tag:theconversation.com,2011:/ca/topics/climate-science-5941/articlesClimate science – The Conversation2024-03-20T19:04:04Ztag:theconversation.com,2011:article/2261222024-03-20T19:04:04Z2024-03-20T19:04:04Z‘How long before climate change will destroy the Earth?’: research reveals what Australian kids want to know about our warming world<figure><img src="https://images.theconversation.com/files/582994/original/file-20240320-16-lx7lnj.jpg?ixlib=rb-1.1.0&rect=0%2C19%2C6374%2C4224&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/young-boy-taking-photos-land-burnt-1563856276">Shutterstock</a></span></figcaption></figure><p>Every day, more children discover they are living in a climate crisis. This makes <a href="https://www.thelancet.com/journals/lanplh/article/PIIS2542-5196(21)00278-3/fulltext">many children feel</a> sad, anxious, angry, powerless, confused and frightened about what the future holds. </p>
<p>The climate change burden facing young people is inherently unfair. But they have the potential to be the most powerful generation when it comes to creating change.</p>
<p>Research and public debate so far has largely <a href="https://www.hhrjournal.org/2014/07/climate-change-childrens-rights-and-the-pursuit-of-intergenerational-climate-justice/">failed to engage</a> with the voices and opinions of children – instead, focusing on the views of adults.
<a href="https://www.cell.com/one-earth/fulltext/S2590-3322(24)00100-3">Our research</a> set out to change this. </p>
<p>We asked 1,500 children to tell us what they wanted to know about climate change. The results show climate action, rather than the scientific cause of the problem, is their greatest concern. It suggests climate change education in schools must become more holistic and empowering, and children should be given more opportunities to shape the future they will inherit.</p>
<h2>Questions of ‘remarkable depth’</h2>
<p>In Australia, research shows <a href="https://www.researchgate.net/publication/264546580_Children's_Fears_hopes_and_heroes_Modern_childhood_in_Australia">43% of children</a> aged 10 to 14 are worried about the future impact of climate change, and one in four believe the world will end before they grow up.</p>
<p>Children are often <a href="https://doi.org/10.1002/wcc.853">seen as</a> passive, marginal actors in the climate crisis. Evidence of an intergenerational divide is also emerging. Young people report feeling <a href="https://www.sciencedirect.com/science/article/pii/S0959378023001103">unheard</a> and <a href="https://www.sciencedirect.com/science/article/abs/pii/S0016718520302748?via%3Dihub">betrayed by older generations</a> when it comes to climate change. </p>
<p>Our study examined 464 questions about climate change submitted to the <a href="https://curiousclimate.org.au/schools/">Curious Climate Schools</a> program in Tasmania in 2021 and 2022. The questions were asked by primary and high school students aged 7 to 18.</p>
<p>The children’s questions reveal a remarkable depth of consideration about climate change.</p>
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Read more:
<a href="https://theconversation.com/how-well-does-the-new-australian-curriculum-prepare-young-people-for-climate-change-183356">How well does the new Australian Curriculum prepare young people for climate change?</a>
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<img alt="teenagers hold signs at rally" src="https://images.theconversation.com/files/582991/original/file-20240320-30-u8t2vi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/582991/original/file-20240320-30-u8t2vi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/582991/original/file-20240320-30-u8t2vi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/582991/original/file-20240320-30-u8t2vi.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/582991/original/file-20240320-30-u8t2vi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/582991/original/file-20240320-30-u8t2vi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/582991/original/file-20240320-30-u8t2vi.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">
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<span class="caption">The vast majority of children worry about climate change.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/london-uk-united-kingdom-15th-february-1315212515">Shutterstock</a></span>
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<h2>Kids are thinking globally</h2>
<p>The impacts of climate change were discussed in 38% of questions. About 10% of questions asked about impacts on places, such as:</p>
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<p>With the rate of climate change, what will the Earth be like when I’m an adult?</p>
<p>What does the melting of glaciers in Antarctica mean for Tassie (Tasmania) and our climate?</p>
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<p>These questions demonstrate children’s understanding of the global scale of the climate crisis and their concern about places close to home.</p>
<p>How climate change will affect humans accounted for 12% of questions. Impacts on animals and biodiversity were the subject of 9% of questions. Examples include:</p>
<blockquote>
<p>Will climate change make us live elsewhere, eg underwater or in space?</p>
<p>What species may become extinct due to climate change, which species could adapt to changing conditions and have we already seen this begin to happen?</p>
</blockquote>
<p>Approximately 7% of questions asked about ice melting and/or sea-level rise, while 3% asked about extreme weather or disasters.</p>
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<img alt="four children in school uniforms reading book" src="https://images.theconversation.com/files/582988/original/file-20240320-30-1bimcz.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C6262%2C4694&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/582988/original/file-20240320-30-1bimcz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/582988/original/file-20240320-30-1bimcz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/582988/original/file-20240320-30-1bimcz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/582988/original/file-20240320-30-1bimcz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/582988/original/file-20240320-30-1bimcz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/582988/original/file-20240320-30-1bimcz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Children wonder what Earth will look like when they are adults.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/row-multiethnic-elementary-students-reading-book-143878204">Shutterstock</a></span>
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<h2>‘What can we do?’</h2>
<p>Action on climate change was the most frequent theme, discussed in 40% of questions. Some questions involved the kinds of action needed and others focused on the challenges in taking action. They include:</p>
<blockquote>
<p>How would you make rapid climate improvements without sacrificing industry and finance?</p>
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<p>Around 16% of questions asked about, or implied, who was responsible for climate action. Governments and politicians were the largest group singled out. Other questions asked about the responsibilities of schools, communities, states, countries and individuals. Examples include:</p>
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<p>What can I do as a 12-year-old to help the planet, and why will these actions help us?</p>
<p>If the world knows about climate change, why has not much happened?</p>
</blockquote>
<p>Some 20% of questions suggested action by specific sectors of the economy. This included stopping using fossil fuels and moving to renewable energy or nuclear power. Some suggested action related to food, agriculture or fisheries.</p>
<h2>Existential worries</h2>
<p>In 27% of questions, students raised existential concerns about climate change. This reveals the urgency and frustration many children feel.</p>
<p>The largest group of these questions (15%) asked for predictions of future events. Some 5% of questions implied the planet, or humanity, was doomed. They included:</p>
<blockquote>
<p>Will all the reefs die?</p>
<p>How long before climate change will destroy the Earth?</p>
<p>How long will we be able to survive on our planet if we do nothing to try to slow down/reverse climate change?</p>
</blockquote>
<h2>Why is Earth getting hot?</h2>
<p>Scientific questions about climate change made up 25% of the total. The largest group related to the causes and physical processes, such as: </p>
<blockquote>
<p>What causes the Earth to get hotter due to climate change?</p>
<p>Would our world be the same now if the Industrial Revolution hadn’t happened?</p>
<p>How do they know the climate and percentage of gases, such as methane, in the 1800s?</p>
</blockquote>
<h2>What all this means</h2>
<p>Our analysis indicates children are very concerned about how climate change affects the things and places they care about. Children also want to know how to contribute to solutions – either through their own actions or influencing adults, industries and governments. Children asked fewer questions about the scientific evidence for climate change. </p>
<p>So what are the implications of this?</p>
<p>Research shows that where climate change is taught in schools, it is primarily <a href="http://www.jsedimensions.org/wordpress/wp-content/uploads/2015/11/Siperstein-JSE-Nov-2015-Hope-Issue-PDF.pdf">represented as</a> a scientific and environmental issue, without focus on the social and political causes and challenges.</p>
<p>While children need information about the science of global warming, our research suggests this is not enough. Climate change should be integrated into all subjects in the curriculum, from social studies to maths to food. </p>
<p>Teachers should also be trained to understand climate challenges themselves, and to identify and support students suffering from climate distress.</p>
<p>And children must be given opportunities to get involved in shaping the future. Governments and industry should commit to listening to children’s concerns about climate change, and acting on them.</p>
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Read more:
<a href="https://theconversation.com/i-tend-to-be-very-gentle-how-teachers-are-navigating-climate-change-in-the-classroom-212370">'I tend to be very gentle': how teachers are navigating climate change in the classroom</a>
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<p class="fine-print"><em><span>Chloe Lucas received funding from the Centre for Marine Socioecology, the University of Tasmania, and the Tasmanian Climate Change Office for the research and engagement reported in this article, as part of the Curious Climate Schools program. She is also funded by the Australian Research Council. Chloe is a member of the Centre for Marine Socioecology, the Institute of Australian Geographers and the International Environmental Communication Association, and is a member of the Editorial Board of Australian Geographer.</span></em></p><p class="fine-print"><em><span>Charlotte Earl-Jones received funding from the Centre for Marine Socioecology, the University of Tasmania, and the Tasmanian Climate Change Office for the research and engagement reported in this article, as part of the Curious Climate Schools program. She is also funded by Westpac Scholars Trust and the Australian Commonwealth Government Research Training Program. She is a member of the Institute of Australian Geographers. </span></em></p><p class="fine-print"><em><span>Gabi Mocatta received funding from the Centre for Marine Socioecology, the University of Tasmania and the Tasmanian Climate Change Office (now re-named Renewables, Climate and Future Industries Tasmania) for the research and engagement reported here. She is also President of the Board of the International Environmental Communication Association.</span></em></p><p class="fine-print"><em><span>Gretta Pecl receives funding from the Australian Research Council, Department of Agriculture Water and the Environment, Department of Primary Industries NSW, Department of Premier and Cabinet (Tasmania), the Fisheries Research & Development Corporation, and has received travel funding support from the Australian government for participation in the IPCC process. </span></em></p><p class="fine-print"><em><span>Kim Beasy received funding from the Centre for Marine Socioecology, the University of Tasmania, and the Tasmanian Climate Change Office for the research and engagement reported in this article, as part of the Curious Climate School program. She is a member of the Centre of Marine Socioecology and the Australian Association of Environmental Education. </span></em></p><p class="fine-print"><em><span>Rachel Kelly receives funding from the Fisheries Research and Development Corporation, and the Centre for Marine Socioecology at the University of Tasmania.</span></em></p>The result shows climate change education in schools must become more holistic and empowering, and children should be allowed to shape the future they will inherit.Chloe Lucas, Lecturer and Research Fellow, School of Geography, Planning, and Spatial Sciences. Coordinator, Education for Sustainability Tasmania, University of TasmaniaCharlotte Earl-Jones, PhD Candidate, University of TasmaniaGabi Mocatta, Research Fellow in Climate Change Communication, Climate Futures Program, University of Tasmania, and Lecturer in Communication, Deakin UniversityGretta Pecl, Professor, at IMAS and Director of the Centre for Marine Socioecology, University of TasmaniaKim Beasy, Senior Lecturer in Curriculum and Pedagogy, University of TasmaniaRachel Kelly, Postdoctoral Research Fellow, Future Ocean and Coastal Infrastructures (FOCI) Consortium, Memorial University, Canada, and Centre for Marine Socioecology, University of TasmaniaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2251452024-03-08T13:35:18Z2024-03-08T13:35:18ZDune: what the climate of Arrakis can tell us about the hunt for habitable exoplanets<p>Frank Herbert’s Dune is epic sci-fi storytelling with an environmental message at its heart. The novels and movies are set on the desert planet of Arrakis, which various characters dream of transforming into a greener world – much like some envision for Mars today. </p>
<p>We investigated Arrakis using a <a href="https://theconversation.com/dune-we-simulated-the-desert-planet-of-arrakis-to-see-if-humans-could-survive-there-170181">climate model</a>, a computer program similar to those used to give weather forecasts. We found the world that Herbert had created, well before climate models even existed, was remarkably accurate – and would be habitable, if not hospitable.</p>
<p>However, Arrakis wasn’t always a desert. In Dune lore, 91% of the planet was once covered by oceans, until some ancient catastrophe led to its desertification. What water remained was further removed by sand trout, an invasive species brought to Arrakis. These proliferated and carried liquid into cavities deep underground, leading to the planet becoming more and more arid.</p>
<p>To see what a large ocean would mean for the planet’s climate and habitability, we have now used the same climate model – putting in an ocean while changing no other factors. </p>
<p>When most of Arrakis is flooded, we calculate that the global average temperature would be reduced by 4°C. This is mostly because oceans add moisture to the atmosphere, which leads to more snow and certain types of cloud, both of which reflect the sun’s energy back into space. But it’s also because oceans on Earth and (we assume) on Arrakis emit “halogens” that <a href="https://www.nature.com/articles/s41586-023-06119-z">cool the planet</a> by depleting ozone, a potent greenhouse gas which Arrakis would have significantly more of than Earth.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/580451/original/file-20240307-18-5829gu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Map of Arrakis" src="https://images.theconversation.com/files/580451/original/file-20240307-18-5829gu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/580451/original/file-20240307-18-5829gu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=207&fit=crop&dpr=1 600w, https://images.theconversation.com/files/580451/original/file-20240307-18-5829gu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=207&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/580451/original/file-20240307-18-5829gu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=207&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/580451/original/file-20240307-18-5829gu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=261&fit=crop&dpr=1 754w, https://images.theconversation.com/files/580451/original/file-20240307-18-5829gu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=261&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/580451/original/file-20240307-18-5829gu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=261&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 authors gathered information from the books and the Dune Encyclopedia to build their original model. Then they added an ocean with 1,000 metres average depth.</span>
<span class="attribution"><span class="source">Farnsworth et al</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Unsurprisingly, the ocean world is a whopping 86 times wetter, as so much water evaporates from the oceans. This means plants can grow as water is no longer a finite resource, as it is on desert Arrakis.</p>
<h2>A wetter world would be more stable</h2>
<p>Oceans also reduce temperature extremes, as water heats and cools more slowly than land. (This is one reason Britain, surrounded by oceans, has relatively mild winters and summers, while places far inland tend to be <a href="https://weatherspy.net/?city=London&city=Winnipeg&metric=1">hotter in summer and very cold in winter</a>). The climate of an ocean planet is therefore more stable than a desert world. </p>
<p>In desert Arrakis, temperatures would reach 70°C or more, while in its ocean state, we put the highest recorded temperatures at about 45°C. That means the ocean Arrakis would be liveable even in summer. Forests and arable crops could grow outside of the (still cold and snowy) poles. </p>
<p>There is one downside, however. Tropical regions would be buffeted by large cyclones since the huge, warm oceans would contain lots of the energy and moisture required to drive hurricanes.</p>
<h2>The search for habitable planets</h2>
<p>All this isn’t an entirely abstract exercise, as scientists searching for habitable “exoplanets” in distant galaxies are looking for these sorts of things too. At the moment, we can only detect such planets using huge telescopes in space to search for those that are similar to Earth in size, temperature, available energy, ability to host water, and other factors. </p>
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<figcaption>
<span class="caption">Both desert and ocean Arrakis are considerably more habitable than any other planet we have discovered.</span>
<span class="attribution"><span class="source">Farnsworth et al</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
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<p>We know that desert worlds are probably more common than Earth-like planets in the universe. Planets with potentially life-sustaining oceans will usually be found in the so-called “Goldilocks zone”: far enough from the Sun to avoid being too hot (so further away than boiling hot Venus), but close enough to avoid everything being frozen (so nearer than Jupiter’s icy moon Ganymede). </p>
<p>Research has found this habitable zone is particularly <a href="https://www.liebertpub.com/doi/10.1089/ast.2010.0545">small for planets with large oceans</a>. Their water is at risk of either completely freezing, therefore making the planet even colder, or of evaporating as part of a runaway greenhouse effect in which a layer of water vapour prevents heat from escaping and the planet gets hotter and hotter. </p>
<p>The habitable zone is therefore much larger for desert planets, since at the outer edge they will have less snow and ice cover and will absorb more of their sun’s heat, while at the inner edge there is less water vapour and so less risk of a runaway greenhouse effect.</p>
<p>It’s also important to note that, though distance from their local star can give a general average temperature for a planet, such an average can be misleading. For instance, both desert and ocean Arrakis have a habitable average temperature, but the day-to-day temperature extremes on the ocean planet are much more hospitable. </p>
<p>Currently, even the most powerful telescopes cannot sense temperatures at this detail. They also cannot see in detail how the continents are arranged on distant planets. This again could mean the averages are misleading. For instance, while the ocean Arrakis we modelled would be very habitable, most of the land is in the polar regions which are under snow year-round – so the actual amount of inhabitable land is much less. </p>
<p>Such considerations could be important in our own far-future, when the Earth is projected to form a <a href="https://www.nature.com/articles/s41561-023-01259-3">supercontinent centred on the equator</a>. That continent would make the planet far too hot for mammals and other life to survive, potentially leading to mass extinction.</p>
<p>If the most likely liveable planets in the universe are deserts, they may well be very extreme environments that require significant technological solutions and resources to enable life – desert worlds will probably not have an oxygen-rich atmosphere, for instance.</p>
<p>But that won’t stop humans from trying. For instance, Elon Musk and SpaceX have grand ambitions to <a href="https://www.nytimes.com/2023/10/05/science/elon-musk-spacex-starship-mars.html">create a colony</a> on our closest desert world, Mars. But the many challenges they will face only emphasises how important our own Earth is as the cradle of civilisation – especially as ocean-rich worlds may not be as plentiful as we’d hope. If humans eventually colonise other worlds, they’re likely to have to deal with many of the same problems as the characters in Dune.</p>
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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>Alex Farnsworth works for the University of Bristol and receives funding from NERC and the Chinese Academy of Sciences.</span></em></p><p class="fine-print"><em><span>Sebastian Steinig works for the University of Bristol and receives funding from NERC.</span></em></p><p class="fine-print"><em><span>Michael Farnsworth does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Climate scientists have simulated Arrakis as a desert and with its long-lost oceans.Alex Farnsworth, Senior Research Associate in Meteorology, University of BristolMichael Farnsworth, Research Lead Future Electrical Machines Manufacturing Hub, University of SheffieldSebastian Steinig, Research Associate in Paleoclimate Modelling, University of BristolLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2237682024-02-20T16:52:21Z2024-02-20T16:52:21ZA single Antarctic heatwave or storm can noticeably raise the sea level<p>A heat wave in Greenland and a storm in Antarctica. These kinds of individual weather “events” are increasingly being supercharged by a warming climate. But despite being short-term events they can also have a much longer-term effect on the world’s largest ice sheets, and may even lead to tipping points being crossed in the polar regions.</p>
<p>We have <a href="https://www.nature.com/articles/s43017-023-00509-7.epdf?sharing_token=EJZ02zq3kFQO4XKwZVTBLdRgN0jAjWel9jnR3ZoTv0NlXBkse_V2fGVmyGVwGFcXe8LM4zjSaytnzbxkpU3vleMHbbCbjypxjcJ3p1wJddVoe1nKU4klsbQfMwCvE-m9plem7c8GygdxBfIr9KNkFEXV23v6oF28LZQkvsWpQm4%3D">just published</a> research looking at these sudden changes in the ice sheets and how they may impact what we know about sea level rise. One reason this is so important is that the global sea level is predicted to rise by anywhere between 28 cm and 100cm by the year 2100, according to <a href="https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_Chapter09.pdf">the IPCC</a>. This is a huge range – 70 cm extra sea-level rise would affect many millions more people. </p>
<p>Partly this uncertainty is because we simply don’t know whether we’ll curb our emissions or continue with business as usual. But while possible social and economic changes are at least <a href="https://www.carbonbrief.org/explainer-how-shared-socioeconomic-pathways-explore-future-climate-change/">factored in</a> to the above numbers, the IPCC acknowledges its estimate does not take into account deeply uncertain ice-sheet processes. </p>
<h2>Sudden accelerations</h2>
<p>The sea is rising for two main reasons. First, the water itself is very slightly expanding as it warms, with this process responsible for <a href="https://theconversation.com/how-much-will-our-oceans-warm-and-cause-sea-levels-to-rise-this-century-weve-just-improved-our-estimate-166417">about a third</a> of the total expected sea-level rise. </p>
<p>Second, the world’s largest ice sheets in Antarctica and Greenland are melting or sliding into the sea. As the ice sheets and glaciers respond relatively slowly, the sea will also continue to rise for centuries.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/576797/original/file-20240220-30-8eophf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Large glacier in mountains meeting the ocean" src="https://images.theconversation.com/files/576797/original/file-20240220-30-8eophf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/576797/original/file-20240220-30-8eophf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/576797/original/file-20240220-30-8eophf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/576797/original/file-20240220-30-8eophf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/576797/original/file-20240220-30-8eophf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/576797/original/file-20240220-30-8eophf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/576797/original/file-20240220-30-8eophf.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">Elephant Foot Glacier in northern Greenland.</span>
<span class="attribution"><span class="source">Nicolaj Larsen / shutterstock</span></span>
</figcaption>
</figure>
<p>Scientists have long known that there is a potential for sudden accelerations in the rate at which ice is lost from Greenland and Antarctica which could cause considerably more sea-level rise: perhaps a metre or more in a century. Once started, this would be impossible to stop. </p>
<p>Although there is a lot of uncertainty over how likely this is, there is some evidence that it happened <a href="https://www.nature.com/articles/nature17145">about 130,000 years ago</a>, the last time global temperatures were anything close to the present day. We cannot discount the risk. </p>
<p>To improve predictions of rises in sea level we therefore need a clearer understanding of the Antarctic and Greenland ice sheets. In particular, we need to review if there are weather or climate changes that we can already identify that might lead to abrupt increases in the speed of mass loss.</p>
<h2>Weather can have long-term effects</h2>
<p><a href="https://www.nature.com/articles/s43017-023-00509-7.epdf?sharing_token=EJZ02zq3kFQO4XKwZVTBLdRgN0jAjWel9jnR3ZoTv0NlXBkse_V2fGVmyGVwGFcXe8LM4zjSaytnzbxkpU3vleMHbbCbjypxjcJ3p1wJddVoe1nKU4klsbQfMwCvE-m9plem7c8GygdxBfIr9KNkFEXV23v6oF28LZQkvsWpQm4%3D">Our new study</a>, involving an international team of 29 ice-sheet experts and published in the journal Nature Reviews Earth & Environment, reviews evidence gained from observational data, geological records, and computer model simulations. </p>
<p>We found several examples from the past few decades where weather “events” – a single storm, a heatwave – have led to important long-term changes. </p>
<p>The ice sheets are built from millennia of snowfall that gradually compresses and starts to flow towards the ocean. The ice sheets, like any glacier, respond to changes in the atmosphere and the ocean when the ice is in contact with sea water. </p>
<p>These changes could take place over a matter of hours or days or they may be long-term changes from months to years or thousands of years. And processes may interact with each other on different timescales, so that a glacier may gradually thin and weaken but remain stable until an abrupt short-term event pushes it over the edge and it rapidly collapses. </p>
<p>Because of these different timescales, we need to coordinate collecting and using more diverse types of data and knowledge.</p>
<p>Historically, we thought of ice sheets as slow-moving and delayed in their response to climate change. In contrast, our research found that these huge glacial ice masses respond in far quicker and more unexpected ways as the climate warms, similarly to the frequency and intensity of hurricanes and heatwaves responding to changes with the climate. </p>
<p>Ground and satellite observations show that sudden heatwaves and large storms can have long-lasting effects on ice sheets. For example a heatwave in July 2023 meant at one point <a href="https://www.carbonbrief.org/guest-post-how-the-greenland-ice-sheet-fared-in-2023/">67% of the Greenland ice sheet surface</a> was melting, compared with around 20% for average July conditions. In 2022 unusually warm rain fell on the <a href="https://www.whoi.edu/oceanus/feature/a-cold-case-filed-conger-ice-shelf-collapse/">Conger ice shelf</a> in Antarctica, causing it to disappear almost overnight.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1679391326326980608"}"></div></p>
<p>These weather-driven events have long “tails”. Ice sheets don’t follow a simple uniform response to climate warming when they melt or slide into the sea. Instead their changes are punctuated by short-term extremes. </p>
<p>For example, brief periods of melting in Greenland can melt far more ice and snow than is replaced the following winter. Or the catastrophic break-up of ice shelves along the Antarctic coast can rapidly unplug much larger amounts of ice from further inland. </p>
<p>Failing to adequately account for this short-term variability might mean we underestimate how much ice will be lost in future.</p>
<h2>What happens next</h2>
<p>Scientists must prioritise research on ice-sheet variability. This means better ice-sheet and ocean monitoring systems that can capture the effects of short but extreme weather events. </p>
<p>This will come from new satellites as well as field data. We’ll also need better computer models of how ice sheets will respond to climate change. Fortunately there are already some promising global <a href="http://imbie.org/">collaborative</a> <a href="https://climate-cryosphere.org/about-ismip6/">initiatives</a>.</p>
<p>We don’t know exactly how much the global sea level is going to rise some decades in advance, but understanding more about the ice sheets will help to refine our predictions.</p>
<hr>
<figure class="align-right ">
<img alt="Imagine weekly climate newsletter" src="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
</figcaption>
</figure>
<p><strong><em>Don’t have time to read about climate change as much as you’d like?</em></strong>
<br><em><a href="https://theconversation.com/uk/newsletters/imagine-57?utm_source=TCUK&utm_medium=linkback&utm_campaign=Imagine&utm_content=DontHaveTimeTop">Get a weekly roundup in your inbox instead.</a> Every Wednesday, The Conversation’s environment editor writes Imagine, a short email that goes a little deeper into just one climate issue. <a href="https://theconversation.com/uk/newsletters/imagine-57?utm_source=TCUK&utm_medium=linkback&utm_campaign=Imagine&utm_content=DontHaveTimeBottom">Join the 30,000+ readers who’ve subscribed so far.</a></em></p>
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<p class="fine-print"><em><span>Edward Hanna receives funding from the UK's Natural Environment Research Council.
The research was sponsored by the World Climate Research Programme’s Climate and Cryosphere project, the International Arctic Science Committee, and the Scientific Committee on Antarctic Research, and resulted from a collaboration following an Ice Sheet Mass Balance and Sea Level expert group workshop.</span></em></p><p class="fine-print"><em><span>Ruth Mottram received funding for this work from the European Union, Horizon Europe Funding Programme for research and innovation under grant agreement Nr. 101060452 and from the Novo Nordisk Foundation for the Challenge project PRECISE (Predicting Ice Sheets on Earth), grant NNF23OC0081251.
</span></em></p>To narrow our predictions of global sea level rise, we need to know more about these sudden ‘non-linear’ changes to ice sheets.Edward Hanna, Professor of Climate Science and Meteorology, University of LincolnRuth Mottram, Climate Scientist, National Centre for Climate Research, Danish Meteorological InstituteLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2160542023-12-08T16:37:45Z2023-12-08T16:37:45ZFrozen methane under the seabed is thawing as oceans warm – and things are worse than we thought<figure><img src="https://images.theconversation.com/files/564513/original/file-20231208-19-zu7c7a.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C5325%2C3547&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/air-bubbles-underwater-background-diving-sea-2317314399">Kichigin / shutterstock</a></span></figcaption></figure><p>Buried beneath the oceans surrounding continents is a naturally occurring frozen form of methane and water. Sometimes dubbed “fire-ice” as you can literally set light to it, marine methane hydrate can melt as the climate warms, uncontrollably releasing methane – a potent greenhouse gas – into the ocean and possibly the atmosphere. </p>
<p>Colleagues and I have just published <a href="https://rdcu.be/dsTTt">research</a> showing more of this methane hydrate is vulnerable to warming than previously thought. This is a worry as that hydrate contains about as much carbon as all of the remaining oil and gas on Earth. </p>
<p>Releasing it from the seabed could cause the oceans to become more acidic and the climate to warm further. This is a dangerous set of circumstances. </p>
<p>The massive venting of methane from similar ancient marine hydrate reservoirs has been linked to some of the severest and most rapid climate changes in the Earth’s history. There is even evidence that the process has started again near the <a href="https://www.nature.com/articles/nature11528">east coast of the US</a>. </p>
<p>I have worked on hydrates for over a decade, mainly looking at the methane hydrate offshore of Mauritania, West Africa. Recently I have taken 3D seismic data intended to reveal oil and gas and repurposed it to map out the hydrates under the ocean floor. Ultimately, I wanted to work out if climate change is causing methane to bubble to the surface. </p>
<p>3D seismic is the geologist’s equivalent of the doctor’s CT scan. It can cover hundreds of square kilometres, and can reveal hydrates a few kilometres below the seabed. Hydrate is easily identified in these giant surveys because the sound waves created by a source of seismic energy towed by a ship reflect off the bottom of the hydrate layers. </p>
<h2>Looking for methane using 3D seismic imagery</h2>
<p>As I settled into a new way of life during the first COVID lockdown in early 2020, I reopened the much-studied dataset and started mapping again. I knew there were many examples of hydrate that had thawed as a result of warming since the last glacial period peaked some 20,000 years ago, and I knew we could detect this on the 3D datasets. </p>
<p>But what was the fate of the methane? Did it reach the oceans and atmosphere? Because if it did, this is a major clue that it could happen again.</p>
<p>Around continents, where the oceans are relatively shallow, hydrate is only just cold enough to remain frozen. So it is very vulnerable to any warming, and that is why these areas have been the focus of most scientific investigations. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/564518/original/file-20231208-19-eq32kq.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="World map with shaded areas near the coasts" src="https://images.theconversation.com/files/564518/original/file-20231208-19-eq32kq.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/564518/original/file-20231208-19-eq32kq.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=357&fit=crop&dpr=1 600w, https://images.theconversation.com/files/564518/original/file-20231208-19-eq32kq.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=357&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/564518/original/file-20231208-19-eq32kq.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=357&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/564518/original/file-20231208-19-eq32kq.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=449&fit=crop&dpr=1 754w, https://images.theconversation.com/files/564518/original/file-20231208-19-eq32kq.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=449&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/564518/original/file-20231208-19-eq32kq.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=449&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 known methane hydrates can be found.</span>
<span class="attribution"><a class="source" href="https://www.researchgate.net/figure/Estimated-methane-hydrate-occurrences-in-the-world-This-map-is-taken-from-the-World_fig2_277009736">World Ocean Review (data: Wallmann et al)</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-sa/4.0/">CC BY-NC-SA</a></span>
</figcaption>
</figure>
<p>The good news is that only 3.5% of the world’s hydrate resides in the vulnerable zone, in this precarious state. Most hydrate is instead deemed to be “safe”, buried hundreds of metres below the seabed in deeper waters tens of kilometres further from land.</p>
<p>But frozen methane in the deep ocean may vulnerable after all. In oceans and seas where the water is deeper than around 450 metres to 700 metres are layer upon layer of sediment that contains the hydrate. And some of it is deeply buried and warmed geothermally by the Earth so, despite being hundreds of metres below the seafloor, it is right at the point of instability. </p>
<p>Some layers of sediment are permeable and create a complex underground plumbing for the gas to move through if it’s liberated during climatic warming. Just like holding a football underwater methane gas wants to push upwards because of its buoyancy and burst through the 100s of metres of sediment layers. </p>
<p>Imposed upon this complex geology has been the seven glacials (or ice ages) and interglacials, which warmed and cooled the system repeatedly over the last million years.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/564031/original/file-20231206-32134-khhda0.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Diagram cross section of sea bed showing rock strata, and map of craters." src="https://images.theconversation.com/files/564031/original/file-20231206-32134-khhda0.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/564031/original/file-20231206-32134-khhda0.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=336&fit=crop&dpr=1 600w, https://images.theconversation.com/files/564031/original/file-20231206-32134-khhda0.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=336&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/564031/original/file-20231206-32134-khhda0.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=336&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/564031/original/file-20231206-32134-khhda0.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=422&fit=crop&dpr=1 754w, https://images.theconversation.com/files/564031/original/file-20231206-32134-khhda0.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=422&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/564031/original/file-20231206-32134-khhda0.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=422&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Example of the sort of seismic images the author used. Left: reflections that represent sedimentary strata and a vertical pipe where methane has pushed upwards and a buried crater that formed as methane vented into the ancient ocean. Right: a map showing other examples of these craters.</span>
<span class="attribution"><span class="source">Richard Davies</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<h2>Methane is migrating</h2>
<p>During this first lockdown of 2020 I found spectacular evidence that during warm periods during the last million or so years methane migrated laterally, upwards and landwards toward Africa and leaked in much shallower water. Beneath a layer of up to 80 metres of sediment are 23 giant craters on the ancient seabed, each one kilometre wide and up to 50 metres deep, big enough to be filled with multiple Wembley stadiums. </p>
<p>The seismic imaging provides the tell tale signs of methane immediately below the craters. And similar craters elsewhere form due to prolonged or explosive release of gas at the seabed. </p>
<p>These craters are not located in the vulnerable zone where all the attention has been – they are landward of it at about 330 metres water depth. With the discovery in hand, I gathered an international team of scientists (modellers, physicists, geoscientists) to work out what caused the formation of these remarkable things and when they formed. Our results are now published in <a href="https://rdcu.be/dsTTt">Nature Geoscience</a>.</p>
<p>We believe they formed as a result of repeated warming periods. These periods impacted hydrate in the deep ocean and the released methane migrated up to 40km towards the continent, to be vented beyond the shallowest hydrate deposits. So during a warming world the volume of hydrate that will be vulnerable to leaking methane is more significant than previously thought. </p>
<p>The positive outlook is that there are many natural barriers to this methane. But be warned, we expect that in some places on earth, as we warm the planet, methane from the deep will escape into our oceans.</p>
<hr>
<figure class="align-right ">
<img alt="Imagine weekly climate newsletter" src="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
</figcaption>
</figure>
<p><strong><em>Don’t have time to read about climate change as much as you’d like?</em></strong>
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<p class="fine-print"><em><span>Funding provided by NERC (NE/W00996X/1)</span></em></p>Undersea ‘fire-ice’ is vulnerable to leaking greenhouse gas, finds new study.Richard Davies, Pro-Vice Chancellor: Global and Sustainability, Newcastle UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2177592023-12-08T16:37:43Z2023-12-08T16:37:43ZThe disagreement between two climate scientists that will decide our future<figure><img src="https://images.theconversation.com/files/564531/original/file-20231208-25-i2uuog.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C2700%2C1797&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/earth-observation-outer-space-elements-this-544968547">Vladi333/Shutterstock</a></span></figcaption></figure><p>Getting to net zero emissions by mid-century is conventionally understood as humanity’s best hope for keeping Earth’s surface temperature (already 1.2°C above its pre-industrial level) from increasing well beyond 1.5°C – potentially reaching a point at which it could cause widespread societal breakdown. </p>
<p>At least one prominent climate scientist, however, disagrees. </p>
<p>James Hansen of Columbia University in the US published <a href="https://academic.oup.com/oocc/article/3/1/kgad008/7335889?searchresult=1">a paper</a> with colleagues in November which claims temperatures are set to rise further and faster than the predictions of the Intergovernmental Panel on Climate Change (IPCC). <a href="https://www.youtube.com/watch?v=NXDWpBlPCY8">In his view</a>, the 1.5°C target is dead. </p>
<p>He also claims net zero is no longer sufficient to prevent warming of more than 2°C. To regain some control over Earth’s rising temperature, Hansen supports accelerating the retirement of fossil fuels, greater cooperation between major polluters that accommodates the needs of the developing world and, controversially, intervening in Earth’s “<a href="https://theconversation.com/why-dimming-the-sun-would-be-an-effective-tool-in-the-fight-against-climate-change-218670">radiation balance</a>” (the difference between incoming and outgoing light and heat) to cool the planet’s surface. </p>
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<p>There would probably be wide support for the first two prescriptions. But Hansen’s support for what amounts to the deliberate reduction of sunlight reaching Earth’s surface has brought into the open an idea that makes many uncomfortable. </p>
<p>Michael Mann from the University of Pennsylvania in the US and another <a href="https://www.scientificamerican.com/article/behind-the-hockey-stick/">titan of climate science</a>, spoke for many when he <a href="https://michaelmann.net/content/comments-new-article-james-hansen">dismissed solar radiation management</a> as “potentially very dangerous” and a “desperate action” motivated by the “fallacy … that large-scale warming will be substantially greater than current-generation models project”. </p>
<p>Their positions are irreconcilable. So who is right – Hansen or Mann?</p>
<h2>Earth’s radiation balance</h2>
<p>First, an explanation. </p>
<p>There are only two ways to reduce global warming. One is to increase the amount of heat radiated from Earth’s surface that escapes to space. The other is to increase the amount of sunlight reflected back to space before it lands on something – whether a particle in the atmosphere or something on Earth’s surface – and is converted to heat.</p>
<p>There are many ways to do both. Anything that reduces the amount of greenhouse gas in the atmosphere will let more heat escape to space (replacing fossil fuels with renewables, eating less meat and tilling the soil less for example). Anything that makes the planet brighter will reflect more sunlight to space (such as refreezing the Arctic, making clouds whiter or putting more reflective particles in the atmosphere). </p>
<p>But the key difference between the two, in terms of their impact on global warming, is their response time. That is, the time it takes for a change in the factors that allow more heat to escape or sunlight to be reflected to appear as a change in Earth’s surface temperature. </p>
<p>Intervening to speed up the loss of heat from Earth’s surface cools the planet slowly, over decades and longer. Intervening to increase the sunlight Earth reflects back to space cools the planet more or less immediately. </p>
<p>The essence of the dispute between Mann and Hansen is whether reducing greenhouse gases, by a combination of reducing new emissions and permanently removing past emissions from the atmosphere, is now enough on its own to prevent warming from reaching levels that threaten economic and social stability.</p>
<p>Mann says it is. Hansen says that, while doing these things remains essential, it is no longer sufficient and we must also make Earth more reflective.</p>
<h2>When will warming end?</h2>
<p>Mann aligns with IPCC orthodoxy when he says that emissions reaching net zero will result, within a decade or two, in Earth’s surface temperature stabilising at the level it has then reached. </p>
<p>In effect, there is no significant warming in the pipeline from past emissions. All future warming will be due to future emissions. This is the basis for the global policy imperative to get to net zero.</p>
<p>In his new paper, Hansen argues that if the atmospheric concentration of greenhouse gases remains close to its current level, the surface temperature will stabilise after several hundred years between 8°C and 10°C above the pre-industrial level.</p>
<p>Of this, at least 2°C will emerge by mid-century, and probably a further 3°C a century from now. A temperature increase of this magnitude would be catastrophic for life on Earth. Hansen adds that to avoid such an outcome, brightening Earth is now necessary to halt the warming in the pipeline from past emissions. </p>
<figure class="align-center ">
<img alt="Crevices in an ice sheet." src="https://images.theconversation.com/files/564511/original/file-20231208-15-2uidqq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/564511/original/file-20231208-15-2uidqq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/564511/original/file-20231208-15-2uidqq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/564511/original/file-20231208-15-2uidqq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/564511/original/file-20231208-15-2uidqq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/564511/original/file-20231208-15-2uidqq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/564511/original/file-20231208-15-2uidqq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Bright surfaces, like ice sheets, reflect light to space.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/deep-crevices-on-ice-sheet-greenland-1641825838">Tobetv/Shutterstock</a></span>
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<p>But at the same time, we must also largely eliminate emissions if we are to stop recreating this problem in the future.</p>
<h2>Still getting hotter…</h2>
<p>We are scientists who study the feasibility and effectiveness of alternative responses to climate change, addressing both the engineering and political realities of enabling change at the scale and speed necessary. </p>
<p>We find Mann’s rebuttal of Hansen’s claims unconvincing. Crucially, Mann does not engage directly with Hansen’s analysis of new data covering the last 65 million years.</p>
<p>Hansen explains how the models used by IPCC scientists to assess future climate scenarios have significantly underestimated the warming effect of increased greenhouse gas emissions, the cooling effect of aerosols and how long the climate takes to respond to these changes. </p>
<p>Besides greenhouse gases, humanity also emits aerosols. These are tiny particles comprising a wide range of chemicals. Some, such as the sulphur dioxide emitted when coal and oil are burned, offset the warming from greenhouse gases by reflecting sunlight back to space. </p>
<p>Others, such as soot, have the opposite effect and add to warming. The cooling aerosols dominate by a large margin.</p>
<p>Hansen projects that in coming months, <a href="https://theconversation.com/air-pollution-cools-climate-more-than-expected-this-makes-cutting-carbon-emissions-more-urgent-192433">lower levels of aerosol pollution</a> from shipping will cause warming of as much as 0.5°C more than IPCC models have predicted. This will take global warming close to 2°C as early as next year, although it is likely then to fall slightly as the present El Niño wanes.</p>
<p>Underpinning Hansen’s argument is his conviction that the climate is more sensitive to greenhouse gases than previously reported. The IPCC estimates that doubling atmospheric CO₂ raises Earth’s temperature by 3°C. Hansen calculates it to be 4.8°C. </p>
<p>This, and the much longer climate response time that Hansen calculates from the historical record, would have a significant impact on climate model projections.</p>
<h2>Time for reflection</h2>
<p>The differences between Mann and Hansen are significant for the global response to climate change. </p>
<p>Mann says that allowing emissions to reach net zero by mid-century is sufficient, while Hansen maintains that on its own it would be disastrous and that steps must now be taken in addition to brighten the planet.</p>
<p>Brightening Earth could also reverse the reductions in reflectivity already caused by climate change. <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2021GL094888">Data indicates</a> that from 1998 to 2017, Earth dimmed by about 0.5 watts per square metre, largely due to the loss of ice.</p>
<p>Given what’s at stake, we hope Mann and Hansen resolve these differences quickly to help the public and policymakers understand what it will take to minimise the likelihood of imminent massive and widespread ecosystem destruction and its disastrous effects on humanity. </p>
<p>While 1.5°C may be dead, there may still be time to prevent cascading system failures. But not if we continue to squabble over the nature and extent of the risks.</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>The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Is reaching net zero emissions by 2050 enough to halt warming? One leading scientist says no.Robert Chris, Honorary Associate, Geography, The Open UniversityHugh Hunt, Professor of Engineering Dynamics and Vibration, University of CambridgeLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2192432023-12-06T16:43:11Z2023-12-06T16:43:11ZClimate tipping points are nearer than you think – our new report warns of catastrophic risk<figure><img src="https://images.theconversation.com/files/563946/original/file-20231206-23-j8coxl.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C3866%2C2585&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/glacier-collapse-perito-moreno-argentina-2127502928">lugazzotti / shutterstock</a></span></figcaption></figure><p>It’s now almost inevitable that 2023 will be the <a href="https://climate.copernicus.eu/copernicus-november-2023-remarkable-year-continues-warmest-boreal-autumn-2023-will-be-warmest-year">warmest year ever recorded by humans</a>, probably the warmest for at least 125,000 years. </p>
<p><a href="https://theconversation.com/what-el-nino-means-for-the-worlds-perilous-climate-tipping-points-209083">Multiple temperature records were smashed</a> with global average temperatures for some periods well above 1.5°C. Antarctic sea ice loss is accelerating at frightening rates along with many other indicators of rapid climate change. Does this mean 2023 is the year parts of the climate tip into a much more dangerous state?</p>
<p>Most people expect that if a system, like someone’s body, an ecosystem, or part of the climate system, becomes stressed, it’ll respond fairly predictably – double the pressure, double the impact, and so on. This holds in many cases, but is not always true. Sometimes a system under stress changes steadily (or “linearly”) up to a point, but beyond that far bigger or abrupt changes can be locked in.</p>
<p>An example of such “nonlinear” changes are “tipping points”, which happen when a system is pushed past a threshold beyond which <a href="https://theconversation.com/climate-tipping-points-could-lock-in-unstoppable-changes-to-the-planet-how-close-are-they-191043">change becomes self-sustaining</a>. This means that even if the original pressure eased off the change would keep on going until the system reaches a sometimes completely different state. </p>
<p>Think of rolling a boulder up a hill. This takes a lot of energy. If that energy input is stopped then the ball will roll back down. But when the top of the hill is reached and the boulder is balanced right at the very top, a tiny push, perhaps even a gust of wind, can be enough to send it rolling down the other side. </p>
<p>The climate system has many potential tipping points, such as ice sheets disappearing or dense rainforests becoming significantly drier and more open. It would be very difficult, effectively impossible, to recover these systems once they go beyond a tipping point. </p>
<p>We along with 200 other scientists from around the world just published the new <a href="https://global-tipping-points.org/">Global Tipping Points Report</a> at the COP28 UN climate talks in Dubai. Our report sets out the science on the “negative” tipping points in the Earth system that could harm both nature and people, as well as the potential “positive” societal tipping points that could accelerate sustainability action. </p>
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Read more:
<a href="https://theconversation.com/climate-tipping-points-can-be-positive-too-our-report-sets-out-how-to-engineer-a-domino-effect-of-rapid-changes-219291">Climate 'tipping points' can be positive too – our report sets out how to engineer a domino effect of rapid changes</a>
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<p>Here we look at the key messages from report sections on <a href="https://global-tipping-points.org/section1/1-earth-system-tipping-points/">tipping points in the Earth system</a>, their <a href="https://global-tipping-points.org/section2/2-tipping-point-impacts/">effects on people</a>, and how to <a href="https://global-tipping-points.org/section3/3-0-governance-of-earth-system-tipping-points/">govern these changes</a>. </p>
<h2>Tipping points in air, land and sea</h2>
<p>Having scoured scientific evidence of past and current changes, and factored in projections from computer models, we have identified over 25 tipping points in the Earth system. </p>
<p>Six of these are in the icebound parts of the planet (the “cryosphere”), including the collapse of massive ice sheets in Greenland and different parts of Antarctica, as well as localised tipping in glaciers and thawing permafrost. Sixteen are in the “biosphere” – the sum of all the world’s ecosystems – including trees dying on a massive scale in <a href="https://climatetippingpoints.info/2021/07/18/amazon-dieback-explainer/">parts of the Amazon</a> and northern boreal forests, degradation of savannas and drylands, nutrient overloading of lakes, coral reef mass mortality, and many mangroves and seagrass meadows dying off. </p>
<p>Finally, we identified four potential tipping points in the circulation of the oceans and atmosphere, including <a href="https://climatetippingpoints.info/2023/08/15/amoc-collapse-explainer/">collapse of deep ocean mixing</a> in the North Atlantic and in the Southern Ocean around Antarctica, and disruption of the West African monsoon. </p>
<p>Human activities are already pushing some of these close to tipping points. The exact thresholds are uncertain, but at today’s global warming of 1.2°C, the widespread loss of warm water coral reefs is already becoming likely, while <a href="https://theconversation.com/climate-tipping-points-could-lock-in-unstoppable-changes-to-the-planet-how-close-are-they-191043">tipping in another four vital climate systems is possible</a>. These are Greenland and West Antarctic ice sheet collapse, North Atlantic circulation collapse, and widespread localised thaw of permafrost. </p>
<p>Beyond 1.5°C several of these become likely, and other systems like mangroves, seagrass meadows, and parts of the boreal forest start to become vulnerable. Some systems can also tip or have their warming thresholds reduced due to other drivers, such as deforestation in the Amazon.</p>
<p>It can be hard to comprehend the consequences of crossing these tipping points. For example, if parts of the Amazon rainforest die, countless species would be lost, and warming would be further amplified as billions of tons of carbon currently locked up in trees and soils makes its way into the atmosphere. Within the region, this could cause trillions of dollars of economic impacts, and expose millions of people to extreme heat. </p>
<p>Given the sheer scale of risks from tipping points, you may assume that economic assessments of climate change include them. Alas, most assessments effectively ignore tipping point risks. This is perhaps the most frightening conclusion of the new report.</p>
<h2>Human societies could tip into something much worse</h2>
<p>There is also the potential for negative tipping in human societies, causing further financial instability, displacement, conflict or polarisation. These would hamper our efforts to limit further Earth system tipping points, and could even bring about a shift to a social system characterised by greater authoritarianism, hostility and alienation that could entirely <a href="https://esd.copernicus.org/articles/14/1171/2023/">derail sustainability transitions</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/563947/original/file-20231206-25-jo6id1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="White coral with fish" src="https://images.theconversation.com/files/563947/original/file-20231206-25-jo6id1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/563947/original/file-20231206-25-jo6id1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/563947/original/file-20231206-25-jo6id1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/563947/original/file-20231206-25-jo6id1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/563947/original/file-20231206-25-jo6id1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/563947/original/file-20231206-25-jo6id1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/563947/original/file-20231206-25-jo6id1.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">When water gets too hot, coral can ‘bleach’ and die.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/coral-bleaching-occurs-when-water-temperatures-570782089">Sabangvideo / shutterstock</a></span>
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<p>A further risk is that most of Earth’s tipping systems interact in ways that destabilise one another. In the worst case, tipping one system makes connected systems more likely to tip too. This could produce a “tipping cascade” like falling dominoes. </p>
<p>The Global Tipping Points Report makes clear that climate change is a key driver for most of these tipping points, and the risk of crossing them can be reduced by urgently cutting greenhouse gas emissions to zero (which “<a href="https://global-tipping-points.org/section4/4-0-positive-tipping-points-in-technology-economy-and-society/">positive tipping points</a>” could accelerate). To help prevent tipping points in the biosphere, we’ll also need to rapidly reduce habitat loss and pollution while supporting ecological restoration and sustainable livelihoods.</p>
<p>Ambitious new governance approaches are needed. Our report recommends international bodies like the UN’s climate talks urgently start taking tipping points into account. Their understanding of dangerous climate change needs a serious update.</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>James Dyke receives funding from the Open Society Foundations. He is an advisor to Faculty for a Future.</span></em></p><p class="fine-print"><em><span>David Armstrong McKay is a Research Impact Fellow at the University of Exeter's Global Systems Institute and an Associated Researcher at Stockholm Resilience Centre. He is currently researching Earth system tipping points as part of the Global Tipping Points Report project (funded by the Bezos Earth Fund) and with the Earth Commission (hosted by non-profit research network Future Earth and is the science component of the Global Commons Alliance, a sponsored project of Rockefeller Philanthropy Advisors, with support from Oak Foundation, MAVA, Porticus, Gordon and Betty Moore Foundation, Herlin Foundation, the Global Environment Facility, and Generation Foundation). He is also a freelance research consultant and science communicator.</span></em></p>Coral reefs are already being lost, and four other vital climate systems may tip soon.James Dyke, Associate Professor in Earth System Science, University of ExeterDavid Armstrong McKay, Researcher in Earth System Resilience, Stockholm UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2169282023-11-02T18:05:50Z2023-11-02T18:05:50ZEl Niño may be drying out the southern hemisphere – here’s how that affects the whole planet<figure><img src="https://images.theconversation.com/files/557296/original/file-20231102-19-vu2x45.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C4493%2C2526&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">FoxPictures / shutterstock</span></span></figcaption></figure><p>It is a well-known fact that water is the key to life on Earth. But it is less well known that only about 1% of all water on the planet is fresh water available to humans, plants or land-based animals.</p>
<p>The rest is in the oceans, or locked up in polar ice sheets and rocks. In a climate changing world, the global distribution of that 1% takes on a whole new significance.</p>
<p>A <a href="https://www.science.org/doi/10.1126/science.adh0716">new study</a> has shown that the southern hemisphere has been drying out more than the northern hemisphere over the past two decades (2001-2020). The authors suggest the principle cause is the weather phenomenon known as <a href="https://theconversation.com/uk/topics/el-nino-5638">El Niño</a>, which occurs every few years when ocean water in the eastern Pacific is warmer than usual.</p>
<p>The findings are based on data from satellites and measurements of river and stream flows, which enabled the authors to model and calculate changes in water availability. Water availability is the net difference between the amount of water supplied to the landscape, in the form of rainfall on land, and the water removed to the atmosphere by general evaporation or by plants through their leaves. </p>
<p>Even though the southern hemisphere has only a quarter of the global land area (excluding Antarctica), it appears to have a substantially greater effect on global water availability than the northern hemisphere. </p>
<p>The new analysis reveals a strong decrease in water availability in South America, most of Africa, and central and northwestern Australia. However, some regions such as the southern part of South America will have more water available.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/557299/original/file-20231102-29-fpmgkz.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Shaded world map" src="https://images.theconversation.com/files/557299/original/file-20231102-29-fpmgkz.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/557299/original/file-20231102-29-fpmgkz.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=350&fit=crop&dpr=1 600w, https://images.theconversation.com/files/557299/original/file-20231102-29-fpmgkz.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=350&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/557299/original/file-20231102-29-fpmgkz.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=350&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/557299/original/file-20231102-29-fpmgkz.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=440&fit=crop&dpr=1 754w, https://images.theconversation.com/files/557299/original/file-20231102-29-fpmgkz.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=440&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/557299/original/file-20231102-29-fpmgkz.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=440&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Trends in water availability 2001-2020. The Southern Hemisphere has more orange than blue.</span>
<span class="attribution"><a class="source" href="https://www.science.org/doi/10.1126/science.adh0716">Zhang et al / Science</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>By contrast, despite significant variations between regions, the study suggests water availability in the northern hemisphere is more or less balanced. This is in part due to extensive human influences such as irrigation, dams and food production. Such factors are more relevant in the northern hemisphere since about 90% of the world population lives there.</p>
<p>But why does any of this rather technical modelling about water availability and drying matter? What are some possible implications if the southern hemisphere is drying out more than the northern?</p>
<h2>What happens in the south affects the north too</h2>
<p>Part of the answer lies in the regions likely to experience increased drying. South America includes the Amazon rainforest, which is a key regulator for the climate, as well as a globally important habitat for species and home to many Indigenous communities. </p>
<p><a href="https://theconversation.com/is-the-amazon-rainforest-on-the-verge-of-collapse-178580">Drying of the rainforest</a> would reduce vegetation and increase the risk of fire. This would be bad news for humans and animals that live in the forest, and has the potential to release <a href="https://theconversation.com/amazon-rainforests-that-were-once-fire-proof-have-become-flammable-91775">billions of tons of carbon</a> currently locked into forest vegetation and soils. </p>
<p>South America is also a major agricultural exporter of soybeans, sugar, meat, coffee and fruits for the global market. Changes in water availability will increase stress on food systems globally.</p>
<p>Drying across most of Africa is also a real challenge. This huge continent has many climatic zones and socio-economic contrasts, with often limited resources to mitigate and adapt. </p>
<p>Pressures on food systems and habitats will create additional stresses across the continent which is already suffering from increases in global food prices linked to inflation and the <a href="https://theconversation.com/how-russia-ukraine-conflict-could-influence-africas-food-supplies-177843">war in Ukraine</a>. </p>
<p>Yields of the staple cassava have been declining due to droughts. And exports such as coffee and cocoa could also be reduced, leading to a spiral of loss of livelihoods, poverty and hunger.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/557300/original/file-20231102-27-fi48yb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Dry landscape, mountains in background" src="https://images.theconversation.com/files/557300/original/file-20231102-27-fi48yb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/557300/original/file-20231102-27-fi48yb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/557300/original/file-20231102-27-fi48yb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/557300/original/file-20231102-27-fi48yb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/557300/original/file-20231102-27-fi48yb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/557300/original/file-20231102-27-fi48yb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/557300/original/file-20231102-27-fi48yb.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">North west Australia is going from dry to very dry.</span>
<span class="attribution"><span class="source">Sara Winter/ shutterstock</span></span>
</figcaption>
</figure>
<p>North-west Australia is one of the country’s great wildernesses. But it would be a major error to consider the region “empty” and therefore unimportant in terms of drying. (Like most environmental issues and concerns, it is rarely advisable to isolate one aspect from another.) </p>
<p>Drying will change vegetation patterns and further increase temperatures, which could be above 35°C for large parts of the year by 2100 if emission rates continue to be high. This would have severe effects on the health of humans and habitats. </p>
<p>Similarly, drying in central Australia has knock-on effects on weather and climate for coastal areas where most of Australia’s major cities and population are situated. Drying trends are also being experienced in the <a href="https://theconversation.com/drying-land-and-heating-seas-why-nature-in-australias-southwest-is-on-the-climate-frontline-170377">south-west</a> and south-east of the country leading to habitat stresses and change, <a href="https://theconversation.com/its-official-australia-is-set-for-a-hot-dry-el-nino-heres-what-that-means-for-our-flammable-continent-209126">wildfires</a>, depleted rivers and impacts on human health, especially in urban areas.</p>
<p>As with many aspects of climate, the exact nature and scale of changes and impacts are hard to predict or model at local or regional scales. But this new paper points to clear shifts in patterns and complex climate processes in the southern hemisphere which will reduce water availability during El Niño events.</p>
<p>Drying will generate additional stresses on habitats and species in key regions. It will also impact human populations with varying capacities to adapt and, ultimately, our global food systems. Although the southern hemisphere is mostly water, what happens there really matters for the whole planet.</p>
<hr>
<figure class="align-right ">
<img alt="Imagine weekly climate newsletter" src="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
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<p><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>Kevin Collins 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>New research finds fresh water losses are concentrated in South America, most of Africa and much of Australia.Kevin Collins, Senior Lecturer, Environment & Systems, The Open UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2159282023-10-18T16:30:09Z2023-10-18T16:30:09ZWhat will happen to the Greenland ice sheet if we miss our global warming targets<figure><img src="https://images.theconversation.com/files/554571/original/file-20231018-17-rfjr6n.JPG?ixlib=rb-1.1.0&rect=19%2C0%2C4372%2C2146&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Bryn Hubbard</span></span></figcaption></figure><p>It’s hard to overstate how crucial Greenland, and its kilometres-thick ice layer, is to climate change. If all that ice melted, the sea would rise by about seven metres – the height of a house. </p>
<p>But what happens if we fail to limit warming to 1.5°C (as looks increasingly likely)? And what happens if we do subsequently manage to rectify that “overshoot” and bring temperatures back down? A team of researchers writing in the journal <a href="https://www.nature.com/articles/s41586-023-06503-9">Nature</a> have now published a study exploring these questions.</p>
<p>In a nutshell, their work shows the worst case scenario of ice sheet collapse and consequent sea-level rise can be avoided – and even partly reversed – if we manage to reduce the global temperatures projected for after 2100. Moreover, the lower and sooner those temperatures fall, the more chance there is of minimising that ice melt and sea-level rise.</p>
<p>We already know that the Greenland ice sheet is losing more than <a href="https://essd.copernicus.org/articles/15/1597/2023/">300 billion cubic metres of ice per year</a>, currently driving global sea levels up by a little less than a millimetre per year. One major worry is that further warming could cross critical thresholds, sometimes referred to as “tipping points”. For example, as the air warms more ice will melt, lowering the elevation of the ice surface and hence exposing it to warmer air temperatures and more melting – even without continued atmospheric warming. </p>
<p>Although far more complex and nuanced in reality, it is feedback processes such as this which dictate that global warming be limited to 1.5°C above pre-industrial levels in order to avoid catastrophes, such as wholescale ice-sheet collapse.</p>
<h2>How to simulate a huge ice sheet in a computer</h2>
<p>It is critically important that we are able to predict how the Greenland ice sheet will respond to future warming. To achieve this, researchers generally use computer models of ice motion. In essence, these divide the ice sheet into tens of thousands of 3D segments and apply physical laws of ice motion to compute how each segment changes over thousands of individual time steps, factoring in things like anticipated climatic change, ice thickness, ice slope and the temperature of the ice interior and ice base.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/554577/original/file-20231018-15-tq49jv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Small tents, huge ice sheet" src="https://images.theconversation.com/files/554577/original/file-20231018-15-tq49jv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/554577/original/file-20231018-15-tq49jv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=277&fit=crop&dpr=1 600w, https://images.theconversation.com/files/554577/original/file-20231018-15-tq49jv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=277&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/554577/original/file-20231018-15-tq49jv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=277&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/554577/original/file-20231018-15-tq49jv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=348&fit=crop&dpr=1 754w, https://images.theconversation.com/files/554577/original/file-20231018-15-tq49jv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=348&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/554577/original/file-20231018-15-tq49jv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=348&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Research field camp on the crevassed surface of the Greenland ice sheet.</span>
<span class="attribution"><span class="source">Bryn Hubbard</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-sa/4.0/">CC BY-NC-SA</a></span>
</figcaption>
</figure>
<p>However, these projections are subject to substantial uncertainties. It’s tough to know exactly how ice moves over bedrock, or what its internal temperature might be. And the climate is made up of many moving parts. Atmospheric and oceanic circulations may also change radically over the thousands or tens of thousands of years it takes for the ice sheet to settle in to a new equilibrium.</p>
<p>In the face of such challenges, a team of researchers led by Nils Bochow of the Arctic University in Norway have published their new study. They ran two independent state-of-the-art computer programs that were able to simulate how the Greenland ice sheet would respond to various possible levels of global warming, over tens of thousands of years. To mimic the effects of overshooting the critical 1.5°C threshold, they include a gradual warming trajectory to a “peak” temperature, followed by a period during which temperature stabilises to a generally lower final “convergence temperature”. </p>
<h2>Good news and bad news</h2>
<p>The results are fascinating. If temperatures peak at 2°C or so, and remain there, then the models – as expected – predict substantial ice sheet collapse after several thousands of years. </p>
<p>However, things change if warming is seriously mitigated post-2100. In those models, inertia in the ice sheet’s response – a bit like the time it takes for a ripple to settle down as it passes across a pond – means that an overshoot is at least partly reversible as long as temperatures are quickly brought back down. </p>
<p>For example, if temperature stabilises by the year 2200 at less than 1.5°C of warming, then the ice sheet should remain smaller than at present, but stable. This is the case irrespective of how far (within reason) peak temperatures overshot 1.5°C in the year 2100. In such cases the sea rise would likely be restricted to a metre or so. </p>
<p>However, such a recovery becomes impossible if it takes too long to get temperatures down or if the convergence temperature remains too high. In those scenarios, ice-sheet collapse and substantial sea-level rise become all but inevitable.</p>
<p>Perhaps the very worst can be avoided then, if we continue to work to reduce global temperatures right through this century and next. Although heartening to some degree, these projections are subject to substantial uncertainty and there is more work to do. In this regard, the authors are at pains to note that their results are not necessarily specific predictions but rather provide insight into possible pathways. </p>
<hr>
<figure class="align-right ">
<img alt="Imagine weekly climate newsletter" src="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
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<p><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>Bryn Hubbard receives funding from the UK's Natural Environment Research Council. He is affiliated with the Centre for Glaciology at Aberystwyth University. </span></em></p>The ice will survive if temperatures are soon brought back down – new study.Bryn Hubbard, Professor of Glaciology, Aberystwyth UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2151402023-10-06T01:53:35Z2023-10-06T01:53:35Z6 reasons why global temperatures are spiking right now<figure><img src="https://images.theconversation.com/files/552428/original/file-20231006-27-7ho178.jpg?ixlib=rb-1.1.0&rect=25%2C10%2C3424%2C2286&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://unsplash.com/photos/6gVvfQEnWtY">Jonas Weckschmied/Unsplash</a></span></figcaption></figure><p>The world is very warm right now. We’re not only seeing record temperatures, but the records are being broken by record-wide margins.</p>
<p>Take the preliminary September global-average temperature anomaly of 1.7°C above pre-industrial levels, for example. It’s an incredible 0.5°C above the previous record.</p>
<p>So why is the world so incredibly hot right now? And what does it mean for keeping our Paris Agreement targets? </p>
<p>Here are six contributing factors – with climate change the main reason temperatures are so high.</p>
<h2>1. El Niño</h2>
<p>One reason for the exceptional heat is we are in a <a href="http://www.bom.gov.au/climate/enso/#tabs=Pacific-Ocean">significant El Niño</a> that is still strengthening. During El Niño we see warming of the surface ocean over much of the tropical Pacific. This warming, and the effects of El Niño in other parts of the world, raises global average temperatures by <a href="https://www.realclimate.org/index.php/archives/2023/01/2022-updates-to-the-temperature-records/">about 0.1 to 0.2°C</a>.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/explainer-el-nino-and-la-nina-27719">Explainer: El Niño and La Niña</a>
</strong>
</em>
</p>
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<p>Taking into account the fact we’ve just come out of a triple La Niña, which cools global average temperatures slightly, and the fact this is the first major El Niño in eight years, it’s not too surprising we’re seeing unusually high temperatures at the moment.</p>
<p>Still, El Niño alone isn’t enough to explain the crazily high temperatures the world is experiencing.</p>
<h2>2. Falling pollution</h2>
<p>Air pollution from human activities cools the planet and has offset some of the warming caused by humanity’s greenhouse gas emissions. There have been efforts to reduce this pollution – since 2020 there has been an <a href="https://sdg.iisd.org/news/imo-advances-measures-to-reduce-emissions-from-international-shipping/">international agreement</a> to reduce sulphur dioxide emissions from the global shipping industry.</p>
<p>It has been speculated this cleaner air has contributed to the recent heat, particularly over the record-warm <a href="https://climate.copernicus.eu/record-breaking-north-atlantic-ocean-temperatures-contribute-extreme-marine-heatwaves">north Atlantic</a> and Pacific regions with high shipping traffic.</p>
<p>It’s likely this is contributing to the extreme high global temperatures – but only on the order of hundredths of a degree. <a href="https://www.carbonbrief.org/analysis-how-low-sulphur-shipping-rules-are-affecting-global-warming/">Recent analysis</a> suggests the effect of the 2020 shipping agreement is about an extra 0.05°C warming by 2050.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/552429/original/file-20231006-15-4t8dca.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A smog shrouded road with motorcycles, trucks and cars barely visible through the pollution" src="https://images.theconversation.com/files/552429/original/file-20231006-15-4t8dca.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/552429/original/file-20231006-15-4t8dca.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/552429/original/file-20231006-15-4t8dca.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/552429/original/file-20231006-15-4t8dca.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/552429/original/file-20231006-15-4t8dca.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/552429/original/file-20231006-15-4t8dca.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/552429/original/file-20231006-15-4t8dca.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">People pass through the rising pollution on the Delhi-Jaipur Expressway in Gurgaon, Haryana, India, on November 12 2021.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/people-pass-through-rising-pollution-on-2073480677">Shutterstock</a></span>
</figcaption>
</figure>
<h2>3. Increasing solar activity</h2>
<p>While falling pollution levels mean more of the Sun’s energy reaches Earth’s surface, the amount of the energy the Sun emits is itself variable. There are different solar cycles, but an 11-year cycle is the most relevant one to today’s climate.</p>
<p>The Sun is becoming <a href="https://edition.cnn.com/2023/07/14/world/solar-maximum-activity-2024-scn/index.html">more active</a> from a minimum in late 2019. This is also contributing a small amount to the spike in global temperatures. Overall, increasing solar activity is contributing only hundredths of a degree at most to the recent global heat. </p>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/this-solar-cycle-the-suns-activity-is-more-powerful-and-surprising-than-predicted-209955">This solar cycle, the sun's activity is more powerful and surprising than predicted</a>
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<h2>4. Water vapour from Hunga Tonga eruption</h2>
<p>On January 15 2022 the underwater <a href="https://www.jpl.nasa.gov/images/pia26006-hunga-tonga-hunga-haapai-eruption">Hunga Tonga–Hunga Haʻapai volcano erupted</a> in the South Pacific Ocean, sending large amounts of water vapour high up into the upper atmosphere. Water vapour is a greenhouse gas, so increasing its concentration in the atmosphere in this way does intensify the greenhouse effect.</p>
<p>Even though the eruption happened almost two years ago, it’s still having a small warming effect on the planet. However, as with the reduced pollution and increasing solar activity, we’re talking about hundredths of a degree.</p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/6oANPi-SWN0?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
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<h2>5. Bad luck</h2>
<p>We see variability in global temperatures from one year to the next even without factors like El Niño or major changes in pollution. Part of the reason this September was so extreme was likely due to weather systems being in the right place to heat the land surface.</p>
<p>When we have persistent high-pressure systems over land regions, as seen recently over places like <a href="https://www.theguardian.com/environment/2023/oct/01/autumn-heat-continues-in-europe-after-record-breaking-september">western Europe</a> and <a href="https://www.abc.net.au/news/2023-09-19/australia-weather-september-heat-records-tumble/102870294">Australia</a>, we see local temperatures rise and the conditions for unseasonable heat.</p>
<p>As water requires more energy to warm and the ocean moves around, we don’t see the same quick response in temperatures over the seas when we have high-pressure systems.</p>
<p>The positioning of weather systems warming up many land areas coupled with persistent ocean heat is likely a contributor to the global-average heat too.</p>
<h2>6. Climate change</h2>
<p>By far the biggest contributor to the overall +1.7°C global temperature anomaly is human-caused climate change. Overall, humanity’s effect on the climate has been a global warming of <a href="https://www.globalwarmingindex.org/">about 1.2°C</a>.</p>
<p>The record-high rate of greenhouse gas emissions means we should expect global warming to accelerate too.</p>
<p>While humanity’s greenhouse gas emissions explain the trend seen in September temperatures over many decades, they don’t really explain the big difference from last September (when the greenhouse effect was almost as strong as it is today) and September 2023.</p>
<p>Much of the difference between this year and last comes back to the switch from La Niña to El Niño, and the right weather systems in the right place at the right time.</p>
<h2>The upshot: we need to accelerate climate action</h2>
<p>September 2023 shows that with a combination of climate change and other factors aligning we can see alarmingly high temperatures.</p>
<p>These anomalies may appear to be above the 1.5°C global warming level referred to in the Paris Agreement, but that’s about keeping <a href="https://climateanalytics.org/briefings/understanding-the-paris-agreements-long-term-temperature-goal/">long-term global warming</a> to low levels and not individual months of heat.</p>
<p>But we are seeing the effects of climate change unfolding more and more clearly.</p>
<p>The most vulnerable are suffering the biggest impacts as wealthier nations continue to emit the largest proportion of greenhouse gases. Humanity must accelerate the path to net zero to prevent more record-shattering global temperatures and damaging extreme events.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/net-zero-by-2050-too-late-australia-must-aim-for-2035-213973">Net zero by 2050? Too late. Australia must aim for 2035</a>
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<img src="https://counter.theconversation.com/content/215140/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Andrew King receives funding from the National Environmental Science Program. </span></em></p>The preliminary global-average temperature anomaly for September is a shocking 1.7°C. These are the drivers of current record-breaking heat.Andrew King, Senior Lecturer in Climate Science, The University of MelbourneLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2062362023-08-21T15:40:48Z2023-08-21T15:40:48ZTo predict future sea level rise, we need accurate maps of the world’s most remote fjords<figure><img src="https://images.theconversation.com/files/543613/original/file-20230821-93007-prjkm7.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C4114%2C1492&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The 10km wide Petermann Fjord in northern Greenland. The author's icebreaker ship is a small dot in the middle. The cliffs on either side are a kilometre high. In the distance is the 'ice tongue' of the glacier flowing into the fjord.</span> <span class="attribution"><span class="source">Martin Jakobsson</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>Understanding how glaciers interact with the ocean is akin to piecing together a colossal jigsaw puzzle. And on various icebreaker expeditions to some of the most remote fjords in northern Greenland, colleagues and I have showed that the shape of the seafloor is one of the key pieces of that puzzle.</p>
<p>To understand why the seabed is so important, we have to look at the glaciers themselves and what is causing them to retreat or even disappear. The large glaciers that meet the ocean in Greenland and Antarctica balance their mass over time largely in pace with the climate. When it snows or rains they accumulate ice, and they lose ice to melting and calving – the process where chunks of ice break off and eventually melt away into the sea. </p>
<p>But over the past few decades they are <a href="https://theconversation.com/greenland-has-lost-3-8-trillion-tonnes-of-ice-since-1992-127752">losing mass at an accelerated pace</a>, with more icebergs calving into the ocean and more ice being melted from below by relatively warm seawater. </p>
<p>Estimating how much mass will be lost is often highlighted as glaciology’s grand challenge as it constitutes a <a href="https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_Chapter09.pdf">large uncertainty</a> in our predictions of future sea-level rise. To hone our predictions, it is crucial to find the areas where warmer ocean water reaches the these glaciers. </p>
<p>Most glaciers in Greenland drain into fjords in which the waters near the surface are very cold, heavily influenced by meltwater from the glaciers. Some fjords also allow in warmer water of Atlantic origin, which is saltier and therefore heavier so it enters the fjords at a greater depth.</p>
<p>The shape and depth (or “bathymetry”) of the seafloor determines whether this warmer water can reach the glaciers and cause them to melt. These fjords may have particularly complex bathymetry as they themselves were formed by glaciers which also eroded the seabed. While the inner parts can be a kilometre deep, a shallower “sill” at the entrance (formed when eroded materials accumulate or from resistant bedrock) can act as a shield against inflowing warmer water.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/543455/original/file-20230818-15-ys0939.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="diagram of fjord" src="https://images.theconversation.com/files/543455/original/file-20230818-15-ys0939.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/543455/original/file-20230818-15-ys0939.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=278&fit=crop&dpr=1 600w, https://images.theconversation.com/files/543455/original/file-20230818-15-ys0939.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=278&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/543455/original/file-20230818-15-ys0939.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=278&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/543455/original/file-20230818-15-ys0939.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=349&fit=crop&dpr=1 754w, https://images.theconversation.com/files/543455/original/file-20230818-15-ys0939.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=349&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/543455/original/file-20230818-15-ys0939.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=349&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Diagram of a fjord showing a sill that keeps out the warmer ocean water (note in Greenland the fjords are fed by glaciers not rivers).</span>
<span class="attribution"><a class="source" href="https://www.amap.no/">AMAP</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>That’s why mapping these fjords is one of the most critical steps in <a href="https://www.sciencedirect.com/science/article/pii/S2590332220305923">assessing the future</a> of the glaciers that flow into them. This is unfortunately easier said than done, since many of these glaciers flow into some of the most remote areas of the world.</p>
<h2>Ireland-sized glacier, Manhattan-sized icebergs</h2>
<p>The Petermann Glacier – the largest in the northern part of the Greenland ice sheet – drains an area of <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2012GL051634">about 74,000 square kilometres</a>, similar to the size of Ireland.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/543619/original/file-20230821-17-oouuk1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Annotated map of Greenland glaciers" src="https://images.theconversation.com/files/543619/original/file-20230821-17-oouuk1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/543619/original/file-20230821-17-oouuk1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=650&fit=crop&dpr=1 600w, https://images.theconversation.com/files/543619/original/file-20230821-17-oouuk1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=650&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/543619/original/file-20230821-17-oouuk1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=650&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/543619/original/file-20230821-17-oouuk1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=817&fit=crop&dpr=1 754w, https://images.theconversation.com/files/543619/original/file-20230821-17-oouuk1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=817&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/543619/original/file-20230821-17-oouuk1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=817&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Some of the most northerly and inaccessible fjords on earth.</span>
<span class="attribution"><span class="source">Martin Jakobsson</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Petermann is one of a few glaciers around Greenland with a floating ice tongue extending tens of kilometres from where the glacier is grounded on the seafloor. These ice tongues may <a href="https://tc.copernicus.org/articles/7/647/2013/">act as a brakes</a> on the flow of ice into the sea, slowing down mass loss. </p>
<p>In 2010, Petermann made headlines when <a href="https://earthobservatory.nasa.gov/images/45112/ice-island-calves-off-petermann-glacier">a huge chunk broke off</a> and formed an iceberg four times the size of Manhattan island. This was followed by another huge calving two years later. While calving is a natural process, these unusually large events were likely influenced by warmer waters from the Atlantic <a href="https://tos.org/oceanography/article/the-ice-shelf-of-petermann-gletscher-north-greenland-and-its-connection-to">melting the tongue from below</a>, making it thinner and more prone to break. </p>
<p>In 2015 colleagues and I <a href="https://www.nature.com/articles/s41467-018-04573-2">mapped the entire seabed of Petermann Fjord</a> for the first time. We found the entrance was still very deep: 443 metres – as deep as the Empire State Building is tall. Deep enough for that warm, heavy, salty glacier-melting Atlantic water to enter.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/543701/original/file-20230821-27-skrn6s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Ship in front of huge cliffs" src="https://images.theconversation.com/files/543701/original/file-20230821-27-skrn6s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/543701/original/file-20230821-27-skrn6s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/543701/original/file-20230821-27-skrn6s.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/543701/original/file-20230821-27-skrn6s.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/543701/original/file-20230821-27-skrn6s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/543701/original/file-20230821-27-skrn6s.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/543701/original/file-20230821-27-skrn6s.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The icebreaker Oden in Petermann Fjord. The same ship appears as a tiny dot in the image at the top of the article.</span>
<span class="attribution"><span class="source">Martin Jakobsson</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>We next wanted to compare Petermann to the Ryder Glacier to its northeast, which has been more stable since at least the 1950s. Was it kept in place by a shallow fjord entrance keeping out warmer water? </p>
<p>At the time, no ship had ever entered Sherard Osborn Fjord where Ryder Glacier drains, because the sea ice in that region is the toughest in the entire Arctic Ocean. Therefore, nothing at all was known about the seafloor. Ryder Glacier became the target for our next expedition with icebreaker Oden in 2019.</p>
<h2>Shielded from warmer water</h2>
<p>Thick ice in the narrow passage separating Ellesmere Island from Greenland made it hard to even get to Sherard Osborn Fjord. And entering the fjord was a true challenge, as large icebergs that had calved from the ice tongue floated around and occasionally blocked the entire entrance.</p>
<p>It turned out the fjord has a <a href="https://www.nature.com/articles/s43247-020-00043-0">prominent shallow sill in front of Ryder Glacier</a>. This sill shields the glacier from warmer subsurface Atlantic water, which appears to explain why it has behaved very differently compared to Petermann.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/543462/original/file-20230818-25-aktsf8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Annotated image of glacier, fjord and seabed." src="https://images.theconversation.com/files/543462/original/file-20230818-25-aktsf8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/543462/original/file-20230818-25-aktsf8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=409&fit=crop&dpr=1 600w, https://images.theconversation.com/files/543462/original/file-20230818-25-aktsf8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=409&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/543462/original/file-20230818-25-aktsf8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=409&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/543462/original/file-20230818-25-aktsf8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=514&fit=crop&dpr=1 754w, https://images.theconversation.com/files/543462/original/file-20230818-25-aktsf8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=514&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/543462/original/file-20230818-25-aktsf8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=514&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">An underwater sill in front of Ryder Glacier shields it from inflowing warmer water from the Atlantic.</span>
<span class="attribution"><span class="source">Martin Jakobsson</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>The bathymetry of both Petermann and Sherard Osborn fjords has now been incorporated into the <a href="https://seabed2030.org/">Seabed 2030 Project</a>, which aims to completely map the world’s ocean floor before the end of the decade. Knowing more about the seabed, and the glaciers that flow into the sea, will in turn help us to sustainably manage the ocean and, ultimately, the planet. </p>
<p>The are more completely unmapped areas in North Greenland. In 2024, we are planning another expedition with icebreaker Oden even further north to Victoria Fjord, where C.H. Ostenfeld Glacier drains. This glacier recently lost its floating ice tongue and whether or not Atlantic water makes into the fjord remains to be seen. </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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</figure>
<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>Martin Jakobsson is Co-Head of Arctic and North Pacific Center at Seabed 2030, a project funded by the Nippon Foundation to map the entire global seabed.</span></em></p>Some of the world’s biggest glaciers flow into fjords in Greenland and we need to know what they’ll bump into on the seabed.Martin Jakobsson, Professor of Marine Geology and Geophysics, Stockholm UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2110622023-08-04T15:12:17Z2023-08-04T15:12:17ZOne of 2023’s most extreme heatwaves is happening in the middle of winter<figure><img src="https://images.theconversation.com/files/541249/original/file-20230804-21-fsmt9k.png?ixlib=rb-1.1.0&rect=7%2C0%2C2592%2C1446&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Temperature anomaly on Wednesday August 2 2023. Red areas of Chile and northern Argentina are much hotter than the long-term average for this time of year.</span> <span class="attribution"><a class="source" href="https://climatereanalyzer.org/clim/t2_daily/">ClimateReanalyzer.org</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>Temperatures in parts of Chile and northern Argentina have soared to <a href="https://twitter.com/extremetemps/status/1686485331539820545">10°C-20°C above average</a> over the last few days. Towns in the Andes mountains have reached <a href="https://twitter.com/extremetemps/status/1686535219350806528">38°C or more</a>, while Argentina’s capital, Buenos Aires, saw temperatures <a href="https://www.ctvnews.ca/world/a-scorching-winter-argentina-s-capital-breaks-record-for-hottest-start-to-august-in-117-years-1.6503065">above 30°C</a> – breaking its previous August record by more than 5°C. Temperatures peaked at 39°C in the town of <a href="https://twitter.com/SMN_Argentina/status/1687079796692398080">Rivadavia</a>. </p>
<p>Bear in mind it’s mid-winter in this part of the world. And it’s far south enough that seasonal variations have a substantial impact on temperatures. Buenos Aires, for instance, is as far south as Japan, Tibet or Tennessee are north. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1686485331539820545"}"></div></p>
<p>In terms of deviation from temperatures you might expect at a certain place and time of year, this heatwave is comparable to, if not greater than, the recent heatwaves in <a href="https://theconversation.com/european-heatwave-whats-causing-it-and-is-climate-change-to-blame-209653">southern Europe</a>, the US and China. In Vicuña, one of the towns in the Chilean Andes that recently reached 38°C, a typical August day might be <a href="https://weatherspark.com/y/26539/Average-Weather-in-Vicu%C3%B1a-Chile-Year-Round">18°C or so</a> – just imagine it being a whole 20°C warmer than normal wherever you are now.</p>
<p>No wonder some climate scientists have already suggested this could be <a href="https://twitter.com/ClimateDann/status/1687032987135725569">one of the most extreme heatwaves on record</a>.</p>
<h2>What’s causing the extreme heat?</h2>
<p>Over the past six days, a persistent area of high pressure, or anticyclone, has lingered to the east of the Andes. Also known as a “blocking high”, this appears to be the key driver of the intense heat. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/541258/original/file-20230804-25-f3znn9.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Annotated map of South America" src="https://images.theconversation.com/files/541258/original/file-20230804-25-f3znn9.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/541258/original/file-20230804-25-f3znn9.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=409&fit=crop&dpr=1 600w, https://images.theconversation.com/files/541258/original/file-20230804-25-f3znn9.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=409&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/541258/original/file-20230804-25-f3znn9.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=409&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/541258/original/file-20230804-25-f3znn9.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=514&fit=crop&dpr=1 754w, https://images.theconversation.com/files/541258/original/file-20230804-25-f3znn9.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=514&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/541258/original/file-20230804-25-f3znn9.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=514&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 blocking anticyclone driving the Chile-Argentina heatwave.</span>
<span class="attribution"><span class="source">GFS analysis data</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Blocking anticyclones can drive heatwaves in three main ways. Firstly, they pull warmer air from closer to the equator towards them. The system also compresses and traps the air, heating it up, as was the case for the <a href="https://www.nature.com/articles/s41467-023-36289-3">2021 heatwave in the Pacific Northwest</a>, which shattered the Canadian temperature record by nearly 5°C. Finally, the high pressure means there is little ascending air and hence little cloud cover. This allows the sun to heat the land continuously during the day, <a href="https://www.sciencedirect.com/science/article/pii/S0169809515001738?via%3Dihub">building up heat</a>.</p>
<p>However, scientists need to analyse the meteorology of this unprecedented event in more detail to gain a more complete understanding.</p>
<h2>El Niño made this more likely</h2>
<p>The Chile-Argentina heatwave may have been made more likely by the <a href="https://theconversation.com/what-el-nino-means-for-the-worlds-perilous-climate-tipping-points-209083">developing El Niño</a> in the Pacific Ocean. El Niño events, which typically occur every four years or so, are characterised by warm sea surface temperatures in the central-to-eastern tropical Pacific. Temperatures in the central Pacific are currently <a href="https://www.metoffice.gov.uk/research/climate/seasonal-to-decadal/gpc-outlooks/el-nino-la-nina">about 1°C above average</a> for the time of year.</p>
<p>These warmer ocean temperatures make air more buoyant over the central Pacific, causing the air to rise. This drives changes to atmospheric circulation patterns further afield. El Niño-induced changes to atmospheric circulation typically mean higher pressure and warmer winter temperatures for <a href="https://adgeo.copernicus.org/articles/22/3/2009/adgeo-22-3-2009.pdf">this part of South America</a>.</p>
<h2>Climate change made it worse</h2>
<p>The blocking system driving the extreme heat would probably have led to warm temperatures even in the absence of anthropogenic climate change. However, the rapid warming of climate change allowed the heatwave to become truly unprecedented.</p>
<p>Climate scientists expect to see <a href="https://www.science.org/doi/full/10.1126/sciadv.abm6860">temperature records broken</a> as our planet continues to heat up. This is because the distribution of possible temperatures is shifting higher and higher.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/541251/original/file-20230804-29-96u3yl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Annotated graph" src="https://images.theconversation.com/files/541251/original/file-20230804-29-96u3yl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/541251/original/file-20230804-29-96u3yl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=474&fit=crop&dpr=1 600w, https://images.theconversation.com/files/541251/original/file-20230804-29-96u3yl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=474&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/541251/original/file-20230804-29-96u3yl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=474&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/541251/original/file-20230804-29-96u3yl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=596&fit=crop&dpr=1 754w, https://images.theconversation.com/files/541251/original/file-20230804-29-96u3yl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=596&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/541251/original/file-20230804-29-96u3yl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=596&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">An increase in averages means an increase in extremes.</span>
<span class="attribution"><span class="source">Australia Climate Commission/IPCC</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Chile has already experienced the effects of climate change recently through a severe heatwave in February – late summer – resulting in several deaths from <a href="https://apnews.com/article/wildfires-latin-america-caribbean-climate-and-environment-fires-f1eaf0919c9b9b9d1f88d60be2191d78">wildfires</a>, as well as a decade-long <a href="https://www.theguardian.com/world/2022/jun/01/chiles-water-crisis-megadrought-reaching-breaking-point">mega-drought</a>. The country recently <a href="https://www.climatechangenews.com/2022/09/05/gigantic-missed-opportunity-chile-rejects-green-constitution-faces-uncertainty/">rejected</a> a rewrite of the constitution which would have mandated its government to take action against the nature and climate crises.</p>
<h2>The longer-term impact of a winter heatwave</h2>
<p>The hottest temperatures now appear to have largely subsided in the Andes. However, temperatures are still well above average for northern Argentina, Bolivia and Paraguay, and will remain so for the next five days or so.</p>
<p>The impacts of winter heatwaves are less well understood than summer heatwaves. For Chile, the most likely impact is on <a href="https://www.wionews.com/world/climate-change-chile-argentina-face-scorching-heat-wave-in-middle-of-winter-621920">snowpack in the mountains</a>, which provides water for <a href="https://earthobservatory.nasa.gov/images/150100/snow-blanket-for-the-andes">drinking, agriculture and power generation</a>. Any melting of the snowpack will probably also affect the diverse flora and fauna found in the Andes.</p>
<p>Overall, this heatwave is a startling reminder of how humans are changing Earth’s climate. We will continue to see such unprecedented extremes until we stop burning fossil fuels and emitting greenhouse gases into the atmosphere.</p>
<hr>
<figure class="align-right ">
<img alt="Imagine weekly climate newsletter" src="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
</figcaption>
</figure>
<p><strong><em>Don’t have time to read about climate change as much as you’d like?</em></strong>
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<p class="fine-print"><em><span>Matthew Patterson receives funding from the Natural Environment Research Council.</span></em></p>Parts of Argentina and the Chilean Andes experienced some of their highest temperatures on record.Matthew Patterson, Postdoctoral Research Assistant in in Atmospheric Physics, University of OxfordLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2108462023-08-02T16:53:32Z2023-08-02T16:53:32ZScience shows the severe climate consequences of new fossil fuel extraction<figure><img src="https://images.theconversation.com/files/540723/original/file-20230802-29-p10zec.jpg?ixlib=rb-1.1.0&rect=1086%2C0%2C4904%2C3997&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">An offshore drilling platform.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/sea-drilling-platform-650001655">Mike Mareen/Shutterstock</a></span></figcaption></figure><p>The world has just suffered through its <a href="https://www.theguardian.com/science/2023/jul/27/scientists-july-world-hottest-month-record-climate-temperatures">warmest month ever recorded</a>. Heatwaves have swept across <a href="https://public.wmo.int/en/media/news/heatwaves-wildfires-mark-summer-of-extremes">southern Europe, the US and China</a>, breaking many temperature records in the process. </p>
<p>Climate scientists have been sounding the alarm <a href="https://www.ipcc.ch/report/ar3/wg1/">for decades</a> that this type of event will become more frequent as the world continues to warm. The major culprit behind this is the burning of fossil fuels. So it’s extremely concerning that the UK government <a href="https://www.gov.uk/government/news/hundreds-of-new-north-sea-oil-and-gas-licences-to-boost-british-energy-independence-and-grow-the-economy-31-july-2023">has announced</a> its intention to grant hundreds of licences for new North Sea oil and gas extraction.</p>
<p>Although burning fossil fuels to generate power and heat has enabled society to develop and flourish, we are now experiencing the unintended side effects. The carbon dioxide that has been added to the atmosphere is <a href="https://www.ipcc.ch/report/ar6/wg1/chapter/summary-for-policymakers/">leading to a rise</a> in global temperatures, causing heatwaves to become hotter and downpours more intense. The resulting large-scale disruption and suffering is becoming ever more visible. </p>
<p>This warming will continue, with worsening climatic consequences, until we reduce global carbon dioxide emissions to “net zero”. After that, we will still have to live and suffer in a warmer climate for generations. The collective choices we make now will matter in the future.</p>
<p>The small-scale, but high-profile, <a href="https://www.theguardian.com/environment/2023/apr/05/just-stop-oil-activists-convicted-obstructing-highway-london">disruptions caused by Just Stop Oil protesters</a> in the UK are extremely frustrating for many. But their single demand – for no licenses for new UK coal, oil and gas projects – is consistent with the science underpinning the international agreements that the UK has signed. </p>
<h2>Temperatures are rising</h2>
<p>Since the 1860s, the scientific community <a href="https://www.rigb.org/explore-science/explore/blog/who-discovered-greenhouse-effect">has understood</a> that adding more carbon dioxide to the atmosphere would warm the climate. And as long ago as 1938, the burning of fossil fuels was <a href="https://www.theguardian.com/environment/blog/2013/apr/22/guy-callendar-climate-fossil-fuels">linked</a> to the observed rise in both carbon dioxide levels and global temperatures. Fast forward to now and global temperatures are warmer, and increasing faster, than at any point in human civilisation.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1686479519438254080"}"></div></p>
<p>In response to the overwhelming scientific evidence, the UK and 193 other nations came together in 2015 to ratify the <a href="https://www.un.org/en/climatechange/paris-agreement">Paris agreement on climate change</a>. One of the agreed goals is to limit global warming to well below 2°C, and even aim for 1.5°C, compared to the pre-industrial era. </p>
<p>However, the latest <a href="https://www.ipcc.ch/report/ar6/syr/downloads/report/IPCC_AR6_SYR_SPM.pdf">synthesis report</a> from the Intergovernmental Panel on Climate Change, which all governments explicitly endorsed, paints a stark reality. If we burn all of the fossil fuels that we currently have access to, then global warming will exceed 1.5°C and may reach 2°C. </p>
<p>To avoid breaching the limits set out by the Paris agreement, some of the coal, oil and gas that we can already extract must remain unburnt. New fossil fuel extraction projects will make it even harder to stop further global warming. </p>
<h2>Build up renewable infrastructure</h2>
<p>There are other options. The UK government’s official advisers, the Climate Change Committee, have put forward a vision for UK power generation consistent with a net zero future. They <a href="https://www.theccc.org.uk/publication/delivering-a-reliable-decarbonised-power-system/">say that</a> the UK could provide all of its energy needs by 2050 through a combination of renewables, bioenergy, nuclear, hydrogen, storage and demand management, with some carbon capture and storage for fossil gas-based generation in the meantime.</p>
<figure class="align-center ">
<img alt="A family walking dogs on a beach in front of an offshore wind farm." src="https://images.theconversation.com/files/540725/original/file-20230802-17-i9629h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/540725/original/file-20230802-17-i9629h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=323&fit=crop&dpr=1 600w, https://images.theconversation.com/files/540725/original/file-20230802-17-i9629h.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=323&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/540725/original/file-20230802-17-i9629h.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=323&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/540725/original/file-20230802-17-i9629h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=406&fit=crop&dpr=1 754w, https://images.theconversation.com/files/540725/original/file-20230802-17-i9629h.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=406&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/540725/original/file-20230802-17-i9629h.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=406&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The UK can achieve energy security without causing additional global warming.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/wind-farm-off-coast-yarmouth-family-1216647160">Nigel Jarvis/Shutterstock</a></span>
</figcaption>
</figure>
<p>If the UK followed the example of China and <a href="https://www.reuters.com/markets/commodities/china-widens-renewable-energy-supply-lead-with-wind-power-push-2023-03-01/">rapidly increased</a> its investments in renewable energy, then it could achieve energy security without causing additional global warming. China emits the <a href="https://ourworldindata.org/co2-emissions">most carbon dioxide</a> of any country in the world. But it is installing more <a href="https://www.forbes.com/sites/davidrvetter/2022/01/26/china-built-more-offshore-wind-in-2021-than-every-other-country-built-in-5-years/">renewable energy generation</a> than the rest of the world combined.</p>
<p>Rapidly reducing our reliance on fossil fuels, and not issuing new licenses to extract oil and gas, is the most effective way of minimising future climate-related disruptions. The sooner those with the power to shape our future recognise this, the better.</p>
<hr>
<figure class="align-right ">
<img alt="Imagine weekly climate newsletter" src="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
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<p><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>Ed Hawkins receives funding from the Natural Environment Research Council.</span></em></p>More than a century of research shows that burning fossil fuels warms the climate – that’s exactly why granting new North Sea oil and gas licenses is a bad idea.Ed Hawkins, Professor of Climate Science, University of ReadingLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2105702023-07-28T16:24:22Z2023-07-28T16:24:22ZThe Atlantic is at risk of circulation collapse – it would mean even greater climate chaos across Europe<figure><img src="https://images.theconversation.com/files/539958/original/file-20230728-3774-595wvj.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C4265%2C2833&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">andrejs polivanovs / shutterstock</span></span></figcaption></figure><p>Amid news of lethal heatwaves across the Northern Hemisphere comes the daunting prospect of a climate disaster on an altogether grander scale. New findings published in <a href="https://www.nature.com/articles/s41467-023-39810-w">Nature Communications</a> suggest the Atlantic meridional overturning circulation, or Amoc, could collapse within the next few decades – maybe even within the next few years – driving European weather to even greater extremes.</p>
<p>The Amoc amounts to a system of currents in the Atlantic that bring warm water northwards where it then cools and sinks. It is a key reason why Europe’s climate has been stable for thousands of years, even if it’s hard to recognise this chaotic summer as part of that stability. </p>
<p>There is much uncertainty in these latest predictions and some scientists are <a href="https://www.bbc.co.uk/news/science-environment-66289494">less convinced</a> a collapse is imminent. Amoc is also only one part of the wider Gulf Stream system, much of which is driven by winds that will continue to blow even if the Amoc collapses. So part of the Gulf Stream will survive an Amoc collapse.</p>
<p>But I have studied the links between <a href="https://scholar.google.com/citations?user=xflmVSMAAAAJ&hl=en">Atlantic currents and the climate</a> for decades now, and know that an Amoc collapse would still lead to even greater climate chaos across Europe and beyond. At minimum, it is a risk worth being aware of.</p>
<h2>Amoc helps keep Europe warm and stable</h2>
<p>To appreciate how much Amoc influences the climate in the northeast Atlantic, consider how much warmer north Europeans feel compared to people at similar latitudes elsewhere. The following maps show how surface air temperatures depart from the average at each latitude and highlight patterns of warm and cool spots around the planet:</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/539777/original/file-20230727-25-mkqjxk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/539777/original/file-20230727-25-mkqjxk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/539777/original/file-20230727-25-mkqjxk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=720&fit=crop&dpr=1 600w, https://images.theconversation.com/files/539777/original/file-20230727-25-mkqjxk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=720&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/539777/original/file-20230727-25-mkqjxk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=720&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/539777/original/file-20230727-25-mkqjxk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=905&fit=crop&dpr=1 754w, https://images.theconversation.com/files/539777/original/file-20230727-25-mkqjxk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=905&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/539777/original/file-20230727-25-mkqjxk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=905&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Surface air temperature departure from 1948-2018 zonal average in January (top) and July (bottom).</span>
<span class="attribution"><a class="source" href="https://www.sciencedirect.com/book/9780128160596/ocean-currents">Marsh & van Sebille, 2021; Data: NCEP/NCAR</a>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Most striking in the northern winter (January) is a red spot centred to the west of Norway where temperatures are 20°C warmer than the latitude average, thanks to Amoc. The northeast Pacific – and therefore western Canada and Alaska – enjoys a more modest 10°C warming from a similar current, while prevailing westerly winds mean the northwest Atlantic and northwest Pacific are much colder, as are the adjacent land masses of eastern Canada and Siberia.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/539774/original/file-20230727-23-fw7bkx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Norwegian town beside sea, snowy mountain in background" src="https://images.theconversation.com/files/539774/original/file-20230727-23-fw7bkx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/539774/original/file-20230727-23-fw7bkx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/539774/original/file-20230727-23-fw7bkx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/539774/original/file-20230727-23-fw7bkx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/539774/original/file-20230727-23-fw7bkx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/539774/original/file-20230727-23-fw7bkx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/539774/original/file-20230727-23-fw7bkx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Lofoten, Norway, is beyond the Arctic Circle yet most days are above freezing even in midwinter. Relative to latitude, it’s one of the world’s warmest places.</span>
<span class="attribution"><span class="source">Dmitry Rukhlenko / shutterstock</span></span>
</figcaption>
</figure>
<p>The weather and climate of Europe, and northern Europe in particular, is highly variable from day to day, week to week and year to year, with competing air masses (warm and moist, cold and dry, and so on) gaining or losing influence, often guided by the high-altitude jet stream. Changes in weather and climate can be triggered by events located far away – and over the ocean.</p>
<h2>How ocean temperatures are linked to weather</h2>
<p>Over recent years Europe has witnessed some particularly unusual weather, in both winter and summer. At the same time, <a href="https://theconversation.com/weird-weather-blame-the-north-atlantic-53271">peculiar patterns of sea surface temperatures</a> have appeared across the North Atlantic. Across great swathes of the ocean from the tropics to the Arctic, temperatures have persisted 1°C-2°C above or below normal levels, for months or even years on end. These patterns appear to exert a strong influence on the atmosphere, even influencing the path and strength of the <a href="https://theconversation.com/britains-recent-wet-summers-can-be-blamed-on-the-atlantic-jet-stream-says-new-study-64337">jet stream</a>. </p>
<p>To an extent, we can attribute some of these sea surface temperature patterns to a changing Amoc, but it’s often not that straightforward. Nevertheless, the association of extreme seasons and weather with unusual sea temperatures might give us an idea of how a collapsed Amoc would unsettle the status quo. Here are three examples.</p>
<p>Northern Europe experienced successive severe winters in 2009/10 and 2010/11, subsequently attributed to a <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2011GL048978">brief slowdown of the Amoc</a>. At the same time heat had built up in the tropics, fuelling an <a href="https://www.nature.com/articles/s41467-019-08496-4">unusually active June-November hurricane season</a> in 2010.</p>
<p>In the mid 2010s a “cold blob” formed in the North Atlantic, reaching its most extreme in the summer of 2015 when it coincided with <a href="https://iopscience.iop.org/article/10.1088/1748-9326/11/7/074004/meta">heatwaves in central Europe</a> and was one of the only parts of the world cooler than its long-term average. </p>
<p>The cold blob looked suspiciously like the fingerprint of a weakened Amoc, but colleagues and I subsequently attributed this transient episode to <a href="https://www.annualreviews.org/doi/10.1146/annurev-marine-121916-063102">more local atmospheric influences</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/539944/original/file-20230728-24473-ud8ybo.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Shaded world map" src="https://images.theconversation.com/files/539944/original/file-20230728-24473-ud8ybo.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/539944/original/file-20230728-24473-ud8ybo.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/539944/original/file-20230728-24473-ud8ybo.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/539944/original/file-20230728-24473-ud8ybo.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/539944/original/file-20230728-24473-ud8ybo.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/539944/original/file-20230728-24473-ud8ybo.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/539944/original/file-20230728-24473-ud8ybo.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Spot the blob: temperatures in 2015 – at the time, the warmest year on record – compared to long-term averages.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Cold_blob#/media/File:16-008-NASA-2015RecordWarmGlobalYearSince1880-20160120.png">NASA/NOAA</a></span>
</figcaption>
</figure>
<p>In 2017, the tropical Atlantic was again warmer than average and once again an unusually active hurricane season ensued, although the Amoc was not as clearly involved <a href="https://www.nature.com/articles/s41467-019-08496-4">as 2010</a>. Extensive warmth to the northeast in late 2017 may have sustained hurricane Ophelia, emerging around the Azores and making landfall in Ireland in October.</p>
<p>Based on just these few examples, we can expect that a more substantial reorganisation of North Atlantic surface temperatures will have profound consequences for the climate in Europe and beyond. </p>
<p>Larger ocean temperature extremes may alter the character of weather systems that are powered by heat and moisture from the sea – when and where temperatures rise beyond current extremes, Atlantic storms may grow <a href="https://theconversation.com/hurricane-ian-how-climate-change-is-making-north-atlantic-tropical-storms-worse-191547">more destructive</a>. More extreme ocean temperature patterns may exert further influences on tropical hurricane tracks and the jet stream, sending storms to <a href="https://theconversation.com/why-ex-hurricane-ophelia-took-a-wrong-turn-towards-ireland-and-britain-and-carried-all-that-dust-85851">ever more unlikely destinations</a>.</p>
<p>If the Amoc collapses we can expect larger extremes of heat, cold, drought and flooding, a range of “surprises” to exacerbate the current climate emergency. The potential climate impacts – on Europe in particular – should add urgency to our decision-making.</p>
<hr>
<figure class="align-right ">
<img alt="Imagine weekly climate newsletter" src="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
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<p class="fine-print"><em><span>Robert Marsh receives funding from the UK Natural Environment Research Council. </span></em></p>Expect more extremes and a range of ‘surprises’ to exacerbate the climate emergency.Robert Marsh, Professor of Oceanography and Climate, University of SouthamptonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2080522023-06-20T13:51:07Z2023-06-20T13:51:07ZAn ‘extreme’ heatwave has hit the seas around the UK and Ireland – here’s what’s going on<figure><img src="https://images.theconversation.com/files/532919/original/file-20230620-5801-5u3n7d.png?ixlib=rb-1.1.0&rect=0%2C0%2C1375%2C714&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Sea surface temperature anomaly around the UK and Ireland, June 18 2023. Areas in dark red are 5°C warmer than usual.</span> <span class="attribution"><a class="source" href="https://coralreefwatch.noaa.gov/product/vs/map_full.html?lat=48.239370597945936&lng=351.20653253084697&zoom_level=2">NOAA / Google Maps</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>One of the most severe marine heatwaves on the planet is taking place in the shallow seas around the UK and Ireland. That’s according to the US National Oceanic and Atmospheric Administration (NOAA), which has labelled this a “Category 4” heatwave. Rarely used outside of the tropics, a cat 4 heatwave means “extreme” heat.</p>
<p>Marine heatwaves are <a href="https://coralreefwatch.noaa.gov/product/marine_heatwave/">classified as</a> “prolonged periods of anomalously high sea surface temperature”, when compared to the long-term average for that time of year. And thanks to measurements made by satellites orbiting the earth we know that, in some areas around the UK, surface water temperatures are 4°C to 5°C above normal for mid June. </p>
<p>This is extremely unusual: buoys around Ireland and the UK have been recording sea surface temperature for over 20 years, and in that time it has never been this hot this early in the summer. </p>
<p>The heatwave is strongest in the northern North Sea, northwest of Ireland, and the Celtic Sea between Cornwall and southern Ireland. However, in other areas, such as the southern North Sea, the English Channel and the southern Irish Sea, the surface temperatures are only a degree or so above normal.</p>
<p>The two regions are <a href="https://research.bangor.ac.uk/portal/en/researchoutputs/tides-the-moon-and-the-kaleidoscope-of-ocean-mixing(7af72d26-81fd-456f-87fc-a771a58d4673).html">very different in oceanographic terms</a>. The latter areas tend to be shallower (30-40 metres) with stronger tidal currents and so the water remains well mixed from the surface to the sea bed, all year around. In contrast, the regions where the heatwave is strongest are deeper (80-100 metres) with weaker tidal currents. As the mixing is weaker these seas “stratify” each summer, with a layer of warmer water overlying the cooler deeper layer.</p>
<p>In these seasonally stratifying regions the heat from the sun only warms the relatively shallow surface layer, while in the mixed regions the sun’s impact is diluted as its heat is mixed through the ocean from seabed to surface.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1670181977067241472"}"></div></p>
<h2>Oceans are slow to warm up and cool down</h2>
<p>The temperature of the atmosphere can vary a lot day to day. You might find yourself wearing a jumper on Monday but shorts and a t-shirt by Wednesday. But oceans are different – their ability to absorb lots of heat means temperature varies slowly and extremes are rare. </p>
<p>In <a href="https://www.mccip.org.uk/sites/default/files/2022-11/Stratification.pdf">seasonally stratified regions</a> the stratification starts to develop in late May, with the maximum sea surface temperatures happening in August. At these locations you would still only expect the temperature to vary by 10°C or so over the whole year (in contrast with the atmosphere where such shifts happen in a matter of hours). </p>
<p>In this latest heatwave, the sea surface is up to 5°C warmer than normal two months before we’d expect to see the maximum temperatures. </p>
<p><strong>North Atlantic temperature patterns</strong></p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/532921/original/file-20230620-8426-normee.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Graph of sea surface temperatures" src="https://images.theconversation.com/files/532921/original/file-20230620-8426-normee.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/532921/original/file-20230620-8426-normee.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=382&fit=crop&dpr=1 600w, https://images.theconversation.com/files/532921/original/file-20230620-8426-normee.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=382&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/532921/original/file-20230620-8426-normee.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=382&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/532921/original/file-20230620-8426-normee.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=480&fit=crop&dpr=1 754w, https://images.theconversation.com/files/532921/original/file-20230620-8426-normee.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=480&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/532921/original/file-20230620-8426-normee.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=480&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Across the North Atlantic, the sea surface is warming faster than ever before (thick black line = 2023; orange = 2022; grey lines = 1981-2019)</span>
<span class="attribution"><a class="source" href="https://climatereanalyzer.org/clim/sst_daily/">NOAA / climatereanalyzer.org</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>I would speculate part of the reason for these anomalously high temperatures in stratified seas is that the surface layer is shallower than usual and so the sun’s heat is more concentrated (probably a result of relatively stable weather and lack of Atlantic storms crossing the UK in the past month). As such, these <a href="https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2022GL100448">already very warm areas will warm further</a> until a sufficiently strong storm comes along and mixes the heat down into a thicker surface layer.</p>
<h2>Fish may go hungry</h2>
<p>One reason this heatwave is so significant is because those stratified seas on the continental shelf around Britain and Ireland are some of the most biologically productive on the planet. They have long been an important area for fishing cod, haddock, mackerel and other species. Those fish eat smaller fish and crustaceans, which in turn feed on microscopic plants known as plankton. </p>
<p>At this time of year, these plankton are dependent on nutrients mixed up from the deep water into the surface layer. However, this year, this nutrient supply may be diminished, since the very high surface temperature means there is likely <a href="https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2022GL100448">stronger stratification and less mixing</a>. </p>
<p>A heatwave on the surface could potentially harm the deeper ocean too, and the fish that live there. These continental shelf seas are already suffering from a <a href="https://nora.nerc.ac.uk/id/eprint/527795/1/02_oxygen_2020.pdf">decline in deep water oxygen</a>, which is partly offset by mixing oxygen-rich water from the surface. However, the fact that the surface temperatures are so high point to a lack of mixing between the layers, and in any case, warmer water contains less oxygen.</p>
<p>On a slightly longer timescale, we already know that climate change is <a href="https://www.mccip.org.uk/sites/default/files/2021-07/16_fish_2020.pdf">affecting these seas</a>. Some warm water fish species are appearing in UK waters for instance, and native fish reproduction cycles and those of the plankton they feed on are no longer in perfect sync. This extreme heatwave may be a sign of further changes to come. </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>Tom Rippeth 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>A thin layer of surface water has been baked by the sun.Tom Rippeth, Professor of Physical Oceanography, Bangor UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2069742023-06-06T15:16:21Z2023-06-06T15:16:21ZArctic Ocean could be ice-free in summer by 2030s, say scientists – this would have global, damaging and dangerous consequences<figure><img src="https://images.theconversation.com/files/530135/original/file-20230605-19-ykkaxt.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C4259%2C2839&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Ice in the Chukchi Sea, north of Alaska and Siberia. </span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/gsfc/7348953774/">NASA Goddard Space Flight Center</a></span></figcaption></figure><p>The Arctic Ocean could be ice-free in summer by the 2030s, even if we do a good job of reducing emissions between now and then. That’s the worrying conclusion of a new study in <a href="https://www.nature.com/articles/s41467-023-38511-8">Nature Communications</a>. </p>
<p>Predictions of an ice-free Arctic Ocean have a long and complicated history, and the 2030s is sooner than most scientists had thought possible (though it is later than some had wrongly forecast). What we know for sure is the disappearance of sea ice at the top of the world would not only be an emblematic sign of climate breakdown, but it would have global, damaging and dangerous consequences. </p>
<p>The Arctic has been experiencing climate heating <a href="https://theconversation.com/arctic-is-warming-nearly-four-times-faster-than-the-rest-of-the-world-new-research-188474">faster than any other part of the planet</a>. As it is at the frontline of climate change, the eyes of many scientists and local indigenous people have been on the sea ice that covers much of the Arctic Ocean in winter. This thin film of frozen seawater expands and contracts with the seasons, reaching a minimum area in September each year. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/530136/original/file-20230605-19-mdh85y.gif?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Animation of Arctic sea ice from space" src="https://images.theconversation.com/files/530136/original/file-20230605-19-mdh85y.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/530136/original/file-20230605-19-mdh85y.gif?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=184&fit=crop&dpr=1 600w, https://images.theconversation.com/files/530136/original/file-20230605-19-mdh85y.gif?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=184&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/530136/original/file-20230605-19-mdh85y.gif?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=184&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/530136/original/file-20230605-19-mdh85y.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=232&fit=crop&dpr=1 754w, https://images.theconversation.com/files/530136/original/file-20230605-19-mdh85y.gif?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=232&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/530136/original/file-20230605-19-mdh85y.gif?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=232&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Arctic sea ice grows until March and then shrinks until September.</span>
<span class="attribution"><a class="source" href="https://www.nasa.gov/feature/esnt/2022/nasa-finds-2022-arctic-winter-sea-ice-10th-lowest-on-record">NASA</a></span>
</figcaption>
</figure>
<p>The ice which remains at the end of summer is called multiyear sea ice and is considerably thicker than its seasonal counterpart. It acts as barrier to the transfer of both moisture and heat between the ocean and atmosphere. Over the past 40 years this multiyear sea ice has shrunk from around <a href="http://polarportal.dk/en/sea-ice-and-icebergs/sea-ice-extent0/">7 million sq km to 4 million</a>. That is a loss equivalent to roughly the size of India or 12 UKs. In other words, it’s a big signal, one of the most stark and dramatic signs of fundamental change to the climate system anywhere in the world.</p>
<p>As a consequence, there has been considerable effort invested in determining when the Arctic Ocean might first become ice-free in summer, sometimes called a “blue ocean event” and defined as when the sea ice area drops below 1 million sq kms. This threshold is used mainly because older, thicker ice along parts of Canada and northern Greenland is expected to remain long after the rest of the Arctic Ocean is ice-free. We can’t put an exact date on the last blue ocean event, but one in the near future would likely mean open water at the North Pole for the first time in <a href="https://www.nature.com/articles/nature10581">thousands of years</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/530138/original/file-20230605-29-9uuhxu.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Annotated map of Arctic" src="https://images.theconversation.com/files/530138/original/file-20230605-29-9uuhxu.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/530138/original/file-20230605-29-9uuhxu.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=712&fit=crop&dpr=1 600w, https://images.theconversation.com/files/530138/original/file-20230605-29-9uuhxu.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=712&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/530138/original/file-20230605-29-9uuhxu.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=712&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/530138/original/file-20230605-29-9uuhxu.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=895&fit=crop&dpr=1 754w, https://images.theconversation.com/files/530138/original/file-20230605-29-9uuhxu.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=895&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/530138/original/file-20230605-29-9uuhxu.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=895&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 thickest ice (highlighted in pink) is likely to remain even if the North Pole is ice-free.</span>
<span class="attribution"><a class="source" href="https://nsidc.org/arcticseaicenews/2015/05/new-tools-for-sea-ice-thickness/">NERC Center for Polar Observation and Modelling</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>One problem with predicting when this might occur is that sea ice is notoriously difficult to model because it is influenced by both atmospheric and oceanic circulation as well as the flow of heat between these two parts of the climate system. That means that the climate models – powerful computer programs used to simulate the environment – need to get all of these components right to be able to accurately predict changes in sea ice extent. </p>
<h2>Melting faster than models predicted</h2>
<p>Back in the 2000s, an assessment of early generations of climate models found they generally <a href="https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2007GL029703">underpredicted the loss of sea ice</a> when compared to satellite data showing what actually happened. The models predicted a loss of about 2.5% per decade, while the observations were closer to 8%. </p>
<p>The next generation of models did better but were <a href="https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2012GL052676">still not matching observations</a> which, at that time were suggesting a blue ocean event would happen by mid-century. Indeed, the latest <a href="https://www.ipcc.ch/report/sixth-assessment-report-working-group-i/">IPCC climate science report</a>, published in 2021, reaches a similar conclusion about the timing of an ice-free Arctic Ocean. </p>
<p>As a consequence of the problems with the climate models, some scientists have attempted to extrapolate the observational record resulting in the controversial and, ultimately, incorrect assertion that this would happen <a href="https://www.theguardian.com/environment/2016/aug/21/arctic-will-be-ice-free-in-summer-next-year">during the mid 2010s</a>. This did not help the credibility of the scientific community and its ability to make reliable projections.</p>
<h2>Ice-free by 2030?</h2>
<p>The scientists behind the latest study have taken a different approach by, in effect, calibrating the models with the observations and then using this calibrated solution to project sea ice decline. This makes a lot of sense, because it reduces the effect of small biases in the climate models that can in turn bias the sea ice projections. They call these “observationally constrained” projections and find that the Arctic could become ice-free in summer as early as 2030, even if we do a good job of reducing emissions between now and then.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/530365/original/file-20230606-21-usmovg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Walruses on ice floe" src="https://images.theconversation.com/files/530365/original/file-20230606-21-usmovg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/530365/original/file-20230606-21-usmovg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=394&fit=crop&dpr=1 600w, https://images.theconversation.com/files/530365/original/file-20230606-21-usmovg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=394&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/530365/original/file-20230606-21-usmovg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=394&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/530365/original/file-20230606-21-usmovg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=495&fit=crop&dpr=1 754w, https://images.theconversation.com/files/530365/original/file-20230606-21-usmovg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=495&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/530365/original/file-20230606-21-usmovg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=495&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Walruses depend on sea ice. As it melts, they’re being forced onto land.</span>
<span class="attribution"><span class="source">outdoorsman / shutterstock</span></span>
</figcaption>
</figure>
<p>There is still plenty of uncertainty around the exact date – about <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2016GL070067">20 years or so</a> – because of natural chaotic fluctuations in the climate system. But compared to previous research, the new study still brings forward the most likely timing of a blue ocean event by about a decade.</p>
<h2>Why this matters</h2>
<p>You might be asking the question: so what? Other than some polar bears not being able to hunt in the same way, why does it matter? Perhaps there are even benefits as the previous US secretary of state, Mike Pompeo, <a href="https://edition.cnn.com/2019/05/06/politics/pompeo-sea-ice-arctic-council/index.html">once declared</a> – it means ships from Asia can potentially save around 3,000 miles of journey to European ports in summer at least. </p>
<p>But Arctic sea ice is an important component of the climate system. As it dramatically reduces the amount of sunlight absorbed by the ocean, removing this ice is predicted to further accelerate warming, through a process known as a positive feedback. This, in turn, will make the Greenland ice sheet <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2014GL059770">melt faster</a>, which is already a major contributor to <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2021RG000757">sea level rise</a>. </p>
<p>The loss of sea ice in summer would also mean changes in <a href="https://www.ipcc.ch/report/ar6/wg2/chapter/ccp6/">atmospheric circulation and storm tracks</a>, and fundamental shifts in ocean biological activity. These are just some of the <a href="https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2021RG000757">highly undesirable consequences</a> and it is fair to say that the disadvantages will far outweigh the slender benefits. </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>Jonathan Bamber receives funding from the UK Natural Environment and Engineering and Physical Sciences Research Councils, the European Commission, the European Research Council and the European Space Agency. </span></em></p>A short history of predicting an ice-free Arctic – and why you should listen to this one.Jonathan Bamber, Professor of Physical Geography, University of BristolLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2050092023-05-23T12:27:30Z2023-05-23T12:27:30ZMore than two dozen cities and states are suing Big Oil over climate change – they just got a boost from the US Supreme Court<p>Honolulu has lost <a href="https://s3.documentcloud.org/documents/6801979/Honolulu-Climate-Lawsuit-3-9-2020.pdf">more than 5 miles</a> of its famous beaches to sea level rise and storm surges. Sunny-day flooding during high tides makes many city roads impassable, and water mains for the public drinking water system are corroding from saltwater because of sea level rise.</p>
<p>The damage has left the city and county spending millions of dollars on repairs and infrastructure to try to adapt to the rising risks.</p>
<p>Future costs will almost certainly be higher. More than US$19 billion in property value, at today’s dollars, is at risk by 2100 from projected sea level rise, driven by greenhouse gas emissions largely from the burning of fossil fuels. Elsewhere in Honolulu County, which covers all of Oahu, many coastal communities will be cut off or uninhabitable.</p>
<p>Unwilling to have their taxpayers bear the full brunt of these costs, the <a href="https://s3.documentcloud.org/documents/6801979/Honolulu-Climate-Lawsuit-3-9-2020.pdf">city and county sued</a> Sunoco LP, Exxon Mobil Corp. and other big oil companies in 2020.</p>
<p>Their case – one of <a href="https://climateintegrity.org/cases">more than two dozen</a> involving <a href="https://images.theconversation.com/files/527655/original/file-20230523-14019-49gxsv.png">U.S. cities, counties and states suing the oil industry</a> over climate change – just got a break from the U.S. Supreme Court. That has significantly increased their odds of succeeding.</p>
<h2>Suing over the cost of climate change</h2>
<p>At stake in all of these cases is who pays for the staggering cost of a changing climate.</p>
<p>Local and state governments that are suing want to hold the major oil companies responsible for the costs of responding to disasters that scientists are increasingly <a href="https://news.climate.columbia.edu/2021/10/04/attribution-science-linking-climate-change-to-extreme-weather/">able to attribute</a> to climate disruption and <a href="https://doi.org/10.1088/1748-9326/acbce8">tie back to the fossil fuel industry</a>. Several of the plaintiffs accuse the companies of lying to the public about their products’ risks in violation of state or local consumer protection laws that prohibit false advertising.</p>
<p><iframe id="j1ckJ" class="tc-infographic-datawrapper" src="https://datawrapper.dwcdn.net/j1ckJ/20/" height="400px" width="100%" style="border: none" frameborder="0"></iframe></p>
<p>The governments in the <a href="https://s3.documentcloud.org/documents/6801979/Honolulu-Climate-Lawsuit-3-9-2020.pdf">Honolulu case allege</a> that the oil companies “are directly responsible” for a substantial rise in carbon dioxide emissions that have been driving climate change. They say the companies should contribute their <a href="https://commonwealthmagazine.org/energy/fair-share-for-the-fossil-fuel-industry/">fair share</a> to defray some of the costs.</p>
<p>The gist of Honolulu’s complaint is that the big oil companies <a href="https://www.science.org/doi/10.1126/science.abk0063">have known for decades</a> that their products cause climate change, yet their public statements continued to <a href="https://theconversation.com/what-big-oil-knew-about-climate-change-in-its-own-words-170642">sow doubts</a> about <a href="https://theconversation.com/i-was-an-exxon-funded-climate-scientist-49855">what was known</a>, and they failed to warn their customers, investors and the public about the dangers posed by their products. </p>
<p>Were it not for this deception, the lawsuit says, the city and county would not be facing mounting costs of abating the damage from climate change.</p>
<p>Importantly, the complaint is based on state – not federal – law. It alleges that the defendants have violated established common law rules long recognized by the courts involving nuisance, failure to warn and trespass.</p>
<p>The city and county want the companies to help fund climate adaptation measures – everything from building seawalls and raising buildings to buying flood-prone properties and restoring beaches and dunes.</p>
<h2>Supreme Court could have killed these cases</h2>
<p>Not surprisingly, the oil companies have thrown their vast legal resources into fighting these cases.</p>
<p>On April 24, however, they lost one of their most powerful arguments.</p>
<p>The U.S. Supreme Court <a href="https://www.supremecourt.gov/orders/courtorders/042423zor_1p24.pdf">declined to hear challenges</a> in the Hawaii case and four others involving the seemingly technical question of which court should hear these cases: state or federal.</p>
<p>The oil companies had “<a href="https://www.bonalaw.com/insights/legal-resources/requirements-for-removing-a-case-from-state-court-to-federal-court">removed</a>” the cases from state court to federal court, <a href="http://climatecasechart.com/case/city-county-of-honolulu-v-sunoco-lp/">arguing that damage lawsuits</a> for climate change go beyond the limits of state law and are governed by federal law. </p>
<p>That theory would have derailed all five cases – because there is no federal common law for greenhouse gases.</p>
<p>The court made that position clear in 2011 in <a href="https://www.oyez.org/cases/2010/10-174">American Electric Power Co. v. Connecticut</a>. Several state and local governments had sued five major power companies for violating the federal common law of interstate nuisance and asked for a court order forcing these companies to reduce their emissions. The Supreme Court refused, holding that the federal Clean Air Act displaced federal common law for these gases. </p>
<p>In <a href="https://law.justia.com/cases/federal/appellate-courts/ca9/09-17490/09-17490-2012-09-21.html">Native Village of Kivalina v. Exxon Mobil Corp.</a>, a federal court of appeals extended that holding to also bar claims for monetary damages based on federal common law.</p>
<figure class="align-center ">
<img alt="Sandbags sit outside a home near a beach in Oahu, Hawaii, where waves have eaten into the shoreline almost up to the house." src="https://images.theconversation.com/files/527383/original/file-20230521-128284-x96kaz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/527383/original/file-20230521-128284-x96kaz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/527383/original/file-20230521-128284-x96kaz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/527383/original/file-20230521-128284-x96kaz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/527383/original/file-20230521-128284-x96kaz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/527383/original/file-20230521-128284-x96kaz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/527383/original/file-20230521-128284-x96kaz.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">Several coastal communities, including in Honolulu County, facing increasing erosion want oil companies to help pay for protective infrastructure.</span>
<span class="attribution"><a class="source" href="https://newsroom.ap.org/detail/4c2fc5b90f894fe7963daeb19724bce4?ext=true">AP Photo/Audrey McAvoy</a></span>
</figcaption>
</figure>
<p>To avoid this fate, Honolulu and the other plaintiffs focused on violations of state law, not federal law. Without exception, the federal courts of appeals sided with them and sent the cases back to state court.</p>
<h2>What happens next?</h2>
<p>The Honolulu case leads the pack at this point.</p>
<p>In 2022, the 1st Circuit Court in Hawaii <a href="http://climatecasechart.com/climate-change-litigation/wp-content/uploads/sites/16/case-documents/2022/20220203_docket-1CCV-20-0000380_ruling.pdf">denied the oil companies’ motion</a> to dismiss the case based on the argument that the Clean Air Act also preempts state common law. This could open the door for discovery to begin sometime this year.</p>
<p>In discovery, senior corporate officers – perhaps including <a href="https://theconversation.com/exxons-rex-tillerson-and-the-rise-of-big-oil-in-american-politics-70260">former Exxon Mobil CEO Rex Tillerson</a>, who was secretary of state under Donald Trump – will be required to answer questions under oath about what the companies knew about climate change versus what they disclosed to the public.</p>
<figure class="align-center ">
<img alt="Rex Tillerson, a smiling older man in a suit and tie, walks out of a courthouse with security guards." src="https://images.theconversation.com/files/527353/original/file-20230521-106641-dkrcqe.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/527353/original/file-20230521-106641-dkrcqe.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/527353/original/file-20230521-106641-dkrcqe.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/527353/original/file-20230521-106641-dkrcqe.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/527353/original/file-20230521-106641-dkrcqe.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/527353/original/file-20230521-106641-dkrcqe.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/527353/original/file-20230521-106641-dkrcqe.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">In 2019, former Exxon Mobil CEO Rex Tillerson testified in a securities fraud lawsuit brought by the New York attorney general’s office. The judge ruled in Exxon’s favor.</span>
<span class="attribution"><a class="source" href="https://newsroom.ap.org/detail/ExxonClimateLawsuit/cc7e743167614cb4bf7a4ec99319422f/photo">AP Photo/Seth Wenig</a></span>
</figcaption>
</figure>
<p>Evidence <a href="https://www.science.org/doi/10.1126/science.abk0063">from Exxon documents</a>, described in a recent study by science historians Naomi Oreskes and Geoffrey Supran, shows that the company’s own scientists “knew as much as academic and government scientists knew” about climate change going back decades. But instead of communicating what they knew, “Exxon worked to deny it,” Supran and Oreskes write. The company overemphasized uncertainties and cast doubt on climate models.</p>
<p>This is the kind of evidence that could sway a jury. The standard of proof in a civil case like Honolulu’s is “preponderance of the evidence,” which roughly translates to 51%. Ten of the 12 jurors must agree on a verdict.</p>
<p>Any verdict likely would be appealed, perhaps all the way to the U.S. Supreme Court, and it could be years before the Honolulu case is resolved.</p>
<h2>Lawsuits don’t begin to cover the damage</h2>
<p>It is unlikely that even substantial verdicts in these cases will come close to covering the full costs of damage from climate change.</p>
<p>According to the National Oceanic and Atmospheric Administration, <a href="https://www.climate.gov/news-features/blogs/2022-us-billion-dollar-weather-and-climate-disasters-historical-context">in 2022 alone the U.S. sustained</a> 18 weather and climate disasters that each exceeded $1 billion in damage. Together, they cost over $165 billion.</p>
<p>But for many of the communities most at risk from these disasters, every penny counts. We believe establishing the oil companies’ responsibility may also discourage further investments in fossil fuel production by banks and brokerage houses already nervous about the <a href="https://www.ey.com/en_it/banking-capital-markets-risk-regulatory-transformation/climate-change-and-risk-three-key-challenges-facing-banks">financial risks</a> of climate disruption.</p><img src="https://counter.theconversation.com/content/205009/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Honolulu, Baltimore, Charleston, S.C. and several other cities harmed by rising seas and extreme weather are suing the oil industry. At stake is who pays for the staggering costs of climate change.Patrick Parenteau, Professor of Law Emeritus, Vermont Law & Graduate SchoolJohn Dernbach, Professor of Law, Widener UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2055632023-05-18T03:05:52Z2023-05-18T03:05:52ZFear and Wonder podcast: how climate action can create a more liveable future for all<p>Should poorer countries be compensated for climate disasters that aren’t their own making?</p>
<p>The concept of “loss and damage” was one of the most contentious raised at the United Nations COP27 climate summit in Egypt in November 2022. After difficult diplomatic discussions, it was agreed that a loss and damage fund should be established to compensate countries that are most vulnerable to the impacts of climate change. It’s a major step forward, but exactly how it will work remains to be seen.</p>
<p>In our final episode of Fear & Wonder, we discuss the Intergovernmental Panel on Climate Change’s (IPCC) final <a href="https://www.ipcc.ch/report/ar6/syr/">Synthesis Report</a> and how its scientific findings influence global climate policy negotiations. We explore how the lived experience of climate change is already affecting human health in West Africa.</p>
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<p><iframe id="tc-infographic-822" class="tc-infographic" height="100" src="https://cdn.theconversation.com/infographics/822/cfe1cb0d01c023aeef001dac6a65f27fcee4c0bb/site/index.html" width="100%" style="border: none" frameborder="0"></iframe></p>
<p>We meet Senegalese meteorologist and IPCC author Aïda Diongue-Niang, who explains how African nations are already highly vulnerable to the impacts of climate change. We follow her real-time updates from COP27 and the gruelling final approval session of the Synthesis Report. Her behind-the-scenes account reveals the dedication and determination of scientists involved in the IPCC process.</p>
<p>We hear from Mauritanian public health expert and IPCC author Guéladio Cissé, who details how more intense rainfall is already increasing the risk of water-borne and vector-borne diseases. So why is only a tiny fraction of climate adaptation funding devoted to health, and what needs to change?</p>
<p>Finally, we recap what we’ve learned throughout this podcast. We reflect on how the event that sparked its creation – the Australian Black Summer bushfires of 2019–20 – has inspired survivors to fight for climate action.</p>
<p>To listen and subscribe, click <a href="https://shows.acast.com/fear-and-wonder-stories-from-un-climate-experts">here</a>, or click the icon for your favourite podcast app in the graphic above.</p>
<hr>
<p><em>Fear and Wonder is sponsored by the <a href="https://www.climatecouncil.org.au/">Climate Council</a>, an independent, evidence-based organisation working on climate science, impacts and solutions.</em></p><img src="https://counter.theconversation.com/content/205563/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Dr Joelle Gergis has received funding from the Australian Research Council and the Australian Government's Department of Industry, Science, Energy and Resources in the past. She currently receives funding from the Australian National University.</span></em></p><p class="fine-print"><em><span>Michael Green 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>Fear and Wonder is a new climate podcast, brought to you by The Conversation and the Climate Council. In this final episode, we discuss how poorer nations are at greater risk to a changing climate.Joelle Gergis, Senior Lecturer in Climate Science, Australian National UniversityMichael Green, Host + Producer, The ConversationLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2055082023-05-12T14:58:40Z2023-05-12T14:58:40ZClimate change first ‘went viral’ exactly 70 years ago<p>We have grown so used to many things. To the pictures of wildfires and cremated animals, to the ice sheets calving into the ocean, to the promises of world leaders that they will heed the “last chance” warning of the scientists. </p>
<p>It’s hard for anyone under the age of 40 to remember a time when carbon dioxide build-up, whether it was “the greenhouse effect”, or “global warming” or “climate change” or now “climate crisis”, wasn’t in the news. </p>
<p>The long hot summer of 1988 – 35 years ago – is held as the moment that world leaders began to mouth the right pieties. </p>
<p>Presidential candidate (and soon to be president) George H.W. Bush said he would use the “White House effect” to fix the Greenhouse Effect (<a href="https://theconversation.com/george-bush-sr-could-have-got-in-on-the-ground-floor-of-climate-action-history-would-have-thanked-him-108050">he didn’t</a>). UK prime minister Margaret Thatcher warned of a <a href="https://www.independent.co.uk/news/uk/margaret-thatcher-coal-mines-boris-johnson-b1899098.html">giant experiment</a> being conducted “with the system of this planet itself”.</p>
<p>Thirty-five years. But it was actually 35 years before that – fully 70 years ago this month – that the danger of carbon dioxide build-up in the atmosphere first travelled around the world.</p>
<p>That carbon dioxide trapped heat was uncontroversial. Irish scientist <a href="https://theconversation.com/john-tyndall-the-forgotten-co-founder-of-climate-science-143499">John Tyndall</a> (possibly drawing on the work of an American, <a href="https://theconversation.com/scientists-understood-physics-of-climate-change-in-the-1800s-thanks-to-a-woman-named-eunice-foote-164687">Eunice Foote</a>) had shown that it did back in the mid-1800s. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/525892/original/file-20230512-23-ymzyoq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Portrait of man" src="https://images.theconversation.com/files/525892/original/file-20230512-23-ymzyoq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/525892/original/file-20230512-23-ymzyoq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=802&fit=crop&dpr=1 600w, https://images.theconversation.com/files/525892/original/file-20230512-23-ymzyoq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=802&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/525892/original/file-20230512-23-ymzyoq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=802&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/525892/original/file-20230512-23-ymzyoq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1008&fit=crop&dpr=1 754w, https://images.theconversation.com/files/525892/original/file-20230512-23-ymzyoq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1008&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/525892/original/file-20230512-23-ymzyoq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1008&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Tyndall conducted an experiment to demonstrate the greenhouse effect.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/67474303@N06/12454907405/">Royal Institution</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-sa/4.0/">CC BY-NC-SA</a></span>
</figcaption>
</figure>
<p>In 1895, Swedish Nobel prize winner Svante Arrhenius had suggested that – over hundreds of years – the build-up of carbon dioxide released when humans burn oil, coal and gas might trap so much heat as to melt the tundra and make freezing winters a thing of the past. </p>
<p>His work was challenged, but the idea occasionally popped up in popular journals. In 1938 English steam engineer Guy Callendar suggested to the Royal Meteorological Society in London that warming was underway.</p>
<p>But it was in early May, 1953, at a meeting of the American Geophysical Union, that Canadian physicist Gilbert Plass – who had been corresponding with Callendar – told the gathered scientists that trouble was afoot.</p>
<p>Plass said that:</p>
<blockquote>
<p>The large increase in industrial activity during the present century is discharging so much carbon dioxide into the atmosphere that the average temperature is rising at the rate of 1.5 degrees per century.</p>
</blockquote>
<p>This got picked up by the Associated Press and other wire services and appeared in <a href="https://www.nytimes.com/1953/05/24/archives/how-industry-may-change-climate.html">newspapers</a> all around the world (even as far afield as the Sydney Morning Herald). Plass’s warning also popped up in <a href="https://archive.org/details/sim_newsweek-us_1953-05-18_41_20/page/74/mode/2up?view=theater">Newsweek</a> on May 18 and in <a href="https://allouryesterdays.info/2022/05/25/may-25-1953-i-read-about-them-in-time-magazine-gilbert-plasss-greenhouse-warning/">Time</a> on May 25.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/525931/original/file-20230512-19-6rc5me.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="photo of man in 1950s" src="https://images.theconversation.com/files/525931/original/file-20230512-19-6rc5me.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/525931/original/file-20230512-19-6rc5me.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=864&fit=crop&dpr=1 600w, https://images.theconversation.com/files/525931/original/file-20230512-19-6rc5me.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=864&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/525931/original/file-20230512-19-6rc5me.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=864&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/525931/original/file-20230512-19-6rc5me.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1086&fit=crop&dpr=1 754w, https://images.theconversation.com/files/525931/original/file-20230512-19-6rc5me.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1086&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/525931/original/file-20230512-19-6rc5me.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1086&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Gilbert Plass in 1955.</span>
<span class="attribution"><span class="source">Hodges Photographers, courtesy of AIP Emilio Segrè Visual Archives</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>The fact that the world was warming was already uncontroversial among scientists. But the emphatic connection with carbon dioxide made by Plass, as opposed to competing theories such as orbital wobbles or sunspot activity, was newsworthy.</p>
<p>Plass had become interested in the question of carbon dioxide buildup while working for the Ford Motor Company. He looked at how carbon dioxide actually functions in the real world, not just at sea level (without getting too technical. Many scientists had dismissed Arrhenius’s earlier work on the basis of false confidence that carbon dioxide worked the same there as in the stratosphere).</p>
<p>Plass kept working on the issue, with technical and popular publications through the rest of the 1950s. In 1956, he had an academic article on “<a href="https://nsdl.library.cornell.edu/websites/wiki/index.php/PALE_ClassicArticles/archives/classic_articles/issue1_global_warming/n7._Plass__1956corrected.pdf">the carbon dioxide theory of climate change</a>” published in the Swedish scientific journal Tellus, and also a popular article in the <a href="https://www.jstor.org/stable/27826805">American Scientist</a>. And he was present at the <a href="https://allouryesterdays.info/2023/03/11/march-12-1963-first-ever-carbon-dioxide-build-up-conference/">first major meetings</a> to discuss carbon dioxide build up. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/525868/original/file-20230512-21-udbd4r.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Newspaper article" src="https://images.theconversation.com/files/525868/original/file-20230512-21-udbd4r.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/525868/original/file-20230512-21-udbd4r.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=715&fit=crop&dpr=1 600w, https://images.theconversation.com/files/525868/original/file-20230512-21-udbd4r.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=715&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/525868/original/file-20230512-21-udbd4r.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=715&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/525868/original/file-20230512-21-udbd4r.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=898&fit=crop&dpr=1 754w, https://images.theconversation.com/files/525868/original/file-20230512-21-udbd4r.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=898&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/525868/original/file-20230512-21-udbd4r.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=898&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 Irish Times discusses climate change, way back in 1954.</span>
<span class="attribution"><a class="source" href="https://allouryesterdays.info/2023/04/22/april-23-1954-irish-times-runs-carbon-dioxide-climate-story-yes-1954/">Irish Times / allouryesterdays.info</a></span>
</figcaption>
</figure>
<p>Meanwhile, the carbon dioxide theory started getting more coverage among science journalists. One, George Wendt, wrote up the findings in the then well-regarded UNESCO Courier, and this got excerpted in the <a href="https://allouryesterdays.info/2023/04/22/april-23-1954-irish-times-runs-carbon-dioxide-climate-story-yes-1954/">Irish Times in 1954</a>, the same year that British journalists started mentioning it. </p>
<p>In 1957 the then-new magazine New Scientist mentioned it. By the end of the 1950s, anyone who read a newspaper could have been aware of the basic idea.</p>
<p>Throughout the 50s and 60s US, Swedish, German and Soviet scientists were examining the issue. In 1965 President Lyndon Johnson even namechecked carbon dioxide build-up in an <a href="https://www.presidency.ucsb.edu/documents/special-message-the-congress-conservation-and-restoration-natural-beauty">address to Congress</a>. </p>
<p>By the end of the 1960s international collaboration was beginning, though there was caution still. For instance, in April 1969 the American scientist Charles Keeling, who had been measuring atmospheric carbon dioxide concentrations at a Hawaiian observatory, revealed that he had been <a href="https://allouryesterdays.info/2023/04/24/april-25-1969-keeling-says-pressured-not-to-talk-bluntly-about-what-is-to-be-done/">asked to change the title</a> of a lecture from, “If carbon dioxide from fossil fuels is changing man’s environment, what will we do about it?” to “Is carbon dioxide from fossil fuel changing man’s environment?”</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/525884/original/file-20230512-19-xbr958.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Magazine article headline and standfirst" src="https://images.theconversation.com/files/525884/original/file-20230512-19-xbr958.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/525884/original/file-20230512-19-xbr958.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=308&fit=crop&dpr=1 600w, https://images.theconversation.com/files/525884/original/file-20230512-19-xbr958.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=308&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/525884/original/file-20230512-19-xbr958.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=308&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/525884/original/file-20230512-19-xbr958.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=387&fit=crop&dpr=1 754w, https://images.theconversation.com/files/525884/original/file-20230512-19-xbr958.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=387&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/525884/original/file-20230512-19-xbr958.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">Plass promoted his theory in Scientific American magazine in 1959.</span>
<span class="attribution"><a class="source" href="https://www.jstor.org/stable/24940327?searchText=&searchUri=&ab_segments=&searchKey=&refreqid=fastly-default%3Aecec3999465e38b288b52107d7670435">Scientific American (1959)</a></span>
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<p>For climate historians like me, the 1970s are a fascinating period of intense measurement, modelling, observation and thinking which, by the end of the decade, produced a working consensus that there was serious trouble ahead. In effect, Plass had nailed it.</p>
<p>When Plass spoke out, the atmospheric concentration of carbon dioxide was at about 310 parts per million. Today, they’re 423 or so. Every year, as we burn more oil, coal and gas, the concentration climbs and more heat is trapped.</p>
<p>By the time Plass’s warning is 100 years old, the concentrations will be much higher. There’s a very good chance we will have gone over the 2°C warming level that used to be regarded as “safe”.</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><em>This story was updated on May 15 2023. In 1938 Callendar presented his work to the Royal Meteorological Society, not the Royal Society as originally stated.</em></p><img src="https://counter.theconversation.com/content/205508/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Marc Hudson runs a website called All Our Yesterdays, allouryesterdays.info, with daily blog posts about events that happened 'on this day', around climate science, politics, technology and protest. </span></em></p>In May 1953, scientist Gilbert Plass made some extraordinarily prescient comments.Marc Hudson, Visiting Fellow, SPRU, University of Sussex Business School, University of SussexLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2052922023-05-10T20:01:28Z2023-05-10T20:01:28ZSmoke from the Black Summer fires could have made the triple La Niña more likely<p>The 2019-2020 bushfire season was devastating. Vast areas of pristine forest burned, many for the first time in memory. By some estimates, a billion native animals died up and down Australia’s east coast. Dozens of people died. </p>
<p>While Sydney’s skies are blue again, Australia’s Black Summer has kept scientists around the globe busy. The sheer size of these megafires produced startling effects. Recently, researchers found the huge volumes of smoke <a href="https://www.abc.net.au/news/2023-03-10/how-the-black-summer-bushfires-depleted-the-ozone-layer/102076136">ate away</a> at our protective ozone layer. </p>
<p>Now, <a href="https://dx.doi.org/10.1126/sciadv.adg1213">new research</a> by American scientists suggests the Black Summer fires were massive enough to influence the <a href="https://cosmosmagazine.com/earth/enso-iod-weather-patterns-explainer/#:%7E:text=El%20Ni%C3%B1o%20and%20La%20Ni%C3%B1a%2C%20also%20called%20El%20Ni%C3%B1o%20Southern,to%20the%20north%20of%20Australia.">El Niño Southern Oscillation cycle</a>. It’s one of the most important drivers of unusual weather over the entire globe – and one which Australians know intimately.</p>
<p>The <a href="https://theconversation.com/la-nina-is-finishing-an-extremely-unusual-three-year-cycle-heres-how-it-affected-weather-around-the-world-196561">three successive years</a> of La Niña we just had? They could have been made more likely by the Black Summer fires. The reason, strangely enough, is the smoke. </p>
<p>But it’s important not to say the link is proven. While groundbreaking, this research relies on a single model. It’s too early to clearly say bushfire smoke can trigger La Niña. </p>
<h2>Where there’s fire, there’s smoke</h2>
<p>We’ve long known that the huge volume of ash blown high into the upper atmosphere by a big volcanic eruption can cool Earth’s surface for many months, or <a href="https://www.ipcc.ch/report/sixth-assessment-report-working-group-i/">even years</a>. </p>
<p>We also know volcanoes <a href="https://doi.org/10.1007/s41748-022-00331-z">can influence</a> the tropical Pacific, and thus affect whether an El Niño or a La Niña phase develops. </p>
<p>How? By blocking light. Particles of ash reduce how much light gets to the surface. </p>
<p>Volcanic ash gets blown high into the stratosphere, the part of the atmosphere just above the clouds where long-haul airplanes fly. Then, sunlight gets reflected before it reaches the ground, thus cooling the surface much like an umbrella can. </p>
<h2>Is bushfire smoke the same as volcanic ash?</h2>
<p>It’s tempting to equate smoke with ash, and assume a large enough bushfire would have similar effects to a volcano. </p>
<p>But there are important differences. Most obviously, a bushfire does not smell of rotten eggs.</p>
<p>That might sound unimportant, but the rotten egg smell – which comes from sulfur – indicates major differences in the composition of volcanic ash and bushfire smoke. </p>
<p>Different chemicals could mean very different responses to sunlight once in the atmosphere, which in turn could affect how much light is reflected. </p>
<p>Second, bushfires don’t explode.</p>
<p>A decent volcano erupts with enough force to blast smoke high into the stratosphere. Bushfires don’t have the same propulsive force.</p>
<p>Bushfire smoke is hot, though, and hot smoke rises well. Some of the smoke from the Black Summer fires <a href="https://www.science.org/doi/abs/10.1126/science.abe1415">reached the stratosphere</a>, although after a much longer interval than for volcanic eruptions. </p>
<p>So, does a large bushfire have the same effect on climate as a volcano?</p>
<p>The American researchers begin by checking the similarities using climate model simulations. They found bushfire smoke does indeed shade the surface from sunlight in these simulations. </p>
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Read more:
<a href="https://theconversation.com/australias-black-summer-of-fire-was-not-normal-and-we-can-prove-it-172506">Australia's Black Summer of fire was not normal – and we can prove it</a>
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<p>How much? Over a region of the south-eastern Pacific, about 150 terawatts of sunlight bounced back to space – the equivalent of about 100,000 coal power plants. </p>
<h2>Clouds matter</h2>
<p>The surprising finding is how it happens. In contrast to eruptions, bushfire smoke didn’t reflect the sunlight directly. Instead, clouds were responsible. </p>
<p>How does that work? This is where the magic of the climate system kicks in. Our atmosphere, oceans and lands are constantly interacting with each other.</p>
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<a href="https://images.theconversation.com/files/525315/original/file-20230510-17-634wtl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Clouds over ocean" src="https://images.theconversation.com/files/525315/original/file-20230510-17-634wtl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/525315/original/file-20230510-17-634wtl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/525315/original/file-20230510-17-634wtl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/525315/original/file-20230510-17-634wtl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/525315/original/file-20230510-17-634wtl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=504&fit=crop&dpr=1 754w, https://images.theconversation.com/files/525315/original/file-20230510-17-634wtl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=504&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/525315/original/file-20230510-17-634wtl.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"></a>
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<span class="caption">Whiter, thicker clouds make the surface of the ocean cooler.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
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<p>In their simulations, Black Summer smoke was first blown eastward by strong winds in the atmosphere. Under specific conditions, some smoke particles can interact with droplets in clouds and make clouds thicker and brighter. One region where this can happen is the subtropical south-eastern Pacific. </p>
<p>The researchers were able to show the brightness of the clouds over this area increased considerably just around the time when the smoke particles arrived. </p>
<p>These brighter, whiter clouds reflected more sunlight back into space and shaded the surface underneath. The net effect: cooler seawater. </p>
<p>The effect was particularly important because of the timing. Smoke-whitened clouds emerged around our summer solstice in late December, which is the same time of year when the strength of the incoming sunlight peaks in the southern hemisphere.</p>
<p>How is this linked to La Niña? </p>
<p>Follow the chain: huge volumes of smoke blow east where they whiten clouds, cool the seawater, and cause less water to evaporate.</p>
<p>Surface winds carried this cooler, drier air over the tropical Pacific, where it cooled the ocean surface again, and made it harder for tropical storms to form.</p>
<p>A cooler sea surface in the tropical Pacific is a hallmark of La Niña, the cold phase of the El Niño Southern Oscillation cycle. </p>
<p>That’s how this research was able to trace a link between Black Summer smoke and the rare back-to-back La Niña events in 2019-20 and 2020-21. As you know, we ended up having an even rarer triple La Niña in 2021-22, though the research period ends before this. </p>
<h2>Is the link now proven? Not quite</h2>
<p>This study offers a consistent physical explanation for how bushfires might influence the El Niño cycle. </p>
<p>It’s yet another example of how complex climate science can be, and how much we can still be surprised and challenged by what mother nature presents us. </p>
<p>But there are a few caveats to keep in mind.</p>
<p>For one, the ENSO cycle in the simulation was heading for a double La Niña even without the impact of the smoke. The simulation stops in the winter of 2021, which is before the real-world ENSO tipped into a third La Niña. </p>
<p>What does that mean? In short, we can’t know for sure if the effect of the bushfire smoke really did cause the triple La Niña. </p>
<p>Another caveat is the fact the study relied on a single climate model, and relies heavily on the representation of clouds in that model.</p>
<p>That’s a potential problem, because we know clouds – and especially their interactions with aerosols like smoke – are still the largest source of uncertainties and model errors. </p>
<p>To prove or disprove the link, we’ll have to simulate the impact of ballooning Black Summer smoke plumes across many different models. </p>
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Read more:
<a href="https://theconversation.com/smoke-from-the-black-summer-fires-created-an-algal-bloom-bigger-than-australia-in-the-southern-ocean-164564">Smoke from the Black Summer fires created an algal bloom bigger than Australia in the Southern Ocean</a>
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<img src="https://counter.theconversation.com/content/205292/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Martin Jucker 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>Where there’s fire, there’s smoke – could plumes from the Black Summer of fire have cooled regions of the Pacific and triggered a La Niña? New research suggests it’s possible.Martin Jucker, Lecturer in Atmospheric Dynamics, UNSW SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2051142023-05-10T20:01:22Z2023-05-10T20:01:22ZFear and Wonder podcast: the solutions needed to address climate change already exist<p>One of the key findings of the Intergovernmental Panel on Climate Change’s (IPCC) <a href="https://www.ipcc.ch/report/ar6/syr/">Synthesis Report</a> is that there are solutions available right now, across all sectors of the economy, that could at least halve greenhouse gas emissions by 2030.</p>
<p>“The problem is getting worse,” explains Greg Nemet, a Canadian renewable policy expert and IPCC author. “But we’ve got solutions now that are so much more affordable than they were.”</p>
<p>After studying advances in solar technology, which has seen rapid expansion and price reductions, he’s optimistic about our capacity to avert the worst possible climate outcomes. </p>
<p>In this week’s episode of our climate podcast Fear and Wonder, we speak to Greg about the pace of change in the solar industry and whether it can be replicated for other technologies.</p>
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Read more:
<a href="https://theconversation.com/introducing-fear-and-wonder-the-conversations-new-climate-podcast-200066">Introducing Fear and Wonder: The Conversation's new climate podcast</a>
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<p>We also hear from fellow IPCC author and Algerian energy policy expert Yamina Saheb, about the emission reductions that are possible by adopting age-old sustainability concepts. She explains the idea of “sufficiency”, which aims to reduce the overall demand for energy, materials, land and water, while still delivering human wellbeing for all.</p>
<p>Finally, we ask Greg and Yamina about carbon dioxide removal, one of the most controversial technologies assessed by the IPCC. Is it the silver bullet solution we’ve all been waiting for, or should we be supporting the policy and technology options that are here with us now?</p>
<p>To listen and subscribe, click <a href="https://shows.acast.com/fear-and-wonder-stories-from-un-climate-experts">here</a>, or click the icon for your favourite podcast app in the graphic above.</p>
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<p><em>Fear and Wonder is sponsored by the <a href="https://www.climatecouncil.org.au/">Climate Council</a>, an independent, evidence-based organisation working on climate science, impacts and solutions.</em></p><img src="https://counter.theconversation.com/content/205114/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Dr Joelle Gergis has received funding from the Australian Research Council and the Australian Government's Department of Industry, Science, Energy and Resources in the past. She currently receives funding from the Australian National University.</span></em></p><p class="fine-print"><em><span>Michael Green 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>Fear and Wonder is a new climate podcast, brought to you by The Conversation, and sponsored by the Climate Council. In this episode, we discuss possible solutions to the climate crisis.Joelle Gergis, Senior Lecturer in Climate Science, Australian National UniversityMichael Green, Host + Producer, The ConversationLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2049752023-05-04T14:25:46Z2023-05-04T14:25:46ZCloud seeding can increase rain and snow, and new techniques may make it a lot more effective – podcast<figure><img src="https://images.theconversation.com/files/524204/original/file-20230503-19-bx8o26.jpg?ixlib=rb-1.1.0&rect=418%2C594%2C6930%2C4308&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Cloud seeding can increase rainfall and reduce hail damage to crops, but its use is limited.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/colorado-supercell-royalty-free-image/1303884216?phrase=Rain+storm&adppopup=true">John Finney Photography/Moment via Getty Images</a></span></figcaption></figure><p>When an unexpected rainstorm leaves you soaking wet, it is an annoyance. When a drought leads to fires, crop failures and water shortages, the significance of weather becomes vitally important.</p>
<p>If you could control the weather, would you?</p>
<p>Small amounts of rain can mean the difference between struggle and success. For <a href="https://climateviewer.com/2014/03/25/history-cloud-seeding-pluviculture-hurricane-hacking/">nearly 80 years</a>, an approach called cloud seeding has, in theory, given people the ability to get more rain and snow from storms and make hailstorms less severe. But only recently have scientists been able to peer into clouds and begin to understand how effective cloud seeding really is.</p>
<p>In this episode of “The Conversation Weekly,” we speak with three researchers about the simple yet murky science of cloud seeding, the economic effects it can have on agriculture, and research that may allow governments to use cloud seeding in more places.</p>
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<p><a href="https://scholar.google.com/citations?user=BSQl42wAAAAJ&hl=en&oi=ao">Katja Friedrich</a>, a professor of atmospheric and oceanic sciences at the University of Colorado, Boulder in the U.S., is a leading researcher on cloud seeding. “When we do cloud seeding, we are looking for clouds that have tiny super-cooled liquid droplets,” she explains. Silver iodide is very similar in structure to an ice crystal. When the droplets touch a particle of silver iodide, “they freeze, then they can start merging with other ice crystals, become snowflakes and fall out of the cloud.”</p>
<p>While the process is fairly straightforward, measuring how effective it is in the real world is not, according to Friedrich. “The problem is that once we modify a cloud, it’s really difficult to say what would’ve happened if you hadn’t cloud-seeded.” It’s hard enough to predict weather without messing with it artificially. </p>
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<a href="https://images.theconversation.com/files/524222/original/file-20230503-1294-7b7p2j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A plane wing with a cylindrical device attached." src="https://images.theconversation.com/files/524222/original/file-20230503-1294-7b7p2j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/524222/original/file-20230503-1294-7b7p2j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=370&fit=crop&dpr=1 600w, https://images.theconversation.com/files/524222/original/file-20230503-1294-7b7p2j.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=370&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/524222/original/file-20230503-1294-7b7p2j.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=370&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/524222/original/file-20230503-1294-7b7p2j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=465&fit=crop&dpr=1 754w, https://images.theconversation.com/files/524222/original/file-20230503-1294-7b7p2j.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=465&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/524222/original/file-20230503-1294-7b7p2j.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=465&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">Cloud seeding is usually done by planes equipped with devices – like the one attached to the wing of this plane – that spray silver iodide into the atmosphere.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Cloud_seeding#/media/File:Hagelflieger-EDTD.jpg">Zuckerle/Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
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<p>In 2017, Friedrich’s research group had a breakthrough in measuring the effect of cloud seeding. “We flew some aircraft, released silver iodide and generated these clouds that were like these six exact lines that were downstream of where the aircraft were seeding,” she says. They then had a second aircraft fly through the clouds. “We could actually <a href="https://doi.org/10.1073/pnas.1716995115">quantify how much snow we could produce</a> by two hours of cloud seeding.” That effect, according to research on cloud seeding, is an increase in precipitation of somewhere around 5% to 20% or 30%, depending on conditions.</p>
<p>Measuring the effect on precipitation – whether rain or snow – directly may have taken complex science and a bit of luck, but in places that have been using cloud seeding for long periods of time, the economic benefits are shockingly clear. </p>
<p><a href="https://www.ndsu.edu/agriculture/ag-home/directory/dean-bangsund">Dean Bangsund</a> is a researcher at North Dakota State University who studies the economics of agriculture. “We have a high amount of hail damage in North Dakota,” said Bangsund. For decades, the state government has been using cloud seeding to reduce hail damage, as cloud seeding leads to the formation of more pieces of smaller hail compared to fewer pieces of larger hail. “It doesn’t 100% eliminate hail; it’s designed to soften the impact.”</p>
<p>Every 10 years, the state of North Dakota does an <a href="https://www.cabdirect.org/cabdirect/abstract/20193399635">analysis on the economic impacts of the cloud seeding</a> program, measuring both reduction in hail damage and benefits from increased rain. Bangsund led the last report and says that for every dollar spent on the cloud seeding program, “we are looking at something that is anywhere from $8 or $9 in benefit on the really lowest scale, up to probably $20 of impact per acre.” With millions of acres of agricultural fields in the cloud seeding area, that is a massive economic benefit.</p>
<p>Both Freidrich and Bangsund emphasized that cloud seeding, while effective in some cases, cannot be used everywhere. There is also a lot of uncertainty in how much of an effect it has. One way to improve the effectiveness and applicability of cloud seeding is by improving the seed. <a href="https://scholar.google.com/citations?view_op=list_works&hl=en&hl=en&user=OxrNpiEAAAAJ&sortby=pubdate">Linda Zou</a> is a professor of civil infrastructure and environmental engineering at Khalifa University in the United Arab Emirates. </p>
<p>Her work has focused on developing a replacement for silver iodide, and her lab has <a href="https://www.technologyreview.com/2022/03/28/1048275/scientists-advance-cloud-seeding-capabilities-with-nanotechnology/">developed what she calls a nanopowder</a>. “I start with table salt, which is sodium chloride,” says Zou. “This desirable-sized crystal is then coated with a thin nanomaterial layer of titanium dioxide.” When salt gets wet, it melts and forms a droplet that can efficiently merge with other droplets and fall from a cloud. Titanium dioxide attracts water. Put the two together and you get a very effective cloud-seeding material. </p>
<p>From indoor experiments, Zou found that “with the nanopowders, there are 2.9 times the formation of larger-size water droplets.” These nanopowders can also form ice crystals at warmer temperatures and less humidity than silver iodide. </p>
<p>As Zou says, “if the material you are releasing is more reactive and can work in a much wider range of conditions, that means no matter when you decide to use it, the chance of success will be greater.”</p>
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<p>This episode was written and produced by Katie Flood. Mend Mariwany is the executive producer of The Conversation Weekly. Eloise Stevens does our sound design, and our theme music is by Neeta Sarl.</p>
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<p class="fine-print"><em><span>None of the interviewees 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><p class="fine-print"><em><span> </span></em></p>Cloud seeding – spraying materials into clouds to increase precipitation – has been around for nearly 80 years. But only recently have scientists been able to measure how effective it really is.Daniel Merino, Associate Science Editor & Co-Host of The Conversation Weekly Podcast, The ConversationNehal El-Hadi, Science + Technology Editor & Co-Host of The Conversation Weekly Podcast, The ConversationLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2049082023-05-03T20:18:05Z2023-05-03T20:18:05ZFear and Wonder podcast: where to next on climate change? – Live bonus episode<figure><img src="https://images.theconversation.com/files/523964/original/file-20230503-22-lzc9tw.png?ixlib=rb-1.1.0&rect=2%2C0%2C1794%2C900&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption"></span> </figcaption></figure><p>“I’m often asked if I feel hopeful for the future,” says Lesley Hughes, climate scientist and former Intergovernmental Panel on Climate Change (IPCC) author.</p>
<p>“For me, hope is a strategy, rather than an emotion. Because if we don’t have hope and optimism, then we all give up, and if we all give up, then we are truly lost.”</p>
<p>In this live bonus episode of Fear & Wonder, The Conversation’s climate podcast, recorded on May 1, host Michael Green spoke with Hughes, alongside current IPCC authors Mark Howden and Frank Jotzo.</p>
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<p>All three guests have been at the forefront of climate science in Australia for decades. They trace how climate science went from a relatively peripheral topic to one of central importance to scientists and governments around the world.</p>
<p>They reflect on their respective journeys, the key takeaways from the IPCC’s most recent Synthesis Report, and the imminent challenges and opportunities for Australia and the world.</p>
<p>To listen and subscribe, click <a href="https://shows.acast.com/fear-and-wonder-stories-from-un-climate-experts">here</a>, or click the icon for your favourite podcast app in the graphic above.</p>
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<p><em>Fear and Wonder is sponsored by the <a href="https://www.climatecouncil.org.au/">Climate Council</a>, an independent, evidence-based organisation working on climate science, impacts and solutions.</em></p><img src="https://counter.theconversation.com/content/204908/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Michael Green 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>Fear and Wonder is a new climate podcast, brought to you by The Conversation, and sponsored by the Climate Council. In this live bonus episode, we discuss where to next on climate change.Michael Green, Host + Producer, The ConversationLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2046072023-05-02T12:13:12Z2023-05-02T12:13:12ZThe thinking error that makes people susceptible to climate change denial<figure><img src="https://images.theconversation.com/files/523279/original/file-20230427-24-j9qvgl.jpg?ixlib=rb-1.1.0&rect=422%2C15%2C4418%2C2783&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Expecting black-and-white answers can make it hard to see the truth.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/illustration/gears-in-the-mind-royalty-free-illustration/892833704">bubaone via Getty Images</a></span></figcaption></figure><p>Cold spells often bring climate change deniers out in force on social media, with hashtags like <a href="https://news.yahoo.com/nasa-yes-its-freezing-cold-no-that-doesnt-mean-climate-change-is-a-hoax-182933369.html">#ClimateHoax and #ClimateScam</a>. Former President Donald Trump often chimes in, <a href="https://www.washingtonpost.com/climate-environment/2019/01/29/trump-always-dismisses-climate-change-when-its-cold-not-so-fast-experts-say/">repeatedly claiming</a> that each cold snap disproves the existence of global warming.</p>
<p>From a scientific standpoint, these claims of disproof are absurd. Fluctuations in the weather don’t refute clear <a href="https://www.ncei.noaa.gov/access/monitoring/monthly-report/global/202301">long-term trends in the climate</a>. </p>
<p>Yet many people believe these claims, and the political result has been reduced willingness to take action to mitigate climate change.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/3E0a_60PMR8?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Sen. James Inhofe brought a snowball to the Senate floor in February 2015 to argue that because it was cold enough to snow in Washington, D.C., climate change wasn’t real. That year became the hottest on record and has since been surpassed.</span></figcaption>
</figure>
<p>Why are so many people susceptible to this type of disinformation? <a href="https://psychsciences.case.edu/people/other-faculty/">My field</a>, psychology, can help explain – and help people avoid being misled.</p>
<h2>The allure of black-and-white thinking</h2>
<p>Close examination of the arguments made by climate change deniers reveals the same mistake made over and over again. That mistake is the cognitive error known as black-and-white thinking, also called dichotomous and all-or-none thinking. As I explain in my book “<a href="https://www.amazon.com/Finding-Goldilocks-Creating-Personal-Relationships/dp/B08M8DS76S">Finding Goldilocks</a>,” black-and-white thinking is a source of dysfunction in mental health, relationships – and politics.</p>
<p>People are often susceptible to it because in many areas of life, dichotomous thinking does something helpful: It simplifies the world.</p>
<p>Binaries are easy to handle because there are only two possibilities to consider. When people face a spectrum of possibilities and nuance, they have to exert more mental effort. But when that spectrum is polarized into pairs of opposites, choices are clear and dramatic.</p>
<figure class="align-center ">
<img alt="Image of a person showing arrows pointing in opposite directions the person might take." src="https://images.theconversation.com/files/523335/original/file-20230427-30-ykiwpt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/523335/original/file-20230427-30-ykiwpt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/523335/original/file-20230427-30-ykiwpt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/523335/original/file-20230427-30-ykiwpt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/523335/original/file-20230427-30-ykiwpt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/523335/original/file-20230427-30-ykiwpt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/523335/original/file-20230427-30-ykiwpt.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">Most things don’t fall neatly into only two choices.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/standing-man-with-two-choices-royalty-free-image/155131774">eyetoeyePIX via Getty Images</a></span>
</figcaption>
</figure>
<p>This mental labor-saving device is practical in many everyday situations, but it is a poor tool for understanding complicated realities – and the climate is complicated.</p>
<p>Sometimes, people divide the spectrum in asymmetric ways, with one side much larger than the other. For example, perfectionists often categorize their work as either perfect or unsatisfactory, so even good and very good outcomes are <a href="https://www.guilford.com/books/Cognitive-Behavioral-Treatment-of-Perfectionism/Egan-Wade-Shafran-Antony/9781462527649/authors">lumped together with poor ones</a> in the unsatisfactory category. In dichotomous thinking like this, a single exception can tip a person’s view to one side. It’s like a pass/fail grading system in which 100% earns a pass and everything else gets an F.</p>
<p>With a grading system like this, it’s not surprising that opponents of climate action have found ways to reject global warming research, despite the overwhelming evidence.</p>
<p>Here’s how they do it:</p>
<h2>The all-or-nothing problem</h2>
<p>Climate change deniers simplify the spectrum of possible scientific consensus into two categories: 100% agreement or no consensus at all. If it’s not one, it’s the other.</p>
<p>A 2021 review of thousands of climate science papers and conference proceedings concluded that over 99% of studies have found that burning <a href="https://doi.org/10.1088/1748-9326/ac2966">fossil fuels warms the planet</a>. That’s not good enough for some skeptics. If they find one contrarian scientist somewhere, they categorize the idea of human-caused global warming as controversial and <a href="https://e360.yale.edu/features/freeman_dyson_takes_on_the_climate_establishment">conclude that there is no basis for action</a>.</p>
<p>Powerful economic interests are at work here: The fossil fuel industry has funded disinformation campaigns for years to <a href="https://news.harvard.edu/gazette/story/2021/09/oil-companies-discourage-climate-action-study-says">create this kind of doubt about climate change</a>, despite <a href="https://theconversation.com/what-big-oil-knew-about-climate-change-in-its-own-words-170642">knowing that their products cause it and the consequences</a>. Members of Congress have <a href="https://www.eenews.net/articles/trumps-climate-denial-shapes-house-gop-backbench/">used that disinformation</a> to block or weaken federal policies that could slow climate change.</p>
<h2>Expecting a straight line in a variable world</h2>
<p>In another example of black-and-white thinking, deniers argue that if global temperatures are not increasing at a perfectly consistent rate, there is no such thing as global warming. </p>
<p>However, complex variables never change in a uniform way; they wiggle up and down in the short term even when exhibiting long-term trends. Most business data, such as revenues, profits and stock prices, do this too, with short-term fluctuations contained in long-term trends.</p>
<figure class="align-center ">
<img alt="Charts showing Apple's changing stock price and global temperatures over time. Both have a saw-tooth pattern." src="https://images.theconversation.com/files/523304/original/file-20230427-18-w7d3zk.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/523304/original/file-20230427-18-w7d3zk.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=437&fit=crop&dpr=1 600w, https://images.theconversation.com/files/523304/original/file-20230427-18-w7d3zk.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=437&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/523304/original/file-20230427-18-w7d3zk.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=437&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/523304/original/file-20230427-18-w7d3zk.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=550&fit=crop&dpr=1 754w, https://images.theconversation.com/files/523304/original/file-20230427-18-w7d3zk.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=550&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/523304/original/file-20230427-18-w7d3zk.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=550&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">These two graphs have the same form: a long-term trend of major increase within which there are short-term fluctuations.</span>
<span class="attribution"><a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Mistaking a cold snap for disproof of climate change is like mistaking <a href="https://www.macrotrends.net/stocks/charts/AAPL/apple/market-value">a bad month for Apple stock</a> for proof that Apple isn’t a good long-term investment. This error results from homing in on a tiny slice of the graph and ignoring the rest.</p>
<h2>Failing to examine the gray area</h2>
<p>Climate change deniers also mistakenly cite correlations below 100% as evidence against human-caused global warming. They triumphantly point out that sunspots and volcanic eruptions also affect the climate, even though evidence shows both have <a href="https://nca2018.globalchange.gov/chapter/2/">very little influence on long-term temperature rise</a> in comparison to greenhouse gas emissions.</p>
<p>In essence, deniers argue that if fossil fuel burning is not all-important, it’s unimportant. They miss the gray area in between: Greenhouse gases are indeed just one factor warming the planet, but they’re the most important one and the factor humans can influence.</p>
<figure class="align-center ">
<img alt="Charts showing impact of different forces on temperature. Natural sources have little variation, but the upward swing of temperatures corresponds closely with rising greenhouse gas emissions." src="https://images.theconversation.com/files/523071/original/file-20230426-1510-itdelq.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/523071/original/file-20230426-1510-itdelq.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=738&fit=crop&dpr=1 600w, https://images.theconversation.com/files/523071/original/file-20230426-1510-itdelq.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=738&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/523071/original/file-20230426-1510-itdelq.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=738&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/523071/original/file-20230426-1510-itdelq.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=927&fit=crop&dpr=1 754w, https://images.theconversation.com/files/523071/original/file-20230426-1510-itdelq.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=927&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/523071/original/file-20230426-1510-itdelq.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=927&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Influences on global temperature over time.</span>
<span class="attribution"><a class="source" href="https://nca2018.globalchange.gov/chapter/2/">4th National Climate Assessment</a></span>
</figcaption>
</figure>
<h2>‘The climate has always been changing’ – but not like this</h2>
<p>As increases in global temperatures have become obvious, some climate change skeptics have switched from denying them to reframing them.</p>
<p>Their oft-repeated line, “The climate has always been changing,” typically delivered with an air of patient wisdom, is based on a striking lack of knowledge about the <a href="https://climate.nasa.gov/evidence/">evidence from climate research</a>.</p>
<p>Their reasoning is based on an invalid binary: Either the climate is changing or it’s not, and since it’s always been changing, there is nothing new here and no cause for concern.</p>
<p>However, the current warming is on par with <a href="https://www.science.org/doi/abs/10.1126/science.1228026">nothing humans have ever seen</a>, and intense warming events in the distant past were planetwide <a href="https://www.washington.edu/news/2018/12/06/biggest-extinction-in-earths-history-caused-by-global-warming-leaving-ocean-animals-gasping-for-breath/">disasters that caused massive extinctions</a> – something we do not want to repeat.</p>
<p>As humanity faces the challenge of global warming, we need to use all our cognitive resources. Recognizing the thinking error at the root of climate change denial could disarm objections to climate research and make science the basis of our efforts to preserve a hospitable environment for our future.</p><img src="https://counter.theconversation.com/content/204607/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jeremy P. Shapiro 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 psychologist explains how opponents of climate policies use a common thinking error to manipulate the public – and why people are so susceptible.Jeremy P. Shapiro, Adjunct Assistant Professor of Psychological Sciences, Case Western Reserve UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2043592023-04-26T20:03:10Z2023-04-26T20:03:10ZFear and Wonder podcast: how species are responding to climate change – and how humans can help<figure><img src="https://images.theconversation.com/files/522464/original/file-20230424-28-vj5jul.jpg?ixlib=rb-1.1.0&rect=0%2C5%2C1997%2C1323&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Lake ice in Ruka, Finland.</span> <span class="attribution"><span class="source">Tom Roeleveld/flickr</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span></figcaption></figure><p>Around half of all life on Earth is on the move because of climate change, according to the Intergovernmental Panel on Climate Change (IPCC). Many species’ habitats are changing, forcing them to move, while others are fleeing harm’s way as new predators move in.</p>
<p>This staggering statistic shows just one of the ways climate change is impacting species at both ends of the Earth. In this week’s episode of The Conversation’s climate podcast Fear & Wonder, we travel from the Arctic to Tasmania to see how these changes are playing out.</p>
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<p>The <a href="https://www.ipcc.ch/report/sixth-assessment-report-working-group-ii/">second volume</a> of the IPCC’s monumental Sixth Assessment Report assesses the impacts, adaptation and vulnerability of people and ecosystems to global warming, including how animals and plants are responding to a changing climate.</p>
<p>In this episode, we speak to Finnish fisherman and IPCC scientist Tero Mustonen about the changes he has observed on the lake ice in his village of Selkie in North Karelia, and how his community has led a successful rewilding project on a nearby peatland mining site.</p>
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Read more:
<a href="https://theconversation.com/introducing-fear-and-wonder-the-conversations-new-climate-podcast-200066">Introducing Fear and Wonder: The Conversation's new climate podcast</a>
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<p>We also hear from Australian marine ecologist and IPCC author Gretta Pecl, whose research has helped map the rapid redistribution of life on Earth. Through her dives off the Tasmanian coast, we learn how species are shifting their distribution faster in the ocean than they are on land.</p>
<p>To listen and subscribe, click <a href="https://shows.acast.com/fear-and-wonder-stories-from-un-climate-experts">here</a>, or click the icon for your favourite podcast app in the graphic above.</p>
<p>If you’re enjoying Fear & Wonder, be sure to join us for a live bonus episode at 1pm on May 1. Details <a href="https://theconversation.com/join-us-for-the-fear-and-wonder-podcast-live-bonus-episode-204268">here</a>.</p>
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<p><em>Fear and Wonder is sponsored by the <a href="https://www.climatecouncil.org.au/">Climate Council</a>, an independent, evidence-based organisation working on climate science, impacts and solutions.</em></p><img src="https://counter.theconversation.com/content/204359/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Dr Joelle Gergis has received funding from the Australian Research Council and the Australian Government's Department of Industry, Science, Energy and Resources in the past. She currently receives funding from the Australian National University.</span></em></p><p class="fine-print"><em><span>Michael Green 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>Fear and Wonder is a new climate podcast, brought to you by The Conversation, and sponsored by the Climate Council. In episode five, we discuss how climate change is affecting vulnerable species.Joelle Gergis, Senior Lecturer in Climate Science, Australian National UniversityMichael Green, Host + Producer, The ConversationLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2044802023-04-26T10:19:41Z2023-04-26T10:19:41Z‘Statistically impossible’ heat extremes are here – we identified the regions most at risk<figure><img src="https://images.theconversation.com/files/522795/original/file-20230425-28-465ac1.jpg?ixlib=rb-1.1.0&rect=13%2C0%2C4587%2C2586&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Ed Connor / shutterstock</span></span></figcaption></figure><p>In the summer of 2021, Canada’s all-time temperature record was smashed by almost 5°C. Its new record of 49.6°C is hotter than anything ever recorded in Spain, Turkey or indeed anywhere in Europe. </p>
<p>The record was set in Lytton, a small village a few hours’ drive from Vancouver, in a part of the world that doesn’t really look like it should experience such temperatures.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/522789/original/file-20230425-14-kacc5w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Wide valley with trees" src="https://images.theconversation.com/files/522789/original/file-20230425-14-kacc5w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/522789/original/file-20230425-14-kacc5w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/522789/original/file-20230425-14-kacc5w.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/522789/original/file-20230425-14-kacc5w.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/522789/original/file-20230425-14-kacc5w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/522789/original/file-20230425-14-kacc5w.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/522789/original/file-20230425-14-kacc5w.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">Hotter than anywhere in Europe or South America, ever: Fraser River near Lytton, in British Columbia, Canada.</span>
<span class="attribution"><span class="source">Harry Beugelink / shutterstock</span></span>
</figcaption>
</figure>
<p>Lytton was the peak of a heatwave that hit the Pacific Northwest of the US and Canada that summer and left many scientists shocked. From a purely statistical point of view, it should have been impossible.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1410157638109872134"}"></div></p>
<p>I’m part of a team of climate scientists who wanted to find out if the Pacific Northwest heatwave was unique, or whether any other regions had experienced such statistically implausible events. And we wanted to assess which regions were most at risk in future. Our results are now published in the journal <a href="https://www.nature.com/articles/s41467-023-37554-1">Nature Communications</a>.</p>
<p>Tracking these outlier heatwaves is important not just because the heatwaves themselves are dangerous, but because countries tend to prepare to around the level of the most extreme event within collective memory. An unprecedented heatwave can therefore provoke policy responses to reduce the impact of future heat.</p>
<p>For instance, a severe heatwave in Europe in 2003 is estimated to have caused <a href="https://www.undrr.org/publication/human-cost-disasters-overview-last-20-years-2000-2019">50,000-70,000 excess deaths.</a> Although there have been more intense heatwaves since, none have resulted in such a high death toll, due to management plans implemented in the wake of 2003.</p>
<p>One of the most important questions when studying these extreme heatwaves is “how long do we have to wait until we experience another similarly intense event?”. This is a challenging question but, fortunately, there is a branch of statistics, called extreme value theory, that provides ways in which we can answer that exact question using past events. </p>
<p>But the Pacific Northwest heatwave is one of several recent events that have challenged this method and should not have been possible according to extreme value theory. This “breakdown” of statistics is caused by conventional extreme value theory not taking into account the specific combination of physical mechanisms, which may not exist in the events contained in the historical record. </p>
<h2>Implausible heat is everywhere</h2>
<p>Looking at historical data from 1959 to 2021, we found that 31% of Earth’s land surface has already experienced such statistically implausible heat (though the Pacific Northwest heatwave is exceptional even among these events). These regions are spread all across the globe with no clear spatial pattern. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/522818/original/file-20230425-1269-6b7nse.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Wooden houses by a large bay filled with ice bergs" src="https://images.theconversation.com/files/522818/original/file-20230425-1269-6b7nse.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/522818/original/file-20230425-1269-6b7nse.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=199&fit=crop&dpr=1 600w, https://images.theconversation.com/files/522818/original/file-20230425-1269-6b7nse.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=199&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/522818/original/file-20230425-1269-6b7nse.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=199&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/522818/original/file-20230425-1269-6b7nse.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=250&fit=crop&dpr=1 754w, https://images.theconversation.com/files/522818/original/file-20230425-1269-6b7nse.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=250&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/522818/original/file-20230425-1269-6b7nse.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=250&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 heatwave in September 2022 meant Greenland’s ice sheets kept melting for a month longer than usual.</span>
<span class="attribution"><span class="source">muratart / shutterstock</span></span>
</figcaption>
</figure>
<p>We also drew similar conclusions when we analysed “large ensemble” data produced by climate models, which involve computers simulating the global climate many times over. These simulations are extremely useful for us, since the effective length of this simulated “historical record” is far larger and thus they produce many more examples of rare events.</p>
<p>However, while this analysis of the most exceptional events is interesting, and cautions against using purely statistical approaches for assessing the limits to physical extremes, the most important conclusions of our work come from the other end of the spectrum – regions that have not experienced particularly extreme events before.</p>
<h2>Some places have got lucky – so far</h2>
<p>We identified a number of regions, again spread across the globe, that have not experienced especially extreme heat over the past six decades (relative to their “expected” climate). As a result, these regions are more likely to see a record-breaking event in the near future. And with no experience of such a huge outlier, and less incentive to prepare for one, they may be particularly harmed by a record heatwave. </p>
<p>Socioeconomic factors, including population size, population growth and level of development will exacerbate these impacts. As a result, we factor in population and economic development projections in our assessment of the regions that are most at risk globally. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/522796/original/file-20230425-24-glrns8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Man in colourful market" src="https://images.theconversation.com/files/522796/original/file-20230425-24-glrns8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/522796/original/file-20230425-24-glrns8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/522796/original/file-20230425-24-glrns8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/522796/original/file-20230425-24-glrns8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/522796/original/file-20230425-24-glrns8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/522796/original/file-20230425-24-glrns8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/522796/original/file-20230425-24-glrns8.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">Central America hasn’t been hit with a truly severe heatwave – yet.</span>
<span class="attribution"><span class="source">streetflash / shutterstock</span></span>
</figcaption>
</figure>
<p>Our at-risk regions include Afghanistan, several countries in Central America and far eastern Russia among others. These regions may be surprising, since they are not those people typically think of when considering extreme heat impacts of climate change like India or the Persian Gulf. But those countries have recently <a href="https://www.theguardian.com/weather/2023/apr/19/severe-heatwave-asia-deaths-schools-close-india-china">experienced severe heatwaves</a> and so are already doing what they can to prepare.</p>
<p>Central Europe and several provinces in China, including the area around Beijing, also appear to be vulnerable when considering the extremeness of the record and population size, but as more developed areas they are likely to already have plans to mitigate severe impacts.</p>
<p>Overall, our work raises two important points:</p>
<p>The first is that statistically implausible heatwaves can occur anywhere on the Earth, and we must be very cautious about using the historical record in isolation to estimate the “maximum” heatwave possible. Policymakers across the globe should prepare for exceptional heatwaves that would be deemed implausible based on current records.</p>
<p>The second is that there are a number of regions whose historical record is not exceptional, and therefore is more likely to be broken. These regions have been lucky so far, but as a result, are likely to be less well prepared for an unprecedented heatwave in the near future. It is especially important that these regions prepare for more intense heatwaves than they have already experienced.</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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<p class="fine-print"><em><span>Nicholas Leach has received funding from NERC. Alongside his academic role he works for Climate X, a climate risk analytics start-up.</span></em></p>Afghanistan and Central America have growing populations, limited resources, and the potential for more extreme heatwaves.Nicholas Leach, Postdoctoral Researcher, Climate Science, University of OxfordLicensed as Creative Commons – attribution, no derivatives.