/original/file-20210721-25-ax5rh6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/412355/original/file-20210721-25-ax5rh6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/412355/original/file-20210721-25-ax5rh6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/412355/original/file-20210721-25-ax5rh6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/412355/original/file-20210721-25-ax5rh6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/412355/original/file-20210721-25-ax5rh6.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">Elasipod sea cucumbers feed on organic detritus on deep sandy seafloors.</span>
<span class="attribution"><span class="source">Rob French/Museums Victoria</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>But life adapts to these geological changes, and Ered Lithui is now covered in seafloor animals. Brittle-stars, sea-stars, crabs and worms burrow into or skate over the sandy surface. Erect black corals, fan-corals, sea-whips, sponges and barnacles grow on exposed rocks. Gelatinous cusk-eels prowl around rock gullies and boulders. Batfish lie in wait for unsuspecting prey.</p>
<p>Our mission is to map the seafloor and survey sea life from these ancient and secluded seascapes. The Australian government recently announced plans to create two massive marine parks across the regions. Our expedition will supply scientific data that will help Parks Australia to manage these areas into the future. </p>
<p>Scientists from museums, universities, CSIRO and Bush Blitz around Australia are participating in the voyage. We are close to completing part one of our journey to the Christmas Island region. Part two of our journey to the Cocos (Keeling) Island region will be scheduled in the next year or so.</p>
<p>No doubt many animals that we find here will be new to science and our first records of their existence will be from this region. We expect many more surprising discoveries.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/this-deep-sea-creature-is-long-armed-bristling-with-teeth-and-the-sole-survivor-of-180-million-years-of-evolution-162842">This deep-sea creature is long-armed, bristling with teeth, and the sole survivor of 180 million years of evolution</a>
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<img src="https://counter.theconversation.com/content/164855/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The voyage of exploration on the RV Investigator was facilitated by a grant of sea time by the CSIRO Marine National Facility, and funding from Parks Australia and Bush Blitz, both part of the Commonwealth Department of Agriculture, Water and Environment. </span></em></p>Sonar scans of the Indian Ocean floor south of Christmas Island have revealed a Tolkeinesque landscape of towering peaks, ashen uplands and ominous volcanic craters.Tim O'Hara, Senior Curator of Marine Invertebrates, Museums Victoria Research InstituteLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1601722021-05-03T08:16:34Z2021-05-03T08:16:34ZWhat are ‘internal waves’ that possibly sank the Indonesian sub? If you’ve ever suffered plane turbulence, you’ve been inside one<figure><img src="https://images.theconversation.com/files/398283/original/file-20210503-15-1aem3te.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C4256%2C2446&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Sumburgh_Waves_IMG_5087_(28622722710).jpg">Ronnie Robertson/Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>Last week might have been the first time you ever heard of “internal waves” — the phenomenon suspected of <a href="https://www.abc.net.au/news/science/2021-05-01/indonesian-sunken-submarine-internal-waves-what-do-we-know/100107196">causing the tragic sinking</a> of the Indonesian submarine KRI Nanggala the previous week, resulting in the deaths of the 53 crew members.</p>
<p>So it may surprise you to learn that you’ve doubtless encountered internal waves before. They exist all around us in the atmosphere and ocean, although they are usually invisible. If you’ve ever been on an aeroplane experiencing turbulence, you’ve felt their effects.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/398260/original/file-20210503-24-151jehm.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Satellite image showing atmospheric and oceanic waves" src="https://images.theconversation.com/files/398260/original/file-20210503-24-151jehm.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/398260/original/file-20210503-24-151jehm.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=519&fit=crop&dpr=1 600w, https://images.theconversation.com/files/398260/original/file-20210503-24-151jehm.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=519&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/398260/original/file-20210503-24-151jehm.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=519&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/398260/original/file-20210503-24-151jehm.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=652&fit=crop&dpr=1 754w, https://images.theconversation.com/files/398260/original/file-20210503-24-151jehm.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=652&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/398260/original/file-20210503-24-151jehm.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=652&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Satellite image of internal waves in the atmosphere and ocean off the northwest coast of Australia. In the atmosphere we see the waves as lines of clouds. In the ocean, the waves appear in reflections of the suns rays off the sea surface.</span>
<span class="attribution"><span class="source">NASA</span></span>
</figcaption>
</figure>
<p>Internal waves are generated when a strong wind passes over a steep hill. Air is lifted up and over the hill against the force of gravity, and then accelerates down the other side as gravity takes over. This up-and-down motion kicks off an oscillation downwind of the hill. The oscillating motion is an internal wave. </p>
<p>You can visualise this more easily by imagining a bouncy ball rolling off a step on an otherwise level floor. If you roll it fast enough, the ball takes flight at the crest of the step and accelerates downwards under gravity. When the ball hits the ground it starts to bounce with a bounce-length (or wavelength) that depends on how fast you rolled it.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/398261/original/file-20210503-16-zxzk1z.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/398261/original/file-20210503-16-zxzk1z.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/398261/original/file-20210503-16-zxzk1z.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/398261/original/file-20210503-16-zxzk1z.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/398261/original/file-20210503-16-zxzk1z.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=565&fit=crop&dpr=1 754w, https://images.theconversation.com/files/398261/original/file-20210503-16-zxzk1z.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=565&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/398261/original/file-20210503-16-zxzk1z.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=565&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Internal waves are generated by fast flow over a steep hill, much like a ball bounces when rolled at speed off a step.</span>
</figcaption>
</figure>
<p>Unsurprisingly, atmospheric internal waves are most often found in mountainous regions. If you’ve ever looked up at the sky and seen long parallel bands of clouds, particularly near mountains, you’ve probably seen an internal wave propagating through the atmosphere. The waves propagate upwards at the same time as they are carried downwind of the mountain by the air flow.</p>
<p>The waves can reach all the way into the stratosphere, which begins <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2001RG000106">roughly 10 kilometres above the ground</a>, before changes in the atmospheric structure force the waves to break. Just as waves break on the beach as the water becomes shallower, internal waves break in the atmosphere when the properties of the air (such as flow speed or density) change rapidly with height. Such changes are common in the lower stratosphere (10-15km), which is where jet airliners fly.</p>
<p>And just like waves at the beach, this breaking creates a huge amount of chaotic motion - or turbulence - creating an unpleasant jolting motion for any aircraft (and their passengers) that happen to be in the vicinity!</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"846842493001879554"}"></div></p>
<p>So what about internal waves in the ocean? Just like in the atmosphere, they are generated by strong flows (in this case, ocean currents) over steep hills. But in this case the hills are on the seafloor. </p>
<p>The steeper the hills and the stronger the currents, the bigger the resulting waves. The seas around Indonesia have a <a href="https://www.internalwaveatlas.com/Atlas2_PDF/IWAtlas2_Pg453_Indonesia.pdf">perfect combination of these ingredients</a>: a network of deep basins connected by narrow, shallow channels, through which strong tidal currents flow. </p>
<p><img src="https://cdn.theconversation.com/static_files/files/1556/ezgif-6-6911622f3796.gif?1620029157" width="100%"></p>
<p>These currents are so strong they generate a particularly extreme kind of internal wave known as an “internal solitary wave”, which concentrates the entire wave energy into a single up-and-down motion, rather than many individual oscillations. These waves can be <a href="https://www.nature.com/articles/srep30041">hundreds of metres high</a>, several kilometres long, and <a href="https://journals.ametsoc.org/view/journals/phoc/30/9/1520-0485_2000_030_2172_solais_2.0.co_2.xml">travel at speeds of 10km per hour</a>.</p>
<p>Solitary waves are biggest at depths of around 50-200 metres, where there is a sharp temperature gradient between the warm surface layer and the cool ocean interior — the same depths at which submarines typically operate. If a submarine sitting at this kind of depth were suddenly hit by one of these waves, it would be carried downwards (or upwards, depending on its position relative to the wave) at a rate of perhaps 10 metres per minute for 10 minutes. </p>
<p><img src="https://cdn.theconversation.com/static_files/files/1552/soliton.gif?1620014156" width="100%"></p>
<p>Without swift action to counteract the wave motion, a submarine could quickly be carried below its maximum operational depth, leading to hull failure and sinking. An <a href="https://apps.dtic.mil/dtic/tr/fulltext/u2/632010.pdf">archive US Navy report</a> reveals submarine commanders were aware of the risks of internal waves as long ago as 1966.</p>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/indonesian-submarine-found-what-might-have-happened-to-the-kri-nanggala-in-its-final-moments-159703">Indonesian submarine found: what might have happened to the KRI Nanggala in its final moments?</a>
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<p>Besides the danger they pose to submarines, internal waves also play an <a href="https://www.nature.com/articles/s43017-020-0097-z">important role in ocean circulation</a>. They carry vast quantities of energy, helping to sustain ocean currents, mixing heat and carbon dioxide through the oceans, and thus influencing our global climate. </p>
<p>So next time you’re jolted by turbulence on a plane, or looking up at some strange stripes of cloud in the sky, give some thought to the internal waves propagating all around you.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/satellites-reveal-ocean-currents-are-getting-stronger-with-potentially-significant-implications-for-climate-change-159461">Satellites reveal ocean currents are getting stronger, with potentially significant implications for climate change</a>
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</em>
</p>
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<img src="https://counter.theconversation.com/content/160172/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Callum Shakespeare receives funding from the Australian Research Council Discovery Program and the Australian National University to pursue research related to internal waves and their role in the climate system.</span></em></p>Internal waves can create pretty cloud shapes in the sky, as well as making life unpleasant for passengers on aeroplanes. And in the oceans they can be a deadly hazard to submarines.Callum Shakespeare, Senior Lecturer in Climate and Fluid Physics, Australian National UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1579112021-04-07T18:30:53Z2021-04-07T18:30:53ZThe ocean is becoming more stable – here’s why that might not be a good thing<p>If you’ve ever been seasick, “stable” may be the last word you associate with the ocean. But as global temperatures rise, the world’s oceans are technically becoming more stable.</p>
<p>When scientists talk about ocean stability, they refer to how much the different layers of the sea mix with each other. A recent study analysed over a million samples and found that, over the past five decades, the stability of the ocean increased at a rate that was <a href="https://www.nature.com/articles/s41586-021-03303-x">six times faster</a> than scientists were anticipating.</p>
<hr>
<iframe id="noa-web-audio-player" style="border: none" src="https://embed-player.newsoveraudio.com/v4?key=x84olp&id=https://theconversation.com/the-ocean-is-becoming-more-stable-heres-why-that-might-not-be-a-good-thing-157911&bgColor=F5F5F5&color=D8352A&playColor=D8352A" width="100%" height="110px"></iframe>
<p><em>You can listen to more articles from The Conversation, narrated by Noa, <a href="https://theconversation.com/uk/topics/audio-narrated-99682">here</a>.</em></p>
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<p>Ocean stability is an important regulator of the global climate and the productivity of marine ecosystems which feed a substantial portion of the world’s people. It controls how heat, carbon, nutrients and dissolved gases are exchanged between the upper and lower layers of the ocean. </p>
<p>So while a more stable ocean might sound idyllic, the reality is less comforting. It could mean the upper layer trapping more heat, and containing less nutrients, with a big impact on ocean life and the climate.</p>
<h2>How the oceans circulate heat</h2>
<p>Sea surface temperatures get colder the further you travel from the equator towards the poles. It’s a simple point, but it has enormous implications. Because temperature, along with salinity and pressure, controls the density of seawater, this means that the ocean surface also becomes denser as you move away from the tropics. </p>
<p>Seawater density increases with depth too, because the sunlight that warms the ocean is absorbed at the surface, whereas the deep ocean is full of cold water. The change in density with depth is referred to by oceanographers as stability. The faster density increases with depth, the more stable the ocean is said to be.</p>
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<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/369797/original/file-20201117-13-180ibt9.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/369797/original/file-20201117-13-180ibt9.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/369797/original/file-20201117-13-180ibt9.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/369797/original/file-20201117-13-180ibt9.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/369797/original/file-20201117-13-180ibt9.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=504&fit=crop&dpr=1 754w, https://images.theconversation.com/files/369797/original/file-20201117-13-180ibt9.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=504&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/369797/original/file-20201117-13-180ibt9.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=504&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p><strong><em>This story is part of <a href="https://theconversation.com/uk/topics/oceans-21-96784">Oceans 21</a></em></strong>
<br><em>Our series on the global ocean opened with <a href="https://oceans21.netlify.app/">five in-depth profiles</a>. Look out for new articles on the state of our oceans in the lead up to the UN’s next climate conference, COP26. The series is brought to you by The Conversation’s international network</em>.</p>
<hr>
<p>It helps to think of the ocean as divided into two layers, each with different levels of stability.</p>
<p>The surface mixed layer occupies the upper (roughly) 100 metres of the ocean and is where heat, freshwater, carbon and dissolved gases are exchanged with the atmosphere. Turbulence whipped up by the wind and waves at the sea surface mixes all the water together.</p>
<p>The lowest layer is called the abyss, which extends from a few hundred metres depth to the seafloor. It’s cold and dark, with weak currents slowly circulating water around the planet that remains isolated from the surface for decades or even centuries.</p>
<p>Dividing the abyss and the surface mixed layer is something called the pycnocline. We can think of it like a layer of cling film (or Saran Wrap). It’s invisible and flexible, but it stops water moving through it. When the film is ripped into shreds, which happens in the ocean when turbulence effectively pulls the pycnocline apart, water can leak through in both directions. But as global temperatures rise and the ocean’s surface layer absorbs more heat, the pycnocline is becoming more stable, making it harder for water at the ocean’s surface and in the abyss to mix.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/393819/original/file-20210407-19-12vce43.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two jellyfish swim near a hazy layer of ocean water." src="https://images.theconversation.com/files/393819/original/file-20210407-19-12vce43.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/393819/original/file-20210407-19-12vce43.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=449&fit=crop&dpr=1 600w, https://images.theconversation.com/files/393819/original/file-20210407-19-12vce43.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=449&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/393819/original/file-20210407-19-12vce43.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=449&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/393819/original/file-20210407-19-12vce43.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=565&fit=crop&dpr=1 754w, https://images.theconversation.com/files/393819/original/file-20210407-19-12vce43.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=565&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/393819/original/file-20210407-19-12vce43.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=565&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Moon jellyfishes disturb the pycnocline in a Swedish fjord.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Pycnocline#/media/File:Moon_jellyfishes_disturbing_the_top_water_layer_of_Gullmarn_fjord_1.jpg">W. Carter/Wikipedia</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Why is that a problem? Well, there’s an invisible conveyor belt of seawater which moves warm water from the equator to the poles, where it’s cooled and becomes more dense and so sinks, returning back to the equator at depth. During this journey, the heat absorbed at the ocean’s surface is moved to the abyss, helping redistribute the ocean’s heat burden, accumulated from an atmosphere that’s rapidly warming due to our greenhouse gas emissions.</p>
<p>If a stabler pycnocline traps more heat in the surface of the ocean, it could disrupt how effectively the ocean absorbs excess heat and pile pressure on sensitive shallow-water ecosystems like coral reefs.</p>
<h2>Increasing stability causes a nutrient drought</h2>
<p>And just as the ocean surface contains heat that must be mixed downwards, the abyss contains an enormous reservoir of nutrients that need to be mixed upwards. </p>
<p>The building blocks of most marine ecosystems are phytoplankton: microscopic algae which use photosynthesis to make their own food and absorb vast quantities of CO₂ from the atmosphere, as well as <a href="https://oceanservice.noaa.gov/facts/ocean-oxygen.html">produce most of the world’s oxygen</a>.</p>
<p>Phytoplankton can only grow when there is enough light and nutrients. During spring, sunshine, longer days and lighter winds allow a seasonal pycnocline to form near the surface. Any available nutrients trapped above this pycnocline are quickly used up by the phytoplankton as they grow in what is called the spring bloom.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/393815/original/file-20210407-23-13fjae3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A satellite image depicting a bright blue plume off the south-west coast of England." src="https://images.theconversation.com/files/393815/original/file-20210407-23-13fjae3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/393815/original/file-20210407-23-13fjae3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=480&fit=crop&dpr=1 600w, https://images.theconversation.com/files/393815/original/file-20210407-23-13fjae3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=480&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/393815/original/file-20210407-23-13fjae3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=480&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/393815/original/file-20210407-23-13fjae3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=603&fit=crop&dpr=1 754w, https://images.theconversation.com/files/393815/original/file-20210407-23-13fjae3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=603&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/393815/original/file-20210407-23-13fjae3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=603&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">An algal bloom off the coast of south-west England.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Phytoplankton#/media/File:Cwall99_lg.jpg">Andrew Wilson and Steve Groom/NASA</a></span>
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</figure>
<p>For phytoplankton at the surface to keep growing, the nutrients from the abyss must cross the pycnocline. And so another problem emerges. If phytoplankton are starved of nutrients thanks to a strengthened pycnocline then there’s less food for the vast majority of ocean life, starting with the tiny microscopic animals which eat the algae and the small fish which eat them, and moving all the way up the food chain to sharks and whales. </p>
<p>Just as a more stable ocean is less effective at shifting heat into the deep sea and regulating the climate, it’s also worse at sustaining the vibrant food webs at the sunlit surface which society depends on for nourishment.</p>
<h2>Should we be worried?</h2>
<p>Ocean circulation is constantly evolving with natural variations and human-induced changes. The increasing stability of the pycnocline is just one part of an extremely complex puzzle that oceanographers are striving to solve.</p>
<p>To predict future changes in our climate, we use numerical models of the ocean and atmosphere that must include all of the physical processes responsible for changing them. We simply don’t have computers powerful enough to include the effects of small-scale, turbulent processes within a model that simulates conditions over a global scale.</p>
<p>We do know that human activity is having a greater than expected impact on fundamental aspects of our planet’s systems though. And we may not like the consequences.</p><img src="https://counter.theconversation.com/content/157911/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Phil Hosegood does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Climate change is strengthening the division between the ocean surface and the abyss.Phil Hosegood, Associate Professor in Physical Oceanography, University of PlymouthLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1551822021-02-26T14:56:26Z2021-02-26T14:56:26ZWhere does plastic pollution go when it enters the ocean?<figure><img src="https://images.theconversation.com/files/386646/original/file-20210226-23-196xux1.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C5000%2C3330&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://unsplash.com/photos/5fbJMCzqNDs">Brian Yurasits/Unsplash</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>Of the hundreds of millions of tonnes of plastic waste we produce each year, it’s estimated that around <a href="https://dx.doi.org/10.1126/science.1260352">ten million tonnes</a> enters the ocean. Roughly half of the plastics produced are less dense than water, and so they float. But scientists estimate that there are only about <a href="https://doi.org/10.1088/1748-9326/ab6d7d">0.3 million tonnes</a> of plastic floating at the ocean surface, so where is the rest of it going?</p>
<p>Consider the journey of a plastic fibre that’s shed from your fleece. A heavy rain washes it into a storm drain or a nearby river. Does the tiny fibre settle there? Or does the river carry it out to the coast where it lingers on the seabed? Or does it continue to float further out – finally ending up in the vast open ocean? </p>
<p>The dizzying variety of forms plastic waste can take means that a fibre’s fate is just one mystery among countless others.</p>
<p>Finding out where all the missing plastic ends up can help us figure out which parts of the ocean are most affected by this type of pollution – and where to focus clean-up efforts. But to do that, we need to be able to predict the pathways of different kinds of plastic, which requires large teams of physicists, biologists and mathematicians working together. </p>
<p>That’s what our research team is doing. Here’s what we’ve learned so far.</p>
<h2>Plastic pathways</h2>
<p>We already know that large pieces of plastic, like bottles, can float on the sea surface for years, if not centuries, taking a long time to break down. Currents, winds and waves can, after a journey of several years, bring them to the centre of ocean basins, where they accumulate in 1,000km-wide circulating systems known as gyres. The vast “<a href="https://doi.org/10.1088/1748-9326/7/4/044040">garbage patches</a>” that result resemble more of a soup of plastic than an island of trash.</p>
<hr>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/369797/original/file-20201117-13-180ibt9.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/369797/original/file-20201117-13-180ibt9.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/369797/original/file-20201117-13-180ibt9.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/369797/original/file-20201117-13-180ibt9.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/369797/original/file-20201117-13-180ibt9.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=504&fit=crop&dpr=1 754w, https://images.theconversation.com/files/369797/original/file-20201117-13-180ibt9.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=504&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/369797/original/file-20201117-13-180ibt9.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=504&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption"></span>
</figcaption>
</figure>
<p><strong><em>This story is part of <a href="https://theconversation.com/uk/topics/oceans-21-96784">Oceans 21</a></em></strong>
<br><em>Our series on the global ocean opened with <a href="https://oceans21.netlify.app/">five in-depth profiles</a>. Look out for new articles on the state of our oceans in the lead up to the UN’s next climate conference, COP26. The series is brought to you by The Conversation’s international network.</em></p>
<hr>
<p>But the fate of plastic fibres – perhaps the smallest plastic fragments to reach the ocean – is more complex. Large fibres can break up over days and weeks into even smaller pieces, due to turbulence from breaking waves and ultraviolet radiation from the sun. These are called microplastics, and they range in size from five millimetres to specks smaller than bacteria. </p>
<p>Microplastics can be eaten by fish – it’s estimated that <a href="https://www.scientificamerican.com/article/from-fish-to-humans-a-microplastic-invasion-may-be-taking-a-toll/">one in three fish</a> eaten by humans contains microplastics. Tinier particles can also be consumed by zooplankton – microscopic animals that float at the surface – which are then eaten by even larger animals, including whales. </p>
<p>Microorganisms can grow on the surface of microplastics too, in a process known as “biofouling” that causes them to sink. Muddy rivers, like the Mississippi or the Amazon, contain clays that <a href="https://dx.doi.org/10.1007/s10652-014-9365-0">settle rapidly</a> when they come into contact with salty ocean water. Microplastics can be carried down by the settling clay, but how much this happens exactly is unknown.</p>
<figure class="align-center ">
<img alt="Seawater filled with tiny plastic particles and fibres." src="https://images.theconversation.com/files/386658/original/file-20210226-15-1o3gdqm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/386658/original/file-20210226-15-1o3gdqm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/386658/original/file-20210226-15-1o3gdqm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/386658/original/file-20210226-15-1o3gdqm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/386658/original/file-20210226-15-1o3gdqm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/386658/original/file-20210226-15-1o3gdqm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/386658/original/file-20210226-15-1o3gdqm.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">Microplastics are often formed from larger plastic objects that break up in the ocean.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/microplastics-mediterran-sea-1115773922">Dirk Wahn/Shutterstock</a></span>
</figcaption>
</figure>
<p>Quantifying all these outcomes for each bit of plastic is an enormous challenge. What fraction ends up in fish, carried down by clay or covered in microbial slime on the sea bed? Of the fraction of plastics which make it all the way out to the open ocean, it’s unclear how long it takes for biofouling or other forces to pull the particles well below the surface to begin their long, final descent to the sea floor.</p>
<p>With all these complicating factors, it may seem hopeless to predict where plastics ultimately end up. But we’re slowly making progress.</p>
<h2>Catching a wave</h2>
<p>If you have ever been on a boat in choppy waters, you might think you’re just bobbing up and down in the same spot. But you’re actually moving very slowly in the direction of the waves. This is a phenomenon known as <a href="https://royalsocietypublishing.org/doi/10.1098/rsta.2017.0104">the Stokes drift</a>, and it affects floating plastics too. </p>
<p>For particles smaller than 0.1 millimetres, moving through seawater is like us wading through honey. But the viscosity of seawater has less of an influence on plastics larger than one millimetre. Each wave gives these bigger particles an extra push in its direction. According to preliminary research that’s currently under review, this might mean larger plastics are carried out to sea <a href="https://arxiv.org/abs/2102.09836">much faster</a> than tiny microplastics, making them less likely to settle in parts of the ocean where more marine life is found – around coasts.</p>
<figure class="align-center ">
<img alt="Waves at the ocean surface." src="https://images.theconversation.com/files/386660/original/file-20210226-19-z37u4k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/386660/original/file-20210226-19-z37u4k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/386660/original/file-20210226-19-z37u4k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/386660/original/file-20210226-19-z37u4k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/386660/original/file-20210226-19-z37u4k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/386660/original/file-20210226-19-z37u4k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/386660/original/file-20210226-19-z37u4k.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 size and shape of a plastic particle can decide how far and fast waves transport it.</span>
<span class="attribution"><a class="source" href="https://unsplash.com/photos/tt2Oui1hKAM">Matt Hardy/Unsplash</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>This research involved studying spherical plastic particles, but microplastic waste comes in all kinds of shapes and sizes, including disks, rods and flexible fibres. How do waves influence where they end up? </p>
<p>A recent study found that non-spherical particles align themselves with the direction of waves, which can <a href="https://doi.org/10.1103/PhysRevFluids.4.034301">slow the rate</a> at which they sink. <a href="https://dx.doi.org/10.1103/PhysRevFluids.5.124301">Lab experiments</a> have further shown how the shape of each plastic particle affects how far it’s transported. Less spherical particles are more likely to go further from coasts.</p>
<p>Solving the mystery of the missing plastics is a science in its infancy. The ability of waves to transport large microplastics faster than previously thought helps us understand why they are now found throughout the world’s oceans, including <a href="https://theconversation.com/theyre-everywhere-new-study-finds-polyester-fibres-throughout-the-arctic-ocean-152881">in the Arctic</a> and <a href="https://theconversation.com/pristine-antarctic-fjords-contain-similar-levels-of-microplastics-to-open-oceans-near-big-civilisations-91360">around Antarctica</a>. But finding the fibre that was pulled from your fleece is still more challenging than finding a needle in a haystack.</p>
<p>
<section class="inline-content">
<img src="https://images.theconversation.com/files/379355/original/file-20210118-15-1ttgn0o.png?h=128">
<div>
<header>Professor Bruce Sutherland, University of Alberta, leads the research project:</header>
<p><a href="https://wun.ac.uk/wun/research/view/modelling-microplastic-waste-transport-in-rivers-and-the-coastal-oceans">Modelling Microplastic Waste Transport in Rivers and the Coastal Oceans</a></p>
<footer>Worldwide University Network provides funding as a content partner of The Conversation UK</footer>
</div>
</section>
</p><img src="https://counter.theconversation.com/content/155182/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Bruce Sutherland receives funding from the Natural Sciences and Engineering Research Council of Canada, the Worldwide Universities Network and the University of Alberta.</span></em></p><p class="fine-print"><em><span>Michelle DiBenedetto receives funding from the National Science Foundation and from Woods Hole Oceanographic Institution Postdoctoral Scholarship.</span></em></p><p class="fine-print"><em><span>Ton van den Bremer receives funding from the Worldwide Universities Network and the Royal Academy of Engineering.</span></em></p>Each bit of plastic takes a unique journey once it reaches the ocean. We’re trying to spot the patterns.Bruce Sutherland, Professor of Physics, University of AlbertaMichelle DiBenedetto, Assistant Professor of Mechanical Engineering, University of WashingtonTon van den Bremer, Associate Professor of Engineering, Delft University of TechnologyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1540202021-02-02T15:19:41Z2021-02-02T15:19:41ZGalápagos: we’ve found out why the islands are blessed with such nutrient-rich waters<figure><img src="https://images.theconversation.com/files/381720/original/file-20210201-23-43mwo4.jpg?ixlib=rb-1.1.0&rect=0%2C5%2C3866%2C2579&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Javarman / shutterstock</span></span></figcaption></figure><p>Every part of the Galápagos’s exceptional and distinctive ecosystem can be traced back to its rich reserves of marine algae. Some animals feed on the microscopic plants directly, others, in turn, feast on them, and so on. Many unique species found only on the Pacific archipelago such as the famous marine iguanas or flightless cormorants, ultimately get their food from this algae. </p>
<p>The abundance of algae – technically microscopic plants known as phytoplankton – is a result of a pool of unusually cold water that is often found to the west of the islands. This cold pool is a result of an upwelling of nutrient-rich deep ocean waters, which is weakest during the hot wet season (December to May) and strongest during the dry Garúa season (May to November).</p>
<p>Scientists have speculated for decades about what drives this Galápagos upwelling and, in the absence of conclusive evidence, some have inferred it is driven by an eastward-flowing current <a href="https://doi.org/10.1175/JPO-D-19-0110.1">colliding with the islands</a>. </p>
<p>But the key to unlocking the mystery of what causes the upwelling lies in its strong seasonality. First, we found that the coldness of the water to the west of the islands is connected to the strength of local northward winds. This is in marked contrast to the weaker upwelling that occurs throughout the wider equatorial Pacific Ocean, which is sustained by the strength of the prevailing westward winds.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/381981/original/file-20210202-23-n6gpu8.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="World map. Land is grey, sea is blue and green" src="https://images.theconversation.com/files/381981/original/file-20210202-23-n6gpu8.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/381981/original/file-20210202-23-n6gpu8.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=366&fit=crop&dpr=1 600w, https://images.theconversation.com/files/381981/original/file-20210202-23-n6gpu8.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=366&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/381981/original/file-20210202-23-n6gpu8.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=366&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/381981/original/file-20210202-23-n6gpu8.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=460&fit=crop&dpr=1 754w, https://images.theconversation.com/files/381981/original/file-20210202-23-n6gpu8.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=460&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/381981/original/file-20210202-23-n6gpu8.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=460&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Global map of chlorophyll (a measure of phytoplankton growth). The Galápagos sits in a current that sends nutrients through the ‘desert’ of the Pacific Ocean.</span>
<span class="attribution"><a class="source" href="https://earthobservatory.nasa.gov/global-maps/MY1DMM_CHLORA">NASA</a></span>
</figcaption>
</figure>
<p>But how exactly do these northward winds drive strong localised upwelling around the Galápagos? We recently explored this question for a study now published in <a href="https://www.nature.com/articles/s41598-020-80609-2">Scientific Reports</a>, in which we used a realistic, high-resolution computer model of ocean circulation in the region. We wanted the model to focus specifically on the effects of local wind strength, excluding as far as possible larger scale variables. This meant we modelled the ocean in its typical annual-mean state for factors like temperature, salinity and water velocity, and then “forced” it with six-hourly changes in atmospheric wind, radiation, precipitation and evaporation based on real-world observations. </p>
<p>To our surprise, this much simplified model was capable of closely reproducing the actual seasonal cycle of the Galápagos cold pool. Close analysis then pinpointed intense turbulent mixing in the ocean as the precise cause of the upwelling. What appears to be happening, to the west of the islands, is northward winds are blowing on so-called upper-ocean fronts – these are bands of abrupt lateral changes in seawater temperature, akin to but much smaller than atmospheric fronts in weather maps. When the wind hits the fronts, this mixes the warm surface water with cooler waters below, and provokes further circulation below the surface which draws still colder water up from the depths of the ocean.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/381975/original/file-20210202-21-1w2onpp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A turtle with small colourful fish" src="https://images.theconversation.com/files/381975/original/file-20210202-21-1w2onpp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/381975/original/file-20210202-21-1w2onpp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=398&fit=crop&dpr=1 600w, https://images.theconversation.com/files/381975/original/file-20210202-21-1w2onpp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=398&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/381975/original/file-20210202-21-1w2onpp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=398&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/381975/original/file-20210202-21-1w2onpp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=500&fit=crop&dpr=1 754w, https://images.theconversation.com/files/381975/original/file-20210202-21-1w2onpp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=500&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/381975/original/file-20210202-21-1w2onpp.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"></a>
<figcaption>
<span class="caption">Nutrient-rich water supports lots of spectacular marine life.</span>
<span class="attribution"><span class="source">Longjourneys / shutterstock</span></span>
</figcaption>
</figure>
<p>The cold-pool upwelling is highly productive, since more nutrients mean more phytoplankton which means more fish, and so on. The reproductive success of the Galápagos fur seal, Galápagos penguin, flightless cormorant and many other endemic species, is highly dependent upon this upwelling. The seasonal presence of endangered filter-feeding <a href="https://theconversation.com/whale-sharks-gather-at-a-few-specific-locations-around-the-world-now-we-know-why-98502">whale sharks</a> in the area is likely also related to these processes. Furthermore, Ecuador’s industrial tuna fleet, one of the largest in the world, concentrates on this region, as does the semi-industrial mainland-based longline fleet. </p>
<p>We then played with the exact location of the islands and their shape within our model. This confirmed that the Galápagos archipelago is almost perfectly positioned to maximise the strength of the wind-generated mixing. Without the upwelling generated by the mixing, phytoplankton growth around the islands would be closer to the more modest levels found much further west in the Pacific. And if this was the case, it would be much harder for the Galápagos to sustain its unique wealth of endemic species.</p>
<p>Our findings demonstrate that Galápagos upwelling is at the very least likely to be strongly influenced by highly localised interactions between the atmosphere and the ocean. This new knowledge will inform plans to expand the archipelago’s <a href="https://www.galapagosislands.com/blog/galapagos-marine-reserve-marine-sanctuary/">marine reserve</a> and help protect against the mounting pressures of climate change and <a href="https://theconversation.com/galapagos-how-to-protect-the-islands-amazing-marine-life-from-huge-chinese-fishing-fleets-144927">human exploitation</a>.</p><img src="https://counter.theconversation.com/content/154020/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Alex Forryan received funding from the Royal Society.</span></em></p><p class="fine-print"><em><span>Alberto Naveira Garabato receives funding from the Royal Society and Wolfson Foundation. </span></em></p><p class="fine-print"><em><span>Alex Hearn receives funding from the Royal Society, PEW Charitable Trust and Galapagos Conservation Trust. He is affiliated with MigraMar, the Galapagos Whale Shark Project, Turtle Island Restoration Network and Fundación Megafauna Marina del Ecuador. </span></em></p>How Pacific winds interact with the sea to bring colder waters up from the depths.Alex Forryan, Research Fellow, National Oceanography Centre, University of SouthamptonAlberto Naveira Garabato, Professor, National Oceanography Centre, University of SouthamptonAlex Hearn, Professor, School of Biological and Environmental Sciences, Universidad San Francisco de Quito (Ecuador)Licensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1516622020-12-08T19:08:25Z2020-12-08T19:08:25ZHow universities and professions are preparing to meet the climate challenge<p>Getting ahead of climate change challenges is now a pressing need across our economy and society. Last month the bosses of 22 of Australia’s largest firms, including BHP, Rio Tinto, Wesfarmers and Commonwealth Bank, <a href="https://www.afr.com/policy/energy-and-climate/top-ceos-form-exclusive-climate-change-club-20201125-p56hvo">put their names</a> to the <a href="https://www.climateleaders.org.au/">Climate Leaders Coalition</a>. It signalled their collective wish to push down emissions and push up their international obligations under the Paris Agreement.</p>
<p>Australia’s politicians are increasingly on the back foot — something universities and professions cannot risk. The cockpit of the knowledge economy must remain fit for purpose in the face of global challenges. </p>
<p>The biggest of these of late has been marshalling expertise to tackle a global pandemic. Climate change is an even bigger challenge.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/climate-change-is-the-most-important-mission-for-universities-of-the-21st-century-139214">Climate change is the most important mission for universities of the 21st century</a>
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<p>Universities as knowledge communities take pride in leading discovery and understanding. The pressures to update and reform can come from beyond the academy, sometimes in response to perceived failure (think of economics and the GFC) or in meeting demand for new skills (the rapid expansion of business education in the past two decades).</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/373524/original/file-20201208-19-1qk8khm.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Cover of The Preparedness Report" src="https://images.theconversation.com/files/373524/original/file-20201208-19-1qk8khm.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/373524/original/file-20201208-19-1qk8khm.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=792&fit=crop&dpr=1 600w, https://images.theconversation.com/files/373524/original/file-20201208-19-1qk8khm.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=792&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/373524/original/file-20201208-19-1qk8khm.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=792&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/373524/original/file-20201208-19-1qk8khm.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=996&fit=crop&dpr=1 754w, https://images.theconversation.com/files/373524/original/file-20201208-19-1qk8khm.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=996&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/373524/original/file-20201208-19-1qk8khm.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=996&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="attribution"><a class="source" href="https://www.uwa.edu.au/institutes/public-policy/-/media/Public-Policy/Documents/Preparedness-report-WEB.pdf">UWA Public Policy Institute</a>, <span class="license">Author provided</span></span>
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<p><a href="https://www.uwa.edu.au/institutes/public-policy/-/media/Public-Policy/Documents/Preparedness-report-WEB.pdf">The Preparedness Report</a>, launched today by the UWA Public Policy Institute, argues disciplines, and the practitioners they educate and train, are already changing fast in response to climate change. </p>
<p>The report highlights the nature and extent of retooling in six fields: engineering, architecture, law, economics, healthcare and oceanography (the same is true for around 20 more disciplines).</p>
<h2>Key questions for all professions</h2>
<p>All professions need to find timely answers to some core questions:</p>
<ul>
<li><p>What will be the practical impacts of climate change on the feasibility, processes, sustainability and operations of their professions?</p></li>
<li><p>How will future members of the professions need to be educated, trained and accredited?</p></li>
<li><p>How will the underlying disciplines change?</p></li>
<li><p>Which new fields of research and education will emerge?</p></li>
<li><p>How will different disciplines develop new cross-overs and synergies?</p></li>
</ul>
<p>Many new skills and competencies will have to be taught. Think, for example, of the need to engineer heat-tolerant public transport systems and plan water-sensitive cities. </p>
<p>Fresh mechanisms are also needed to ensure the value of current expertise, such as actuaries’ capacity to model commercial and household risk for insurance purposes. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/water-may-soon-lap-at-the-door-but-still-some-homeowners-dont-want-to-rock-the-boat-124289">Water may soon lap at the door, but still some homeowners don't want to rock the boat</a>
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<p>Greater use of cross-disciplinary collaboration will be needed too — for example, in building design and construction.</p>
<h2>How 6 disciplines are responding</h2>
<p>Engineering is synonymous with industrial society so has much to reflect on in terms of repurposing. Engineers will have to recalibrate their earlier assumptions. As UWA environmental engineer <a href="https://theconversation.com/profiles/anas-ghadouani-729335">Anas Ghadouani</a> notes:</p>
<blockquote>
<p>Consider the fact that the sectors at the top of the emissions pyramid, including transport, electricity production and manufacturing, contributed over 75% of emissions. These top emitting sectors have been flush with engineers and engineering companies.</p>
</blockquote>
<p>For architects to be credible in this new environment, they must grasp that “our modern experience of globalisation is predicated on three phenomena with spatial and environmental consequences: mobility, dispersion and density”, says UWA’s School of Design dean, <a href="https://www.uwa.edu.au/profile/kate-hislop">Kate Hislop</a>. Thus:</p>
<blockquote>
<p>Lowering CO₂ emissions involves regenerative design, adaptive reuse, life-cycle costing, carbon modelling, post-occupancy evaluation, waste minimisation and adoption of low embodied carbon materials and systems.</p>
</blockquote>
<p>Academic law is heavily exposed, and its challenges, reports <a href="https://theconversation.com/profiles/david-hodgkinson-6574">David Hodgkinson</a> from UWA’s School of Law, boil down to the laws and regulations that can be introduced to reduce emissions and assist people, species and ecosystems vulnerable to climate change. It is a question of intergenerational justice. He concludes: </p>
<blockquote>
<p>The main issue at stake is that if we agree to reduce emissions now, people living in the future will benefit, not those living today. But we will, today, bear the costs of reducing such emissions.</p>
</blockquote>
<p>For economists, whose counsel has become embedded in part thanks to the landmark <a href="https://www.lse.ac.uk/granthaminstitute/publication/the-economics-of-climate-change-the-stern-review/">Stern Report</a>, the greatest contribution has been in evaluating policy options that could reduce greenhouse gas emissions. Their very strong consensus is that the key policy response is to place a price on greenhouse gas emissions. <a href="https://theconversation.com/profiles/david-pannell-223">David Pannell</a>, who leads UWA’s Centre for Environmental Economics and Policy, states: </p>
<blockquote>
<p>There are differences of opinion about whether a tax or a market in permits would be superior [in reducing emissions], but there is almost no dissent among economists that one or the other of these is needed.</p>
</blockquote>
<p>In the field of health care, the emphasis is on training health-care professionals. For <a href="https://research-repository.uwa.edu.au/en/persons/sajni-gudka">Sajni Gudka</a>, from UWA’s School of Population and Global Health, climate change amounts to a public health emergency:</p>
<blockquote>
<p>Real capacity shortfalls are close by in responding to growing infectious diseases, heat stress, food insecurity, poor water quality and nutrition.</p>
</blockquote>
<p>Finally, for oceanography the urgency lies in mitigating the effects of climate change in coastal zones. <a href="https://research-repository.uwa.edu.au/en/persons/julian-partridge">Julian Partridge</a> and <a href="https://theconversation.com/profiles/charitha-pattiaratchi-110101">Charitha Pattiaratchi</a>, of UWA’s Oceans Institute, say a breakthrough depends on a grand alliance of disciplinary perspectives:</p>
<blockquote>
<p>Climate change challenges cannot be solved by engineers and scientists alone. They need alliances with social scientists, cultural heritage specialists and others to join this collective endeavour.</p>
</blockquote>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/this-is-how-universities-can-lead-climate-action-147191">This is how universities can lead climate action</a>
</strong>
</em>
</p>
<hr>
<h2>Waiting for political action</h2>
<p>The focus of the report is on the academic sector, related professions and the knowledge economy. But the preparedness question is also being asked of the political class and specific governments. As public attitudes become accustomed to environmental stewardship, heightened by the <a href="https://theconversation.com/humans-see-just-4-7km-into-the-distance-so-how-can-we-truly-understand-what-the-bushfires-destroyed-128539">bushfire crisis</a> last summer, voters are beginning to choose a direction of travel that was until recently dismissed.</p>
<p>In Western Australia, the government has just released its new <a href="https://www.wa.gov.au/service/environment/environment-information-services/western-australian-climate-change-policy">Climate Change Policy</a>, following several other states. <a href="https://www.dea.org.au/climate-change/">Doctors for the Environment Australia</a> is one of many campaigns that question the sagacity of short-term economic priorities.</p>
<p>How prepared is the country’s political class to use the advances made by universities and professions to address climate change?</p><img src="https://counter.theconversation.com/content/151662/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Shamit Saggar does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Universities and the professions are changing in response to climate change. When will the advances in knowledge and practice we are already seeing prompt governments to act with the required urgency?Shamit Saggar, Professor and Director, Public Policy institute, The University of Western AustraliaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1368042020-04-28T13:34:40Z2020-04-28T13:34:40ZSeabed fossils show the ocean is undergoing a change not seen for 10,000 years<figure><img src="https://images.theconversation.com/files/331029/original/file-20200428-110734-1kx1lcn.jpg?ixlib=rb-1.1.0&rect=5%2C5%2C3827%2C2545&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Oskari Porkka / shutterstock</span></span></figcaption></figure><p>Changes in ocean circulation may have caused a shift in Atlantic Ocean ecosystems not seen for the past 10,000 years, new analysis of deep-sea fossils has revealed.</p>
<p>This is the striking finding of a new study led by a research group I am part of at UCL, funded by the <a href="https://www.eu-atlas.org/">ATLAS</a> project and published in the journal <a href="https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2020GL087577">Geophysical Research Letters</a>. The shift has likely already led to political tensions as fish migrate to colder waters.</p>
<p>The climate has been quite stable over the 12,000 years or so since the end of the last Ice Age, a period known as the Holocene. It is thought that this stability is what allowed <a href="https://theconversation.com/climate-and-the-rise-and-fall-of-civilizations-a-lesson-from-the-past-51907">human civilisation</a> to really get going. </p>
<p>In the ocean, the major currents are also thought to have been relatively stable during the Holocene. These currents have natural cycles, which affect where marine organisms can be found, including plankton, fish, seabirds and whales.</p>
<p>Yet climate change in the ocean is becoming apparent. Tropical coral reefs are <a href="https://www.theguardian.com/environment/2020/apr/08/snow-white-coral-of-once-vibrant-great-barrier-reef-a-sign-urgent-action-must-be-taken">bleaching</a>, the oceans becoming more acidic as they absorb carbon from the atmosphere, and species like herring or mackerel are <a href="https://www.scientificamerican.com/article/ocean-species-are-shifting-toward-the-poles/">moving towards the poles</a>. But there still seems to be a prevailing view that not much has happened in the ocean so far – in our minds the really big impacts are confined to the future.</p>
<h2>Looking into the past</h2>
<p>To challenge this point of view, we had to look for places where seabed fossils not only covered the industrial era in detail, but also stretched back many thousands of years. And we found the right patch of seabed just south of Iceland, where a major deep sea current causes sediment to pile up in huge quantities. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/331031/original/file-20200428-110752-fc3ln0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/331031/original/file-20200428-110752-fc3ln0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/331031/original/file-20200428-110752-fc3ln0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=552&fit=crop&dpr=1 600w, https://images.theconversation.com/files/331031/original/file-20200428-110752-fc3ln0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=552&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/331031/original/file-20200428-110752-fc3ln0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=552&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/331031/original/file-20200428-110752-fc3ln0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=693&fit=crop&dpr=1 754w, https://images.theconversation.com/files/331031/original/file-20200428-110752-fc3ln0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=693&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/331031/original/file-20200428-110752-fc3ln0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=693&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Scientists gathered fossils from an area with lots of seabed sediment.</span>
<span class="attribution"><span class="source">Peter Spooner</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>To get our fossil samples we took cores of the sediment, which involves sending long plastic tubes to the bottom of the ocean and pushing them into the mud. When pulled out again, we were left with a tube full of sediment that can be washed and sieved to find fossils. The deepest sediment contains the oldest fossils, while the surface sediment contains fossils that were deposited within the past few years. </p>
<p>One of the simplest ways of working out what the ocean was like in the past is to count the different species of tiny fossil plankton that can be found in such sediments. Different species like to live in different conditions. We looked at a type called foraminifera, which have shells of calcium carbonate. Identifying them is easy to do using a microscope and small paintbrush, which we use when handling the fossils so they don’t get crushed.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/331032/original/file-20200428-110765-1xfr6xr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/331032/original/file-20200428-110765-1xfr6xr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/331032/original/file-20200428-110765-1xfr6xr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/331032/original/file-20200428-110765-1xfr6xr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/331032/original/file-20200428-110765-1xfr6xr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/331032/original/file-20200428-110765-1xfr6xr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/331032/original/file-20200428-110765-1xfr6xr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/331032/original/file-20200428-110765-1xfr6xr.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">Electron microscope image of the tiny fossil plankton <em>G. bulloides</em>, a type of foraminifera found during the study.</span>
<span class="attribution"><span class="source">Alessio Fabbrini, UCL</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>A <a href="https://www.smithsonianmag.com/science-nature/plankton-havent-been-same-industrial-revolution-180972266/">recent global study</a> showed that modern foraminifera distributions are different to the start of the industrial era. Climate change is clearly already having an impact.</p>
<p>Similarly, the view that modern ocean currents are like those of the past couple of thousand years was challenged by <a href="https://theconversation.com/climate-change-is-slowing-atlantic-currents-that-help-keep-europe-warm-94930">our work in 2018</a>, which showed that the overturning “conveyor belt” circulation was at its weakest for 1,500 years. Our new work builds on this picture and suggests that modern North Atlantic surface circulation is different to anything seen in the past 10,000 years – almost the whole Holocene.</p>
<p>The effects of the unusual circulation can be found across the North Atlantic. Just south of Iceland, a reduction in the numbers of cold-water plankton species and an increase in the numbers of warm-water species shows that warm waters have replaced cold, nutrient-rich waters. We believe that these changes have also led to a northward movement of key fish species such as mackerel, which is already causing <a href="https://www.nytimes.com/2019/11/29/climate/climate-change-ocean-fish-iceland.html">political headaches</a> as different nations vie for fishing rights. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/331037/original/file-20200428-110785-1xi0yuh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/331037/original/file-20200428-110785-1xi0yuh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/331037/original/file-20200428-110785-1xi0yuh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=900&fit=crop&dpr=1 600w, https://images.theconversation.com/files/331037/original/file-20200428-110785-1xi0yuh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=900&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/331037/original/file-20200428-110785-1xi0yuh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=900&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/331037/original/file-20200428-110785-1xi0yuh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1131&fit=crop&dpr=1 754w, https://images.theconversation.com/files/331037/original/file-20200428-110785-1xi0yuh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1131&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/331037/original/file-20200428-110785-1xi0yuh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1131&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Members of the team collect ocean sediment.</span>
<span class="attribution"><span class="source">Ian Hall, Cardiff University</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Further north, other fossil evidence shows that more warm water has been reaching the Arctic from the Atlantic, likely contributing to melting sea ice. Further west, a slowdown in the <a href="https://theconversation.com/climate-change-is-slowing-atlantic-currents-that-help-keep-europe-warm-94930">Atlantic conveyor circulation</a> means that waters are not warming as much as we would expect, while furthest west close to the US and Canada the warm gulf stream seems to be shifting northwards which will have <a href="https://www.whoi.edu/press-room/news-release/feeling-the-heat-in-the-nw-atlantic/">profound consequences</a> for important fisheries.</p>
<p>One of the ways that these circulation systems can be affected is when the North Atlantic gets less salty. Climate change can cause this to happen by increasing rainfall, increasing ice melt, and increasing the amount of water coming out of the Arctic Ocean. Melting following the peak of the Little Ice Age in the mid 1700s may have triggered an input of freshwater, causing some of the earliest changes that we found, with modern climate change helping to propel those changes beyond the natural variability of the Holocene.</p>
<p>We still don’t know what has ultimately caused these changes in ocean circulation. But it does seem that the ocean is more sensitive to modern climate changes than previously thought, and we will have to adapt.</p><img src="https://counter.theconversation.com/content/136804/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Peter T. Spooner receives funding from Europe's Horizon 2020 ATLAS project, the National Environment Research Council (UK), and the Leverhulme Trust. The work was also part funded by the National Science Foundation (USA). He is affiliated with the Green Party (UK). </span></em></p>Cold-water plankton is being replaced by warm-water species.Peter T. Spooner, Teaching Fellow in Earth Sciences, UCLLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1326882020-03-02T16:16:53Z2020-03-02T16:16:53ZHalf of world’s sandy beaches could disappear due to sea level rise by 2100<figure><img src="https://images.theconversation.com/files/318022/original/file-20200302-18308-w8cexq.jpg?ixlib=rb-1.1.0&rect=0%2C233%2C3985%2C2300&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A crowded Copacabana Beach in Rio de Janeiro, Brazil.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/rio-de-janeiro-brazil-aerial-view-1293099220">R.M. Nunes/Shutterstock</a></span></figcaption></figure><p>Up to half of the world’s sandy beaches are at risk of disappearing by the end of this century if no action is taken to limit greenhouse gas emissions. That’s according to <a href="https://nature.com/articles/s41558-020-0697-0">a new study, published in Nature Climate Change</a>. Even assuming a better outcome for action on climate change, where global emissions peak around 2040, well over one-third (37%) of the world’s beaches would be lost by 2100.</p>
<p>Researchers had previously analysed satellite images showing shoreline change from 1984 to 2016. They found that a quarter of sandy beaches worldwide had already <a href="https://www.nature.com/articles/s41598-018-24630-6">eroded at a rate of more than 0.5m per year</a>, shedding over <a href="https://www.nature.com/articles/s41598-018-30904-w">28,000 square kilometres of land</a> to the sea.</p>
<p>The rate at which sea levels are rising is accelerating by <a href="https://www.pnas.org/content/115/9/2022.short">about 0.1mm per year each year</a>. But sea level rise won’t be even across the globe. The term “sea level” can be misleading – the sea surface is not flat. Much like the atmosphere, it has high and low pressure areas which create mounds and troughs. Some of these are created by major currents, so changes that will take place as the oceans warm will change the topography of the sea surface. Some areas will receive less than the predicted average sea level rise, but many will see more.</p>
<p>More than 60% of sandy beaches in Gambia and Guinea-Bissau may be lost to erosion by rising seas, while Australia is expected to lose nearly 12,000 km of sandy coastline. For small island states such as Kiribati, the Marshall Islands and Tuvalu, losing 300m of land – as predicted for some – would be catastrophic.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/318059/original/file-20200302-18295-1sxqkml.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/318059/original/file-20200302-18295-1sxqkml.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/318059/original/file-20200302-18295-1sxqkml.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/318059/original/file-20200302-18295-1sxqkml.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/318059/original/file-20200302-18295-1sxqkml.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/318059/original/file-20200302-18295-1sxqkml.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/318059/original/file-20200302-18295-1sxqkml.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">An aerial view of Funafuti atoll, Tuvalu, shows the airstrip of Vaiaku international airport. There is little space for the coast to retreat as sea levels rise.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/tuvalu-under-wing-airplane-aerial-view-1221046468">Maloff/Shutterstock</a></span>
</figcaption>
</figure>
<h2>Nowhere to go</h2>
<p>Sandy beaches occupy more than one-third of the global coastline and of all the different types of beaches, sandy beaches are the most heavily used by people. Many coastal areas have been built on, for industry, housing and tourist resorts. </p>
<p>These “softer” parts of the shoreline have always been at the mercy of ocean storms and the tides. But the predicted sea level rise on top of these daily inundations pushes the boundary between coast and sea inland, a process known as coastal retreat. </p>
<p>The build-up of people and concrete at the landward fringe of sandy beaches has created an abrupt barrier to coastal retreat, preventing beaches from moving inland as sea levels rise. Instead, sandy stretches of coastline are at risk of being eroded and washed away entirely.</p>
<p>Warming seas also promise more intense and frequent storms, which are capable of moving entire beaches overnight. Porthleven Beach in Cornwall, UK <a href="https://theconversation.com/why-beaches-lose-their-sand-and-then-suddenly-reappear-77503">lost all of its sand</a> during a storm in January 2015, to be returned by the tide a few days later.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"563449499339591681"}"></div></p>
<p>Soft sandy beaches are continuously moved by waves and currents – depleting them in certain areas and depositing them in others. This transport of sand is normal, but the combined force of higher sea levels and stronger storms could spell extinction for many beaches.</p>
<p>All of this is very worrying for the millions of people who call these regions home. The world’s sandy coastlines tend to be densely populated, and are <a href="https://journals.plos.org/plosone/article%3Fid%3D10.1371/journal.pone.0118571">becoming more so</a> over time. In <a href="https://www.sciencedirect.com/science/article/pii/S0921818113002026?via%3Dihub">other research</a>, it was found that sea level rise by 0.8m could erase 17,000 square km of land and force up to 5.3 million people to migrate, with an associated cost of USD$300-1,000 billion globally. In <a href="https://link.springer.com/article/10.1007%2Fs10113-011-0249-2">Africa alone</a>, up to 40,000 people per year could be forced to migrate due to land loss by coastal erosion if no adaptive measures are in place by 2100.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/climate-change-sea-level-rise-could-displace-millions-of-people-within-two-generations-116753">Climate change: sea level rise could displace millions of people within two generations</a>
</strong>
</em>
</p>
<hr>
<p>But it isn’t just climate change. Humans are actively accelerating coastal erosion by removing sand from beaches in enormous quantities and at much faster rates than it can be naturally renewed. Gravel and sand is extracted from rivers and on beaches for use in construction – and at a faster rate than fossil fuel extraction in some areas. </p>
<p>Coastal ecosystems that bind and trap sediment, like mangrove swamps, are also being destroyed. The world <a href="https://www.iucn.org/sites/dev/files/content/documents/mangroveloss-brief-4pp-19.10.low_.pdf">lost almost 10,000 square kilometres</a> of these habitats between 1996 and 2016. Meanwhile, sediment supply to the coast is also affected by building dams and irrigation systems upstream.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/318064/original/file-20200302-18279-17jg971.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/318064/original/file-20200302-18279-17jg971.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/318064/original/file-20200302-18279-17jg971.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/318064/original/file-20200302-18279-17jg971.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/318064/original/file-20200302-18279-17jg971.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/318064/original/file-20200302-18279-17jg971.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/318064/original/file-20200302-18279-17jg971.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">Mangroves are effective buffers against storms and help trap more sand around the coast.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/tanaman-bakau-shrub-small-tree-that-1541915537">Ibenk_88/Shutterstock</a></span>
</figcaption>
</figure>
<p>Sea level rise is inevitable, but <a href="https://theconversation.com/sea-level-rise-is-inevitable-but-what-we-do-today-can-still-prevent-catastrophe-for-coastal-regions-124129">how bad it will be is still not certain</a>. Replenishing the most endangered beaches by pumping sand onto them – a process called “coastal nourishment” – <a href="https://www.sciencedirect.com/science/article/pii/S0921818113002026?via%3Dihub">could cost USD$65–220 billion in total</a>, but that’s still less than one-fifth of the economic cost of taking no action at all on sea level rise. It could reduce land loss by up to 14%, lower the number of people that might be forced to migrate by up to 68%, and shrink the cost of forced migration by up to 85% by 2100. </p>
<p>Even “<a href="https://nature.com/articles/s41558-020-0697-0">moderate emission mitigation policy</a>”, as the new study calls it, in which global emissions peak around 2040, could prevent 40% of the landward retreat of shorelines by 2100. On average, this would save more than 40m width of sandy beach around the world, from an average loss of around 250m.</p>
<p>Coastal nourishment can have its own ecological problems, so it would have to be done with careful attention to the local environment. But much of what needs to be done to save the world’s sandy beaches lies within our grasp already – if we can just reduce the rate at which we’re consuming sand and burning fossil fuels. By doing that – and expanding and protecting coastal habitats – the terrible predictions from this new research might never come to pass.</p>
<hr>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=140&fit=crop&dpr=1 600w, https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=140&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=140&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=176&fit=crop&dpr=1 754w, https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=176&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=176&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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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=Imagineheader1132688">Click here to subscribe to our climate action newsletter. Climate change is inevitable. Our response to it isn’t.</a></em></p><img src="https://counter.theconversation.com/content/132688/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Simon Boxall receives funding from NERC and the EU. </span></em></p><p class="fine-print"><em><span>Abiy S. Kebede does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Sandy beaches are densely populated and occupy more than one third of the global coastline.Simon Boxall, Senior Lecturer in Ocean and Earth Science, University of SouthamptonAbiy S. Kebede, Lecturer in Flood and Coastal Engineering, Brunel University LondonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1211682019-10-07T12:39:56Z2019-10-07T12:39:56ZHow deep is the ocean?<figure><img src="https://images.theconversation.com/files/295668/original/file-20191004-118252-14jpb8t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The remotely operated vehicle Deep Discoverer captures images of a newly discovered hydrothermal vent field in the western Pacific.</span> <span class="attribution"><a class="source" href="https://oceanexplorer.noaa.gov/okeanos/explorations/ex1605/logs/photolog/welcome.html#cbpi=/okeanos/explorations/ex1605/dailyupdates/media/june24.html">NOAA</a></span></figcaption></figure><figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=293&fit=crop&dpr=1 600w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=293&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=293&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=368&fit=crop&dpr=1 754w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=368&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=368&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p><em><a href="https://theconversation.com/us/topics/curious-kids-us-74795">Curious Kids</a> is a series for children of all ages. If you have a question you’d like an expert to answer, send it to <a href="mailto:curiouskidsus@theconversation.com">curiouskidsus@theconversation.com</a>.</em></p>
<hr>
<blockquote>
<p><strong>How deep is the ocean?</strong></p>
</blockquote>
<hr>
<p>Explorers started making navigation charts showing how wide the ocean was more than 500 years ago. But it’s much harder to calculate how deep it is. </p>
<p>If you wanted to measure the depth of a pool or lake, you could tie a weight to a string, lower it to the bottom, then pull it up and measure the wet part of the string. In the ocean you would need a rope thousands of feet long. </p>
<p>In 1872 the <a href="https://divediscover.whoi.edu/history-of-oceanography/the-challenger-expedition/">HMS Challenger</a>, a British Navy ship, set sail to learn about the ocean, including its depth. It carried 181 miles (291 kilometers) of rope.</p>
<p>During their four-year voyage, the Challenger crew collected samples of rocks, mud and animals from many different areas of the ocean. They also found one of the deepest zones, in the western Pacific, <a href="https://www.livescience.com/23387-mariana-trench.html">the Mariana Trench</a> which stretches for 1,580 miles (2,540 kilometers).</p>
<p>Today scientists know that on average the ocean is 2.3 miles (3.7 kilometers) deep, but many parts are much shallower or deeper. To measure depth they use sonar, which stands for Sound Navigation And Ranging. A ship sends out pulses of sound energy and measures depth based on how quickly the sound travels back. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/8ijaPa-9MDs?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Survey ships use multibeam sonar to measure the depth of the sea floor.</span></figcaption>
</figure>
<p>The deepest parts of the ocean are trenches – long, narrow depressions, like a trench in the ground, but much bigger. The HMS Challenger sampled one of these zones at the southern end of the Mariana Trench, which might be the deepest point in the ocean. Known as the Challenger Deep, it is 35,768 to 36,037 feet deep – almost 7 miles (11 kilometers).</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/UwVNkfCov1k?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">In the ocean’s deepest zones, many life forms have adapted to live in the dark under crushing water pressure.</span></figcaption>
</figure>
<p><a href="https://scholar.google.com/citations?user=ruUF3z4AAAAJ&hl=en">Ocean scientists like me</a> study the sea floor because it helps us understand how Earth functions. For example, our planet’s outer layer is made of tectonic plates – huge moving slabs of rock and sediment. The Hawaiian-Emperor Seamount chain, a line of peaks on the ocean floor, was created when a tectonic plate moved over a spot where hot rock welled up from deep inside the Earth.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/295654/original/file-20191004-118228-gjgaf1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/295654/original/file-20191004-118228-gjgaf1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/295654/original/file-20191004-118228-gjgaf1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=474&fit=crop&dpr=1 600w, https://images.theconversation.com/files/295654/original/file-20191004-118228-gjgaf1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=474&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/295654/original/file-20191004-118228-gjgaf1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=474&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/295654/original/file-20191004-118228-gjgaf1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=595&fit=crop&dpr=1 754w, https://images.theconversation.com/files/295654/original/file-20191004-118228-gjgaf1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=595&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/295654/original/file-20191004-118228-gjgaf1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=595&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 Emperor Seamounts are a trail of underwater mountains in the Pacific, created when a tectonic plate moved across the Hawaii hotspot over millions of years.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Hawaiian%E2%80%93Emperor_seamount_chain#/media/File:Hawaii_hotspot.jpg">NOAA</a></span>
</figcaption>
</figure>
<p>When two tectonic plates move away from each other underwater, new material rises up into Earth’s crust. This process, which creates new ocean floor, is called <a href="https://www.nationalgeographic.org/encyclopedia/seafloor-spreading/">seafloor spreading</a>. Sometimes super-hot fluids from inside the Earth shoot up through cracks in the ocean floor called <a href="https://www.whoi.edu/feature/history-hydrothermal-vents/discovery/1979-2.html">hydrothermal vents</a>.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/295659/original/file-20191004-118239-eqehz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/295659/original/file-20191004-118239-eqehz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/295659/original/file-20191004-118239-eqehz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=307&fit=crop&dpr=1 600w, https://images.theconversation.com/files/295659/original/file-20191004-118239-eqehz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=307&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/295659/original/file-20191004-118239-eqehz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=307&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/295659/original/file-20191004-118239-eqehz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=386&fit=crop&dpr=1 754w, https://images.theconversation.com/files/295659/original/file-20191004-118239-eqehz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=386&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/295659/original/file-20191004-118239-eqehz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=386&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Spreading at a mid-ocean ridge.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Seafloor_spreading#/media/File:Ridge_render.jpg">NASA</a></span>
</figcaption>
</figure>
<p>Amazing fish, shellfish, tube worms and other life forms live in these zones. Between the creation and destruction of ocean plates, sediments collect on the sea floor and provide an <a href="https://theconversation.com/scientists-have-been-drilling-into-the-ocean-floor-for-50-years-heres-what-theyve-found-so-far-100309">archive of Earth’s history</a>, the evolution of climate and life that is available nowhere else.</p>
<hr>
<p><em>Hello, curious kids! Do you have a question you’d like an expert to answer? Ask an adult to send your question to <a href="mailto:curiouskidsus@theconversation.com">curiouskidsus@theconversation.com</a>.</em>
<em>Please tell us your name, age and the city where you live. We won’t be able to answer every question, but we will do our best.</em></p><img src="https://counter.theconversation.com/content/121168/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Suzanne OConnell 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>In some places, the ocean is almost 7 miles deep. Scientists exploring the ocean floor have found strange sea creatures, bizarre geologic formations and records of Earth’s history.Suzanne OConnell, Professor of Earth and Environmental Sciences, Wesleyan UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1124012019-04-04T04:00:13Z2019-04-04T04:00:13ZHow Leonardo da Vinci, ‘Master of Water’, explored the power and beauty of its flow<figure><img src="https://images.theconversation.com/files/261146/original/file-20190227-150705-5bh2g7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Old man (possible self-portrait) and water studies, c 1508-9.</span> <span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Old_Man_with_Water_Studies.jpg">Wikimedia Commons</a></span></figcaption></figure><p><em>On the 500th anniversary of his death, our series Leonardo da Vinci Revisited brings together scholars from different disciplines to re-examine his work, legacy and myth.</em></p>
<p>The artist and polymath Leonardo da Vinci was once famously named a “Master of Water” in the records of the Florentine government. </p>
<p>In this role, he explored diverting the river Arno away from Pisa so as to cut access to the city, then Florence’s enemy, from the sea. It was one of a number of jobs he held that were dedicated to controlling water as a way of wielding power.</p>
<p>But his notebooks reveal Leonardo’s wider preoccupations with the power of water. He wanted to understand the ebb and flow of tides, the origins of rivers and oceans and the water cycle, as well as the fearsome effects of water in erosion, floods, rain and storms. Water was a force to be reckoned with — as an idea and as a reality.</p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/261158/original/file-20190227-150708-35wcjt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/261158/original/file-20190227-150708-35wcjt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/261158/original/file-20190227-150708-35wcjt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=408&fit=crop&dpr=1 600w, https://images.theconversation.com/files/261158/original/file-20190227-150708-35wcjt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=408&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/261158/original/file-20190227-150708-35wcjt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=408&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/261158/original/file-20190227-150708-35wcjt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=513&fit=crop&dpr=1 754w, https://images.theconversation.com/files/261158/original/file-20190227-150708-35wcjt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=513&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/261158/original/file-20190227-150708-35wcjt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=513&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Model of hydraulic saw, a reconstruction of Leonardo’s design, in Milan’s National Museum of Science and Technology, 2011.</span>
<span class="attribution"><span class="source">Jakub Hałun via Wikimedia Commons</span></span>
</figcaption>
</figure>
<p>If humans could not control water, Leonardo argued, they could nonetheless work with it. Over his lifetime, he was commissioned for a range of projects to manipulate water, most often in canals, as a form of warfare.</p>
<p>When Leonardo wrote down his thoughts about how to depict a biblical deluge, central to his thinking was the destructive force of water: “The swollen waters will sweep round the pool which contains them striking in eddying whirlpools against the different obstacles, and leaping into the air in muddy foam; then, falling back, the beaten water will again be dashed into the air.”</p>
<p>His mindset was biblical but he shared with modern scientists an interest in great destructive forces such as tsunamis.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/261147/original/file-20190227-150721-18vfz44.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/261147/original/file-20190227-150721-18vfz44.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/261147/original/file-20190227-150721-18vfz44.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=474&fit=crop&dpr=1 600w, https://images.theconversation.com/files/261147/original/file-20190227-150721-18vfz44.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=474&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/261147/original/file-20190227-150721-18vfz44.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=474&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/261147/original/file-20190227-150721-18vfz44.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=596&fit=crop&dpr=1 754w, https://images.theconversation.com/files/261147/original/file-20190227-150721-18vfz44.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=596&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/261147/original/file-20190227-150721-18vfz44.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=596&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 deluge, c.1517–18, Pen and black ink with wash on paper, RCIN 912380 via Google Art Project.</span>
<span class="attribution"><span class="source">Wikimedia Commons</span></span>
</figcaption>
</figure>
<h2>The beauty of water</h2>
<p>For Leonardo, water could also be exquisitely beautiful in its flows, eddies and swirls. His illustrations of moving water were not really observations of a single moment in time though; they captured his thought process. </p>
<p>In the illustration below, of water passing obstacles, he depicted movement in time and space, as well as his conceptualisation of how fluids flow, in a single diagram.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/261150/original/file-20190227-150712-x8uw1b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/261150/original/file-20190227-150712-x8uw1b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/261150/original/file-20190227-150712-x8uw1b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=865&fit=crop&dpr=1 600w, https://images.theconversation.com/files/261150/original/file-20190227-150712-x8uw1b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=865&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/261150/original/file-20190227-150712-x8uw1b.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=865&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/261150/original/file-20190227-150712-x8uw1b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1087&fit=crop&dpr=1 754w, https://images.theconversation.com/files/261150/original/file-20190227-150712-x8uw1b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1087&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/261150/original/file-20190227-150712-x8uw1b.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1087&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Studies of water passing obstacles and falling, c. 1508-9.</span>
<span class="attribution"><span class="source">Wikimedia Commons</span></span>
</figcaption>
</figure>
<p>Leonardo was depicting the inherently three-dimensional nature of flowing water, and the idea that turbulent flows consist of a range of co-existing eddies, varying in scale from large to small. This concept was mathematically formalised in 1941 by A.N. Kolmogorov, and is known as the “cascade model of turbulence”.</p>
<p>Visualisation of flowing water remains a powerful and essential tool in modern research today. For instance, recent laboratory studies of the <a href="https://doi.org/10.1007/s10652-019-09661-5">three-dimensional flow around islands in coastal ocean regions</a>, have used tiny plastic spheres to observe the fluid motion (known as particle tracking) of the evolving wake downstream of an island.</p>
<p>Describing the complex nature of these wakes, and the vertical up-welling of water in them, is key to understanding how the ecological productivity of these marine systems is maintained.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/263094/original/file-20190311-86717-1phleif.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/263094/original/file-20190311-86717-1phleif.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/263094/original/file-20190311-86717-1phleif.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=426&fit=crop&dpr=1 600w, https://images.theconversation.com/files/263094/original/file-20190311-86717-1phleif.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=426&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/263094/original/file-20190311-86717-1phleif.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=426&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/263094/original/file-20190311-86717-1phleif.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=535&fit=crop&dpr=1 754w, https://images.theconversation.com/files/263094/original/file-20190311-86717-1phleif.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=535&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/263094/original/file-20190311-86717-1phleif.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=535&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Paul M. Branson et al, Visualisation of the instantaneous flow field in the ‘unsteady bubble’ wake at 𝑡/𝑇=4.2; Streamlines seeded close to the bed and coloured by elevation.</span>
<span class="attribution"><span class="source">Environmental Fluid Mechanics journal. DOI /10.1007/s10652-019-09661-5</span></span>
</figcaption>
</figure>
<p>For Leonardo, flowing water formed parallels with curling hair: </p>
<blockquote>
<p>Observe the motion of the surface of the water which resembles that of hair, and has two motions, of which one goes on with the flow of the surface, the other forms the lines of the eddies; thus the water forms eddying whirlpools one part of which are due to the impetus of the principal current and the other to the incidental motion and return flow.</p>
</blockquote>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/261151/original/file-20190227-150694-1qzzygb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/261151/original/file-20190227-150694-1qzzygb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/261151/original/file-20190227-150694-1qzzygb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=573&fit=crop&dpr=1 600w, https://images.theconversation.com/files/261151/original/file-20190227-150694-1qzzygb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=573&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/261151/original/file-20190227-150694-1qzzygb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=573&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/261151/original/file-20190227-150694-1qzzygb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=720&fit=crop&dpr=1 754w, https://images.theconversation.com/files/261151/original/file-20190227-150694-1qzzygb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=720&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/261151/original/file-20190227-150694-1qzzygb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=720&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Study for the Head of Leda.</span>
<span class="attribution"><span class="source">Wikimedia Commons</span></span>
</figcaption>
</figure>
<p>Recently, scientists who study fluid mechanics <a href="https://www.youtube.com/watch?v=Q8DEwt11E64">have employed innovative ways</a> to communicate the results of their experiments through creating a musical representation of the frequency content of the flow. These modern methods share with Leonardo a fascination with the beauty of flowing water.</p>
<p>He may once have held the title “Master of Water” but Leonardo realised that this was one element of the natural world over which he (like others) could only ever exercise limited control, except perhaps, in his art.</p><img src="https://counter.theconversation.com/content/112401/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Susan Broomhall receives funding from the Australian Research Council.</span></em></p><p class="fine-print"><em><span>Greg Ivey receives funding from the Australian Research Council. </span></em></p><p class="fine-print"><em><span>Nicole L. Jones receives funding from the Australian Research Council.</span></em></p>Leonardo’s obsession with water flowed through his technical work, his art and his scientific ideas.Susan Broomhall, Professor of History, The University of Western AustraliaGreg Ivey, Professor of geophysical fluid dynamicsNicole L. Jones, Associate Professor of Physical Oceanography , The University of Western AustraliaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1104152019-01-25T11:52:12Z2019-01-25T11:52:12ZUniversity scientists feel the pain of the government shutdown, too<figure><img src="https://images.theconversation.com/files/255472/original/file-20190124-196235-lnw4qb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Federal and university employees normally work side by side on many big science projects.</span> <span class="attribution"><span class="source">ITAE</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>I am very fortunate. My work involves research on topics of interest and importance (OK maybe I’m biased) related to the climate and <a href="https://theconversation.com/what-is-the-warm-blob-in-the-pacific-and-what-can-it-tell-us-about-our-future-climate-40140">oceanography of the North Pacific</a>, and the weather of the Pacific Northwest.</p>
<p>My primary office is at the Pacific Marine Environmental Laboratory of the National Oceanographic and Atmospheric Administration, in Seattle, Washington, in a lovely setting on the shore of Lake Washington. My coworkers are an interesting bunch of folks doing a variety of work ranging from the <a href="https://doi.org/10.1038/nature14577">chemical oceanography of deep-sea volcanoes</a> to the causes and effects of <a href="https://doi.org/10.1175/BAMS-D-16-0323.1">declining sea ice in the Arctic</a>. This research involves the design and fabrication of innovative instrumentation, with most of this activity carried out in the laboratories and test benches on site.</p>
<p>It’s usually a bustling place. But these days, it’s been distressingly quiet.</p>
<p>The reason, of course, is the <a href="https://theconversation.com/us/topics/us-government-shutdown-2018-48781">partial shutdown of the federal government</a>, which has resulted in the furlough of “non-essential” employees of NOAA, a branch of the Department of Commerce.</p>
<p>I’m actually an employee of the University of Washington, so in principle, I should not be affected by the shutdown. But that’s far from the case, and my situation is by no means isolated.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/255460/original/file-20190124-196238-1frjwan.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/255460/original/file-20190124-196238-1frjwan.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/255460/original/file-20190124-196238-1frjwan.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/255460/original/file-20190124-196238-1frjwan.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/255460/original/file-20190124-196238-1frjwan.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/255460/original/file-20190124-196238-1frjwan.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/255460/original/file-20190124-196238-1frjwan.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/255460/original/file-20190124-196238-1frjwan.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A UW research scientist works with two NOAA scientists on an instrument before heading out on a cruise to Mexico’s northern coast.</span>
<span class="attribution"><a class="source" href="http://www.washington.edu/news/2016/05/10/uw-part-of-noaa-led-cruise-to-study-west-coast-ocean-acidification/">Simone Alin/NOAA</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>The Joint Institute for the Study of the Atmosphere and Ocean (JISAO) at UW has about 115 employees – and 89 of them have a federal facility as their primary place of work. The JISAO contingent at the NOAA lab actually outnumbers the federal employees. And JISAO is just one of <a href="https://ci.noaa.gov">16 cooperative institutes at universities</a> in the U.S. through which academic and NOAA scientists collaborate.</p>
<p>As a principal investigator whose paycheck comes from the university, I’ve been more hampered than crippled by the shutdown. There remains a seemingly infinite amount of work that can be done: papers to read, current projects needing attention, proposals to prepare. Much of this kind of work can be done away from the office. And I must admit that I kind of enjoyed the first few days; if nothing else the phone hardly rings at the temporary office I’m using.</p>
<p>But now I am getting really peeved. I was counting on being able to make headway on a study of past cold-air outbreaks in the Pacific Northwest, and really need to use a web application maintained by NOAA’s Air Resources Laboratory. Some other research in my pipeline requires climate model data sets hosted by NOAA, but again, no dice.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/255470/original/file-20190124-196218-q5dfx7.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/255470/original/file-20190124-196218-q5dfx7.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/255470/original/file-20190124-196218-q5dfx7.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=330&fit=crop&dpr=1 600w, https://images.theconversation.com/files/255470/original/file-20190124-196218-q5dfx7.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=330&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/255470/original/file-20190124-196218-q5dfx7.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=330&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/255470/original/file-20190124-196218-q5dfx7.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=415&fit=crop&dpr=1 754w, https://images.theconversation.com/files/255470/original/file-20190124-196218-q5dfx7.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=415&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/255470/original/file-20190124-196218-q5dfx7.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"></a>
<figcaption>
<span class="caption">Screenshot of what greets visitors to many NOAA websites during the shutdown.</span>
<span class="attribution"><a class="source" href="https://government-shutdown.noaa.gov">NOAA</a></span>
</figcaption>
</figure>
<p>One might suppose that a slowing of the research being conducted in my field is no big deal. But there are ramifications. </p>
<p>Take weather forecasting. Both day-to-day forecasts and seasonal projections rely on complex computer models. These models need care and feeding; there is continual development and improvement carried out by a cadre of federal and nonfederal (academic and contractor) types. All of this is basically on hold. To be sure, forecasts are still being produced by National Weather Service personnel temporarily working for free, but it is a setback. And this kind of pause is happening all over the country, in a variety of disciplines, at research centers that collaborate with federal agencies – when the government isn’t shut down.</p>
<p>The work not being done will have some lasting effects. For example, a research cruise in the Atlantic Ocean scheduled to begin in about a month was going to include instrumentation for measuring various chemical properties including pH. Now it looks like equipment will not be able to be prepped and shipped in time. This will constitute a serious gap in the record.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/255471/original/file-20190124-196215-1y1ej5o.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/255471/original/file-20190124-196215-1y1ej5o.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/255471/original/file-20190124-196215-1y1ej5o.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=189&fit=crop&dpr=1 600w, https://images.theconversation.com/files/255471/original/file-20190124-196215-1y1ej5o.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=189&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/255471/original/file-20190124-196215-1y1ej5o.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=189&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/255471/original/file-20190124-196215-1y1ej5o.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=237&fit=crop&dpr=1 754w, https://images.theconversation.com/files/255471/original/file-20190124-196215-1y1ej5o.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=237&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/255471/original/file-20190124-196215-1y1ej5o.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=237&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Ongoing monitoring – like this time series of temperatures on the Bering Sea shelf – is necessary to track accurately how environmental conditions are changing.</span>
<span class="attribution"><span class="source">Phyllis Stabeno/NOAA</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>It bears emphasizing that there are a variety of roles filled by JISAO personnel at NOAA, and the extent to which these individuals can roll with the punches associated with the shutdown also varies. </p>
<p>Support scientists employed by the university are in a particularly tough spot. These are the people who carry out the essential tasks of preparing and calibrating equipment, going to sea on research cruises – a duty generally less glamorous than the term suggests – analyzing samples in the lab, and processing and posting the precious data that we go to so much trouble to collect. There is not much glory here, but these folks are committed to what they are doing and take justifiable pride in their work.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/255477/original/file-20190124-196244-3gncys.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/255477/original/file-20190124-196244-3gncys.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/255477/original/file-20190124-196244-3gncys.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=451&fit=crop&dpr=1 600w, https://images.theconversation.com/files/255477/original/file-20190124-196244-3gncys.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=451&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/255477/original/file-20190124-196244-3gncys.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=451&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/255477/original/file-20190124-196244-3gncys.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=567&fit=crop&dpr=1 754w, https://images.theconversation.com/files/255477/original/file-20190124-196244-3gncys.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=567&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/255477/original/file-20190124-196244-3gncys.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=567&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Workstations at NOAA/PMEL are now empty, even though many of the people who staff them are actually employed by the university.</span>
<span class="attribution"><span class="source">Jed Thompson/JISAO</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>As the shutdown has dragged on, and PMEL and other federal facilities remain closed, the options for these individuals have become increasingly limited. Those whose work directly involves equipment and instrumentation are especially in a bind. Many have been able to be productive by updating manuals or online training, but are running out of things to do. Those tasked with data processing and management often use specialized software on their desktop computers – this kind of work can’t be done on one’s laptop at the local Starbucks.</p>
<p>JISAO and federal employees work alongside one another, and the distinctions are usually blurred. In many cases, these folks have similar duties and tenures, and it’s not much more than a matter of chance whether one is a federal or nonfederal employee.</p>
<p>But now that distinction is important, because different rules are in play for the federal and nonfederal employees. Federal employees on furlough will be receiving back pay. This does not apply to JISAO employees, and for that matter, all their counterparts across the country associated with the different agencies being directly affected by the impasse.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/255474/original/file-20190124-196250-mil0hs.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/255474/original/file-20190124-196250-mil0hs.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/255474/original/file-20190124-196250-mil0hs.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/255474/original/file-20190124-196250-mil0hs.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/255474/original/file-20190124-196250-mil0hs.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/255474/original/file-20190124-196250-mil0hs.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/255474/original/file-20190124-196250-mil0hs.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/255474/original/file-20190124-196250-mil0hs.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">At a certain point during the shutdown, people run out of work to do.</span>
<span class="attribution"><span class="source">University of Washington</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>If JISAO employees cannot carry out meaningful work benefiting the grant projects they’re working under, they must either find a project to which they can contribute (which is difficult to say the least), take vacation time, or worst of all in most cases, go on leave without pay.</p>
<p>Some individuals have already been forced to use leave or go without pay, with poor prospects for reimbursement, and I fear that their ranks will swell. JISAO is doing what it can on behalf of its employees, as are the other NOAA cooperative institutes, especially toward minimizing the “nuclear option” of forced leave without pay. Given the requirements accompanying university employees working on federal grants, that is proving to be no cinch.</p>
<p>Here’s a fervent plea for an agreement to be reached somehow so that we can get back to our regular work. I am chomping at the bit, and I expect that I speak for a lot of people.</p><img src="https://counter.theconversation.com/content/110415/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Nicholas Bond 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>Lots of academic scientists collaborate with federal employees and resources on their research projects. And at the moment they can’t. A climatologist explains the bind they’re in.Nicholas Bond, Washington State Climatologist and Associate Professor of Atmospheric Sciences, University of WashingtonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1061642018-11-15T18:58:57Z2018-11-15T18:58:57ZExplainer: how the Antarctic Circumpolar Current helps keep Antarctica frozen<figure><img src="https://images.theconversation.com/files/245674/original/file-20181115-194516-mec002.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The Antarctic Circumpolar Current keeps Antarctica cold. </span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>The Antarctic Circumpolar Current, or ACC, is the strongest ocean current on our planet. It extends from the sea surface to the bottom of the ocean, and encircles Antarctica. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/245300/original/file-20181113-194500-1whkbdt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/245300/original/file-20181113-194500-1whkbdt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/245300/original/file-20181113-194500-1whkbdt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/245300/original/file-20181113-194500-1whkbdt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/245300/original/file-20181113-194500-1whkbdt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/245300/original/file-20181113-194500-1whkbdt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/245300/original/file-20181113-194500-1whkbdt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/245300/original/file-20181113-194500-1whkbdt.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>
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<span class="caption">Scientists deploying a vertical microstructure profiler (VMP-2000), which measures temperature, salinity, pressure and turbulence, from RV Investigator in the Antarctic Circumpolar Current, November 2018.</span>
<span class="attribution"><span class="source">Nathan Bindoff</span></span>
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<p>It is vital for Earth’s health because it keeps Antarctica cool and frozen. It is also changing as the world’s climate warms. Scientists like us are studying the current to find out how it might affect the future of Antarctica’s ice sheets, and the world’s sea levels. </p>
<p>The ACC carries an estimated <a href="https://doi.org/10.1002/2016GL070319">165 million to 182 million cubic metres of water every second</a> (a unit also called a “<a href="https://en.wikipedia.org/wiki/Sverdrup">Sverdrup</a>”) from west to east, more than 100 times the flow of all the rivers on Earth. It provides the main connection between the Indian, Pacific and Atlantic Oceans. </p>
<p>The tightest geographical constriction through which the current flows is Drake Passage, where only 800 km separates South America from Antarctica. While elsewhere the ACC appears to have a broad domain, it must also navigate steep undersea mountains that constrain its path and steer it north and south across the Southern Ocean.</p>
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Read more:
<a href="https://theconversation.com/antarctica-has-lost-3-trillion-tonnes-of-ice-in-25-years-time-is-running-out-for-the-frozen-continent-98176">Antarctica has lost 3 trillion tonnes of ice in 25 years. Time is running out for the frozen continent</a>
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<h2>What is the Antarctic Circumpolar Current?</h2>
<p>A satellite view over Antarctica reveals a frozen continent surrounded by icy waters. Moving northward, away from Antarctica, the water temperatures rise slowly at first and then rapidly across a sharp gradient. It is the ACC that maintains this boundary. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/245093/original/file-20181112-83564-xa6jev.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/245093/original/file-20181112-83564-xa6jev.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/245093/original/file-20181112-83564-xa6jev.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=660&fit=crop&dpr=1 600w, https://images.theconversation.com/files/245093/original/file-20181112-83564-xa6jev.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=660&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/245093/original/file-20181112-83564-xa6jev.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=660&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/245093/original/file-20181112-83564-xa6jev.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=829&fit=crop&dpr=1 754w, https://images.theconversation.com/files/245093/original/file-20181112-83564-xa6jev.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=829&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/245093/original/file-20181112-83564-xa6jev.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=829&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Map of the ocean surface temperature as measured by satellites and analysed by the European Copernicus Marine Services. The sea ice extent around the antarctic continent for this day appears in light blue. The two black lines indicate the long term position of the southern and northern front of the Antarctic Circumpolar Current.</span>
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<p>The ACC is created by the combined effects of strong westerly winds across the Southern Ocean, and the big change in surface temperatures between the Equator and the poles. </p>
<p>Ocean density increases as water gets colder and as it gets more salty. The warm, salty surface waters of the subtropics are much lighter than the cold, fresher waters close to Antarctica. We can imagine that the depth of constant density levels slopes up towards Antarctica. </p>
<p>The westerly winds make this slope steeper, and the ACC rides eastward along it, faster where the slope is steeper, and weaker where it’s flatter.</p>
<h2>Fronts and bottom water</h2>
<p>In the ACC there are sharp changes in water density known as fronts. The Subantarctic Front to the north and Polar Front further south are the two main fronts of the ACC (the black lines in the images). Both are known to split into two or three branches in some parts of the Southern Ocean, and merge together in other parts.</p>
<p>Scientists can figure out the density and speed of the current by measuring the ocean’s height, using altimeters. For instance, denser waters sit lower and lighter waters stand taller, and differences between the height of the sea surface give the speed of the current. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/245101/original/file-20181112-83586-h2h3dt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/245101/original/file-20181112-83586-h2h3dt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/245101/original/file-20181112-83586-h2h3dt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=660&fit=crop&dpr=1 600w, https://images.theconversation.com/files/245101/original/file-20181112-83586-h2h3dt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=660&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/245101/original/file-20181112-83586-h2h3dt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=660&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/245101/original/file-20181112-83586-h2h3dt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=829&fit=crop&dpr=1 754w, https://images.theconversation.com/files/245101/original/file-20181112-83586-h2h3dt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=829&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/245101/original/file-20181112-83586-h2h3dt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=829&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">Map of how fast the waters around Antarctica are moving in an easterly direction. It is produced using 23 years of satellite altimetry (ocean height) observations as provided by the European Copernicus Marine Services.</span>
<span class="attribution"><span class="source">Author provided</span></span>
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<p>The path of the ACC is a meandering one, because of the steering effect of the sea floor, and also because of instabilities in the current. </p>
<p>The ACC also plays a part in the meridional (or global) overturning circulation, which brings deep waters formed in the North Atlantic southward into the Southern Ocean. Once there it becomes known as Circumpolar Deep Water, and is carried around Antarctica by the ACC. It slowly rises toward the surface south of the Polar Front. </p>
<p>Once it surfaces, some of the water flows northward again and sinks north of the Subarctic Front. The remaining part flows toward Antarctica where it is transformed into the densest water in the ocean, sinking to the sea floor and flowing northward in the abyss as Antarctic Bottom Water. These pathways are the main way that the oceans absorb heat and carbon dioxide and sequester it in the deep ocean. </p>
<h2>Changing current</h2>
<p>The ACC is not immune to climate change. The Southern Ocean has <a href="http://www.nature.com/articles/ngeo362">warmed and freshened in the upper 2,000 m</a>. Rapid warming and freshening has also been found in the <a href="https://journals.ametsoc.org/doi/10.1175/JCLI-D-12-00834.1">Antarctic Bottom Water</a>, the deepest layer of the ocean. </p>
<p>Waters south of the Polar Front are becoming fresher due to increased rainfall there, and waters to the north of the Polar Front are becoming saltier due to increased evaporation. These changes are <a href="https://doi.org/10.1038/s41561-018-0226-1">caused by human activity</a>, primarily through adding greenhouse gases to the atmosphere, and depletion of the ozone layer. The <a href="https://www.nasa.gov/feature/goddard/2018/nasa-study-first-direct-proof-of-ozone-hole-recovery-due-to-chemicals-ban/">ozone hole is now recovering</a> but greenhouse gases continue to rise globally. </p>
<p>Winds have <a href="https://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-17-0481.1">strengthened by about 40% over the Southern Ocean</a> over the past 40 years. Surprisingly, this has <a href="http://www.nature.com/articles/ngeo362">not translated</a> into an increase in the strength of the ACC. Instead there has been an <a href="https://doi.org/10.1002/2014JC010470">increase in eddies</a> that move heat towards the pole, particularly in hotspots such as Drake Passage, Kerguelen Plateau, and between Tasmania and New Zealand. </p>
<p>We have observed much change already. The question now is how this increased transfer of heat across the ACC will impact the stability of the Antarctic ice sheet, and consequently the rate of global sea-level rise.</p><img src="https://counter.theconversation.com/content/106164/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Helen Phillips receives funding from Australian Research Council Discovery Projects and the Australian Government's National Environmental Science Programme, and is an Associate Investigator of the Australian Research Council Centre of Excellence in Climate Extremes.</span></em></p><p class="fine-print"><em><span>Benoit Legresy receives funding from National Environment Science Program, the Integrate Marine Observing System and the Antarctic Climate and Ecosystem CRC. He is affiliated with CSIRO and the ACE-CRC. </span></em></p><p class="fine-print"><em><span>Nathan Bindoff receives funding from Australian Research Council through its Discovery and Centre of Excellence programs and from the National Environment Science Program and the Antarctic Climate Ecosystems CRC.</span></em></p>The Antarctic Circumpolar Current provides a barrier to heat that keeps warm subtropical waters away from Antarctica. Yet, there are a few places where the heat gets through.Helen Phillips, Senior Research Fellow, Institute for Marine and Antarctic Studies, University of TasmaniaBenoit Legresy, CSIRONathan Bindoff, Professor of Physical Oceanography, Institute for Marine and Antarctic Studies, University of TasmaniaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1018152018-08-21T20:00:42Z2018-08-21T20:00:42ZPoliticised science on the Great Barrier Reef? It’s been that way for more than a century<figure><img src="https://images.theconversation.com/files/232829/original/file-20180821-30599-8psjky.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Successive governments have seen the Great Barrier Reef not just as a scientific wonder, but as a channel to further economic development.</span> <span class="attribution"><span class="source">Superjoseph/Shutterstock.com</span></span></figcaption></figure><p>The <a href="https://www.smh.com.au/environment/conservation/no-justice-huge-reef-foundation-grant-stuns-charity-sector-20180818-p4zy8i.html">controversy</a> surrounding the A$444 million given to the Great Barrier Reef Foundation by the federal government shows how politicised science has become on the Great Barrier Reef.</p>
<p>One reef scientist, who declined to be named, was <a href="https://www.smh.com.au/environment/conservation/like-winning-lotto-reef-foundation-minnow-braces-for-444m-windfall-20180511-p4zeud.html">quoted</a> saying that the grant was “obviously” political, and accused the federal government of seeking to deny the opposition the chance to make the Great Barrier Reef an election issue.</p>
<p>But the politicisation of reef science, and particularly the Great Barrier Reef itself, is not new. It has a long history, stretching back to the time when the British empire was at its most powerful.</p>
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Read more:
<a href="https://theconversation.com/is-it-too-cheap-to-visit-the-priceless-great-barrier-reef-83717">Is it too cheap to visit the 'priceless' Great Barrier Reef?</a>
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<p>In the nineteenth century, scientists studying the Great Barrier Reef were driven by the political winds and whims of British colonialists. For the most part, these scientists aided the mission of exploration and settlement. With every exploratory voyage, the value of the Great Barrier Reef as an arm of the empire grew, as scientists began to weave their insights into the reef’s biology and geology with evocations of its potential resources and suitability for settlement. Scientists such as <a href="http://adb.anu.edu.au/biography/jukes-joseph-beete-2284">Joseph Beete Jukes</a> were particularly important in illuminating the Great Barrier Reef’s scientific mysteries and economic possibilities.</p>
<p>Around the time of federation in 1901, however, the politics of reef science took on a heightened nationalistic and provincial tone. Scientists asserted that the Great Barrier Reef’s value to Queensland and the nation lay specifically in its exploitable resources, and argued that it was the government’s responsibility to develop them. </p>
<p>As the science was in its infancy, reef scientists imagined that their field would inevitably develop in concert with the establishment of reef-based industries such as fishing and <a href="https://theconversation.com/death-on-the-great-barrier-reef-how-dead-coral-went-from-economic-resource-to-conservation-symbol-67157">coral rubble mining</a>.</p>
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Read more:
<a href="https://theconversation.com/death-on-the-great-barrier-reef-how-dead-coral-went-from-economic-resource-to-conservation-symbol-67157">Death on the Great Barrier Reef: how dead coral went from economic resource to conservation symbol</a>
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<p>In the early twentieth century, scientists suggested that a research station needed to be established along the Queensland coast. The idea was championed by natural historian Edmund Banfield, who <a href="https://trove.nla.gov.au/newspaper/article/60072747?searchTerm=Rural%20Homilies%20%20%20%20%20%20%20%20%20%20%20%20&searchLimits=l-decade=191%7C%7C%7Cl-year=1915%7C%7C%7Cl-month=1">wrote</a> that it would “demonstrate how best the riches of the Great Barrier Reef might be exploited”. </p>
<p>Many scientists of the day believed that the government had failed to sufficiently develop the Great Barrier Reef, and feared that its dormant resources were at risk of plunder by our northern Asian neighbours. Reef science became caught up in the prevailing discourse of an empty and undeveloped northern Australia.</p>
<p>In response, Queensland-based scientists established the <a href="https://trove.nla.gov.au/people/478331">Great Barrier Reef Committee</a> in 1922. The committee saw itself as having two roles: “pure” scientific research on the reef’s biology and geology; and the identification of commercial products that the reef could provide. </p>
<p>In 1928 the committee, backed by the British, Australian and Queensland governments, organised a research expedition to <a href="http://www.gbrmpa.gov.au/visit-the-reef/site-specific-management/low-isles">Low Isles</a>, off the coast of Port Douglas. </p>
<p>The year-long expedition, led by British-born marine scientist <a href="https://trove.nla.gov.au/people/1019244?c=people">Charles Maurice Yonge</a>, aimed to find evidence of the reef’s economic potential. But the research, while significant to coral-reef science, offered little advice for the Queensland government despite its significant financial investment. </p>
<p>Nonetheless, the Great Barrier Reef Committee continued to leverage the state government’s interest in developing northern Queensland, and in 1950 it secured a lease on <a href="https://www.uq.edu.au/heron-island-research-station/about-us">Heron Island</a>. The committee was also given funding to build a research station on the island, after promising that it would reveal commercial products and boost tourism.</p>
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<a href="https://images.theconversation.com/files/232830/original/file-20180821-30581-6ar75k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/232830/original/file-20180821-30581-6ar75k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/232830/original/file-20180821-30581-6ar75k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/232830/original/file-20180821-30581-6ar75k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/232830/original/file-20180821-30581-6ar75k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/232830/original/file-20180821-30581-6ar75k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/232830/original/file-20180821-30581-6ar75k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/232830/original/file-20180821-30581-6ar75k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Heron Island, where the research station is still operating, now run by the University of Queensland.</span>
<span class="attribution"><span class="source">UQ/Wikimedia Commons</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
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<p>The Heron Island research station was built at a time when only a few Australian universities offered full courses in marine biology. Reef science had always been dominated by geology, as researchers sought to understand how coral reefs were formed.</p>
<p>After the second world war, aided by more sophisticated drilling equipment, and governments eager to locate local oil reserves, scientists such as the Queensland geologist Dorothy Hill began studying the Great Barrier Reef’s mineral and petroleum reserves, and recommended several sites for further exploration. </p>
<p>Between 1959 and 1967 three exploration wells were drilled along the reef, but none showed signs of oil or gas. In the same period, the Queensland government granted 37 prospecting and exploration permits, <a href="https://researchonline.jcu.edu.au/49776/">23 of them in the vicinity of the Great Barrier Reef</a>.</p>
<p>Geologists’ role in this exploration meant that they were viewed with suspicion by their marine biologist colleagues when the “<a href="http://www.abc.net.au/news/2017-10-14/save-the-barrier-reef-campaign-stickers/9050228">Save the Reef</a>” campaign began in 1967. </p>
<p>Geologists were largely seen as sympathetic to the oil industry’s interests, whereas marine biologists typically aligned themselves with the views of conservationists. At the same time, scientists found themselves taking sides in response to the first outbreak of Crown of Thorns starfish in the 1960s. </p>
<p><a href="https://trove.nla.gov.au/newspaper/article/48085465/5339865">Robert Endean</a>, the scientist who campaigned for government intervention in the outbreak, found himself marginalised by the scientific community, faced backlash from tourist operators concerned by his claims of dying reefs, and eventually lost government support for his research. </p>
<p>During both the Save the Reef campaign and the Crown of Thorns outbreak, scientists were publicly scrutinised for how their research, and their public comments, impacted the debate. A similar pattern has played out over the mass coral bleaching that <a href="https://theconversation.com/au/topics/2016-coral-bleaching-event-26991">hit the Great Barrier Reef in 2016</a>.</p>
<p>Today, it seems governments are seeking to <a href="https://www.theguardian.com/environment/2016/may/27/australia-scrubbed-from-un-climate-change-report-after-government-intervention">make the Great Barrier Reef appear to be protected</a> while scientists themselves leverage the political and public fascination, with the result that the Great Barrier Reef accounts for a significant proportion of Australia’s entire marine research output.</p>
<p>The issues of <a href="https://theconversation.com/cloudy-issue-we-need-to-fix-the-barrier-reefs-murky-waters-39380">sediment and nutrient run-off</a>, <a href="https://theconversation.com/au/topics/2016-coral-bleaching-event-26991">coral bleaching</a>, <a href="https://theconversation.com/ocean-acidification-is-already-harming-the-great-barrier-reefs-growth-55226">ocean acidification</a>, <a href="https://theconversation.com/how-scaring-starfish-could-help-to-save-the-great-barrier-reef-36759">Crown of Thorns starfish</a>, <a href="https://theconversation.com/au/topics/carmichael-coal-mine-14433">coal mines</a>, and <a href="https://theconversation.com/shipping-in-the-great-barrier-reef-the-miners-highway-39251">port developments</a> have all complicated the politics of reef science. </p>
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Read more:
<a href="https://theconversation.com/not-out-of-hot-water-yet-what-the-world-thinks-about-the-great-barrier-reef-42945">Not out of hot water yet: what the world thinks about the Great Barrier Reef</a>
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<p>For half a century, the science has been overlaid with a wider discourse about the need to preserve the Great Barrier Reef. This idea, championed by scientists, politicians and civil society, shows no sign of subsiding.</p>
<p>Today, the amounts of money involved may well be unprecedented. But the idea of reef science coming with political strings attached is nothing new.</p><img src="https://counter.theconversation.com/content/101815/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Rohan James Lloyd received an Australian Postgraduate Award and a National Library of Australia Summer Scholarship while understanding research for this project. He is a member of the Australian Labor Party.</span></em></p>The $444 million awarded to the Great Barrier Reef Foundation has been criticised as a politically calculated move. But governments have been asking what the reef can do for them ever since colonial times.Rohan James Lloyd, Adjunct Lecturer, James Cook UniversityLicensed as Creative Commons – attribution, no derivatives.