tag:theconversation.com,2011:/us/topics/pacific-ocean-12006/articlesPacific Ocean – The Conversation2024-02-08T13:40:00Ztag:theconversation.com,2011:article/2230132024-02-08T13:40:00Z2024-02-08T13:40:00ZEl Niño is starting to lose strength after fueling a hot, stormy year, but it’s still powerful − an atmospheric scientist explains what’s ahead for 2024<figure><img src="https://images.theconversation.com/files/574206/original/file-20240207-16-vnmp3w.jpg?ixlib=rb-1.1.0&rect=0%2C23%2C5107%2C3298&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">In California, El Niño helped fuel a wet 2023 and early 2024.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/person-walks-through-flood-waters-as-a-powerful-long-news-photo/1986231877">Mario Tama/Getty Images</a></span></figcaption></figure><p>Wild weather has been <a href="https://theconversation.com/2023s-extreme-storms-heat-and-wildfires-broke-records-a-scientist-explains-how-global-warming-fuels-climate-disasters-217500">roiling North America</a> for the past few months, thanks in part to a strong El Niño that sent temperatures surging in 2023. The climate phenomenon fed <a href="https://theconversation.com/what-is-an-atmospheric-river-with-flooding-and-mudslides-in-california-a-hydrologist-explains-the-good-and-bad-of-these-storms-and-how-theyre-changing-222249">atmospheric rivers</a> drenching the West Coast and contributed to <a href="https://theconversation.com/summer-2023-was-the-hottest-on-record-yes-its-climate-change-but-dont-call-it-the-new-normal-213021">summer’s extreme heat</a> in the South and Midwest and fall’s <a href="https://theconversation.com/2023s-extreme-storms-heat-and-wildfires-broke-records-a-scientist-explains-how-global-warming-fuels-climate-disasters-217500">wet storms across the East</a>.</p>
<p>That strong El Niño is now <a href="https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/ensodisc.shtml">starting to weaken</a> and will likely be gone by late spring 2024.</p>
<p>So, what does that mean for the months ahead – and for the 2024 hurricane season?</p>
<h2>What is El Niño?</h2>
<p>Let’s start with a quick look at what an El Niño is.</p>
<p>El Niño and its opposite, La Niña, are <a href="https://oceanservice.noaa.gov/facts/ninonina.html">climate patterns that influence weather</a> around the world. El Niño tends to raise global temperatures, as we saw in 2023, while La Niña events tend to be slightly cooler. The two result in global temperatures fluctuating above and below the <a href="https://www.climate.gov/news-features/understanding-climate/climate-change-global-temperature">warming trend set by climate change</a>. </p>
<p>El Niño starts as warm water builds up along the equator in the eastern tropical Pacific Ocean, off South America.</p>
<figure class="align-center ">
<img alt="A colored map shows temperature differences with a warm area just west of South America along the equator." src="https://images.theconversation.com/files/574240/original/file-20240207-18-ojnwih.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/574240/original/file-20240207-18-ojnwih.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=325&fit=crop&dpr=1 600w, https://images.theconversation.com/files/574240/original/file-20240207-18-ojnwih.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=325&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/574240/original/file-20240207-18-ojnwih.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=325&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/574240/original/file-20240207-18-ojnwih.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=408&fit=crop&dpr=1 754w, https://images.theconversation.com/files/574240/original/file-20240207-18-ojnwih.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=408&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/574240/original/file-20240207-18-ojnwih.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=408&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Reds and yellows show where Pacific waters were warmer in 2024 than in 2022. The abnormally warmer region along the equator is what we call El Niño. Weak El Niño events occur every few years, with strong events like this averaging once every 10 to 20 years.</span>
<span class="attribution"><span class="source">NOAA</span></span>
</figcaption>
</figure>
<p>Typically, tropical Pacific winds blow from the east, exposing cold water along the equator and building up warm water in the western Pacific. Every <a href="https://www.noaa.gov/understanding-el-nino">three to seven years or so</a>, however, these winds relax or turn to blow from the west. When that happens, warm water rushes to the east. The warmer-than-normal water drives more rainfall and alters winds around the world. <a href="https://www.youtube.com/watch?v=MPok2G9Fyno">This is El Niño</a>.</p>
<p>The water stays warm for several months until, ultimately, it cools or is driven away from the equator by the return of the trade winds.</p>
<p><iframe id="aOiS8" class="tc-infographic-datawrapper" src="https://datawrapper.dwcdn.net/aOiS8/17/" height="400px" width="100%" style="border: none" frameborder="0"></iframe></p>
<p>When the eastern Pacific region along the equator becomes abnormally cold, La Niña has emerged, and global weather patterns change again.</p>
<h2>What to expect from El Niño in 2024</h2>
<p>While the 2023-24 El Niño event <a href="https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/ensodisc.shtml">likely peaked in December</a>, it is still strong.</p>
<p>For the rest of winter, forecasts suggest that strong El Niño conditions will likely continue to favor unusual warmth in Canada and the northern United States and occasional stormy conditions across the southern states.</p>
<figure class="align-center ">
<img alt="Two maps of typical winter conditions under El Nino and La Nina show the Southwest wetter and the Northwest and upper Midwest generally warmer under El Nino." src="https://images.theconversation.com/files/574242/original/file-20240207-24-syjmnk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/574242/original/file-20240207-24-syjmnk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=853&fit=crop&dpr=1 600w, https://images.theconversation.com/files/574242/original/file-20240207-24-syjmnk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=853&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/574242/original/file-20240207-24-syjmnk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=853&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/574242/original/file-20240207-24-syjmnk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1072&fit=crop&dpr=1 754w, https://images.theconversation.com/files/574242/original/file-20240207-24-syjmnk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1072&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/574242/original/file-20240207-24-syjmnk.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">
<figcaption>
<span class="caption">Typical winters under El Niño and La Niña show the striking differences between the two patterns. Not all El Niños turn out this way.</span>
<span class="attribution"><a class="source" href="https://www.climate.gov/news-features/understanding-climate/el-ni%C3%B1o-and-la-ni%C3%B1a-frequently-asked-questions">NOAA Climate.gov</a></span>
</figcaption>
</figure>
<p>El Niño is likely to end in late spring or early summer, shifting briefly to neutral. There’s a good chance we will see La Niña conditions this fall. But forecasting when that happens and what comes next is harder.</p>
<h2>How an El Niño ends</h2>
<p>While it’s easy to tell when an El Niño event reaches its peak, predicting when one will end depends on how the wind blows, and everyday weather affects the winds.</p>
<p>The warm area of surface water that defines El Niño typically becomes more shallow toward spring. In mid-May 1998, at the end of an <a href="https://www.youtube.com/watch?v=9rPqIuXlWuA">even stronger El Niño event</a>, there was a time when people fishing in the warm surface water in the eastern tropical Pacific could have touched the cold water layer a few feet below by just jumping in. At that point, it took only a moderate breeze to pull the cold water to the surface, ending the El Niño event.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/WPA-KpldDVc?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">How El Niño develops in the equatorial Pacific Ocean.</span></figcaption>
</figure>
<p>But exactly when a strong El Niño event reverses varies. A <a href="https://www.washingtonpost.com/news/capital-weather-gang/wp/2015/06/12/how-the-super-el-nino-of-1982-83-kept-itself-a-secret/">big 1983 El Niño</a> didn’t end until July. And the <a href="https://doi.org/10.1126/science.241.4862.192">El Niño in 1987</a> retreated into the central Pacific but did not fully reverse until December.</p>
<p>As of early February 2024, strong westerly winds were driving warm water from west to east across the equatorial Pacific.</p>
<p>These winds tend to make El Niño last a little longer. However, they’re also likely to drive what little warm water remains along the equator out of the tropics, up and down the coasts of the Americas. The more warm water that is expelled, the greater the chances of full reversal to La Niña conditions in the fall.</p>
<h2>Summer and the hurricane risk</h2>
<p>Among the more important El Niño effects is its tendency to reduce <a href="https://www.climate.gov/news-features/blogs/enso/impacts-el-ni%C3%B1o-and-la-ni%C3%B1a-hurricane-season">Atlantic hurricane activity</a>.</p>
<p>El Niño’s Pacific Ocean heat affects upper level winds that blow across the Gulf of Mexico and the tropical Atlantic Ocean. That <a href="https://www.accuweather.com/en/weather-news/what-is-wind-shear-and-how-does-it-impact-hurricanes-other-tropical-cyclones/330987">increases wind shear</a> - the change in wind speed and direction with height – which can tear hurricanes apart.</p>
<p>The 2024 hurricane season likely won’t have El Niño around to help weaken storms. But that doesn’t necessarily mean an active season.</p>
<p>During the <a href="https://www.noaa.gov/news-release/2023-atlantic-hurricane-season-ranks-4th-for-most-named-storms-in-year">2023 Atlantic hurricane season</a>, El Niño’s effect on the winds was more than offset by abnormally warm Atlantic waters, which fuel hurricanes. The season ended with more storms than average.</p>
<h2>The strange El Niño of 2023-24</h2>
<p>Although the 2023-24 El Niño event wasn’t the strongest in recent decades, many aspects of it have been unusual.</p>
<p>It followed three years of La Niña conditions, which is unusually long. It also emerged quickly, from March to May 2023. The combination led to weather extremes unseen <a href="https://yaleclimateconnections.org/2020/04/a-horrific-drought-in-the-1870s-offers-a-warning-for-today/">since perhaps the 1870s</a>. </p>
<figure class="align-center ">
<img alt="Two cars are trapped up to their widows in a mudslide that poured through a Los Angeles neighborhood. One car is parked in its driveway," src="https://images.theconversation.com/files/574187/original/file-20240207-30-4e5k3b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/574187/original/file-20240207-30-4e5k3b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/574187/original/file-20240207-30-4e5k3b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/574187/original/file-20240207-30-4e5k3b.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/574187/original/file-20240207-30-4e5k3b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/574187/original/file-20240207-30-4e5k3b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/574187/original/file-20240207-30-4e5k3b.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">Extreme rainfall in early 2024 sent mudslides into dozens of Los Angeles-area neighborhoods.</span>
<span class="attribution"><a class="source" href="https://newsroom.ap.org/detail/APTOPIXCaliforniaStorms/b49e6373657e41f9964a64a6a631e5b6/photo">AP Photo/Marcio Jose Sanchez</a></span>
</figcaption>
</figure>
<p>La Niña cools the tropics but stores warm water in the western Pacific. It also warms the middle latitude oceans by weakening the winds and allowing more sunshine through. After three years of La Niña, the rapid emergence of El Niño helped make the Earth’s surface <a href="https://www.noaa.gov/news/2023-was-worlds-warmest-year-on-record-by-far">warmer than in any recent year</a>.</p><img src="https://counter.theconversation.com/content/223013/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Paul Roundy receives funding from the National Science Foundation and National Oceanic and Atmospheric Administration. </span></em></p>The strong El Niño that started in 2023 will still have big impacts at least through March. Here’s what to watch for next.Paul Roundy, Professor of Atmospheric and Environmental Sciences, University at Albany, State University of New YorkLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2189022024-01-11T13:25:55Z2024-01-11T13:25:55ZTo protect endangered sharks and rays, scientists are mapping these species’ most important locations<figure><img src="https://images.theconversation.com/files/565884/original/file-20231214-27-kjjzka.jpg?ixlib=rb-1.1.0&rect=60%2C0%2C6720%2C4426&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A tiger shark swims among surgeonfish off Fuvahmulah Atoll, Maldives, in the Indian Ocean.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/tiger-shark-with-shoal-of-fish-surgeonfishes-indian-royalty-free-image/1262279323">imageBROKER/Norbert Probst via Getty Images</a></span></figcaption></figure><p>All of the saltwater bodies on Earth make up <a href="https://oceanservice.noaa.gov/facts/howmanyoceans.html">one big ocean</a>. But within it, there is infinite variety – just ask any scuba diver. Some spots have more coral, more sea turtles, more fish, more life. </p>
<p>“I’ve been diving in many places around the world, and there are few locations like the <a href="https://visitfuvahmulah.mv/discover-fuvahmulah/">Fuvahmulah Atoll</a> in the Maldives,” Amanda Batlle-Morera, a research assistant with the <a href="https://sharkrayareas.org/">Important Shark and Ray Areas project</a>, told me. “You can observe tiger sharks, thresher sharks, scalloped hammerheads, oceanic manta rays and more, without throwing out bait to attract them.” </p>
<p>Identifying areas like Fuvahmulah that are especially important to certain species is a <a href="https://www.fws.gov/sites/default/files/documents/critical-habitat-fact-sheet.pdf">long-standing strategy</a> for protecting threatened land animals, birds and marine mammals, such as whales and dolphins. Now our team of marine conservation scientists at the <a href="https://sharkrayareas.org/">Important Shark and Ray Areas project</a> is using it to help protect sharks and their relatives. </p>
<p>I am a <a href="https://scholar.google.com/citations?user=xb7noGAAAAAJ&hl=en">marine conservation biologist</a> and the project’s communications officer. This initiative is working to identify locations that are critical for sharks and rays, so that these zones can be flagged for future protection or fisheries management measures. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/0mPBvhGvZLI?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Divers get close views of tiger sharks at Fuvahmulah, an offshore island in the southern Maldives. Six threatened shark species and one threatened ray species appear regularly in the area.</span></figcaption>
</figure>
<h2>Where the sharks are</h2>
<p>Sharks and their relatives are some of the most imperiled animals on Earth: More than one-third of all known species are <a href="https://doi.org/10.1016/j.cub.2021.08.062">threatened with extinction</a>. Many of these animals play vital roles in their ecosystems. Losing marine predators <a href="https://doi.org/10.1016/j.tree.2008.01.003">can destabilize entire food webs</a> and the ecosystems that these food webs depend on.</p>
<p>In recent years, the management of sharks and their relatives, rays and chimaeras, has largely focused on curbing the impacts of fisheries and trade on these species. But their populations <a href="https://doi.org/10.1016/j.cub.2021.08.062">are still declining rapidly</a>, so new strategies are needed. </p>
<p>To effectively protect these important and threatened animals, my colleagues and I believe it is vital to identify and protect parts of the ocean, plus some freshwater habitats, that are especially significant for their lives. Some areas, for example, are important migratory pathways, or feeding or mating grounds, or places to lay eggs. </p>
<p>Our team has created a <a href="https://doi.org/10.3389/fmars.2022.968853">list of technical criteria</a> so that zones around the world can be examined and potentially designated as Important Shark and Ray Areas. We modeled these criteria on similar approaches that are already in use, such as <a href="https://doi.org/10.1641/0006-3568(2004)054%5B1110:KBAASC%5D2.0.CO;2">important marine mammal areas</a>, which we adapted to the specific needs and biology of sharks and their relatives. </p>
<p>We are now hosting a series of 13 regional workshops around the world and inviting local experts to nominate preliminary areas of interest for evaluation by our team and an independent expert review panel. So far, we’ve completed three workshops, one focusing on the Central and South American Pacific, another on the Mediterranean and Black seas, and the third on the Western Indian Ocean, with a workshop for Asia planned for early 2024. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/568049/original/file-20240105-14-7s4g8o.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A world map shows zones that scientists have identified as Important Shark and Ray Areas in the Pacific and Indian oceans and the Mediterranean Sea." src="https://images.theconversation.com/files/568049/original/file-20240105-14-7s4g8o.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/568049/original/file-20240105-14-7s4g8o.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=308&fit=crop&dpr=1 600w, https://images.theconversation.com/files/568049/original/file-20240105-14-7s4g8o.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=308&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/568049/original/file-20240105-14-7s4g8o.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=308&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/568049/original/file-20240105-14-7s4g8o.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=387&fit=crop&dpr=1 754w, https://images.theconversation.com/files/568049/original/file-20240105-14-7s4g8o.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=387&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/568049/original/file-20240105-14-7s4g8o.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=387&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 current version of the online atlas of Important Shark and Ray Areas. The atlas is organized by region, showing which parts of the world’s oceans and coasts have been assessed.</span>
<span class="attribution"><a class="source" href="https://sharkrayareas.org/">Important Shark and Ray Areas initiative</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>After the workshops and expert reviews, each finalized Important Shark and Ray Area will be added to our e-atlas, which <a href="https://sharkrayareas.org/e-atlas/">can be viewed online</a>. Each region’s Important Shark and Ray Areas are published in a formal compendium, and the whole global process will be repeated every 10 years. This cycle will allow us to consider changes to areas that have already been mapped, such as new fishery policies or impacts from climate change, and to take into account new research that can help us identify new areas. </p>
<h2>Informing conservation policies</h2>
<p>We recently published our <a href="https://sharkrayareas.org/download/mediterranean-and-black-seas-regional-compendium-of-important-shark-and-ray-areas/">Mediterranean and Black seas region compendium</a>, which reflects input from over 180 experts from around the region. It identifies 65 Important Shark and Ray Areas that range widely in size and habitat type. Our <a href="https://sharkrayareas.org/download/western-indian-ocean-regional-compendium-of-important-shark-and-ray-areas/">western Indian Ocean compendium</a> includes over 125 areas. </p>
<p>These zones are important for species like the critically endangered <a href="https://www.fisheries.noaa.gov/species/blackchin-guitarfish">blackchin guitarfish</a> (<em>Glaucostegus cemiculus</em>), as well as heavily fished shark species like the <a href="https://www.sharks.org/smoothhound-mustelus-mustelus">common smoothhound shark</a> (<em>Mustelus mustelus</em>). </p>
<p>Some of these areas, such as <a href="https://sharkrayareas.org/portfolio-item/benidorm-island-isra/">Benidorm Island</a> off Spain’s Mediterranean coast, are in shallow coastal zones. Others, like the <a href="https://sharkrayareas.org/wp-content/uploads/isra-factsheets/12CentralSouthPacific/Cocos-Galapagos-Swimway-12CentralSouthPacific.pdf">Cocos-Galapagos Swimway</a> off Costa Rica and Ecuador, reach into deep ocean waters. </p>
<p>The smallest area identified so far, Israel’s <a href="https://sharkrayareas.org/wp-content/uploads/isra-factsheets/03MedBlackSeas/Palmahim-Brine-Pools-03MedBlackSeas.pdf">Palmahim brine pools</a> in the southeast Mediterranean, measures just 0.03 square miles (0.09 square kilometers) – about half the size of New York City’s Grand Central station. <a href="https://eol.org/pages/46560072">Blackmouth catsharks</a>
(<em>Galeus melastomus</em>) breed and lay eggs there, and threatened <a href="https://eol.org/pages/46560287">angular rough sharks</a> (<em>Oxynotus centrina</em>) feed there, including on blackmouth catshark eggs. </p>
<p>The largest area is the <a href="https://sharkrayareas.org/wp-content/uploads/isra-factsheets/03MedBlackSeas/Strait-of-Sicily-and-Tunisian-Plateau-03MedBlackSeas.pdf">Strait of Sicily and Tunisian Plateau</a>, which extends over 77,000 square miles (200,000 square kilometers) – about the size of Great Britain – in the Mediterranean between Sicily, Malta, western Libya and Tunisia. This zone supports at least 32 species of sharks, rays and chimaeras, including many that are at risk of extinction, in habitats ranging from shallow seagrass beds to deep ocean trenches.</p>
<p><div data-react-class="InstagramEmbed" data-react-props="{"url":"https://www.instagram.com/p/CsHnxebvcsp/?utm_source=ig_web_copy_link\u0026igsh=MzRlODBiNWFlZA==","accessToken":"127105130696839|b4b75090c9688d81dfd245afe6052f20"}"></div></p>
<p>Identifying a location as an Important Shark and Ray Area does not mean it will automatically be protected. Our goal is to inform countries’ existing spatial planning and fisheries management processes and other conservation planning. Eventually, these zones may be incorporated into <a href="https://oceanexplorer.noaa.gov/facts/mpas.html">marine protected areas</a> or other types of ocean preserves.</p>
<p>Sharks and their relatives need human help to survive and maintain their important biological roles in the ocean. Through the Important Shark and Ray Areas project, hundreds of scientists and other experts are helping to identify special places for these species that we believe need some extra attention.</p>
<p><em>Dr. Rima Jabado, chair of the IUCN Species Survival Commission Shark Specialist Group, contributed to this article.</em></p><img src="https://counter.theconversation.com/content/218902/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>David Shiffman does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>A new initiative is pinpointing areas in the world’s oceans that are key habitats for sharks and their relatives, so that governments can consider protecting these areas.David Shiffman, Faculty Research Associate in Marine Biology, Arizona State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2194832023-12-31T20:25:57Z2023-12-31T20:25:57ZFrom Blue Pacific to Indo-Pacific: how politics and language define our ‘Indigenous ocean’<p><em>This is an edited extract from An Indigenous Ocean: Pacific Essays by Damon Salesa (Bridget Williams Books)</em></p>
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<p>In September 2017, at the 48th meeting of the Pacific Islands Forum, the political leaders of the Pacific agreed a <a href="https://www.forumsec.org/2050strategy/">new regional approach</a>. They announced the way forward as the “Blue Pacific – Our Sea of Islands, Our Livelihoods, Our Oceania”. It was a remarkable moment of solidarity and ambition, charting a vision towards 2050. </p>
<p>Powering the vision was – as most Pacific Studies undergraduates would have noticed – a seminal essay by the Tongan scholar <a href="https://globalsocialtheory.org/thinkers/hauofa-epeli/">Epeli Hau‘ofa</a>, Our Sea of Islands, from 1993. Stock reading for Pacific Studies students, the essay is remarkable in its prescience (most readers find it compelling, decades after its publication) and now it had been elevated to the headlines of regional geopolitics. It’s a revealing example of how the study of the Pacific and the practice of Pacific politics often intersect.</p>
<p>In the wake of Hau‘ofa, Pacific politicians waxed lyrical about the “Sea of Islands”. “The Ocean is our cultural identity”, one politician riffed. “It is a cornerstone of our social cohesion. It is also the foundation of our economy and it is our road to prosperity.” </p>
<p>In opening the meeting, the host leader from Sāmoa spoke of the “Samoan Blue Pacific Identity”; that the ocean was the “fundamental essence of the region”; and that “the sheer fact of our geography, such as trends associated with shifts in the centres of global power […] places the Pacific at the centre of contemporary global geopolitics”. Of all the tools available to advocate for the Pacific and consolidate the region, the one chosen was story.</p>
<p>The “Blue Pacific” had already figured earlier that year, in June, at the United Nations Ocean Conference in New York. There, the efforts to implement UN Sustainable Development Goal 14, “Life Below Water”, had given rise to concrete solutions, a point that was particularly important to Pacific nations, which consider themselves the co-authors of that goal. </p>
<p>Rapidly, the Blue Pacific – a story about a place – had become a new place. Regional organisations connected through the Blue Pacific, and it became a cornerstone of diplomatic and national language. There were speeches, of course, and journalism, academic articles, music, debates and conferences. </p>
<p>At the 25th Conference of the Parties to the UN Framework Convention on Climate Change, or COP25, in 2019, the South Pacific Regional Environment Programme called its pavilion “The Moana Blue Pacific Pavilion”. A sure sign of the story’s reach was that the “Blue Pacific” was appearing in the prosaic communications of the US State Department, which noted that “The Big Blue Pacific Continent Is a Force”. Which meant that it was.</p>
<h2>New names, old stories</h2>
<p>Holding together the new movement – which was launched at a moment of considerable difficulty for the region – was an old story. The Forum leaders and others around it explicitly referred to the Blue Pacific as a narrative. As the Samoan Prime Minister put it, “[t]he Blue Pacific provides a new narrative for Pacific Regionalism and how the Forum engages with the world”. </p>
<p>The Pacific was using the narrative to engage the world and address the climate emergency. The art of storytelling was enmeshed with political and geopolitical arts. The strategy was based in realpolitik – attempting to shore up the deals that leaders would and could make – but it also drew on both the deep Pacific past, millennia of voyaging around the Ocean, and more recent developments. </p>
<p>These included the cooperative regional approach developed politically from the 1960s, and key thinking and writing on the regional theme, which became embedded in Pacific discourse in the second half of the 20th century. The regional leaders frequently quoted the Tongan anthropologist and artist Epeli Hau‘ofa; they cited the writings and words of the politician scholar <a href="https://www.rnz.co.nz/collections/nff-fiji/kamisese-mara">Ratu Mara</a>; they held up of the idea of a New Oceania developed by the Samoan scholar, artist and writer <a href="https://www.anzliterature.com/member/albert-wendt/">Maualaivao Albert Wendt</a>.</p>
<p>I am aware that describing the Pacific as constituted through layers of stories, narrative and naming risks being seen as ethereal, untethered from supposed “concrete” realities. This is the opposite of what I believe.</p>
<p>In a very deep and powerful way, a central struggle of the Pacific in the future will be, as it has been in the past and is today, the contest over names and the stories they hold. Indigenous communities have shown that while sovereignty and political control may be wrested from local peoples (though typically not for long), their ability to control language, culture, names, stories and histories has made for ongoing and deep reservoirs of contest.</p>
<h2>The Indo-Pacific as geopolitical construct</h2>
<p>In the past decade we have seen two powerful conjurings of name and place essential to the future of the Pacific. The “Indo-Pacific” is a pseudo-geographic term used to gesture towards political groupings. Rarely used before, in the 21st century it has come to be used by the United States and its allies to describe a hitherto unknown place, one that is obviously a counter to the influence of China in the region. </p>
<p>The Indo-Pacific is now a geopolitical construct said to encompass the Indian Ocean, the South China Sea, and shifting, unspecified parts of the Pacific Ocean. In other words, it both marginalises and co-opts the Indigenous Pacific of which I write. </p>
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Read more:
<a href="https://theconversation.com/australia-has-long-viewed-the-pacific-as-a-place-of-threats-that-must-be-contained-its-time-for-this-mindset-to-change-212772">Australia has long viewed the Pacific as a place of threats that must be contained. It's time for this mindset to change</a>
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<p>The Indo-Pacific has gone from something no one had ever heard of, to being about the most important thing in the world. Indeed, as the US president writes, “the future of each of our nations – and indeed the world – depends on a free and open Indo-Pacific enduring and flourishing in the decades ahead”. It seems almost flippant to note that the Indo-Pacific, too, is a story; a narrative told about the world that has called a new place into being.</p>
<p>The Indo-Pacific narrative is material: it has already ordered and structured activity in the world. Such is the power of this particular narrative and construct that it is central to many of the most vital geopolitical discourses and activities globally. In particular, it is crucial to <a href="https://www.defense.gov/Spotlights/AUKUS/">AUKUS</a>, the new security pact formed by Australia, the United Kingdom and the US in September 2021. </p>
<p>The AUKUS alliance involves as its centrepiece the acquisition by Australia of nuclear-powered submarines, as well as some other technology transfers, and the explicit object of the AUKUS agreement is to “sustain peace and stability in the Indo-Pacific”. Which is to say that without the Indo-Pacific story, AUKUS would have no clear object or domain. </p>
<p>The Indo-Pacific thus arrives as an explicit counter to other narratives, but with weight and consequence – nuclear, military, political and economic (it is projected to cost Australia between A$268 and $368 billion, in a field famed for cost overruns) – unavailable to Pacific nations. </p>
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Read more:
<a href="https://theconversation.com/approach-with-caution-why-nz-should-be-wary-of-buying-into-the-aukus-security-pact-203915">Approach with caution: why NZ should be wary of buying into the AUKUS security pact</a>
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<p>The Indo-Pacific now has its own experts, managers and agents – and, perhaps most ominously, its own generals and admirals, foreign policies, armies and navies: not least “USINDOPACOM” (US Indo-Pacific Command), which has fully subsumed what was once Pacific Command, including the expropriation of its URL.</p>
<p>The Indo-Pacific carries a different understanding of the world, and it is one that puts what I have called the Indigenous Pacific at the margins. It also reveals the different ways of seeing of, on the one hand Australia, New Zealand and the US, who are retelling the Indo-Pacific AUKUS story; and on the other, the peoples of the Independent Pacific, who are critical of it, particularly its nuclear dimensions and its potential to create and escalate political tensions.</p>
<h2>An unequal ocean</h2>
<p>The materiality of different narratives about the Pacific makes clear not only their differences and complexity, but the inequality of circumstances. Though there is a vibrancy to Indigenous traditions and narration, they do not have the same access and circulation; the Pacific remains an unequal ocean. </p>
<p>The profound inequalities that were a hallmark of colonised experience in the past inflect the disadvantages of the present, and the two dimensions are intimately connected. </p>
<p>These material inequalities speak to the deep connections between present and past in the postcolonial Pacific. In very few areas is this not apparent, but I wish to draw attention to one specific way in which the colonial, and particularly the decolonising experience, shaped the unequal oceanscapes of the present: mobility. </p>
<p>The conditions of decolonising, or – in places not yet decolonised – the ongoing conditions, determine the ability of Pacific peoples to move, visit and especially to work in wealthier societies. An American Samoan is entitled to visit and work in the US; a Samoan from independent Sāmoa is not. </p>
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Read more:
<a href="https://theconversation.com/nz-wants-more-seasonal-workers-but-pacific-nations-no-longer-want-to-be-the-outposts-that-grow-them-217790">NZ wants more seasonal workers – but Pacific nations no longer want to be the ‘outposts’ that ‘grow’ them</a>
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<p>At its closest point, Papua New Guinea is less than four kilometres from its former colonial ruler, Australia; but it is separated not just by a small gap of water, but a border of regulation and immigration control. There are three times as many Samoans in Australia as Papua New Guineans, and most of the Samoans have come via New Zealand – further away, but administratively much closer, and with free access on a New Zealand passport. </p>
<p>This means that both the pathways (which have typically been airways) to present economic conditions, as well as those to future economic opportunities, were chiefly forged under conditions of colonialism and empire. </p>
<p>The terms and conditions of formal decolonisation – what I think of as the decolonising bargain – was a bargain struck in profoundly unequal times and in unequal ways, where much of the power lay with former colonial rulers and international players. This decolonising bargain continues to structure mobility and other accommodations, as well as much else about present relationships, and it is rare that the Indigenous Pacific gets the better part of these deals.</p>
<h2>‘New blackbirds’</h2>
<p>These inequalities are evident at the national level for the Indigenous Pacific, but also in larger transnational and smaller, more local ways. The Pacific diaspora, so deeply conditioned by the decolonising bargain, has not mattered equally to Pacific nations recently. </p>
<p>In Melanesia, where the majority of Pacific people live, avenues of mobility are deeply restricted; in Polynesia and Micronesia, a majority of nations have some protected pathways to metropolitan nations. In smaller islands and nations these opportunities have seen mobility on remarkable scales; Niue is perhaps the most striking. Since the 1970s the number of Niueans in Niue has declined by around two-thirds, falling from over 5,000 to less than 2,000. The rest have “Gone Niu Silani”.</p>
<p>The new approach of Australia and New Zealand to exploiting Pacific labour has changed things: until the 2010s, to get Pacific peoples’ labour one had to allow them to be able to live, work and access education in at least semi-permanent ways. Since then, New Zealand, followed by Australia, has pursued a seasonal model that circumvents this, with Pacific people framed solely as workers, and forced home after a season. </p>
<p>This has been an economic boon for employers, but has had mixed, and increasingly deleterious, effects on Pacific peoples and their communities. The predicament of these Pacific people has even been likened to those recruited or kidnapped to work on sugar plantations over a century ago, in calling them the “New Blackbirds”.</p>
<p>The inequalities are unmistakable at the national scale: the independent Pacific nations are among the poorest nations in the world, but neighbours like the US, Australia and New Zealand are at the other end of the wealth scale. </p>
<p>Coarse indicators can tell the story because it is coarse: Australia has ten times the GDP per person of its former colony, Papua New Guinea, as does France compared with its territory Wallis and Futuna, and the US with its former colonies in the Marshall Islands and Federated States of Micronesia; New Zealand’s GDP per capita is seven-and-a-half times that of Sāmoa, which it governed until 1962. </p>
<p>Behind those numbers are powerful differences in healthcare, education and social provision, and they are reflected in almost every social statistic that is measured. As elsewhere in the former (or, as some might contend, currently) colonised world, the visible benefits of colonialism are not readily evident.</p>
<h2>Mobility and sovereignty</h2>
<p>Economic and educational opportunity sit at the heart of the Pacific diaspora, but there, too, the inequalities are unmistakable. In New Zealand, Australia, Hawai‘i and the US, in the blunt statistics of wellbeing and quality of life – health, education, housing – Indigenous peoples face worse outcomes than their non-Indigenous neighbours. </p>
<p>In each of these places, Indigenous Pacific migrants experience outcomes that more closely match their Indigenous neighbours than those of Pākehā/Papālagi/white populations. </p>
<p>Such an unassailable truth is this in New Zealand that not only are social statistics typically reported at different population levels, but a statistical category of non-Māori/non-Pacific is often used by government agencies. This is because Māori and Pacific outcomes are so much poorer than those of other New Zealanders, and the populations of both are so significant, that they distort both the analysis of these numbers and the numbers overall. </p>
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Read more:
<a href="https://theconversation.com/reaping-what-we-sow-cultural-ignorance-undermines-australias-recruitment-of-pacific-island-workers-197910">Reaping what we sow: cultural ignorance undermines Australia's recruitment of Pacific Island workers</a>
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<p>The same approach is taken in parts of Australia, too, and a similar impetus sat behind the disaggregation of a US population category and a recomposition (in censuses from 2010) of “Native Hawaiian and Other Pacific Islander”.</p>
<p>The Pacific nations and populations with higher standards of living – by traditional economic and social measures – are typically those with the closest relationship to former colonial powers, the least independence and the greatest political investment from their former governors. </p>
<p>The standards of living experienced in Hawai‘i, Guam and French Polynesia sit at another end of the spectrum from those of the Solomon Islands or Vanuatu. The trouble is, however, that these overall numbers hide domestic inequalities, particu¬larly in the Pacific settler colonies. </p>
<p>In those wealthier places we see locally the kind of powerful expressions of inequality that echo those of the wider Pacific: whether they are high rates of poverty and homelessness amongst Native Hawaiians in Hawai‘i or vastly differing standards of living between the majority of Kanaks and the Caldoche (French settlers) of New Caledonia. There are also other costs that these Indigenous Pacific people confront — paid in language, culture, well-being, identity, independence and sovereignty. </p>
<p>The transnational dimensions wrought by those Indigenous folks afforded mobility are profound. As Epeli Hau‘ofa so powerfully put it, these Pacific peoples can craft lives that resonate with the mobility of the ancestors. But the majority of Pacific peoples do not have access to transnational mobility. Few things are so absolute as lack of access to a passport, entry rights and an immigration visa. </p>
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Read more:
<a href="https://theconversation.com/with-independence-off-the-table-for-now-whats-next-for-new-caledonias-push-for-self-determination-204536">With independence off the table for now, what's next for New Caledonia's push for self-determination?</a>
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<p>Those of us in the Pacific diaspora who grew up dependent on these things know the force of them in our lives and the lives of our families. Some Pacific people are more mobile, assigned a citizenship or nationality that gives passports and paths to move that are denied – often strenuously – to others. </p>
<p>So it is that French Polynesians and Uveans may move around to other French territories, including France (and Europe); or Niueans to New Zealand; or Chamorros from Guam to the US. The opportunities can be life-changing, but so can the costs: the loss of sovereignty in most cases, but manifold other negative effects, from nuclear testing to military bases, from mining to profound assaults on and undermining of culture and language.</p>
<p>I have shared this thumbnail portrait of Pacific inequalities – geopolitical, national, transnational and domestic – not for its own sake, but because of the bearing these conditions have on our present understanding of the Pacific. These conditions shape Pacific research, scholarship and analysis, as they do those who are undertaking this work. They do so in powerful ways, and not all of them have attracted attention in the way they should.</p><img src="https://counter.theconversation.com/content/219483/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Damon Salesa does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>The author of a major new essay collection reflects on the shifting cultural and political realities in the Pacific, and why it remains an ‘unequal ocean’.Damon Salesa, Vice-Chancellor, Auckland University of TechnologyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2171472023-11-07T13:36:33Z2023-11-07T13:36:33ZAcapulco was built to withstand earthquakes, but not Hurricane Otis’ destructive winds – how building codes failed this resort city<figure><img src="https://images.theconversation.com/files/557873/original/file-20231106-267225-w11vn6.jpg?ixlib=rb-1.1.0&rect=0%2C16%2C3593%2C2246&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Acapulco's beachfront condo towers were devastated by Hurricane Otis.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/aerial-view-of-damages-caused-by-the-passage-of-hurricane-news-photo/1750791993">Rodrigo Oropeza/AFP via Getty Images</a></span></figcaption></figure><p>Acapulco wasn’t prepared when Hurricane Otis struck as a powerful Category 5 storm on Oct. 25, 2023. The short notice as the <a href="https://www.nesdis.noaa.gov/news/hurricane-otis-causes-catastrophic-damage-acapulco-mexico">storm rapidly intensified</a> over the Pacific Ocean wasn’t the only problem – the Mexican resort city’s buildings weren’t designed to handle anything close to Otis’ 165 mph winds.</p>
<p>While Acapulco’s oceanfront high-rises were built to withstand <a href="https://www.reuters.com/world/americas/strong-quake-rocks-mexicos-acapulco-damaging-airport-killing-one-2021-09-08/">the region’s powerful earthquakes</a>, they had a weakness. </p>
<p>Since powerful hurricanes are <a href="https://coast.noaa.gov/hurricanes">rare in Acapulco</a>, Mexico’s <a href="https://www.gob.mx/cms/uploads/attachment/file/247555/300617_EvaluacionEstructuras_02-Viento.pdf">building codes didn’t require</a> that their exterior materials be able to hold up to extreme winds. In fact, those materials were often kept light to help meet earthquake building standards.</p>
<p>Otis’ powerful winds ripped off exterior cladding and shattered windows, exposing bedrooms and offices to the wind and rain. The storm <a href="https://www.pbs.org/newshour/world/death-toll-from-hurricane-otis-hits-48-with-36-missing-as-search-and-recovery-continues">took dozens of lives</a> and caused <a href="https://www.reinsurancene.ws/corelogic-pegs-hurricane-otis-insurable-loss-at-10bn-to-15bn/">billions of dollars in damage</a>.</p>
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<img alt="A large glass tower with sloping sides, like a sliced egg, reflects the sunrise with the Pacific Ocean looking placid in the background." src="https://images.theconversation.com/files/557814/original/file-20231106-17-xzhpml.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/557814/original/file-20231106-17-xzhpml.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=397&fit=crop&dpr=1 600w, https://images.theconversation.com/files/557814/original/file-20231106-17-xzhpml.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=397&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/557814/original/file-20231106-17-xzhpml.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=397&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/557814/original/file-20231106-17-xzhpml.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=498&fit=crop&dpr=1 754w, https://images.theconversation.com/files/557814/original/file-20231106-17-xzhpml.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=498&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/557814/original/file-20231106-17-xzhpml.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=498&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">A US$130 million luxury condo building on the beach in Acapulco before Hurricane Otis struck on Oct. 25, 2023.</span>
<span class="attribution"><span class="source">Hamid Arabzadeh, PhD., P.Eng.</span></span>
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<img alt="A stormy sky shows through the floors that were once apartments." src="https://images.theconversation.com/files/557815/original/file-20231106-19-vbqly2.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/557815/original/file-20231106-19-vbqly2.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/557815/original/file-20231106-19-vbqly2.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/557815/original/file-20231106-19-vbqly2.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/557815/original/file-20231106-19-vbqly2.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/557815/original/file-20231106-19-vbqly2.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/557815/original/file-20231106-19-vbqly2.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">The same Acapulco condo tower after Hurricane Otis.</span>
<span class="attribution"><span class="source">Hamid Arabzadeh, PhD., P.Eng.</span></span>
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<p>I have worked on engineering strategies to enhance disaster resilience for over three decades and recently wrote a book, “<a href="https://rowman.com/ISBN/9781633888234/The-Blessings-of-Disaster-The-Lessons-That-Catastrophes-Teach-Us-and-Why-Our-Future-Depends-on-It">The Blessings of Disaster</a>,” about the gambles humans take with disaster risk and how to increase resilience. Otis provided a powerful example of one such gamble that exists when building codes rely on probabilities that certain hazards will occur based on recorded history, rather than considering the severe consequences of storms that can devastate entire cities.</p>
<h2>The fatal flaw in building codes</h2>
<p>Building codes typically provide “<a href="https://asce7hazardtool.online/">probabilistic-based” maps</a> that specify wind speeds that engineers must consider when designing buildings. </p>
<p>The problem with that approach lies in the fact that “probabilities” are simply the odds that extreme events of a certain size will occur in the future, mostly calculated based on past occurrences. Some models may include additional considerations, but these are still typically anchored in known experience. </p>
<p>This is all good science. Nobody argues with that. It allows engineers to design structures in accordance with a consensus on what are deemed acceptable <a href="https://doi.org/10.5194/nhess-19-1347-2019">return periods</a> for various hazards, referring to the likelihood of those disasters occurring. Return periods are a somewhat arbitrary assessment of what is a reasonable balance between minimizing risk and keeping building costs reasonable.</p>
<p>However, <a href="https://www.structuremag.org/?p=13360">probabilistic maps</a> only capture the odds of the hazard occurring. A <a href="https://hazards.atcouncil.org/">probabilistic map</a> might specify a wind speed to consider for design, irrespective of whether that given location is a small town with a few hotels or a megapolis with high-rises and complex urban infrastructure. In other words, probabilistic maps do not consider the consequences when an extreme hazard exceeds the specified value and “all hell breaks loose.”</p>
<h2>How probability left Acapulco exposed</h2>
<p>According to the Mexican building code, hotels, condos and other commercial and office buildings in Acapulco must be <a href="https://www.gob.mx/cms/uploads/attachment/file/247555/300617_EvaluacionEstructuras_02-Viento.pdf">designed to resist 88 mph winds</a>, corresponding to the strongest wind likely to occur on average once every 50 years there. That’s a Category 1 storm.</p>
<p>A 200-year return period for wind is used for essential facilities, such as hospital and school buildings, <a href="https://www.gob.mx/cms/uploads/attachment/file/247555/300617_EvaluacionEstructuras_02-Viento.pdf">corresponding to 118 mph winds</a>. But over a building’s life span of, say, 50 years, that still leaves a 22% chance that winds exceeding 118 mph will occur (yes, the world of statistics is that sneaky). </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/557871/original/file-20231106-15-ffcd7l.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A map of the Mexico area with lots of storm tracks offshore and a few crossing land in the southern part of the country." src="https://images.theconversation.com/files/557871/original/file-20231106-15-ffcd7l.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/557871/original/file-20231106-15-ffcd7l.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=457&fit=crop&dpr=1 600w, https://images.theconversation.com/files/557871/original/file-20231106-15-ffcd7l.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=457&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/557871/original/file-20231106-15-ffcd7l.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=457&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/557871/original/file-20231106-15-ffcd7l.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=575&fit=crop&dpr=1 754w, https://images.theconversation.com/files/557871/original/file-20231106-15-ffcd7l.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=575&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/557871/original/file-20231106-15-ffcd7l.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=575&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Mexico’s hurricane history in storm tracks.</span>
<span class="attribution"><a class="source" href="https://coast.noaa.gov/hurricanes/#map">NOAA</a></span>
</figcaption>
</figure>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/557869/original/file-20231106-19-jxgqql.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A map of the Acapulco area with lots of storm tracks offshore and a few crossing land." src="https://images.theconversation.com/files/557869/original/file-20231106-19-jxgqql.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/557869/original/file-20231106-19-jxgqql.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=427&fit=crop&dpr=1 600w, https://images.theconversation.com/files/557869/original/file-20231106-19-jxgqql.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=427&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/557869/original/file-20231106-19-jxgqql.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=427&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/557869/original/file-20231106-19-jxgqql.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=537&fit=crop&dpr=1 754w, https://images.theconversation.com/files/557869/original/file-20231106-19-jxgqql.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=537&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/557869/original/file-20231106-19-jxgqql.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=537&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A century of hurricane storm tracks near Acapulco show several offshore storms that brought strong winds and rain to the city, but few direct landfalls. Acapulco Bay is in the center of the map on the coast. Red, pink and purple lines are categories 3, 4 and 5, respectively.</span>
<span class="attribution"><a class="source" href="https://coast.noaa.gov/hurricanes/#map">NOAA</a></span>
</figcaption>
</figure>
<p>The probability wind maps for both return periods show Acapulco experiences lower average wind speeds than much of the 400 miles of Mexican coast north of the city. Yet, Acapulco is a major city, with a metropolitan population of over 1 million. It also has <a href="https://skyscraperpage.com/cities/?cityID=586&offset=100&statusID=1">more than 50 buildings</a> taller than 20 stories, according to the SkyscraperPage, a database of skyscrapers, and it is the only city with buildings that tall along that stretch of the Pacific coast.</p>
<p>Designing for a 50-year return period in this case is questionable, as it implies a near 100% chance of encountering wind exceeding this design value for a building with a 50-year life span or greater. </p>
<h2>Florida faces similiar challenges</h2>
<p>The shortcomings of probabilistic-based maps that specify wind speeds have also been observed in the United States. For example, new buildings along most of Florida’s coast must be able to <a href="https://www.flrules.org/gateway/readRefFile.asp?refId=13160&filename=Florida_Building_Code_7thEdition_1609_3_Tables.pdf">resist 140 mph winds</a> or greater, but there are a few exceptions. One is the Big Bend area where <a href="https://www.tampabay.com/hurricane/2023/09/02/map-idalia-flooding-big-bend-surge/">Hurricane Idalia made landfall</a> in 2023. Its design wind speed is about 120 mph instead.</p>
<p>A <a href="https://codes.iccsafe.org/content/FLBC2023P1/chapter-16-structural-design#FLBC2023P1_Ch16_Sec1609">2023 update to the Florida Building Code</a> raised the minimum wind speed to approximately 140 mph in Mexico Beach, the Panhandle town that was <a href="https://mexicobeachfl.gov/uploads/2022/06/Wind-load-Ordinance-21919.pdf">devastated by Hurricane Michael</a> in 2018. The Big Bend exception may be the next one to be eliminated.</p>
<h2>Acapulco’s earthquake design weakness</h2>
<p>A saving grace for Acapulco is that it is located in one of <a href="https://mexicodailypost.com/2021/04/19/earthquake-map-30-of-mexico-under-high-seismic-risk/">Mexico’s most active seismic risk zones</a> – for example, a <a href="https://www.nytimes.com/live/2021/09/07/world/mexico-earthquake">magnitude 7 earthquake struck nearby in 2021</a>. As a result, the lateral-load-resisting structural systems in tall buildings there are designed to resist seismic forces that are generally larger than hurricane forces.</p>
<p>However, a drawback is that the larger the mass of a building, <a href="https://www.wbdg.org/resources/seismic-design-principles">the larger the seismic forces</a> the building must be designed to resist. Consequently, light materials were typically used for the cladding – the exterior surface of the building that protects it against the weather – because that translates into lower seismic forces. This light cladding was not able to withstand hurricane-force winds.</p>
<p>Had the cladding not failed, the full wind forces would have been transferred to the structural system, and the buildings would have survived with little or no damage.</p>
<h2>A ‘good engineering approach’ to hazards</h2>
<p>A better building code could go one step beyond “good science” probabilistic maps and adopt a “<a href="https://michelbruneau.com/TheBlessingsOfDisaster.htm">good engineering approach</a>” by taking stock of the consequences of extreme events occurring, not just the odds that they will.</p>
<p>In Florida, the incremental cost of designing for wind speeds of 140 mph rather than 120 mph is marginal compared to total building cost, given that cladding able to resist more than 140 mph is already used in nearly all of the state. In Acapulco, with the spine of buildings already able to resist earthquake forces much larger than hurricane forces, designing cladding that can withstand stronger hurricane-level forces is likely to be an even smaller percentage of total project cost.</p>
<p>Someday, the way that design codes deal with extreme events such as hurricanes, not only in Mexico, will hopefully evolve to more broadly account for what is at risk at the urban scale. Unfortunately, as I explain in “<a href="https://michelbruneau.com/TheBlessingsOfDisaster.htm">The Blessings of Disaster</a>,” we will see more extreme disasters before society truly becomes disaster resilient.</p><img src="https://counter.theconversation.com/content/217147/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Michel Bruneau 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>The best science is not always the best engineering when it comes to building codes. It’s also a problem across the US, as an engineer who works on disaster resilience explains.Michel Bruneau, Professor of Engineering, University at BuffaloLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2123082023-10-17T15:29:28Z2023-10-17T15:29:28ZHow animal traits have shaped the journey of species across the globe<p>The devastating <a href="https://www.ngdc.noaa.gov/hazel/view/hazards/tsunami/event-more-info/5413">tsunami</a> that hit Japan in March 2011 set off a series of events which have long fascinated scientists like me. It was so powerful that it caused 5 million tonnes of debris to <a href="https://marinedebris.noaa.gov/japan-tsunami-marine-debris/monitoring-tsunami-debris-north-american-shorelines">wash</a> into the Pacific – 1.5 million tonnes remained afloat and started drifting with the currents. </p>
<p>One year later, and half a world away, debris began washing ashore on the west coast of North America. More than 280 Japanese coastal species such as mussels, barnacles and even some species of fish, had <a href="https://www.science.org/doi/full/10.1126/science.aao1498?casa_token=YwHfCNElf14AAAAA:zJj4eY3uUm2_m4ZH5YzIO6ecvSWdVa_53yZk0ycnxm1Ga3bPLTl5Z6hCbUhvsmA4d0KSPHFPKz84nQ">hitched a ride</a> on the debris and made an incredible journey across the ocean. These species were still alive and had the potential to establish new populations. </p>
<p>How animals cross major barriers, such as oceans and mountain ranges, to shape Earth’s biodiversity is an intriguing topic. And a new <a href="https://www.nature.com/articles/s41559-023-02150-5">study</a> by my collaborators and I has shed light on this process, revealing how animal characteristics such as body size and life history can influence their spread across the globe.</p>
<p>We know that such dispersal events occur in terrestrial species as well. For instance, at least 15 green iguanas <a href="https://www.nature.com/articles/26886">journeyed</a> more than 200km (124 miles) from Guadeloupe to Anguilla in the Caribbean in 1995. They arrived on a mat of logs and trees (likely uprooted through a hurricane), some of which were more than 9 metres (20 feet) long. </p>
<h2>The role of animal characteristics in dispersal</h2>
<p>When animals move across major barriers it can have a big impact on both the new and old locations. For example, an invasive species can arrive in a new area and compete with native species for resources. However, those consequences can be even greater over longer periods of time.</p>
<p>The movement of monkeys from Africa to South America around 35 million years ago led to the evolution of more than 90 species of <a href="https://www.annualreviews.org/doi/abs/10.1146/annurev-anthro-102116-041510?casa_token=CZtEoQ5Z9bMAAAAA%3AX9JrgVyGxxegDXgVTUPNHZboMldBec1egagn5S4pLwx4yudreF4L6Q6zG4jUeB9tMxJEIy4q67iX&journalCode=anthro">New World monkeys</a>, including tamarins, capuchins and spider monkeys. And a few chameleons rafting on vegetation from Africa to Madagascar is why we find half of all living <a href="https://royalsocietypublishing.org/doi/10.1098/rspb.2013.0184">chameleon</a> species there today.</p>
<p>These events were long thought to be determined by chance – the coincidence of some chameleons sitting on the right tree at the right time. However, <a href="https://www.jstor.org/stable/pdf/24529638.pdf?casa_token=NyxiUsFXod0AAAAA:9aBvrCPO0om98AjWOfs482QWf5eQxRUwKt95p4S3trPy1CQ2CM4K0AJeMBtsNKwKST8ILswcwdjQBRq8ZpdR5-3KL3gOn9uYZHOjzDdPyTm4R3Dom1o">some scientists</a> have suggested there might be more to it. They hypothesised there could be more general patterns in the animals that reach their destination successfully, related to certain characteristics.</p>
<p>Could body size affect how far a species can travel? Animals with more fat reserves may be able to travel longer distances. Or could it be how a species reproduces and survives? For example, animals that lay many eggs or mature early may be more likely to establish a new population in a new place.</p>
<p>But despite a vigorous theoretical debate, the options to test these hypotheses were limited because such dispersal events are rare. Also, the right statistical tools were not available until recently.</p>
<p>Thanks to the recent development of new <a href="https://academic.oup.com/sysbio/article/69/1/61/5490843">biogeographical models</a> and the great availability of data, we can now try to answer questions about how tetrapod species (amphibians, reptiles, birds and mammals) have moved around the globe over the past 300 million years and whether successful species share any common characteristics.</p>
<p>These models allow us to estimate the movements of species’ ancestors while also considering their characteristics. We used these models to study 7,009 species belonging to 56 groups of tetrapods.</p>
<h2>What we found</h2>
<p>For 91% of the animal groups we studied, models that included species characteristics were better supported than models that didn’t. This means that body size and life history are closely linked to how successful a species is at moving to and establishing itself in a new location.</p>
<p>Animals with large bodies and fast life histories (breeding early and often, like water voles) generally dispersed more successfully, as expected. However, there were some exceptions to this rule. In some groups, smaller animals or animals with average traits had higher dispersal rates.</p>
<p>For example, small hummingbirds dispersed better than larger ones, and poison dart frogs with intermediate life histories dispersed better than those with very fast or very slow life histories.</p>
<p>We investigated this variation further and found that the relationship between body size and movement depended on the average size and life history of the group. Our results show that the links between characteristics and dispersal success depend on both body size and life history, and that these cannot be considered separately. </p>
<p>Groups in which small size was an advantage were often already made up of small species (making the dispersal-prone species even smaller), and these species also had fast life histories. We found this to be true for the rodent families <a href="https://www.britannica.com/animal/Muridae"><em>Muridae</em></a> and <a href="https://nhpbs.org/wild/cricetidae.asp"><em>Cricetidae</em></a>. </p>
<p>But groups in which dispersers had intermediate body sizes generally had slow life histories (meaning they had low reproductive output but long lifespans). This means the combination of small body size and slow life history is very unlikely to be an advantage for dispersal across major barriers such as oceans.</p>
<h2>It’s not just chance</h2>
<p>It is amazing to think that rare dispersal events, which can lead to the rise of many new species, are not completely random. Instead, the intrinsic characteristics of species can shape the histories of entire groups of animals, even though chance still may play an important role.</p>
<p>At the same time, two of the most important <a href="https://zenodo.org/record/3553579">environmental challenges</a> of our time are related to movement across major barriers: biological invasions and species’ responses to climate change. On a planet facing rapid changes, understanding how animals move across barriers is therefore crucial.</p><img src="https://counter.theconversation.com/content/212308/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>While working on this study, Sarah-Sophie Weil was affiliated with Université Grenoble Alpes (France) and Swansea University (Wales, UK) who supported her through Initiative d’excellence (IDEX) International Strategic Partnership and Swansea University Strategic Partner Research (SUSPR) scholarships.</span></em></p>New research looks at how different species have managed to cross geographic barriers throughout history and whether their individual traits played a crucial role in these journeys.Sarah-Sophie Weil, PhD candidate, Swansea UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2153952023-10-12T12:30:45Z2023-10-12T12:30:45ZWhat is a strong El Niño? Meteorologists anticipate a big impact in winter 2023-2024, but the forecasts don’t all agree<figure><img src="https://images.theconversation.com/files/553361/original/file-20231011-29-363wak.png?ixlib=rb-1.1.0&rect=32%2C873%2C3211%2C2058&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The El Niño pattern stands out in the warm sea surface temperature anomalies in the Pacific in 2023</span> <span class="attribution"><a class="source" href="https://www.climate.gov/maps-data/data-snapshots/data-source/sst-enso-region-monthly-difference-average">NOAA Climate.gov</a></span></figcaption></figure><p><em>Meteorologists have been talking for weeks about <a href="https://www.accuweather.com/en/winter-weather/us-winter-forecast-for-the-2023-2024-season/1583853">a snowy season ahead</a> in the southern Rockies and the Sierra Nevada. They anticipate <a href="https://www.powder.com/trending-news/el-nino-huge-snow-east">more storms</a> in the U.S. South and Northeast, and warmer, drier conditions across the already dry Pacific Northwest and the upper Midwest.</em></p>
<p><em>One phrase comes up repeatedly with these projections: <a href="https://www.wcpo.com/weather/weather-101/a-strong-el-nino-expected-this-winter-heres-what-that-means-for-our-weather">a strong El Niño</a> is coming.</em></p>
<p><em>It sounds ominous. But what does that actually mean? We asked <a href="https://scholar.google.com/citations?user=z7CXcXkAAAAJ&hl=en">Aaron Levine</a>, an atmospheric scientist at the University of Washington whose research focuses on El Niño.</em></p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/wVlfyhs64IY?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">NOAA explains in animations how El Niño forms.</span></figcaption>
</figure>
<h2>What is a strong El Niño?</h2>
<p>During a normal year, the warmest sea surface temperatures are in the western Pacific and the Indian Ocean, in what’s known as the <a href="https://doi.org/10.1186/s40562-016-0054-3">Indo-Western Pacific warm pool</a>.</p>
<p>But every few years, the trade winds that blow from east to west weaken, allowing that warm water to slosh eastward and <a href="https://www.pmel.noaa.gov/elnino/schematic-diagrams">pile up along the equator</a>. The warm water causes the air above it to warm and rise, fueling precipitation in the central Pacific and shifting atmospheric circulation patterns across the basin.</p>
<p>This pattern is <a href="https://www.pmel.noaa.gov/elnino/what-is-el-nino">known as El Niño</a>, and it can <a href="https://www.climate.gov/media/13628">affect weather around the world</a>.</p>
<figure class="align-center ">
<img alt="An animation shows how warm water builds up along the equator off South America. The box where temperatures are measured is south of Hawaii." src="https://images.theconversation.com/files/553048/original/file-20231010-23-c36xip.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/553048/original/file-20231010-23-c36xip.gif?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=272&fit=crop&dpr=1 600w, https://images.theconversation.com/files/553048/original/file-20231010-23-c36xip.gif?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=272&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/553048/original/file-20231010-23-c36xip.gif?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=272&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/553048/original/file-20231010-23-c36xip.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=342&fit=crop&dpr=1 754w, https://images.theconversation.com/files/553048/original/file-20231010-23-c36xip.gif?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=342&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/553048/original/file-20231010-23-c36xip.gif?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=342&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The box shows the Niño 3.4 region as El Niño begins to develop in the tropical Pacific, from January to June 2023.</span>
<span class="attribution"><a class="source" href="https://www.climate.gov/">NOAA Climate.gov</a></span>
</figcaption>
</figure>
<p>A strong El Niño, in the most basic definition, occurs once the average sea surface temperature in the equatorial Pacific is at least 1.5 degrees Celsius (2.7 Fahrenheit) warmer than normal. It’s measured in an imaginary box along the equator, roughly south of Hawaii, known as the <a href="https://svs.gsfc.nasa.gov/4695">Nino 3.4 Index</a>.</p>
<p>But El Niño is a coupled ocean-atmosphere phenomenon, and the atmosphere also plays a crucial role.</p>
<p>What has been surprising about this year’s El Niño – and still is – is that the atmosphere hasn’t responded as much as we would have expected based on the rising sea surface temperatures.</p>
<h2>Is that why El Niño didn’t affect the 2023 hurricane season the way forecasts expected?</h2>
<p>The 2023 Atlantic hurricane season is a good example. Forecasters often use El Niño as a predictor of <a href="https://www.weather.gov/ilx/swop-springtopics">wind shear</a>, which can tear apart Atlantic hurricanes. But with the atmosphere not responding to the warmer water right away, the impact on Atlantic hurricanes was lessened and it turned out to be a <a href="https://www.nytimes.com/article/tropical-storm-sean-hurricane.html">busy season</a>.</p>
<p><a href="https://doi.org/10.1175/JCLI-D-12-00097.1">The atmosphere is what transmits El Niño’s impact</a>. Heat from the warm ocean water causes the air above it to warm and rise, which fuels precipitation. That air sinks again over cooler water. </p>
<p>The rising and sinking creates giant loops in the atmosphere <a href="https://www.climate.gov/news-features/blogs/enso/walker-circulation-ensos-atmospheric-buddy">called the Walker Circulation</a>. When the warm pool’s water shifts eastward, that also shifts where the rising and sinking motions happen. The atmosphere reacts to this change like ripples in a pond when you throw a stone in. These ripples affect the jet stream, which steers weather patterns in the U.S.</p>
<p>This year, in comparison with other large El Niño events – such as <a href="https://www.climate.gov/news-features/blogs/enso/united-states-el-ni%C3%B1o-impacts-0">1982-83, 1997-98</a> and <a href="https://www.climate.gov/news-features/understanding-climate/2015-state-climate-el-ni%C3%B1o-came-saw-and-conquered">2015-16</a> – we’re not seeing the same change in where the precipitation is happening. It’s taking much longer to develop, and it’s not as strong.</p>
<p>Part of that, presumably, is related to the whole tropics being very, very warm. But <a href="https://doi.org/10.1029/2019GL086182">this is still an emerging field of research</a>.</p>
<p>How El Niño will change with global warming is a big and open question. El Niño <a href="https://www.climate.gov/news-features/understanding-climate/climate-variability-oceanic-nino-index">only happens every few years</a>, and there’s a fair amount of variability between events, so just getting a baseline is tough.</p>
<h2>What does a strong El Niño typically mean for US weather?</h2>
<p>During <a href="https://www.climate.gov/enso">a typical El Niño winter</a>, the U.S. South and Southwest are cooler and wetter, and the Northwest is warmer and drier. The upper Midwest tends to be drier, while the Northeast tends to be a little wetter. </p>
<p>The likelihood and the intensity generally scale with the strength of the El Niño event.</p>
<p>El Niño has traditionally been good for the mountain snowpack in California, which the state relies for a large percentage of its water. But it is often not so good for the Pacific Northwest snowpack.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/553424/original/file-20231012-15-3wfvdw.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two maps showing wetter, cooler weather in the Southeast and drier warmer air in the north during El Nino." src="https://images.theconversation.com/files/553424/original/file-20231012-15-3wfvdw.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/553424/original/file-20231012-15-3wfvdw.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=834&fit=crop&dpr=1 600w, https://images.theconversation.com/files/553424/original/file-20231012-15-3wfvdw.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=834&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/553424/original/file-20231012-15-3wfvdw.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=834&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/553424/original/file-20231012-15-3wfvdw.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1047&fit=crop&dpr=1 754w, https://images.theconversation.com/files/553424/original/file-20231012-15-3wfvdw.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1047&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/553424/original/file-20231012-15-3wfvdw.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1047&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 jet stream takes a very different path in a typical El Niño vs. La Niña winter weather pattern. But these patterns have a great deal of variability. Not every El Niño or La Niña year is the same.</span>
<span class="attribution"><a class="source" href="https://www.climate.gov/media/14484">NOAA Climate.gov</a></span>
</figcaption>
</figure>
<p>The <a href="https://www.climate.gov/news-features/featured-images/how-el-ni%C3%B1o-and-la-ni%C3%B1a-affect-winter-jet-stream-and-us-climate">jet stream plays a role</a> in that shift. When the polar jet stream is either displaced very far northward or southward, storms that would normally move through Washington or British Columbia are steered to California and Oregon instead.</p>
<h2>What do the forecasts show for the months ahead?</h2>
<p>Whether forecasters think a strong El Niño will develop depends on whose forecast model they trust.</p>
<p>This past spring, the <a href="https://www.weather.gov/media/climateservices/NWS%20Climate%20Forecast%20and%20Tools.pdf">dynamical forecast models</a> were <a href="https://iri.columbia.edu/our-expertise/climate/forecasts/enso/current/?enso_tab=enso-sst_table">already very confident</a> about the potential for a strong El Niño developing. These are big models that solve basic physics equations, starting with current oceanic and atmospheric conditions. </p>
<p>However, statistical models, which use statistical predictors of El Niño calculated from historical observations, were less certain.</p>
<p>Even in the <a href="https://iri.columbia.edu/our-expertise/climate/forecasts/enso/current/?enso_tab=enso-sst_table">most recent forecast model outlook</a>, the dynamical forecast models were predicting a stronger El Niño than the statistical models were.</p>
<p>If you go by just a sea surface temperature-based El Niño index, the forecast is for a fairly strong El Niño. </p>
<p>But the indices that incorporate the atmosphere are not responding in the same way. We’ve seen <a href="https://psl.noaa.gov/enso/enso.current.html">atmospheric anomalies</a> – as measured by cloud height monitored by satellites or sea-level pressure at monitoring stations – on and off in the Pacific since May and June, <a href="https://images.theconversation.com/files/553327/original/file-20231011-15-kprvx9.png">but not in a very robust fashion</a>. Even in September, they were nowhere near as large as they were in 1982, in terms of overall magnitude.</p>
<p>We’ll see if the atmosphere catches up by wintertime, when El Niño peaks.</p>
<h2>How long do El Niños last?</h2>
<p>Often during El Niño events – particularly strong El Niño events – the sea surface temperature anomalies collapse really quickly during the Northern Hemisphere spring. Almost all end in April or May.</p>
<p>One reason is that El Niño sows the seeds of its own demise. When El Niño happens, it <a href="https://doi.org/10.1175/1520-0469(1997)054%3C0811:AEORPF%3E2.0.CO;2">uses up that warm water</a> and the warm water volume shrinks. <a href="https://doi.org/10.1175/1520-0442(2000)013%3C3551:OOWWVC%3E2.0.CO;2">Eventually, it has eroded its fuel</a>.</p>
<p><iframe id="aOiS8" class="tc-infographic-datawrapper" src="https://datawrapper.dwcdn.net/aOiS8/14/" height="400px" width="100%" style="border: none" frameborder="0"></iframe></p>
<p>The surface can stay warm for a while, but once the heat from the subsurface is gone and the trade winds return, the El Niño event collapses. At the end of past El Niño events, the sea surface anomaly dropped very fast and we saw conditions typically switch to La Niña – El Niño’s cooler opposite.</p><img src="https://counter.theconversation.com/content/215395/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Aaron Levine receives funding from NOAA and has received funding in the past from the National Research Council. He is a member of the American Geophysical Union </span></em></p>An atmospheric scientist explains how El Niño works, this year’s oddities and why this phenomenon doesn’t last long.Aaron Levine, Atmospheric Research Scientist, CICOES, University of WashingtonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2121582023-08-25T12:21:39Z2023-08-25T12:21:39ZWhy Japan has started pumping water from Fukushima into the Pacific – and should we be concerned?<p>Japan’s decision to <a href="https://www.theguardian.com/environment/2023/aug/24/japan-begins-releasing-fukushima-wastewater-into-pacific-ocean">release water</a> from the Fukushima nuclear power plant has been greeted with horror by the <a href="https://www.theguardian.com/environment/2023/aug/24/they-wont-buy-it-fish-traders-anxious-after-fukushima-wastewater-release">local fishing industry</a> as well as China and <a href="https://www.theguardian.com/world/2023/jul/04/we-depend-on-our-beautiful-reefs-fukushima-water-release-plan-sparks-concern-across-pacific">several Pacific Island states</a>. China – which together with Hong Kong imports more than <a href="https://www.bbc.co.uk/news/world-asia-66613158">US$1.1bn (£866m) of seafood</a> from Japan every year – has <a href="http://www.customs.gov.cn/customs/302249/2480148/5274475/index.html">slapped a ban</a> on all seafood imports from Japan, citing health concerns.</p>
<p>Tokyo has asked for the ban to be lifted immediately. The Japanese prime minister, Fumio Kishida, <a href="https://english.kyodonews.net/news/2023/08/a92c9689bb62-japan-pm-asks-china-to-lift-seafood-import-ban-after-water-release.html?phrase=Park&words=">told reporters</a> on Thursday: “We strongly encourage discussion among experts based on scientific grounds.” Japan has <a href="https://www.euractiv.com/section/global-europe/news/japan-releases-fukushima-water-into-the-ocean-prompting-criticism-seafood-bans/">previously criticised China</a> for spreading “scientifically unfounded claims”.</p>
<p>Japan remains steadfast in its assurance that the water is safe. The <a href="https://www.nature.com/articles/d41586-023-02057-y">discharge process</a>, which will take 30 years, was approved by the International Atomic Energy Agency – the intergovernmental organisation that develops safety standards for managing radioactive waste. And seawater samples taken following the water’s release showed radioactivity levels <a href="https://www.theguardian.com/environment/2023/aug/25/fukushima-daiichi-nuclear-power-plant-china-wastewater-release">more than seven times lower</a> than the drinking water limit set by the World Health Organization.</p>
<p>Since the world’s highest authority on radioactive waste backs Japan’s plan, should we also dismiss the concerns raised by Pacific nations and local fishermen as merely irrational fear of radioactive materials?</p>
<h2>Contaminated water</h2>
<p>In 2011, a magnitude 9.0 earthquake off the north-eastern coast of Japan’s main island, Honshu, <a href="https://www.britannica.com/event/Japan-earthquake-and-tsunami-of-2011">triggered a tsunami</a> that devastated many coastal areas of the country. Tsunami waves knocked out the Fukushima nuclear power plant’s backup electricity supply and caused meltdowns in three of its reactors. The event is regarded as one of the worst nuclear accidents in history.</p>
<p>Since the accident, water has been used to cool the damaged reactors. But, as the reactor core contains numerous radioactive elements, including ruthenium, uranium, plutonium, strontium, caesium and tritium, the cooling water has become contaminated.</p>
<p>The tainted water is stored in more than 1,000 steel tanks at the power plant. It has been treated to remove most of the radioactive contaminants – but traces of the radioactive isotope tritium remain.</p>
<p>Removing tritium from the water is challenging. Tritium is a radioactive form of hydrogen that forms water molecules with properties similar to regular water. </p>
<p>It does decay over time to form helium (which is less harmful). But tritium has a half-life of slightly over 12 years. </p>
<p>This is relatively quick in comparison to other radioactive contaminants. But it will still take around 100 years for the radioactivity of the tritium within the tanks at Fukushima to drop below 1%. </p>
<p>To safely store the water that will continue to be contaminated over that time (some <a href="https://apnews.com/article/japan-fukushima-nuclear-radioactive-wastewater-release-fdaed86a7366f68c70eca0397b71b221">100 tonnes of water</a> each day), the plant’s operators will need to construct an additional 2,700 storage tanks. This may be impractical – storage space at Fukushima is fast running out.</p>
<h2>Should we be concerned?</h2>
<p>Studies have, in the past, explored the health effects of tritium exposure. However, much of this research has focused on organisms such as <a href="https://www.britannica.com/animal/zebra-fish">zebrafish</a> and <a href="https://www.britannica.com/animal/mussel">marine mussels</a>. <a href="https://doi.org/10.1002/etc.4650">Research</a> from France, for example, found that tritium – in the form of titrated water – led to DNA damage, altered muscle tissue and changed movement patterns in zebrafish larvae. </p>
<p>Interestingly, the zebrafish were exposed to tritium concentrations similar to those estimated to be in the storage tanks at Fukushima. But the tritium at Fukushima will be significantly diluted before its release, reaching levels almost a million times lower than those that caused health issues in zebrafish larvae.</p>
<p>Marine organisms within the discharge zone will experience consistent exposure to this low concentration over the next 30 years. We cannot definitively rule out potential repercussions from this on marine life. And, importantly, the findings from these studies cannot be universally applied to all animals. </p>
<p>It’s worth noting, however, that organisms can eliminate half of the tritium in their bodies through biological processes in <a href="https://academic.oup.com/jrr/article/62/4/557/6256015">less than two weeks</a> (known as the biological half-life).</p>
<figure class="align-center ">
<img alt="A zebrafish." src="https://images.theconversation.com/files/544582/original/file-20230824-15-pugylp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/544582/original/file-20230824-15-pugylp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/544582/original/file-20230824-15-pugylp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/544582/original/file-20230824-15-pugylp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/544582/original/file-20230824-15-pugylp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/544582/original/file-20230824-15-pugylp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/544582/original/file-20230824-15-pugylp.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">Evidence that tritium can cause negative health effects in marine organisms is restricted to laboratory experiments on animals like zebrafish.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/zebrafish-danio-rerio-planted-aquarium-718879114">NERYXCOM/Shutterstock</a></span>
</figcaption>
</figure>
<h2>But that’s not everything</h2>
<p>In theory, it’s also possible that the potential health issues linked to tritium could worsen due to the presence of other chemical contaminants. In China, researchers discovered that exposing zebrafish larvae to both tritium and genistein – a naturally occurring compound produced by some plants that is commonly found in water – led to <a href="https://doi.org/10.3389/fenvs.2022.1001504">reduced survival and hatching rates</a>.</p>
<p>The amount of tritium used in this study was over 3,000 times less than that used in the French study. But it still exceeded the levels being discharged into the Pacific Ocean from Fukushima by almost 250 times.</p>
<p>Yet it’s possible that other chemical contaminants present in the ocean near Japan or within the storage tanks could interact with tritium in a similar way, potentially offsetting the benefits of dilution.</p>
<p>Given that we lack precise knowledge of the exact chemical pollutants present in Fukushima’s water storage tanks and their potential combined effects with tritium, it could be unwise to casually brush aside the very real concerns raised by Pacific nations and fishermen.</p>
<hr>
<figure class="align-right ">
<img alt="Imagine weekly climate newsletter" src="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
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</figure>
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<hr><img src="https://counter.theconversation.com/content/212158/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Edmond Sanganyado receives funding from the Analytical Chemistry Trust Fund (ACSS 23/0012) and the Royal Society of Chemistry (R21-0850929337).</span></em></p>Japan’s much-criticised plan to release wastewater from Fukushima into the Pacific is underway – and many are concerned.Edmond Sanganyado, Assistant Professor in Environmental Forensics, Northumbria University, NewcastleLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2110072023-08-23T21:22:36Z2023-08-23T21:22:36ZCoral reefs: How climate change threatens the hidden diversity of marine ecosystems<figure><img src="https://images.theconversation.com/files/543317/original/file-20230817-23-tvw75n.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C3982%2C2976&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A healthy reef on Kiritimati (Christmas Island, Republic of Kiribati).</span> <span class="attribution"><span class="source">(Danielle Claar)</span>, <span class="license">Author provided</span></span></figcaption></figure><iframe style="width: 100%; height: 100px; border: none; position: relative; z-index: 1;" allowtransparency="" allow="clipboard-read; clipboard-write" src="https://narrations.ad-auris.com/widget/the-conversation-canada/coral-reefs-how-climate-change-threatens-the-hidden-diversity-of-aquatic-ecosystems" width="100%" height="400"></iframe>
<p>Like the heat waves on land we have all grown familiar with, <a href="https://doi.org/10.1146/annurev-marine-032720-095144">marine heat waves</a> are being <a href="https://doi.org/10.1038/s41586-018-0383-9">amplified by climate change</a>. These extreme warm water events have <a href="https://doi.org/10.1038/s41558-019-0412-1">ushered in some of the most catastrophic impacts</a> of climate change and are now a major threat to ocean life. </p>
<p>Coral reefs, which are <a href="https://doi.org/10.1017/9781009157964.001">home to a quarter of all life in the ocean, are the most vulnerable</a>.
This is a dire situation, given the vast number of people who <a href="https://doi.org/10.1016/j.rsma.2019.100699">depend on coral reefs</a> for their sustenance and livelihoods. </p>
<p>As climate change pushes corals beyond their limits, a key question is <a href="https://doi.org/10.1016/j.cub.2017.04.047">why different corals vary in their sensitivity</a> to warm waters. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/542485/original/file-20230813-167275-4irzrr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/542485/original/file-20230813-167275-4irzrr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/542485/original/file-20230813-167275-4irzrr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/542485/original/file-20230813-167275-4irzrr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/542485/original/file-20230813-167275-4irzrr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/542485/original/file-20230813-167275-4irzrr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/542485/original/file-20230813-167275-4irzrr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A reef on Kiritimati (Christmas Island) at the end of the 2015-16 marine heat wave where some Porites lobata colonies survived (yellow/tan colours), some were alive but bleached (white colonies), and some died along with the rest of the reef (red/purple/pink colours of turf algae covering dead colonies). (Danielle Claar), Author provided.</span>
</figcaption>
</figure>
<p>In our <a href="https://doi.org/10.1126/sciadv.adf0954">new study in <em>Science Advances</em></a>, we examined the genetics of hundreds of individual corals during the 2015-16 El Niño-driven heat wave. Our results suggest that heat waves have hidden impacts on the genetic composition of reef-building corals. Understanding this could help scientists bolster reef resilience to future heat waves. </p>
<h2>Pushing corals out of their comfort zones</h2>
<p>Corals are <a href="https://doi.org/10.1126/science.aan8048">highly adapted to the temperature</a> of their local waters, with temperatures even 1 C warmer than normal pushing them out of their comfort zone. </p>
<p>Unusually warm water <a href="https://doi.org/10.1146/annurev.ecolsys.34.011802.132417">disrupts the vital relationship</a> between stony corals (the reef-builders) and their symbiotic partners, microscopic algae that provide food to the corals. This causes coral bleaching, and in many cases mortality. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/is-the-great-barrier-reef-reviving-or-dying-heres-whats-happening-beyond-the-headlines-210558">Is the Great Barrier Reef reviving – or dying? Here's what's happening beyond the headlines</a>
</strong>
</em>
</p>
<hr>
<p>The tropical heat wave at our study site in the central Pacific Ocean, Kiritimati (Christmas Island), lasted for ten months, a world record. This led to extensive coral bleaching, presenting an opportunity to determine why some corals died and others survived. </p>
<h2>Cryptic diversity within a widespread coral species</h2>
<p>We focused on the widespread lobed coral (<em>Porites lobata</em>). This species is amongst the most heat-tolerant corals, and despite <a href="https://doi.org/10.1126/sciadv.abq5615">almost 90 per cent of all coral cover being lost</a> on Kiritimati, over half of lobed corals survived. </p>
<p>In fact, some <em>Porites</em> colonies didn’t bleach at all. </p>
<p>Why?</p>
<p>Using genomic tools, we identified three distinct types of <em>Porites lobata</em> on Kiritimati. These lineages, which may represent distinct species, are indistinguishable by eye but genetically different. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/542847/original/file-20230815-29-rh83z4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/542847/original/file-20230815-29-rh83z4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/542847/original/file-20230815-29-rh83z4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/542847/original/file-20230815-29-rh83z4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/542847/original/file-20230815-29-rh83z4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=504&fit=crop&dpr=1 754w, https://images.theconversation.com/files/542847/original/file-20230815-29-rh83z4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=504&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/542847/original/file-20230815-29-rh83z4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=504&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Two colonies of Porities growing side-by-side on Kiritimati (Christmas Island) during the 2015-16 marine heat wave. One colony appears healthy while the other is severely bleached. (Kieran Cox), Author provided.</span>
</figcaption>
</figure>
<p>Such biodiversity is known as <a href="https://doi.org/10.1186/jbiol60">“cryptic diversity” or “hidden diversity.”</a> Although cryptic diversity is widespread across corals, its ecological implications remain unclear. </p>
<h2>Marine heat waves threaten cryptic diversity</h2>
<p>We found that one genetic lineage of <em>Porites</em> was highly sensitive to the heat wave: only 15 per cent of its colonies survived compared to 50-60 per cent in the other lineages. Thus, even in a coral widely considered to be stress tolerant, heat waves can have hidden impacts, threatening diversity that is invisible to the naked eye.</p>
<hr>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/out-of-danger-because-the-un-said-so-hardly-the-barrier-reef-is-still-in-hot-water-210787">Out of danger because the UN said so? Hardly – the Barrier Reef is still in hot water</a>
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<p>If future marine heat waves continue to have similar effects, eventually sensitive genotypes like this one could be completely lost, reducing the genetic diversity of coral reefs. </p>
<p>Because interbreeding between cryptic lineages and species can offer a <a href="https://doi.org/10.1046/j.1365-294x.2001.01216.x">potential avenue for future adaptation</a>, losses of genetic diversity could make a bad problem even worse by limiting future adaptation to changing environments.</p>
<h2>A forced breakup</h2>
<p>So why did <em>Porites</em> lineages on Kiritimati differ in survival? </p>
<p>One hypothesis is that they house symbiotic partners with different heat sensitivities. Using metabarcoding, a technique that attempts to identify everything found living in the coral tissue, we identified which symbionts were partnered with which corals before, during and after the heat wave.</p>
<p>We found that the distinct <em>Porites</em> lineages had different partnerships before the heat wave. <em>Porites</em> species pass on their symbionts from <a href="https://doi.org/10.1111/j.1529-8817.2012.01220.x">one generation to the next</a> and so these relationships likely arose over many generations.</p>
<figure class="align-center ">
<img alt="two divers inspect a coral reef" src="https://images.theconversation.com/files/543319/original/file-20230817-29-myzq3d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/543319/original/file-20230817-29-myzq3d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/543319/original/file-20230817-29-myzq3d.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/543319/original/file-20230817-29-myzq3d.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/543319/original/file-20230817-29-myzq3d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/543319/original/file-20230817-29-myzq3d.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/543319/original/file-20230817-29-myzq3d.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">Danielle Claar and a team member sample a tracked surviving colony at the end of the heat wave on Kiritimati (Christmas Island).</span>
<span class="attribution"><span class="source">(Julia K. Baum), Author provided.</span></span>
</figcaption>
</figure>
<p>By the end of the heat wave, however, one of <em>Porites’</em> unique algal partners had been virtually eliminated. The survivors of all lineages had similar symbionts, suggesting specialized relationships between the partners had been lost under extreme temperatures. </p>
<p>Thus, not only was a cryptic coral lineage left teetering on the edge of local extinction, but its specialized symbiotic relationship had also been forcefully broken up.</p>
<h2>Implications for conserving coral reefs</h2>
<p>Due to climate change and other threats, we are currently experiencing a <a href="https://doi.org/10.1038/35002708">biodiversity crisis</a>. Our findings underscore that this crisis extends beyond what the eye can see.</p>
<p>Cryptic species often occupy <a href="https://doi.org/10.1111/1365-2664.12246">unique ecological niches and play specific roles within ecosystems</a>. Discovering these hidden differences can enhance our understanding of how ecosystems function. But worryingly, we may be losing this critical diversity before it is even discovered. </p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/through-the-magnifying-glass-how-cutting-edge-technology-is-helping-scientists-understand-baby-corals-210372">Through the magnifying glass: how cutting-edge technology is helping scientists understand baby corals</a>
</strong>
</em>
</p>
<hr>
<p>Continued study of cryptic diversity could prove essential to building climate resilient ecosystems. Using heat tolerant cryptic lineages in <a href="https://doi.org/10.3389/fmars.2020.00237">restoration approaches</a>, for example, could help make reefs more tolerant to future warming. </p>
<p>Ultimately, <a href="https://doi.org/10.1126/science.aaw6974">greenhouse gas emissions must be rapidly reduced to curb planetary warming</a>. While targeted efforts to bolster coral reefs against climate change may buy limited time, the current heat waves blanketing the world’s oceans underscore that the ocean is simply becoming too hot for corals and we need to act rapidly to mitigate the damage.</p><img src="https://counter.theconversation.com/content/211007/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Samuel Starko receives funding from the Forrest Research Foundation, The University of Western Australia, The Australian Research Council (ARC), and Revive & Restore.</span></em></p><p class="fine-print"><em><span>Julia K. Baum receives funding from the Natural Sciences and Engineering Research Council of Canada (NSERC), the U.S. National Science Foundation (NSF), the David and Lucile Packard Foundation, the Rufford Maurice Laing Foundation, the Canadian Foundation for Innovation, British Columbia Knowledge Development Fund, University of Victoria, The Pew Charitable Trusts, and the National Geographic Society.
</span></em></p>Exploring the often unseen, and poorly understood, nuances of diversity within coral reefs may prove essential for ensuring the long-term health of Earth’s oceans.Samuel Starko, Forrest Research Fellow, The University of Western AustraliaJulia K. Baum, Professor of Biology, University of VictoriaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2118522023-08-22T14:24:09Z2023-08-22T14:24:09ZRemote Pacific coral reef shows at least some ability to cope with ocean warming – new study<figure><img src="https://images.theconversation.com/files/543575/original/file-20230820-225972-21eyt4.jpeg?ixlib=rb-1.1.0&rect=0%2C13%2C1736%2C1101&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A healthy coral reef in Palau in the western Pacific Ocean.</span> <span class="attribution"><span class="source">Liam Lachs</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Unprecedented ocean temperatures are triggering mass coral bleaching events across the <a href="https://coralreefwatch.noaa.gov/satellite/bleachingoutlook_cfs/weekly_90.php">world</a>. This year, the world’s third largest barrier reef, in Florida, is already being <a href="https://twitter.com/AFP/status/1685299136764280833">hit hard</a>.</p>
<p>New research by my colleagues and I offers a glimmer of hope: coral reefs we studied in the Pacific appear to have increased their resistance to high ocean temperatures. But this can only improve their long-term futures if there is strong global action on reducing carbon emissions.</p>
<p>We know that corals will need to withstand rising ocean temperatures to survive under climate change. And we know reef-building corals are acutely sensitive to even small increases in temperature. What we don’t yet know is whether their “thermal tolerance” – essentially their ability to handle high temperatures – can keep pace with ocean warming.</p>
<p>In normal conditions, corals live in symbiosis with microscopic algae housed within their tissue. These algae give corals their <a href="https://theconversation.com/revealed-why-some-corals-are-more-colourful-than-others-36866">beautiful colours</a>, and provide them with food through photosynthesis, just like plants (corals are animals, don’t forget). </p>
<p>However, this relationship <a href="https://www.cell.com/current-biology/pdf/S0960-9822(20)31591-8.pdf">breaks down when it’s too hot</a>: the microalgae are expelled, leaving the corals stark white, or bleached, which usually leads to death. Extreme temperatures can even kill corals outright, bypassing the gradual bleaching process.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/543509/original/file-20230818-15-ee0qxl.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="bleached coral" src="https://images.theconversation.com/files/543509/original/file-20230818-15-ee0qxl.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/543509/original/file-20230818-15-ee0qxl.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/543509/original/file-20230818-15-ee0qxl.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/543509/original/file-20230818-15-ee0qxl.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/543509/original/file-20230818-15-ee0qxl.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=565&fit=crop&dpr=1 754w, https://images.theconversation.com/files/543509/original/file-20230818-15-ee0qxl.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=565&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/543509/original/file-20230818-15-ee0qxl.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=565&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Mass bleaching in the Maldives in 2016 which led to many corals dying.</span>
<span class="attribution"><a class="source" href="https://link.springer.com/chapter/10.1007/978-3-030-20389-4_13">Stephen Bergacker</a>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>In our new study published in <a href="https://doi.org/10.1038/s41467-023-40601-6">Nature Communications</a> on the coral reefs of Palau, a nation of more than 300 small islands in the western Pacific Ocean, we found that the tolerance of corals to warm conditions has likely increased over the past three decades.</p>
<h2>Testing thermal tolerance</h2>
<p>Palau experienced intense marine heatwaves in 1998, 2010 and 2017, but interestingly, each successive event led to less coral bleaching. Such a phenomenon has also been recorded in <a href="https://www.sciencedirect.com/science/article/pii/S0960982221014901">Australia’s Great Barrier Reef</a>, <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0033353">south-east Asia</a>, and <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0070443">French Polynesia</a>. </p>
<p>Is this evidence that coral communities are adapting to hotter temperatures? We set out to test whether thermal tolerance has likely increased for at least those reefs in Palau, and if so, how quickly. </p>
<p>Our international team of researchers designed a simulation study, drawing on 35 years of sea surface temperature data and historic observations of bleaching. We found that the thermal tolerance of the coral communities in Palau has likely increased at 0.1°C/decade. That’s slightly less than the increase in global temperatures (about <a href="https://www.climate.gov/news-features/understanding-climate/climate-change-global-temperature">0.18°C/decade</a>) but does suggest these coral reefs have an innate capacity for climate resilience.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/543578/original/file-20230820-153592-nwaj3l.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="scuba diver above coral reef" src="https://images.theconversation.com/files/543578/original/file-20230820-153592-nwaj3l.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/543578/original/file-20230820-153592-nwaj3l.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/543578/original/file-20230820-153592-nwaj3l.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/543578/original/file-20230820-153592-nwaj3l.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/543578/original/file-20230820-153592-nwaj3l.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=504&fit=crop&dpr=1 754w, https://images.theconversation.com/files/543578/original/file-20230820-153592-nwaj3l.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=504&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/543578/original/file-20230820-153592-nwaj3l.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=504&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Researcher conducting a 3D mapping survey of a coral reef in Palau.</span>
<span class="attribution"><span class="source">Eveline van der Steeg</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>How coral reefs are adapting to warmer oceans</h2>
<p>More work is needed to pin down exactly what has happened, but there are various mechanisms that could explain this. </p>
<p>One involves the turnover of species. There are hundreds of different coral species, each with a <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/j.1461-0248.2012.01861.x?casa_token=8vXhQAvJA0cAAAAA:6E3XAgHUbuzWIXTrFc3Cq6mCXOI1w7cG8RrgsUb0tLnrOfYZK2aMenY5wMlsBb7Cg_EbafteVgUyVn0">unique evolutionary history and life strategy</a>. Some, like branching <em>Acropora</em>, are fast-growing yet sensitive to temperature, while others, like massive <em>Porites</em>, are slow-growing but more stress tolerant. </p>
<p>Severe heatwaves can weed out the sensitive species, leaving the coral reef dominated by the tougher ones, which can compromise important ecological functions like reef growth and habitat provision for seafood species.</p>
<p>The second mechanism is genetic adaptation. Thermal tolerance is a complex trait that is likely <a href="https://www.frontiersin.org/articles/10.3389/fmars.2017.00434/full">influenced by thousands of genes</a>, but most corals only have some of these. Following Darwin’s theory of survival of the fittest, natural selection can choose the winners under climate change. Over multiple generations and many rounds of selection, thermal tolerance genes can become more prevalent, and thus increase the thermal tolerance of species populations.</p>
<p>The final explanation involves individual acclimatisation. Even within the lifetime of a single coral, its ability to survive thermal stress events can change. As the saying goes, “<a href="https://www.the-scientist.com/features/environmental-memory-how-corals-are-adjusting-to-warmer-waters-69640">what doesn’t kill you makes you stronger</a>”, and so, being exposed to low-level thermal stress can later improve chances of survival under high-level thermal stress.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/543589/original/file-20230821-229778-hhvlx0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Three photos of corals" src="https://images.theconversation.com/files/543589/original/file-20230821-229778-hhvlx0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/543589/original/file-20230821-229778-hhvlx0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/543589/original/file-20230821-229778-hhvlx0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/543589/original/file-20230821-229778-hhvlx0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/543589/original/file-20230821-229778-hhvlx0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/543589/original/file-20230821-229778-hhvlx0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/543589/original/file-20230821-229778-hhvlx0.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">a) Community of corals with high species diversity; b) two corals of the same species with contrasting bleaching susceptibility; c) the symbiotic microalgal community housed within coral tissues.</span>
<span class="attribution"><a class="source" href="https://www.oist.jp/image/coral-polyps-and-their-symbionts">Liam Lachs; Laurie Raymundo; OIST</a>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>To make things more complicated, all of these processes – species-turnover, genetic adaptation and acclimatisation – can also occur in the microalgae communities living within each coral. Scientists like me will need to disentangle the mechanisms that have driven potential shifts in thermal tolerance in Palau and elsewhere.</p>
<h2>What does the future hold?</h2>
<p>Can coral thermal tolerance continue increasing into the future? If so, then will it be fast enough to keep pace with ocean warming? Our study tackles these questions using high-resolution future temperature projections from 17 <a href="https://www.carbonbrief.org/qa-how-do-climate-models-work/">global climate models</a>.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/543593/original/file-20230821-25-dna4wg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="three graphs" src="https://images.theconversation.com/files/543593/original/file-20230821-25-dna4wg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/543593/original/file-20230821-25-dna4wg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=750&fit=crop&dpr=1 600w, https://images.theconversation.com/files/543593/original/file-20230821-25-dna4wg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=750&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/543593/original/file-20230821-25-dna4wg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=750&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/543593/original/file-20230821-25-dna4wg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=942&fit=crop&dpr=1 754w, https://images.theconversation.com/files/543593/original/file-20230821-25-dna4wg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=942&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/543593/original/file-20230821-25-dna4wg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=942&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Projections of coral bleaching in Palau: if the Paris Agreement is achieved, in a middle-of-the-road scenario, and a worst-case scenario. An increase in thermal tolerance (blue line) buys some time, but coral reefs will still struggle unless climate change is halted.</span>
<span class="attribution"><a class="source" href="https://doi.org/10.1038/s41467-023-40601-6">Lachs et al</a>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Our analysis reaffirms the scientific consensus, that ultimately the future of coral reefs depends on rapidly reducing carbon emissions. However, if coral thermal tolerance can continue rising, then bleaching could be avoided on some reefs, or at least delayed. </p>
<p><a href="https://doi.org/10.1038/s41467-023-40601-6">Our study</a> and <a href="https://doi.org/10.1029/2021GL094128">others</a> have identified reefs with some level of innate climate resilience. This might buy us some time, but securing a future for coral reefs still hinges on rapid climate action. As our oceans get hotter, fewer reefs will escape bleaching conditions. </p>
<p>There are promising conservation measures, restoration efforts and more experimental interventions such as <a href="https://theconversation.com/coral-meet-coral-how-selective-breeding-may-help-the-worlds-reefs-survive-ocean-heating-166412">selective breeding</a> to increase thermal tolerance. All of these might <a href="https://www.sciencedirect.com/science/article/pii/S0006320721001592">help corals persist into the future</a>, but reducing carbon emissions is ultimately the only sure bet.</p>
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<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">
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<p class="fine-print"><em><span>Liam Lachs receives funding from the Natural Environment Research Council's ONE Planet Doctoral Training Programme. </span></em></p>This may buy us time, but many reefs are still doomed without serious action on climate change.Liam Lachs, PhD Candidate in Climate Change Ecology and Evolution, Newcastle UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2118692023-08-18T21:50:54Z2023-08-18T21:50:54ZTropical Storm Hilary pounds Southern California with heavy rain, flash flooding<figure><img src="https://images.theconversation.com/files/543534/original/file-20230818-19-oy7ob6.jpg?ixlib=rb-1.1.0&rect=975%2C10%2C2274%2C1368&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Hurricane Hilary was a powerful Category 4 storm as it headed for Baja California on Aug. 18, 2023.</span> <span class="attribution"><a class="source" href="https://www.star.nesdis.noaa.gov/goes/">NOAA NESDIS</a></span></figcaption></figure><p><em>Tropical Storm Hilary <a href="https://apnews.com/article/hilary-tropical-storm-flooding-california-mexico-f89aeddeb62d55c935699ac81ca85f1d">made landfall</a> on Mexico’s Baja peninsula, and its damaging wind and heavy rainfall moved <a href="https://www.nhc.noaa.gov/text/WTUS86-KLOX.shtml">into Southern California</a> on <a href="https://www.nhc.noaa.gov/refresh/graphics_ep4+shtml/204813.shtml?cone#contents">Aug. 20, 2023</a>. For the <a href="https://twitter.com/NWSSanDiego/status/1692564593132933367">first time ever</a>, the National Hurricane Center had <a href="https://www.nhc.noaa.gov/archive/2023/ep09/ep092023.public.011.shtml?">issued a tropical storm watch</a> for large parts of Southern California. Forecasters warned of a “<a href="https://www.nhc.noaa.gov/archive/2023/ep09/ep092023.discus.014.shtml?">potentially historic</a> amount of rainfall,” and the governors of <a href="https://www.gov.ca.gov/2023/08/19/governor-newsom-proclaims-state-of-emergency-as-hurricane-hilary-approaches-california/">California</a> and <a href="https://carsonnow.org/story/08/20/2023/governor-lombardo-declares-state-emergency-across-nevada-due-hurricane-hilary">Nevada</a> declared states of emergency.</em></p>
<p><em>Hurricane scientist <a href="https://scholar.google.com/citations?user=5uEy_XoAAAAJ&hl=en">Nick Grondin</a> explained ahead of landfall why <a href="https://www.nhc.noaa.gov/archive/2023/HILARY.shtml?">the storm</a>, with help from El Niño and a heat dome over much of the country, could bring <a href="https://www.nhc.noaa.gov/archive/2023/ep09/ep092023.public.011.shtml?">flash flooding</a>, wind damage and mudslides to the region.</em></p>
<h2>How rare are tropical storms in the Southwest?</h2>
<p>California had only one confirmed tropical storm landfall in the past. It was in September 1939 and called <a href="https://www.sandiegouniontribune.com/news/150-years/sd-me-150-years-september-26-htmlstory.html">the Long Beach Tropical Storm</a>. It caused <a href="https://www.aoml.noaa.gov/hrd/Landsea/chenowethlandsea.pdf">about US$2 million dollars</a> in damage in the Los Angeles area – that would be about $44 million today. A <a href="https://doi.org/10.1175/BAMS-85-11-1689">hurricane in 1858</a> came close but didn’t make landfall, though its winds did significant damage to San Diego.</p>
<p>What the Southwest does see fairly regularly are the remnants of tropical cyclones, storms that continue on after a tropical cyclone loses its surface circulation. These remnant storms are <a href="https://doi.org/10.1175/2010MWR3389.1">more common</a> in the region than people might think. </p>
<p>Just last year, <a href="https://www.nhc.noaa.gov/data/tcr/EP122022_Kay.pdf">Hurricane Kay</a> took a similar track to the one Hurricane Hilary is on and brought significant rainfall to Southern California and Arizona. Famously, <a href="https://www.wpc.ncep.noaa.gov/tropical/rain/nora1997.html">Hurricane Nora in 1997</a> made landfall in Mexico’s Baja California and kept moving north, bringing tropical storm-force winds to California and widespread flooding that caused <a href="https://www.weather.gov/media/hazstat/sum97.pdf">hundreds of millions of dollars in damage</a>, particularly to fruit trees <a href="https://www.weather.gov/media/hazstat/sum97.pdf">and agriculture</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/543551/original/file-20230819-19-dbyiqs.gif?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A map shows rainfall forecast across much of Southern California and into Arizona and Nevada." src="https://images.theconversation.com/files/543551/original/file-20230819-19-dbyiqs.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/543551/original/file-20230819-19-dbyiqs.gif?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=482&fit=crop&dpr=1 600w, https://images.theconversation.com/files/543551/original/file-20230819-19-dbyiqs.gif?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=482&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/543551/original/file-20230819-19-dbyiqs.gif?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=482&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/543551/original/file-20230819-19-dbyiqs.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=605&fit=crop&dpr=1 754w, https://images.theconversation.com/files/543551/original/file-20230819-19-dbyiqs.gif?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=605&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/543551/original/file-20230819-19-dbyiqs.gif?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=605&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 National Hurricane Center’s three-day rainfall forecast issued Aug. 19, 2023, shows rainfall totals that are well above what some areas typically receive in a year.</span>
<span class="attribution"><a class="source" href="https://www.nhc.noaa.gov/refresh/graphics_ep4+shtml/175024.shtml?rainqpf#contents">National Hurricane Center</a></span>
</figcaption>
</figure>
<p>A study led by atmospheric scientist <a href="https://scholar.google.com.au/citations?user=rHHmqXgAAAAJ&hl=en">Elizabeth Ritchie</a> in 2011 found that, on average, <a href="https://doi.org/10.1175/2010MWR3389.1">about 3.1 remnant systems</a> from tropical cyclones affected the U.S. Southwest each year from 1992 to 2005. That’s a short record, but it gives you an idea of the frequency.</p>
<p>Typically, the remnants of tropical cyclones don’t go beyond California, Nevada and Arizona, <a href="https://www.wpc.ncep.noaa.gov/tropical/rain/tcrainfall.html">though it wouldn’t be unprecedented</a>. In this case, forecasters expect the effects to extend far north. The National Hurricane Center on Aug. 18 projected at least a <a href="https://www.nhc.noaa.gov/refresh/graphics_ep4+shtml/175024.shtml?ero#contents">moderate risk of flooding</a> across large parts of Southern California, southern Nevada and far-western Arizona, and a high risk of flooding for regions east of San Diego.</p>
<h2>What’s making this storm so unusual?</h2>
<p>One influence is the <a href="https://theconversation.com/el-nino-is-back-thats-good-news-or-bad-news-depending-on-where-you-live-205974">El Niño climate pattern</a> this year, which is showing signs of strengthening in the Pacific. Another, which might be less intuitive, is the <a href="https://www.washingtonpost.com/weather/2023/08/17/heat-wave-texas-excessive-heat-warning/">heat dome over much of the U.S.</a></p>
<p>During El Niño, the tropical Pacific is warmer than normal, and both the eastern and central Pacific tend to be more active with storms, as we saw in 2015 and 1997. Generally, hurricanes need <a href="https://oceanexplorer.noaa.gov/facts/hurricanes.html">at least 80 degrees</a> Fahrenheit (27 degrees Celsius) to maintain their intensity. Normally, the waters off Southern California <a href="https://www.ncei.noaa.gov/access/coastal-water-temperature-guide/spac.html">are much cooler</a>. But with the high initial intensity of Hurricane Hilary over warm water to the south, and the fact that the storm is moving fast, forecasters think it might be able to survive the cooler water.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1691594717115335132"}"></div></p>
<p>The influence of the heat dome is interesting. Meteorology researcher <a href="https://scholar.google.com/citations?user=16yNCisAAAAJ&hl=en">Kimberly Wood</a> published a fantastic thread on X, formerly known as Twitter, describing the <a href="https://twitter.com/DrKimWood/status/1691956790144155962">large-scale pattern around similar storms</a> that have affected the southwestern United States. A common thread with these storms is the presence of a ridge, or high-pressure system, in the central U.S. When you have a high-pressure system like the heat dome covering much of the country, air is pushed down and warms significantly. Air around this ridge is moving clockwise. Meanwhile, a low-pressure system is over the Pacific Ocean with winds rotating counterclockwise. The result is that these <a href="https://twitter.com/WeatherProf/status/1691594717115335132">winds are likely to accelerate Hilary northward</a> into California.</p>
<p>Despite the rarity of tropical cyclones reaching California, numerical weather prediction models since the storm’s formation have generally shown Hilary likely to accelerate along the west coast of Baja California and push into Southern California.</p>
<h2>What are the risks?</h2>
<p>The threat of tropical storm-force winds led the National Hurricane Center to issue its <a href="https://twitter.com/NWSSanDiego/status/1692564593132933367">first-ever tropical storm watch</a> for Southern California on Aug. 18. However, water is almost always the primary concern with tropical storms. In California, that can mean flash flooding from extreme rainfall enhanced by mountains.</p>
<p>When a tropical storm plows up on a mountain, that can lead to more lifting, more condensation aloft and more rainfall than might otherwise be expected. It happened with <a href="https://www.nhc.noaa.gov/data/tcr/EP142018_Lane.pdf">Hurricane Lane in Hawaii</a> in 2018 and can also happen in other tropical cyclone-prone locations with significant orographic, or mountain, effects, such as the west coast of Mexico.</p>
<p>That can mean dangerous flash flooding from the runoff. It can also have a secondary hazard – mudslides, <a href="https://twitter.com/CAL_FIRE/status/1692596995330814311">including in areas recovering from wildfires</a>.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1692596995330814311"}"></div></p>
<p>In dry areas, heavy downpours can also trigger flash flooding. Forecasts showed Death Valley likely to get <a href="https://twitter.com/Climatologist49/status/1692550601677390298">more rain from the storm</a> than <a href="https://www.nps.gov/deva/planyourvisit/weather.htm">its average</a> for an entire year. Death Valley National Park warned of <a href="https://www.nps.gov/deva/planyourvisit/conditions.htm">flash flooding through Aug. 22</a> and closed its visitor centers and campgrounds. </p>
<p>Keep in mind this is still an evolving situation. Forecasts can change, and all it takes is one band of rain setting up in the right spot to cause significant flooding. Those in the path of Hilary should refer to their local weather offices for additional information. This would include local <a href="http://www.hurricanes.gov">National Weather Service</a> offices in the United States and <a href="https://smn.conagua.gob.mx/es/">Servicio Meteorológico Nacional</a> in Mexico.</p>
<p><em>This article, originally published Aug. 18, 2023, was updated with Tropical Storm Hilary making landfall.</em></p><img src="https://counter.theconversation.com/content/211869/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Nicholas Grondin 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>Forecasters warned of ‘potentially historic rainfall’ and ‘dangerous to locally catastrophic flooding.’ A hurricane scientist explains what El Niño, a heat dome and mountains have to do with the risk.Nicholas Grondin, Assistant Professor of Environmental Studies, University of TampaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2084122023-06-29T11:15:17Z2023-06-29T11:15:17ZEl Niño could push global warming past 1.5°C – but what is it and how does it affect the weather in Europe?<figure><img src="https://images.theconversation.com/files/534592/original/file-20230628-29-3vggu2.jpg?ixlib=rb-1.1.0&rect=27%2C0%2C3072%2C2046&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A natural weather event known as El Niño is underway in the Pacific Ocean.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/el-nino-san-diego-788564623">jon sullivan/Shutterstock</a></span></figcaption></figure><p>Scientists have warned that 2024 could mark the year when global warming <a href="https://www.bbc.co.uk/news/science-environment-65839060">exceeds 1.5°C above pre-industrial levels</a>. They attribute these predictions, at least in part, to the emergence of an El Niño event.</p>
<p>An El Niño <a href="https://www.climate.gov/news-features/blogs/june-2023-enso-update-el-ni%C3%B1o-here">is declared</a> when the sea surface temperature in large parts of the central or eastern equatorial regions of the Pacific Ocean warms significantly – sometimes by as much as 2°C. This additional heat in turn warms the atmosphere. During El Niño years, this warming contributes to a temporary rise in the global temperature by a fraction of a degree. </p>
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<p>El Niño primarily affects weather in the tropics. Intense downpours that would usually fall on parts of south-east Asia or eastern Australia instead fall on the west coast of South America. This change can cause major drought and <a href="https://www.pnas.org/doi/10.1073/pnas.1409822111">flooding</a> on different continents, affecting <a href="https://www.fao.org/el-nino/en/">food production</a> and even weather-dependent sports like <a href="https://rmets.onlinelibrary.wiley.com/doi/10.1002/wea.403">cricket</a>.</p>
<p>But changes to the weather in these regions can have knock-on effects all over the world. Even thousands of kilometres away in northern Europe, El Niño tends to cause colder and drier winter weather. </p>
<p>Yet many factors affect European weather, especially during winter. So care is needed when linking unusual weather events in Europe to El Niño.</p>
<figure class="align-center ">
<img alt="Storm clouds over the Andaman Sea." src="https://images.theconversation.com/files/534591/original/file-20230628-15-yriir7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/534591/original/file-20230628-15-yriir7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/534591/original/file-20230628-15-yriir7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/534591/original/file-20230628-15-yriir7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/534591/original/file-20230628-15-yriir7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/534591/original/file-20230628-15-yriir7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/534591/original/file-20230628-15-yriir7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Storm clouds over the Andaman Sea, Thailand.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/severe-storm-clouds-torrential-rain-shaft-1303569019">Ian Murdoch/Shutterstock</a></span>
</figcaption>
</figure>
<h2>What is El Niño?</h2>
<p>The Pacific Ocean spans over 13,000 kilometres from its eastern edge on the South American coast to its western margins near Indonesia. The sea surface temperature changes considerably over this vast distance. </p>
<p>Normally, the eastern edge of the Pacific Ocean is more than 5°C colder on average than the western Pacific. This is primarily due to the <a href="https://www.youtube.com/watch?v=WPA-KpldDVc">upwelling of cold water near South America</a>, a process in which colder water is pulled up from deeper down in the ocean.</p>
<p>However, this temperature contrast flattens or steepens every few years in a natural cycle called the <a href="https://www.climate.gov/news-features/blogs/enso/what-el-ni%C3%B1o%E2%80%93southern-oscillation-enso-nutshell">El Niño southern oscillation</a> (Enso). During this cycle, the strength of trade winds that blow westwards across the Pacific can strengthen or weaken, causing more or less cold water to upwell and flow along the equator. </p>
<p>We’re currently entering a period where the eastern Pacific will be warmer than it usually is – an El Niño event. Forecasts suggest that a part of the equatorial Pacific, regarded as a key indicator of Enso, has a <a href="https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/ensodisc.shtml">50% chance of warming by over 1.5°C</a> by the start of 2024.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/69N494UIlS8?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">How Pacific Ocean temperatures change during an El Niño event.</span></figcaption>
</figure>
<p>La Niña is the opposite phase of the cycle. It is instead characterised by cooler sea surface temperatures in these waters. This year brought an end to three successive La Niña years.</p>
<p>The western tropical Pacific region has some of the warmest ocean temperatures on Earth. Humid air tends to converge here, creating unstable conditions characterised by turbulent rising air known as <a href="https://www.metoffice.gov.uk/weather/learn-about/weather/how-weather-works/what-is-convection">convection</a> by meteorologists. The result of this is towering clouds and intense rainfall. </p>
<p>The region with the highest ocean temperature tends to experience the greatest amount of rainfall. As the warmest ocean temperatures shift eastward during El Niño, so too does the location of maximum cloud cover and rainfall.</p>
<p>Each El Niño event is different. Some mainly warm the eastern Pacific Ocean, such as the <a href="https://en.wikipedia.org/wiki/1997%E2%80%9398_El_Ni%C3%B1o_event">1997-98 event</a>. Others cause more warming in the central Pacific, <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2011GL048521">like in 2009-10</a>.</p>
<h2>How does it affect Europe’s climate?</h2>
<p>Towering clouds and intense rains in the western Pacific create atmospheric waves known as <a href="https://oceanservice.noaa.gov/facts/rossby-wave.html">Rossby waves</a>. These waves extend over thousands of kilometres and travel into and along the eastward-flowing <a href="https://www.metoffice.gov.uk/weather/learn-about/weather/types-of-weather/wind/what-is-the-jet-stream">jet streams</a> that encircle the planet’s mid-latitude regions. When the Rossby waves interact with the jet streams, they cause them to undulate.</p>
<p>As unsettled weather in the Pacific moves eastwards during an El Niño event, it influences the location of the peaks and troughs of these Rossby waves. This results in subtle changes in the positions of the jet streams. These alterations in the jet streams, which play a significant role in shaping weather patterns, can have notable <a href="https://www.climate.gov/news-features/featured-images/how-el-ni%C3%B1o-and-la-ni%C3%B1a-affect-winter-jet-stream-and-us-climate">effects on weather conditions</a> worldwide.</p>
<p>Depending on the specific movement of the jet stream in a particular area, the effect can either lead to warmer or cooler weather, despite El Niño warming the global climate as a whole. El Niño tends to slightly warm Europe in summer and <a href="https://www.metoffice.gov.uk/research/climate/seasonal-to-decadal/gpc-outlooks/el-nino-la-nina">slightly cool</a> northern Europe in winter.</p>
<h2>External noise</h2>
<p>However, a colder-than-average winter in Europe is not guaranteed during an El Niño event. Europe’s winter climate is <a href="https://www.metoffice.gov.uk/weather/learn-about/weather/seasons/winter/factors-that-influence-uk-winters">affected by various factors</a> beyond El Niño, including <a href="https://journals.ametsoc.org/view/journals/mwre/142/2/mwr-d-13-00104.1.xml?tab_body=abstract-display">conditions in the Atlantic</a>, the amount of Arctic sea ice and the state of the stratosphere 15-40km above us (which is <a href="https://journals.ametsoc.org/view/journals/clim/22/15/2009jcli2717.1.xml">itself affected by El Niño</a>). </p>
<p>For instance, the <a href="https://www.metoffice.gov.uk/weather/learn-about/weather/atmosphere/quasi-biennial-oscillation">quasi-biennial oscillation</a> – a regular reversal of winds that blow high above the equator – can alter wind patterns in the stratosphere. This can subsequently affect the position of the North Atlantic storm track, which influences Europe’s winter weather.</p>
<p>But even then, the underlying warming trend caused by climate change is making higher temperatures more probable in all seasons. Together, these other factors make any climatic signals from El Niño harder to detect and forecast. Caution must therefore be exercised before <a href="https://www.metoffice.gov.uk/research/climate/understanding-climate/attributing-extreme-weather-to-climate-change">attributing anomalies</a> in European winter weather to El Niño alone.</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">
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</figure>
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<p class="fine-print"><em><span>Manoj Joshi receives funding from the UK Natural Environment Research Council (NERC)</span></em></p>An El Niño weather-warming phase is underway in the Pacific – but what does this mean for the weather in Europe?Manoj Joshi, Professor of Climate Dynamics, University of East AngliaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2059742023-06-09T12:28:55Z2023-06-09T12:28:55ZEl Niño is back – that’s good news or bad news, depending on where you live<figure><img src="https://images.theconversation.com/files/531003/original/file-20230608-17-s154j9.png?ixlib=rb-1.1.0&rect=1183%2C300%2C2231%2C1465&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Warm water along the equator off South America signals an El Niño, like this one in 2016.</span> <span class="attribution"><a class="source" href="https://www.nesdis.noaa.gov/news/el-nino">NOAA</a></span></figcaption></figure><p>El Niño is <a href="https://www.climate.gov/news-features/blogs/june-2023-enso-update-el-ni%C3%B1o-here">officially here</a>, and while it’s still weak right now, federal forecasters expect this global disrupter of worldwide weather patterns to gradually strengthen. </p>
<p>That may sound ominous, but El Niño – Spanish for “the little boy” – is not malevolent, or even automatically bad.</p>
<p>Here’s what forecasters expect, and what it means for the U.S.</p>
<h2>What is El Niño?</h2>
<p>El Niño is a climate pattern that starts with warm water building up in the tropical Pacific west of South America. This happens every three to seven years or so. It might last <a href="https://images.theconversation.com/files/531150/original/file-20230609-686-qbp36v.png">a few months or a couple of years</a>.</p>
<p>Normally, the trade winds push warm water away from the coast there, allowing <a href="https://earthobservatory.nasa.gov/features/ElNino">cooler water to surface</a>. But <a href="https://oceanservice.noaa.gov/facts/ninonina.html">when the trade winds weaken</a>, water near the equator can heat up, and that can have all kinds of effects through what are known as teleconnections. The ocean is so vast – covering approximately one-third of the planet, or about 15 times the size of the U.S. – that those sloshings of warm water have knock-on effects around the globe.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/_Tuou_QcgxI?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">The National Oceanic and Atmospheric Administration explains teleconnections and the impact of El Niño.</span></figcaption>
</figure>
<p>That warming at the equator during El Niño leads to the warming of the stratosphere, starting about 6.2 miles (10 kilometers) above the surface. Scientists are still studying how exactly this teleconnection occurs. </p>
<p>At the same time, the lower tropical stratosphere cools.</p>
<p>That combination can shift the upper-level winds known as the jet stream, which blow from west to east. Altering the jet stream can affect all kinds of weather variables, from temperatures to storms and winds that can <a href="https://theconversation.com/2023-hurricane-forecast-get-ready-for-a-busy-pacific-storm-season-quieter-atlantic-than-recent-years-thanks-to-el-nino-204526">tear hurricanes apart</a>.</p>
<p>Basically, what happens in the Pacific doesn’t stay in the Pacific.</p>
<p><iframe id="aOiS8" class="tc-infographic-datawrapper" src="https://datawrapper.dwcdn.net/aOiS8/6/" height="400px" width="100%" style="border: none" frameborder="0"></iframe></p>
<h2>So, what does all that mean for you and me?</h2>
<p>With apologies to Charles Dickens, El Niño tends to create a tale of two regions: the best of times for some, and the worst of times for others.</p>
<p>On average, <a href="https://public.wmo.int/en/media/press-release/past-eight-years-confirmed-be-eight-warmest-record">El Niño years are warmer globally</a> than La Niña years – El Niño’s opposite. Globally, a strong El Niño can boost temperatures by about 0.7 degrees Fahrenheit (0.4 Celsius). But in North America, there is a lot of local variation. </p>
<p>El Niño years tend to be warmer across the northern part of the U.S. and in Canada, and the Pacific Northwest and Ohio Valley are often drier than usual in the winter and fall. The Southwest, on the other hand, tends to be <a href="https://oceanservice.noaa.gov/facts/ninonina.html">cooler and wetter than average</a>.</p>
<p>El Niño typically shifts the jet stream farther south, so it blows pretty much due west to east over the southern U.S. That shift tends to block moisture from the Gulf of Mexico, reducing the fuel for thunderstorms in the Southeast. La Niña, conversely, is associated with a more wavy and northward-shifted jet stream, which can enhance severe weather activity in the South and Southeast.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/530984/original/file-20230608-12369-joi210.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A map shows warmer, drier air over the northern U.S. and Canada; wetter conditions across the Southwest and dry in the Southeast. The jet stream shifts southward." src="https://images.theconversation.com/files/530984/original/file-20230608-12369-joi210.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/530984/original/file-20230608-12369-joi210.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/530984/original/file-20230608-12369-joi210.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/530984/original/file-20230608-12369-joi210.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/530984/original/file-20230608-12369-joi210.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/530984/original/file-20230608-12369-joi210.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/530984/original/file-20230608-12369-joi210.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">El Niño’s typical effects in winter.</span>
<span class="attribution"><a class="source" href="https://www.climate.gov/sites/default/files/2022-05/ElNino_winter_flat_Feb2016update_large_1.png">NOAA</a></span>
</figcaption>
</figure>
<p>El Niño also affects hurricanes, but in <a href="https://theconversation.com/2023-hurricane-forecast-get-ready-for-a-busy-pacific-storm-season-quieter-atlantic-than-recent-years-thanks-to-el-nino-204526">different ways in the Atlantic and Pacific</a>.</p>
<p>Over the Atlantic, El Niño tends to <a href="https://theconversation.com/atlantic-hurricane-season-2023-el-nino-and-extreme-atlantic-ocean-heat-are-about-to-clash-204670">increase wind shear</a> – the change in wind speed with height in the atmosphere – which can tear apart hurricanes. But El Niño has the opposite effect in the eastern Pacific, where it can mean more storms. The ocean heat can also raise the <a href="https://theconversation.com/el-nino-is-coming-and-ocean-temps-are-already-at-record-highs-that-can-spell-disaster-for-fish-and-corals-202424">risk of marine heat waves</a> that can devastate corals and ecosystems fish rely on.</p>
<p>In the middle of the U.S., El Niño is generally associated with warmer and drier conditions that can mildly increase the <a href="https://www.agweb.com/news/crops/crop-production/el-nino-makes-its-grand-return-heres-what-it-tells-us-about-summer">chances of a bountiful corn crop</a>. </p>
<p>In contrast, El Niño can wreak havoc <a href="https://doi.org/10.3389/fsufs.2020.509914">on crops in Southern Africa</a> and <a href="https://theconversation.com/four-possible-consequences-of-el-nino-returning-in-2023-198105">Australia</a> and <a href="http://www.bom.gov.au/climate/updates/articles/a008-el-nino-and-australia.shtml">increase Australia’s fire risk</a> with dangerously dry conditions. Brazil and northern South America also tend to be drier, while parts of <a href="https://earthobservatory.nasa.gov/features/ElNino">Argentina and Chile tend to be wetter</a>.</p>
<figure class="align-center ">
<img alt="A stockman stands in the dry bed of a creek on his property in Australia in 2005 during a severe drought that coincided with El Nino." src="https://images.theconversation.com/files/531030/original/file-20230608-19-ey0ms3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/531030/original/file-20230608-19-ey0ms3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/531030/original/file-20230608-19-ey0ms3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/531030/original/file-20230608-19-ey0ms3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/531030/original/file-20230608-19-ey0ms3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/531030/original/file-20230608-19-ey0ms3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/531030/original/file-20230608-19-ey0ms3.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">Australia endured its worst drought in decades in 2005 with the combined effect of increasing temperatures and an El Niño.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/stockman-gordon-litchfield-from-wilpoorinna-sheep-and-news-photo/53030639">Ian Waldie/Getty Images</a></span>
</figcaption>
</figure>
<p>Of course, just because this is normally what happens doesn’t mean it happens every time. Witness California’s record rainfalls from <a href="https://www.nesdis.noaa.gov/news/more-heavy-rain-snow-and-wind-hitting-western-us">multiple atmospheric rivers</a> at the end of the last La Niña, which normally would mean dry conditions. </p>
<p>Every weather event is somewhat different, so the influence of El Niño is a matter of probability, not certainty. How El Niño and La Niña will be <a href="https://doi.org/10.3389/fclim.2022.941055">influenced over time by climate change</a> isn’t yet clear.</p>
<h2>The forecasts don’t all agree</h2>
<p>Is 2023 going to be a record-breaking year? That’s the <a href="https://www.ncei.noaa.gov/access/billions/">multibillion-dollar</a> question. </p>
<p>The National Weather Service declares the onset of El Niño when water temperatures are at least 0.9 F (0.5 C) above normal for a three-month period in what’s known as the <a href="https://svs.gsfc.nasa.gov/4695">Niño3.4 region</a>. That’s a large imaginary rectangle south of Hawaii along the equator.</p>
<figure class="align-center ">
<img alt="An animation shows satellite images of how temperatures headed up in the equatorial pacific, with a warm streak developing and intensifying west of South America." src="https://images.theconversation.com/files/530987/original/file-20230608-26-8kc8u1.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/530987/original/file-20230608-26-8kc8u1.gif?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=272&fit=crop&dpr=1 600w, https://images.theconversation.com/files/530987/original/file-20230608-26-8kc8u1.gif?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=272&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/530987/original/file-20230608-26-8kc8u1.gif?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=272&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/530987/original/file-20230608-26-8kc8u1.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=342&fit=crop&dpr=1 754w, https://images.theconversation.com/files/530987/original/file-20230608-26-8kc8u1.gif?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=342&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/530987/original/file-20230608-26-8kc8u1.gif?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=342&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Watching El Niño develop in the tropical Pacific, January to June 2023. The box shows the Niño3.4 region.</span>
<span class="attribution"><a class="source" href="https://www.climate.gov/">NOAA Climate.gov</a></span>
</figcaption>
</figure>
<p>For a strong El Niño, the Niño3.4 region needs to warm by 2.7 F (1.5 C) for three months. It’s not clear as of right now whether this El Niño will meet that threshold this year.</p>
<p>The National Oceanic and Atmospheric Administration’s first El Niño advisory of the year, released on June 8, sees an 84% chance of El Niño being greater than moderate by winter and a 56% chance that it will be strong.</p>
<p>Those forecasts can change, though, and <a href="https://www.washingtonpost.com/weather/2023/06/05/el-nio-forecast-climate-chaos/">different forecasting methods</a> offer <a href="https://twitter.com/ClimateOfGavin/status/1663949801015197697">different forecasts of the magnitude</a>.</p>
<p>“Dynamical” models, similar to the models used for typical weather forecasts, have projected a very strong El Niño, whereas “static” or statistical models are far less optimistic. Personally, <a href="https://science.gsfc.nasa.gov/sed/bio/robert.j.leamon">I’m a statistical modeler</a>, and my own model doesn’t suggest a strong El Niño in 2023. Rather, my model – like other static models – predicts that 2023 will fizzle out, and after a couple of quiet, or neutral, years, we will see a strong El Niño in 2026. I did get the recent unusual <a href="https://earthobservatory.nasa.gov/images/150691/la-nina-times-three">“triple dip” La Niña</a> right, but I’m willing to be proved wrong by observations, as any good scientist should be.</p>
<figure class="align-center ">
<img alt="A man in a raincoat stands under a big umbrella watching his backyard fill with rainwater in California in 2023. California saw record rain from atmospheric rivers in early 2023." src="https://images.theconversation.com/files/531029/original/file-20230608-26-5nz4h3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/531029/original/file-20230608-26-5nz4h3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/531029/original/file-20230608-26-5nz4h3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/531029/original/file-20230608-26-5nz4h3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/531029/original/file-20230608-26-5nz4h3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=504&fit=crop&dpr=1 754w, https://images.theconversation.com/files/531029/original/file-20230608-26-5nz4h3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=504&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/531029/original/file-20230608-26-5nz4h3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=504&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">El Niño often means winter rain for California. While it’s needed, it’s sometimes too much.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/man-watches-over-his-backyard-where-mud-is-beginning-to-news-photo/1246694514">Watchara Phomicinda/MediaNews Group/The Press-Enterprise via Getty Images</a></span>
</figcaption>
</figure>
<p>But no computer model of any flavor has had experience with the globally super-high ocean temperatures that are occurring right now. The Atlantic <a href="https://theconversation.com/atlantic-hurricane-season-2023-el-nino-and-extreme-atlantic-ocean-heat-are-about-to-clash-204670">is unusually warm</a>, and that could offset some of the usual forces that come with El Niño.</p><img src="https://counter.theconversation.com/content/205974/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Bob Leamon receives funding from NASA.</span></em></p>The official forecast calls for a strong El Niño by winter, but other models suggest it might dip in and out. An atmospheric scientist explains.Bob Leamon, Associate Research Scientist, University of Maryland, Baltimore CountyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2046702023-05-30T13:32:14Z2023-05-30T13:32:14ZAtlantic hurricane season 2023: El Niño and extreme Atlantic Ocean heat are about to clash<figure><img src="https://images.theconversation.com/files/525823/original/file-20230512-27-skp3ru.jpeg?ixlib=rb-1.1.0&rect=500%2C808%2C4292%2C2892&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Hurricane Florence, seen from the International Space Station in 2018. Atlantic hurricane season runs from June 1 to Nov. 30.</span> <span class="attribution"><a class="source" href="https://www.nasa.gov/press-release/nasa-scientists-available-for-interviews-throughout-hurricane-season">NASA</a></span></figcaption></figure><p>The <a href="https://www.nhc.noaa.gov/">Atlantic hurricane season</a> starts on June 1, and forecasters are keeping a close eye on rising ocean temperatures, and not just in the Atlantic. </p>
<p>Globally, warm sea surface temperatures that can fuel hurricanes have been <a href="https://climatereanalyzer.org/clim/sst_daily/">off the charts</a> in the spring of 2023, but what really matters for Atlantic hurricanes are the ocean temperatures in two locations: the North Atlantic basin, where hurricanes are born and intensify, and the eastern-central tropical Pacific Ocean, where El Niño forms.</p>
<p>This year, the two are in conflict – and likely to exert <a href="https://doi.org/10.1175/JCLI-D-13-00687.1">counteracting influences</a> on the crucial conditions that can make or break an Atlantic hurricane season. The result could be good news for the Caribbean and Atlantic coasts: a near-average hurricane season. But forecasters are warning that that hurricane forecast hinges on El Niño panning out.</p>
<h2>Ingredients of a hurricane</h2>
<p>In general, hurricanes are more likely to form and intensify when a tropical low-pressure system <a href="https://www.weather.gov/jetstream/tc">encounters an environment</a> with warm upper-ocean temperatures, moisture in the atmosphere, instability and weak vertical wind shear.</p>
<p>Warm ocean temperatures provide energy for a hurricane to develop. Vertical wind shear, or the difference in the strength and direction of winds between the lower and upper regions of a tropical storm, disrupts the organization of convection – the thunderstorms – and brings dry air into the storm, inhibiting its growth.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/LlXVikDkyTg?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">How hurricanes form. National Geographic.</span></figcaption>
</figure>
<h2>The Atlantic Ocean’s role</h2>
<p>The Atlantic Ocean’s role is pretty straightforward. Hurricanes draw energy from warm ocean water beneath them. The warmer the ocean temperatures, the better for hurricanes, all else being equal.</p>
<p>Tropical Atlantic Ocean temperatures were unusually warm during the <a href="https://theconversation.com/the-2020-atlantic-hurricane-season-is-so-intense-it-just-ran-out-of-storm-names-146506">most active Atlantic hurricane seasons</a> on recent record. The <a href="https://www.nhc.noaa.gov/data/tcr/index.php?season=2020&basin=atl">2020 Atlantic hurricane season</a> produced a record 30 named tropical cyclones, while the <a href="https://www.nhc.noaa.gov/data/tcr/index.php?season=2005&basin=atl">2005 Atlantic hurricane season</a> produced 28 named storms, a record 15 of which became hurricanes, including Katrina.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/525807/original/file-20230512-19-vlw6cv.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two maps showing tropical cyclone tracks. The tracks correspond with warmer water temperatures in the sea surface temperature maps below." src="https://images.theconversation.com/files/525807/original/file-20230512-19-vlw6cv.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/525807/original/file-20230512-19-vlw6cv.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=405&fit=crop&dpr=1 600w, https://images.theconversation.com/files/525807/original/file-20230512-19-vlw6cv.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=405&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/525807/original/file-20230512-19-vlw6cv.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=405&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/525807/original/file-20230512-19-vlw6cv.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=509&fit=crop&dpr=1 754w, https://images.theconversation.com/files/525807/original/file-20230512-19-vlw6cv.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=509&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/525807/original/file-20230512-19-vlw6cv.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=509&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 top images show where Atlantic tropical storms traveled in 2005, on the left, and in 2020, on the right. The lower images show the corresponding sea surface temperature anomalies for the August-October peak of the hurricane season compared with the August-October 1991-2020 average in degrees Celsius.</span>
<span class="attribution"><a class="source" href="https://psl.noaa.gov/data/gridded/data.noaa.ersst.v5.html">NOAA</a></span>
</figcaption>
</figure>
<h2>How the Pacific Ocean gets involved</h2>
<p>The tropical Pacific Ocean’s role in Atlantic hurricane formation is more complicated.</p>
<p>You may be wondering, how can ocean temperatures on the other side of the Americas influence Atlantic hurricanes? The answer lies in teleconnections. A teleconnection is a chain of processes in which a change in the ocean or atmosphere in one region leads to large-scale changes in atmospheric circulation and temperature that can influence the weather elsewhere.</p>
<figure class="align-center ">
<img alt="Sea surface temperature anomalies in degrees Celsius observed during three El Niño events show differences in location and strength of ocean warming." src="https://images.theconversation.com/files/525798/original/file-20230512-19-ts6p2q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/525798/original/file-20230512-19-ts6p2q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=189&fit=crop&dpr=1 600w, https://images.theconversation.com/files/525798/original/file-20230512-19-ts6p2q.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=189&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/525798/original/file-20230512-19-ts6p2q.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=189&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/525798/original/file-20230512-19-ts6p2q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=238&fit=crop&dpr=1 754w, https://images.theconversation.com/files/525798/original/file-20230512-19-ts6p2q.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=238&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/525798/original/file-20230512-19-ts6p2q.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=238&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Three examples of of how sea surface temperatures in the tropical Pacific change during El Niño events.</span>
<span class="attribution"><span class="source">Christina Patricola</span></span>
</figcaption>
</figure>
<p>One recurring pattern of tropical Pacific climate variability that initiates teleconnections is the <a href="https://theconversation.com/explainer-el-nino-and-la-nina-27719">El Niño-Southern Oscillation</a>.</p>
<p>When the tropical eastern-central Pacific Ocean is unusually warm, El Niño can form. During El Niño events, the warm upper-ocean temperatures change the <a href="https://www.climate.gov/news-features/blogs/enso/walker-circulation-ensos-atmospheric-buddy">vertical and east-west atmospheric circulation</a> in the tropics. That initiates a teleconnection by <a href="https://images.theconversation.com/files/525801/original/file-20230512-11356-c42xch.jpg">affecting the east-west winds</a> in the upper atmosphere throughout the tropics, ultimately resulting in stronger vertical wind shear in the Atlantic basin. That wind shear can tamp down hurricanes.</p>
<figure class="align-center ">
<img alt="Two illustrations of Walker Circulation patterns. El Niño reverses direction and strength compared with a neutral ENSO, or El Niño-Southern Oscillation." src="https://images.theconversation.com/files/525801/original/file-20230512-11356-c42xch.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/525801/original/file-20230512-11356-c42xch.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=578&fit=crop&dpr=1 600w, https://images.theconversation.com/files/525801/original/file-20230512-11356-c42xch.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=578&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/525801/original/file-20230512-11356-c42xch.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=578&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/525801/original/file-20230512-11356-c42xch.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=726&fit=crop&dpr=1 754w, https://images.theconversation.com/files/525801/original/file-20230512-11356-c42xch.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=726&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/525801/original/file-20230512-11356-c42xch.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=726&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">How El Niño conditions affect the Walker Circulation’s air flow, which can affect weather around the world.</span>
<span class="attribution"><a class="source" href="https://www.climate.gov/news-features/blogs/enso/walker-circulation-ensos-atmospheric-buddy">Fiona Martin/NOAA Climate.gov</a></span>
</figcaption>
</figure>
<p>That’s what forecasters are expecting to happen this summer. The latest forecasts show <a href="https://www.climate.gov/news-features/blogs/may-2023-enso-update-el-ni%C3%B1o-knocking-door">a 90% likelihood</a> that El Niño will develop by August and stay strong through the fall peak of the hurricane season.</p>
<h2>A tug of war between Atlantic and Pacific influences</h2>
<p><a href="https://scholar.google.com/citations?user=GZwohvoAAAAJ&hl=en">My research</a> and work by other atmospheric scientists has shown that a warm Atlantic and a warm tropical Pacific tend to counteract each other, leading to near-average Atlantic hurricane seasons. </p>
<p>Both <a href="https://doi.org/10.1175/JCLI-D-13-00687.1">observations and climate model simulations</a> have shown that outcome. The National Oceanic and Atmospheric Administration’s <a href="https://www.noaa.gov/news-release/2023-atlantic-hurricane-season-outlook">2023 forecast</a> calls for a near-average 12 to 17 named storms, five to nine hurricanes and one to four major hurricanes. An earlier outlook from <a href="https://tropical.colostate.edu/forecasting.html">Colorado State University</a> forecasters anticipates a slightly below-average season, with 13 named storms, compared with a climatological average of 14.4. </p>
<figure class="align-center ">
<img alt="Map showing warmer than normal temperatures across the Gulf of Mexico and Atlantic Ocean south of the Virginia." src="https://images.theconversation.com/files/525796/original/file-20230512-12302-prwz4c.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/525796/original/file-20230512-12302-prwz4c.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=464&fit=crop&dpr=1 600w, https://images.theconversation.com/files/525796/original/file-20230512-12302-prwz4c.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=464&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/525796/original/file-20230512-12302-prwz4c.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=464&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/525796/original/file-20230512-12302-prwz4c.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=583&fit=crop&dpr=1 754w, https://images.theconversation.com/files/525796/original/file-20230512-12302-prwz4c.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=583&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/525796/original/file-20230512-12302-prwz4c.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=583&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Sea surface temperature anomaly in degrees Celsius forecast for August to October 2023 shows a warm season relative to the 1991-2020 average for the same months.</span>
<span class="attribution"><a class="source" href="https://www.cpc.ncep.noaa.gov/products/CFSv2/CFSv2_body.html">Based on NCEP Climate Forecast System version 2 (CFSv2)</a></span>
</figcaption>
</figure>
<h2>The wild cards to watch</h2>
<p>Although tropical Atlantic and Pacific Ocean temperatures often inform skillful seasonal hurricane forecasts, there are other factors to consider and monitor.</p>
<p>First, will the forecast El Niño and Atlantic warming pan out? If one or the other does not, that could tip the balance in the tug of war between the influences.</p>
<p>The Atlantic Coast should be rooting for El Niño to develop as forecast, since such events often reduce hurricane impacts there. If this year’s expected Atlantic Ocean warming were instead <a href="https://www.climate.gov/news-features/blogs/enso/impacts-el-ni%C3%B1o-and-la-ni%C3%B1a-hurricane-season">paired with La Niña</a> – El Nino’s opposite, characterized by cool tropical Pacific waters – that could have led to a record-breaking active season instead.</p>
<p>Two other factors are also important. The <a href="https://doi.org/10.1175/JCLI-D-13-00483.1">Madden-Julian Oscillation</a>, a pattern of clouds and rainfall that travels eastward through the tropics on a time scale of 30 to 90 days, can either encourage or suppress tropical storm formation. And dust storms from the <a href="https://www.aoml.noaa.gov/saharan-air-layer/">Saharan air layer</a>, which contains warm, dry and dusty air from Africa, can suppress tropical cyclones.</p><img src="https://counter.theconversation.com/content/204670/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Christina Patricola receives funding from the U.S. Department of Energy and the National Science Foundation.</span></em></p>Current forecasts suggest a warm tropical Pacific will be interfering with what could otherwise be a ferocious Atlantic hurricane season.Christina Patricola, Assistant Professor of Atmospheric Sciences, Iowa State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2045262023-05-25T19:14:42Z2023-05-25T19:14:42Z2023 hurricane forecast: Get ready for a busy Pacific storm season, quieter Atlantic than recent years thanks to El Niño<figure><img src="https://images.theconversation.com/files/526058/original/file-20230514-129248-2f6227.jpg?ixlib=rb-1.1.0&rect=1615%2C5%2C1960%2C1281&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Twenty years of storm tracks in the Atlantic and eastern Pacific basins.</span> <span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Storm_track#/media/File:Global_tropical_cyclone_tracks-edit2.jpg">NASA</a></span></figcaption></figure><p>The official <a href="https://images.theconversation.com/files/528409/original/file-20230525-15023-h40sij.png">2023 hurricane season forecasts</a> were just released, and while the Atlantic may see <a href="https://www.noaa.gov/news-release/2023-atlantic-hurricane-season-outlook">an average storm season</a> this year, a busier-than-normal season is <a href="https://www.cpc.ncep.noaa.gov/products/Epac_hurr/Epac_hurricane.html">forecast in the eastern Pacific</a>, meaning heightened risks for Mexico and Hawaii.</p>
<p>A big reason is El Niño. </p>
<p>El Niño typically means trouble for the Pacific and a break for the Atlantic coast and Caribbean. But while this climate phenomenon is <a href="https://www.climate.gov/news-features/blogs/may-2023-enso-update-el-ni%C3%B1o-knocking-door">highly likely to form</a> this year, it isn’t a certainty before hurricane season ramps up this summer, and that makes it harder to know what might happen.</p>
<p>It’s also important to remember that even in quiet years, a single storm can cause enormous destruction.</p>
<p><iframe id="WRlId" class="tc-infographic-datawrapper" src="https://datawrapper.dwcdn.net/WRlId/3/" height="400px" width="100%" style="border: none" frameborder="0"></iframe></p>
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<p>As climate scientists, we study how climate patterns related to the frequency and intensity of hurricanes – information that is used to develop seasonal forecasts. Here is a quick look at how El Niño affects storms and why it tends to <a href="https://www.climate.gov/news-features/blogs/enso/impacts-el-ni%C3%B1o-and-la-ni%C3%B1a-hurricane-season">cause opposite effects</a> in two basins separated only by a narrow stretch of land. </p>
<h2>A tale of two basins</h2>
<p>It’s helpful to start by visualizing where tropical storms develop in each ocean.</p>
<p>In the North Atlantic, tropical storms typically form over the warm waters west of Africa. As they move westward, they often hit Caribbean islands before making landfall on the U.S. Gulf Coast and Eastern Seaboard, or they curve off into the Atlantic. </p>
<p>Those tropical storms and hurricanes have caused over <a href="https://coast.noaa.gov/states/fast-facts/hurricane-costs.html">a trillion dollars in damage</a> in the U.S. since 1981. <a href="https://www.climate.gov/news-features/blogs/2022-us-billion-dollar-weather-and-climate-disasters-historical-context">That damage</a> is expected to <a href="https://doi.org/10.1038/nclimate1357">continue to increase</a>, both because warming global temperatures fuel <a href="https://doi.org/10.1175/BAMS-D-19-0338.1">stronger storms</a> and because more people are building homes and businesses in harm’s way.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/524702/original/file-20230505-21-zw0ali.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Map showings location of storm formation and direction of movement." src="https://images.theconversation.com/files/524702/original/file-20230505-21-zw0ali.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/524702/original/file-20230505-21-zw0ali.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=181&fit=crop&dpr=1 600w, https://images.theconversation.com/files/524702/original/file-20230505-21-zw0ali.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=181&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/524702/original/file-20230505-21-zw0ali.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=181&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/524702/original/file-20230505-21-zw0ali.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=227&fit=crop&dpr=1 754w, https://images.theconversation.com/files/524702/original/file-20230505-21-zw0ali.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=227&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/524702/original/file-20230505-21-zw0ali.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=227&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Where tropical storms form in each basin.</span>
<span class="attribution"><a class="source" href="https://www.weather.gov/jetstream/tc">National Weather Service</a></span>
</figcaption>
</figure>
<p>In the eastern North Pacific, tropical storms tend to form closer to land, <a href="https://doi.org/10.1029/1999GL900533">between Mexico and Clipperton Island</a> off Central America. They typically move to the northwest before turning westward out to sea, sometimes inundating the Mexican coast known as the Mexican Riviera. Longer-tracked Pacific storms that move into the central Pacific can affect shipping and hit Hawaii, as <a href="https://www.cnn.com/2018/08/28/us/hawaii-tropical-storm-lane-flooding-wxc/index.html">Hurricane Lane did in 2018</a>.</p>
<p>While the Atlantic gets the most attention, largely because it gets more damage with more people and property in the way, the Pacific tends to get more storms, especially during El Niño years. It’s often a <a href="https://images.theconversation.com/files/528413/original/file-20230525-25-4e6pk1.png">seesaw pattern</a>, with a busy year in one basin and a quieter season in the other.</p>
<p><iframe id="p0KsO" class="tc-infographic-datawrapper" src="https://datawrapper.dwcdn.net/p0KsO/7/" height="400px" width="100%" style="border: none" frameborder="0"></iframe></p>
<h2>El Niño creates a seesaw pattern</h2>
<p>That <a href="https://www.climate.gov/news-features/blogs/enso/impacts-el-ni%C3%B1o-and-la-ni%C3%B1a-hurricane-season">seesaw pattern</a> is largely driven by the <a href="https://www.climate.gov/enso">El Niño-Southern Oscillation, or ENSO</a>, which includes varying strengths of El Niño and its opposite, La Niña.</p>
<p><a href="https://oceanservice.noaa.gov/facts/ninonina.html">During El Niño</a>, the trade winds that blow from east to west weaken, allowing warm ocean water to build up at the equator, west of South America. This causes a shift in the jet streams – strong upper-level winds – which affects rainfall and temperature patterns.</p>
<p>In the Atlantic Ocean, El Niño causes an area of low pressure in the upper atmosphere known as a trough and stronger upper-level winds, resulting in increased vertical wind shear – a change in wind speed or direction with height in the atmosphere. Wind shear can <a href="https://doi.org/10.1175/1520-0469(1996)053%3C2076:TEOVSO%3E2.0.CO;2">tilt and stabilize</a> storms, allowing <a href="https://doi.org/10.1175/1520-0493(1984)112%3C1649:ASHFPI%3E2.0.CO;2">fewer hurricanes</a> to form.</p>
<p>Conversely, El Niño typically causes an upper-level ridge, or area of high pressure, and decreased vertical wind shear in the eastern North Pacific basin, and often results in an active hurricane season.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/524703/original/file-20230505-27-wjdirr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Map showing where El Niño heat forms and impact on Atlantic and Pacific" src="https://images.theconversation.com/files/524703/original/file-20230505-27-wjdirr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/524703/original/file-20230505-27-wjdirr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=315&fit=crop&dpr=1 600w, https://images.theconversation.com/files/524703/original/file-20230505-27-wjdirr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=315&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/524703/original/file-20230505-27-wjdirr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=315&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/524703/original/file-20230505-27-wjdirr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=396&fit=crop&dpr=1 754w, https://images.theconversation.com/files/524703/original/file-20230505-27-wjdirr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=396&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/524703/original/file-20230505-27-wjdirr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=396&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Impacts of El Niño.</span>
<span class="attribution"><a class="source" href="https://www.climate.gov/news-features/blogs/enso/impacts-el-ni%C3%B1o-and-la-ni%C3%B1a-hurricane-season">NOAA Climate.gov</a></span>
</figcaption>
</figure>
<p>La Niña – El Niño’s opposite, with cooler water in the tropical Pacific – reverses this pattern. The <a href="https://www.noaa.gov/news/2020-atlantic-hurricane-season-takes-infamous-top-spot-for-busiest-on-record">record 2020</a> and <a href="https://www.washingtonpost.com/weather/2021/11/30/atlantic-hurricane-season-2021-recap/">destructive 2021</a> Atlantic hurricane seasons were both during strong La Niña years.</p>
<p>On longer time scales, the Atlantic Multidecadal Oscillation, a fluctuation of North Atlantic sea surface temperatures, affects hurricane activity in <a href="https://www.noaa.gov/stories/atlantic-high-activity-eras-what-does-it-mean-for-hurricane-season">cycles that span several decades</a>. The AMO’s current warm phase, which began in 1995, has hosted seven of the 10 busiest Atlantic hurricane seasons. Hurricane activity often lessens in a cool phase of the AMO, during which the Atlantic is on average about <a href="https://www.aoml.noaa.gov/phod/amo_faq.php">1 degree Fahrenheit (0.6 Celsius) cooler</a>. </p>
<h2>Who faces the greatest risk in the Pacific?</h2>
<p>El Niño also changes who is at risk in the Pacific.</p>
<p>During El Niño events, storms in the eastern North Pacific <a href="https://doi.org/10.1029/1999GL900533">tend to form farther to the west</a>. With these events, the <a href="https://doi.org/10.1175/2010MWR3538.1">environmental conditions in the western portion</a> of the basin tend to become more conducive than normal to tropical cyclones, such as having reduced environmental vertical wind shear and warmer ocean temperatures. That <a href="https://doi.org/10.1175/1520-0442(1997)010%3C2683:TCOITV%3E2.0.CO;2">places Hawaii and the central Pacific at greater risk</a> from damaging storms than normal.</p>
<figure class="align-center ">
<img alt="Three people stand under umbrellas on a bridge watching a rushing river below. It's clearly well beyond its banks, with a tree in the middle of the water, and moving so fast spray is coming up." src="https://images.theconversation.com/files/528405/original/file-20230525-19-834g4a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/528405/original/file-20230525-19-834g4a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=391&fit=crop&dpr=1 600w, https://images.theconversation.com/files/528405/original/file-20230525-19-834g4a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=391&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/528405/original/file-20230525-19-834g4a.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=391&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/528405/original/file-20230525-19-834g4a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=491&fit=crop&dpr=1 754w, https://images.theconversation.com/files/528405/original/file-20230525-19-834g4a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=491&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/528405/original/file-20230525-19-834g4a.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=491&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Hurricane Lane brought more than a foot of rain and flash flooding to Hawaii in 2018.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/people-watch-the-wailuku-river-flood-waters-on-the-big-news-photo/1022108102">Mario Tama/Getty Images</a></span>
</figcaption>
</figure>
<p>The highly destructive Hurricanes <a href="https://www.nhc.noaa.gov/data/tcr/EP132013_Manuel.pdf">Manuel in 2013</a> and <a href="https://www.nhc.noaa.gov/data/tcr/EP242018_Willa.pdf">Willa in 2018</a> show the immense impact Pacific storms can have in the region. Both triggered widespread flooding and mudslides in Mexico, and together led to over 125 deaths. In Hawaii, <a href="https://www.weather.gov/media/publications/assessments/iniki1.pdf">Hurricane Iniki</a>’s storm surge and winds in 1992 destroyed over 1,400 homes on Kauai and damaged thousands more.</p>
<p>El Niño years also increase the viability of storms affecting the southwestern U.S. In 1997, <a href="https://doi.org/10.1175/1520-0493(1999)127%3C2440:ENPHSO%3E2.0.CO;2">multiple storms affected California and Arizona</a>, including some that moved into the region after landfall in Mexico. Famously, in 2014, rough surf and swells associated with Hurricane Marie caused <a href="https://www.nhc.noaa.gov/data/tcr/EP132014_Marie.pdf">over US$16 million in damage</a> at the Port of Long Beach. </p>
<h2>Why 2023 hurricane forecasts are so uncertain</h2>
<p>Forecasting the 2023 hurricane seasons is proving to be challenging for another reason: The Atlantic has abnormally warm sea surface temperatures this year, and that can power hurricanes – if storms are able to form. </p>
<p>Will the warm waters of the Atlantic overcome the unfavorable conditions brought by the El Niño? We’ll soon know. </p>
<p>The eastern Pacific hurricane season started May 15, and the Atlantic season starts June 1, with both running through Nov. 30. </p>
<p>In its <a href="https://www.noaa.gov/news-release/2023-atlantic-hurricane-season-outlook">2023 Atlantic hurricane outlook</a> released in late May, the National Oceanic and Atmospheric Administration forecast 12 to 17 named storms, five to nine hurricanes and one to four major hurricanes. In the <a href="https://www.cpc.ncep.noaa.gov/products/Epac_hurr/Epac_hurricane.html">eastern Pacific, NOAA forecasts</a> 14 to 20 named storms, seven to 11 hurricanes and four to eight major hurricanes. For the <a href="https://www.noaa.gov/news-release/noaa-predicts-near-or-above-normal-2023-central-pacific-hurricane-season">central Pacific</a>, including Hawaii, NOAA’s forecast includes four to seven cyclones, also above or close to average.</p>
<p>Surprisingly, the Atlantic has already seen its first storm of the year – a storm in January was recently <a href="https://www.nhc.noaa.gov/archive/text/PNSNHC/2023/PNSNHC.202305111500.txt">classified as a subtropical cyclone</a>. This is rare. <a href="https://doi.org/10.1007/s00704-021-03734-6">Our research</a> shows the median date of the first named tropical cyclone is May 30 in the Pacific and June 20 in the Atlantic, though Atlantic storms have been occurring, on average, earlier each year. We should expect the next named Atlantic and Pacific storms – <a href="https://www.nhc.noaa.gov/aboutnames.shtml">Arlene and Adrian</a>, respectively – in the coming weeks.</p>
<p><em>This article was updated May 30, 2023, to corrects reference to storms forming off Africa.</em></p><img src="https://counter.theconversation.com/content/204526/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kelsey Ellis receives funding from the National Oceanic and Atmospheric Administration and the National Science Foundation. </span></em></p><p class="fine-print"><em><span>Nicholas Grondin 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>El Niño years put Hawaii and the Mexican Riviera on alert for destructive tropical storms and hurricanes.Kelsey Ellis, Associate Professor of Geography, University of TennesseeNicholas Grondin, Recent PhD Graduate in Geography, University of TennesseeLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2028642023-04-29T18:47:55Z2023-04-29T18:47:55ZFur seals on a remote island chain are exposed to huge amounts of toxic heavy metals – yet somehow, they’re healthy<figure><img src="https://images.theconversation.com/files/522568/original/file-20230424-26-b71nkr.JPG?ixlib=rb-1.1.0&rect=0%2C0%2C4608%2C3456&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Juan Fernández fur seals were once hunted for their semi-waterproof fur.</span> <span class="attribution"><span class="source">Constanza Toro Valdivieso</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Juan Fernández fur seals are so poorly understood that they were considered extinct for nearly a century before a remnant population which had managed to evade generations of hunters was rediscovered in the 1960s. </p>
<p>Their mysterious nature owes a lot to their seclusion on an archipelago of the same name 600km off the Chilean coast. These remote islands are situated in a protected national park – the last place you might expect to find animals exposed to high levels of pollution. But samples I collected and analysed with colleagues tell us something different.</p>
<p>Our <a href="https://doi.org/10.1098/rsos.221237">most recent study</a> analysed fur seal poo and found concentrations of cadmium and mercury that were among the highest reported for any mammal worldwide. This species is ingesting exceptionally high concentrations of these toxic heavy metals through its diet, but how they enter the food chain proved to be more complicated than we anticipated.</p>
<p>By studying these marine mammals, scientists can discover how polluted the wider environment is. Better yet, we may learn a trick or two from them on surviving amid pollution.</p>
<h2>Where are the heavy metals coming from?</h2>
<p>Some metals, such as zinc and iron, are essential micronutrients which we’re encouraged to include in our diet. This is not the case with mercury and cadmium. <a href="https://dictionary.apa.org/mad-hatters-disease">Mad Hatter’s disease</a> is a neurological disorder associated with mercury intoxication, while <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5734474/#:%7E:text=Itai%2Ditai%20disease%20is%20caused,associated%20with%20renal%20tubular%20dysfunction.">Itai-itai disease</a>, which translates from the Japanese as “it hurts it hurts”, is a condition causing severe bone pain and weakening resulting from chronic cadmium poisoning that affected people working in contaminated rice fields in Toyama prefecture, Japan. These heavy metals are highly toxic even in small amounts, and they have few known biological uses.</p>
<p>Heavy metals occur naturally in the Earth’s crust and are emitted by volcanic eruptions or as a result of rocks being worn down by the weather. They’re also produced during mining, waste incineration and steelmaking. With the Juan Fernández Islands being so far from any major industries, we were initially perplexed by the seemingly toxic diet of these fur seals.</p>
<figure class="align-center ">
<img alt="A person wearing a head scarf and holding a shovel operates a machine crushing ore." src="https://images.theconversation.com/files/522612/original/file-20230424-26-dnh5mj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/522612/original/file-20230424-26-dnh5mj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/522612/original/file-20230424-26-dnh5mj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/522612/original/file-20230424-26-dnh5mj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/522612/original/file-20230424-26-dnh5mj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/522612/original/file-20230424-26-dnh5mj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/522612/original/file-20230424-26-dnh5mj.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">Miners use mercury to extract gold from its ore.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/chami-mauritania-january-20-2019-artisanal-2091743224">Senderistas/Shutterstock</a></span>
</figcaption>
</figure>
<p>But the archipelago is located on the edge of a rotating current known as the South Pacific subtropical gyre which has gathered a <a href="https://doi.org/10.1016/j.marpolbul.2018.09.031">colossal</a> amount of ocean plastic. It is estimated that the plastic patch is <a href="https://www.snexplores.org/article/expedition-finds-south-pacific-plastic-patch-bigger-india">bigger than India</a>.</p>
<p>Unfortunately, Juan Fernández fur seal mothers must travel huge distances through this plastic cloud to hunt the nutrient-rich prey they need to carry on their pregnancies and make enough fatty milk for their pups. <a href="https://doi.org/10.1016/j.envint.2019.104937">Evidence shows</a> plastic debris can absorb toxins, including cadmium. So were the fur seals accidentally ingesting plastic or eating animals that had? The answer was more complicated.</p>
<p>Phytoplankton, or algae, are microscopic organisms similar to plants on land in that they contain chlorophyll and synthesise food from sunlight. Algae use micronutrients such as zinc to carry out their metabolism, but some parts of the ocean, including gyres, tend to have low concentrations. <a href="https://doi.org/10.1016/j.epsl.2019.02.031">Studies</a> have shown that phytoplankton in these regions have evolved to use cadmium instead: the only known biological process in which cadmium is useful.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/522614/original/file-20230424-24-k614lx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Four world maps showing where different sizes of plastic are accumulating in the ocean." src="https://images.theconversation.com/files/522614/original/file-20230424-24-k614lx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/522614/original/file-20230424-24-k614lx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=344&fit=crop&dpr=1 600w, https://images.theconversation.com/files/522614/original/file-20230424-24-k614lx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=344&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/522614/original/file-20230424-24-k614lx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=344&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/522614/original/file-20230424-24-k614lx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=432&fit=crop&dpr=1 754w, https://images.theconversation.com/files/522614/original/file-20230424-24-k614lx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=432&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/522614/original/file-20230424-24-k614lx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=432&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The South Pacific gyre is a global hotspot for tiny plastic fragments.</span>
<span class="attribution"><a class="source" href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0111913">Eriksen et al. (2014)/PLOS One</a></span>
</figcaption>
</figure>
<p>Tiny, microscopic animals called zooplankton eat the cadmium-contaminated algae which are then eaten by fish and larger animals, which eventually end up in the bellies of octopus and squid, which are among the fur seal’s favourite food. These molluscs can accumulate large quantities of heavy metals in their kidneys and, especially, in an organ known as the hepatopancreas. Unlike humans, who largely only eat the tentacles, fur seals consume the whole prey, including the heavy metal-rich organs. So it may be that an evolutionary adaptation by phytoplankton has increased the risk of cadmium exposure in animals higher up the food chain.</p>
<h2>A new mystery</h2>
<p>Since cadmium severely damages the skeletons of mammals including humans, we wanted to see, after finding such vast quantities of cadmium in fur seal poo, if this heavy metal was being absorbed into their bones. </p>
<p>As expected, Juan Fernández fur seal skeletons were loaded with cadmium. But, to our surprise, we could not find any other mineral changes which would be expected in an animal suffering from cadmium poisoning. This suggests this species has somehow adapted to withstand the toxic heavy metal.</p>
<p>If that is the case, it may indicate that Juan Fernández fur seals have been exposed to natural sources of cadmium for thousands of years. To understand how, we must find a way to differentiate natural from man-made sources.</p>
<p>The reward for doing so may be great. There is sure to be much to learn from the resilience of this enigmatic species, which overcame extinction and still manages to thrive in a world where pollution has flooded even the most remote corners.</p>
<hr>
<figure class="align-right ">
<img alt="Imagine weekly climate newsletter" src="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p class="fine-print"><em><span>Constanza Toro Valdivieso is affiliated with Fundación Endémica, Chile. </span></em></p>The mystery surrounding a forgotten marine mammal, a remote archipelago and man-made pollution.Constanza Toro Valdivieso, Postdoctoral Researcher in Molecular Biology, University of CambridgeLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2044472023-04-28T14:53:02Z2023-04-28T14:53:02ZWe found long-banned pollutants in the very deepest part of the ocean<figure><img src="https://images.theconversation.com/files/523295/original/file-20230427-16-67rhr1.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C3308%2C2194&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Scientists found PCBs 8 kilometres below the waves.</span> <span class="attribution"><span class="source">dimitris_k / shutterstock</span></span></figcaption></figure><p>I was part of a team that recently <a href="https://www.nature.com/articles/s41467-023-37718-z">discovered human-made pollutants</a> in one of the deepest and most remote places on Earth – the Atacama Trench, which goes down to a depth of 8,000 meters in the Pacific Ocean. The presence of polychlorinated biphenyls (PCBs) in such a remote location emphasises a crucial fact: no place on Earth is free from pollution.</p>
<p>PCBs were produced in large quantities from the 1930s to the 1970s, mostly in the northern hemisphere, and were used in electrical equipment, paints, coolants and lots of other products. In the 1960s, it became clear they were <a href="https://www.jstor.org/stable/4311963">harming marine life</a>, leading to an almost global ban on their use in the mid-1970s. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/523255/original/file-20230427-24-m0y3en.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Shaded map of western South America" src="https://images.theconversation.com/files/523255/original/file-20230427-24-m0y3en.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/523255/original/file-20230427-24-m0y3en.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=1571&fit=crop&dpr=1 600w, https://images.theconversation.com/files/523255/original/file-20230427-24-m0y3en.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=1571&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/523255/original/file-20230427-24-m0y3en.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=1571&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/523255/original/file-20230427-24-m0y3en.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1974&fit=crop&dpr=1 754w, https://images.theconversation.com/files/523255/original/file-20230427-24-m0y3en.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1974&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/523255/original/file-20230427-24-m0y3en.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1974&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Sometimes called the Peru-Chile Trench, the Atacama Trench is visible in dark blue on this relief map (sea level is green and mountains are red).</span>
<span class="attribution"><a class="source" href="https://upload.wikimedia.org/wikipedia/commons/c/c4/Peru-Chile_trench.jpg">NOAA</a></span>
</figcaption>
</figure>
<p>However, because they take decades to break down, PCBs can travel long distances and spread to places far from where they were first used, and they continue to circulate through ocean currents, winds and rivers.</p>
<p>Our <a href="https://www.nature.com/articles/s41467-023-37718-z">study</a> took place in the Atacama Trench, which tracks the coast of South America for almost 6,000km. Its deepest point is roughly as deep as the Himalayas are high. </p>
<p>We collected sediment from five sites in the trench at different depths ranging from 2,500m to 8,085m. We sliced each sample into five layers, from surface sediment to deeper mud layers, and found PCBs in all of them.</p>
<h2>Pollutants stick to dead plankton</h2>
<p>In that part of the world, ocean currents bring cold and nutrient-rich waters to the surface, which means lots of plankton – the tiny organisms at the bottom of the food web in the oceans. When plankton die, their cells sink to the bottom, carrying with them pollutants such as PCBs. But PCBs don’t dissolve well in water and instead prefer to bind to tissues rich in fat and other bits of living or dead organisms, such as plankton. </p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/523297/original/file-20230427-16-b29mjq.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Machine dangles off edge of boat" src="https://images.theconversation.com/files/523297/original/file-20230427-16-b29mjq.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/523297/original/file-20230427-16-b29mjq.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=900&fit=crop&dpr=1 600w, https://images.theconversation.com/files/523297/original/file-20230427-16-b29mjq.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=900&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/523297/original/file-20230427-16-b29mjq.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=900&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/523297/original/file-20230427-16-b29mjq.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1131&fit=crop&dpr=1 754w, https://images.theconversation.com/files/523297/original/file-20230427-16-b29mjq.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1131&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/523297/original/file-20230427-16-b29mjq.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">Scientists used this ‘core sampler’ to extract sediment from the bottom of the trench.</span>
<span class="attribution"><span class="source">Anni Glud/SDU</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Since seabed sediment contains a lot of remnants of dead plants and animals, it serves as an important sink for pollutants such as PCBs. About 60% of PCBs released during the 20th century are <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2018GB006018">stored in deep ocean sediment</a>.</p>
<p>A deep trench like the Atacama acts like a funnel that collects bits of dead plants and animals (what scientists refer to as “organic carbon”) that come falling down through the water. There is a lot of life in the trench, and microbes then degrade the organic carbon in the seafloor mud. </p>
<p>We found that the organic carbon at the deepest locations in the Atacama Trench was more degraded than at shallower places. At the greatest depths, there were also higher concentrations of PCB per gram of organic carbon in the sediment. The organic carbon in the mud is more easily degraded than the PCBs, which remain and can accumulate in the trench.</p>
<h2>A look into the past</h2>
<p>The storage of pollutants means ocean sediment can be used as a rear-view mirror on the past. It is possible to determine when a sediment layer accumulated on the seafloor, and by analysing pollutants in different layers we can gain information about their concentrations over time. </p>
<p>The sediment archive in the Atacama Trench surprised us. PCB concentrations were highest in the surface sediment, which contrasts to what we usually find in lakes and seas. Typically, the highest concentrations are found in lower layers of sediment that were deposited in the 1970s through to the 1990s, followed by a decrease in concentrations towards the surface, reflecting the ban and reduced emissions of PCBs. </p>
<p>For now, we still don’t understand why the Atacama would be different. It is possible that we didn’t look at the sediment closely enough to detect small variations in PCBs, or that concentrations have not yet peaked in this deep trench. </p>
<p>These concentrations are still quite low, hundreds of times lower than in areas close to human pollution sources such as the <a href="https://www.sciencedirect.com/science/article/pii/S0045653517316545">Baltic Sea</a>. But the fact we have found any pollution whatsoever shows the magnitude of humanity’s influence on the environment.</p>
<p>What we can say for sure is that the more than <a href="https://pubs.acs.org/doi/10.1021/acs.est.9b06379">350,000 chemicals</a> currently in use globally come at a cost of polluting the environment and ourselves. Pollutants have now been found buried below the bottom of one of the world’s deepest ocean trenches – and they’re not going anywhere. </p>
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<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">
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<p class="fine-print"><em><span>Anna Sobek receives funding from The Swedish Research Council (VR), Swedish Research Council for Sustainable Development (Formas), Swedish Environmental Protection Agency. </span></em></p>No place on Earth is free from pollution.Anna Sobek, Professor of Environmental Chemistry and Head of Department of Environmental Sciences, Stockholm UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2034972023-04-14T05:16:10Z2023-04-14T05:16:10ZAnalyzing the fat of killer whales reveals what they eat<figure><img src="https://images.theconversation.com/files/520684/original/file-20230413-28-mo8doc.jpg?ixlib=rb-1.1.0&rect=150%2C0%2C3197%2C1660&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Killer whales are the apex predator in the oceans.</span> <span class="attribution"><span class="source">(Shutterstock)</span></span></figcaption></figure><iframe style="width: 100%; height: 100px; border: none; position: relative; z-index: 1;" allowtransparency="" allow="clipboard-read; clipboard-write" src="https://narrations.ad-auris.com/widget/the-conversation-canada/analyzing-the-fat-of-killer-whales-reveals-what-they-eat" width="100%" height="400"></iframe>
<p>Scientists are studying the diets of the oceans’ top predators as they change in response to their environments. This is because how much and what they eat can affect <a href="https://doi.org/10.1073/pnas.1635156100">how ecosystems function</a>. </p>
<p>And while researchers know that killer whales, also known as orcas, are <a href="https://www.newscientist.com/definition/orcas-orcinus-orca/">the oceans’ apex predators</a>, our understanding of their diet — particularly the quantity of each species they consume — remains incomplete. </p>
<p>This is especially true for remote populations that cannot be observed year-round. </p>
<p>But there’s now a way to recreate killer whales’ precise diets by using only a sample of their skin and fat. My research team developed a promising technique that reveals <a href="https://doi.org/10.1111/1365-2656.13920">these wild predators’ diets across the North Atlantic Ocean</a>.</p>
<h2>Multiple feeding strategies</h2>
<p>Killer whales are intelligent predators that are known to adopt specific hunting techniques, ranging from <a href="https://doi.org/10.1016/j.mambio.2017.03.006">carousel feeding — co-operatively herding and then feeding on — herring</a>, to co-operatively creating <a href="https://doi.org/10.1111/j.1748-7692.2010.00453.x">waves that can dislodge seals from ice floes</a>. As a result, they can hunt nearly any species, from fish to fur seals to blue whales, throughout the world’s oceans. </p>
<p>Depending on their location and evolutionary history, different groups of killer whales have developed different <a href="https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/ecotype">ecotypes — unique diets and lifestyles</a>. The most notorious ecotypes are the <a href="https://publications.gc.ca/site/eng/452379/publication.html">transient</a> and <a href="https://www.fisheries.noaa.gov/west-coast/endangered-species-conservation/southern-resident-killer-whale-orcinus-orca">resident</a> killer whales in the Eastern North Pacific. </p>
<p>These ecotypes have been extensively studied for decades, as the killer whales inhabit densely populated areas, which allows scientists to observe these individuals year-round.</p>
<p>In these populations, scientists found evidence of “<a href="https://doi.org/10.1146/annurev-environ-110615-085622">trophic cascades</a>,” the effects of predator consumption on the rest of the food web. Killer whales had top-down effects on the density of kelp forests; the killer whales greatly reduced the sea otter population, which caused the sea urchins — the sea otters’ main food source — to proliferate and decimate the kelp forests.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/520089/original/file-20230410-7479-jlgmrx.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="four killer whales, only their fins are visible" src="https://images.theconversation.com/files/520089/original/file-20230410-7479-jlgmrx.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/520089/original/file-20230410-7479-jlgmrx.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/520089/original/file-20230410-7479-jlgmrx.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/520089/original/file-20230410-7479-jlgmrx.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/520089/original/file-20230410-7479-jlgmrx.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/520089/original/file-20230410-7479-jlgmrx.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/520089/original/file-20230410-7479-jlgmrx.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A group of killer whales in Vestmannaeyjar, Iceland, travelling slowly after feasting on herring.</span>
<span class="attribution"><span class="source">(A. Remili)</span>, <span class="license">Author provided</span></span>
</figcaption>
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<h2>North Atlantic mystery</h2>
<p>Comparing different groups of killer whales around the world reveals that there is still a lot we don’t know about them. Figuring out what killer whales living in remote parts of the Arctic eat, like in Baffin Bay, Greenland and Arctic Norway, is challenging. Observation of <a href="https://doi.org/10.1111/j.1748-7692.2012.00604.x">feeding events can be difficult</a> in the unstable waters of the Arctic Ocean. </p>
<p>Initial studies suggested there were <a href="https://doi.org/10.1111/j.1365-294X.2009.04407.x">two types of killer whales in the North Atlantic</a>: those that prey on marine mammals, and the other group that eats fish and occasionally seals. However, the lack of data, combined with emerging evidence has led to scientists proposing to <a href="https://doi.org/10.1111/mms.12964">retire this classification</a>. It appears that there is a more diverse range of diets in some North Atlantic populations.</p>
<p>Due to the challenge of collecting observation data, researchers have focused their efforts on the <a href="https://doi.org/10.1111/j.1748-7692.2009.00354.x">chemical signals</a> they can measure inside the killer whales’ skin and blubber. These chemical signals can consist of lipids or stable isotopes which tell us what the whales eat and how they impact the food chain. </p>
<p>Our technique measures the <a href="https://doi.org/10.1038/s41598-022-11660-4">lipid composition in the whale’s fat</a>, and uses a computer program to recreate the most probable proportion of each prey species to an individual’s diet. </p>
<p>All that is required are multiple lipid “signatures” — that represent the proportion of each fatty acid in the whale’s blubber — from the killer whales and from their potential prey.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/qJh-1XRxTq8?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Samples of killer whale blubber reveal detailed information about their preferred food sources.</span></figcaption>
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<h2>Fat studies</h2>
<p>Our open-access research, recently published in the <a href="https://doi.org/10.1111/1365-2656.13920"><em>Journal of Animal Ecology</em></a>, used a technique called <a href="https://doi.org/10.1111/2041-210X.12740">quantitative fatty acid signature analysis</a> to reveal the diets of nearly 200 North Atlantic killer whales.</p>
<p>We also measured lipid compositions in over 900 prey samples. The results showed a range of feeding strategies across the ocean. In the western part of the North Atlantic, killer whales ate mainly other whales (like large baleen whales, belugas and narwhals); killer whales in Greenland preferred seals and in Norway, they showed a preference for fish like herring.</p>
<p>Using this technique, scientists can now estimate the exact percentage of different species in each whale’s diets. But what surprised us the most was the level of variation between individual diets within each population. </p>
<p>In the western North Atlantic, individuals focus either on cetaceans — marine mammals like belugas and narwhals — or seals. In the mid-North Atlantic, killer whales would feed on all available prey. And for the most part, eastern North Atlantic killer whales seem to keep to a diet rich in fish. Several individual killer whales in Norway and Iceland supplement fish with marine mammals.</p>
<p>Our study is the first and largest of its kind on killer whales, and our findings encourage us to further investigate killer whale diets at the individual scale. We now know that individuals within the same populations can have different diets. </p>
<p>This not only translates to different contaminant exposures and health risks for these top predators, but also represents different feeding strategies throughout the Arctic Ocean.</p>
<p>This approach allows us to measure future shifts in these predators’ diets and understand how they may impact Arctic food webs. Because of climate change, killer whales are <a href="https://doi.org/10.1111/j.1748-7692.2011.00489.x">progressively moving further into the Arctic</a>.</p>
<p>Their presence and a potential increase in consumption of Arctic species could change the ecosystem dynamics in the North. Further research using this technique on samples collected over an extensive period could allow researchers to detect shifts in the whales’ diets and ecosystem.</p><img src="https://counter.theconversation.com/content/203497/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Anaïs Remili 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>By analyzing small samples of killer whale fat, scientists can learn about the diets of different killer whale populations. This has implications for our understanding of changing ecosystems.Anaïs Remili, PhD Candidate, Renewable Resources, McGill UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2019402023-03-16T19:12:05Z2023-03-16T19:12:05ZThe flap of a butterfly’s wings: why autumn is not a good time to predict if El Niño is coming<figure><img src="https://images.theconversation.com/files/515674/original/file-20230316-26-allg6u.jpg?ixlib=rb-1.1.0&rect=49%2C0%2C5472%2C3645&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>Remember the butterfly effect? It was a popular summary of chaos theory suggesting a butterfly flapping its wings in the Amazon could cause a tornado in Texas. </p>
<p>Right now, a version of this is making it hard for us to predict whether an <a href="https://oceanservice.noaa.gov/facts/ninonina.html">El Niño event</a> is coming. </p>
<p>After three consecutive La Niña years, that part of the cycle is <a href="http://www.bom.gov.au/climate/enso/#:%7E:text=Pacific%20Ocean,-Forecast&text=El%20Ni%C3%B1o%20typically%20produces%20drier,been%20declared%20in%20September%202022.">officially over</a>. But it’s not certain an El Niño will replace it. Australia’s Bureau of Meteorology this week announced an <a href="http://www.bom.gov.au/climate/enso/outlook/">El Niño watch</a> – a “wait and see” forecast giving us a 50% chance of an El Niño forming later this year. Other climate forecasting agencies around the world are sending a <a href="https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/ensodisc.shtml">similar message</a> to the Bureau of Meteorology’s, that we are on an El Niño watch. </p>
<p>While the conditions seem right for El Niño to form and likely bring hotter, drier weather to Australia, the world’s chaotic climate system is in a very unpredictable state. Fast forward three months, and our models will be much more certain about whether El Niño really is coming – or whether the system will remain in a neutral, or near-normal, state. </p>
<h2>Why can’t we predict what’s going to happen?</h2>
<p>At this time of year, the El Niño-Southern Oscillation (ENSO) cycle is at its most susceptible to change. Right now, the subsurface waters of the equatorial western Pacific are warmer than usual. If this water rises from deeper down to the surface of the ocean, it will interact with the atmosphere. This usually leads to more rain and floods for Chile, drier, hotter weather for Australia, and a variety of other effects worldwide. </p>
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<strong>
Read more:
<a href="https://theconversation.com/why-el-nino-doesnt-mean-certain-drought-197678">Why El Niño doesn't mean certain drought</a>
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<p>But this isn’t inevitable. Let’s say a sudden burst of wind strikes, forcing warmer water to stay down deeper. This can disturb the whole cycle. Unexpected windbursts at this time of year can even tip the system into a different mode, ending up neutral or as a La Niña event. </p>
<p>Among climate scientists, this is known as the <a href="https://www.climate.gov/news-features/blogs/enso/spring-predictability-barrier-we%E2%80%99d-rather-be-spring-break">predictability barrier</a> – and it’s why we can’t say for certain an El Niño is coming until later in the year. </p>
<h2>Have we seen unexpected swings in the cycle before?</h2>
<p>Yes, most recently in 2014. Early that year, climate models were predicting a truly enormous El Niño was set to begin. </p>
<p>But the monster El Niño <a href="https://www.nature.com/articles/nclimate2775">didn’t happen</a>. Cooler water flowed into the south-eastern Pacific at a critical time of year, while the unusual timing of westerly windbursts kept the warmer water down deeper. </p>
<p>The end result was that the whole system was nudged into a different configuration of a weak El Niño. It took another year for a full El Niño to develop. This time, it was <a href="https://www.nature.com/articles/s41598-018-29130-1">very strong</a>. </p>
<p>Could we really see a fourth La Niña? It could happen but it would be very unusual, given we’ve never seen four years of successive La Niña conditions. At present, the heat build-up under the surface of the equatorial Pacific suggests an El Niño is coming, but it’s not a given. </p>
<h2>Why do we get these cycles anyway?</h2>
<p>We believe the El Niño-La Niña cycle has a very long history, dating back to <a href="https://www.nature.com/articles/nature.2016.20334#:%7E:text=The%20Pacific%20Ocean%20was%20born,lava%20welled%20up%20from%20below.">the formation</a> of the Pacific Ocean about 190 million years ago. </p>
<p>That’s because this ocean basin is the largest on Earth – and has a lot of seawater sitting along the equator. In our models, we can see the El Niño cycle forming out of the fluid dynamics, as <a href="https://theconversation.com/explainer-el-nino-and-la-nina-27719">warmer or cooler water moves</a> across the ocean. </p>
<p>The Atlantic has a smaller version, named the Atlantic Niño. Why is it smaller? Because there’s much less water along the equator in the Atlantic. As a result, the Atlantic Niño has much less of an effect on weather globally. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/515673/original/file-20230316-14-sqwy47.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Pacific ocean atlantic ocean centred maps" src="https://images.theconversation.com/files/515673/original/file-20230316-14-sqwy47.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/515673/original/file-20230316-14-sqwy47.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=304&fit=crop&dpr=1 600w, https://images.theconversation.com/files/515673/original/file-20230316-14-sqwy47.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=304&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/515673/original/file-20230316-14-sqwy47.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=304&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/515673/original/file-20230316-14-sqwy47.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=382&fit=crop&dpr=1 754w, https://images.theconversation.com/files/515673/original/file-20230316-14-sqwy47.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=382&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/515673/original/file-20230316-14-sqwy47.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=382&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The El Nino cycle’s significance is due to the sheer size of the Pacific – and the amount of water along the equator. By contrast, the Atlantic’s equatorial waters are more limited.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>So when will we know for sure?</h2>
<p>El Niño and La Niña are at their strongest over December and January, though the effects and their timing can differ in Australia depending on where in the country you are. These cycles usually end some time between February and May. </p>
<p>The popular understanding of the butterfly effect and chaos science often gets one thing wrong. Chaotic systems like the world’s weather are not always unpredictable, but can be more or less sensitive to small changes at different times. Between March and May, it can take just a small nudge to flip the system. Later in the year, as either an El Niño, neutral phase or La Niña gathers pace, it is much harder to change course. </p>
<p>It’s like a ball poised on top of a high hill. A very tiny push is enough to send the ball rolling down either one side of the hill or another. The push might even be so tiny you can’t measure it accurately. </p>
<p>That’s why it’s so difficult to predict what’s going to happen, even though we understand the physics behind these events fairly well. The Pacific Ocean and the air overhead are extremely sensitive to “pushes” in any direction from March to May. </p>
<p>But once the ball rolls down one side rather than another, it’s much easier to predict which way it will keep rolling. By June or July, the ball is already rolling down the hill on whichever side it’s going to go, and there’s a lot more confidence and clarity in our predictions. Stay tuned. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/la-nina-is-finishing-an-extremely-unusual-three-year-cycle-heres-how-it-affected-weather-around-the-world-196561">La Niña is finishing an extremely unusual three-year cycle – here's how it affected weather around the world</a>
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<img src="https://counter.theconversation.com/content/201940/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Nandini Ramesh has previously received funding from the Australian Research Council, NASA, and the US Department of Energy. She is a Research Affiliate at the University of Sydney. </span></em></p>After three long years of rainy weather, La Niña is over. But that doesn’t mean El Niño is a certainty. Here’s why.Nandini Ramesh, Senior Research Scientist, Data61, CSIROLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2009022023-03-05T19:20:09Z2023-03-05T19:20:09ZNo, the Fukushima water release is not going to kill the Pacific Ocean<p>Japanese authorities are preparing to release treated radioactive wastewater into the Pacific Ocean, nearly 12 years after the Fukushima nuclear disaster. This will relieve pressure on more than 1,000 storage tanks, creating much-needed space for other vital remediation works. But the plan has attracted controversy. </p>
<p>At first glance, releasing radioactive water into the ocean does sound like a terrible idea. <a href="https://www.greenpeace.org/eastasia/blog/6540/a-quick-read-on-the-radioactive-water-in-fukushima-what-makes-it-different/">Greenpeace</a> feared the radioactivity released <a href="https://www.bbc.com/news/world-asia-54658379">might change human DNA</a>, <a href="https://www.globaltimes.cn/page/202208/1272148.shtml">China</a> and <a href="https://www.koreaherald.com/view.php?ud=20210825001034">South Korea</a> expressed disquiet, while <a href="https://www.forumsec.org/2022/03/14/release-pacific-appoints-panel-of-independent-global-experts-on-nuclear-issues">Pacific Island nations</a> were concerned about further nuclear contamination of the Blue Pacific. <a href="https://doi.org/10.1016/j.ocecoaman.2022.106296">One academic publication</a> claimed the total global social welfare cost could exceed US$200 billion. </p>
<p>But the <a href="https://www.theguardian.com/environment/2023/feb/15/fukushima-japan-insists-release-of-treated-water-is-safe-nuclear-disaster">Japanese government</a>, the International Atomic Energy Agency (<a href="https://www.iaea.org/topics/response/fukushima-daiichi-nuclear-accident/fukushima-daiichi-alps-treated-water-discharge">IAEA</a>) and <a href="https://theconversation.com/fukushima-to-release-wastewater-an-expert-explains-why-this-could-be-the-best-option-198173">independent scientists</a> have declared the planned release to be reasonable and safe. </p>
<p>Based on our collective professional experience in nuclear science and nuclear power, we have reached the same conclusion. Our assessment is based on the type of radioactivity to be released, the amount of radioactivity already present in the ocean, and the high level of independent oversight from the IAEA. </p>
<h2>How much water is there, and what’s in it?</h2>
<p>The storage tanks at Fukushima contain <a href="https://www.tepco.co.jp/en/decommission/progress/watertreatment/alps01/index-e.html">1.3 million tonnes of water</a>, equivalent to around 500 Olympic-sized swimming pools. </p>
<p>Contaminated water is produced daily by ongoing reactor cooling. Contaminated groundwater also collects in the basements of the damaged reactor buildings. </p>
<p>The water is being cleaned by a technology called ALPS, or Advanced Liquid Processing System. This removes the vast majority of the problematic elements. </p>
<p>The ALPS treatment can be repeated until concentrations are below regulatory limits. Independent monitoring by the IAEA will ensure all requirements are met before discharge. </p>
<p>The main radioactive contaminant remaining after treatment is tritium, a radioactive form of hydrogen (H) that is difficult to remove from water (H₂O). There is no technology to remove trace levels of tritium from this volume of water.</p>
<p>Tritium has a half-life of <a href="http://nuclearsafety.gc.ca/eng/resources/fact-sheets/tritium.cfm">12.3 years</a>, meaning 100 years passes before the radioactivity is negligible. It is unrealistic to store the water for such a long time as the volumes are too great. Extended storage also increases the risk of accidental uncontrolled release. </p>
<p>Like all radioactive elements, international standards exist for safe levels of tritium. For liquids, these are measured in Bq per litre, where one Bq (<a href="https://energyeducation.ca/encyclopedia/Becquerel">becquerel</a>) is defined as one radioactive decay per second. At the point of release, the Japanese authorities have chosen a conservative concentration limit of <a href="https://www.nra.go.jp/data/000418886.pdf">1,500Bq per litre</a>, seven times smaller than the World Health Organization’s recommended limit of <a href="https://apps.who.int/iris/bitstream/handle/10665/44584/9789241548151_eng.pdf">10,000Bq per litre</a> for drinking water. </p>
<h2>Why is it acceptable to release tritium into the ocean?</h2>
<p>One surprising thing about radiation is how common it is. Almost everything is radioactive to some degree, including air, water, plants, basements and granite benchtops. Even a long-haul airline flight supplies a few chest X-rays worth of radiation to everyone on board.</p>
<p>In the case of tritium, natural processes in the atmosphere generate <a href="https://www.irsn.fr/EN/Research/publications-documentation/radionuclides-sheets/environment/Pages/Tritium-environment.aspx">50-70</a> <a href="https://physics.nist.gov/cuu/Units/prefixes.html">peta-becquerels (PBq)</a> of tritium every year. This number is difficult to grasp, so it’s helpful to think of it as grams of pure tritium. Using the conversion factor of 1PBq = 2.79g, we see that <a href="https://www.irsn.fr/EN/Research/publications-documentation/radionuclides-sheets/environment/Pages/Tritium-environment.aspx">150-200g</a> of tritium is created naturally each year.</p>
<p>Looking at the Pacific Ocean, around 8.4kg (<a href="https://hal.archives-ouvertes.fr/hal-02336283">3,000PBq</a>) of tritium is already in the water.
By comparison, the total amount of tritium in the Fukushima wastewater is vastly smaller, at around 3g (<a href="https://www.science.org/doi/full/10.1126/science.abc1507">1PBq</a>).</p>
<p>Japanese authorities are not planning to release the water all at once. Instead, just 0.06g (<a href="https://www.nra.go.jp/data/000418886.pdf">22TBq</a>) of tritium is scheduled for release each year. Compared with the radioactivity already present in the Pacific, the planned annual release is a literal drop in the ocean.</p>
<p>The current levels of tritium radioactivity in the Pacific are not of concern, and so the small amount to be added by the Fukushima water won’t cause any harm. </p>
<p>What’s more, tritium only makes a tiny contribution to the total radioactivity of the oceans. Ocean radioactivity is mostly due to potassium, an element <a href="https://www.healthdirect.gov.au/potassium">essential for life</a> and present in all cells. In the Pacific Ocean there is <a href="http://www.waterencyclopedia.com/Po-Re/Radionuclides-in-the-Ocean.html">7.4 million PBq</a> of radioactivity from potassium, more than 1,000 times greater than the amount due to tritium.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/nuclear-power-how-might-radioactive-waste-water-affect-the-environment-159483">Nuclear power: how might radioactive waste water affect the environment?</a>
</strong>
</em>
</p>
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<h2>How do other countries manage the discharge of tritium?</h2>
<p>All nuclear power plants produce some tritium, which is routinely discharged into the ocean and other waterways. The amount generated depends on the type of reactor. </p>
<p>Boiling water reactors, such as at Fukushima, produce relatively low quantities. When Fukushima was operating, the tritium discharge limit was set at <a href="https://www.nra.go.jp/data/000418886.pdf">22TBq per year</a>. That figure is <a href="https://www.nra.go.jp/data/000418886.pdf">far below</a> a level that could cause harm, but is reasonably achievable for this type of power plant. </p>
<p>In contrast, the UK Heysham nuclear power plant has a limit of <a href="https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/932885/Radioactivity_in_food_and_the_environment_2019_RIFE_25.pdf">1300TBq per year</a> because this type of gas-cooled reactor produces a lot of tritium. Heysham has been discharging tritium for 40 years without harm to people or the environment.</p>
<p>Annual tritium discharge at <a href="https://japan-forward.com/china-and-south-korea-too-release-nuclear-plant-wastewater-into-the-oceans/">nearby nuclear power plants</a> far exceeds what is proposed for Fukushima. The Fuqing plant in China discharged 52TBq in 2020, while the Kori plant in South Korea discharged 50TBq in 2018. </p>
<p>Each of these power plants releases more than twice the amount to be released from Fukushima.</p>
<h2>Are there other reasons for not releasing the water?</h2>
<p>Objections to the planned release have been the subject of widespread media coverage. <a href="https://time.com/6250415/fukushima-nuclear-waste-pacific-islands/">TIME</a> magazine recently explained how Pacific Island nations have been grappling for decades with the legacy of Cold War nuclear testing. <a href="https://www.theguardian.com/world/2021/apr/26/if-its-safe-dump-it-in-tokyo-we-in-the-pacific-dont-want-japans-nuclear-wastewater">The Guardian</a> ran an opinion piece from Pacific activists, who argued if the waste was safe, then “dump it in Tokyo, test it in Paris, and store it in Washington, but keep our Pacific nuclear-free”.</p>
<p>But the Pacific has always contained radioactivity, from potassium in particular. The extra radioactivity to be added from the Fukushima water will make the most miniscule of differences. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/fukushima-ten-years-on-from-the-disaster-was-japans-response-right-156554">Fukushima: ten years on from the disaster, was Japan's response right?</a>
</strong>
</em>
</p>
<hr>
<p>Striking a different tone, The Pacific Island Forum <a href="https://www.forumsec.org/2022/03/14/release-pacific-appoints-panel-of-independent-global-experts-on-nuclear-issues/">commissioned a panel of experts</a> to provide independent technical advice and guidance, and help address concerns on the wastewater. The panel was critical of the quantity and quality of data from the Japanese authorities, and advised that <a href="https://www.forumsec.org/2022/11/16/release-expert-advises-deferment-on-japan-fukushima-discharge-dates/">Japan should defer</a> the impending discharge.</p>
<p>While we are sympathetic to the view that the scientific data could be improved, our assessment is the panel is unfairly critical of ocean release. </p>
<p>The main thing missing from the <a href="https://www.forumsec.org/wp-content/uploads/2023/02/Annex-4-Expert-Panel-Memorandum-Summarizing-Our-Views-...-2022-08-11.pdf">report</a> is a sense of perspective. The public seminar from the expert panel, <a href="https://www.youtube.com/watch?v=jzTjCgWlFRU">available on YouTube</a>, presents only a portion of the context we provide above. Existing tritium in the ocean isn’t discussed, and the dominance of potassium is glossed over. </p>
<p>The most reasonable comments regard the performance of ALPS. This is largely in the context of strontium-90 and cesium-137, both of which are legitimate isotopes of concern. </p>
<p>However, the panel implies that the authorities don’t know what is in the tanks, and that ALPS doesn’t work properly. There actually is a lot of public information on both topics. Perhaps it could be repackaged in a clearer way for others to understand. But the inferences made by the panel give the wrong impression. </p>
<p>The most important thing the panel overlooks is that the contaminated water can be repeatedly passed through ALPS until it is safe for release. For some tanks a single pass will suffice, while for others additional cycles are required.</p>
<h2>The big picture</h2>
<p>The earthquake was the <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3222972/">primary environmental disaster</a>, and the planet will be dealing with the consequences for decades. In our view, the release of Fukushima wastewater does not add to the disaster.</p>
<p>It’s easy to understand why people are concerned about the prospect of radioactive liquid waste being released into the ocean. But the water is not dangerous. The nastiest elements have been removed, and what remains is modest compared with natural radioactivity.</p>
<p>We hope science will prevail and Japan will be allowed to continue the recovery process. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/radioactive-waste-isnt-going-away-weve-found-a-new-way-to-trap-it-in-minerals-for-long-term-storage-200255">Radioactive waste isn't going away. We've found a new way to trap it in minerals for long-term storage</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/200902/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Nigel Marks is an Associate Professor in the Physics department at Curtin University. In 1996/97 he worked at the Australian Nuclear Science and Technology (ANSTO) in the reactor division. He has received grants from the Australian Research Council, ANSTO and Los Alamos National Laboratory to study radiation processes in solids.</span></em></p><p class="fine-print"><em><span>Brendan Kennedy is a Professor of Chemistry at the University of Sydney. He is a past president of the Australian Institute of Nuclear Science and Engineering. He is a long time user of advanced nuclear facilities in Europe, USA and Japan.</span></em></p><p class="fine-print"><em><span>Tony Irwin is a Chartered Engineer and Honorary Associate Professor ANU with extensive experience of reactor operations in the UK and Australia. Tony was the first Reactor Manager for ANSTO's OPAL reactor.</span></em></p>An independent assessment of Japan’s plan to release treated radioactive wastewater into the Pacific Ocean, nearly 12 years after the Fukushima nuclear disaster, finds it safe and reasonable.Nigel Marks, Associate Professor of Physics, Curtin UniversityBrendan Kennedy, Professor of Chemistry, University of SydneyTony Irwin, Honorary Associate Professor, Nuclear Reactors and Nuclear Fuel Cycle, Australian National UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1965612023-02-28T06:12:35Z2023-02-28T06:12:35ZLa Niña is finishing an extremely unusual three-year cycle – here’s how it affected weather around the world<figure><img src="https://images.theconversation.com/files/511814/original/file-20230222-16-zc2v88.jpg?ixlib=rb-1.1.0&rect=1288%2C0%2C4184%2C1813&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">El Niño was given its name by Peruvian fishermen.</span> <span class="attribution"><span class="source">Christian Vinces / shutterstock</span></span></figcaption></figure><p>It was anchovy fishermen in Peru who first noticed and named El Niño events in the tropical Pacific <a href="https://baynature.org/article/whys-it-called-el-nino-and-how-did-scientists-figure-out-what-it-is/">hundreds of years ago</a>. Their catches would fluctuate and the largest declines were seen near Christmas when the ocean was at its warmest – they called it <em>El Niño de Navidad</em>, the boy of Christmas. </p>
<p>With a larger network of observations and some <a href="https://www.rmets.org/sites/default/files/classicindia2.pdf">inspired statistical analysis</a>, it became apparent that this decline in fish stocks was part of a Pacific-wide phenomenon including changes in the ocean and atmosphere. This was ENSO, the El Niño-Southern Oscillation. </p>
<p>As part of this analysis it became clear that during El Niño events the Pacific was typically warmer than usual in the east, colder in the west, and the trade winds blowing from east to west were weaker. What also became clear was that there were other times when the winds were stronger and the east was colder and the west was warmer. These periods were named La Niña – the girl – in a nod to their opposite characteristics to El Niño. </p>
<p>El Niño or La Niña conditions typically last for around nine months, beginning in June, peaking in December, before dissipating by April. Historically, La Niña events have been smaller and less noted – the change in the anchovy catches is not as notable as the collapse seen in El Niños so was never remarkable to the Peruvian fishermen. However, for a number of reasons, La Niña is becoming a more noted phenomenon. </p>
<p>During La Niña events, global temperatures tend to be colder and this can explain some of the downward bumps on the otherwise inexorable rise of global temperatures. Last year, 2022, was the third consecutive La Niña year, which is highly unusual and has only occurred <a href="https://earthobservatory.nasa.gov/images/150691/la-nina-times-three">three times</a> since reliable records began in the 1950s. Outside of the tropical Pacific, the effects of La Niña can be just as marked and just as devastating as those of El Niño, which is likely to return in <a href="https://theconversation.com/four-possible-consequences-of-el-nino-returning-in-2023-198105">late 2023</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/511810/original/file-20230222-18-lndbr1.gif?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/511810/original/file-20230222-18-lndbr1.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/511810/original/file-20230222-18-lndbr1.gif?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=300&fit=crop&dpr=1 600w, https://images.theconversation.com/files/511810/original/file-20230222-18-lndbr1.gif?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=300&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/511810/original/file-20230222-18-lndbr1.gif?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=300&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/511810/original/file-20230222-18-lndbr1.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=377&fit=crop&dpr=1 754w, https://images.theconversation.com/files/511810/original/file-20230222-18-lndbr1.gif?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=377&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/511810/original/file-20230222-18-lndbr1.gif?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=377&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">In general, the warmest year of any decade will be an El Niño year, the coldest a La Niña one.</span>
<span class="attribution"><a class="source" href="https://www.climate.gov/media/10685">NOAA / climate.gov</a></span>
</figcaption>
</figure>
<h2>How changes in the tropical Pacific affect the rest of the world</h2>
<p>Climate scientists have been aware of how changes in the atmosphere in one location can be linked to another for many years. These links are termed “teleconnections”. Perhaps the first example of a teleconnection was described <a href="https://www.rmets.org/sites/default/files/classicindia2.pdf">in the 1920s</a> by the physicist Gilbert Walker who noticed that changes in atmospheric pressure in Darwin, on the north coast of Australia, and Tahiti, 8,000kms away in the middle of the Pacific, were linked through, what he termed, the Southern Oscillation. This observation ultimately led to the description of the El Niño/La Niña phenomenon. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/511989/original/file-20230223-658-i6d7r5.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two annotated maps of the Pacific Ocean" src="https://images.theconversation.com/files/511989/original/file-20230223-658-i6d7r5.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/511989/original/file-20230223-658-i6d7r5.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=756&fit=crop&dpr=1 600w, https://images.theconversation.com/files/511989/original/file-20230223-658-i6d7r5.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=756&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/511989/original/file-20230223-658-i6d7r5.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=756&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/511989/original/file-20230223-658-i6d7r5.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=950&fit=crop&dpr=1 754w, https://images.theconversation.com/files/511989/original/file-20230223-658-i6d7r5.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=950&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/511989/original/file-20230223-658-i6d7r5.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=950&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 Pacific in normal and La Niña conditions.</span>
<span class="attribution"><a class="source" href="https://spaceplace.nasa.gov/la-nina/en/">NASA</a></span>
</figcaption>
</figure>
<p>Teleconnection patterns have now been noticed in all regions of the globe. In northern Europe the most well known is the <a href="https://theconversation.com/the-atlantic-is-entering-a-cool-phase-that-will-change-the-worlds-weather-42497">North Atlantic Oscillation</a>, which describes a link between air pressure in a particular area over Iceland and one over the central North Atlantic near to the Azores. Changes can then be linked to changes in the weather over northern Europe and the UK. </p>
<p>These teleconnection patterns exist because the global atmosphere behaves like a drum. If you hit a drum in one location the whole surface vibrates and the note that the drum sounds depends upon how tight the drum skin is. </p>
<p>In this analogy, heating in the tropical atmosphere plays the role of the drum stick and the waves that spread out across the surface are termed <a href="https://oceanservice.noaa.gov/facts/rossby-wave.html">Rossby waves</a>. The “note” that these waves play is determined by the structure of the atmosphere, but rather than skin tension it is the winds and rotation of the earth that determine the pitch of the atmosphere. </p>
<p>The strongest teleconnection from the tropical Pacific and La Niña is within the Pacific Basin. For example La Niña events tend to mean wetter winters in the Pacific Northwest of the US. </p>
<p>However, Rossby waves can reach all the way across North America and into the North Atlantic, where they can start to affect the weather by tweaking the <a href="https://theconversation.com/why-the-uk-has-only-had-one-named-storm-so-far-this-winter-an-expert-explains-200364">high-altitude jet stream</a> which can in turn affect the storms that are responsible for much of the UK’s winter rain. </p>
<p>Because the behaviour of Rossby waves depends upon the winds in the atmosphere, La Niña’s influence on the North Atlantic is not the same in all seasons. In late winter the Rossby waves from La Niña tend to intensify and shift the Atlantic jet stream towards the North Pole, causing more storms to hit the UK and with them increase the rainfall. </p>
<p>It’s harder to directly link the two in early winter, since in this season the Rossby waves interact with winds that are more affected by the climate state of the tropical Atlantic. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/511822/original/file-20230222-18-5kmt0m.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Lighthouse in a storm" src="https://images.theconversation.com/files/511822/original/file-20230222-18-5kmt0m.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/511822/original/file-20230222-18-5kmt0m.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/511822/original/file-20230222-18-5kmt0m.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/511822/original/file-20230222-18-5kmt0m.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/511822/original/file-20230222-18-5kmt0m.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/511822/original/file-20230222-18-5kmt0m.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/511822/original/file-20230222-18-5kmt0m.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 UK is stormier and rainier in late winter during La Niña years (pictured: a lighthouse in Porthcawl, Wales).</span>
<span class="attribution"><span class="source">steved_np3 / shutterstock</span></span>
</figcaption>
</figure>
<h2>An uncertain future</h2>
<p>It’s hard to know exactly what climate change will mean for El Niños and La Niñas. Average sea surface temperature across the Pacific will increase, but that is less important to the generation of these weather patterns than the difference in surface temperature between west and east Pacific about which there is a lot less certainty (in part because the surface temperature in the eastern Pacific is always heavily influenced by the upwelling of deeper colder waters).</p>
<p>Computer programs that model the climate suggest the Pacific’s east-west temperature difference will diminish in future, <a href="https://www.nature.com/articles/s41612-022-00301-2">favouring EL Niños</a> which tends to mean more <a href="https://theconversation.com/four-possible-consequences-of-el-nino-returning-in-2023-198105">droughts in Australia</a> and other severe weather across the Pacific and beyond. However, the past two decades of enhanced temperature differences and prolonged La Niña events <a href="https://journals.ametsoc.org/view/journals/clim/35/14/JCLI-D-21-0648.1.xml">suggest otherwise</a>. The recent three-year La Niña is therefore very interesting, though it’s too soon to draw any firm conclusions.</p>
<p>Changes in the teleconnections are <a href="https://journals.ametsoc.org/view/journals/clim/36/6/JCLI-D-22-0275.1.xml">equally uncertain</a>. Therefore, uncertain changes in the teleconnections on top of uncertain changes in La Niña and El Niño add up to an uncertain outlook for the future. </p>
<hr>
<figure class="align-right ">
<img alt="Imagine weekly climate newsletter" src="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p class="fine-print"><em><span>William Roberts receives funding from UKRI.</span></em></p><p class="fine-print"><em><span>Jayasankar Pillai receives funding from European Union Horizon 2020 programme</span></em></p>The Pacific Ocean climate pattern is the opposite of El Niño.William Roberts, Assistant Professor, Climate Science, Northumbria University, NewcastleJayasankar Pillai, Research Fellow, Geography and Environmental Sciences, Northumbria University, NewcastleLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2003642023-02-23T17:47:02Z2023-02-23T17:47:02ZWhy the UK has only had one named storm so far this winter – an expert explains<p><a href="https://www.metoffice.gov.uk/about-us/press-office/news/weather-and-climate/2023/storm-otto-named-by-danish-met-service#:%7E:text=A%20low%2Dpressure%20system%20which,75mph%20to%20some%20northern%20areas.">Storm Otto</a>, which was named by the Danish Meteorological Institute, hit Scotland and north-east England last Friday (February 17 2023) with wind gusts of over 80mph, disrupting power to 61,000 homes. </p>
<p>Otto was the first named storm of the UK’s current winter storm season and the first to hit the country’s shores since <a href="https://www.metoffice.gov.uk/binaries/content/assets/metofficegovuk/pdf/weather/learn-about/uk-past-events/interesting/2022/2022_01_storms_dudley_eunice_franklin_r1.pdf">storms Dudley, Eunice and Franklin</a> last February. Over the course of a week, these three storms barrelled in from the North Atlantic causing wind and flood damage worth over <a href="https://www.perils.org/losses">€3.7 billion (£3.2 billion) in insured losses</a> across Europe. </p>
<p>The UK has seen only a few notable instances of stormy weather so far this winter. For example, heavy rainfall in the first few weeks of January led to <a href="https://www.itv.com/news/westcountry/2023-01-19/pictures-show-scale-of-flooding-on-somerset-levels">flooding on the Somerset Levels</a>. But this storm was not intense enough to be named. This happens only when a <a href="https://www.metoffice.gov.uk/weather/warnings-and-advice/uk-storm-centre/index">storm has the potential</a> to be severe enough to cause an amber or red warning. </p>
<p>But storms are a common feature of winters in the UK. Since the current naming scheme started in 2016, between five and ten named storms have hit the UK each winter. So what’s been going on with the weather this year and why did the UK wait such a long time between named storms? </p>
<h2>Variable UK weather</h2>
<p>Chance can always play a role, particularly in the case of UK weather. </p>
<p>A narrow band of strong winds in the upper atmosphere, known as the jet stream, steers storms that originate over the North Atlantic towards Europe and the UK. But the jet stream itself is naturally very variable and can shift in position and strength. This can cause the UK’s weather to vary a lot from year to year. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/Lg91eowtfbw?wmode=transparent&start=4" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">What is the jet stream and how does it affect our weather?</span></figcaption>
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<p>The UK has therefore gone long periods without large storms before. For example, the <a href="https://digital.nmla.metoffice.gov.uk/">winter of 1985-86</a> was relatively quiet and was marked by storms at either end of the season with only one strong storm in January.</p>
<h2>La Niña conditions</h2>
<p>A global weather phenomenon called La Niña is also likely to have contributed to this year’s weather. La Niña is one phase of the <a href="https://www.climate.gov/news-features/blogs/enso/what-el-ni%C3%B1o%E2%80%93southern-oscillation-enso-nutshell">El Niño Southern Oscillation</a> and is characterised by relatively cool sea surface temperatures in tropical areas of the Pacific. This winter, sea surface temperatures in the tropical Pacific Ocean have been <a href="https://iri.columbia.edu/our-expertise/climate/forecasts/enso/current/">nearly 1°C cooler</a> than average. </p>
<p>La Niña can influence the weather experienced in the northern hemisphere. Cooler sea surface temperatures in the Pacific shift the position of rainfall in the tropics. These changes then propagate into the mid-latitudes, almost like ripples on a pond, and influence the position of the jet stream over the North Atlantic.</p>
<p>The impact of La Niña on weather in the North Atlantic is different in early and late winter. </p>
<p>Early in the season, La Niña tends to <a href="https://journals.ametsoc.org/view/journals/clim/31/11/jcli-d-17-0716.1.xml">shift the jet stream to the south</a>, steering storms that would normally hit the UK towards southern Europe. This may partly explain the bouts of stormy weather that brought flooding to Portugal, Spain and Italy in November and December of 2022. On December 7, <a href="https://www.efas.eu/en/news/floods-portugal-and-spain-december-2022">flash flooding</a> swept through the streets of Lisbon, the capital of Portugal, after 82.3mm of rain fell in 24 hours.</p>
<h2>Sudden stratospheric warming</h2>
<p>Later in the winter season, La Niña tends to shift the jet stream back towards the north and should bring stormier weather to the UK. During a typical winter, cooling air causes a vortex of westerly winds to form in the stratosphere, 10-50km above the Arctic. </p>
<p>The <a href="https://www.metoffice.gov.uk/weather/learn-about/weather/atmosphere/polar-vortex#:%7E:text=What%20is%20the%20Polar%20Vortex,about%20it%20for%20many%20years.">stratospheric polar vortex</a>, as it is called, remains remarkably stable most winters. But some years, the polar vortex slows and breaks up suddenly, causing the stratospheric air over the Arctic to warm rapidly. Called a sudden stratospheric warming, such an event has been occurring since <a href="https://blog.metoffice.gov.uk/2023/02/07/are-we-expecting-a-sudden-stratospheric-warming/">mid-February</a>.</p>
<p>These <a href="https://www.metoffice.gov.uk/weather/learn-about/weather/types-of-weather/wind/sudden-stratospheric-warming">sudden stratospheric warmings</a>, and the rapid slow down of the polar vortex, causes the North Atlantic jet stream below to slow down and meander. In some cases, sudden stratospheric warming can create a large area of high pressure over the North Atlantic and Scandinavia, bringing a spell of dry weather to northern Europe. This happened following the last <a href="https://www.rmets.org/metmatters/polar-vortex-sudden-stratospheric-warmings-and-beast-east">sudden stratospheric warming</a> event in January 2021. </p>
<p>But the effect of a sudden stratospheric warming on the UK’s weather can vary. The European blocking associated with sudden stratospheric warming can sometimes bring in freezing air from Europe, increasing the risk of snow. This was the case in late February 2018, where a sudden stratospheric warming drew winds from the Eurasian continent, causing storms and severe snowfall to affect much of the UK – known as the <a href="https://www.rmets.org/metmatters/beast-east-bites-uk">“beast from the east”</a>.</p>
<p>Although the UK might expect some colder weather in the next few weeks, there is no indication in current weather forecasts that this year’s sudden stratospheric warming will lead to the extreme cold weather seen in 2018.</p>
<p>This winter has been less stormy than usual. Yet, the UK relies on rain from North Atlantic storms to refill its rivers, reservoirs and aquifers. This is particularly important this year given last year’s exceptionally hot and dry summer that lead to drought conditions in much of the UK. </p>
<p>Despite only having one named storm, <a href="https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/1136621/Monthly_water_situation_report_for_England_January_2023.pdf">rainfall across most of the UK</a> has fortunately been around or above average since October. This has helped to replenish water resources. But even then, <a href="https://www.gov.uk/government/news/one-hot-dry-spell-away-from-drought-returning-this-summer-national-drought-group-warns">East Anglia and Cornwall</a> remain in drought. So to top up the UK’s water resources and banish the spectre of a 2023 drought, a few more moderate storms over the next few months would be very welcome.</p>
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<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">
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<p class="fine-print"><em><span>Len Shaffrey receives funding from the Natural Environment Research Council and the European Commission's Horizon Europe funding scheme.</span></em></p>An expert explains why the UK’s winter has been relatively calm.Len Shaffrey, Professor of Climate Science, National Centre for Atmospheric Science, University of ReadingLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1981052023-01-26T16:02:34Z2023-01-26T16:02:34ZFour possible consequences of El Niño returning in 2023<figure><img src="https://images.theconversation.com/files/506579/original/file-20230126-20-pu1ru1.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C3872%2C2590&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Dry conditions are likely to resume in northeastern Brazil.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/livestock-cattle-being-driven-by-dirt-2143454947">Cacio Murilo/Shutterstock</a></span></figcaption></figure><p>Every two to seven years, the equatorial Pacific Ocean gets up to 3°C warmer (what we know as an El Niño event) or colder (La Niña) than usual, triggering a cascade of effects felt around the world. This cycle is called the El Niño Southern Oscillation (ENSO) because every El Niño is naturally followed by a La Niña and vice versa, with some months of neutral conditions in between events. The change in sea surface temperature associated with ENSO events might seem marginal, but it is more than enough to disrupt weather patterns globally and even the large-scale circulation of air in the polar stratosphere 8km above the Earth.</p>
<p>It is not surprising for La Niña conditions to last two consecutive years, but a three-year La Niña, which the world has had since 2020, is more rare. The US National Oceanic and Atmospheric Administration (NOAA) has <a href="https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/lanina/enso_evolution-status-fcsts-web.pdf">reported</a> that the equatorial Pacific Ocean will return to its neutral state between March and May of 2023, and it is likely that El Niño conditions will develop during the northern hemisphere’s autumn and winter.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/506382/original/file-20230125-18-cfktl7.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A bar chart depicting a shift from La Niña to El Niño over the course of 2023." src="https://images.theconversation.com/files/506382/original/file-20230125-18-cfktl7.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/506382/original/file-20230125-18-cfktl7.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=381&fit=crop&dpr=1 600w, https://images.theconversation.com/files/506382/original/file-20230125-18-cfktl7.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=381&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/506382/original/file-20230125-18-cfktl7.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=381&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/506382/original/file-20230125-18-cfktl7.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=479&fit=crop&dpr=1 754w, https://images.theconversation.com/files/506382/original/file-20230125-18-cfktl7.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=479&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/506382/original/file-20230125-18-cfktl7.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=479&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Probability of El Niño (red), La Niña (blue) or ENSO-neutral conditions developing during the coming months.</span>
<span class="attribution"><a class="source" href="https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/lanina/enso_evolution-status-fcsts-web.pdf">Climate Prediction Center/NOAA</a>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Given the strong influence of ENSO on global patterns of precipitation and temperature, scientists keep a close watch on the status of the tropical Pacific to provide the best possible information. So what can the world expect from the next El Niño event?</p>
<h2>1. Likelihood of exceeding 1.5°C</h2>
<p>During an El Niño, the ocean transfers some of that excess heat and moisture to the atmosphere, as when you cook pasta and your kitchen gets steamy. On top of the global warming trend, a strong El Niño can add up to 0.2°C to the average temperature of the Earth. The hottest year on record was 2016, during a particularly strong El Niño. A La Niña year can also break heat records, as the warming trend imposed by the increasing accumulation of greenhouse gases in the atmosphere can mask the cooling effect of natural processes.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/506530/original/file-20230126-11748-v3hf40.gif?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A series of bar charts depicting annual average surface temperatures, grouped by decade, from 1950 to 2021. The warmest and coldest years of each decade are topped with circles: red for El Niño-influenced years and blue for La Niña years." src="https://images.theconversation.com/files/506530/original/file-20230126-11748-v3hf40.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/506530/original/file-20230126-11748-v3hf40.gif?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=300&fit=crop&dpr=1 600w, https://images.theconversation.com/files/506530/original/file-20230126-11748-v3hf40.gif?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=300&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/506530/original/file-20230126-11748-v3hf40.gif?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=300&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/506530/original/file-20230126-11748-v3hf40.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=377&fit=crop&dpr=1 754w, https://images.theconversation.com/files/506530/original/file-20230126-11748-v3hf40.gif?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=377&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/506530/original/file-20230126-11748-v3hf40.gif?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=377&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">As the world has warmed, the hottest years have occurred during El Niño events.</span>
<span class="attribution"><span class="source">NOAA Climate/NOAA National Centers for Environmental Information</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Since the planet has already warmed by around 1.2°C relative to pre-industrial times and El Niño adds some extra heat to the atmosphere, it’s possible that Earth’s rising temperature will temporarily exceed the <a href="https://theconversation.com/after-cop27-all-signs-point-to-world-blowing-past-the-1-5-degrees-global-warming-limit-heres-what-we-can-still-do-about-it-195080">1.5°C threshold</a> of the Paris agreement some time after the peak of the El Niño in 2024, though it is too early to know how strong this next event will be.</p>
<h2>2. More heat, drought and fires in Australia</h2>
<p>Australia has had three years of above average rainfall due to prolonged La Niña conditions that brought severe floods, especially in the east. During El Niño, scientists expect the opposite: less rain, higher temperatures and increased fire risk, especially during winter and spring in the southern hemisphere.</p>
<p>As the globe heats up, some regions are warming faster than others. A good example is <a href="https://www.nature.com/articles/s41467-021-27225-4">Australia</a>, which is 1.4°C hotter now than in the early 20th century. Every year, the area of the continent scorched by wildfires increases, fuelled by a dry trend induced by climate change. This occurs despite the anomalous wet years that Australia has experienced during the recent La Niña event. The underlying influence of climate change makes the country extremely vulnerable to the effects of an El Niño.</p>
<figure class="align-center ">
<img alt="The undergrowth burns in an Australian eucalypt forest." src="https://images.theconversation.com/files/506575/original/file-20230126-24-p45etq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/506575/original/file-20230126-24-p45etq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/506575/original/file-20230126-24-p45etq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/506575/original/file-20230126-24-p45etq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/506575/original/file-20230126-24-p45etq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/506575/original/file-20230126-24-p45etq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/506575/original/file-20230126-24-p45etq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Heatwaves and wildfires could become more frequent and severe in 2023.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/fire-undergrowth-eucalypt-forest-flames-dense-750956152">Metriognome/Shutterstock</a></span>
</figcaption>
</figure>
<h2>3. Slower carbon uptake in South America</h2>
<p>South America is where the effects of ENSO were first documented by Peruvian fishermen centuries ago. Given the proximity to the equatorial Pacific Ocean, South American weather is significantly disrupted every time an El Niño event occurs, with flooding on the west coasts of Peru and Ecuador and drought in the Amazon and northeast, where the consequences of crop failures can reverberate across the continent.</p>
<p>During El Niño events, the fall in precipitation and rise in temperature in Colombia has been linked to outbreaks of diseases spread by insects, such as <a href="http://users.clas.ufl.edu/prwaylen/Geo3280articles/Poveda.pdf">malaria and dengue fever</a>. Higher temperatures during El Niño boost the rates at which mosquitoes breed and bite.</p>
<p>Elsewhere during an El Niño, the Amazon rainforest dries and vegetation growth slows so that less CO₂ is absorbed from the atmosphere, a trend <a href="https://journals.ametsoc.org/view/journals/clim/14/21/1520-0442_2001_014_4113_tccrte_2.0.co_2.xml">repeated</a> in the tropical forests of Africa, India and Australia.</p>
<figure class="align-center ">
<img alt="A scientist inspecting a tree in a tropical forest." src="https://images.theconversation.com/files/506532/original/file-20230126-14416-41uyq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/506532/original/file-20230126-14416-41uyq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/506532/original/file-20230126-14416-41uyq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/506532/original/file-20230126-14416-41uyq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/506532/original/file-20230126-14416-41uyq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/506532/original/file-20230126-14416-41uyq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/506532/original/file-20230126-14416-41uyq.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">Scientists in 2019 studying the damage from Amazon forest fires that burned during the 2015/16 El Niño.</span>
<span class="attribution"><span class="source">Marizilda Cruppe/Rede Amazônia Sustentável</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>4. Cold winters in northern Europe</h2>
<p>The balance between high pressure over the Azores and low pressure over Iceland determines where rain goes in Europe during winter by pushing the jet stream – a band of strong eastward winds that carries rain across the Atlantic – north or south. During El Niño winters, both pressure centres lose strength, and the jet stream brings wetter conditions to southern Europe. </p>
<p>The largest effect is observed in northern Europe, however, where winters become drier and colder. A frosty 2023-24 winter season is likely if El Niño ramps up sufficiently by then. As a result of global warming, scientists expect El Niño’s influence over the North Atlantic and northern European winter will <a href="https://www.frontiersin.org/articles/10.3389/fclim.2022.941055/full">strengthen</a>.</p>
<p>Understanding the intricacies of the climate system is similar to trying to assemble a <a href="https://www.jstor.org/stable/1691792#metadata_info_tab_contents">big jigsaw puzzle</a>. The oceans talk to each other, and to the atmosphere, which at the same time feeds back to the ocean. Scientists are still unsure how El Niño will behave in the future, but its effects will probably be amplified by climate change in different regions of the world.</p>
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<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">
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<p class="fine-print"><em><span>Paloma Trascasa-Castro receives funding from the Natural Environment Research Council (NERC).</span></em></p>From bushfires in Australia to insect-borne disease outbreaks in Colombia.Paloma Trascasa-Castro, PhD Candidate in Climate Science, Barcelona Supercomputing Centre, University of LeedsLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1981732023-01-23T06:06:21Z2023-01-23T06:06:21ZFukushima to release wastewater – an expert explains why this could be the best option<p>Over ten years ago, a tsunami <a href="https://world-nuclear.org/information-library/safety-and-security/safety-of-plants/fukushima-daiichi-accident.aspx">triggered a disaster</a> at the Fukushima Daiichi Nuclear Power Plant on Japan’s east coast. After the accident, large amounts of radioactivity contaminated the ocean leading to the imposition of a <a href="https://link.springer.com/chapter/10.1007/978-981-13-3218-0_18">marine exclusion zone and huge reputational damage</a> to the regional fishing industry. </p>
<p>Huge volumes of contaminated water have accumulated on the site since. Water was needed to cool the damaged reactors and groundwater that became contaminated as it infiltrated the site had to be pumped out and stored. Over 1,000 tanks have been built on site to store <a href="https://www.tepco.co.jp/en/decommission/progress/watertreatment/alps01/index-e.html#amount">over a million tonnes</a> of radioactive water.</p>
<p>But the site is running out of storage space and the tanks could leak, particularly in the event of an earthquake or a typhoon. So the Japanese authorities have given the site permission to release the stored radioactive water through a pipeline to the Pacific Ocean.</p>
<p>As an environmental scientist, I have worked on the impacts of radioactive pollutants in the environment for more than 30 years. I think that releasing the wastewater is the best option.</p>
<h2>Contaminated water</h2>
<p>Before it is stored, the wastewater produced at Fukushima is treated to remove almost all of the radioactive elements. These include <a href="https://www.epa.gov/radiation/radionuclide-basics-cobalt-60">cobalt 60</a>, <a href="https://www.epa.gov/radiation/radionuclide-basics-strontium-90">strontium 90</a> and <a href="https://www.epa.gov/radiation/radionuclide-basics-cesium-137">caesium 137</a>. But <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/tritium">tritium</a> – a radioactive form of hydrogen – is left behind.</p>
<p>When one of the hydrogen atoms in water is replaced by tritium, it forms radioactive tritiated water. Tritiated water is chemically identical to normal water, which makes separating it from wastewater expensive, energy intensive and time consuming. A <a href="https://www.meti.go.jp/english/earthquake/nuclear/decommissioning/pdf/20200210_alps.pdf">review</a> of tritium separation technologies in 2020 found that they are unable to process the huge volumes of water required.</p>
<p>But as radioactive elements go, tritium is relatively benign and its existence as tritiated water reduces its environmental impact. Chemically identical to normal water, tritiated water passes through organisms like water does and so does not strongly accumulate in the bodies of living things.</p>
<p>Tritiated water has a <a href="https://hal-normandie-univ.archives-ouvertes.fr/hal-02433412/file/Fi%C3%A9vet_2013_Transfer%20of%20tritium%20released%20into%20the%20marine%20environment%20by%20French%20nuclear%20facilities%20bordering%20the%20English%20Channel.pdf">bioaccumulation factor of about one</a>. This means exposed animals would have roughly the same concentration of tritium in their bodies as the surrounding water.</p>
<p>By comparison, radioactive caesium 137, released in large quantities after Fukushima and from the UK’s Sellafield nuclear site in the 1960s and 70s, has a bioaccumulation factor in marine environments of <a href="https://www-pub.iaea.org/MTCD/Publications/PDF/TRS422_web.pdf">roughly 100</a>. Animals tend to have around 100 times more radiocaesium than in the surrounding water because caesium magnifies up the food chain. </p>
<h2>Low radiation dose</h2>
<p>When tritium decays, it gives off a beta particle (a fast-moving electron that can damage DNA if ingested). But tritium’s beta particle is not very energetic. A person would need to ingest a lot of it to be given a significant radiation dose.</p>
<p>The World Health Organization’s <a href="https://cdn.who.int/media/docs/default-source/wash-documents/water-safety-and-quality/dwq-guidelines-4/gdwq4-with-add1-chap9.pdf?sfvrsn=6fc78cae_3">drinking water standard</a> for tritium is 10,000 Becquerels (Bq) per litre. This is several times higher than the planned concentration of the discharge water at Fukushima.</p>
<p>The difficulty of separating tritium from wastewater and its limited environmental impact is the reason nuclear facilities around the world have been releasing it into the sea for decades. The Fukushima Daiichi site is planning to release about 1 Petabecquerel (PBq – 1 with 15 zeros after it) of tritium at a rate of <a href="https://www.tepco.co.jp/en/hd/newsroom/press/archives/2021/pdf/211117e0102.pdf">0.022 PBq per year</a>.</p>
<p>This sounds like a huge number but globally, <a href="https://www.irsn.fr/EN/Research/publications-documentation/radionuclides-sheets/environment/Pages/Tritium-environment.aspx">50-70 PBq of tritium</a> is produced naturally in our atmosphere by cosmic rays each year. While annually, the Cap de la Hague nuclear fuel reprocessing site in northern France releases roughly <a href="https://hal-normandie-univ.archives-ouvertes.fr/hal-02433412/file/Fi%C3%A9vet_2013_Transfer%20of%20tritium%20released%20into%20the%20marine%20environment%20by%20French%20nuclear%20facilities%20bordering%20the%20English%20Channel.pdf">10 PBq</a> of tritium into the English Channel.</p>
<p>Significantly higher rates of release from Cap de la Hague than planned at Fukushima have <a href="https://www.irsn.fr/EN/publications/technical-publications/Documents/IRSN_BR%202015-2017_V1_EN_web.pdf">shown no evidence</a> of significant environmental impacts and doses to people are low. </p>
<h2>Safe release</h2>
<p>But the release of radioactive water must be done properly.</p>
<p><a href="https://www.tepco.co.jp/en/hd/newsroom/press/archives/2021/pdf/211117e0102.pdf">Japanese studies</a> estimate that the wastewater will be diluted from hundreds of thousands of Bq per litre of tritium in the storage tanks to 1,500 Bq per litre in discharge water. <a href="https://www.iaea.org/sites/default/files/report_1_review_mission_to_tepco_and_meti.pdf">Diluting the wastewater</a> before it is released will reduce the radiation dose to people. </p>
<p>The radiation dose to people is measured in sieverts, or millionths of sieverts (microsieverts), where a dose of 1,000 microsieverts represents a one in 25,000 chance of dying early from cancer. The <a href="https://www.tepco.co.jp/en/hd/newsroom/press/archives/2021/pdf/211117e0102.pdf">maximum estimated dose</a> from Fukushima’s discharged water will be 3.9 microsieverts per year. This is much lower than the 2,400 microsieverts people receive from natural radiation on average each year. </p>
<p>The Japanese authorities must also ensure that there are not significant amounts of “organically bound tritium” in the released water. This is where a tritium atom replaces ordinary hydrogen in an organic molecule. The organic molecules containing tritium can then be absorbed in to sediments and ingested by marine organisms</p>
<p>In the mid-1990s, organic molecules containing tritium were released from the Nycomed-Amersham pharmaceuticals plant in Cardiff Bay, Wales. The release led to bioaccumulation factors as <a href="https://www.sciencedirect.com/science/article/abs/pii/S0025326X0100039X?casa_token=rU1zVGEdYYMAAAAA:rO5YwPfC1BWdCjRSA2hjh38Vm0LPcBd79Gg42kaVhE76hroYTnj7zEaLPRyiXmn32TGX4yqK">high as 10,000</a>.</p>
<p>Treatment for other more dangerous radioactive elements also tends to <a href="https://www.meti.go.jp/earthquake/nuclear/pdf/140424/140424_02_008.pdf">leave small amounts</a> of these elements in the wastewater. The wastewater stored at Fukushima will be <a href="https://www.tepco.co.jp/en/decommission/progress/watertreatment/oceanrelease/index-e.html">re-treated</a> to make sure levels of these elements are low enough to be safe for discharge.</p>
<p>On the grand scale of the environmental problems we face, the release of wastewater from Fukushima is a relatively minor one. But it is likely to do more reputational damage to Fukushima’s beleaguered fishing industry. This will not be helped by the political and media furore that’s likely to surround new releases of radioactive water to the Pacific Ocean.</p><img src="https://counter.theconversation.com/content/198173/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>In 2008-2013, The University of Portsmouth was paid a total of about £25k for Jim Smith's consultancy for a range of clients including Horizon Nuclear Power and the Japan Atomic Energy Agency for risk assessment work. In 2012-17 he was awarded a grant from the UK Natural Environment Research Council, partly funded by Radioactive Waste Management, for research at Chernobyl. He currently has no relevant external funding and does not do paid external consultancy.</span></em></p>Japan’s Fukushima Daiichi Nuclear Power Plant is set to release radioactive wastewater into the Pacific Ocean – but the cause for concern is minimal.Jim Smith, Professor of Environmental Science, University of PortsmouthLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1968972023-01-10T04:19:04Z2023-01-10T04:19:04ZEngland may be set to flood at the end of winter – here’s why<figure><img src="https://images.theconversation.com/files/503393/original/file-20230106-12-u03vc8.jpg?ixlib=rb-1.1.0&rect=11%2C0%2C3947%2C2635&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">England may flood in February.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/malton-england1127-young-family-being-rescued-1162753714">Steve Allen/Shutterstock</a></span></figcaption></figure><p>Within the space of a week in February 2022, England and Wales were affected by <a href="https://www.metoffice.gov.uk/binaries/content/assets/metofficegovuk/pdf/weather/learn-about/uk-past-events/interesting/2022/2022_01_storms_dudley_eunice_franklin_r1.pdf">three severe storms</a> (Dudley, Eunice and Franklin). Persistent heavy rain led to the flooding of around 400 properties and severe flood warnings were issued for several major rivers, including the River Severn. Now, the UK Met Office is <a href="https://www.theguardian.com/environment/2022/nov/07/met-office-predicts-severe-flooding-across-england-in-february">predicting</a> that England is again set to experience severe flooding in February 2023 – a prediction the forecasters attribute to a global weather phenomenon called La Niña.</p>
<p>El Niño and La Niña are the two separate phases of the <a href="https://www.climate.gov/news-features/blogs/enso/what-el-ni%C3%B1o%E2%80%93southern-oscillation-enso-nutshell">El Niño southern oscillation</a> (ENSO). This is the name given to the phenomenon of irregular <a href="https://earthobservatory.nasa.gov/global-maps/MYD28M#:%7E:text=Sea%20surface%20temperatures%20have%20a,2%20to%203%20degrees%20Celsius.">annual variations</a> in sea surface temperatures (by as much as 3°C), air pressure and rainfall across the Pacific Ocean. A La Niña event is characterised by significantly lower sea surface temperatures in areas of the Pacific.</p>
<p>Further research is needed into the effects of global weather systems on winter weather in the northern hemisphere. But wide variations in Pacific sea surface temperatures can set off a chain reaction of extreme weather across the world. La Niña can destabilise atmospheric pressures in the Atlantic Ocean and lead to heavy rainfall in western Europe and the southern US. </p>
<p>But other factors may also contribute to the Met Office’s flood prediction. These include the long-term impacts of climate change and urban development in areas prone to flooding.</p>
<h2>Global weather patterns</h2>
<p>During a La Niña event, cooler water decreases the temperature of the air immediately above the sea and <a href="https://sciencing.com/temperature-affect-barometric-pressure-5013070.html">causes it to sink</a>. This creates large areas of low pressure in the Pacific Ocean which generally lead to increased rainfall in the surrounding region. </p>
<p>However, these extensive low pressure areas force pools of high pressure northwards towards Europe. This manifests initially as drier and colder weather conditions in the UK as the seasonal rains brought by low pressure rain-bearing depressions from the Atlantic are blocked by persistent high pressure conditions. </p>
<p>The first half of December 2022, for instance, marked the coldest start to a UK winter since 2010. The <a href="https://blog.metoffice.gov.uk/2022/12/30/cold-december-concludes-warmest-year-on-record-for-uk/">monthly temperature average</a> was 1.3°C lower than the December average between 1991 and 2020.</p>
<p>Powerful storms are instead likely later in the season. As the high pressure recedes and La Niña shifts jet stream patterns northwards, the usual pattern of westerly depressions is allowed to resume. Cooler-than-usual Pacific ocean temperatures in recent months have prompted scientists to predict that there is a <a href="https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/ensodisc.shtml">76% chance</a> that La Niña will persist until the end of February 2023. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/tIJBtdagj2E?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">La Niña explained.</span></figcaption>
</figure>
<h2>Favourable conditions</h2>
<p>La Niña conditions may result in heavy late winter rainfall. But the UK is experiencing increasingly extreme weather conditions all year round. The long-term impacts of this could create conditions favourable for flooding. </p>
<p>Southern England faces long periods of drought each summer. Last year, the Anglian, Thames and Wessex water supply regions all recorded their <a href="https://www.ceh.ac.uk/news-and-media/blogs/why-we-are-still-drought-despite-recent-rain#:%7E:text=Summer%202022%20(June%2DAugust),shown%20in%20the%20plot%20below">fifth-driest summer</a> since 1836. </p>
<p>This has increased the risk of flooding as ground surfaces become less permeable to rainfall infiltration. Despite recent low intensity rainfall, the risk of flooding in the areas affected by drought may still be high. Cold temperatures, like those experienced in December, may also return later this winter and further reduce the ground’s capacity to absorb water. </p>
<p>Underground, chalk aquifers dominate central and southern parts of England. These aquifers, like sponges, have a finite capacity to accept and transmit fast flowing water. Heavy rainfall may therefore be forced over land where it can flow rapidly. <a href="https://nora.nerc.ac.uk/id/eprint/14085/1/1_Mansour_HydrologicalProcesses_Submitted.pdf">Research</a> indicates that above ground, water can flow at up to 100 times the speed of its flow through aquifer rock. </p>
<p>This water flows into sewers and rivers and can overwhelm their natural or operational capacities. Rivers then break their banks and cause flooding. </p>
<figure class="align-center ">
<img alt="A fence submerged in a flooded river." src="https://images.theconversation.com/files/503394/original/file-20230106-18-qjqw2y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/503394/original/file-20230106-18-qjqw2y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/503394/original/file-20230106-18-qjqw2y.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/503394/original/file-20230106-18-qjqw2y.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/503394/original/file-20230106-18-qjqw2y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/503394/original/file-20230106-18-qjqw2y.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/503394/original/file-20230106-18-qjqw2y.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">England’s environmental conditions are favourable for flooding.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/submerged-wooden-fence-on-river-heavy-1656383137">Ceri Breeze/Shutterstock</a></span>
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<h2>Humans offer little help</h2>
<p>Several other factors also increase the likelihood that heavy rainfall this winter will cause parts of England to flood. </p>
<p>Over half of England’s major urban flooding events in early 2022 were driven by <a href="https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/292928/geho0609bqds-e-e.pdf">underground blockages</a> of dated sewerage systems. Their insufficient capacity caused them to fast become overwhelmed by debris floating in floodwater. </p>
<p>Some UK cities, such as Hull, Bristol and parts of London have also been developed on river floodplains. Land on floodplains is often cheap, flat and, as such, easy to build on. But this makes these cities prone to flooding. Flood risk mapping has revealed that <a href="https://www.gov.uk/check-flooding">19% of Gloucester</a>, a city in the southwest of England, is at risk of regular flooding.</p>
<p>Climate models are now predicting climatic changes and global weather patterns with <a href="https://climate.nasa.gov/news/2943/study-confirms-climate-models-are-getting-future-warming-projections-right/">increased accuracy</a>. But mitigating their environmental impacts often proves challenging.</p>
<p>England requires extensive infrastructure changes to reduce the threat of flooding. One option is to prohibit the construction of housing on floodplains. However, urban planning approaches such as this involve overcoming legal and regulatory barriers. </p>
<p>Another approach would be to improve sewerage capacity to account for population growth and its associated pressure on water use. Yet the completion of large infrastructural measures takes time. Various different stakeholders, including the public, must be consulted, while competing designs have to be assessed by experts and their impact modelled. It took <a href="https://www.gov.uk/guidance/the-thames-barrier">15 years</a>, for example, for London’s Thames Barrier to be completed following its initial conception. </p>
<figure class="align-center ">
<img alt="The Thames Barrier, stretching across the River Thames in London." src="https://images.theconversation.com/files/503395/original/file-20230106-10513-wqbkru.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/503395/original/file-20230106-10513-wqbkru.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/503395/original/file-20230106-10513-wqbkru.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/503395/original/file-20230106-10513-wqbkru.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/503395/original/file-20230106-10513-wqbkru.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/503395/original/file-20230106-10513-wqbkru.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/503395/original/file-20230106-10513-wqbkru.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">London’s Thames Barrier has been in operation since 1984.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/london-aug-4-thames-barrier-tidal-149443685">BBA Photography/Shutterstock</a></span>
</figcaption>
</figure>
<p>Flood management measures also require the political will for implementation. This <a href="https://www.sciencedirect.com/science/article/pii/S0016718515000834">has not always been forthcoming</a>, particularly when flood management is considered unduly expensive or environmentally damaging. </p>
<p>For example, river dredging was long considered an <a href="https://www.tandfonline.com/doi/full/10.1080/09640568.2016.1157458?scroll=top&needAccess=true&role=tab">unsuitable flood mitigation technique</a> for the Somerset Levels in southwest England. But winter flooding in 2013-14 led to its immediate and <a href="https://www.bbc.co.uk/news/uk-england-somerset-29851345">ultimately successful implementation</a>.</p>
<p>In the absence of these changes, the UK should brace for a fresh wave of flooding at the end of winter. Driven by a La Niña event, but exacerbated by urban development in areas prone to flooding and the impacts of climate change, the effects could be severe. </p>
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<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">
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<p><strong><em>Don’t have time to read about climate change as much as you’d like?</em></strong>
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<p class="fine-print"><em><span>Jonathan Paul does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>The Met Office has predicted that England is to be affected by flooding this February.Jonathan Paul, Lecturer (Assistant Professor) in Earth Science, Royal Holloway University of LondonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1966552022-12-19T20:56:35Z2022-12-19T20:56:35Z5,700 years of sea-level change in Micronesia hint at humans arriving much earlier than we thought<figure><img src="https://images.theconversation.com/files/501265/original/file-20221215-13-q12vwv.jpg?ixlib=rb-1.1.0&rect=72%2C114%2C3953%2C2565&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Mangrove forests on Pohnpei are archives of sea-level change.</span> <span class="attribution"><span class="source">Juliet Sefton</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Sea levels in Micronesia rose much faster over the past 5,000 years than previously thought, according to our new study <a href="https://www.pnas.org/cgi/doi/10.1073/pnas.2210863119">published today in Proceedings of the National Academy of Sciences</a>.</p>
<p>This sea-level rise is shown by the accumulation of mangrove sediments on the islands of Pohnpei and Kosrae. The finding may change how we think about when people migrated into Remote Oceania, and where they might have voyaged from.</p>
<h2>Formidable voyagers</h2>
<p>While recent decades saw <a href="https://www.science.org/doi/10.1126/science.abm6536">significant advancements</a> in linguistic, bio-anthropological and archaeological research in the region, the exact pattern and timing of human settlement of Remote Oceania is still debated.</p>
<p>Humans began migration into Remote Oceania – the area of the “open” Pacific Ocean east of New Guinea and the Philippines – some 3,300–3,500 years ago. This migration required formidable long-distance ocean voyaging of the likes never seen before in human history.</p>
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Read more:
<a href="https://theconversation.com/what-wind-currents-and-geography-tell-us-about-how-people-first-settled-oceania-67410">What wind, currents and geography tell us about how people first settled Oceania</a>
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<p>The region of Micronesia extends many thousands of kilometres and contains thousands of low-lying atolls. Many of these atolls formed roughly 2,500 years ago when the sea level in the region <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2011GL049163">stabilised close to where it is today</a>.</p>
<p>Before that, the sea level might have been up to two metres higher than at present. People could only settle these atolls successfully once sea levels had lowered and stabilised.</p>
<p>But there are also older and higher volcanic islands in Micronesia. Across Remote Oceania, these higher islands were more desirable for settlement than low-lying atolls because they have more reliable freshwater sources, more developed soils for agriculture, and are less vulnerable to storm surges.</p>
<p>We looked at the published ages of settlement across the western part of Remote Oceania and found that high islands tend to show earlier ages of settlement compared to atolls, which is what we would expect. But we don’t see this pattern in Micronesia: the high islands of Pohnpei and Kosrae show settlement ages about 1,000 years later than other similar islands. Why?</p>
<h2>Mangrove clues</h2>
<p>Deep within the mangrove forests of Pohnpei and Kosrae, <a href="https://www.scirp.org/journal/paperinformation.aspx?paperid=53298">previous</a> <a href="https://pubs.geoscienceworld.org/gsa/gsabulletin/article-abstract/81/7/1895/6917/Paludal-Stratigraphy-of-Truk-Ponape-and-Kusaie">researchers found</a> mangrove sediments up to five metres deep. The only explanation for such deep mangrove sediments is sustained sea-level rise.</p>
<p>Mangroves live at the coast, between low tide and high tide. Therefore, as sea level rises, organic carbon and sediments accumulate beneath the mangrove forests, <a href="https://theconversation.com/rising-seas-allow-coastal-wetlands-to-store-more-carbon-113020">creating deep soils</a>.</p>
<p>We visited the mangroves on Pohnpei and Kosrae and collected sediment cores to find out how old the sediments beneath them were. Our new data, as well as previous works, show that the oldest mangrove sediment is about 5,700 years old.</p>
<p>From this, we calculated that over the past 5,700 years, sea level rose by about four metres. The most likely cause for this rise is that the islands are sinking: the land is going down relative to the sea surface. </p>
<p>In our new study, we suggest this sea-level rise obscured the archaeological record on Pohnpei and Kosrae. Consequently, evidence of earlier settlement – in line with other high islands – may be submerged today.</p>
<p>It is possible that people settled this region of Micronesia much earlier than previously thought, which also raises questions about whether people voyaged from the west or from the south to reach these islands. </p>
<h2>A testament to rising seas</h2>
<p>The <a href="https://whc.unesco.org/en/list/1503/">UNESCO World Heritage Site of Nan Madol</a> on Pohnpei may also stand as a testament to rising seas. Nan Madol is an impressive array of abandoned megalithic buildings constructed from dark basalt columns and crushed coral.</p>
<p>This site has been dubbed the “<a href="https://www.cambridge.org/core/journals/quaternary-research/article/earliest-direct-evidence-of-monument-building-at-the-archaeological-site-of-nan-madol-pohnpei-micronesia-identified-using-230thu-coral-dating-and-geochemical-sourcing-of-megalithic-architectural-stone/0338E86D312973BA0B32D56A5D297FAF">Venice of the Pacific</a>” because of the characteristic network of waterways around the buildings, resembling canals and islets.</p>
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<a href="https://images.theconversation.com/files/501432/original/file-20221215-20-9gcc7c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Aerial view of stone constructions topped with lush jungle greenery, with brown canal-like waterways around them" src="https://images.theconversation.com/files/501432/original/file-20221215-20-9gcc7c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/501432/original/file-20221215-20-9gcc7c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/501432/original/file-20221215-20-9gcc7c.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/501432/original/file-20221215-20-9gcc7c.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/501432/original/file-20221215-20-9gcc7c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/501432/original/file-20221215-20-9gcc7c.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/501432/original/file-20221215-20-9gcc7c.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">Nan Madol is characterised by waterways snaking around ancient megalithic buildings.</span>
<span class="attribution"><span class="source">KKvintage/Shutterstock</span></span>
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<p>Our record of sea-level rise from the mangrove sediment shows that <a href="https://www.cambridge.org/core/journals/quaternary-research/article/earliest-direct-evidence-of-monument-building-at-the-archaeological-site-of-nan-madol-pohnpei-micronesia-identified-using-230thu-coral-dating-and-geochemical-sourcing-of-megalithic-architectural-stone/0338E86D312973BA0B32D56A5D297FAF">when Nan Madol was constructed</a> (around 1180 to 1200 CE), the sea level was nearly one metre lower than it is today.</p>
<p>We suggest that it is unlikely Nan Madol was built with canals and islands in mind. Rather, the canals and islets are a result of sea-level rise over nearly 1,000 years.</p>
<p>Much like island nations today, large stone walls may have been constructed to protect the site from waves that were slowly encroaching higher and higher. </p>
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Read more:
<a href="https://theconversation.com/islands-lost-to-the-waves-how-rising-seas-washed-away-part-of-micronesias-19th-century-history-82981">Islands lost to the waves: how rising seas washed away part of Micronesia's 19th-century history</a>
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<p class="fine-print"><em><span>Juliet Sefton received funding from the US National Science Foundation (award number OCE-1831382) and was hosted by Tufts University while conducting this research. Juliet now works at Monash University. </span></em></p><p class="fine-print"><em><span>Andrew Kemp receives funding from the US National Science Foundation (award OCE-1831382). </span></em></p><p class="fine-print"><em><span>Mark D. McCoy has received funding from the US National Science Foundation, New Zealand's Marsden Fund, and National Geographic.</span></em></p>A new analysis of deep soil sediments accumulated in the mangroves of Pohnpei and Kosrae islands reveals a potentially different history of human arrival in this oceanic region.Juliet Sefton, Assistant Lecturer, Monash UniversityAndrew Kemp, Associate professor, Tufts UniversityMark D. McCoy, Associate professor, Southern Methodist UniversityLicensed as Creative Commons – attribution, no derivatives.