A “blocking” weather system lingering high above the UK has produced one of the driest, warmest and brightest starts to spring on record.
April 2025 was the sunniest since records began in 1910. This followed the third-sunniest March, and both months saw temperatures well above average nationwide. On May 1, the temperature reached 29.3°C in Kew Gardens in London – a new record for the date.
Meteorologists are warning of the potential for a summer drought, as the UK has seen roughly half its usual amount of rainfall for March and April. While farmers fret about this year’s harvest, some water companies are urging customers to help reservoir levels recover by limiting water use.
Meanwhile, wildfires have engulfed forest and moorland in areas of Scotland, Wales and England.
Most of the UK has experienced a record-dry spring so far. Met Office
For several weeks, a stubborn area of high pressure over the UK has diverted the usual flow of mild, moist air from the North Atlantic like a boulder in a river. This is known as a blocking weather system.
Within it, air descends, warms and dries, which is why this weather pattern tends to be linked to heatwaves and drought. Blocking is usually persistent, making it seem like the weather is stuck.
Here’s how climate change may have played a role in setting up this unusual spring.
The warming climate means that unusually warm weather is occurring more often and becoming more intense. At the same time, we can expect more periods of both severe drought and extreme rainfall. Sudden changes from drought to deluge, termed “weather whiplash”, are due to the intensification of the water cycle in a warmer atmosphere that can hold more water vapour.
However, certain weather patterns are necessary to produce extreme weather. More blocking events in future could increase the chance of heatwaves or drought. But are blocking weather patterns becoming more common?
It’s difficult to determine how weather patterns will change as a result of the rising concentration of greenhouse gases in the atmosphere, which is predominantly caused by the burning of fossil fuels.
Part of the difficulty arises from the fact that weather patterns vary year to year. Several years in a row with more blocking events than usual could make it seem like blocking is increasing due to climate change, but it could simply be down to chance.
As a result, it is difficult to detect the fingerprint of human activity from weather observations alone. For example, blocking weather patterns over Greenland during summer have happened more often in recent decades, which can enhance the melting of the ice sheet. But it isn’t clear that this trend is the result of human-induced climate change.
Climate models do suggest future changes in the occurrence of blocking, however. These computer simulations, consisting of equations that describe the fundamental physics of the atmosphere, are the main tool scientists use to perform experiments that parse how the climate will behave in future.
When scientists run climate model simulations with increased greenhouse gas concentrations the results consistently show a decrease in blocking events. But blocking generally happens more often in real life than model simulations, which reduces the confidence scientists have in future projections.
Keeping track of the jet stream
The movement of weather systems in Earth’s mid-latitudes – including over the UK – is linked to the jet stream, which is a fast-flowing river of air driven by the contrast in temperature between the poles and mid-latitudes.
Some researchers have suggested that, because the Arctic is warming faster than the tropics, the jet stream may weaken and become more “wavy”, increasing the occurrence of blocking events, contrary to what most climate models show.
Outside of the scientific community, this idea has become popular. However, the hypothesis remains controversial among scientists, and observational evidence has weakened in recent years.
In fact, around ten kilometres above the Earth’s surface, near commercial aircraft cruising altitudes, the opposite trends are occurring: the temperature difference between the Arctic and mid-latitudes is increasing, acting to increase the strength of the jet stream.
There are considerable challenges with understanding how climate change is affecting the large-scale atmospheric patterns which drive the weather we experience. These include large natural variability and imperfect climate models. Models mostly suggest a decline in blocking events with climate change, though this remains relatively uncertain compared with other aspects of the science.
Overall, we can be confident that climate change is bringing warmer conditions in all seasons. Scientists also have strong evidence to suggest that drought conditions will become more common. These changes are already affecting food production, energy generation and water availability and these impacts will continue to worsen with climate change.
Members of the “Red Rebel Brigade” led a procession around Cambridge, England as part of a funeral for the Paris agreement’s 1.5°C temperature target on May 10, 2025. (Photo: Derek Langley)
“We felt we needed a physical space where we could grieve together for what we are losing, and reflect on how to respond to the challenge now in front of us,” said Alex Martin of Extinction Rebellion Cambridge.
Extinction Rebellion and other climate organizations on Saturday held a funeral for the Paris agreement’s 1.5ºC temperature target in Cambridge, England.
“The mock funeral idea grew out of the need to process the enormity and sadness of this moment,” Alex Martin of Extinction Rebellion (XR) Cambridge said in a statement. “While many people are distracted by 1,001 things on their phones, we felt we needed a physical space where we could grieve together for what we are losing, and reflect on how to respond to the challenge now in front of us.”
Almost a decade ago, parties to the Paris treaty agreed to work toward limiting temperature rise this century to 1.5ºC—but 2024 was the hottest year in human history, and countries around the world show no signs of reining in planet-wrecking fossil fuels anywhere near the degree that scientists warn is necessary to prevent catastrophic climate breakdown.
“Crossing 1.5ºC for a whole calendar year is a wake-up call for the world,” said Olympic gold medalist and XR U.K. spokesperson Etienne Stott, highlighting another alarming record from last year. “If we want to avoid crossing further tipping points we need a complete transformation of society.”
Extinction Rebellion and other climate groups held a funeral for the Paris agreement’s 1.5°C temperature target in Cambridge, England on May 10, 2025. (Photo: Derek Langley)
Scientists from universities in the United Kingdom and Germany warned in a peer-reviewed paper published in the journal Earth System Dynamics last month that humankind is at risk of triggering various climate tipping points absent urgent action to dramatically reduce emissions from fossil fuels.
“There are levers policymakers can pull to rapidly phase out fossil fuels, but this requires standing up to powerful interests,” Stott said Saturday. “Activists need to build power, resilience, and the world we want to see in our communities; but we also need to keep seeking the spark that will cause the worldwide transformation we need to see.”
In addition to the Cambridge and U.K. arms of Extinction Rebellion, Saturday’s action was organized by Cambridge Greenpeace, Cambridge Stop the War, and the Organization of Radical Cambridge Activists (ORCA).
Varsity, the independent student newspaper at the University of Cambridge, reported that the marchers “rallied at Christ’s Pieces, where they heard from one of the organizers, who emphasised the harm caused by exceeding 1.5ºC of warming.”
“The march then proceeded up Christ’s Lane and down Sidney Street, led by a group of ‘Red Rebels,’ dressed in red robes with faces painted white, followed by ‘pall bearers’ carrying coffins painted black, with the words ‘Inaction Is Death’ in white,” according to Varsity. “The procession was completed by a samba band who drummed as they walked, followed by protesters carrying a large sign reading ‘Don’t silence the science,’ along with many other smaller placards.”
Members of the “Red Rebel Brigade” led a procession around Cambridge, England as part of a funeral for the Paris agreement’s 1.5°C temperature target on May 10, 2025. (Photo: Derek Langley)
Photos from organizers show participants displaying banners with messages such as “No Future on a Dead Planet,” and additional messages painted on the black coffins: “1.5ºC Is Dead,” “Act Now,” “Ecocide,” “RIP Earth,” and “Web of Life.”
“Politicians have broken their promises to keep global temperature rises to a livable 1.5ºC,” declared Zoe Flint, a spokesperson for XR Cambridge. “For decades, people around the world have been resisting environmental devastation in their own communities and beyond—often facing state repression and violence as a result.”
“With dozens of political protesters now in prison in this country, that repression has come to the U.K. too,” Flint noted. “But when those least responsible for climate breakdown suffer the worst effects, we can’t afford to give up the fight.”
Parties to the Paris agreement are set to gather next in November at the United Nations climate summit, COP30, in Belém, Brazil.
Orcas discuss Donald Trump and the killer apes’ concept of democracy. Front Orca warns that Trump is crashing his country’s economy and that everything he does he does for the fantastically wealthy.Elon Musk urges you to be a Fascist like him, says that you can ignore facts and reality then.Climate Science Denier Donald Trump says Burn, Baby, Burn.
Damaged structures and homes are seen after the Palisades fire in the Pacific Palisades neighborhood of Los Angeles on January 11, 2025. (Photo: Axelle/Bauer-Griffin/GC Images)
“Their philosophy is, if we ignore it, it’s not a problem,” said one meteorologist.
On the heels of the news that higher-than-average temperatures continued globally in April, one of the United States’ top science agencies announced Thursday that it will no longer update a database that tracks climate disasters that cause billions of dollars in damage.
As of Thursday, the Billion Dollar Weather and Climate Disasters database on the National Oceanic and Atmospheric Administration’s (NOAA) website was replaced with a message saying there have been no such events in 2025 through April 8.
That flies in the face of an analysis by the National Centers for Environmental Information, which has maintained the database and said before it was taken down that six to eight billion-dollar climate disasters have happened so far this year, including the wildfires that devastated parts of Los Angeles in January and caused an estimated $150 billion in damage.
The World Weather Attribution said in late January that planetary heating, fueled by greenhouse gas emissions, caused weather conditions in Southern California that made the fires 35% more likely.
Hundreds of people have been laid off from NOAA in recent weeks as the so-called Department of Government Efficiency, led by billionaire tech CEO Elon Musk, has pushed to slash government spending, and those who have lost their jobs include scientists who helped maintain the database.
NOAA spokesperson Kim Doster told The Washington Post that in addition to staff changes, “evolving priorities” were also partially behind the retiring of the database, which will now show disasters that occurred only between 1980-2024.
Between 2020-24, the number of billion-dollar disasters averaged 23 per year, compared to just a few per year in the 1980s.
“This Trump administration move is the dumbest magic trick possible: covering their eyes and pretending the problem will go away if they just stop counting the costs. Households across the country already have to count these costs at their kitchen table as they budget for higher insurance costs and home repairs. Families and retirees dipping into their savings or going bankrupt to recover from wildfires and hurricanes know what disasters cost,” said Carly Fabian, senior insurance policy advocate with Public Citizen’s Climate Program. “Hiding the national tallies will only undermine our ability to prepare and respond to the climate crisis. Deleting the data will exacerbate the devastating delays in acting to slow climate change, and the impacts it is having on property insurance and housing costs.”
NOAA’s “evolving priorities” have also included decommissioning other datasets, including one tracking marine environments and one tracking ocean currents.
Without NOAA’s Billion Dollar Weather and Climate Disasters database, Jeremy Porter, co-founder of the climate risk financial modeling firm First Street, told CNN that “replicating or extending damage trend analyses, especially at regional scales or across hazard types, is nearly impossible without significant funding or institutional access to commercial catastrophe models.”
“What makes this resource uniquely valuable is not just its standardized methodology across decades, but the fact that it draws from proprietary and nonpublic data sources (such as reinsurance loss estimates, localized government reports, and private claims databases) that are otherwise inaccessible to most researchers,” he said.
Chris Gloninger, a meteorologist who resigned from an Iowa news station after receiving threats for his frank, science-based coverage of climate disasters, said the retiring of the database suggests the Trump administration is “okay with spending billions of dollars on disasters.”
Billion dollar disasters are a way to track how our weather is turning more extreme because of #climatechange
— Chris Gloninger, CCM, CBM (@ChrisGloninger) May 8, 2025
“Every dollar that we spend on mitigation or adaptation saves $13 in recovery costs,” said Gloninger. “But their philosophy is, if we ignore it, it’s not a problem.”
Elon Musk urges you to be a Fascist like him, says that you can ignore facts and reality then.Neo-Fascist Climate Science Denier Donald Trump says Burn, Baby, Burn.Orcas discuss how Trump was re-elected and him being an insane, xenophobic Fascist.
U.S. President Donald Trump next to the Thames Water and KKR logos. DeSmog collage. Credit: Gage Skidmore / Thames Water / KKR
The U.S. private equity firm KKR, which has been selected as the ‘preferred bidder’ for the takeover of Thames Water, gave a seven-figure sum to Donald Trump’s inauguration committee, DeSmog can report.
Official records show that Kohlberg Kravis Roberts Co LP (KKR) donated $1 million to the Trump Vance Inaugural Committee on 7 January. The committee is appointed by the president-elect to arrange the inauguration ceremony, when a U.S. president is formally sworn into office.
The embattled London-based utilities provider Thames Water, in debt to the tune of £20 billion, is attempting to secure new investment to save it from nationalisation. In March, KKR was granted preferred bidder status, giving it a 10-week period to raise the equity to buy the water company.
KKR is reported to have lodged an initial £4 billion bid in exchange for a majority stake in Thames Water, which serves 16 million customers.
However, campaigners have raised concerns about KKR’s suitability to own Thames Water, given its financial ties to Trump.
“KKR recently donated $1 million to the inauguration fund of President Trump, a man who has repeatedly called the climate crisis a hoax,” said Matthew Topham, lead campaigner at the pro-nationalisation campaign group We Own It. “Let’s not kid ourselves that this company will swoop in and clean up our rivers and lakes.
“The government has ducked the issue for too long – special administration to slash the rotten debt, then full public ownership, is the only way to reverse this catastrophe.”
The new Trump administration has initiated a bonfire of clean air and water regulations – rules that were set to save the lives of 200,000 people according to The Guardian. Gina McCarthy, chair of the Environmental Protection Agency (EPA) under former U.S. President Barack Obama, said the announcement of the mass rollbacks was the “most disastrous day in EPA history”. During his first term, from 2017 to 2021, Trump repealed more than 100 environmental regulations.
Since being inaugurated for a second time, Trump has pledged to once again withdraw the U.S. from the flagship 2015 Paris Agreement, which set an international target for limiting global warming, and has declared a “national energy emergency” to allow the U.S. to “drill, baby, drill” for new fossil fuels.
KKR’s prospective ownership of a vital public utility has also been questioned on the basis of the U.S. firm’s business model. Private equity firms – which buy and restructure companies – are known to cut costs, and increase prices for consumers, in order to maximise their profits.
KKR was infamously dubbed the “Barbarians at the Gate” in the late 1980s for its takeover of U.S. conglomerate RJR Nabisco.
“It beggars belief that anyone could seriously think this is a business model and owner who will truly fix the crisis at Thames Water,” said Mathew Lawrence, director of the think tank Common Wealth. “It is exactly the behaviour of loading Thames Water up with debt, extracting money, and underinvesting that has led us to this point. What is needed is long-term stewardship, patient investment, and putting the public and our water system first for once – not the interests of elite financial firms.”
These sentiments were reflected in Parliament this week, through a House of Lords address by Labour peer Prem Sikka. “Thames Water was put on the road to ruin by private equity,” he said. “Now its shareholders have designated KKR, another private equity group, as their preferred bidder. KKR’s business model is profiteering, high leverage, low investment, asset stripping and high cash extraction. That will inevitably multiply Thames’s problems.”
KKR and Thames Water were approached for comment.
Debt and Donations
Thames Water’s debt ballooned under the ownership of Australian private equity firm Macquarie, increasing from £3.4 billion in 2006 to £10.8 billion when the firm sold its stake in 2017.
During Macquarie’s ownership of Thames Water, the private equity firm extracted roughly £2.7 billion in dividends and a further £2.2 billion in loans. Despite this, Macquarie has recently said that it is “very proud” of its ownership record.
KKR’s preliminary bid proposed a mechanism that would allow the holders of Thames Water debt – including the U.S. hedge fund Elliott Management – to become Thames Water shareholders.
Elliott Management is an activist hedge fund that recently built up a large stake in BP and has urged the British fossil fuel major to ditch a number of its green commitments. BP’s profits recently dropped by 48 percent amid this pivot back to oil and gas. The hedge fund is run by Paul Singer, who also donated $1 million to Trump’s inauguration committee.
Turning around the performance of Thames Water will take considerable investment and business acumen. Thames Water reported a 40 percent increase in pollution incidents in the first half of 2024, while the firm has been allowed to raise customer bills by 35 percent on average over the upcoming years. Senior KKR Europe executive Johannes Huth said last year that water bills must rise to boost investment in ageing infrastructure.
KKR also has a 25 percent stake in Northumbrian Water, which it acquired in 2022.
KKR’s Connections
In addition to its donation to Trump’s inauguration fund, KKR has other ties to fossil fuels and those who oppose climate action.
Analysis by the investigative group Private Equity Climate Risks published in April 2024 reported that KKR has a large fossil fuel portfolio, with 188 assets in 21 countries.
KKR has also created a $50 billion fund with Energy Capital Partners to invest in artificial intelligence (AI) data centre energy infrastructure. Data centres are heavily energy intensive, and DeSmog recently revealed that AI executives have told major polluters that the nascent industry can keep fossil fuels alive.
KKR is also the co-owner of Marshall Wace, a hedge fund co-founded by UK media baron Paul Marshall, holding a 39.9 percent stake as of June 2023. The same month, Marshall Wace reported investments of at least £1.8 billion in fossil fuels companies, including in the oil and gas giants Shell, Chevron, and Equinor.
Marshall is the co-owner of GB News, a broadcaster that has frequently given a platform to climate falsehoods, and is an opponent of policies to reach net zero emissions.
Speaking at a conference in February hosted by the Alliance for Responsible Citizenship (ARC), a group funded by Marshall, he said that the UK’s net zero plans are “leading the way in wrecking our industrial base”, “impoverishing people”, “sacrificing our energy security”, and “sacrificing our ancient rural landscape.”
The UK’s net zero sector is growing at three times the rate of the rest of the economy, according to the Confederation of British Industry (CBI).
DeSmog also revealed that Warren Stephens, Trump’s ambassador to the UK, donated $4 million to the president’s inauguration fund on the day that he was nominated for the diplomatic position.
The inauguration committee raised a record $239 million, including from fossil fuel giants Chevron ($2 million), ExxonMobil ($1 million), the U.S. branches of BP and Shell ($500,000 each), and Valero ($250,000).
The “wealthiest 10%” of people on the planet are “responsible” for 65% of the 0.61C increase in global average temperatures over 1990-2020, according to new research.
The study, published in Nature Climate Change, uses a field of climate science called “attribution” to determine the contribution of the world’s “wealthiest population groups” to climate change through the greenhouse gases they emit.
The authors also calculate the contribution of these high-income groups to the increasing frequency of heatwaves and droughts.
For example, the study finds the wealthiest 10% of people – defined as those who earn at least €42,980 (£36,605) per year – contributed seven times more to the rise in monthly heat extremes around the world than the global average.
In another finding, the Amazon rainforest faced a threefold increase in the likelihood of droughts over the period studied, most of which was driven by the wealthiest 10% of the world’s population.
The authors also explore country-level emissions, finding that the wealthiest 10% in the US produced the emissions that caused a doubling in heat extremes across “vulnerable regions” globally.
One scientist not involved in the study tells Carbon Brief that efforts to attribute global warming to individual income groups is an “important step towards targeted policies” and could support climate litigation.
Emissions inequality
Humans emit more than 40bn tonnes of CO2 into the atmosphere every year. Developed countries are responsible for the majority of global emissions, as a result of the typically more carbon-intensive lifestyles of their residents.
Meanwhile, the most severe impacts of climate change are disproportionately felt by the poorest and most vulnerable people.
The new study uses an income and wealth inequality dataset from the World Inequality Database to track inequality over 1990-2019, showing how much the world’s wealthiest 10%, 1% and 0.1% of society have contributed to warming over 1990-2020. (For details on the method, see the modelling inequalities section below.)
The world’s wealthiest 10% all earn more than €42,980 (£36,605) per year, according to the database. Meanwhile, the world’s wealthiest 0.1% earn more than €537,770 (£458,011) per year.
Of the 0.61C increase in global average temperatures over 1990-2020, the authors estimate that 65% was due to the emissions of the wealthiest 10% of people on the planet. For the wealthiest 0.1%, the estimate is 8%.
The graph below shows how much global temperatures would have risen over 1990-2020 if everyone in the world emitted as much as the world’s poorest 50% (purple), middle 40% (green), richest 10% (orange), richest 1% (blue) and richest 0.1% (pink) people. The grey bar shows how much global temperatures actually rose.
How global temperatures would have risen if everyone in the world emitted the world produced the same amount of emissions, on average, as individuals in the bottom 50% (purple), middle 40% (green), top 10% (orange), top 1% (blue) and top 0.1% (pink) of the world’s emitters. Source: Schöngart et al (2025).
The authors find that if the whole world had emitted as much as the wealthiest 10% of people over 1990-2020, global average temperatures would have risen by 2.9C, instead of 0.61C. If the global population had emissions as large as the wealthiest 0.1%, temperatures would have risen by 12.2C.
Meanwhile, the study calculates that if the whole world had emissions as low as the poorest 50%, global temperatures would have remained close to 1990 levels.
Hot and dry extremes
As greenhouse gas emissions cause the climate to warm, extreme weather events such as heatwaves and droughts are becoming more intense, frequent and long-lasting.
The authors use attribution – a field of climate science that aims to identify the “fingerprint” of global warming on these events – to determine the contribution of the emissions of the world’s wealthiest people to the increasing frequency of heatwaves and droughts.
The authors assess “extremely hot” and “extremely dry” months, defined as the most extreme 1% of months in a pre-industrial climate during the hottest month of the year regionally. (In a pre-industrial climate, only one of each extreme would be expected every 100 years on average.)
The graphs below show the number of additional heatwaves (left) and droughts (right) that have occurred since 1990 due to climate change in different regions of the world.
The full bar shows the total number of additional heatwaves due to human-cased climate change in each region. The green bar shows additional occurrences due to the wealthiest 1%. The green and orange bars combined show the wealthiest 10%.
The numbers in green and orange show how much the wealthiest 1% and 10% of the planet contributed to the extreme, compared to the global average. (For example, an orange number of 7.0 means that the wealthiest 10% of people contributed seven times more to the extreme event than the global average.)
The number of additional heatwaves (left) and droughts (right) that have occurred since 1990 in different regions of the world, caused by the wealthiest 10% (orange) and 1% (green) of the world’s population. The numbers in green and orange show how much more the wealthiest 1% and 10% of the planet contributed to the extreme, compared to the global average. Source: Schöngart et al (2025).
The study finds that an average of 11.5 additional heat events observed in August – the month where the rise in heat extremes is, on average, most pronounced – are attributable to the wealthiest 10%.
It also calculates that emissions from this group resulted in, on average, an additional 2.3 droughts in the Amazon in October – the month with the strongest attributable drying trend in the region.
Highest emitters
The authors also assess the contributions of the wealthiest people to climate extremes on a country level, identifying the US, the EU, China and India as the world’s four highest emitting regions.
The graphic below shows the increase in frequency of one-in-100 year peak summer heat extremes in selected regions attributable to the wealthiest 10% of people (left) and 1% of people (right) in China (red), the US (pink), the EU (peach) and India (blue).
The increase in frequency of one-in-100 year peak summer heat extremes in selected regions that is attributable to the wealthiest 10% of people (left) and 1% of people (right) in China (red), the US (pink), the EU (peach) and India (blue). Source: Schöngart et al (2025).
Emissions from the wealthiest 10% in the US resulted in an average of 1.3 extra heat events globally, the authors find. However, this increase is distributed unevenly across the globe.
For example, the authors find this income group was responsible for the emissions that contributed to 2.7 additional heat events in “heat-affected areas” such as the Amazon and south-east Africa.
Emissions from the wealthiest 10% of people in the EU resulted in an additional 1.5 heatwaves in both the Amazon and south-east Africa.
Meanwhile, the Amazon faces 2.1 more heat extremes in 2020 than in 1990 due to the emissions of the richest 1% in the US, China, EU and India.
While inequalities between one country or region and another are well documented, it should also be noted that “inequalities within developing countries are increasing”, Dr Carl Schleussner, study author and leader of the integrated climate impacts research group at the International Institute for Applied Systems Analysis (IIASA), tells Carbon Brief.
For example, he notes that the paper shows “very high levels” of emissions from “the Chinese middle and upper classes”.
However, he says that many existing global frameworks to address climate change “treat countries as a whole” and fail to “differentiate” between income groups within countries.
Schleussner argues that the study highlights the need for “progressive policies” for climate action, which involve “tackling particularly high emitters” in all countries.
“Quantifying the contribution of individual income groups to global warming and changes in climate extremes is an important step towards targeted policies and further supports climate litigation. Supporting climate injustice with concrete numbers will hopefully help the most vulnerable and least responsible strengthen their case.”
Modelling inequalities
The study uses a range of methods to attribute changes in heat and drought to the emissions of particular wealth groups. To model global greenhouse gas emissions by wealth group, the paper uses a “wealth-based carbon inequality assessment” from a 2022 study.
The study uses income and wealth inequality dataset from the World Inequality Database to track inequality over 1990-2019. It combines economic data with information on per-capita carbon footprints – calculated using “input-output” methodologies combined with data from the “distributional national accounts” project.”
The model considers three factors. The first is private consumption – made up of emissions from the direct use of fossil fuels and emissions embedded into goods and services. The second includes emissions from government spending in that person’s country – such as government administration, public roads or defence. The final component of a person’s carbon footprint is from their investments.
The authors then created a series of “counterfactual” emissions pathways, which imagine the world without the emissions of the wealthiest 10%, 1% and 0.1% of society, respectively. The emissions pathways include CO2, methane and nitrous oxide emissions, expressed as CO2-equivalent.
Lead author Schöngart tells Carbon Brief that including methane in the models is important, because it has “really high potency and near-term warming”. However, she notes that the team needed to make some assumptions about methane emissions – for example, assuming that each income group emits the same relative amount of methane compared to other greenhouse gas emissions.
Using a “simple” climate model called MAGICC, the authors model global average temperatures under these counterfactual emissions pathways. This allows them to calculate how much the planet would have warmed over 1990-2020 without the emissions of the 10%, 1% and 0.1% of society, respectively.
The authors use the global average temperature trends to produce temperature and rainfall data for every land-based grid square on Earth via a climate model emulator called MESMER.
Schöngart tells Carbon Brief that an emulator is “an approximation of an Earth system model” which “allows us to generate incredible amounts of data”, while using less computing power and taking less time to run.
The study authors then use attribution methods to identify how the emissions from the world’s wealthiest members of society have affected the frequency of heatwaves and droughts, by comparing the world as it is to a “counterfactual” world without human-caused climate change.
Earth system scientist Zscheischler praises the methods in the study. He tells Carbon Brief that “the main innovation of work lies in its novel combination of relatively simple emulators that capture the most important relationships between emissions and global warming and changes in extremes”.
He adds that emulators have been evaluated in other studies and are “trustworthy for this type of delicate analysis”.
Prof Wim Thiery – an associate professor at Vrije Universiteit Brussel, who was not involved in the study – also commends the use of emulators. He tells Carbon Brief that “producing the information presented in this study with a suite of full-blown Earth system models is impossible from a computational cost and human effort perspective”.
