tag:theconversation.com,2011:/ca/topics/greenhouse-effect-18270/articlesGreenhouse effect – The Conversation2024-02-23T17:16:47Ztag:theconversation.com,2011:article/2236182024-02-23T17:16:47Z2024-02-23T17:16:47ZSatellites are burning up in the upper atmosphere – and we still don’t know what impact this will have on the Earth’s climate<figure><img src="https://images.theconversation.com/files/577600/original/file-20240223-16-tqd752.jpg?ixlib=rb-1.1.0&rect=25%2C16%2C5566%2C4174&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-illustration/satellite-hurtling-through-space-burning-enters-113962255">Paul Fleet / shutterstock</a></span></figcaption></figure><p>Elon Musk’s SpaceX has announced it will dispose of 100 Starlink satellites over the next six months, after it <a href="https://spacenews.com/spacex-to-deorbit-100-older-starlink-satellites/">discovered a design flaw</a> that may cause them to fail. Rather than risk posing a threat to other spacecraft, SpaceX will “de-orbit” these satellites to burn up in the atmosphere. </p>
<p>But atmospheric scientists are increasingly concerned that this sort of <a href="https://www.cbc.ca/radio/quirks/study-space-junk-pollution-1.7010373">apparent fly-tipping</a> by the space sector will cause further climate change down on Earth. One team recently, and unexpectedly, found <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10614211/">potential ozone-depleting metals</a> from spacecraft in the stratosphere, the atmospheric layer where the ozone layer is formed. </p>
<p>The relative “low earth orbit” where <a href="https://www.copernicus.eu/en/about-copernicus/infrastructure-overview/discover-our-satellites">satellites</a> monitoring Earth’s <a href="https://www.copernicus.eu/en">ecosystems</a> are found is increasingly congested – Starlink alone has more than 5,000 spacecraft in orbit. Clearing debris is therefore a priority for the space sector. Newly launched spacecraft must also be removed from orbit within 25 years (the US recently implemented a stricter <a href="https://www.fcc.gov/document/fcc-adopts-new-5-year-rule-deorbiting-satellites-0">five-year rule</a>) either by moving upwards to a so-called “graveyard orbit” or down into the Earth’s atmosphere. </p>
<p>Lower orbiting satellites are usually designed to use any remaining fuel and the pull of the Earth’s gravity to re-enter the atmosphere. In a controlled reentry, the spacecraft enters the atmosphere at a pre-set time to land in the most remote part of the Pacific Ocean at <a href="https://explorersweb.com/point-nemo-spacecraft-graveyard/">Point Nemo</a> (aka the spacecraft cemetery). In an uncontrolled re-entry, spacecraft are left to follow a “natural demise” and burn up in the atmosphere.</p>
<p>Nasa and the European Space Agency promote this form of disposal as part of a design philosophy called “design for demise”. It is an environmental challenge to build, launch and operate a satellite robust enough to function in the hostility of space yet also able to break up and burn up easily on re-entry to avoid dangerous debris reaching the Earth’s surface. It’s still a work in progress.</p>
<p>Satellite operators must prove their design and re-entry plans have a low “human-hit” rate before they are awarded a license. But there is limited concern regarding the impact on Earth’s upper atmosphere during the re-entry stage. This is not an oversight.</p>
<p>Initially, neither the space sector nor the astrophysics community considered burning up satellites on re-entry to be a serious environmental threat – to the atmosphere, at least. After all, the number of spacecraft particles released is small when compared with 440 tonnes of <a href="https://science.nasa.gov/solar-system/meteors-meteorites/">meteoroids</a> that enter the atmosphere daily, along with volcanic ash and human-made pollution from industrial processes on Earth.</p>
<h2>Bad news for the ozone layer?</h2>
<p>So are atmospheric climate scientists overreacting to the presence of spacecraft particles in the atmosphere? Their concerns draw on 40 years of research into the cause of the ozone holes above the south and north poles, that were first widely observed in the 1980s. </p>
<p>Today, they now know that ozone loss is caused by human-made <a href="https://gml.noaa.gov/hats/publictn/elkins/cfcs.html#:%7E:text=Chlorofluorocarbons%20(CFCs)%20are%20nontoxic%2C,as%20solvents%2C%20and%20as%20refrigerants.">industrial gases</a>, which combine with natural and very high altitude <a href="https://www.bas.ac.uk/data/our-data/publication/polar-stratospheric-clouds-satellite-observations-processes-and-role-in-ozone/">polar stratospheric clouds</a> or mother of pearl clouds. The surfaces of these ethereal clouds act as catalysts, turning benign chemicals into more active forms that can rapidly <a href="https://uk-air.defra.gov.uk/research/ozone-uv/moreinfo?view=arctic-ozone-hole">destroy ozone</a>.</p>
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<span class="caption">Mother of pearl cloud in the stratosphere above Norway.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/mother-pearl-cloud-norway-245-1849794832">Uwe Michael Neumann / shutterstock</a></span>
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<p>Dan Cziczo is an atmospheric scientist at Purdue University in the US, and a co-author of the recent study that found ozone depleting substances in the stratosphere. He explains to me that the question is whether the new particles from spacecraft will help the formation of these clouds and lead to ozone loss at a time when the Earth’s atmosphere is just <a href="https://theconversation.com/how-science-saved-the-ozone-layer-218839">beginning to recover</a>. </p>
<p>Of more concern to atmospheric scientists such as Cziczo is that only a few new particles could create more of these types of polar clouds – not only at the upper atmosphere, but also in the lower atmosphere, where cirrus clouds form. Cirrus clouds are the thin, wispy ice clouds you might spot high in the sky, above six kilometres. They tend to let heat from the sun pass through but then trap it on the way out, so in theory more cirrus clouds could add extra global warming on top of what we are already seeing from greenhouse gases. But this is uncertain and <a href="https://blogs.esa.int/campaignearth/2023/03/23/in-the-icy-mountains-of-norway-a-fons-researcher-is-studying-how-clouds-affect-global-warming/">still being studied</a>.</p>
<p>Cziczo also explains that from anecdotal evidence we know that the high-altitude clouds above the poles are changing – but we don’t know yet what is causing this change. Is it natural particles such as meteoroids or volcanic debris, or unnatural particles from spacecrafts? This is what we need to know.</p>
<h2>Concerned, but not certain</h2>
<p>So how do we answer this question? We have some research from atmospheric scientists, spacecraft builders and astrophysicists, but it’s not rigorous or focused enough to make informed decisions on which direction to take. Some astrophysicists claim that alumina (aluminium oxide) particles from spacecraft will cause chemical reactions in the atmosphere that <a href="https://www.space.com/starlink-satellite-reentry-ozone-depletion-atmosphere">will likely trigger ozone destruction</a>. </p>
<p>Atmospheric scientists who study this topic in detail have not made this jump as there isn’t enough scientific evidence. We know particles from spacecraft are in the stratosphere. But what this means for the ozone layer or the climate is still unknown.</p>
<p>It is tempting to overstate research findings to garner more support. But this is the path to research hell – and deniers will use poor findings at a later date to discredit the research. We also don’t want to use populist opinions. But we’ve also learnt that if we wait until indisputable evidence is available, it may be too late, as with the loss of ozone. It’s a constant dilemma.</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>Fionagh Thomson has carried out consultancy work for the UK space agency. She is an elected member of the sustainability committees for the Royal Astronomical Society and the European Astronomical society. </span></em></p>We know particles from spacecrafts are in the stratosphere. But what this means for the ozone layer or the climate is still unknown.Fionagh Thomson, Senior Research Fellow (visual ethnographer), Durham UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2175822024-01-21T08:55:58Z2024-01-21T08:55:58ZCongo’s blackwater Ruki River is a major transporter of forest carbon - new study<figure><img src="https://images.theconversation.com/files/559590/original/file-20231115-29-kv00ye.jpg?ixlib=rb-1.1.0&rect=0%2C17%2C3888%2C2892&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">River Ruki. </span> <span class="attribution"><span class="source">Photo by Matti Barthel</span>, <span class="license">Author provided</span></span></figcaption></figure><p>The Congo Basin of central Africa is well known for its network of rivers that drain a variety of <a href="https://www.britannica.com/place/Congo-Basin">landscapes</a>, from dense tropical forests to more arid and wooded savannas. Among the Congo River’s large tributaries, the Ruki is unique in its extremely <a href="https://www.iflscience.com/why-the-ruki-may-be-the-worlds-darkest-river-71206">dark colour</a>, which renders the water opaque below a few centimetres’ depth. </p>
<p>This large blackwater river caught the attention of our carbon biogeochemistry research team when we visited its confluence with the Congo River at the city of Mbandaka. Mbandaka is a small city in the Democratic Republic of Congo, located about 600km upstream from Kinshasa on the Congo River. The area around Mbandaka is known as the Cuvette Centrale and is characterised by its vast low-lying topography, much of which floods during the rainy season and results in extensive swamp forests.</p>
<p>As we watched the placid dark water of the Ruki flow by, we wondered just how much carbon this river was transporting and where it came from. To answer these questions, we decided to measure the carbon in the Ruki for one year to account for seasonal changes. </p>
<p>The results of this <a href="https://aslopubs.onlinelibrary.wiley.com/doi/full/10.1002/lno.12436">study</a> show that the Ruki is a major contributor of dissolved carbon to the Congo River, and that the majority of this carbon is sourced from the leaching of forest vegetation and soils. These results also suggest that the way in which calculations are made about how much carbon tropical forests accumulate might be off the mark – perhaps slightly overestimated.</p>
<p>These findings are important because rivers are major conduits of carbon from land to ocean and atmosphere, supplying organic matter to downstream ecosystems and carbon dioxide to the air. It is important to quantify how much carbon they are moving, where it is coming from, and where it ends up. Such accounting helps scientists understand how different ecosystems function, what role they play in the <a href="https://en.wikipedia.org/wiki/Carbon_cycle">carbon cycle</a>, and how they might respond to future or ongoing human perturbations such as climate or land-use change.</p>
<h2>The heart of the forest</h2>
<p>The Ruki River lies at the centre of the Congo Basin. It drains a uniquely homogeneous 188,800km² of pristine lowland and swamp forests. Since climate, vegetation, soils, geology and the concentration of human impacts vary widely across Earth’s surface, it’s uncommon for a watershed of this size to have such uniform land cover. There are likely no other such uniform watersheds of this size on earth.</p>
<p>This means we had an opportunity to pinpoint how a specific land cover influences the quantity and composition of organic material leached from decomposing plants and soils and carried by rainwater to river channels. Knowing this, we can “unmix” the signals measured in the Congo River and better ascertain the differences in carbon export between the many tributaries and land covers of the basin.</p>
<p>We <a href="https://aslopubs.onlinelibrary.wiley.com/doi/full/10.1002/lno.12436">found</a> that Ruki supplies 20% of the dissolved carbon in the Congo River though it makes up only 5% of the Congo’s watershed by area. This contribution is so high because the Ruki’s water is extremely concentrated in dissolved organic matter. In fact, it is significantly richer in dissolved carbon than even the Amazon’s Rio Negro (“Black River”), which is famous for its black colour also stemming from <a href="https://onlinelibrary.wiley.com/doi/abs/10.1002/hyp.1291">high concentration of organics</a>. </p>
<p>Water with very high concentrations of organic matter signals neither a good nor bad thing. It just means lots of carbon is contained in the water.</p>
<p>Because the Ruki watershed is so flat, rainwater drains slowly and has plenty of time to leach organic material from its dense vegetation. It’s like leaving multiple bags of tea to steep in water over a long period of time. </p>
<p>One of the reasons we wanted to know where these organic compounds were originating from is that large areas of the Ruki are underlain by enormous tracts of peat-like soils. These organic-rich soils have accumulated over hundreds to thousands of years from the buildup of partially decomposed plant matter. </p>
<p>If this peat was being leached or eroded into the river, through some form of disturbance, it could be <a href="https://peatlands.org/peatlands/peatlands-and-climate/">released</a> as carbon dioxide into the atmosphere and compound the greenhouse effect, much like the unearthing and combustion of fossil fuels. </p>
<p>Our radiocarbon isotopic measurements of the dissolved carbon indicate that there is very little peat carbon entering the river (none of it is very old), and that the dissolved carbon is sourced instead from forest vegetation and recently formed soil.</p>
<p>This is good news for now, but it’s something to keep an eye on if periods of drought or human activity disturb these carbon-rich peat soils. </p>
<h2>Balancing the forest sink</h2>
<p>Why does it matter if the Ruki transports a large amount of carbon?</p>
<p>One answer is that the carbon lost from terrestrial ecosystems to rivers can determine whether forests are taking up more carbon from the atmosphere (sinks) than releasing it (source) to the atmosphere. Most assessments of the balance (carbon coming in versus carbon going out of a forest) fail to account for the carbon that moves laterally to rivers. </p>
<p>In the case of the Ruki, the high amount of carbon that is contained in the river per unit area of the watershed suggests that this lateral movement of carbon from the Congo’s lowland forests comprises a significant proportion of the carbon balance, that is, the difference between what is coming in from photosynthesis and what is returned via respiration. </p>
<p>Thus, tropical forests like those around the Ruki might not accumulate quite as much carbon as we once thought. Further research is required to pin down whether this is the case. But our work on the Ruki already indicates that areas drained by such blackwater rivers may be particularly prone to carbon accounting errors like this.</p><img src="https://counter.theconversation.com/content/217582/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Travis Drake received funding from the Swiss National Science Fund.</span></em></p><p class="fine-print"><em><span>Johan Six received funding from Swiss National Science Fund. </span></em></p><p class="fine-print"><em><span>Matti Barthel receives funding from Swiss National Science Fund.</span></em></p>The Ruki River supplies dissolved carbon from forest vegetation and soils to the Congo River.Travis Drake, Postdoctoral Researcher, Swiss Federal Institute of Technology ZurichJohan Six, Professor of Sustainable Agrosystems, Swiss Federal Institute of Technology ZurichMatti Barthel, Research Technician, Swiss Federal Institute of Technology ZurichLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2143612023-12-04T22:49:02Z2023-12-04T22:49:02ZWhat happens after net zero? The impacts will play out for decades, with poorest countries still feeling the heat<p>Humanity’s emissions of greenhouse gases have caused rapid <a href="https://www.ipcc.ch/report/ar6/syr/resources/spm-headline-statements/">global warming</a> at a rate unprecedented in at least the past 2,000 years. Rapid global warming has been accompanied by increases in the frequency and intensity of heat extremes over most land regions in the past 70 years. </p>
<p>While human activities cause emissions of a number of greenhouse gases, carbon dioxide (CO₂) stands out as the leading culprit. This is because of its relatively long atmospheric lifetime and because human activities cause much <a href="https://www.epa.gov/ghgemissions/global-greenhouse-gas-emissions-data">higher emissions of CO₂</a> than other greenhouse gases. </p>
<p>To avoid reaching unsafe global temperatures, <a href="https://www.ipcc.ch/sr15/chapter/spm/">climate scientists have concluded</a> we can’t prevent continued global warming without reaching a state of net zero CO₂ emissions.</p>
<p>But how might climate extremes change after net zero CO₂? There is limited research on this. Our new study, <a href="https://iopscience.iop.org/article/10.1088/1748-9326/ad114a">published in Environmental Research Letters</a>, uses a collection of models to address this gap. We found temperatures would respond very differently in various parts of the world, and heat extremes might continue to disproportionately affect vulnerable populations.</p>
<h2>The greenhouse effect and net zero emissions</h2>
<p>The world’s land and oceans have taken up most of the carbon humanity has emitted over the past six decades. However, land and oceans are incapable of absorbing 100% of CO₂ emissions.</p>
<p>The remaining CO₂ emissions over the past 60 years have been absorbed by the atmosphere, leading to an enhanced <a href="https://climate.nasa.gov/faq/19/what-is-the-greenhouse-effect/">greenhouse effect</a>. This has caused the especially rapid warming we’ve observed in the recent past. </p>
<p>To stop the continued enhancement of the greenhouse effect, we need to reach <a href="https://netzeroclimate.org/what-is-net-zero-2/">net zero</a> CO₂ emissions. Achieving net zero means reaching an overall balance between the CO₂ emissions humans produce and the CO₂ humans remove from the atmosphere.</p>
<p>The urgency of reaching net zero CO₂ emissions has sparked the use of state-of-the-art climate modelling techniques to answer the question – how does our climate change after net zero?</p>
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Read more:
<a href="https://theconversation.com/how-could-australia-actually-get-to-net-zero-heres-how-217778">How could Australia actually get to net zero? Here's how</a>
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<h2>What lies beyond net zero CO₂?</h2>
<p>To try and answer this question, we used climate simulation models with increasing carbon dioxide in the atmosphere. Then, CO₂ emissions are “turned off” and simulations continue for 100 years more. This simple experimental setup allows us to compare the climate before net zero to climate patterns we might see after a transition to net zero.</p>
<p>There are regions where projected climate change patterns after net zero CO₂ are very uncertain. However, we saw several strong patterns:</p>
<ol>
<li><p>land cools after net zero CO₂ is achieved, while the ocean takes a bit more time to respond with some areas cooling and others warming;</p></li>
<li><p>the Southern Ocean continues to warm after net zero CO₂;</p></li>
<li><p>global temperature change (-0.23°C) is not always a good representation of regional temperature changes.</p></li>
</ol>
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<span class="caption">Change in regional temperature after net zero carbon dioxide emissions. Cross-hatching indicates areas where we are confident that regional temperatures increase (red hues) or decrease (blue hues).</span>
<span class="attribution"><span class="source">Author provided</span></span>
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<h2>Heat extreme patterns after net zero CO₂</h2>
<p>Currently, less economically developed regions experience <a href="https://www.ipcc.ch/report/ar6/wg2/chapter/chapter-8/">disproportionate loss and damage</a> from climate extremes. Should we expect this to persist after net zero CO₂ emissions, or will the inequality of climate change be resolved by net zero? </p>
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Read more:
<a href="https://theconversation.com/cop28-climate-summit-just-approved-a-loss-and-damage-fund-what-does-this-mean-218999">COP28 climate summit just approved a 'loss and damage' fund. What does this mean?</a>
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<p>We explored this issue by investigating if there are any changes in how often local heat extremes occur 100 years after net zero compared to how often they occur before net zero.</p>
<p>We then compared our results to maps of the <a href="https://hdr.undp.org/data-center/human-development-index#/indicies/HDI">Human Development Index</a> – a measure of socioeconomic development where regions with a high rank have higher incomes, more access to education and longer life expectancy. Other similar development indicators include <a href="https://hdr.undp.org/content/2023-global-multidimensional-poverty-index-mpi#/indicies/MPI">the Multidimensional Poverty Index</a>.</p>
<p>Although there are widespread decreases in how often heat extremes occur after net zero CO₂ emissions, regions with a relatively higher human development index such as North America and western Europe experience larger reductions in heat extremes than regions with a lower rank, such as Sub-Saharan Africa and southeast Asia.</p>
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<a href="https://images.theconversation.com/files/550260/original/file-20230926-25-uifg91.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/550260/original/file-20230926-25-uifg91.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/550260/original/file-20230926-25-uifg91.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=838&fit=crop&dpr=1 600w, https://images.theconversation.com/files/550260/original/file-20230926-25-uifg91.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=838&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/550260/original/file-20230926-25-uifg91.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=838&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/550260/original/file-20230926-25-uifg91.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1053&fit=crop&dpr=1 754w, https://images.theconversation.com/files/550260/original/file-20230926-25-uifg91.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1053&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/550260/original/file-20230926-25-uifg91.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1053&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Top: change in how often heat extremes occur regionally after net zero. Cross-hatching indicates areas where we are confident that heat extremes become more frequent (green hues) or less frequent (purple hues). Bottom: human development index in 2015.</span>
<span class="attribution"><span class="source">Author provided</span></span>
</figcaption>
</figure>
<h2>Preparing for a post net zero world</h2>
<p>We need to reach and sustain net zero CO₂ emissions to halt continued global warming. Models that emulate the transition to net zero CO₂ project large-scale cooling over land, and widespread reduction in land-based heat extremes.</p>
<p>However, post-net zero reductions in heat extremes favour regions with a higher human development index over regions with a lower index. This means the inequality of climate change may persist even after net zero CO₂. </p>
<p>Our study represents a step toward understanding climate extremes after net zero CO₂ emissions are achieved. For now, it is imperative that humanity works without delay to achieve net zero emissions to avoid the most severe climate change impacts affecting future generations.</p>
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Read more:
<a href="https://theconversation.com/emissions-inequality-is-getting-worse-heres-how-to-end-the-reign-of-the-ultra-polluters-218308">Emissions inequality is getting worse – here's how to end the reign of the ultra-polluters</a>
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<img src="https://counter.theconversation.com/content/214361/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><p class="fine-print"><em><span>Josephine Brown receives funding from the National Environmental Science Program.</span></em></p><p class="fine-print"><em><span>Tilo Ziehn receives funding from the Australian Government under the National Environmental Science Program.</span></em></p><p class="fine-print"><em><span>Liam Cassidy 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>We can’t prevent continued global warming without reaching net zero carbon dioxide emissions. New climate simulations show what might happen when we get there.Liam Cassidy, PhD Candidate, The University of MelbourneAndrew King, Senior Lecturer in Climate Science, The University of MelbourneJosephine Brown, Senior Lecturer, The University of MelbourneTilo Ziehn, Principal Research Scientist, CSIROLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2137612023-11-05T23:16:31Z2023-11-05T23:16:31ZOur minds handle risk strangely – and that’s partly why we delayed climate action so long<figure><img src="https://images.theconversation.com/files/557060/original/file-20231101-21-2vg3lq.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C3512%2C2212&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>We now have a very narrow window to significantly and rapidly slash greenhouse gas emissions to avoid the most disastrous effects of climate change, with just an estimated <a href="https://theconversation.com/carbon-budget-for-1-5-c-will-run-out-in-six-years-at-current-emissions-levels-new-research-216459">six years left</a> before we blow our carbon budget to stay below 1.5°C of warming. </p>
<p>We’ve known how gases like carbon dioxide trap heat for <a href="https://theconversation.com/scientists-understood-physics-of-climate-change-in-the-1800s-thanks-to-a-woman-named-eunice-foote-164687">over 100 years</a> and alarm bells have been ringing loudly for over 35 years, when climate scientist James Hansen testified that <a href="https://www.nytimes.com/1988/06/24/us/global-warming-has-begun-expert-tells-senate.html">global warming had begun</a>. </p>
<p>As extreme weather and temperatures arrive, many of us wonder whether it had to get this bad before we acted. Did we need to see to believe? What role has our own psychology played in our sluggishness? </p>
<figure class="align-center ">
<img alt="james hansen testifying before US senate" src="https://images.theconversation.com/files/557061/original/file-20231101-17-cgom4l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/557061/original/file-20231101-17-cgom4l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=417&fit=crop&dpr=1 600w, https://images.theconversation.com/files/557061/original/file-20231101-17-cgom4l.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=417&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/557061/original/file-20231101-17-cgom4l.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=417&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/557061/original/file-20231101-17-cgom4l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=524&fit=crop&dpr=1 754w, https://images.theconversation.com/files/557061/original/file-20231101-17-cgom4l.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=524&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/557061/original/file-20231101-17-cgom4l.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=524&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Many people first took notice of climate change after US scientist James Hansen testified about its effects.</span>
<span class="attribution"><span class="source">NASA</span></span>
</figcaption>
</figure>
<h2>How do we respond to threats?</h2>
<p>From a psychology point of view, motivating us to take action on climate is a <a href="https://theconversation.com/were-failing-to-solve-the-worlds-wicked-problems-heres-a-better-approach-64949">wicked problem</a>. Many factors <a href="https://hbr.org/2018/10/why-people-arent-motivated-to-address-climate-change">combine to make it harder</a> for us to act. </p>
<p>The necessary policies and behaviour changes have been viewed as too hard or costly. Until recently, the consequences of doing nothing have been seen as a distant problem. Given the complexity of climate modelling, it has been difficult for scientists and policymakers to lay out what the specific environmental consequences would be from any given action or when they would manifest. </p>
<p>As if that’s not enough, climate change presents a collective-action problem. It would do little good for Australia to reach net-zero emissions if other countries keep emitting without change. </p>
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Read more:
<a href="https://theconversation.com/inside-the-mind-of-a-sceptic-the-mental-gymnastics-of-climate-change-denial-189645">Inside the mind of a sceptic: the ‘mental gymnastics’ of climate change denial</a>
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<p>When we write about climate change, we often frame it as an ever more urgent and significant threat to our way of life. We do this thinking that showing the seriousness of the threat will galvanise others into faster action. </p>
<p>Unfortunately, this isn’t always the case. When we’re confronted with big risks – and the need for a painful shift from the status quo – some of us respond unexpectedly. We might find ourselves motivated to seek out evidence to undercut the reality of the threat, and use this uncertainty to justify staying on the same path. </p>
<p>One unfortunate aspect of this is that people motivated to avoid or deny climate risk are actually better able to do so when they have more scientific training. This background equips them better to <a href="https://www.nature.com/articles/nclimate1547">counter-argue and rationalise the dissonance</a>, meaning they seek out information to align with their beliefs and justify their passivity. Misinformation and doubt are particularly damaging to climate action. They let us feel OK about inaction. </p>
<p>This tendency to rationalise away risk was also clearly visible among people who <a href="https://wires.onlinelibrary.wiley.com/doi/abs/10.1002/wcc.837">downplayed the impact or even denied the existence of COVID-19</a>. </p>
<p>Is there an antidote?</p>
<p>We’ve found explaining the <a href="https://academic.oup.com/poq/article-abstract/84/1/74/5860243">simple and well-understood way</a> that emissions of specific gases trap the Sun’s heat and warm the planet can be effective, because people can’t rationalise these facts away. The greenhouse effect is a well-accepted phenomenon, even by those most sceptical of global warming. After all, it’s essential to life on Earth – without these gases trapping heat, the world would be too cold for life.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/557063/original/file-20231101-23-pjqp9u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="a greenhouse with lettuces growing" src="https://images.theconversation.com/files/557063/original/file-20231101-23-pjqp9u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/557063/original/file-20231101-23-pjqp9u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=436&fit=crop&dpr=1 600w, https://images.theconversation.com/files/557063/original/file-20231101-23-pjqp9u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=436&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/557063/original/file-20231101-23-pjqp9u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=436&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/557063/original/file-20231101-23-pjqp9u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=548&fit=crop&dpr=1 754w, https://images.theconversation.com/files/557063/original/file-20231101-23-pjqp9u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=548&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/557063/original/file-20231101-23-pjqp9u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=548&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 greenhouse effect is well known and uncontroversial.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>Why are we finally acting?</h2>
<p>As climate change has moved out of the computer models and become very much a part of our present, we are seeing stronger efforts to cut emissions.</p>
<p>More and more of us are experiencing tangible events such as forest fires, droughts, sudden floods, rapidly intensifying hurricanes or record-breaking heatwaves. This has removed one barrier to inaction. Until now, the consequences of doing nothing seemed far off and uncertain. Now they are seen as certain and already present. </p>
<p>Better still, technological advancement and economies of scale in production have meant clean energy and clean transport have fallen significantly in price. </p>
<p>At government and individual levels, there are now measures we can take that aren’t too costly and come with immediate gains such as cutting power bills or avoiding petrol price increases. Greater political consensus in many countries is also helping challenge the inertia of the status quo. That’s another barrier to action evaporating. </p>
<p>As climate damage gets worse, we’re likely to see <a href="https://www.washingtonpost.com/climate-environment/2023/10/30/climate-emergency-scientists-declaration/?pwapi_token=eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJyZWFzb24iOiJnaWZ0IiwibmJmIjoxNjk4NjM4NDAwLCJpc3MiOiJzdWJzY3JpcHRpb25zIiwiZXhwIjoxNzAwMDI0Mzk5LCJpYXQiOjE2OTg2Mzg0MDAsImp0aSI6IjUxNTg2NGViLWU2ODEtNGRiZS1iNmRiLTU5ZjI0ODZhNjc3ZCIsInVybCI6Imh0dHBzOi8vd3d3Lndhc2hpbmd0b25wb3N0LmNvbS9jbGltYXRlLWVudmlyb25tZW50LzIwMjMvMTAvMzAvY2xpbWF0ZS1lbWVyZ2VuY3ktc2NpZW50aXN0cy1kZWNsYXJhdGlvbi8ifQ.n_OHYGJLLYGR7XJbSSGh8mGOTiqMYBjwOeig4lTX8uc">ever-starker warnings</a>. Does fear motivate us? When faced with threats, we are more <a href="https://psycnet.apa.org/record/2015-48611-002">likely to take action</a>, particularly if we think we can make a difference. </p>
<p>Yes, we now have a very narrow window to avert the worst. But we also have an increased certainty about climate change and the damage it causes, as well as greater confidence in our ability to bring about change. </p>
<p>For years, our own psychology slowed down efforts to make the sweeping changes necessary to quit fossil fuels. Now, at least, some of these psychological barriers are getting smaller. </p>
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Read more:
<a href="https://theconversation.com/most-people-already-think-climate-change-is-here-and-now-despite-what-weve-been-told-203425">Most people already think climate change is 'here and now', despite what we've been told</a>
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<p class="fine-print"><em><span>Jeff Rotman has received funding from the Australian Energy Market Operator, Mondo Power, and iMove Australia</span></em></p>One barrier to climate action has been our own psychology and reluctance to take action. But as the crisis intensifies, some of these barriers have evaporated.Jeff Rotman, Senior Lecturer in Marketing and Consumer Psychology & Co-Director of the Better Consumption Lab, Deakin UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2106552023-09-03T07:46:09Z2023-09-03T07:46:09ZZimbabwe’s climate action plan: a win for the environment, health and energy<figure><img src="https://images.theconversation.com/files/545067/original/file-20230828-26-s7ub5a.jpg?ixlib=rb-1.1.0&rect=44%2C0%2C5000%2C3263&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Reducing carbon emissions will promote health and development in Zimbabwe. Zinyange Auntony/ AFP/</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/school-children-ride-bicycles-through-a-forest-to-school-on-news-photo/1258934871?adppopup=true">Getty Images</a></span></figcaption></figure><p>The dumping of billions of tonnes of carbon dioxide and other <a href="https://www.unep.org/resources/emissions-gap-report-2022">greenhouse gases</a> into the atmosphere yearly is already having a devastating impact around the world. This includes <a href="https://report.ipcc.ch/ar6/wg2/IPCC_AR6_WGII_FullReport.pdf#page=140">widespread flooding and droughts, raging wildfires, heatwaves and record temperatures</a>.</p>
<p><a href="https://library.wmo.int/index.php?lvl=notice_display&id=22125">Africa</a> is particularly hard hit, with temperatures and sea levels rising faster across the continent than the global average. </p>
<p>In Zimbabwe, unreliable rainfalls and extended droughts are affecting <a href="https://www.science.org/content/article/zimbabwe-drought-driving-hydropower-crisis-and-search-alternatives">hydro electricity generation, resulting in rolling blackouts</a>. Food production is also affected. A <a href="https://www.wfp.org/stories/how-drought-killing-zimbabwe">large fraction of Zimbabwe’s population is at risk of severe hunger</a>.</p>
<p>In 2015, almost all countries signed the <a href="https://unfccc.int/sites/default/files/english_paris_agreement.pdf">Paris Agreement</a>, a commitment to tackle climate change. The intention was to limit global temperature increase to below 2°C, or ideally 1.5°C. To achieve this, countries submitted individual plans, called Nationally Determined Contributions, to reduce their contribution to climate change. They agreed to update them every five years.</p>
<p>The continent of Africa <a href="https://library.wmo.int/index.php?lvl=notice_display&id=22125">contributes 2%-3%</a> of the global greenhouse gas emissions causing climate change. Zimbabwe <a href="https://www.sciencedirect.com/science/article/pii/S221146452300091X">contributes less than 0.1%</a>. Despite this small contribution, all African countries submitted their plans to reduce emissions. </p>
<p>In 2015, Zimbabwe committed to <a href="https://unfccc.int/NDCREG">reducing its emissions</a> by 33% by 2030. In 2021, it <a href="https://climatepromise.undp.org/what-we-do/where-we-work/zimbabwe">updated</a> the target to a 40% reduction by 2030 across all sectors. This significant improvement increases the fraction of emissions that Zimbabwe will reduce from all emitting sectors. </p>
<p>The energy sector is <a href="https://www.sciencedirect.com/science/article/pii/S221146452300091X">responsible for about 34%</a> of Zimbabwe’s total emissions. Including other sectors, like agriculture and forestry (58% of total emissions), waste (5%) and industrial processes (3%) will substantially reduce greenhouse gas emissions if Zimbabwe achieves its target. </p>
<h2>How Zimbabwe can meet its emission reduction target</h2>
<p>The updated target was informed by an assessment of how greenhouse gas emission could be reduced. The assessment was done by a team of researchers from Zimbabwe and the Stockholm Environment Institute at the University of York (including myself). It provided a clear plan to achieve the targets through the implementation of <a href="https://www.sciencedirect.com/science/article/pii/S221146452300091X">28 specific policies and measures</a>. </p>
<p>We assessed the benefits of these actions to mitigate climate change. We also reviewed other implications of taking each action locally in Zimbabwe. </p>
<p><a href="https://www.sciencedirect.com/science/article/pii/S221146452300091X">Our research</a> showed that by implementing its climate change plan, Zimbabwe would not only meet its international obligations, but achieve a broad set of health, social and development benefits. </p>
<p>The study assessed and quantified how the 28 actions to achieve Zimbabwe’s climate change plan would contribute to specific <a href="https://sdgs.un.org/goals">Sustainable Development Goals</a>. </p>
<p>The top three benefits identified were improved public health, enhanced biodiversity, and greater access to reliable energy supplies. Each of these benefits is a priority within <a href="https://zimbabwe.un.org/en/153007-2021-2025-national-development-strategy-nds-i">Zimbabwe’s National Development Strategy 1 2021-2025</a>. </p>
<p>Good health is a constitutional right in Zimbabwe. Air pollution and unsafe sanitation are among the top 10 <a href="https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(20)30752-2/fulltext">risk factors for health</a> in Zimbabwe, and can be reduced by carrying out Zimbabwe’s climate change plan. </p>
<p>Reducing biodiversity losses will not only address an environmental challenge in Zimbabwe’s National Development Strategy, but preserve and enhance the tourism industry. </p>
<p>After years of unreliable energy supplies due to drought, and reliance on biomass fuels for cooking for much of the population, providing <a href="https://www.zera.co.zw/National_Renewable_Energy_Policy_Final.pdf#page=9">regular and reliable energy supplies</a> is critical for alleviating poverty and economic growth. </p>
<h2>Counting the benefits</h2>
<p><strong>Public health:</strong> Currently, almost 6,000 infants and over 8,000 adults <a href="https://www.sciencedirect.com/science/article/pii/S221146452300091X">die</a> yearly from air pollution in Zimbabwe. Almost 1,600 people die from road traffic accidents, and 337 people <a href="https://www.sciencedirect.com/science/article/pii/S221146452300091X">die</a> from unsafe sanitation. The study estimates that actions reducing greenhouse gases would also reduce air pollutant emissions by between 35% and 45% by 2030. This would lead to lower air pollution exposure, especially indoors where women and girls are most exposed while cooking.</p>
<p>Cleaner energy for cooking, improved transport systems and improved waste management all reduce air pollution. Increasing the use of public transport, or walking and cycling, rather than using cars can reduce road accidents and greenhouse gas emissions from transport. </p>
<p>Expanding access to sanitation systems would reduce the number of people dying from diarrhoeal diseases, and reduce methane emissions if the correct systems were installed.</p>
<p><strong>Improved biodiversity:</strong> Zimbabwe’s climate change actions also include changes to how land is used. It aims to <a href="http://www.envirotourism.org.zw/wp-content/uploads/2017/08/Zimbabwe-Revised-Nationally-Determined-Contribution-2021-Final-1.pdf#page=36">reduce burned areas of forest by 500,000 hectares and add 100,000 hectares</a> of natural forest every year to 2025. The plan would also manage 250,000 more hectares of cropland using sustainable “conservation agriculture” techniques. </p>
<p>These actions were estimated to achieve multiple benefits, including improving soil health and protecting biodiversity, with possible reduction in the losses of both animals and plants.</p>
<p><strong>Access to reliable energy:</strong> Achieving Zimbabwe’s climate change plan is <a href="https://www.sciencedirect.com/science/article/pii/S221146452300091X">built</a> on extending electricity access to 95% of urban households and 75% of rural households. Actions in the plan include the expansion of renewable electricity generation, energy efficiency improvements, and reducing losses from electricity transmission and distribution. These steps can help ensure that access to energy is quick and effective, thereby reducing blackouts and reliance on fossil fuels. </p>
<p>In addition, the study shows that Zimbabwe could increase recycling rates while reducing emissions from waste. The country can equally reduce the time people – predominantly women and girls – spend cooking by switching to cleaner cooking fuels.</p>
<h2>More than a sacrifice</h2>
<p>Tackling climate change is often viewed as a necessary sacrifice, rather than an opportunity to improve lives. </p>
<p>Climate change targets are often focused solely on how they contribute to global, long-term aspirations, rather than the benefits that countries can achieve in the short term.</p>
<p>Our study shows the social, health and development benefits that Zimbabwe could enjoy by tackling its (small) contribution to climate change. This is not unique to Zimbabwe, nor a full list of all possible <a href="https://www.nature.com/articles/s41558-017-0012-x">benefits</a> from climate change action.</p>
<p>What is notable about the Zimbabwe study is that these local benefits were evaluated and quantified, alongside greenhouse gas emission reductions. They provide a positive case of what countries can gain from taking climate action. </p>
<p>Integrating quantitative assessment of local benefits when countries develop their climate change plans, following Zimbabwe’s example, could help boost national climate plans. This would in turn help the world meet necessary emission reduction timelines and avoid the worst impacts.</p><img src="https://counter.theconversation.com/content/210655/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Chris Malley receives funding from the United Nations Environment Programme, and UK Research & Innovation, . </span></em></p>Zimbabwe’s climate action plan is on track to check emissions and promote development. Other countries can learn from it.Chris Malley, Research Fellow, Stockholm Environment Institute York Centre, University of YorkLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2106612023-08-15T21:45:18Z2023-08-15T21:45:18ZHow our complex relationship with heat inhibits climate action<figure><img src="https://images.theconversation.com/files/542843/original/file-20230815-19-xfrs03.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C5607%2C3732&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The heat is preferred by many, and such preferences have hampered effective climate change communications.</span> <span class="attribution"><span class="source">(AP Photo/Petros Giannakouris)</span></span></figcaption></figure><iframe style="width: 100%; height: 100px; border: none; position: relative; z-index: 1;" allowtransparency="" allow="clipboard-read; clipboard-write" src="https://narrations.ad-auris.com/widget/the-conversation-canada/how-our-complex-relationship-with-heat-inhibits-climate-action" width="100%" height="400"></iframe>
<p>Humans are a <a href="https://doi.org/10.1073/pnas.1001824107">species borne of the heat, as hot and dry temperatures played a key role in our evolution</a>, and <a href="https://www.newswire.ca/news-releases/survey-says-half-of-canadians-take-a-beach-holiday-to-leave-behind-the-winter-blues-while-others-do-so-to-relax-and-forget-a-regular-routine-670876433.html">many of us in Canada seemingly prefer to be in warm places</a>.</p>
<p>We as a species have known for decades that the carbon-fuelled actions of some nations meant that devastating heat and related extreme weather events were coming.</p>
<p>And yet, most of us did nothing.</p>
<p>The summer of 2023’s <a href="https://www.nytimes.com/interactive/2023/08/03/climate/ocean-temperatures-heat-earth.html">unprecedented forest fires, floods and rising ocean temperatures</a> are the consequences of collective inaction and while there are many reasons for these failures to act, humanity’s complex relationship with heat is arguably a critical one.</p>
<h2>The comfort, and dangers, of heat</h2>
<p>At a fundamental level, heat is what allows for humans and the Earth’s biological diversity to exist. A stable core body temperature facilitates human survival and the <a href="https://www.bgs.ac.uk/discovering-geology/climate-change/how-does-the-greenhouse-effect-work/">greenhouse effect facilitates all life on Earth</a>. However, while heat may be essential to life, and desirable to many, <a href="https://climate.nasa.gov/news/2865/a-degree-of-concern-why-global-temperatures-matter/">too much heat is devastating</a>.</p>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/a-quick-guide-to-climate-change-jargon-what-experts-mean-by-mitigation-carbon-neutral-and-6-other-key-terms-167172">A quick guide to climate change jargon – what experts mean by mitigation, carbon neutral and 6 other key terms</a>
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<p>One <a href="https://www.nytimes.com/2023/03/21/briefing/climate-report.html">way to articulate this complex balance has been to use the metaphor of a fever</a>. If a human’s body temperature increases even a couple of degrees, then an illness is likely occurring. If a person’s core body temperature increases only three to four degrees celsius it can be fatal. Likewise, a rise in planetary temperatures above just 1.5 C could be equally fatal.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/542842/original/file-20230815-26-m6i6me.gif?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/542842/original/file-20230815-26-m6i6me.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/542842/original/file-20230815-26-m6i6me.gif?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/542842/original/file-20230815-26-m6i6me.gif?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/542842/original/file-20230815-26-m6i6me.gif?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/542842/original/file-20230815-26-m6i6me.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/542842/original/file-20230815-26-m6i6me.gif?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/542842/original/file-20230815-26-m6i6me.gif?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">An animated overview of the basic principles of the greenhouse effect. While the term greenhouse effect may be useful in some cases, it is generally inaccurate when referring to anthropogenic climate change.</span>
<span class="attribution"><span class="source">(NASA-JPL/Caltech)</span></span>
</figcaption>
</figure>
<p>A seemingly easy to understand threshold. However, in practice, communicating a 1.5 C tipping point has been extremely challenging. Humans generally <a href="https://www.bbc.com/future/article/20190304-human-evolution-means-we-can-tackle-climate-change">struggle with disentangling short-term daily temperatures from a long-term climatic shift</a> and as a result <a href="https://www.nationalgeographic.com/environment/article/climate-change-colder-winters-global-warming-polar-vortex">fluctuations in temperature have been easily misunderstood</a>. And confusion over these questions are <a href="https://www.motherjones.com/environment/2016/12/trump-climate-timeline/">readily misused to question the veracity of an anthropogenically induced changing climate.</a></p>
<h2>All under one greenhouse?</h2>
<p>An early attempt at circumventing our innate fondness for heat in climate change communications was through leveraging the term <em>greenhouse effect</em> — a phrase which notably removes heat from the equation altogether.</p>
<p>Knowledge of the greenhouse effect goes back to the mid-19th century. In the latter half of the 20th century, the term <a href="https://www.ipcc.ch/site/assets/uploads/2018/03/ar4-wg1-chapter1.pdf">became an evocative label for what the burning of fossil fuels was doing to the planet</a>.</p>
<p>But the term is inaccurate. </p>
<p>The greenhouse effect is the well-established phenomenon of the Earth’s atmosphere trapping the sun’s radiation and allowing the planet to be a warm and hospitable place. Using the greenhouse effect as a term referring to the warming of the planet due to the burning of fossil fuels <a href="https://doi.org/10.22230/cjc.2008v33n2a2017">conflated a naturally occurring and well-established phenomenon with an unfolding anthropogenic disaster to confusing results</a>.</p>
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Read more:
<a href="https://theconversation.com/how-language-can-turn-down-the-temperature-of-heated-climate-change-discourse-210865">How language can turn down the temperature of heated climate change discourse</a>
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<p>In response to this limitation, <em>global warming</em> increasingly became the terminology of choice for the changing climate — <a href="https://gpm.nasa.gov/education/articles/whats-name-global-warming-vs-climate-change/">phasing out the banal <em>inadvertent climate modification</em> which had also been in use since the 1970s</a>. So much so that by the 1990s, <a href="https://doi.org/10.22230/cjc.2008v33n2a2017">it became the single most used term</a>. But this also had challenges. </p>
<p>Warming has a certain coziness and as climate change researchers Julia Corbett and Jessica Durfee highlighted, ‘<a href="https://niemanreports.org/articles/context-and-controversy-global-warming-coverage/">global warming needs a more salient metaphor that emphasizes its seriousness, immediacy and scientific credibility</a>.’</p>
<figure class="align-center ">
<img alt="London Mayor Sadiq Khan and King Charles III stand at a podium on stage." src="https://images.theconversation.com/files/542840/original/file-20230815-31-szpp0k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/542840/original/file-20230815-31-szpp0k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=390&fit=crop&dpr=1 600w, https://images.theconversation.com/files/542840/original/file-20230815-31-szpp0k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=390&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/542840/original/file-20230815-31-szpp0k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=390&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/542840/original/file-20230815-31-szpp0k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=490&fit=crop&dpr=1 754w, https://images.theconversation.com/files/542840/original/file-20230815-31-szpp0k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=490&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/542840/original/file-20230815-31-szpp0k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=490&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The term global warming (seen here in use at an event in London) is provocative but also inaccurate and potentially counter-productive.</span>
<span class="attribution"><span class="source">(Justin Tallis via AP)</span></span>
</figcaption>
</figure>
<p>Global warming was also a narrow term, <a href="https://www.nasa.gov/feature/warming-makes-droughts-extreme-wet-events-more-frequent-intense">as global average temperature increases would cause a range of extreme weather effects</a></p>
<p>In response to these limitations, the term climate change gradually came to replace global warming as the most widely accepted and used descriptor. Though more recently, this somewhat benign term has been altered again by some to more accurately address the urgency of the situation. </p>
<p>For example, in 2019 The Guardian moved from using <em>climate change</em> to the terms <a href="https://www.theguardian.com/environment/2019/may/17/why-the-guardian-is-changing-the-language-it-uses-about-the-environment"><em>climate emergency</em>, <em>crisis or breakdown</em></a> in response to climatic effects of ever-increasing severity.</p>
<p>This <a href="https://www.brookings.edu/articles/climate-confusion-content-and-strategies-not-controversy-are-the-biggest-challenges-for-science-teachers/">confused discourse has led to even further confusion</a> and arguably hampered climate change mitigation efforts for decades. </p>
<h2>Too much of a good thing</h2>
<p>Research indicates that in the summer of 2022, over <a href="https://www.nature.com/articles/s41591-023-02419-z">60,000 people in Europe alone died from extreme heat</a>. <a href="https://www.theguardian.com/environment/2023/aug/08/july-2023-worlds-hottest-month-climate-crisis-scientists-confirm">July 2023 was the hottest month ever recorded</a> and it is <a href="https://www.carbonbrief.org/state-of-the-climate-2023-now-likely-hottest-year-on-record-after-extreme-summer/">increasingly looking like 2023 will be the hottest year on record</a>. Heat-related <a href="https://yaleclimateconnections.org/2023/07/the-scorching-summer-of-2023-reaches-mind-blowing-high-temperatures/">deaths are mounting</a> and the heat is <a href="https://montrealgazette.com/news/quebec/climate-change-is-exacerbating-forest-fires-and-vice-versa-experts-say">being exacerbated by raging fires</a> and <a href="https://www.theguardian.com/environment/2023/aug/04/oceans-hit-highest-ever-recorded-temperature">extreme ocean temperatures</a>.</p>
<figure class="align-right ">
<img alt="Map showing extent and distribution of wild fires in Hawaii" src="https://images.theconversation.com/files/542838/original/file-20230815-25-tqjzv2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/542838/original/file-20230815-25-tqjzv2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/542838/original/file-20230815-25-tqjzv2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/542838/original/file-20230815-25-tqjzv2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/542838/original/file-20230815-25-tqjzv2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/542838/original/file-20230815-25-tqjzv2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/542838/original/file-20230815-25-tqjzv2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The recent wildfires in Hawaii further underline the importance of addressing our planetary over-consumption and fossil fuel use.</span>
<span class="attribution"><span class="source">(NOAA via AP)</span></span>
</figcaption>
</figure>
<p>Human beings, alongside all life, exist on Earth because of a <a href="https://climate.nasa.gov/faq/19/what-is-the-greenhouse-effect/">delicate celestial balance of gasses that trap the sun’s warmth</a>. For millions of years, this greenhouse effect has made Earth a miraculously habitable orb in the coldness of space.</p>
<p>While all human beings have a complex — and often positive — relationship with heat, <a href="https://www.pewresearch.org/social-trends/2009/03/18/most-like-it-hot/">in the Northern Hemisphere it is something which many of us particularly crave</a>. However, the reckless pursuit of it (among other comforts) through the burning of fossil fuels has turned heat from a source of life to a harbinger of doom for all. </p>
<p>It is only through confronting this complex relationship — by accepting the inherent dangers of <em>more</em> heat — that we can hope to seriously pursue real action on fossil fuel emissions.</p><img src="https://counter.theconversation.com/content/210661/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jennifer Ellen Good 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>Humans (particularly those in the Northern Hemisphere) generally prefer the heat, a bias which has hampered effective climate communications for decades.Jennifer Ellen Good, Associate Professor Communication, Popular Culture and Film, Brock UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2026192023-05-02T20:00:35Z2023-05-02T20:00:35ZTwo trillion tonnes of greenhouse gases, 25 billion nukes of heat: are we pushing Earth out of the Goldilocks zone?<figure><img src="https://images.theconversation.com/files/518313/original/file-20230329-18-i75ehz.jpg?ixlib=rb-1.1.0&rect=58%2C58%2C5482%2C3547&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>Since the 18th century, humans have been taking fossil fuels out of their safe storage deep underground and burning them to generate electricity or power machinery. </p>
<p>We’ve now converted coal, oil and gas into more than two trillion tonnes of heat-trapping carbon dioxide and other greenhouse gases and added them to the atmosphere.</p>
<p>The current result? The average temperature at the planet’s surface is about 1.2°C hotter than in the pre-industrial era. That’s because <a href="https://theconversation.com/a-tonne-of-fossil-carbon-isnt-the-same-as-a-tonne-of-new-trees-why-offsets-cant-save-us-200901">adding new carbon</a> to the world’s natural carbon cycle has caused an imbalance in the amount of energy entering and leaving the Earth system.</p>
<p>To warm the entire planet takes an extraordinary amount of extra energy. <a href="https://essd.copernicus.org/articles/15/1675/2023/">Recent research</a> shows we’ve added the energy of 25 billion nuclear bombs to the Earth system in just the last 50 years. </p>
<p>Billions of nuclear bombs to produce 1.2°C of heating – so what? It seems small, considering how much temperature varies on a daily basis. (The world’s average surface temperature in the 20th century was 13.9°C.)</p>
<p>But almost all of this energy to date has been taken up by the oceans. It’s no wonder we’re seeing <a href="https://theconversation.com/in-hot-water-heres-why-ocean-temperatures-are-the-hottest-on-record-204534">rapid warming</a> in our oceans. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/523713/original/file-20230502-22-ieb7so.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="earth from space" src="https://images.theconversation.com/files/523713/original/file-20230502-22-ieb7so.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/523713/original/file-20230502-22-ieb7so.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/523713/original/file-20230502-22-ieb7so.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/523713/original/file-20230502-22-ieb7so.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/523713/original/file-20230502-22-ieb7so.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=565&fit=crop&dpr=1 754w, https://images.theconversation.com/files/523713/original/file-20230502-22-ieb7so.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=565&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/523713/original/file-20230502-22-ieb7so.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=565&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Life on Earth is possible because we’re in a sweet spot – not too hot, not too cold.</span>
<span class="attribution"><span class="source">NASA</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>The Goldilocks zone</h2>
<p>Mercury is the closest planet to the Sun. It gets hot, at an average temperature of 167°C. But it has no atmosphere. That’s why the second planet, Venus, is <a href="https://solarsystem.nasa.gov/resources/681/solar-system-temperatures/">the hottest</a> in the solar system, at an average of 464°C. That’s due to an atmosphere much thicker than Earth’s, dense in carbon dioxide. Venus might once have had liquid oceans. But then a runaway greenhouse effect took place, trapping truly enormous quantities of heat.</p>
<p>One reason we’re alive is that our planet orbits in the <a href="https://exoplanets.nasa.gov/faq/15/what-is-the-habitable-zone-or-goldilocks-zone/#:%7E:text=The%20distance%20Earth%20orbits%20the,liquid%20water%20on%20their%20surfaces.">Goldilocks zone</a>, just the right distance from the Sun to be not too hot and not too cold. Little of the Earth’s internal heat gets through to the cold crust where we live. That makes us dependent on another source of heat – the Sun. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/global-carbon-emissions-at-record-levels-with-no-signs-of-shrinking-new-data-shows-humanity-has-a-monumental-task-ahead-193108">Global carbon emissions at record levels with no signs of shrinking, new data shows. Humanity has a monumental task ahead</a>
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<p>When the Sun’s light and heat hits Earth, some is absorbed at the surface and some is reflected back out into space. We see some of the energy emitted by the Sun because the Sun is hot and hotter objects emit radiation in the visible part of the electromagnetic spectrum.</p>
<p>Because Earth is much cooler than the Sun, the radiation it emits is invisible, at long infrared wavelengths. Much of this energy goes out into space – but not all. Some gases in our atmosphere are very effective at absorbing energy at the wavelengths Earth emits at. These greenhouse gases occur naturally in Earth’s atmosphere, and keep the planet warm enough to be habitable. That’s another Goldilocks zone.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/517582/original/file-20230327-22-73myrj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Earth energy budget" src="https://images.theconversation.com/files/517582/original/file-20230327-22-73myrj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/517582/original/file-20230327-22-73myrj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=448&fit=crop&dpr=1 600w, https://images.theconversation.com/files/517582/original/file-20230327-22-73myrj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=448&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/517582/original/file-20230327-22-73myrj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=448&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/517582/original/file-20230327-22-73myrj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=563&fit=crop&dpr=1 754w, https://images.theconversation.com/files/517582/original/file-20230327-22-73myrj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=563&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/517582/original/file-20230327-22-73myrj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=563&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Incoming radiation from the sun is reflected or absorbed by Earth. There is a net imbalance where more energy is absorbed than emitted by the planet and this causes warming.</span>
<span class="attribution"><span class="source">NASA</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>And then there’s a third Goldilocks zone: recent history. All of human civilisation has emerged in the unusually mild 10,000 years after the last ice age, when the climate has been not too hot and not too cold across much of the world. </p>
<p>But now, we are at very real risk of pushing ourselves outside of the comfortable climatic conditions which allowed humans to expand, farm, build cities and create.</p>
<p>The energy dense fuels which made industrial civilisation possible come with an enormous sting in the tail. Burn now, pay later. Now the bill has become apparent. </p>
<p>How do we know this is real? Satellites measure the rate at which Earth’s surface radiates heat. At any one moment, thousands of <a href="https://argo.ucsd.edu/">Argo robotic floats</a> dot our oceans. They spend almost all of their lives underwater, measuring heat, and surface to transmit data. And we can measure sea level with tide levels and satellites. We can cross-check the measurements between all three approaches. </p>
<h2>Climate change: more energy comes in than goes out</h2>
<p>Greenhouse gases are potent. You only need small concentrations to get a big effect. </p>
<p>We’ve already boosted the amount of carbon dioxide in the atmosphere by about 50%, and added considerable volumes of methane and nitrous oxide as well. This is pushing our life-sustaining greenhouse effect out of balance. </p>
<p>A recent <a href="https://essd.copernicus.org/articles/15/1675/2023/">study</a> suggests the energy imbalance is equivalent to trapping roughly 380 zettajoules of extra heat from 1971–2020. (The period between 1971 and the present <a href="https://news.sky.com/story/climate-change-how-much-carbon-dioxide-has-been-produced-since-you-were-born-enter-your-year-of-birth-to-find-out-12415233">accounts for</a> about 60% of all emissions).</p>
<p>One zettajoule is 1,000,000,000,000,000,000,000 joules – a very big number! </p>
<p>Little Boy, the nuclear bomb which destroyed Hiroshima, produced energy estimated at 15,000,000,000,000 joules. This means the effect of humanity’s greenhouse gas emissions in that 50-year period to 2020 is about 25 billion times the energy emitted by the Hiroshima nuclear bomb. </p>
<h2>If we’ve trapped so much extra heat, where is it?</h2>
<p>To date, almost every joule of extra energy – about 90% – has gone into our oceans, particularly the top kilometre of water. Water is an excellent heat sink. It takes a lot of energy to heat it, but heat it we have. Hotter oceans are a major contributor to coral bleaching and sea level rise. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/523715/original/file-20230502-22-j8ayb1.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="sea surface temperature" src="https://images.theconversation.com/files/523715/original/file-20230502-22-j8ayb1.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/523715/original/file-20230502-22-j8ayb1.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=364&fit=crop&dpr=1 600w, https://images.theconversation.com/files/523715/original/file-20230502-22-j8ayb1.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=364&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/523715/original/file-20230502-22-j8ayb1.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=364&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/523715/original/file-20230502-22-j8ayb1.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=458&fit=crop&dpr=1 754w, https://images.theconversation.com/files/523715/original/file-20230502-22-j8ayb1.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=458&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/523715/original/file-20230502-22-j8ayb1.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=458&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’s the heat? In our oceans. This sea surface temperature map shows the temperature anomalies above or below the long term average at 30th April 2023.</span>
<span class="attribution"><a class="source" href="https://www.ospo.noaa.gov/Products/ocean/sst/anomaly/">NOAA</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>It takes a long time to get this much heat into the oceans, and once it is there it doesn’t disappear. Reversing global warming entirely may not be feasible. Just to stop temperatures going any higher means correcting the imbalance and bringing CO2 levels down towards the pre-industrial level of 280ppm. </p>
<p>If we can reach net-zero greenhouse gas emissions, we will most likely stop further global warming and carbon dioxide concentrations will slowly start to drop. </p>
<p>Realistically, this means rapid, large-scale reduction of emissions and deployment of carbon capture to compensate for the emissions we can’t eliminate.</p>
<p>To go further and cool the planet back down towards a pre-industrial climate would require net-negative emissions, meaning we would have to draw even more carbon back out of the atmosphere than any lingering emissions. </p>
<p>Unfortunately, we aren’t there yet. Human-caused greenhouse gas emissions are at <a href="https://theconversation.com/global-carbon-emissions-at-record-levels-with-no-signs-of-shrinking-new-data-shows-humanity-has-a-monumental-task-ahead-193108">near-record highs</a>. But clean energy production <a href="https://ourworldindata.org/renewable-energy">is accelerating</a>. This year <a href="https://www.bbc.com/news/science-environment-65240094">might be</a> the first time emissions from power begin to fall. </p>
<p>We’re in a race, and the stakes are as high as they could possibly be – ensuring a liveable climate for our children and for nature. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/in-hot-water-heres-why-ocean-temperatures-are-the-hottest-on-record-204534">In hot water: here's why ocean temperatures are the hottest on record</a>
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<img src="https://counter.theconversation.com/content/202619/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><p class="fine-print"><em><span>Steven Sherwood receives funding from the Australian Research Council</span></em></p>Life relies on a fine balance between energy in and energy out. But heating the world 1.2°C means we’ve trapped an extraordinary amount of extra energy in the Earth system.Andrew King, Senior Lecturer in Climate Science, The University of MelbourneSteven Sherwood, Professor of Atmospheric Sciences, Climate Change Research Centre, UNSW SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1877812022-08-11T20:05:02Z2022-08-11T20:05:02ZBeyond net-zero: we should, if we can, cool the planet back to pre-industrial levels<figure><img src="https://images.theconversation.com/files/478432/original/file-20220810-11-eziox2.jpg?ixlib=rb-1.1.0&rect=23%2C31%2C5303%2C3514&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Marc Pell/Unsplash</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>The world’s focus is sharply fixed on achieving <a href="https://climateactiontracker.org/methodology/net-zero-targets">net-zero emissions</a>, yet surprisingly little thought has been given to what comes afterwards. In our <a href="https://www.nature.com/articles/s41558-022-01446-x">new paper</a>, published today in Nature Climate Change, we discuss the big unknowns in a post net-zero world. </p>
<p>It’s vital that we understand the consequences of our choices when it comes to greenhouse gas emissions and what comes next. The pathways we choose before and after reaching global net-zero emissions might mean the difference between a planet that remains habitable and one where many parts become inhospitable. </p>
<p>At the moment, human activities have a warming effect on the planet. But achieving our climate policy goals would take humanity into the uncharted territory of being able to <em>cool</em> the planet.</p>
<p>Being able to cool the planet raises a number of questions. Principally, how fast would we want the planet to cool, and what global average temperature should we aim for?</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/global-emissions-almost-back-to-pre-pandemic-levels-after-unprecedented-drop-in-2020-new-analysis-shows-170866">Global emissions almost back to pre-pandemic levels after unprecedented drop in 2020, new analysis shows</a>
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<hr>
<h2>How are our emissions changing?</h2>
<p>Our collective greenhouse gas emissions have warmed the planet <a href="https://globalwarmingindex.org/">about 1.2°C</a>, relative to pre-industrial temperatures. In fact, despite all the talk about reducing emissions, global carbon dioxide emissions are <a href="https://theconversation.com/global-emissions-almost-back-to-pre-pandemic-levels-after-unprecedented-drop-in-2020-new-analysis-shows-170866">at near-record levels</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/477803/original/file-20220805-5530-kyf2wz.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/477803/original/file-20220805-5530-kyf2wz.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/477803/original/file-20220805-5530-kyf2wz.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=374&fit=crop&dpr=1 600w, https://images.theconversation.com/files/477803/original/file-20220805-5530-kyf2wz.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=374&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/477803/original/file-20220805-5530-kyf2wz.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=374&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/477803/original/file-20220805-5530-kyf2wz.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=470&fit=crop&dpr=1 754w, https://images.theconversation.com/files/477803/original/file-20220805-5530-kyf2wz.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=470&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/477803/original/file-20220805-5530-kyf2wz.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=470&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Emissions have rebounded following the reductions seen during the pandemic-induced lockdowns. Looking back further we can see that carbon dioxide emissions have roughly quadrupled since 1960.</span>
<span class="attribution"><span class="source">Global Carbon Project</span></span>
</figcaption>
</figure>
<p>Some countries have successfully reduced their greenhouse gas emissions in recent years, such as the United Kingdom which has <a href="https://www.carbonbrief.org/analysis-uk-is-now-halfway-to-meeting-its-net-zero-emissions-target/.">halved greenhouse gas emissions</a> relative to 1990.</p>
<p>There is also <a href="https://theconversation.com/the-new-global-methane-pledge-can-buy-time-while-the-world-drastically-reduces-fossil-fuel-use-171182">greater push</a> from major emitters such as the United States and the European Union – as well as <a href="https://theconversation.com/pacific-islands-are-back-on-the-map-and-climate-action-is-not-negotiable-for-would-be-allies-187086">countries that emit less</a> but already experience climate change impacts – to take stronger steps to limit the damage we are doing to the climate.</p>
<p>Reducing greenhouse gas emissions and reaching net-zero are humanity’s greatest challenges. As long as greenhouse gas emissions remain substantially above net-zero we will continue to warm the planet. </p>
<p>To be in line with the Paris Agreement goal of limiting global warming to well below 2°C above pre-industrial levels this century, we need to drastically reduce our emissions. </p>
<p>We also need to increase our uptake of carbon from the atmosphere through developing and implementing <a href="https://theconversation.com/on-top-of-drastic-emissions-cuts-ipcc-finds-large-scale-co-removal-from-air-will-be-essential-to-meeting-targets-180663">drawdown technology</a>. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/on-top-of-drastic-emissions-cuts-ipcc-finds-large-scale-co-removal-from-air-will-be-essential-to-meeting-targets-180663">On top of drastic emissions cuts, IPCC finds large-scale CO₂ removal from air will be "essential" to meeting targets</a>
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</em>
</p>
<hr>
<h2>What will come after net-zero?</h2>
<p>Net-zero emissions will be reached when humanity’s greenhouse gas emissions into the atmosphere are balanced by their removal from the atmosphere. We would likely need to reach global net-zero well within <a href="https://www.carbonbrief.org/analysis-do-cop26-promises-keep-global-warming-below-2c/">the next 50 years</a> to keep global warming well below 2°C. </p>
<p>If we achieve this, we could continue the process of decarbonisation to reach net-negative greenhouse gas emissions – where more of humanity’s greenhouse gas emissions are removed from the atmosphere than released into it. </p>
<p>This would need to be achieved through a combination of “negative emissions” <a href="https://theconversation.com/the-morrison-government-wants-to-suck-co-out-of-the-atmosphere-here-are-7-ways-to-do-it-144941">technologies</a>, likely including some not invented yet, and land use changes such as reforestation.</p>
<p>Continued net-negative emissions will cause the planet to cool as greenhouse gas concentrations in the atmosphere fall. This is because the greenhouse effect, where gases such as carbon dioxide absorb radiation from Earth and warm the atmosphere, would weaken.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-morrison-government-wants-to-suck-co-out-of-the-atmosphere-here-are-7-ways-to-do-it-144941">The Morrison government wants to suck CO₂ out of the atmosphere. Here are 7 ways to do it</a>
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<hr>
<p>Currently, there’s almost no focus from governments, or indeed scientists, on the consequences of meeting our policy goals and going beyond net-zero. But this would be a turning point as the world would begin to cool. </p>
<p>Land would cool faster than the ocean. Indeed, some people may experience substantial cooling over their lifetimes – an unfamiliar concept to grasp in our warming climate. </p>
<p>These changes would be accompanied by effects on weather extremes and impacts to weather and climate-sensitive industries. While there’s not much research on this yet, we could, for example, see shipping routes close up as ice regrows in polar regions.</p>
<p>In the long-term, the best <a href="https://arxiv.org/ftp/arxiv/papers/0804/0804.1126.pdf">target global temperature</a> for the planet might be something akin to a <a href="https://theconversation.com/what-is-a-pre-industrial-climate-and-why-does-it-matter-78601">pre-industrial climate</a>, with the human effect on Earth’s climate receding. </p>
<p>In <a href="https://www.nature.com/articles/s41558-022-01446-x">our paper</a> we call for a new set of climate model experiments that allow us to understand the range of possible future climates after net-zero.</p>
<p>Any decisions must be informed by an understanding of the consequences of different choices for a post net-zero climate. For example, competing interests between countries and industries may make global agreements more challenging in a post net-zero world. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/477804/original/file-20220805-20-n8f6xh.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/477804/original/file-20220805-20-n8f6xh.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/477804/original/file-20220805-20-n8f6xh.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=318&fit=crop&dpr=1 600w, https://images.theconversation.com/files/477804/original/file-20220805-20-n8f6xh.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=318&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/477804/original/file-20220805-20-n8f6xh.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=318&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/477804/original/file-20220805-20-n8f6xh.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=400&fit=crop&dpr=1 754w, https://images.theconversation.com/files/477804/original/file-20220805-20-n8f6xh.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=400&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/477804/original/file-20220805-20-n8f6xh.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=400&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 Earth has warmed to date but after achieving net-zero emissions it will cool. We need new climate model simulations to understand this. Observed global mean surface temperature (GMST) comes from the Berkeley Earth dataset. The red, orange and blue lines illustrate possible scenarios for a post net-zero climate for which we wish to understand the implications.</span>
<span class="attribution"><span class="source">Author provided</span></span>
</figcaption>
</figure>
<h2>Why does this matter now?</h2>
<p>Reading this article, you may feel we’re getting ahead of ourselves. After all, as highlighted, global greenhouse gas emissions remain at near-record highs.</p>
<p>A key factor that will affect the behaviour of the climate system after net-zero emissions would be the maximum level of global warming that we peak at. This is dictated by our current and near-future emissions. </p>
<p>If we fail to meet the Paris Agreement and peak global warming reaches 2°C or more, then future generations will endure the effects of higher sea levels and other possible <a href="https://www.carbonbrief.org/explainer-nine-tipping-points-that-could-be-triggered-by-climate-change/">disastrous climate changes</a> for many centuries to come. </p>
<p>Our understanding of post net-zero impacts of different peak levels of global warming is extremely limited.</p>
<p>Reducing greenhouse gas emissions through decarbonisation remains our key priority. The more we can suppress global warming by reaching net-zero emissions as early as possible, the more we limit potential disastrous effects and the need to cool the planet in a post net-zero world. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/climate-change-killed-40-million-australian-mangroves-in-2015-heres-why-theyll-probably-never-grow-back-166971">Climate change killed 40 million Australian mangroves in 2015. Here's why they'll probably never grow back</a>
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<img src="https://counter.theconversation.com/content/187781/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><p class="fine-print"><em><span>Celia McMichael receives funding from the Australian Research Council, the National Health and Medical Research Council, Australian Red Cross, and the World Health Organization. </span></em></p><p class="fine-print"><em><span>Kale Sniderman receives funding from the Australian Research Council</span></em></p><p class="fine-print"><em><span>Kathryn Bowen has received funding for climate and health research, policy advice and technical assistance from the National Health and Medical Research Council, Australian Department of Foreign Affairs and Trade, WHO, Asian Development Bank, UNDP, UNEP, USAID, GIZ, EU, Future Earth, City of Melbourne, Victorian Department of Health. She is affiliated with the Climate and Health Alliance as a member of the Advisory Board and sits on the Science Committee of the World Adaptation Science Program.</span></em></p><p class="fine-print"><em><span>Tilo Ziehn receives funding from the Australian Government under the National Environmental Science Program. </span></em></p><p class="fine-print"><em><span>Zebedee Nicholls receives funding from the European Union under the Horizon 2020 Program. He is also a co-founder of Climate Resource, which connects governments and businesses with the latest climate science.</span></em></p><p class="fine-print"><em><span>Harry McClelland and Jacqueline Peel 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>Our ability to cool the planet takes humanity into uncharted territory. In a new paper published today, researchers discuss the big unknowns in a post net-zero world.Andrew King, Senior Lecturer in Climate Science, The University of MelbourneCelia McMichael, Senior Lecturer in Geography, The University of MelbourneHarry McClelland, Lecturer in Geomicrobiology, The University of MelbourneJacqueline Peel, Director, Melbourne Climate Futures, The University of MelbourneKale Sniderman, Senior Research Fellow, The University of MelbourneKathryn Bowen, Professor - Environment, Climate and Global Health at Melbourne Climate Futures and Melbourne School of Population and Global Health, University of Melbourne, The University of MelbourneTilo Ziehn, Principal Research Scientist, CSIROZebedee Nicholls, Research Fellow at The International Institute for Applied Systems Analysis (IIASA) and Melbourne Climate Futures, The University of MelbourneLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1829952022-05-23T19:52:18Z2022-05-23T19:52:18ZOther casualties of Putin’s war in Ukraine: Russia’s climate goals and science<p>As the European Union moves closer to an <a href="https://theconversation.com/europe-is-determined-to-cut-fossil-fuel-ties-with-russia-even-though-getting-hungary-on-board-wont-be-easy-182502">embargo deal on Russian oil</a>, there is much talk about the impact of war-related sanctions on <a href="https://www.theguardian.com/environment/2022/may/18/eu-plans-massive-increase-in-green-energy-to-rid-itself-of-reliance-on-russia">Europe’s energy transition</a> and the world’s <a href="https://www.eenews.net/articles/will-the-russian-invasion-accelerate-peak-oil/">decarbonisation efforts</a>.</p>
<p>But the sanctions also have strong implications for Russia’s already slow and rather unsure green transition, be it the modernisation of its energy sector or climate science. What Russia does or does not do matters for the rest of us: the world’s eleventh-largest economy also happens to be the <a href="https://edgar.jrc.ec.europa.eu/report_2021">fourth-largest emitter of greenhouse gases</a>, the <a href="https://www.iea.org/reports/russian-supplies-to-global-energy-markets/oil-market-and-russian-supply-2">second-largest crude oil exporter</a>, and the world’s <a href="https://www.iea.org/countries/russia">largest gas exporter</a>. The Russian economy is strongly dependent on the exploitation of energy-intensive industries and fossil fuels, with oil and gas alone accounting for <a href="https://www.bbc.com/future/article/20211115-climate-change-can-russia-leave-fossil-fuels-behind">35-40% of the federal budget revenue</a> in recent years. Hydrocarbons fuel Russia’s elite’s wealth and power but are also framed as a source of energy security and welfare for the country’s citizens.</p>
<h2>Russia’s decarbonisation at risk</h2>
<p>Until recently, Russia had long been seen as a <a href="https://www.opendemocracy.net/en/odr/what-can-we-expect-from-russia-at-cop26/">country with a lacklustre position in international climate negotiations</a>, at best a passive player and at worst an active saboteur of worldwide ambition. However, things have changed over the past years, most notably from November 2021 when its government adopted a <a href="http://static.government.ru/media/files/ADKkCzp3fWO32e2yA0BhtIpyzWfHaiUa.pdf">framework climate legislation</a> with a net-zero target by 2060. That year alone also saw it introduce a greenhouse gas emission reporting system for large emitters, adoption of its first national Climate Adaptation Plan and initiation of a carbon-trading experiment in its <a href="https://www.reuters.com/article/us-climate-change-russia-carbontrading-t-idUSKBN2AJ0NX">remote far Eastern region</a> aimed at reaching carbon neutrality by 2025.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/464520/original/file-20220520-12-hx9n1h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/464520/original/file-20220520-12-hx9n1h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/464520/original/file-20220520-12-hx9n1h.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/464520/original/file-20220520-12-hx9n1h.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/464520/original/file-20220520-12-hx9n1h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/464520/original/file-20220520-12-hx9n1h.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/464520/original/file-20220520-12-hx9n1h.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The government of the Russian island region of Sakhalin, in the Pacific Ocean north of Japan, has been experimenting with carbon trading and green technology in a bid to reach net-zero emissions by 2025.</span>
<span class="attribution"><span class="source">Angelina Davydova</span></span>
</figcaption>
</figure>
<p>Some will argue the impulse for these initiatives comes from outside the country. For example, as part of the European Union’s Green Deal package, the <a href="https://www.energymonitor.ai/policy/carbon-markets/eus-cbam-to-impact-russia-china">Carbon Border Adjustment Mechanism</a> (CBAM) is set to place a carbon price on imports entering the European single market from non-EU countries such as Russia from 2026. The border tariff, which would see imports covered by carbon pricing equivalent to Europe’s carbon market, the Emissions Trading System, has been credited with inspiring the Russian government and industry to finally take climate change seriously.</p>
<p>However, with every passing day of war these external incentives lose traction, making Russia’s domestic climate policy more uncertain than ever.</p>
<h2>Could Russia leave the Paris Agreement?</h2>
<p>On the one hand, it would be mistaken to claim all that is left of Russia’s climate policy is a tabula rasa. The truth is, today’s policy programmes and “green” business strategies do not fully hinge on foreign pressure. Although Russia’s parliament, the Duma, debated leaving the Paris Agreement <a href="https://iz.ru/1335953/valerii-voronov/eko-delo-v-gd-predlozhili-otkazatsia-ot-parizhskogo-soglasheniia">earlier this week</a>, there remains political will to uphold it. The chairman of the Duma’s Committee on Ecology, Natural Resources and Environmental Protection, Vyacheslav Fetisov, for example, has said:</p>
<blockquote>
<p>“Russia does not plan to withdraw from the Paris Climate Agreement [and] is not going to abandon the implementation of this most important environmental international legal instrument.”</p>
</blockquote>
<p>State agencies, companies, think tanks and other institutions that have developed “green” strategies over the past years, <a href="https://rawi.ru/2022/03/sohranit-li-biznes-v-rossii-kurs-na-dekarbonizaciyu/">insist on their enduring relevance</a> for the global fight against climate change, but also climate impacts on Russia and future trade prospects. The climate head of WWF Russia, Aleksey Kokorin, has even voiced optimism that gas surpluses resulting from sanctions could be used to substitute the country’s coal and prompt the country’s greenhouse gas emissions to drop.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/464521/original/file-20220520-13-on209d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/464521/original/file-20220520-13-on209d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/464521/original/file-20220520-13-on209d.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/464521/original/file-20220520-13-on209d.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/464521/original/file-20220520-13-on209d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/464521/original/file-20220520-13-on209d.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/464521/original/file-20220520-13-on209d.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The Russian state is strongly dependent on the exploitation of fossil fuels. Here, a photograph shows the Utrenneye field located on the Kara Sea shore line in the Arctic circle, some 2500 km from Moscow.</span>
<span class="attribution"><span class="source">Natalia Kolesnikova/AFP</span></span>
</figcaption>
</figure>
<p>And yet, it is undeniable that the <a href="https://theconversation.com/war-in-ukraine-russias-reputedly-sanction-proof-economy-shows-signs-of-stress-181109">economic crisis</a>, sanctions and strengthened anti-Western rhetoric brought on by the war have made it more difficult to pursue decarbonisation plans. Politicians and lobbyists who had already opposed decarbonisation efforts have seized the moment to <a href="https://spravedlivo.ru/12016310">demand a withdrawal from the Paris Agreement</a>.</p>
<p>Many businesses are taking advantage of the situation to pressure the government to roll back environmental regulation in a bid to help them cope with harsher economic circumstances, with <a href="https://greenpeace.ru/blogs/2022/04/22/v-rossii-oslabljajut-jekologicheskoe-zakonodatelstvo/">recent bills already pointing in this direction</a>. More specifically, there have been reports of <a href="https://iz.ru/1326653/valerii-voronov/terpiat-otlagatelstv-v-rossii-khotiat-otsrochit-sokrashchenie-parnikovykh-vybrosov">talks between the government and energy companies</a> over the possibility of relaxing greenhouse gas emission reporting and verification. For example, one of the country’s biggest oil suppliers, Lukoil, has pushed the government to scrap a legislation compelling large energy companies to verify their reporting on greenhouse gas emissions with an independent company starting from 1 January 2023.</p>
<p>Import restrictions on technology, the dwindling of foreign capital sources and the freezing of international programmes have further stalled plans to modernise the country’s old industries. Russia’s fledging renewables sector has also taken a hit, with some international investors (including Vestas, Fortum and ENEL) halting their plans in Russia or withdrawing from the country completely.</p>
<p>This has prompted politicians, businesspeople, and scientists to discuss alternatives to foreign technology and <a href="https://www.ng.ru/economics/2022-05-04/100_155304052022.html">domestic options to finance the energy transition</a>.</p>
<h2>Bleak future for Russia’s climate science</h2>
<p>Moreover, the sanctions have taken a serious toll on climate science in Russia, which matters to those who implement practical decarbonisation measures in Russia, but also to the global science community. It is particularly jarring in relation to other instances in Russian history when scientists succeeded in overcoming political tensions with the West. Despite the <a href="https://www.tandfonline.com/doi/full/10.1080/14682745.2021.1885377">Cold War</a>, climate scientists managed to advance global climate science within the 1972 US-USSR environmental agreement enabling the exchange of data, equipment and joint publications.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/464755/original/file-20220523-42302-8xjk15.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/464755/original/file-20220523-42302-8xjk15.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=388&fit=crop&dpr=1 600w, https://images.theconversation.com/files/464755/original/file-20220523-42302-8xjk15.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=388&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/464755/original/file-20220523-42302-8xjk15.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=388&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/464755/original/file-20220523-42302-8xjk15.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=488&fit=crop&dpr=1 754w, https://images.theconversation.com/files/464755/original/file-20220523-42302-8xjk15.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=488&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/464755/original/file-20220523-42302-8xjk15.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=488&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">US climatologist Alan D. Hecht (1944-2019) and the USSR’s Mikhail I. Budyko (1920-2001) discussing their joint publication on climate change in 1989.</span>
<span class="attribution"><span class="source">Alan D. Hecht</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>In contrast, governments and science bodies worldwide have now sanctioned Russian research institutions. Meanwhile, the EU has suspended Russia’s participation in its flagship research programme <a href="https://ec.europa.eu/commission/presscorner/detail/en/ip_22_1544">Horizon Europe</a> and national research councils of several European states paused collaborations with Russia.</p>
<p>Research areas that rely on foreign equipment are particularly affected. For instance, Germany’s Max Planck Institute (MPI) has received a <a href="https://www.zeit.de/2022/12/wissenschaft-ukraine-krieg-deutschland-russland-forschung">64-page list with electronic devices</a> that the EU forbids scientists to share with Russian colleagues on the grounds they could be used for military purposes. In early February, the Russian government announced <a href="https://www.themoscowtimes.com/2022/02/09/russia-aims-to-invest-79m-in-climate-research-by-2030-a76316">plans to invest 5.9 billion roubles</a> (at the time of writing, approximately $92 million) into climate and decarbonisation research, and create Russia’s own system to track carbon emissions.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/465007/original/file-20220524-24-qjue68.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/465007/original/file-20220524-24-qjue68.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/465007/original/file-20220524-24-qjue68.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/465007/original/file-20220524-24-qjue68.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/465007/original/file-20220524-24-qjue68.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/465007/original/file-20220524-24-qjue68.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/465007/original/file-20220524-24-qjue68.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A research station on the Island of Samoylov, northeastern Siberia.</span>
<span class="attribution"><span class="source">Anne Morgenstern/Alfred-Wegener Institute</span></span>
</figcaption>
</figure>
<p>However, Alexander Chernokulsky, a climatologist from the Institute of Atmospheric Physics at the Russian Academy of Sciences, told us the future of the project is unclear in the absence of foreign equipment. Similarly, for years Russian and German scientists have been measuring CO<sub>2</sub> concentration changes in the atmosphere from a tall tower observatory, <a href="https://www.zottoproject.org/">ZOTTO</a>, in the southwest Siberian region of Krasnoyarsk, considered a “hot spot” because of its potential for large carbon storage or leak. Here again, in an e-mail exchange with us, MPI scientist Sönke Zaehle has warned that the medium- and long-term future of the station are at risk from a lack of maintenance support from the German side.</p>
<p>Research in the Arctic is particularly crucial for our understanding of climate change. At least a dozen international collaborations with Russia have been stalled, here, too. The maintenance of long-term measuring systems crucial for climate modelling poses particular concerns. “There is this fear of a blind spot, no matter what research topic in the Arctic you approach,” Anne Morgenstern, a coordinator of the German Alfred Wegener Institute’s scientific cooperation with Russia, told us.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/464511/original/file-20220520-20-i7fpgo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/464511/original/file-20220520-20-i7fpgo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=374&fit=crop&dpr=1 600w, https://images.theconversation.com/files/464511/original/file-20220520-20-i7fpgo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=374&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/464511/original/file-20220520-20-i7fpgo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=374&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/464511/original/file-20220520-20-i7fpgo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=470&fit=crop&dpr=1 754w, https://images.theconversation.com/files/464511/original/file-20220520-20-i7fpgo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=470&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/464511/original/file-20220520-20-i7fpgo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=470&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A weather station in Russia’s northernmost region, Taymyr Peninsula in Siberia.</span>
<span class="attribution"><a class="source" href="http://www.grida.no/resources/2768">Peter Prokosch</a></span>
</figcaption>
</figure>
<p>Climate scientists in Russia have also lost access to the Climate Data Store, which provides a single point of access to a wide range of climate datasets for past, present and future climates, including satellite observations, in-situ measurements, climate model projections and seasonal forecasts. They can no longer either access supercomputers based in other countries, and the departure of technology companies such as <a href="https://www.intel.com/content/www/us/en/newsroom/news/russia-business-statement.html">Intel</a> will eventually lead to a deterioration of computing capacities in general, according to Evgeny Volodin, a climate modeller at the Institute of Computational Mathematics at the Russian Academy of Sciences.</p>
<p>Environmental concerns are at risk of being laid aside during wartime. However, as we stand at a point in earth history at which opportunities to mitigate climate catastrophe are fading, we believe subordinating climate issues to the dictates and temporalities of war is not an option. Attempts to stop the war have to stand alongside efforts to advance transnational climate cooperation and action, despite the damages and dilemmas caused by Russia’s war. Ambitious international climate agendas, including <a href="https://www.iisd.org/articles/analysis/phase-out-oil-gas-production">phasing out oil and gas production as quickly as possible</a>, are crucial to <a href="https://www.theguardian.com/environment/ng-interactive/2022/may/11/fossil-fuel-carbon-bombs-climate-breakdown-oil-gas">increase pressure on the fossil fuel industry</a> and the war machine, and to support those forces within Russia that are still holding on to decarbonisation.</p>
<hr>
<p><em>This article was co-written with Angelina Davydova, an environmental and climate journalist. She is currently a fellow of the Berlin-based <a href="https://mict-international.org/">Media in Cooperation and Transition (MICT) programme</a> and a coordinator with <a href="https://gijn.org/member/n-ost-germany/">N-ost</a>, a network for cross-border journalism.</em></p><img src="https://counter.theconversation.com/content/182995/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Alexander Vorbrugg a reçu des financements de Swiss National Science Foundation (SNSF). </span></em></p><p class="fine-print"><em><span>Katja Doose ne travaille pas, ne conseille pas, ne possède pas de parts, ne reçoit pas de fonds d'une organisation qui pourrait tirer profit de cet article, et n'a déclaré aucune autre affiliation que son organisme de recherche.</span></em></p>The war in Ukraine threatens to turn back the clock on Russia’s climate progress, with some calling on the country to leave the Paris Agreement and roll back environmental regulations.Katja Doose, Senior researcher, University of FribourgAlexander Vorbrugg, Geographer, University of BernLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1509342020-11-26T05:06:36Z2020-11-26T05:06:36ZAncient Earth had a thick, toxic atmosphere like Venus – until it cooled off and became liveable<figure><img src="https://images.theconversation.com/files/371399/original/file-20201125-29-1q9llhb.jpg?ixlib=rb-1.1.0&rect=0%2C68%2C1920%2C1112&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Tobias Stierli / NCCR PlanetS</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Earth is the only planet we know contains life. Is our planet special? Scientists over the years have mulled over what factors are essential for, or beneficial to, life. The answers will help us identify other potentially inhabited planets elsewhere in the galaxy.</p>
<p>To understand what conditions were like in Earth’s early years, our research tried to recreate the chemical balance of the boiling magma ocean that covered the planet billions of years ago, and conducted experiments to see what kind of atmosphere it would have produced. Working with colleagues in France and the United States, we <a href="https://advances.sciencemag.org/content/6/48/eabd1387">found</a> Earth’s first atmosphere was likely a thick, inhospitable soup of carbon dioxide and nitrogen, much like what we see on Venus today.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/if-there-is-life-on-venus-how-could-it-have-got-there-origin-of-life-experts-explain-146407">If there is life on Venus, how could it have got there? Origin of life experts explain</a>
</strong>
</em>
</p>
<hr>
<h2>How Earth got its first atmosphere</h2>
<p>A rocky planet like Earth is born through a process called “accretion”, in which initially small particles clump together under the pull of gravity to form larger and larger bodies. The smaller bodies, called “planetesimals”, look like asteroids, and the next size up are “planetary embryos”. There may have been many planetary embryos in the early Solar System, but the only one that still survives is Mars, which is not a fully fledged planet like Earth or Venus.</p>
<p>The late stages of accretion involve giant impacts that release enormous amounts of energy. We think the last impact in Earth’s accretion involved a Mars-sized embryo hitting the growing Earth, spinning off our Moon, and melting most or all of what was left. </p>
<p>The impact would have left Earth covered in a global sea of molten rock called a “magma ocean”. The magma ocean would have leaked hydrogen, carbon, oxygen and nitrogen gases, to form Earth’s first atmosphere. </p>
<h2>What the first atmosphere was like</h2>
<p>We wanted to know exactly what kind of atmosphere this would have been, and how it would have changed as it, and the magma ocean beneath, cooled down. The crucial thing to understand is what was happening with the element oxygen, because it controls how the other elements combine. </p>
<p>If there was little oxygen around, the atmosphere would have been rich in hydrogen (H₂), ammonia (NH₃) and carbon monoxide (CO) gases. With abundant oxygen, it would have been made of a much friendlier mix of gases: carbon dioxide (CO₂), water vapour (H₂O) and molecular nitrogen (N₂).</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-rise-and-fall-of-oxygen-18954">The rise and fall of oxygen</a>
</strong>
</em>
</p>
<hr>
<p>So we needed to work out the chemistry of oxygen in the magma ocean. The key was to determine how much oxygen was chemically bonded to the element iron. If there’s a lot of oxygen, it bonds to iron in a 3:2 ratio, but if there is less oxygen we see a 1:1 ratio. The actual ratio may vary between these extremes. </p>
<p>When the magma ocean eventually cooled down, it became Earth’s mantle (the layer of rock beneath the planet’s crust). So we made the assumption that the oxygen-iron bonding ratios in the magma ocean would have been the same as they are in the mantle today. </p>
<p>We have plenty of samples of the mantle, some brought to the surface by volcanic eruptions and others by tectonic processes. From these, we could work out how to put together a matching mix of chemicals in the laboratory.</p>
<h2>In the lab</h2>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/371409/original/file-20201126-25-17e307k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/371409/original/file-20201126-25-17e307k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/371409/original/file-20201126-25-17e307k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=844&fit=crop&dpr=1 600w, https://images.theconversation.com/files/371409/original/file-20201126-25-17e307k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=844&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/371409/original/file-20201126-25-17e307k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=844&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/371409/original/file-20201126-25-17e307k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1061&fit=crop&dpr=1 754w, https://images.theconversation.com/files/371409/original/file-20201126-25-17e307k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1061&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/371409/original/file-20201126-25-17e307k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1061&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">In the experiments we levitated a miniature magma ocean on a stream of gases, kept molten by the heat of a powerful laser. This allowed us to calibrate the chemical reaction between iron and oxygen in the magma and relate this to the composition of the atmosphere.</span>
<span class="attribution"><span class="source">IPGP</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>We determined this atmosphere was composed of CO₂ and H₂O. Nitrogen would have been in its elemental form (N₂) rather than the toxic gas ammonia (NH₃). </p>
<p>But what would have happened when the magma ocean cooled down? It seems the early Earth cooled enough for the water vapour to condense out of the atmosphere, forming oceans of liquid water like we see today. This would have left an atmosphere with 97% CO₂ and 3% N₂, at a total pressure roughly 70 times today’s atmospheric pressure. Talk about a greenhouse effect! But the Sun was <a href="https://en.wikipedia.org/wiki/Faint_young_Sun_paradox#Carbon_dioxide_as_a_greenhouse_gas">less than three-quarters</a> as bright then as it is now. </p>
<h2>How Earth avoided the fate of Venus</h2>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/371429/original/file-20201126-17-8z655k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/371429/original/file-20201126-17-8z655k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/371429/original/file-20201126-17-8z655k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=616&fit=crop&dpr=1 600w, https://images.theconversation.com/files/371429/original/file-20201126-17-8z655k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=616&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/371429/original/file-20201126-17-8z655k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=616&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/371429/original/file-20201126-17-8z655k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=774&fit=crop&dpr=1 754w, https://images.theconversation.com/files/371429/original/file-20201126-17-8z655k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=774&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/371429/original/file-20201126-17-8z655k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=774&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 ultraviolet view shows bands of clouds in the atmosphere of Venus.</span>
<span class="attribution"><a class="source" href="http://www.darts.isas.jaxa.jp/pub/doi/VCO-00003.html">ISAS / JAXA</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>This ratio of CO₂ to N₂ is strikingly like the present atmosphere on Venus. So why did Venus, but not Earth, retain the hellishly hot and toxic environment we observe today? </p>
<p>The answer is that Venus was too close to the Sun. It simply never cooled down enough to form water oceans. Instead, the H₂O in the atmosphere stayed as water vapour and was slowly but inexorably lost to space. </p>
<p>On the early Earth, the water oceans instead slowly but steadily drew down CO₂ from the atmosphere by reaction with rock – a reaction known to science for the past 70 years as the “<a href="https://pubs.geoscienceworld.org/msa/ammin/article/104/10/1365/573790/Carbonation-and-the-Urey-reaction">Urey reaction</a>”, after the Nobel prizewinner who discovered it – and reducing atmospheric pressure to what we observe today. </p>
<p>So, although both planets started out almost identically, it is their different distances from the Sun that put them on divergent paths. Earth became more conducive to life while Venus became increasingly inhospitable.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/ancient-minerals-on-earth-can-help-explain-the-early-solar-system-46991">Ancient minerals on Earth can help explain the early solar system</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/150934/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Antony Burnham receives funding from the Australian Synchrotron. This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under contract no. DE-AC02-06CH11357.</span></em></p><p class="fine-print"><em><span>Hugh O'Neill received funding from the Australian Research Council (grant FL130100066)</span></em></p>Unlike our hellish neighbour Venus, Earth was far enough from the Sun for liquid water to form and create a more hospitable environment for life.Antony Burnham, Research Fellow, Research School of Earth Sciences, Australian National UniversityHugh O'Neill, Professor, Research School of Earth Sciences, Australian National UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1434992020-07-31T10:38:48Z2020-07-31T10:38:48ZJohn Tyndall: the forgotten co-founder of climate science<figure><img src="https://images.theconversation.com/files/350588/original/file-20200731-15-l6e2e1.jpg?ixlib=rb-1.1.0&rect=0%2C265%2C2363%2C2773&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">John Tyndall.</span> <span class="attribution"><span class="source">wellcome/wikipedia</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>It is surprising that the Irish scientist John Tyndall, born 200 years ago on August 2 1820, is not better known. This is despite the existence of the <a href="https://www.tyndall.ac.uk/">Tyndall Centre for Climate Change Research</a>, <a href="https://www.tyndall.ie/about-us">the Tyndall National Institute</a> and <a href="https://www.summitpost.org/pic-tyndall-south-ridge-deffeyes-carrel-route/795303">the Pic Tyndall</a> summit on the Matterhorn in the Alps. There are even several <a href="https://www.mountain-forecast.com/peaks/Mount-Tyndall">Mount Tyndalls</a>, Tyndall glaciers and <a href="http://redplanet.asu.edu/?p=16068">Tyndall craters</a> on the Moon and Mars. </p>
<p>From that, you could surmise that he was both a significant scientist and a notable mountaineer. Yet, due to unfortunate circumstances, he is no household name. </p>
<p>In 1859, Tyndall showed that gases including carbon dioxide and water vapour <a href="https://earthobservatory.nasa.gov/features/Tyndall">can absorb heat</a>. His heat source was not the Sun, but radiation from a copper cube containing boiling water. In modern terms, this was <a href="https://searchnetworking.techtarget.com/definition/infrared-radiation#:%7E:text=Infrared%20radiation%20(IR)%2C%20sometimes,than%20those%20of%20radio%20waves.">infrared radiation</a> – just like that emanating from the Earth’s surface. </p>
<p>Previous work had shown that the Earth’s temperature was higher than expected, which was put down to the atmosphere acting as an insulator. But no-one knew the explanation for what we now call <a href="https://climatekids.nasa.gov/greenhouse-effect/">the greenhouse effect</a> – gases in the atmosphere trapping heat.</p>
<p>What Tyndall did was to discover and explain this mechanism. He <a href="https://www.climate-lab-book.ac.uk/2018/john-tyndall-founder-of-climate-science/#:%7E:text=But%20he%20concluded%3A%20'Thus%20the,now%20call%20the%20greenhouse%20effect.">wrote</a>: “Thus the atmosphere admits of the entrance of the solar heat; but checks its exit, and the result is a tendency to accumulate heat at the surface of the planet.”</p>
<p>He realised that any change in the amount of water vapour or carbon dioxide in the atmosphere could change the climate. His work therefore set a foundation for our understanding of climate change and meteorology.</p>
<p>Tyndall was not, however, the first to make the climate link. That prize goes to the American <a href="https://royalsocietypublishing.org/doi/10.1098/rsnr.2018.0066">Eunice Foote</a>, who showed in 1856 using sunlight that carbon dioxide could absorb heat. She suggested that an increase in carbon dioxide would result in a warmer planet. </p>
<p>Research suggests Tyndall <a href="https://royalsocietypublishing.org/doi/10.1098/rsnr.2018.0066">was unaware of her work</a>. He would no doubt have been surprised to find that an amateur woman had beaten him to a general demonstration of the absorption of heat by carbon dioxide. To his discredit, he did not believe that women possessed the same creative abilities in science as men. </p>
<figure class="align-center ">
<img alt="Sun shining on the Earth with description of greenhouse effect." src="https://images.theconversation.com/files/350593/original/file-20200731-14-1sxsuqx.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/350593/original/file-20200731-14-1sxsuqx.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=428&fit=crop&dpr=1 600w, https://images.theconversation.com/files/350593/original/file-20200731-14-1sxsuqx.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=428&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/350593/original/file-20200731-14-1sxsuqx.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=428&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/350593/original/file-20200731-14-1sxsuqx.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=538&fit=crop&dpr=1 754w, https://images.theconversation.com/files/350593/original/file-20200731-14-1sxsuqx.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=538&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/350593/original/file-20200731-14-1sxsuqx.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=538&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 greenhouse effect.</span>
<span class="attribution"><span class="source">US EPA</span></span>
</figcaption>
</figure>
<p>Tyndall made many other discoveries in disparate fields of physics and biology. He made his initial reputation in the obscure topic of diamagnetism, the weak repulsion of substances by a magnet. That brought him to the notice of influential people such as physicist <a href="http://www.bbc.co.uk/history/historic_figures/faraday_michael.shtml">Michael Faraday</a>. </p>
<p>Within a few years he was a fellow the <a href="https://royalsociety.org/">Royal Society</a>, Britain’s most prestigious scientific body, and professor of natural philosophy at the <a href="https://www.rigb.org/">Royal Institution</a>, where he remained for the rest of his scientific career.</p>
<p>Soon he was at work on understanding glacier structure and motion. After that came the work on the absorption of heat by gases, and then the action of light in causing chemical changes. In the process Tyndall explained why the sky is blue – blue light is <a href="https://www.britannica.com/science/Tyndall-effect">scattered more by gases</a> in the sky than other colours because of its short wavelength. </p>
<p>He also discovered “Tyndallisation” – a bacteriological technique of sterilisation – when undertaking experiments alongside French biologist <a href="https://www.livescience.com/43007-louis-pasteur.html">Louis Pasteur</a> to support the theory that germs can cause disease. That line of research led to the invention of a respirator for firefighters, though Tyndall never took out a patent. He committed himself to fundamental research, confident that others would generate useful applications.</p>
<h2>Science versus religion</h2>
<p>As a public intellectual, Tyndall’s was one of the loudest voices advocating a scientific explanation for the natural world and for life itself, a <a href="https://plato.stanford.edu/entries/naturalism/">scientific naturalism</a>. In this, religion and theology had no place. He gave the starkest statement of this position in his famous, indeed notorious, <a href="https://www.cambridge.org/core/books/science-and-religion-in-the-19th-century/john-tyndall-the-belfast-address-nature-20-august-1874/300BD8E07285BE541B752953F2118E35">Belfast Address</a>, in 1874.</p>
<p>In the Ulster Hall, he thundered: </p>
<blockquote>
<p>We claim, and we shall wrest from theology, the entire domain of cosmological theory. All schemes and systems which thus infringe upon the domain of science must, insofar as they do this, submit to its control, and relinquish all thought of controlling it.</p>
</blockquote>
<p>But he was never one to belittle the role of religion. Science, for him, provided reliable knowledge of the world. Religion met people’s emotional needs, a role he thought might eventually to be replaced by poetry.</p>
<h2>Representing the past</h2>
<p>Tyndall didn’t marry until he was in his 50s, but his beloved Louisa killed him by accident in 1893 – giving him an overdose of the wrong medicine in the dark. She then gathered huge amounts of material to write his biography, but died 47 years later with it uncompleted. </p>
<p>Her drafts, as well as Tydnall’s diaries, laboratory notebooks and thousands of letters, are held at the <a href="https://www.rigb.org/">Royal Institution</a> in London. All his correspondence is currently being published by the <a href="https://tyndallproject.com/">Tyndall Correspondence Project</a>. I was able to use the material when writing my biography <a href="https://global.oup.com/academic/product/the-ascent-of-john-tyndall-9780198788942"><em>The Ascent of John Tyndall</em></a>, just released in paperback for his birthday.</p>
<figure class="align-center ">
<img alt="Painting of the neoclassical Royal Institution building in London." src="https://images.theconversation.com/files/350594/original/file-20200731-15-1gmqhnj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/350594/original/file-20200731-15-1gmqhnj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=398&fit=crop&dpr=1 600w, https://images.theconversation.com/files/350594/original/file-20200731-15-1gmqhnj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=398&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/350594/original/file-20200731-15-1gmqhnj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=398&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/350594/original/file-20200731-15-1gmqhnj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=500&fit=crop&dpr=1 754w, https://images.theconversation.com/files/350594/original/file-20200731-15-1gmqhnj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=500&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/350594/original/file-20200731-15-1gmqhnj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=500&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The Royal Institution of Great Britain from about 1838.</span>
</figcaption>
</figure>
<p>Louisa’s failure to write a biography is part of the reason he is not better known, but he also had the misfortune to die on the cusp of revolutionary discoveries in physics such as quantum theory and relativity. In a sense, he represented the past.</p>
<p>But today, climate research is more important and pressing than ever – and scientists are making huge strides. I am sure Tyndall would be gratified to find that his foundational work had proved so important. </p>
<p>In his time, however, few people made the connection between the burning of fossil fuels and possible global warming. Tyndall was more worried that Britain would run out of coal and be unable to compete economically with America, given its vaster supplies. One imagines though that, as a scientist, he would be convinced by the current evidence.</p>
<p>Climate science is now the future rather than the past, and it is therefore time to recognise and reinstate Tyndall as a major Irish scientist, mountaineer and public intellectual.</p><img src="https://counter.theconversation.com/content/143499/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Roland Jackson does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>The man who explained the greenhouse effect was accidentally killed by his wife.Roland Jackson, Research Associate in the History of Science and Visiting Fellow at the Royal Institution, UCLLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1411942020-06-23T20:16:44Z2020-06-23T20:16:44ZClimate Explained: what Earth would be like if we hadn’t pumped greenhouse gases into the atmosphere<figure><img src="https://images.theconversation.com/files/343101/original/file-20200622-75483-xbfslh.jpg?ixlib=rb-1.1.0&rect=765%2C100%2C5954%2C2458&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">OSORIOartist/Shutterstock</span></span></figcaption></figure><figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/287622/original/file-20190811-144878-bvgm9l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/287622/original/file-20190811-144878-bvgm9l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/287622/original/file-20190811-144878-bvgm9l.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/287622/original/file-20190811-144878-bvgm9l.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/287622/original/file-20190811-144878-bvgm9l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/287622/original/file-20190811-144878-bvgm9l.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/287622/original/file-20190811-144878-bvgm9l.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="attribution"><a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
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<p><em><strong><a href="https://theconversation.com/nz/topics/climate-explained-74664">Climate Explained</a></strong> is a collaboration between The Conversation, Stuff and the New Zealand Science Media Centre to answer your questions about climate change.</em> </p>
<p><em>If you have a question you’d like an expert to answer, please send it to climate.change@stuff.co.nz</em></p>
<p><em><strong>This week, Climate Explained answers two similar questions.</strong></em></p>
<blockquote>
<p><strong>If humans had not contributed to greenhouses gases in any way at all, what would the global temperature be today, compared to the 1800s before industrialisation?</strong></p>
</blockquote>
<p>and</p>
<blockquote>
<p><strong>My question is what happens when all the greenhouse gases are eliminated? What keeps the planet from cooling past a point that is good?</strong></p>
</blockquote>
<p>Earth’s atmosphere is a remarkably thin layer of gases that sustain life. </p>
<p>The diameter of Earth is 12,742km and the atmosphere is about 100km thick. If you took a model globe and wrapped it up, a single sheet of tissue paper would represent the thickness of the atmosphere.</p>
<p>The gases that make up Earth’s atmosphere are mostly nitrogen and oxygen, and small quantities of trace gases such as argon, neon, helium, the <a href="https://ozonewatch.gsfc.nasa.gov/facts/SH.html">protective ozone layer</a> and various greenhouse gases – so named because they trap heat emitted by Earth. </p>
<p>The most abundant greenhouse gas in Earth’s atmosphere is water vapour - and it is this gas that provides the natural greenhouse effect. Without this and the naturally occurring quantities of other greenhouse gases, Earth would be <a href="https://niwa.co.nz/our-science/climate/information-and-resources/clivar/greenhouse">about 33°C colder</a> and uninhabitable to life as we know it.</p>
<h2>Changing Earth’s atmosphere</h2>
<p>Since pre-industrial times, human activities have led to the accumulation of greenhouse gases such as carbon dioxide, methane and nitrous oxide in the atmosphere. The concentration of <a href="https://scrippsco2.ucsd.edu/">atmospheric carbon dioxide has risen</a> from about 280 parts per million (ppm) before the <a href="https://en.wikipedia.org/wiki/Industrial_Revolution">first industrial revolution</a> some 250 years ago, to a <a href="https://www.washingtonpost.com/weather/2020/06/04/carbon-dioxide-record-2020/">new high since records began</a> of just over 417ppm. As a result of continued increases, the global average temperature has climbed by just over <a href="https://earthobservatory.nasa.gov/world-of-change/global-temperatures">1°C since pre-industrial times</a>.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/climate-explained-why-carbon-dioxide-has-such-outsized-influence-on-earths-climate-123064">Climate explained: why carbon dioxide has such outsized influence on Earth's climate</a>
</strong>
</em>
</p>
<hr>
<p>While these long-lived greenhouse gases have raised Earth’s average surface temperature, human activities have altered atmospheric composition in other ways as well. Particulate matter in the atmosphere, such as soot and dust, can cause <a href="https://www.who.int/gho/phe/outdoor_air_pollution/burden_text/en/">health problems</a> and degrades air quality in many industrialised and urban regions. </p>
<p>Particulate matter can <a href="https://www.ipcc.ch/site/assets/uploads/2018/02/WG1AR5_Chapter08_FINAL.pdf">partially offset greenhouse gas warming</a>, but its climate effects depend on its composition and <a href="https://www.nature.com/articles/s41467-018-05838-6">geographical distribution</a>. Climate in the southern hemisphere has also been affected by chlorofluorocarbons (CFCs), which led to the development of the <a href="https://www.scientificamerican.com/article/shrinking-ozone-hole-climate-change-are-causing-atmospheric-tug-of-war/">Antarctic ozone hole</a>. </p>
<p>If people had not altered the composition of the atmosphere at all through emitting greenhouse gases, particulate matter and ozone-destroying CFCs, we would expect the global average temperature today to be similar to the pre-industrial period – although some short-term variation associated with the Sun, <a href="https://earthdata.nasa.gov/learn/sensing-our-planet/volcanoes-and-climate-change">volcanic eruptions</a> and internal variability would still have occurred. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/what-is-a-pre-industrial-climate-and-why-does-it-matter-78601">What is a pre-industrial climate and why does it matter?</a>
</strong>
</em>
</p>
<hr>
<p>In a world that is about 1°C warmer than during pre-industrial times, New Zealand is already facing the environmental and <a href="https://www.newsroom.co.nz/2020/06/17/1233114/nzs-climate-change-toll-tops-800m-from-just-two-droughts">economic costs</a> associated with climate change. The former head of the UN Framework Convention on Climate Change (<a href="https://unfccc.int/process-and-meetings/the-convention/what-is-the-united-nations-framework-convention-on-climate-change">UNFCCC</a>), Christiana Figueres, <a href="https://www.rnz.co.nz/programmes/post-covid-podcast/story/2018748032/after-the-virus-the-environment">argues</a> that with trillions of dollars being spent around the world in economic stimulus packages following the COVID-19 pandemic, we need strong commitments to a low-carbon future if the world is to limit warming to 1.5°C above pre-industrial levels. </p>
<h2>What needs to happen</h2>
<p>Greenhouse gases have long lifetimes – about a decade for methane and hundreds to thousands of years for carbon dioxide. We will need to reduce emissions aggressively over a sustained period, until their abundance in the atmosphere starts to decline. </p>
<p>When New Zealand entered the Level 4 coronavirus lockdown in March 2020, almost two weeks passed (the incubation period of the virus) before the number of new cases started to decline. Waiting for atmospheric carbon dioxide concentrations to decrease, even while we reduce emissions, will be similar, except we’ll be <a href="https://scripps.ucsd.edu/programs/keelingcurve/2020/03/11/what-does-it-take-for-the-coronavirus-or-other-major-economic-events-to-affect-global-carbon-dioxide-readings/">waiting for decades</a>. </p>
<p>It is very unlikely that we could ever reduce greenhouse gas concentrations to the point that it becomes dangerous for life as we know it. Doing so would involve overcoming the natural greenhouse effect.</p>
<p>Recent <a href="https://www.nature.com/articles/s41558-018-0091-3?proof=trueIn">research</a> into greenhouse gas emission scenarios provides guidance on what will need to happen to stabilise Earth’s temperature at 1.5°C above pre-industrial levels. A rapid transition away from fossil fuels toward low-carbon energy is imperative; some form of carbon dioxide capture to remove it from the atmosphere may also be necessary. </p>
<p>Short-term and scattered climate policy will not be sufficient to support the transitions we need, and achieving 1.5°C will not be possible as long as global inequalities remain high.</p><img src="https://counter.theconversation.com/content/141194/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Laura Revell receives funding from the Ministry of Business, Innovation and Employment, the Deep South National Science Challenge and the Royal Society of New Zealand Marsden fund.</span></em></p>If we had not altered the composition of the atmosphere at all through emitting greenhouse gases, particulate matter and ozone-destroying chemicals, the average temperature would have remained stable.Laura Revell, Senior Lecturer in Environmental Physics, University of CanterburyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1230642019-09-13T11:37:22Z2019-09-13T11:37:22ZClimate explained: why carbon dioxide has such outsized influence on Earth’s climate<figure><img src="https://images.theconversation.com/files/292045/original/file-20190911-190061-6k37df.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The Orbiting Carbon Observatory satellite makes precise measurements of Earth's carbon dioxide levels from space.</span> <span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Orbiting_Carbon_Observatory_2#/media/File:Orbiting_Carbon_Observatory-2_artist_rendering_(PIA18374).jpg">NASA/JPL</a></span></figcaption></figure><figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/287622/original/file-20190811-144878-bvgm9l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/287622/original/file-20190811-144878-bvgm9l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/287622/original/file-20190811-144878-bvgm9l.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/287622/original/file-20190811-144878-bvgm9l.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/287622/original/file-20190811-144878-bvgm9l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/287622/original/file-20190811-144878-bvgm9l.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/287622/original/file-20190811-144878-bvgm9l.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="attribution"><a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
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<p><em><strong><a href="https://theconversation.com/au/topics/climate-explained-74664">Climate Explained</a></strong> is a collaboration between The Conversation, Stuff and the New Zealand Science Media Centre to answer your questions about climate change.</em> </p>
<p><em>If you have a question you’d like an expert to answer, please send it to <a href="mailto:climate.change@stuff.co.nz">climate.change@stuff.co.nz</a></em></p>
<blockquote>
<p><strong>I heard that carbon dioxide makes up 0.04% of the world’s atmosphere. Not 0.4% or 4%, but 0.04%! How can it be so important in global warming if it’s such a small percentage?</strong></p>
</blockquote>
<p>I am often asked how carbon dioxide can have an important effect on global climate when its concentration is so small – just <a href="https://www.britannica.com/science/atmosphere">0.041% of Earth’s atmosphere</a>. And human activities are responsible for <a href="https://e360.yale.edu/features/how-the-world-passed-a-carbon-threshold-400ppm-and-why-it-matters">just 32% of that amount</a>. </p>
<p>I study the importance of atmospheric gases for <a href="https://haqast.org/staff/west-jason/">air pollution and climate change</a>. The key to carbon dioxide’s strong influence on climate is its ability to absorb heat emitted from our planet’s surface, keeping it from escaping out to space.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/292035/original/file-20190911-190031-4lt7v0.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/292035/original/file-20190911-190031-4lt7v0.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/292035/original/file-20190911-190031-4lt7v0.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=360&fit=crop&dpr=1 600w, https://images.theconversation.com/files/292035/original/file-20190911-190031-4lt7v0.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=360&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/292035/original/file-20190911-190031-4lt7v0.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=360&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/292035/original/file-20190911-190031-4lt7v0.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=452&fit=crop&dpr=1 754w, https://images.theconversation.com/files/292035/original/file-20190911-190031-4lt7v0.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=452&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/292035/original/file-20190911-190031-4lt7v0.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=452&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 ‘Keeling Curve,’ named for scientist Charles David Keeling, tracks the accumulation of carbon dioxide in Earth’s atmosphere, measured in parts per million.</span>
<span class="attribution"><a class="source" href="https://scripps.ucsd.edu/programs/keelingcurve/wp-content/plugins/sio-bluemoon/graphs/mlo_full_record.png">Scripps Institution of Oceanography</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Early greenhouse science</h2>
<p>The scientists who first identified carbon dioxide’s importance for climate in the 1850s were also surprised by its influence. Working separately, <a href="https://earthobservatory.nasa.gov/features/Tyndall">John Tyndall</a> in England and <a href="https://www.climate.gov/news-features/features/happy-200th-birthday-eunice-foote-hidden-climate-science-pioneer">Eunice Foote</a> in the United States found that carbon dioxide, water vapor and methane all absorbed heat, while more abundant gases did not.</p>
<p>Scientists had already calculated that the Earth was about 59 degrees Fahrenheit (33 degrees Celsius) <a href="https://www.giss.nasa.gov/research/briefs/ma_01/">warmer than it should be</a>, given the amount of sunlight reaching its surface. The best explanation for that discrepancy was that the atmosphere retained heat to warm the planet.</p>
<p>Tyndall and Foote showed that nitrogen and oxygen, which together account for 99% of the atmosphere, had essentially no influence on Earth’s temperature because they did not absorb heat. Rather, they found that gases present in much smaller concentrations were entirely responsible for maintaining temperatures that made the Earth habitable, by trapping heat to create <a href="https://history.aip.org/climate/co2.htm">a natural greenhouse effect</a>.</p>
<h2>A blanket in the atmosphere</h2>
<p>Earth constantly receives energy from the sun and radiates it back into space. For the planet’s temperature to remain constant, the net heat it receives from the sun must be balanced by outgoing heat that it gives off. </p>
<p>Since the sun is hot, it gives off energy in the form of shortwave radiation at mainly ultraviolet and visible wavelengths. Earth is much cooler, so it emits heat as infrared radiation, which has longer wavelengths. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/291990/original/file-20190911-190044-10ngpxj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/291990/original/file-20190911-190044-10ngpxj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/291990/original/file-20190911-190044-10ngpxj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=225&fit=crop&dpr=1 600w, https://images.theconversation.com/files/291990/original/file-20190911-190044-10ngpxj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=225&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/291990/original/file-20190911-190044-10ngpxj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=225&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/291990/original/file-20190911-190044-10ngpxj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=282&fit=crop&dpr=1 754w, https://images.theconversation.com/files/291990/original/file-20190911-190044-10ngpxj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=282&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/291990/original/file-20190911-190044-10ngpxj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=282&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 electromagnetic spectrum is the range of all types of EM radiation – energy that travels and spreads out as it goes. The sun is much hotter than the Earth, so it emits radiation at a higher energy level, which has a shorter wavelength.</span>
<span class="attribution"><a class="source" href="https://imagine.gsfc.nasa.gov/Images/science/EM_spectrum_compare_level1_lg.jpg">NASA</a></span>
</figcaption>
</figure>
<p>Carbon dioxide and other heat-trapping gases have molecular structures that enable them to absorb infrared radiation. The bonds between atoms in a molecule can vibrate in particular ways, like the pitch of a piano string. When the energy of a photon corresponds to the frequency of the molecule, it is absorbed and its energy transfers to the molecule. </p>
<p>Carbon dioxide and other heat-trapping gases have three or more atoms and frequencies that <a href="http://forecast.uchicago.edu/archer.ch4.greenhouse_gases.pdf">correspond to infrared radiation emitted by Earth</a>. Oxygen and nitrogen, with just two atoms in their molecules, do not absorb infrared radiation. </p>
<p>Most incoming shortwave radiation from the sun passes through the atmosphere without being absorbed. But most outgoing infrared radiation is absorbed by heat-trapping gases in the atmosphere. Then they can release, or re-radiate, that heat. Some returns to Earth’s surface, keeping it warmer than it would be otherwise.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/292029/original/file-20190911-190021-nzy6or.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/292029/original/file-20190911-190021-nzy6or.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/292029/original/file-20190911-190021-nzy6or.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/292029/original/file-20190911-190021-nzy6or.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/292029/original/file-20190911-190021-nzy6or.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/292029/original/file-20190911-190021-nzy6or.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/292029/original/file-20190911-190021-nzy6or.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/292029/original/file-20190911-190021-nzy6or.png?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">Earth receives solar energy from the sun (yellow), and returns energy back to space by reflecting some incoming light and radiating heat (red). Greenhouse gases trap some of that heat and return it to the planet’s surface.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Earth%27s_energy_budget#/media/File:Diagram_showing_the_Earth's_energy_budget,_which_includes_the_greenhouse_effect_(NASA).png">NASA via Wikimedia</a></span>
</figcaption>
</figure>
<h2>Research on heat transmission</h2>
<p>During the Cold War, the absorption of infrared radiation by many different gases was studied extensively. The work was led by the U.S. Air Force, which was developing heat-seeking missiles and needed to understand how to detect heat passing through air. </p>
<p>This research enabled scientists to understand the climate and atmospheric composition of all planets in the solar system by observing their infrared signatures. For example, Venus is about 870 F (470 C) because its thick atmosphere is <a href="https://en.wikipedia.org/wiki/Atmosphere_of_Venus">96.5% carbon dioxide</a>.</p>
<p>It also informed weather forecast and climate models, allowing them to quantify how much infrared radiation is retained in the atmosphere and returned to Earth’s surface. </p>
<p>People sometimes ask me why carbon dioxide is important for climate, given that water vapor absorbs more infrared radiation and the two gases absorb at several of the same wavelengths. The reason is that Earth’s upper atmosphere controls the radiation that escapes to space. The upper atmosphere is much less dense and contains much less water vapor than near the ground, which means that <a href="http://www.realclimate.org/index.php/archives/2007/06/a-saturated-gassy-argument/">adding more carbon dioxide significantly influences</a> how much infrared radiation escapes to space.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/X2TOrKdJsqs?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Carbon dioxide levels rise and fall around the world, changing seasonally with plant growth and decay.</span></figcaption>
</figure>
<h2>Observing the greenhouse effect</h2>
<p>Have you ever noticed that deserts are often colder at night than forests, even if their average temperatures are the same? Without much water vapor in the atmosphere over deserts, the radiation they give off escapes readily to space. In more humid regions radiation from the surface is trapped by water vapor in the air. Similarly, cloudy nights tend to be warmer than clear nights because more water vapor is present.</p>
<p>The influence of carbon dioxide can be seen in past changes in climate. Ice cores from over the past million years have shown that carbon dioxide concentrations were high during warm periods – about 0.028%. During ice ages, when <a href="https://earthobservatory.nasa.gov/features/GlobalWarming/page3.php">the Earth was roughly 7 to 13 F</a> (4-7 C) cooler than in the 20th century, carbon dioxide made up <a href="https://earthobservatory.nasa.gov/features/CarbonCycle/page4.php">only about 0.018%</a> of the atmosphere. </p>
<p>Even though water vapor is more important for the natural greenhouse effect, changes in carbon dioxide have driven past temperature changes. In contrast, water vapor levels in the atmosphere respond to temperature. As Earth becomes warmer, its <a href="https://www.newscientist.com/article/dn11652-climate-myths-carbon-dioxide-isnt-the-most-important-greenhouse-gas/">atmosphere can hold more water vapor</a>, which <a href="https://www.nasa.gov/topics/earth/features/vapor_warming.html">amplifies the initial warming</a> in a process called the “water vapor feedback.” <a href="https://www.acs.org/content/acs/en/climatescience/climatesciencenarratives/its-water-vapor-not-the-co2.html">Variations in carbon dioxide</a> have therefore been the <a href="https://science.sciencemag.org/content/330/6002/356?maxtoshow=&hits=10&RESULTFORMAT=&fulltext=gavin+schmidt&searchid=1&FIRSTINDEX=0&resourcetype=HWCIT">controlling influence</a> on past climate changes. </p>
<h2>Small change, big effects</h2>
<p>It shouldn’t be surprising that a small amount of carbon dioxide in the atmosphere can have a big effect. We take pills that are a tiny fraction of our body mass and expect them to affect us. </p>
<p>Today the level of carbon dioxide is higher than at any time in human history. Scientists widely agree that Earth’s average surface temperature <a href="https://climate.nasa.gov/news/2841/2018-fourth-warmest-year-in-continued-warming-trend-according-to-nasa-noaa/">has already increased by about 2 F</a> (1 C) since the 1880s, and that human-caused increases in carbon dioxide and other heat-trapping gases are <a href="https://www.ipcc.ch/site/assets/uploads/2018/02/WG1AR5_SPM_FINAL.pdf">extremely likely to be responsible</a>. </p>
<p>Without action to control emissions, <a href="https://skepticalscience.com/rcp.php?t=3">carbon dioxide might reach 0.1% of the atmosphere by 2100</a>, more than triple the level before the Industrial Revolution. This would be a <a href="https://www.scientificamerican.com/article/the-last-great-global-warming/">faster change than transitions in Earth’s past</a> that had huge consequences. Without action, this little sliver of the atmosphere will cause big problems.</p>
<p>[ <em>Deep knowledge, daily.</em> <a href="https://theconversation.com/us/newsletters?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=deepknowledge">Sign up for The Conversation’s newsletter</a>. ]</p><img src="https://counter.theconversation.com/content/123064/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jason West receives funding tfrom the EPA, NASA, NSF, the Donald and Jennifer Holzworth Faculty Acceleration Fund in Climate Change, and the State of North Carolina.</span></em></p>Carbon dioxide makes up less than one-twentieth of 1% of Earth’s atmosphere. How does this relatively scarce gas control Earth’s thermostat?Jason West, Professor of Environmental Sciences and Engineering, University of North Carolina at Chapel HillLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1214212019-08-25T18:32:21Z2019-08-25T18:32:21ZHow we can keep our planet cool even as A/C use rises<p>On June 28, 2019, record temperatures were recorded in the French department of <a href="http://www.meteofrance.fr/actualites/73726667-record-absolu-de-chaleur-battu-45-9-c-dans-le-gard-du-jamais-vu-en-france">le Gard</a>, rising above the 45°C (113°F) mark for the first time in France. Less than a month later a second heat wave hit, pushing temperatures in Paris and other cities to highs <a href="https://www.nytimes.com/2019/07/25/world/europe/heatwave-record-temperatures.html">never seen before</a>. </p>
<p>High temperatures are now plaguing many countries around the world, including India, which suffered <a href="https://www.parismatch.com/Actu/International/L-Inde-suffoque-sous-la-chaleur-jusqu-a-50-C-1627979">suffocating heat in June 2019</a>, with temperatures of more than 50°C (122°F).</p>
<p>Given the repeated heat waves, the use of air conditioning (A/C) has soared: it improves both living conditions and economic productivity. But the instant relief it offers is offset by its harmful environmental effects.</p>
<p>What are the trends in A/C use worldwide? What are its environmental impacts and what actions must we undertake to improve the situation? In order to answer these questions, we used data provided by Enerdata and a <a href="https://www.iea.org/futureofcooling/">2018 report</a> by the International Energy Agency (IEA).</p>
<h2>A booming economic activity</h2>
<p>Less than a third of households worldwide own an A/C unit, but some regions are more equipped than others. In the United States and in Japan, 90% of households have one. China now has over a third of the world’s A/C units, with a 60% household ownership rate – a ratio far above that of 8% for the 2.8 billion households living in the hottest regions. In Europe, on average, 20% of households own an A/C unit, but only 5% of French households do.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/287188/original/file-20190807-144878-ikkosx.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/287188/original/file-20190807-144878-ikkosx.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/287188/original/file-20190807-144878-ikkosx.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=181&fit=crop&dpr=1 600w, https://images.theconversation.com/files/287188/original/file-20190807-144878-ikkosx.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=181&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/287188/original/file-20190807-144878-ikkosx.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=181&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/287188/original/file-20190807-144878-ikkosx.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=227&fit=crop&dpr=1 754w, https://images.theconversation.com/files/287188/original/file-20190807-144878-ikkosx.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=227&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/287188/original/file-20190807-144878-ikkosx.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=227&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The air conditioning boom is a global phenomenon.</span>
<span class="attribution"><span class="source">Carine Sebi based on data from the AIE and Odyssee</span></span>
</figcaption>
</figure>
<p>Trends in A/C unit sales show that the gaps are closing. Sales rose 15% between 2017 and 2018, particularly in emerging economies (China, Brazil, India, Indonesia and Mexico), where extremely high temperatures are increasingly frequent. The number of A/C units in the world rose by 40%, and has almost doubled in Asia since 2010.</p>
<h2>Extremely rapid growth in energy consumption</h2>
<p>Air conditioning represents an increasingly large proportion of electricity consumption in the building sector, both residential and tertiary. It is responsible for 12% of the sector’s CO<sub>2</sub> emissions worldwide.</p>
<p>In Saudi Arabia, A/C accounts for 73% of the sector’s electricity consumption, as compared to 23% in the US and India. In Europe, it accounts for only 2%, but with a marked annual increase since 2000 (3.5% growth per annum), a rate that remains modest when compared to those observed in Asia: 12% per annum since 2000 in China, 11% in India and 9% in Indonesia.</p>
<p>Japan is an exception, with stable consumption since 2000: since the A/C market is almost completely saturated (with a 90% ownership rate), there is little change in the number of A/C units installed, and replacing old units with more efficient models improves their overall energy efficiency.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/287189/original/file-20190807-144883-8oj5c0.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/287189/original/file-20190807-144883-8oj5c0.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/287189/original/file-20190807-144883-8oj5c0.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=364&fit=crop&dpr=1 600w, https://images.theconversation.com/files/287189/original/file-20190807-144883-8oj5c0.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=364&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/287189/original/file-20190807-144883-8oj5c0.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=364&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/287189/original/file-20190807-144883-8oj5c0.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=457&fit=crop&dpr=1 754w, https://images.theconversation.com/files/287189/original/file-20190807-144883-8oj5c0.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=457&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/287189/original/file-20190807-144883-8oj5c0.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=457&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 high energy cost of cooling.</span>
<span class="attribution"><span class="source">Carine Sebi based on data from Enerdata</span></span>
</figcaption>
</figure>
<h2>Electrical systems tested to their limits</h2>
<p>At the peak of June’s heat wave in France, the French transmission system operator, RTE, announced that a record high for summer electricity consumption – 59,436 MW – had been reached due to increased use of A/C units and fans. They indicated that each degree above normal seasonal temperatures was correlated with additional electricity consumption equivalent to that of the <a href="https://www.francetvinfo.fr/meteo/canicule/canicule-le-pic-de-consommation-electrique-a-ete-atteint-jeudi-a-12h40_3510291.html">entire city of Bordeaux (around 250,000 inhabitants)</a>. In China, on the hottest days, A/C accounts for up to half of peak electricity demand in the country.</p>
<p>Cooling our living spaces now contributes to global warming. First, a large proportion of A/C units sold or installed worldwide are highly energy intensive. They consume large amounts of electricity, produced mainly using <a href="https://theconversation.com/comment-expliquer-la-hausse-de-la-consommation-de-charbon-dans-le-monde-110625">coal</a>, which results in high CO<sub>2</sub> emissions.</p>
<p>Unfortunately, the biggest users of A/C in the world are those with the most polluting energy mix, like Saudi Arabia and China. Although energy production in the US has a significantly lower carbon index than in these two countries, it still has the highest CO<sub>2</sub> emissions due to the amount of electricity generated to satisfy the demand for air conditioning. Trends indicate that this is a growing phenomenon. In China, CO<sub>2</sub> emissions linked to A/C use rose five-fold between 2000 and 2017.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/287192/original/file-20190807-144862-jcv1ct.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/287192/original/file-20190807-144862-jcv1ct.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/287192/original/file-20190807-144862-jcv1ct.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=183&fit=crop&dpr=1 600w, https://images.theconversation.com/files/287192/original/file-20190807-144862-jcv1ct.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=183&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/287192/original/file-20190807-144862-jcv1ct.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=183&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/287192/original/file-20190807-144862-jcv1ct.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=230&fit=crop&dpr=1 754w, https://images.theconversation.com/files/287192/original/file-20190807-144862-jcv1ct.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=230&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/287192/original/file-20190807-144862-jcv1ct.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=230&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">CO₂ emissions linked to electricity generation and A/C use.</span>
<span class="attribution"><span class="source">Carine Sebi based on data from Enerdata (left) and the AIE (right)</span></span>
</figcaption>
</figure>
<p>Air conditioners also use coolants, like refrigerants, with high global warming potential when released into the atmosphere. Some of these agents are up to several thousand times more warming than CO<sub>2</sub>. These gases are not supposed to be emitted by A/C units, but leakage often occurs during manufacturing, maintenance and breakdowns.</p>
<h2>Can we mitigate the harmful effects?</h2>
<p>It is, however, possible to slow certain harmful effects. First, it is important to de-carbonize the energy used by buildings, for which A/C represents an increasing proportion of energy consumption. The development of renewables worldwide should enable such de-carbonization. Second, it is imperative that architecture adapt to climate change, for both new (mostly in Asia) and existing (in Europe and North America) building stock. Insulation, appropriate building materials, and window protection against the sun are some of the solutions that can drastically reduce the need for A/C.</p>
<p>We must also remember that the energy efficiency of A/C units varies widely from one country to the next: equipment sold in Japan and the EU is generally 25% more efficient than that sold in the United States and China. Optimizing the energy consumption of A/C units, especially by implementing standards and obligatory energy efficiency labelling, could cut the increase in energy demand in half.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/283725/original/file-20190711-173360-ct7c1t.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/283725/original/file-20190711-173360-ct7c1t.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/283725/original/file-20190711-173360-ct7c1t.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=264&fit=crop&dpr=1 600w, https://images.theconversation.com/files/283725/original/file-20190711-173360-ct7c1t.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=264&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/283725/original/file-20190711-173360-ct7c1t.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=264&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/283725/original/file-20190711-173360-ct7c1t.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=332&fit=crop&dpr=1 754w, https://images.theconversation.com/files/283725/original/file-20190711-173360-ct7c1t.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=332&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/283725/original/file-20190711-173360-ct7c1t.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=332&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Improved energy efficiency for A/C units helped avoid a 20% increase in A/C energy consumption worldwide, as compared to 2000 levels.</span>
<span class="attribution"><span class="source">AIE</span></span>
</figcaption>
</figure>
<p>We also need stricter regulation for refrigerant fluids that have been in use for the past 30 years or so. The first generation of gas (chlorofluorocarbons or CFCs) was banned in 1981 in the <a href="https://www.canada.ca/en/environment-climate-change/corporate/international-affairs/partnerships-organizations/ozone-layer-depletion-montreal-convention.html">Montreal Protocol</a>, because of its destructive effects on the ozone layer.</p>
<p>The current generation of refrigerants (hydrofluorocarbons or HFCs) has little effect on the ozone layer but unfortunately contributes heavily to the greenhouse effect. The inclusion of HFCs in the Montreal Protocol was finally made official in November 2018, through the <a href="https://www.unenvironment.org/news-and-stories/press-release/world-takes-stand-against-powerful-greenhouse-gases-implementation">Kigali amendment</a>, which aims to reduce the use of HFCs by 80% between now and 2038-2047.</p>
<p>Within the EU, the <a href="https://ec.europa.eu/clima/policies/f-gas/legislation_en">F-gas regulation</a> was implemented in 2006, entirely replaced in 2015. This regulation aims to speed up a reduction in greenhouse gas emissions through a gradual ban on HFCs currently used in the cooling sector.</p>
<p>Finally, adopting good habits is an essential part of the solution and should allow us to reduce A/C consumption. The French Environment and Energy Management Agency, Ademe, advises that rooms <a href="https://www.ademe.fr/sites/default/files/assets/documents/guide-pratique-chaud-dehors-frais-dedans.pdf">not be cooled to under 26°C</a>. The difference between outside and inside temperatures should not be more than 5 to 7 degrees. This is also a way of reducing electricity bills, since an ambient temperature just <a href="https://conseils.xpair.com/consulter_savoir_faire/20-faits-optimiser-chauffage-climatisation/fait-13-climatisation-1-degre-trop-bas-surconsommation.htm">1°C too low</a> – for example, 23°C rather than 24°C – increases an A/C unit’s annual energy consumption by 12 to 18%.</p>
<h2>3.5 times more A/C units by 2050</h2>
<p>According to the IEA, the number of A/C units worldwide will rise from 1.6 billion to 5.6 billion by 2050. This increase is expected to be particularly high in emerging economies like India, where A/C could represent 45% of peak electricity demand by 2050, as opposed to the current 10%. Large investments in new electrical plants would be necessary to meet this peak demand during the night, when solar energy is unavailable.</p>
<p>Let us also hope that A/C manufacturers will find an alternative to refrigerant fluids. For now, the planned alternative is HFOs (hydrofluoroolefins), which have little greenhouse impact. However, one of the degradants produced by the breakdown of HFOs is <a href="https://www.multitanks.com/fr/blog/communique-de-presse-de-greenpeace-sur-les-gaz-hfo-n12">toxic to plants</a>, and remains in soils and water for long periods of time…</p>
<hr>
<p><em>Translated from the French by Alice Heathwood for <a href="http://www.fastforword.fr/en/">Fast ForWord</a>.</em></p><img src="https://counter.theconversation.com/content/121421/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Carine Sebi ne travaille pas, ne conseille pas, ne possède pas de parts, ne reçoit pas de fonds d'une organisation qui pourrait tirer profit de cet article, et n'a déclaré aucune autre affiliation que son organisme de recherche.</span></em></p>As our planet warms, the number of air-conditioning units worldwide is expected to triple by 2050 – yet their use drives climate change. So how can we break the cycle?Carine Sebi, Associate Professor and Coordinator of the "Energy for Society" Chair, Grenoble École de Management (GEM)Licensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1153552019-08-23T12:27:58Z2019-08-23T12:27:58ZWhy we need to get back to Venus<figure><img src="https://images.theconversation.com/files/288812/original/file-20190820-170918-m7ducg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">On June 5-6, 2012, NASA's Solar Dynamics Observatory collected images of one of the rarest predictable solar events: the transit of Venus across the face of the Sun. </span> <span class="attribution"><a class="source" href="https://www.nasa.gov/multimedia/imagegallery/image_feature_2271.html">NASA/SDO, AIA</a></span></figcaption></figure><p>Just next door, cosmologically speaking, is a planet <a href="https://space-facts.com/venus/">almost exactly like Earth</a>. It’s about the same size, is made of about the same stuff and formed around the same star. </p>
<p>To an alien astronomer light years away, observing the solar system through a telescope, it would be virtually indistinguishable from our own planet. But to know the <a href="https://www.businessinsider.com/what-venus-surface-is-like-2017-1">surface conditions</a> of Venus – the temperature of a self-cleaning oven, and an atmosphere saturated with carbon dioxide with sulfuric acid clouds – is to know that it’s anything but Earth-like.</p>
<p>So how is it that two planets so similar in position, formation and composition can end up so different? That’s a question that preoccupies an ever-growing number of planetary scientists, and motivates <a href="http://www.planetary.org/blogs/guest-blogs/van-kane/20171008-venus-origins-explorer-new-frontiers.html">numerous proposed Venus exploration efforts</a>. If scientists can understand why Venus turned out the way it did, we’ll have a better understanding of whether an Earth-like planet is the rule – or the exception.</p>
<p><a href="https://meas.sciences.ncsu.edu/people/pkbyrne">I’m a planetary scientist</a>, and I’m fascinated by how other worlds came to be. I’m particularly interested in Venus, because it offers us a glimpse of a world that once might not have been so different from our own.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/288793/original/file-20190820-170906-dr7spy.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/288793/original/file-20190820-170906-dr7spy.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=303&fit=crop&dpr=1 600w, https://images.theconversation.com/files/288793/original/file-20190820-170906-dr7spy.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=303&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/288793/original/file-20190820-170906-dr7spy.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=303&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/288793/original/file-20190820-170906-dr7spy.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=380&fit=crop&dpr=1 754w, https://images.theconversation.com/files/288793/original/file-20190820-170906-dr7spy.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=380&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/288793/original/file-20190820-170906-dr7spy.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=380&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The surface of Venus as seen in these reprocessed perspective image panoramas from the Soviet Venera 13 lander.</span>
<span class="attribution"><a class="source" href="http://mentallandscape.com/C_Venera_Perspective.jpg">Don P. Mitchell</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<h2>A once-blue Venus?</h2>
<p>The current scientific view of Venus holds that, at some point in the past, the planet had much more water than its bone-dry atmosphere suggests today <a href="https://climate.nasa.gov/news/2475/nasa-climate-modeling-suggests-venus-may-have-been-habitable/">– perhaps even oceans</a>. But as the Sun grew hotter and brighter (a natural consequence of aging), surface temperatures rose on Venus, eventually vaporizing any oceans and seas. </p>
<p>With ever more water vapor in the atmosphere, the planet entered a <a href="https://www.universetoday.com/22577/venus-greenhouse-effect/">runaway greenhouse</a> condition from which it couldn’t recover. Whether Earth-style plate tectonics (where the outer layer of the planet is broken into large, mobile pieces) ever operated on Venus is unknown. Water is critical for plate tectonics to operate, and a runaway greenhouse effect would effectively shut down that process had it operated there.</p>
<p>But the ending of plate tectonics wouldn’t have spelled the end of geological activity: The planet’s considerable internal heat continued to produce magma, which poured out as voluminous lava flows and resurfaced most of the planet. Indeed, the average surface age of Venus is around 700 million years – very old, certainly, but much younger than the multi-billion-year-old surfaces of Mars, Mercury or the Moon.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/288809/original/file-20190820-170922-2mqr0e.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/288809/original/file-20190820-170922-2mqr0e.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/288809/original/file-20190820-170922-2mqr0e.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/288809/original/file-20190820-170922-2mqr0e.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/288809/original/file-20190820-170922-2mqr0e.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/288809/original/file-20190820-170922-2mqr0e.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/288809/original/file-20190820-170922-2mqr0e.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">An artist’s impression of what a formerly water-rich Venus may have looked like.</span>
<span class="attribution"><a class="source" href="https://upload.wikimedia.org/wikipedia/commons/b/b9/TerraformedVenus.jpg">Daein Ballard</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<h2>The exploration of Planet 2</h2>
<p>The Venus-as-a-wet-world view is just a hypothesis: Planetary scientists don’t know what caused Venus to differ so much from Earth, nor even if the two planets really <em>did</em> start off with the same conditions. Humans know less about Venus than we do about the other inner solar system planets, largely because the planet poses several unique challenges to its exploration.</p>
<p>For example, <a href="https://insider.si.edu/2013/11/mapping-venus-with-radar/">radar</a> is needed to pierce the opaque, sulfuric acid clouds and see the surface. That’s a lot trickier than <a href="https://solarsystem.nasa.gov/planets/mercury/overview/">the readily visible surfaces of the Moon or Mercury</a>. And the high surface temperature – 470 degrees Celsius (880 degrees Fahrenheit) – means that conventional electronics don’t last more than a few hours. That’s a far cry from Mars, <a href="https://www.nasa.gov/press-release/nasas-record-setting-opportunity-rover-mission-on-mars-comes-to-end">where rovers can operate for more than a decade</a>. In part because of the heat, acidity and obscured surface, then, Venus hasn’t enjoyed a sustained program of exploration over the past couple of decades.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/288810/original/file-20190820-170956-1c0xbpk.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/288810/original/file-20190820-170956-1c0xbpk.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/288810/original/file-20190820-170956-1c0xbpk.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/288810/original/file-20190820-170956-1c0xbpk.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/288810/original/file-20190820-170956-1c0xbpk.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/288810/original/file-20190820-170956-1c0xbpk.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/288810/original/file-20190820-170956-1c0xbpk.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">Visible-wavelength light is unable to penetrate the thick cloud layer on Venus. Instead, radar is required to view the surface from space. This is a global radar image mosaic of the planet, compiled with data returned by the Magellan mission.</span>
<span class="attribution"><span class="source">SSV/MIPL/MAGELLAN TEAM/NASA</span></span>
</figcaption>
</figure>
<p>That said, there have been two dedicated Venus missions in the 21st century: the European Space Agency’s <a href="http://sci.esa.int/venus-express/">Venus Express</a>, which operated from 2006 to 2014, and the Japan Aerospace Exploration Agency’s <a href="http://akatsuki.isas.jaxa.jp/en/">Akatsuki spacecraft</a> <a href="https://www.nasa.gov/feature/nasa-scientists-applaud-japanese-spacecraft-akatsuki-s-successful-rendezvous-with-venus">currently in orbit </a>.</p>
<p>Humans haven’t always ignored Venus. It was once the darling of planetary exploration: between the 1960s and 1980s, some 35 missions were dispatched to the second planet. The NASA <a href="https://www.jpl.nasa.gov/missions/mariner-2/">Mariner 2 mission</a> was the first spacecraft to successfully carry out a planetary encounter when it flew past Venus in 1962. The first images returned from the surface of another world were sent from the Soviet <a href="https://nssdc.gsfc.nasa.gov/imgcat/html/object_page/v09_lander_proc.html">Venera 9 lander</a> after it touched down in 1975. And the <a href="https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1981-106D">Venera 13 lander</a> was the first spacecraft to return sounds from the surface of another world. But the last mission NASA launched to Venus was <a href="https://solarsystem.nasa.gov/missions/magellan/in-depth/">Magellan</a> in 1989. That spacecraft imaged almost the entire surface with radar before its planned demise in the planet’s atmosphere in 1994. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/288811/original/file-20190820-170935-1aa0t54.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/288811/original/file-20190820-170935-1aa0t54.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/288811/original/file-20190820-170935-1aa0t54.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/288811/original/file-20190820-170935-1aa0t54.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/288811/original/file-20190820-170935-1aa0t54.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/288811/original/file-20190820-170935-1aa0t54.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/288811/original/file-20190820-170935-1aa0t54.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">The Magellan mission was launched from Atlantis’ cargo bay on May 4, 1989. The spacecraft’s 3.7-m-diameter high gain antenna is visible at the top of the image.</span>
<span class="attribution"><span class="source">NASA</span></span>
</figcaption>
</figure>
<h2>Back to Venus?</h2>
<p>In the last few years, several NASA Venus missions have been proposed. The most recent planetary mission that NASA chose is a nuclear-powered craft called <a href="https://dragonfly.jhuapl.edu/">Dragonfly</a>, destined for Saturn’s moon Titan. However, one proposal to measure the composition of the Venus surface <a href="https://www.nasa.gov/press-release/nasa-invests-in-concept-development-for-missions-to-comet-saturn-moon-titan">was selected for further technology development</a>.</p>
<p>Other missions being considered include one by the ESA to <a href="https://envisionvenus.eu/envision/">map the surface at high resolution</a>, and a <a href="https://www.space.com/41986-venus-landing-mission-venera-d.html">Russian</a> <a href="https://www.space.com/41986-venus-landing-mission-venera-d.html">plan to build on its legacy</a> as the only country to successfully put a lander on Venus’ surface.</p>
<p>Some 30 years after NASA set course for our hellish neighbor, the future of Venus exploration looks promising. But a single mission – a radar orbiter or <a href="https://www.hou.usra.edu/meetings/lpsc2018/pdf/2796.pdf">even a long-lived lander</a> – won’t solve all the outstanding mysteries. </p>
<p>Rather, a sustained program of exploration is needed to bring our knowledge of Venus to where we understand it as well as Mars or the Moon. That will take time and money, but I believe it’s worth it. If we can understand why and when Venus came to be the way it is, we’ll have a better grasp of how an Earth-size world can evolve <a href="http://hzgallery.org/venus.html">when it’s close to its star</a>. And, under an ever-brightening Sun, Venus may even help us understand the fate of Earth itself.</p>
<p>[ <em>You’re smart and curious about the world. So are The Conversation’s authors and editors.</em> <a href="https://theconversation.com/us/newsletters?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=youresmart">You can read us daily by subscribing to our newsletter</a>. ]</p><img src="https://counter.theconversation.com/content/115355/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Paul K. Byrne 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>This hot, acidic neighbor with its surface veiled in thick clouds hasn’t benefited from the attention showered on Mars and the Moon. But Venus may offer insights into the fate of the Earth.Paul K. Byrne, Associate Professor of Planetary Science, North Carolina State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1168222019-08-06T04:55:30Z2019-08-06T04:55:30ZCurious Kids: why is air colder the higher up you go?<figure><img src="https://images.theconversation.com/files/277812/original/file-20190604-69095-wobo98.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C5068%2C3456&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The air up high is just really bad at 'holding' onto the radiation coming from the Sun, and the warmth passes straight through it on its journey toward the ground.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/vek/9401307943/">Kevin Spencer/flicr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span></figcaption></figure><figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=293&fit=crop&dpr=1 600w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=293&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=293&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=368&fit=crop&dpr=1 754w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=368&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=368&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p><em><a href="https://theconversation.com/us/topics/curious-kids-36782">Curious Kids</a> is a series for children of all ages. If you have a question you’d like an expert to answer, send it to <a href="mailto:curiouskidsus@theconversation.com">curiouskidsus@theconversation.com</a>.</em></p>
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<blockquote>
<p><strong>Why is air colder the higher up you go? Shouldn’t it be hotter as you’re getting closer to the Sun? – Flynn, age 6, Sydney.</strong></p>
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<hr>
<p>Thank you Flynn, that’s a great question. A lot of people have probably wondered this. </p>
<p>As you may know, hot air rises. So why is it so cold at the top of a mountain?</p>
<p>Well, it helps if you imagine the ground here on Earth as a big heater. It keeps us warm, and if you move away from the heater you feel cold.</p>
<p>So what “heats up” the heater? The light and warmth from the Sun. Scientists call this light and warmth “radiation”.</p>
<h2>Light and warmth travel from the Sun</h2>
<p>The light and warmth from the Sun travel through space towards Earth, and pass through our atmosphere. (The “atmosphere” is what we call the swirling air that surrounds our planet.)</p>
<p>But the atmosphere isn’t very good at holding onto the warmth from the Sun. The heat just slips straight through it. (For the adults reading: that’s because air at higher altitudes thins out as the gas particles expand and lose energy.)</p>
<p>Eventually, the heat from the Sun hits the ground and the ground soaks it up. This especially happens in forests and oceans, which are very good at absorbing heat. Other places, like snow fields, are more likely to reflect the radiation – meaning it bounces back toward the Sun instead of being soaked up by the ground.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/285033/original/file-20190722-116569-k5gskm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/285033/original/file-20190722-116569-k5gskm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/285033/original/file-20190722-116569-k5gskm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/285033/original/file-20190722-116569-k5gskm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/285033/original/file-20190722-116569-k5gskm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/285033/original/file-20190722-116569-k5gskm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/285033/original/file-20190722-116569-k5gskm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/285033/original/file-20190722-116569-k5gskm.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">The ocean and forests are especially good at soaking up and holding onto heat from the Sun.</span>
<span class="attribution"><span class="source">Pixabay/Stocksnap</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
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<h2>Up, up, up</h2>
<p>The higher up you go, the further you are away from the “heater” that is keeping us all warm – the ground that has absorbed the warmth from the Sun. At the top of mountains it can get so cold people could die within minutes without special protection. That’s because the air up there is just really bad at “holding onto” the radiation coming from the Sun, and the warmth passes straight through it on its journey toward the ground.</p>
<p>And all the way up in space, there is a lot more radiation from the Sun, and astronauts wear special suits to protect themselves from it. But there’s also no air in space, which means there’s really nothing much at all to “hold onto” the warmth of the Sun and make the temperature around you feel warm.</p>
<p>So if you were unlucky enough to be caught in space without a suit, you would freeze to death before the Sun’s radiation would get you.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/curious-kids-how-is-global-warming-heating-up-the-earth-117543">Curious Kids: how is global warming heating up the Earth?</a>
</strong>
</em>
</p>
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<img src="https://counter.theconversation.com/content/116822/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Zoran Ristovski has received a number of grants from the Australian Research Council (ARC) as well as other funding bodies.
</span></em></p><p class="fine-print"><em><span>Branka Miljevic receives funding from the Australian Research Council, the Australian Department of Education Endeavour Leadership program, the Australian Academy of Science and various internal QUT grants.
</span></em></p>It helps if you imagine the ground here on Earth as a big heater. It keeps us warm, and if you move away from the heater you feel cold.Zoran Ristovski, Professor, Queensland University of TechnologyBranka Miljevic, Senior Lecturer, Queensland University of TechnologyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1140212019-03-24T19:47:21Z2019-03-24T19:47:21ZHow humans derailed the Earth’s climate in just 160 years<figure><img src="https://images.theconversation.com/files/265071/original/file-20190321-93051-vim6mh.jpg?ixlib=rb-1.1.0&rect=16%2C21%2C3604%2C2453&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The exploitation of fossil fuels emits CO₂, the main cause of global warming.</span> <span class="attribution"><a class="source" href="https://unsplash.com/photos/GrmwVnVSSdU">Zbynek Burival/Unsplash</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>Climate change might be the most urgent issue of our day, both politically and in terms of life on Earth. There is mounting awareness that the global climate is a matter for public action. </p>
<p>For 11,500 years, atmospheric carbon dioxide (CO<sub>2</sub>) concentrations hovered around 280 ppm (the preindustrial “normal”), with an average surface temperature around 15°C. Since the Industrial Revolution, this level has been rising continuously, reaching 410 ppm in 2018. The geosciences, with their focus on timescales up to billions of years, are uniquely equipped to make extremely clear how abruptly industrial societies have changed and are changing the Earth’s climate.</p>
<h2>Climate, greenhouse gases and CO<sub>2</sub></h2>
<p>The main engine of Earth’s climate is the sun. Our star delivers an average surface power of 342 W/m<sup>2</sup> per year (roughly that of a hairdryer for each square meter of the planet). Earth absorbs about 70% of this and reflects the rest. If this were the only climate mechanism, the average temperature would be -15°C (below the freezing point of water, 0°C). Life would likely be impossible. Fortunately, some of the absorbed energy is re-emitted as infrared radiation, which, unlike visible light, interacts with the greenhouse gases (GHGs) present in the atmosphere to radiate heat back toward Earth’s surface. This greenhouse effect currently maintains our average temperature around 15°C.</p>
<p>The primary GHGs are water vapour and the much-debated CO<sub>2</sub>. Carbon dioxide contributes up to 30% of the total greenhouse effect, water vapour provides about 70%. CO<sub>2</sub>, though, has overall warming power that water vapour doesn’t. Water vapour in the atmosphere has a very short residence time (from hours to days) and its concentration can increase only if temperature increases. CO<sub>2</sub> lingers in the atmosphere for 100 years and its concentration is not solely controlled by temperature. CO<sub>2</sub> is thus able to <em>trigger</em> warming: if CO<sub>2</sub> concentration increases, the average temperature, regardless of its own trend, will increase.</p>
<h2>Carbon sinks</h2>
<p>It is thus crucial to understand how atmospheric CO<sub>2</sub> is regulated. Over geologic timescales (100,000+ years), volcanic gasses are the primary source of CO<sub>2</sub>, averaging 0.4 billion of tons of CO<sub>2</sub> per year (0.4 GtCO<sub>2</sub>/y). But CO<sub>2</sub> doesn’t just endlessly accumulate in the atmosphere. It fluxes in and out thanks to other environmental processes, and is stored in reservoirs known as carbon sinks.</p>
<p>The ocean, for one, contains <a href="https://serc.carleton.edu/integrate/teaching_materials/earth_modeling/student_materials/unit9_article1.html">50 times</a> more carbon than the atmosphere. However, CO<sub>2</sub> dissolved in the ocean can easily be released toward the atmosphere, while only geological sinks keep CO<sub>2</sub> away from the atmosphere on geological timescales.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/265086/original/file-20190321-93054-1tkx8bi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/265086/original/file-20190321-93054-1tkx8bi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/265086/original/file-20190321-93054-1tkx8bi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=659&fit=crop&dpr=1 600w, https://images.theconversation.com/files/265086/original/file-20190321-93054-1tkx8bi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=659&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/265086/original/file-20190321-93054-1tkx8bi.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=659&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/265086/original/file-20190321-93054-1tkx8bi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=829&fit=crop&dpr=1 754w, https://images.theconversation.com/files/265086/original/file-20190321-93054-1tkx8bi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=829&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/265086/original/file-20190321-93054-1tkx8bi.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=829&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Simplified geological carbon cycle. The sinks (black) show the sedimentation of organic matter and the alteration-synthesis coupling of carbonate. They oppose (grey) sources: volcanoes for more than 4 billion years and thermo-industrial human activities for 150 years.</span>
<span class="attribution"><span class="source">G. Paris</span></span>
</figcaption>
</figure>
<p>The first geological sink is sedimentary organic matter. Living organisms contain organic carbon built from atmospheric CO<sub>2</sub> through <a href="https://en.wikipedia.org/wiki/Photosynthesis">photosynthesis</a>, and dead organisms are often sent to the bottom of the ocean, lakes, and swamps. Immense amounts of organic carbon thus accumulate over time in marine and continental sediments, some of which are eventually transformed into fossil fuels (oil, gas and coal).</p>
<p>Calcareous rocks are the second geological carbon sink. Rocks such as granites or basalts are <a href="https://en.wikipedia.org/wiki/Weathering">weathered</a> by surface waters, washing calcium and bicarbonate ions away to the ocean. Marine organisms use these to build hard parts made of calcium carbonate. When deposited at the bottom of the ocean, calcium carbonate is eventually sequestered as limestone.</p>
<p>Depending on the estimates, these two sinks combined contain <a href="https://serc.carleton.edu/integrate/teaching_materials/earth_modeling/student_materials/unit9_article1.html">50,000 to 100,000 times</a> more carbon than the present atmosphere.</p>
<h2>The Earth’s atmosphere over time</h2>
<p>The amount of CO<sub>2</sub> in the Earth’s atmosphere has varied widely. Decades of research allow us to draw the main lines of the history beginning after the Earth was fully formed <a href="https://www.sciencedirect.com/science/article/pii/S0016703718304666">4.4 billion years ago</a>.</p>
<p>Earth’s <a href="http://www.csun.edu/%7Ehmc60533/CSUN_311/article_references/Sc_Feb93_EarthEarlyAtmos.pdf">early atmosphere</a> was extremely rich in CO<sub>2</sub> (up to 10,000 times modern levels), while oxygen (O<sub>2</sub>) was scarce. During the Archean (3.8 to 2.5 billion years ago), life first flourished, the first continents built up. Weathering started pulling CO<sub>2</sub> out of the atmosphere. The development of photosynthesis contributed to decrease atmospheric CO<sub>2</sub>, while elevating O<sub>2</sub> levels during the <a href="https://www.origins.asu.edu/blog/oxygenation-catastrophe">Great Oxygenation Event</a>, about 2.3 billion years ago. CO<sub>2</sub> concentration fell to “only” 20 to 100 times the preindustrial level, never to return to the concentration of Earth’s earliest eons.</p>
<p>Two billion years later, the carbon cycle changed. Toward the late Devonian-early Carboniferous (<a href="http://scotese.com/newpage4.htm">approximately 350 million years ago</a>), CO<sub>2</sub> concentration was around <a href="http://www.atmo.arizona.edu/students/courselinks/spring08/atmo336s1/courses/fall07/atmo551a/pdf/CarbonCycle.pdf">1,000 ppm</a>. Mammals didn’t exist. Vascular plants able to synthesise lignin appeared during the Devonian and spread. <a href="https://en.wikipedia.org/wiki/Lignin">Lignin</a> is a molecule resistant to microbial degradation that allowed massive organic carbon stocks to build up as coal over millions of years. Combined with the weathering of the Hercynian range (the vestiges of which can be found in France’s Massif Central or the Appalachians in the United States), organic carbon burial pulled atmospheric CO<sub>2</sub> down to levels similar to (or lower than) today’s and generated a <a href="https://www.geolsoc.org.uk/Plate-Tectonics/Chap1-Pioneers-of-Plate-Tectonics/Alfred-Wegener/Glacial-Deposits-from-Permo-Carboniferous-Glaciation">major glacial era</a> between 320 and 280 million years ago.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/261316/original/file-20190227-150721-jqckwr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/261316/original/file-20190227-150721-jqckwr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/261316/original/file-20190227-150721-jqckwr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/261316/original/file-20190227-150721-jqckwr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/261316/original/file-20190227-150721-jqckwr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/261316/original/file-20190227-150721-jqckwr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/261316/original/file-20190227-150721-jqckwr.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">Eruption of Bromo volcano on the island of Java (2011). On a geological time scale, volcanoes play a role in the CO₂ cycle.</span>
<span class="attribution"><a class="source" href="https://unsplash.com/photos/IzoQu5vH47o">Marc Szeglat/Unsplash</a></span>
</figcaption>
</figure>
<p>By the end of the Jurassic (145 million years ago), however, the pendulum had swung. Dinosaurs ruled the Earth, mammals evolved, tectonic activity increased and Pangea (the last super-continent) <a href="http://scotese.com/jurassic.htm">ripped apart</a>. CO<sub>2</sub> increased, to <a href="https://websites.pmc.ucsc.edu/%7Ejzachos/pubs/H%25f6nisch_etal_2012.pdf">500 to 2,000 ppm</a>, and remained at high levels, maintaining a warm greenhouse climate for 100 million years.</p>
<p>From 55 million years, Earth cooled as CO<sub>2</sub> <a href="https://websites.pmc.ucsc.edu/%7Ejzachos/pubs/H%25f6nisch_etal_2012.pdf">decreased</a>, notably following the Himalayan uplift and a subsequent increase in weathering and organic carbon sedimentation. Evolution continues with Hominids appearing <a href="https://www2.palomar.edu/anthro/hominid/australo_1.htm">7 million years ago</a>. At 2.6 million years, Earth entered a new state characterised by an alternation of glacial and interglacial periods at a regular pace led by Earth’s orbital parameters and amplified by the shorter-term carbon cycle. CO<sub>2</sub> reached its preindustrial level 11,500 years ago as Earth entered the latest interglacial stage.</p>
<h2>A new story: the Industrial Revolution</h2>
<p>Until the 19th century, the story of atmospheric carbon and Earth’s climate was a story of geology, biology and evolution. That story changed sharply following the Industrial Revolution, when modern humans (<em>Homo sapiens</em>), who probably appeared <a href="http://science.sciencemag.org/content/358/6363/652">300,000 years ago</a>, began extracting and burning fossil fuels on a massive scale.</p>
<p>By 1950, the addition of CO<sub>2</sub> to the atmosphere through fossil-fuel combustion was already <a href="http://science.sciencemag.org/content/122/3166/415.2">proven</a>, via the <a href="https://en.wikipedia.org/wiki/Isotopes_of_carbon">carbon isotopic signature</a> of CO<sub>2</sub> molecules (known as the <a href="https://en.wikipedia.org/wiki/Suess_effect">“Suess” effect</a>). By the late 1970’s, climate scientists observed a <a href="https://www.nytimes.com/interactive/2018/08/01/magazine/climate-change-losing-earth.html">rapid drift toward warmer overall temperatures</a>. The IPCC, created in 1988, showed in 2012 that the average temperature had increased by 0.9°C <a href="https://www.ipcc.ch/report/ar5/wg1/observations-atmosphere-and-surface/">since 1901</a>. That change might seem modest compared to the last deglaciation, when average temperature increased by about 6°C in 7,000 years, but it’s at least 10 times faster. </p>
<p>The average temperature continues to climb, and natural parameters such as solar activity or volcanism can’t explain such a fast warming. The cause is unambiguously human addition of GHGs to the atmosphere, and <a href="https://data.worldbank.org/indicator/EN.ATM.CO2E.PC?contextual=aggregate&end=2014&locations=XD-XM-XP-1W&name_desc=false&start=1960">high-income countries</a> emit the most CO<sub>2</sub> per inhabitant.</p>
<h2>How will our story end?</h2>
<p>Industrial societies burnt about 25% of Earth’s fossil fuels within 160 years and abruptly inverted a natural flux storing carbon away from the atmosphere. This new human-generated flux is instead <em>adding</em> <a href="https://cdiac.ess-dive.lbl.gov/trends/emis/tre_glob_2014.html">28 Gt of CO₂ per year</a>, 50 times more than volcanoes. Natural geological sequestration cannot compensate and atmospheric CO<sub>2</sub> keeps rising.</p>
<p>The <a href="https://www.ipcc.ch/sr15/graphics/">consequences</a> are imminent, numerous and dire: extreme weather events, sea-level rise, glacier retreat, ocean acidification, ecosystem disruptions and extinctions. Earth itself has survived other catastrophes. Although current warming will outpace many species’ ability to adapt, life will continue. It is not the planet that is at stake. Instead, it is the future of human societies and the preservation of current ecosystems.</p>
<p>While the Earth sciences cannot provide solutions to think about the necessary changes in our behaviour and consumption of fossil fuels, they can and must contribute to knowledge and collective awareness of the current global warming.</p>
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<p><em>We thank <a href="https://twitter.com/morganfahey">Morgan Fahey</a> for her invaluable help with the English text.</em></p><img src="https://counter.theconversation.com/content/114021/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Guillaume Paris received funding for his research from the CNRS, the University of Lorraine and the Agence Nationale de la Recherche.</span></em></p><p class="fine-print"><em><span>Pierre-Henri Blard received funding for his research from the University of Lorraine, the CNRS and the Agence Nationale de la Recherche.</span></em></p><p class="fine-print"><em><span>Etienne Deloule received funding for his research from the CNRS, the University of Lorraine, the Lorraine region and then the Grand Est region, the National Research Agency (ANR) and European programmes. He collaborates on research projects with Orano and Total.</span></em></p>The Earth’s past shows the key role of CO₂ on climate for 4.45 billion years, and how human industrial activity has disrupted its cycle at an unprecedented rate over the past 160 years.Guillaume Paris, Géochimiste, chargé de recherche CNRS au Centre de recherches pétrographiques et géochimiques de Nancy, Université de LorrainePierre-Henri Blard, Géochronologue et paléoclimatologue, chargé de recherches CNRS - Centre de recherches pétrographiques et géochimiques (Nancy) et Laboratoire de glaciologie (Bruxelles), Université de LorraineLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/909062018-03-20T10:42:20Z2018-03-20T10:42:20ZOn his 250th birthday, Joseph Fourier’s math still makes a difference<figure><img src="https://images.theconversation.com/files/210406/original/file-20180314-113479-1gr7sz8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Fourier's name is inscribed on the Eiffel Tower.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/philmciver/1018062764">philmciver/flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span></figcaption></figure><p>March 21 marks the 250th birthday of one of the most influential
mathematicians in history. He accompanied Napoleon on
his expedition to Egypt, revolutionized science’s understanding of
heat transfer, developed the mathematical tools used today to create
CT and MRI scan images, and discovered the greenhouse effect.</p>
<p>His name was Joseph Fourier. He <a href="https://ebooks.adelaide.edu.au/f/fourier/joseph/heat/preliminary.pdf">wrote</a> of mathematics: “There cannot be a language more universal and more simple, more free from errors and obscurities … Mathematical analysis is as extensive as nature itself, and it defines all perceptible relations.” Fourier’s work continues to shape life today, especially for people like ourselves working in fields such as mathematics and radiology.</p>
<h2>Fourier’s life</h2>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/210404/original/file-20180314-113465-aqizfg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/210404/original/file-20180314-113465-aqizfg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/210404/original/file-20180314-113465-aqizfg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=734&fit=crop&dpr=1 600w, https://images.theconversation.com/files/210404/original/file-20180314-113465-aqizfg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=734&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/210404/original/file-20180314-113465-aqizfg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=734&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/210404/original/file-20180314-113465-aqizfg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=923&fit=crop&dpr=1 754w, https://images.theconversation.com/files/210404/original/file-20180314-113465-aqizfg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=923&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/210404/original/file-20180314-113465-aqizfg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=923&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Mathematician and physicist Joseph Fourier.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Fourier2.jpg">Wikimedia Commons</a></span>
</figcaption>
</figure>
<p>As a <a href="http://www-groups.dcs.st-and.ac.uk/history/Biographies/Fourier.html">troubled orphan</a> in France, Fourier was transformed by his first encounter with mathematics. Thanks to a local bishop who recognized his talent, Fourier received an education through Benedictine monks. As a college student, he so loved math that he collected discarded candle stumps so he could continue his studies after others had gone to bed.</p>
<p>As a young man, Fourier was soon swept up by the French Revolution. However, he became disenchanted by its excessive brutality, and his protests landed him in prison for part of 1794. After his release, he was appointed to the faculty of an engineering school. There he proved his genius by substituting for ill colleagues, teaching subjects ranging from physics to classics.</p>
<p>Traveling with Napoleon to Egypt in 1798, Fourier was appointed secretary of the <a href="https://napoleon.lindahall.org/institute_of_egypt.shtml">Egyptian Institute</a>, which Napoleon modeled on the Institute of France. When the British fleet stranded the French forces, he organized the manufacture of weapons and munitions to permit the French to continue fighting. Fourier returned to France after the British navy forced the French to surrender. Even in the midst of such difficult circumstances, he managed to publish a number of mathematical papers. </p>
<h2>Heat transfer</h2>
<p>One of the most important fruits of Fourier’s studies concerns heat. </p>
<p><a href="http://www.thermopedia.com/content/781/">Fourier’s law</a> states that heat transfers through a material at a rate proportional to both the difference in temperature between different areas and to the area across which the transfer takes place. For example, people who are overheated can cool off quickly by getting to a cool place and exposing as much of their body to it as possible.</p>
<p>Fourier’s work enables scientists to predict the future distribution of heat. Heat is transferred through different materials at different rates. For example, brass has a high <a href="https://www.engineeringtoolbox.com/thermal-conductivity-d_429.html">thermal conductivity</a>. Air is poorly conductive, which is why it’s frequently used in insulation.</p>
<p>Remarkably, Fourier’s equation applies widely to matter, whether in the form of solid, liquid or gas. It powerfully shaped scientists’ understanding of both electricity and the process of diffusion. It also <a href="http://onlinelibrary.wiley.com/doi/10.1029/1998RG900006/full">transformed</a> scientists’ understanding of flow in nature generally – from water’s passage through porous rocks to the movement of blood through capillaries.</p>
<h2>Fourier transform and CT</h2>
<p>Today, when helping to care for patients, radiologists rely on another mathematical discovery of Fourier’s, now referred to as the “Fourier transform.”</p>
<p>In <a href="http://www.dspguide.com/ch25/5.htm">CT scans</a>, doctors send X-ray beams through a patient from multiple different directions. Some X-rays emerge from the other side, where they can be measured, while others are blocked by structures within the body.</p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/209937/original/file-20180312-30979-ljnc5k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/209937/original/file-20180312-30979-ljnc5k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/209937/original/file-20180312-30979-ljnc5k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/209937/original/file-20180312-30979-ljnc5k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/209937/original/file-20180312-30979-ljnc5k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/209937/original/file-20180312-30979-ljnc5k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/209937/original/file-20180312-30979-ljnc5k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/209937/original/file-20180312-30979-ljnc5k.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">Modern medical imaging machines rely on Fourier’s transform.</span>
<span class="attribution"><span class="source">zlikovec/shutterstock.com</span></span>
</figcaption>
</figure>
<p>With many such measurements taken at many different angles, it becomes possible to determine the degree to which each tiny block of tissue blocked the beam. For example, bone blocks most of the X-rays, while the lungs block very little. Through a complex series of computations, it’s possible to reconstruct the measurements into two-dimensional images of a patient’s internal anatomy. </p>
<p>Thanks to Fourier and <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2963745/">today’s powerful computers</a>, doctors can create almost instantaneous images of the brain, the pulmonary arteries, the appendix and other parts of the body. This in turn makes it possible to confirm or rule out the presence of issues such as blood clots in the pulmonary arteries or inflammation of the appendix. It’s difficult to imagine practicing medicine today without such CT images.</p>
<h2>Greenhouse effect</h2>
<p>Fourier is generally regarded as the <a href="https://history.aip.org/climate/co2.htm">first scientist</a> to notice what we today call the greenhouse effect. </p>
<p>His interest was piqued when he observed that a planet as far away from the sun as Earth should be considerably cooler. He hypothesized that something about the Earth – in particular, its atmosphere – must enable it to trap solar radiation that would otherwise simply radiate back out into space.</p>
<p>Fourier <a href="http://www.phys.ufl.edu/%7Ebernard/met1010_S05/warming.pdf">created a model</a> of the Earth involving a box with a glass cover. Over time, the temperature in the box rose above that of the surrounding air, suggesting that the glass continually trapped heat. Because his model resembled a greenhouse in some respects, this phenomenon came to be called the “greenhouse effect.” </p>
<p>Later, scientist John Tyndall <a href="http://www.rigb.org/our-history/iconic-objects/iconic-objects-list/tyndall-radiant-heat">discovered</a> that carbon dioxide can play the role of heat trapper.</p>
<p>Life on earth as we know it would not be possible without the greenhouse effect. However, today scientists tend to be more concerned about <a href="http://whrc.org/publications-data/understanding-climate-change-a-primer/">an excess of greenhouse gases</a>. Mathematical models suggest that as carbon dioxide accumulates, heat may be trapped more quickly, resulting in elevated global average temperatures, melting polar ice caps and rising sea levels.</p>
<h2>Fourier’s impact</h2>
<p>Fourier received many <a href="https://www.aps.org/publications/apsnews/201003/physicshistory.cfm">honors</a> during his lifetime, including election to the French Academy of Science.</p>
<p>Some believed, perhaps speciously, that Fourier’s attraction to heat may have hastened his death. <a href="http://lpsa.swarthmore.edu/Fourier/Series/FourierBio.html">He was known</a> to climb into saunas in multiple layers of clothes, and his acquaintances claimed that he kept his rooms hotter than Hades. At any rate, in May 1830, he died of an aneurysm at the age of 63. </p>
<p>Today, Fourier’s name is inscribed on the Eiffel Tower. But more importantly, it is immortalized in Fourier’s law and the Fourier transform, enduring emblems of his belief that mathematics holds the key to the universe.</p>
<p><em>This article has been updated to correct the year that Fourier traveled to Egypt.</em></p><img src="https://counter.theconversation.com/content/90906/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>Fourier’s discoveries can still be felt in modern-day radiology, climate science and physics.Richard Gunderman, Chancellor's Professor of Medicine, Liberal Arts, and Philanthropy, Indiana UniversityDavid Gunderman, PhD student in Applied Mathematics, University of Colorado BoulderLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/880782017-12-13T19:08:11Z2017-12-13T19:08:11ZIt’s official: 2016’s Great Barrier Reef bleaching was unlike anything that went before<p>It is no longer news that the Great Barrier Reef has suffered <a href="https://theconversation.com/how-much-coral-has-died-in-the-great-barrier-reefs-worst-bleaching-event-69494">extreme bleaching</a>. </p>
<p>In early 2016, we heard that the reef had suffered the worst bleaching ever recorded. <a href="https://www.nature.com/articles/nature21707">Surveys published in June that year</a> estimated that 93% of coral on the vast northern section of the reef was bleached, and 22% had already been killed. </p>
<p><a href="https://theconversation.com/year-on-year-bleaching-threatens-great-barrier-reefs-world-heritage-status-74606">Further reports from this year</a> show that bleaching again occurred. The back-to-back bleaching hit more than two-thirds of the Great Barrier Reef and may <a href="https://theconversation.com/the-great-barrier-reef-isnt-listed-as-in-danger-but-its-still-in-big-trouble-80681">threaten its UNESCO World Heritage listing</a>. </p>
<p>After recent years of damage, what does the future hold for our priceless reef? </p>
<p>Our <a href="http://www.ametsoc.net/eee/2016/ch28.pdf">new research</a>, published in the Bulletin of the American Meteorological Society’s <a href="https://www.ametsoc.org/ams/index.cfm/publications/bulletin-of-the-american-meteorological-society-bams/explaining-extreme-events-from-a-climate-perspective/">special report on climate extremes</a>, shows the news isn’t good for the Great Barrier Reef’s future. </p>
<hr>
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<strong>
Read more:
<a href="https://theconversation.com/how-to-work-out-which-coral-reefs-will-bleach-and-which-might-be-spared-84842">How to work out which coral reefs will bleach, and which might be spared</a>
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<p>Coral reefs are complex ecosystems that are affected by many factors. Changes in sea surface temperatures, rainfall, cloudiness, agricultural runoff, or <a href="https://theconversation.com/cloudy-issue-we-need-to-fix-the-barrier-reefs-murky-waters-39380">water quality</a> can affect a reef’s health and <a href="https://theconversation.com/au/topics/great-barrier-reef-threats-series-17189">resilience to stress</a>. </p>
<p><a href="https://theconversation.com/great-barrier-reef-bleaching-would-be-almost-impossible-without-climate-change-58408">Early analysis</a> of the 2016 bleaching suggested that the Great Barrier Reef was suffering from thermal stress brought on by human-caused climate change. </p>
<p>Our study took a new and comprehensive approach to examine these multiple climatic and environmental influences.</p>
<p>We set out to answer the crucial question: could anything else have bleached the Great Barrier Reef, besides human-induced climate change? </p>
<h2>Clear fingerprint</h2>
<p>The results were clear. Using a suite of climate models, we found that the significant warming of the Coral Sea region was likely caused by greenhouse gases from human activities. This warming was the primary cause of the extreme 2016 bleaching episode. </p>
<p>But what about those other complex factors? The 2016 event coincided with an El Niño episode that was <a href="https://theconversation.com/el-nino-is-over-but-has-left-its-mark-across-the-world-59823">among the most severe ever observed</a>. The <a href="https://theconversation.com/explainer-el-nino-and-la-nina-27719">El Niño-Southern Oscillation system</a>, with its positive El Niño and negative La Niña phases, has been linked to bleaching of various coral reefs in the past. </p>
<p>Our study showed that although the 2016 El Niño probably also contributed to the bleaching, this was a secondary contributor to the corals’ thermal stress. The major factor was the increase in temperatures because of climate change. </p>
<p>We next analysed other environmental data. <a href="https://link.springer.com/article/10.1007/s00338-015-1350-7">Previous research</a> has found that corals at sites with better water quality (that is, lower concentrations of pollution particles) are more resilient and less prone to bleaching. </p>
<p>Pollution data used in our study show that water quality in 2016 may have been better than in previous bleaching years. This means that the Great Barrier Reef should have been at lower risk of bleaching compared to long-term average conditions, all else being equal. Instead, record bleaching hit the reef as a result of the warming temperature trend. </p>
<h2>Previous events</h2>
<p>The final part of our investigation involved comparing the conditions behind the record 2016 bleaching with those seen in previous mass bleaching episodes on the Great Barrier Reef, in 1997-98 and 2010-11.</p>
<p>When we analysed these previous events on the Reef, we found very different factors at play. </p>
<p>In 1997-98 the bleaching coincided with a <a href="https://celebrating200years.noaa.gov/magazine/enso/el_nino.html">very strong El Niño event</a>. Although an El Niño event also occurred in 2016, the two were very different in terms of the distribution of unusually warm waters, particularly in the eastern equatorial Pacific. In 1997-98, the primary cause of the bleaching – which was less severe than in 2016 – was El Niño. </p>
<p>In 2010-11, the health of the Great Barrier Reef was impaired by runoff. That summer brought <a href="http://www.bom.gov.au/climate/current/annual/aus/2011/">record high rainfall to eastern Australia</a>, causing widespread flooding across Queensland. As a result of the discharge of freshwater onto the reef reducing the salinity, bleaching occurred. </p>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/feeling-helpless-about-the-great-barrier-reef-heres-one-way-you-can-help-76014">Feeling helpless about the Great Barrier Reef? Here's one way you can help</a>
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<p>There have been many reports in recent years warning of trouble for the Great Barrier Reef. Sadly, our study is yet another warning about the reef’s future – perhaps the most comprehensive warning yet. It tells us that the 2016 bleaching differed from previous mass bleaching events because it was driven primarily by human-induced climate warming.</p>
<p>This puts the Great Barrier Reef in grave danger of future bleaching from further greenhouse warming. The local environmental factors that have previously helped to protect our reefs, such as good water quality, will become less and less able to safeguard corals as the oceans warm. </p>
<p>Now we need to take immediate action to reduce greenhouse gas emissions and limit further warming. Without these steps, there is simply no future for our Great Barrier Reef.</p><img src="https://counter.theconversation.com/content/88078/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Sophie Lewis receives funding from the Australian Research Council. </span></em></p><p class="fine-print"><em><span>Jennie Mallela receives funding from The Australian Research Council and the Australian National University. </span></em></p>The 2016 bleaching on the Great Barrier Reef was the worst on record. Now a new analysis points the finger squarely at human-induced warming, and warns that the entire reef’s future is at stake.Sophie Lewis, Research fellow, Australian National UniversityJennie Mallela, Research Fellow in Coral Reef Monitoring and Reef Health Appraisal, Australian National UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/791492017-06-26T04:27:09Z2017-06-26T04:27:09ZHow the gas industry can help fight climate change in Siberia<figure><img src="https://images.theconversation.com/files/175489/original/file-20170625-13450-bu1b0d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Scientists monitor landscapes like Omulyakhskaya and Khromskaya Bays in northern Siberia closely.
</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/gsfc/6049749461">NASA Goddard Space Flight Center/flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>Permafrost is the layer of permanently frozen earth – <a href="https://robertscribbler.com/2017/03/24/from-canada-to-siberia-permafrost-thaw-produces-hells-mouth-craters-sinking-lands-and-7000-methane-pockets-waiting-to-blow/">over a 1,000 metres thick</a> in some places – that lies just beneath the land surface in Arctic regions. It formed over the past few million years when ice ages predominated. </p>
<p>Now, under the influence of global warming, it is melting. And <a href="https://theconversation.com/methane-and-the-risk-of-runaway-global-warming-16275">research</a> suggests that this may have reached the point of triggering runaway climate change, unless we can find ways to intervene.</p>
<p>The problem is that permafrost contains huge amounts of methane, anatural gas that’s being progressively released as the ice melts. Methane is a powerful greenhouse gas, having <a href="http://onlinelibrary.wiley.com/wol1/doi/10.1002/ese3.35/full">up to 80</a> times more warming potential than carbon dioxide. </p>
<p>We can’t stop this process, but could we capture the methane as it is released? It just so happens that the gas industry has the technology to do just this, and join the fight against climate change.</p>
<h2>Trouble on the tundra</h2>
<p>Scientists working in northern Siberia <a href="http://siberiantimes.com/science/casestudy/news/n0905-7000-underground-gas-bubbles-poised-to-explode-in-arctic/">announced in March this year</a> that they had identified some 7,000 small hillocks created by methane that has been released underground and is pushing the ground upwards. The hillocks are between 50 and 100 metres across.</p>
<p>In 2014, scientists also started discovering strange craters in the landscape, which appear to have been formed as a result of explosions. It seems that the pressure inside the hillocks builds up until a huge methane bubble is released with explosive force. These violent gas releases are dangerous to people and infrastructure, and scientists are working on ways of estimating the local threat. </p>
<p>Similar mounds have been discovered in the shallow waters off the Siberian shelf, and in <a href="http://siberiantimes.com/science/casestudy/features/f0183-leaking-pingos-can-explode-under-the-sea-in-the-arctic-as-well-as-on-land/">1995</a> a drilling vessel accidentally drilled into one, releasing a vast bubble of methane that almost sank the vessel.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"669504098245419009"}"></div></p>
<p>These releases have global consequences. They are a massive new source of greenhouse gas, making runaway climate change more likely. And there’s something that the gas industry could do about it. </p>
<h2>The right kind of mining</h2>
<p>The industry is already experienced in collecting coal seam and shale gas from large numbers of widely distributed, relatively small wells. It should be possible to use the same technology to tap into these massive gas bubbles before they burst, collect the methane and transport it to market. </p>
<p>If this turns out not to be commercially viable, internationally funded subsidies may be needed to provide an incentive to the gas industry. </p>
<p>If there is no prospect at all of marketing the gas, at least it could be flared - burnt - converting methane into CO₂ This would be far better <a href="http://onlinelibrary.wiley.com/wol1/doi/10.1002/ese3.35/full">environmentally</a> than allowing the methane to escape. But it would need to be fully funded by governments. </p>
<p>Petroleum companies, meanwhile, are considering mining reserves of frozen methane that lie far below the surface of the Arctic, and that are unlikely to be released by natural processes in the foreseeable future. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/175399/original/file-20170623-17464-a4oqzs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/175399/original/file-20170623-17464-a4oqzs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/175399/original/file-20170623-17464-a4oqzs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/175399/original/file-20170623-17464-a4oqzs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/175399/original/file-20170623-17464-a4oqzs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/175399/original/file-20170623-17464-a4oqzs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/175399/original/file-20170623-17464-a4oqzs.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">Harvesting arctic methane.</span>
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</figure>
<p>In order to be exploitable, these stable reserves need to be stimulated in various ways, such as by pumping hot water underground. But if gas producers were to focus on these <em>stable</em> reserves of methane, they would <em>contribute</em> to climate change rather than help combat it. </p>
<p>Any scheme to encourage gas companies to take up the challenge identified here would need to guard against this possibility.</p>
<h2>And now the sea bed</h2>
<p>A second type of methane release has also been <a href="http://siberiantimes.com/ecology/others/news/n0760-arctic-methane-gas-emission-significantly-increased-since-2014-major-new-research/">discovered</a>, coming from the Arctic seabed. The area is shallow, with an average depth of 50 metres, and was once dry land. At that time, it froze to great depth. </p>
<p>Now beneath the sea, it is thawing in particular spots known as <em>taliks</em>. </p>
<p>The result is that areas of the sea floor – some about a 100 metres across and others up to a kilometre across – are releasing streams of small methane bubbles that are rising to the surface in continuous fountains, and escaping into the atmosphere. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"784385451620757504"}"></div></p>
<p>Russian scientists have been monitoring these releases for several years and their most recent research, <a href="http://siberiantimes.com/ecology/others/news/n0760-arctic-methane-gas-emission-significantly-increased-since-2014-major-new-research/">published in late 2016 </a>, shows that the area from which this seepage is occurring has expanded. </p>
<p>They conclude that the rate of permafrost degeneration may have increased. They also note that the amount of methane being released from the Arctic seabed is comparable with that being released from the tundra.</p>
<p>For the continuous fountains of methane being released from the Arctic seabed, it should be possible to place domes over the escaping gas and bring it to the surface in a controlled fashion. </p>
<p>The gas industry already has <a href="https://www.google.com/patents/WO2015065412A1?cl=en">the technology to do this</a>. But this technology aims to stimulate the release of methane that might not otherwise be released. </p>
<p>Again, this would be counterproductive from an environmental point of view. So again, if the industry were to receive a subsidy for harvesting methane in this way and transporting it to market, or at the very least flaring it, controls would need to be in place to ensure that no additional methane was being harvested beyond that which would have been released in the normal course of events. </p>
<p>It’s now widely believed that even if human emissions of greenhouse gasses could be reduced to zero in the near future, it wouldn’t be enough to prevent catastrophic global warming. One of the additional steps we need to take is to curtail naturally occurring emissions. </p>
<p>Given the rate of technological change occurring in the renewable energy industry, the role of gas as a transition fuel may not last as long as the industry hopes. But if it can find a way to harvest methane escaping from the melting permafrost, it will have assured itself a longer term future. </p>
<p>The Paris Climate Summit envisaged developed countries finding US$100 billion a year to subsidise the efforts of developing countries to reduce greenhouse emissions. If that kind of money could be found to fund the capture of Arctic methane emissions, then the projects sketched above could become feasible.</p><img src="https://counter.theconversation.com/content/79149/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Andrew Hopkins does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>By capturing Arctic methane emissions, the gas industry could join the fight against climate change.Andrew Hopkins, Emeritus Professor of Sociology, Australian National UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/783632017-05-30T12:32:56Z2017-05-30T12:32:56ZVenus has very few volcanoes – weirdly, this might be why it’s as hot as hell<figure><img src="https://images.theconversation.com/files/171352/original/file-20170529-25201-1hlmaaj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/3d-renderingvenus-resolution-best-quality-solar-580798888?src=cvbKNLlwMuWNBXqY1Qi-cg-3-90">MAX3D</a></span></figcaption></figure><p>In the quest to discover habitable planets, scientists look for qualities similar to those of Earth. We do this because Earth sustains life, of course, but it falls down when you consider Venus. Based on size, chemistry and position in the solar system, our neighbouring planet is the most Earth-like ever observed. Yet while Earth is the definition of habitable, the planet Venus is a barren, hot, hellish wasteland. </p>
<p>Geologists like myself are trying to understand why two almost identical planets became so different. This is one way we can assist the astrophysics community in the exciting hunt for habitable exoplanets. A key part of the puzzle is understanding the interplay between plate tectonics and volcanoes, since <a href="https://theconversation.com/how-the-air-we-breathe-was-created-by-earths-tectonic-plates-33278">this governs</a> the <a href="https://www.nature.com/ngeo/journal/v10/n5/full/ngeo2939.html">chemistry</a> of the air that supports life. </p>
<p>I have been part of a research collaboration to look at Venus’ volcanic history, the results of which have <a href="http://www.sciencedirect.com/science/article/pii/S0031920116301418">just been published</a> in the journal Physics of the Earth and Planetary Interiors. This study sheds some valuable light on the volcanic history of Earth’s sibling, and indirectly speaks towards how Venus became so hot in the first place. </p>
<p>The starting point to understanding Venus is the climate. The average surface temperature is 460°C – far too hot for liquid water and above the <a href="http://www.bbc.co.uk/earth/story/20160209-this-is-how-to-survive-if-you-spend-your-life-in-boilin-water">known thermal limit</a> for life, which is roughly 122°C. </p>
<p>This extreme heat is not simply because Venus is closer to the Sun, but also because it is enveloped by an über-greenhouse atmosphere. At 92 times the pressure of that on Earth, it’s enough to crush modern submarines. If you were standing on the Venusian surface it would be like swimming 1,000 metres below sea level – if the oceans were 460°C, that is. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/171350/original/file-20170529-25203-te8f7z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/171350/original/file-20170529-25203-te8f7z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/171350/original/file-20170529-25203-te8f7z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/171350/original/file-20170529-25203-te8f7z.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/171350/original/file-20170529-25203-te8f7z.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/171350/original/file-20170529-25203-te8f7z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/171350/original/file-20170529-25203-te8f7z.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/171350/original/file-20170529-25203-te8f7z.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">It ain’t half hot, mum.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/smile-crazy-scuba-diver-underwater-selfie-517820569?src=_2NAPKyoHbIWerQe60NRbw-1-85">Andrea Izzotti</a></span>
</figcaption>
</figure>
<p>The scorching temperature of Venus’s surface has many knock-on effects. It means, for example, that there’s no Earth-like plate tectonics. Most of the crust is too soft to snap, and it “<a href="https://www.nature.com/nature/journal/v508/n7497/full/nature13072.html">heals</a>” when broken. There have recently been suggestions that the planet might either have its <a href="http://www.nature.com/ngeo/journal/v10/n5/full/ngeo2928.html">own alternative version</a> of plate tectonics, <a href="http://www.sciencedirect.com/science/article/pii/S0032063315000409">or that</a> the high surface temperature results in the Venusian crust being physically decoupled from mantle flow beneath. At any rate, where plate tectonics <a href="http://www.sciencedirect.com/science/article/pii/B9780123964533000010">is behind</a> 90% of volcanic eruptions on Earth, this is not the case on Venus. </p>
<p>Venus does have volcanoes, but they’re all of the variety we call <a href="https://www.britannica.com/science/intraplate-volcanism">intra-plate or hotspots</a>, where plumes of magma rise up from the mantle and push their way to the surface via cracks in the crust. To study them, we compared them to the ones on Earth. We only considered volcanoes situated on Earth’s oceanic crust, since it is more comparable to the Venusian crust. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/171355/original/file-20170529-25203-i4zq4o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/171355/original/file-20170529-25203-i4zq4o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/171355/original/file-20170529-25203-i4zq4o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=410&fit=crop&dpr=1 600w, https://images.theconversation.com/files/171355/original/file-20170529-25203-i4zq4o.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=410&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/171355/original/file-20170529-25203-i4zq4o.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=410&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/171355/original/file-20170529-25203-i4zq4o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=516&fit=crop&dpr=1 754w, https://images.theconversation.com/files/171355/original/file-20170529-25203-i4zq4o.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=516&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/171355/original/file-20170529-25203-i4zq4o.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=516&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Kilauea in Hawaii, one of Earth’s hotspot volcanoes.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Kīlauea#/media/File:Puu_Oo_cropped.jpg">Wikimedia</a></span>
</figcaption>
</figure>
<p>The oceanic crust covers 60% of Earth’s surface. It is host to more than 100,000 hotspot volcanoes that have formed in less than 100m years. Conversely, Venus’ entire surface has produced only 70,000 individual volcanoes over a period of some 700m years (give or take 300m) – roughly the age of its outer crust. In other words, the difference in the rate of intra-plate volcano production is roughly ten times. (And bear in mind this is a comparison against only a small minority of the total number of volcanoes on Earth since it was formed.) </p>
<h2>Time travelling with argon</h2>
<p>To investigate whether Venus was always so volcanically challenged over its approximately 4.6 billion-year history, we called on the services of argon (Ar). This noble gas comes in three “flavours”, each with a slightly different mass (36, 38 and 40). We know that when Venus and Earth formed, 99% of their argon-36 and argon-38 quickly ended up in the air. </p>
<p>On the other hand, the argon-40 was only able to emerge slowly from the decay of an isotope of potassium that is stored in rocks. To find its way into the air, it then needed a mechanism to transport it there – the most efficient being volcanism. Because Earth’s atmosphere nowadays contains significantly more argon-40 than Venus’s, we can therefore assume Venus has been less volcanically active for its entire existence. </p>
<p>This conclusion probably sounds counter-intuitive – you might expect a hotter planet to be more volcanically active, not less so. When we studied this using rock deformation data, we found a similar phenomenon to the one that prevents plate tectonics on Venus. Because the crust is more like Play-Doh than the toffee brittle of Earth’s crust, it is difficult for magma to move through cracks and form volcanoes. On Venus, we predict, that most magma gets stuck in the Play-Doh – as you can see from the diagram below. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/171347/original/file-20170529-25236-1yqojwt.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/171347/original/file-20170529-25236-1yqojwt.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/171347/original/file-20170529-25236-1yqojwt.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=282&fit=crop&dpr=1 600w, https://images.theconversation.com/files/171347/original/file-20170529-25236-1yqojwt.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=282&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/171347/original/file-20170529-25236-1yqojwt.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=282&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/171347/original/file-20170529-25236-1yqojwt.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=355&fit=crop&dpr=1 754w, https://images.theconversation.com/files/171347/original/file-20170529-25236-1yqojwt.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=355&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/171347/original/file-20170529-25236-1yqojwt.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=355&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption"></span>
</figcaption>
</figure>
<p>Incidentally, this lack of argon-40 in Venus’ atmosphere also probably explains why the planet has never had oceans. This is because the decaying potassium-40 that produces argon-40 exists within silicate minerals. Importantly, the crystal structure of silicate minerals also contains hydroxide anions, which is essentially water. </p>
<p>Indeed, the silicate mantles of both planets <a href="https://deepcarbon.net/feature/water-earth%E2%80%99s-transition-zone-directly-measured#.WSxiwTOZPeQ">can store</a> more than six times the mass of water present in Earth’s oceans. In other words, Earth’s volcanoes not only pumped out life-giving air, but also our oceans. </p>
<p>Furthermore, the great difference in the number of volcanoes may explain the runaway greenhouse effect on Venus. This is because fresh basalt exposed by volcanic eruptions can react with liquid water through a series of chemical reactions known as <a href="http://science.sciencemag.org/content/344/6182/373">carbonation</a> to remove carbon dioxide from the atmosphere. It is an excess of carbon dioxide that is responsible for the greenhouse effect. In short, it is no exaggeration to suggest that volcanoes may explain most of the fundamental differences between Earth and Venus. </p>
<p>For those of us at the <a href="https://www.st-andrews.ac.uk/exoplanets/index.html">St Andrews Centre for Exoplanet Science</a>, we’ll now return to the big picture. We aim to shed more light on how planets become habitable, and how to spot an Earth from a Venus at a distance so great it’s measured in light years. It’s certainly difficult doing this from Earth, but with a great set of PhD students, postdoctoral fellows and an open mind, I am confident we will get to the bottom of it.</p><img src="https://counter.theconversation.com/content/78363/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Sami Mikhail receives funding from the Natural Environment Research Council (NE/P012167/1).</span></em></p>The planet is more similar to Earth than any other – except when it comes to supporting life.Sami Mikhail, Lecturer in Earth Sciences and Environmental Sciences & the Center for Exoplanet Science, University of St AndrewsLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/736482017-04-04T15:04:41Z2017-04-04T15:04:41ZWe are heading for the warmest climate in half a billion years, says new study<figure><img src="https://images.theconversation.com/files/163722/original/image-20170403-21969-1cyjtuf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption"></span> <span class="attribution"><span class="source">Neo Studio / shutterstock</span></span></figcaption></figure><p>Carbon dioxide concentrations are heading towards values not seen in the past 200m years. The sun has also been gradually getting stronger over time. Put together, these facts mean the climate may be heading towards warmth not seen in the past half a billion years.</p>
<p>A lot has happened on Earth since 500,000,000BC – continents, oceans and mountain ranges have come and gone, and complex life has evolved and moved from the oceans onto the land and into the air. Most of these changes occur on very long timescales of millions of years or more. However, over the past 150 years global temperatures have increased by about 1°C, ice caps and glaciers have retreated, polar sea-ice has melted, and sea levels have risen. </p>
<p>Some will point out that Earth’s climate has <a href="https://skepticalscience.com/humans_survived_previous_changes.html">undergone similar changes before</a>. So what’s the big deal?</p>
<p>Scientists can seek to understand past climates by looking at the evidence locked away in rocks, sediments and fossils. What this tells us is that yes, the climate has changed in the past, but the current speed of change is <a href="http://journals.sagepub.com/doi/full/10.1177/2053019616688022">highly unusual</a>. For instance, carbon dioxide hasn’t been added to the atmosphere as rapidly as today for at least the past <a href="http://www.nature.com/ngeo/journal/v9/n4/abs/ngeo2681.html">66m years</a>. </p>
<p>In fact, if we continue on our current path and exploit all convention fossil fuels, then as well as the rate of CO₂ emissions, the absolute climate warming is also likely to be unprecedented in at least the past 420m years. That’s according to a new study we have published in <a href="http://nature.com/articles/doi:10.1038/ncomms14845">Nature Communications</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/163834/original/image-20170404-5725-qfbx8d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/163834/original/image-20170404-5725-qfbx8d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/163834/original/image-20170404-5725-qfbx8d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=348&fit=crop&dpr=1 600w, https://images.theconversation.com/files/163834/original/image-20170404-5725-qfbx8d.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=348&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/163834/original/image-20170404-5725-qfbx8d.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=348&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/163834/original/image-20170404-5725-qfbx8d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=437&fit=crop&dpr=1 754w, https://images.theconversation.com/files/163834/original/image-20170404-5725-qfbx8d.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=437&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/163834/original/image-20170404-5725-qfbx8d.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=437&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Life in the planet’s last greenhouse period, the Eocene.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Eocene_Jay_Matternes.jpg">Jay Matternes / Smithsonian Museum</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>In terms of geological time, 1°C of global warming isn’t particularly unusual. For much of its history the planet was significantly warmer than today, and in fact more often than not Earth was in what is termed a “greenhouse” climate state. During the last greenhouse state 50m years ago, global average temperatures were 10-15°C warmer than today, the polar regions were ice-free, <a href="https://theconversation.com/how-ancient-warm-periods-can-help-predict-future-climate-change-58036">palm trees grew on the coast of Antarctica</a>, and alligators and turtles wallowed in swamp-forests in what is now the frozen Canadian Arctic. </p>
<p>In contrast, despite our current warming, we are still technically in an “icehouse” climate state, which simply means there is ice on both poles. The Earth has naturally cycled between these two climate states every 300m years or so.</p>
<p>Just prior to the industrial revolution, for every million molecules in the atmosphere, about 280 of them were CO₂ molecules (280 parts-per-million, or ppm). Today, due primarily to the burning of fossil fuels, concentrations are about 400 ppm. In the absence of any efforts to curtail our emissions, burning of conventional fossil fuels will cause CO₂ concentrations to be around 2,000ppm by the year 2250. </p>
<p>This is of course a lot of CO₂, but the geological record tells us that the Earth has experienced similar concentrations several times in the past. For instance, our new compilation of data shows that during the Triassic, around 200m years ago, when dinosaurs first evolved, Earth had a greenhouse climate state with atmospheric CO₂ around 2,000-3,000ppm. </p>
<p>So high concentrations of carbon dioxide don’t necessarily make the world totally uninhabitable. The dinosaurs thrived, after all. </p>
<p>That doesn’t mean this is no big deal, however. For a start, there is no doubt that humanity will face major socio-economic challenges dealing with the <a href="http://advances.sciencemag.org/content/1/8/e1500589">dramatic and rapid climate change</a> that will result from the rapid rise to 2,000 or more ppm. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/163723/original/image-20170403-21963-1j6wrmn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/163723/original/image-20170403-21963-1j6wrmn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/163723/original/image-20170403-21963-1j6wrmn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/163723/original/image-20170403-21963-1j6wrmn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/163723/original/image-20170403-21963-1j6wrmn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/163723/original/image-20170403-21963-1j6wrmn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/163723/original/image-20170403-21963-1j6wrmn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/163723/original/image-20170403-21963-1j6wrmn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">If we burnt all fossil fuel reserves the vast Antarctic ice sheet may disappear.</span>
<span class="attribution"><span class="source">vladsilver / shutterstock</span></span>
</figcaption>
</figure>
<p>But our new study also shows that the same carbon concentrations will cause more warming in future than in previous periods of high carbon dioxide. This is because the Earth’s temperature does not just depend on the level of CO₂ (or other greenhouse gases) in the atmosphere. All our energy ultimately comes from the sun, and due to the way the sun generates energy through nuclear fusion of hydrogen into helium, its brightness has increased over time. Four and a half billion years ago when the Earth was young the sun was around 30% less bright.</p>
<p>So what really matters is the combined effect of the sun’s changing strength and the varying greenhouse effect. Looking through geological history we generally found that as the sun became stronger through time, atmospheric CO₂ gradually decreased, so both changes cancelled each other out on average. </p>
<p>But what about in the future? We found no past time period when the drivers of climate, or <a href="http://ossfoundation.us/projects/environment/global-warming/radiative-climate-forcing">climate forcing</a>, was as high as it will be in the future if we burn all the readily available fossil fuel. Nothing like it has been recorded in the rock record for at least 420m years. </p>
<p>A central pillar of geological science is the <a href="http://www.uniformitarianism.net/">uniformitarian principle</a>: that “the present is the key to the past”. If we carry on burning fossil fuels as we are at present, by 2250 this old adage is sadly no longer likely to be true. It is doubtful that this high-CO₂ future will have a counterpart, even in the vastness of the geological record.</p><img src="https://counter.theconversation.com/content/73648/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Gavin Foster receives funding from the Natural Environment Research Council (NERC). </span></em></p><p class="fine-print"><em><span>Dan Lunt receives funding from the Natural Environment Research Council (NERC).</span></em></p><p class="fine-print"><em><span>Dana Royer does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>The sun is more powerful today than when we last had similar levels of carbon in the atmosphere.Gavin Foster, Professor of Isotope Geochemistry, University of SouthamptonDana Royer, Professor of Earth and Environmental Sciences, Wesleyan UniversityDan Lunt, Professor of Climate Science, University of BristolLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/438172015-06-29T09:48:23Z2015-06-29T09:48:23ZOur mostly dry planetary neighbors once had lots of water—what does that imply for us?<figure><img src="https://images.theconversation.com/files/86587/original/image-20150626-1431-1oz4qeu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Once there was water....</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/cedwardbrice/14120236648">CEBImagery</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span></figcaption></figure><p>We already knew about Venus. We had our suspicions about Mars. Now we’re sure.</p>
<p>Our two closest solar system neighbors once had oceans – planet-encircling, globe-girdling, Earth-like oceans. But waterbearing planets are fragile. Venus didn’t have the right stuff and lost her oceans to space. We have the smoking gun. And now we know that Mars, also, poor Mars, couldn’t hold on. Mars has lost to space at least 80% of all the water it once had.</p>
<p><em>Et tu</em>, Earth? What about you? More to the point, what about us? Despite water’s apparent abundance, what does the future hold for the most precious material on our planet? Will we find a way to mistreat our reserve of irreplaceable water and turn our planet into a planetary desert, like our neighbors Venus and Mars? Kick the temperature up a few more notches, thanks to a runaway <a href="http://www.epa.gov/climatestudents/basics/today/greenhouse-effect.html">greenhouse effect</a>, and the ultimate consequence of global warming could be ejecting the water from our planet. </p>
<h2>Water on the atomic level</h2>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/86589/original/image-20150626-1438-1pl1bc5.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/86589/original/image-20150626-1438-1pl1bc5.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/86589/original/image-20150626-1438-1pl1bc5.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=432&fit=crop&dpr=1 600w, https://images.theconversation.com/files/86589/original/image-20150626-1438-1pl1bc5.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=432&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/86589/original/image-20150626-1438-1pl1bc5.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=432&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/86589/original/image-20150626-1438-1pl1bc5.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=543&fit=crop&dpr=1 754w, https://images.theconversation.com/files/86589/original/image-20150626-1438-1pl1bc5.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=543&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/86589/original/image-20150626-1438-1pl1bc5.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=543&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Two H’s and an O make a water molecule.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Water_molecule_2.svg">Sakurambo</a></span>
</figcaption>
</figure>
<p>Let’s try our hand at interplanetary forensics. First, let me introduce you to the atomic constituents of that substance chemists call H2O, which most of us more commonly know as water. The H represents the atom hydrogen. The O represents the atom oxygen. The number two after the letter H tells us that a single molecule of water is composed of two hydrogen atoms and one oxygen atom.</p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/86590/original/image-20150626-1438-1tj93sz.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/86590/original/image-20150626-1438-1tj93sz.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/86590/original/image-20150626-1438-1tj93sz.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/86590/original/image-20150626-1438-1tj93sz.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/86590/original/image-20150626-1438-1tj93sz.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/86590/original/image-20150626-1438-1tj93sz.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/86590/original/image-20150626-1438-1tj93sz.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/86590/original/image-20150626-1438-1tj93sz.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"></a>
<figcaption>
<span class="caption">Deuterium is hydrogen but with an extra uncharged neutron.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Blausen_0527_Hydrogen-2_Deuterium.png">BruceBlaus</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>In order to enter the world of CSI: Solar System, we need to understand the structure of atoms in a bit more detail. Hydrogen is hydrogen because its nucleus has one positively charged proton, which is orbited by one negatively charged electron. The nucleus, however, can also include one neutron, which lacks a charge. Even with one neutron, the atom still has a positive charge in the nucleus of +1. It’s therefore still hydrogen, but with one critical difference: it is much heavier, about twice as heavy, in fact, thanks to the additional neutron.</p>
<p>Chemists call this kind of heavy hydrogen deuterium. Deuterium behaves identically in chemical reactions to regular hydrogen; it’s just heavier. Remember that H2O molecule? When made with a deuterium atom, it’s an HDO molecule. It would taste the same, and it would provide the same sustenance to your flowers and gerbils, but it would weigh more.</p>
<p>That extra weight makes all the difference, because Isaac Newton’s and Albert Einstein’s unavoidable law of gravity says that deuterium is pulled downward toward the surface of a planet much more strongly than is regular hydrogen. When deuterium and regular hydrogen are both free to bounce around in a planet’s atmosphere, the regular hydrogen will bounce much higher. And if the planet’s gravity is weak enough – which is the case for Earth, Venus and Mars – regular hydrogen can bounce so high that it can escape into space, whereas the deuterium remains forever bound by gravity to the planet.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/86591/original/image-20150626-1438-igrybt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/86591/original/image-20150626-1438-igrybt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/86591/original/image-20150626-1438-igrybt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=473&fit=crop&dpr=1 600w, https://images.theconversation.com/files/86591/original/image-20150626-1438-igrybt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=473&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/86591/original/image-20150626-1438-igrybt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=473&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/86591/original/image-20150626-1438-igrybt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=594&fit=crop&dpr=1 754w, https://images.theconversation.com/files/86591/original/image-20150626-1438-igrybt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=594&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/86591/original/image-20150626-1438-igrybt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=594&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Galileo’s probe lasted less than an hour before being destroyed by Jupiter’s atmosphere.</span>
<span class="attribution"><a class="source" href="http://solarsystem.nasa.gov/multimedia/display.cfm?IM_ID=1585">NASA</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>A base-level ratio for the solar system</h2>
<p>In 1995, NASA’s <a href="http://solarsystem.nasa.gov/galileo/">Galileo</a> probe measured the ratio of hydrogen to deuterium in the atmosphere of the giant planet Jupiter and found that <a href="http://dx.doi.org/10.1023/A:1005091806594">ratio to be about 40,000-to-1</a>.</p>
<p>Jupiter is such a massive planet that neither hydrogen nor deuterium can escape. Consequently, planetary scientists are quite certain that all the materials involved in the mixture of gases and dust that formed the sun and all the planets in our solar system formed with the same ratio of hydrogen to deuterium as the Galileo probe found for Jupiter’s atmosphere. We take it as a given that all the water originally deposited on Venus, on Earth, and on Mars also had that same ratio of hydrogen to deuterium.</p>
<p>Now let’s do some chemistry. If I wanted to make 20,000 water molecules, I would need a total of 40,000 hydrogen (H) and deuterium (D) atoms (of which 39,999 would be H and 1 would be D), plus, of course, 20,000 oxygen (O) atoms. In my mixture of 20,000 water molecules, I would be able to make 19,999 H2O molecules and one HDO molecule, given my initial ratio of hydrogen to deuterium atoms.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/86592/original/image-20150626-1402-i8ipay.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/86592/original/image-20150626-1402-i8ipay.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/86592/original/image-20150626-1402-i8ipay.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=326&fit=crop&dpr=1 600w, https://images.theconversation.com/files/86592/original/image-20150626-1402-i8ipay.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=326&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/86592/original/image-20150626-1402-i8ipay.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=326&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/86592/original/image-20150626-1402-i8ipay.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=409&fit=crop&dpr=1 754w, https://images.theconversation.com/files/86592/original/image-20150626-1402-i8ipay.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=409&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/86592/original/image-20150626-1402-i8ipay.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=409&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Still more H than D, but less than you might think….</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/jeyh/2635397121">Jeyheich</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<h2>The real H-to-D ratios</h2>
<p>In a cup of water scooped from any part of any of Earth’s oceans, in any local freshwater pond from any continent, in any cup of tea in any city, in an Alpine glacier or a hot spring in Yellowstone, the hydrogen-to-deuterium ratio is 6,250-to-1, not 40,000-to-1.</p>
<p>Why so low? The evidence suggests that early in Earth’s history, our planet lost a great deal of hydrogen (but not deuterium). As the hydrogen atoms escaped to space, the H-to-D ratio would have dropped from 40,000-to-1 to only 6,250-to-1. In fact, the Earth may have lost as much as 80% of its original population of hydrogen atoms, and since, on Earth, most hydrogen atoms are bound into water molecules, the loss of hydrogen atoms is likely equivalent to the loss of water.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/86593/original/image-20150626-1433-1wphjjl.gif?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/86593/original/image-20150626-1433-1wphjjl.gif?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/86593/original/image-20150626-1433-1wphjjl.gif?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=789&fit=crop&dpr=1 600w, https://images.theconversation.com/files/86593/original/image-20150626-1433-1wphjjl.gif?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=789&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/86593/original/image-20150626-1433-1wphjjl.gif?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=789&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/86593/original/image-20150626-1433-1wphjjl.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=992&fit=crop&dpr=1 754w, https://images.theconversation.com/files/86593/original/image-20150626-1433-1wphjjl.gif?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=992&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/86593/original/image-20150626-1433-1wphjjl.gif?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=992&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 atmospheric probe descends through the Venusian cloud deck.</span>
<span class="attribution"><a class="source" href="http://heasarc.gsfc.nasa.gov/docs/heasarc/missions/images/pvo_images.html">Ames Research Center and Hughes Aircraft Company</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>NASA’s <a href="http://www.nasa.gov/mission_pages/pioneer-venus/">Pioneer Venus</a> spacecraft, way back in 1978, dropped a probe that parachuted into and measured the properties of Venus’ atmosphere. One of its shocking discoveries was that the <a href="http://dx.doi.org/10.1126/science.216.4546.630">hydrogen-to-deuterium ratio on Venus is only 62-to-1</a>, fully 100 times smaller than the ratio on Earth.</p>
<p>The clear implication of this discovery is that Venus was once wet but is now bone-dry. Venus, as we now know, has a surface temperature of 867 Fahrenheit (463 Celsius). Venus once had oceans, but Venus warmed up and the oceans boiled off the surface. Then ultraviolet light from the sun split the water molecules apart into their constituent atoms. As a result, the lighter hydrogen atoms bubbled up to the top of the atmosphere and escaped into space, while the heavier deuterium atoms were trapped by Venus’ gravitational pull. The hydrogen-to-deuterium ratio in Venus’ atmosphere is the crucial clue that provides the evidence for what happened a billion or more years ago on Venus.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/86595/original/image-20150626-1398-cljyh6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/86595/original/image-20150626-1398-cljyh6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/86595/original/image-20150626-1398-cljyh6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=268&fit=crop&dpr=1 600w, https://images.theconversation.com/files/86595/original/image-20150626-1398-cljyh6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=268&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/86595/original/image-20150626-1398-cljyh6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=268&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/86595/original/image-20150626-1398-cljyh6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=336&fit=crop&dpr=1 754w, https://images.theconversation.com/files/86595/original/image-20150626-1398-cljyh6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=336&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/86595/original/image-20150626-1398-cljyh6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=336&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Mars looks pretty dry now, but mineral veins were deposited by fluids moving through rock.</span>
<span class="attribution"><a class="source" href="http://www.nasa.gov/content/curiosity-sees-prominent-mineral-veins-on-mount-sharp-mars">NASA</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Now, in research just published in Science this spring, a team of scientists led by G L Villanueva of NASA Goddard Space Flight Center has used <a href="http://dx.doi.org/10.1126/science.aaa3630">powerful telescopes on Earth to map</a> water (H2O) and its deuterated form (HDO) across the surface of Mars. They’ve confirmed the results obtained by NASA’s <a href="http://www.nasa.gov/mission_pages/msl/index.html">Curiosity/Mars Science Laboratory</a> in 2013 that the hydrogen-to-deuterium ratio on Mars is <a href="http://dx.doi.org/10.1126/science.1237961">smaller by a factor of about 7</a> compared to that on Earth. This measurement tells us that Mars, like Venus, has lost lots of hydrogen, which means Mars, like Venus, has lost lots of its water. </p>
<p>The total amount of water identified in all currently existing water reservoirs on Mars (the ice caps – which have some water but are mostly frozen carbon dioxide; atmospheric water; ice-rich regolith layer; near-surface deposits) would generate a global ocean about 21 meters (68 feet) deep. The deuterium measurements tell us that Mars once had about seven times more water, enough water to create an ocean that would have covered the entire planet to a depth of at least 137 meters (445 feet). The evidence is now clear: Mars has lost at least 85% of the water it once had. (And that estimate assumes the Earth has not lost any of its water; if the Earth also has lost 80% of its original water reservoir, then Mars has lost 97% of its original water reservoir.)</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/86596/original/image-20150626-1402-f9d6f1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/86596/original/image-20150626-1402-f9d6f1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/86596/original/image-20150626-1402-f9d6f1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=558&fit=crop&dpr=1 600w, https://images.theconversation.com/files/86596/original/image-20150626-1402-f9d6f1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=558&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/86596/original/image-20150626-1402-f9d6f1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=558&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/86596/original/image-20150626-1402-f9d6f1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=702&fit=crop&dpr=1 754w, https://images.theconversation.com/files/86596/original/image-20150626-1402-f9d6f1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=702&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/86596/original/image-20150626-1402-f9d6f1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=702&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Is Venus’ present Earth’s future?</span>
<span class="attribution"><a class="source" href="http://apod.nasa.gov/apod/ap050903.html">Magellan Project, JPL, NASA</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Whither goest Venus and Mars….</h2>
<p>Venus and Mars. Mars and Venus. Planetary scientists know that both planets were wet and Earth-like in the beginning; they also know that neither Venus nor Mars could hold onto their water for long enough to nurture advanced life forms until they could flourish. The lessons from Venus and Mars are clear and simple: water worlds are delicate and fragile. Water worlds that can survive the ravages of aging, whether natural or inflicted by their inhabitants – and can nurture and sustain life over the long term – are rare and precious.</p>
<p>If we allow the temperature of our planet to rise a degree or two, we may survive it as a minor environmental catastrophe. But beyond a few degrees, do we know the point at which global warming sends our atmosphere into a runaway death spiral, turning Earth into Venus? We know what the endgame looks like.</p><img src="https://counter.theconversation.com/content/43817/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>David Weintraub 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>Some atomic ratio detective work on our solar system neighbors tells us a lot about their watery pasts. That Venus and Mars are mostly dry now could be a cautionary tale for us on the Blue Planet.David Weintraub, Professor of Astronomy, Vanderbilt UniversityLicensed as Creative Commons – attribution, no derivatives.