Every increment of global warming above 1.5C increases the risk of crossing key tipping points in the Earth system – even if the overshoot is only temporary, says new research.
It is well established that if global temperatures exceed 1.5C above pre-industrial levels, there is a higher risk that tipping points will be crossed.
The new study, published in Nature Communications, investigates the risk of crossing four interconnected tipping points under different “policy-relevant” future emissions scenarios.
The authors investigate the risk of tipping where warming temporarily overshoots 1.5C, but global temperatures are then brought back down using negative emissions technologies. They find that the longer the 1.5C threshold is breached, and the higher the peak temperature, the greater the risk of crossing tipping points.
The most pessimistic scenario in the study sees global warming hit 3.3C by the end of the century – in line with the climate policies of 2020 – before dropping back below 1.5C over 2100-2300. Under this pathway, there is a 45% chance of crossing tipping points by 2300, the authors say.
The authors also warn that if global temperatures rise above 2C, the additional risk of tipping for every extra increment of warming “strongly accelerates”.
For temperatures between 1.5C and 2C, the risk increases by 1-1.5% for every 0.1C increase in overshoot temperature. However, for temperatures above 2.5C, tipping risk increases to 3% per 0.1C of overshoot.
The research “underlines the need for urgent emission cuts now that do not assume substantial carbon dioxide removal later”, a scientist not involved in the study tells Carbon Brief.
Overshoot scenarios
Scientists have warned for decades that as the planet warms, there is an increasing risk that Earth systems will cross “tipping points” – critical thresholds that, if exceeded, could push a system into an entirely new state.
For example, if climate change and human-driven deforestation push the Amazon rainforest past a critical threshold, large parts of the forest could experience “dieback”. This would cause entire sections of lush rainforest to eventually shift to dry savannah.
(See Carbon Brief’s explainer on the nine tipping points that could be crossed as a result of climate change.)
The planet has already warmed by 1.3C above pre-industrial levels, and a recent study warned that five tipping elements – including the collapse of the west Antarctic ice sheet – are already within reach.
That study emphasised the importance of limiting global temperature rise to 1.5C above pre-industrial levels – in line with the 2015 Paris Agreement. It finds that warming of 1.5C would render four climate tipping elements “likely” and a further six “possible”. Meanwhile, 13 tipping elements will be either “likely” or “possible” if the planet warms by 2.6C, as expected under current climate policies.
Many of the potential pathways to limiting global temperature rise to 1.5C by 2100 see the planet initially “overshoot” the threshold before negative emissions methods are used to bring temperatures back down.
The new paper investigates 10 future warming scenarios which run to the year 2300. The authors use the PROVIDE v1.2 emission pathways, which they describe as “an extended version of the illustrative pathways identified” used in the recent sixth assessment of the Intergovernmental Panel on Climate Change (IPCC).
The original scenarios run over 2015-2300, but the authors carried them forward for another 50,000 years by following the temperature trajectory set over 2290-2300. All scenarios stabilise at 1.5C, 1C or pre-industrial temperatures. However, many include overshoots, with peak temperatures ranging from 1.57C to 3.30C.
These scenarios show a range of options for how global temperatures change under these 10 scenarios in the “medium term” – until the year 2300 – as well as in the “long term”, which runs 50,000 years into the future to see how the planet eventually stabilises.
Scenarios that reach net-zero or negative emissions by 2100 and maintain them thereafter are classified as “NZGHG emission scenarios”. The table below gives more detail on each scenario.
| Scenario | Overshoot peak temperature | NZGHG | Stabilisation temperature | Scenario assumptions |
|---|---|---|---|---|
| CurPol-OS-1.5C | 3.30C | Never-NZGHG | 1.5C | Follows current (2020) policies until 2100, then declines |
| ModAct-OS-1.5C | 2.69C | Never-NZGHG | 1.5C | Follows current (2020) pledges (NDCs) until 2100, then declines |
| ModAct-OS-1C | 2.69C | Never-NZGHG | 1.0C | Follows current (2020) pledges (NDCs) until 2100, then declines |
| Ref-1p5 | – | not defined | 1.5C | Reference scenario designed in temperature space |
| SSP5-3.4-OS | 2.35C | No-long-term-NZGHG | 1.5C | Tests system response to rapid emission changes |
| SSP1-1.9 | 1.53C | No-long-term-NZGHG | 1.0C | Sustainable development, no long-term compensation of non-CO2 emissions |
| GS-NZGHG | 1.70C | NZGHG | pre-industrial | Gradual strengthening, returns warming to 1.5 °C by 2215 |
| SP-NZGHG | 1.57C | NZGHG | pre-industrial | Broad shift towards sustainable development |
| Neg-NZGHG | 1.67C | NZGHG | pre-industrial | Returns warming to 1.5 °C by 2100 with heavy CDR deployment |
| Neg-OS-OC | 1.67C | NZGHG | pre-industrial | Returns warming to 1.5 °C by 2100 with heavy CDR deployment |
Table showing the 10 scenarios used in this study. Source: Möller et al (2024).
There is quite a range between the 10 pathways.
At the high end, the “CurPol-OS-1.5C” scenario sees a continuation of the global climate policies implemented in 2020 until the year 2100, with warming peaking at 3.3C. It then sees a decline in global temperature until reaching a stabilisation of 1.5C by the year 2300.
At the low end, “Neg-OS-0C” scenario initially overshoots 1.5C to 1.67C, but then returns warming to 1.5C by 2100 using “heavy carbon dioxide removal deployment”. It also then sees average global temperatures drop to pre-industrial levels by the year 2300.
In the middle, the Ref-1p5 scenario is the only one that does not include an overshoot, instead stabilising quickly at 1.5C.
The chart below shows greenhouse gas emissions (top) and corresponding global temperature changes (bottom) associated with each scenario, identified by the different-coloured lines. The bottom chart illustrates the range in how quickly the pathways return to 1.5C or below.
Dr David McKay is a research impact fellow at the University of Exeter’s Global Systems Institute, who has published extensively on climate tipping points, but was not involved in this study.
He also notes that some of the scenarios shown in this study “may not be possible”, because there is debate about whether or not “the substantial carbon dioxide removal needed for large overshoots is feasible”.
Cascades
Many Earth systems are interlinked, so crossing one tipping point can increase the likelihood of crossing others. This is often described as a “domino effect” or “tipping cascade”.
The study focuses on four interconnected tipping points – collapse of the Greenland ice sheet and west Antarctic ice sheet, shutdown of the Atlantic Meridional Overturning Circulation and dieback of the Amazon rainforest.
Annika Högner is a researcher at the Potsdam Institute for Climate Impact Research (PIK) and co-lead author on the study. She tells Carbon Brief these four tipping points were chosen because they “play a significant role in the functioning of the Earth system” and “their tipping would have severe global impacts”.
The graphic below shows how the tipping points interact with each other. A “+” symbol indicates that crossing one tipping point can destabilise another. For example, a collapse of the Greenland ice sheet makes the AMOC more likely to shut down, as a result of the sudden influx of freshwater into the north Atlantic Ocean. A “±” symbol indicates that the relationship between two tipping points is uncertain.
A “-” symbol indicates that crossing one tipping point stabilises another. Högner tells Carbon Brief that the interaction between the Greenland ice sheet and AMOC is the only stabilising interaction in this study. She explains that if the AMOC were to cross a tipping point, “we [would] expect to see strong cooling in the northern hemisphere”, which will contribute to stabilising the Greenland ice sheet.
Earth system models “often don’t resolve tipping processes very well”, making them less suited to modelling full tipping cascades, Högner tells Carbon Brief.
Instead, she explains that the authors developed a “conceptual model”. This model does not attempt to simulate the entire Earth system, but instead just models the likelihood of tipping at different temperatures, based on existing knowledge about tipping elements from other studies.
The model takes temperature trajectories as an input and gives the state of the tipping elements after a specified time – that is, whether or not the element has tipped – as an output.
Importantly, these models include “hysteresis” – a feature of tipping systems, in which a system that has moved to a different state does not easily move back to the original state even if temperatures are reduced again.
Tipping risk
The authors use their conceptual model to calculate “tipping risk” under the 10 future warming scenarios. Högner tells Carbon Brief that tipping risk “refers to the model of all four interacting tipping elements analysed in the study”. For example, a 50% tipping risk means there is a 50% chance that at least one of the four climate elements will tip.
The top row of the graphic below shows the risk of tipping in the year 2300 (left) and in 50,000 years from now (right). Bars placed higher up indicate a greater likelihood of tipping. The dot shows the average value for each data point, while the bars show the 10-90% range.
The text on the right hand side gives likelihood levels in the calibrated language used by the IPCC: very likely means a likelihood of 90-100%, likely is 66-100%, about as likely as not is 33-66%; unlikely is 0-33%; and very unlikely is 0-10%.
The middle row shows the peak temperature under each scenario (left) and stabilisation temperature (right). The bottom row shows how long temperatures overshoot before stabilising in each scenario.
The longer the 1.5C threshold is breached for, and the higher the peak temperature is, the greater the risk of crossing tipping points by the year 2300, the study shows.
The authors find the greatest risk of crossing tipping points in the CurPol-OS-1.5C scenario (red), which follows the climate policies of 2020 until the year 2100 and then reaches 1.5C by 2300, as this scenario has the greatest overshoot temperature and duration.
Under this scenario, there is a 45% tipping risk by 2300 and a 76% chance in 50,000 years, according to the paper.
The five pathways that do not return warming to 1.5C by the year 2100 have the greatest medium-term risks, and those with less than 0.1C overshoot have the lowest medium-term risks.
In the long-term – looking to the next 50,000 years – the authors find that stabilisation temperature is “one of the decisive variables for tipping risks”. They find that even in the Ref1p5 scenario – which sees global temperatures stabilise at 1.5C without any overshoot – there is a 50% risk of the system tipping over the next 50,000 years.
The results “illustrate that a global mean temperature increase of 1.5C is not ‘safe’ in terms of planetary stability, but must be seen as an upper limit”, the study warns.
Högner tells Carbon Brief that the paper “underlines the importance of adhering to the Paris Agreement temperature goal”.
Tessa Möller – a researcher at the International Institute for Applied Systems Analysis (IIASA) and co-lead author on the paper – tells Carbon Brief that “we have a wide portfolio of technologies available” to limit warming to 1.5C, and just need to “implement” them.
However, she also highlights the “large credibility gap” between pledges from individual countries and the policies they have actually implemented. She tells Carbon Brief that not only do we need “stronger pledges”, but it is also essential that countries follow through on them.
Long-term climate
The authors also explore the risk of each individual tipping point being crossed in different scenarios.
The plot below shows the tipping risk by 2300 under different scenarios, at different temperatures, on the left. Each colour represents one scenario. Dots positioned further to the right indicate a greater peak temperature and dots positioned higher up indicate a greater tipping risk.
The plot on the right shows the percentage change in tipping risk for every additional 0.1C of overshoot, for different peak global temperatures, for the Amazon (cross), AMOC (plus), West Antarctic ice sheet (black dot) Greenland Ice sheet (square) and overall (yellow dot).
The authors find that AMOC collapse and Amazon dieback would likely be the first components to tip. This could be in the next 15-300 years and 50-200 years, respectively, depending on the scenario, they find.
Meanwhile, the Greenland and west Antarctic ice sheets have tipping timescales of 1,000-15,000 years and 500-13,000 years, respectively.
However, they note that as temperatures increase, the relative risk of each element tipping changes. The graph shows that while AMOC is the main driver of tipping risk at lower temperatures, the Amazon becomes the main driver once global temperatures exceed 2C.
Finally, they find that as global temperatures rise, the risk of tipping accelerates. Overall, tipping risk increases by 1-1.5% per 0.1C increase in overshoot temperature, for temperatures below 2C, according to the study. However, above 2.5C, tipping risk increases to 3% per 0.1C increase overshoot.
McKay notes that there are some limitations in the study. For example, he notes that the paper “has to rely on tipping threshold and timescale estimates with often wide ranges and sometimes low confidence, while tipping interaction estimates are based on dated expert judgement”.
However, he adds:
“This work makes it clear that every fraction of warming increases the chance of tipping points, even if global temperature subsequently falls, and underlines the need for urgent emission cuts now that do not assume substantial carbon dioxide removal later.”
The post ‘Every 0.1C’ of overshoot above 1.5C increases risk of crossing tipping points appeared first on Carbon Brief.
‘Every 0.1C’ of overshoot above 1.5C increases risk of crossing tipping points
Greenhouse Gases
Cropped 13 August 2025: Fossil-fuelled bird decline; ‘Deadly’ wildfires; Empty nature fund
We handpick and explain the most important stories at the intersection of climate, land, food and nature over the past fortnight.
This is an online version of Carbon Brief’s fortnightly Cropped email newsletter. Subscribe for free here.
Key developments
‘Deadly’ wildfires
WINE BRAKE: France experienced its “largest wildfire in decades”, which scorched more than 16,000 hectares in the country’s southern Aude region, the Associated Press said. “Gusting winds” fanned the flames, Reuters reported, but local winemakers and mayors also “blam[ed] the loss of vineyards”, which can act as a “natural, moisture-filled brake against wildfires”, for the fire’s rapid spread. It added that thousands of hectares of vineyards were removed in Aude over the past year. Meanwhile, thousands of people were evacuated from “deadly” wildfires in Spain, the Guardian said, with blazes ongoing in other parts of Europe.
MAJOR FIRES: Canada is experiencing its second-worst wildfire season on record, CBC News reported. More than 7.3m hectares burned in 2025, “more than double the 10-year average for this time of year”, the broadcaster said. The past three fire seasons were “among the 10 worst on record”, CBC News added. Dr Mike Flannigan from Thompson Rivers University told the Guardian: “This is our new reality…The warmer it gets, the more fires we see.” Elsewhere, the UK is experiencing a record year for wildfires, with more than 40,000 hectares of land burned so far in 2025, according to Carbon Brief.
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WESTERN US: The US state of Colorado has recorded one of its largest wildfires in history in recent days, the Guardian said. The fire “charred” more than 43,300 hectares of land and led to the temporary evacuation of 179 inmates from a prison, the newspaper said. In California, a fire broke out “during a heatwave” and burned more than 2,000 hectares before it was contained, the Los Angeles Times reported. BBC News noted: “Wildfires have become more frequent in California, with experts citing climate change as a key factor. Hotter, drier conditions have made fire seasons longer and more destructive.”
FIRE FUNDING: “Worsening fires” in the Brazilian Amazon threaten new rainforest funding proposals due to be announced at the COP30 climate summit later this year, experts told Climate Home News. The new initiatives include the Tropical Forests Forever Facility, which the outlet said “aims to generate a flow of international investment to pay countries annually in proportion to their preserved tropical forests”. The outlet added: “If fires in the Amazon continue to worsen in the years to come, eligibility for funding could be jeopardised, Brazil’s environment ministry acknowledged.”
Farming impacts
OUT OF ORBIT: US president Donald Trump moved to “shut down” two space missions which monitor carbon dioxide and plant health, the Associated Press reported. Ending these NASA missions would “potentially shu[t] off an important source of data for scientists, policymakers and farmers”, the outlet said. Dr David Crisp, a retired NASA scientist, said the missions can detect the “glow” of plant growth, which the outlet noted “helps monitor drought and predict food shortages that can lead to civil unrest and famine”.
FARM EXTREMES: Elsewhere, Reuters said that some farmers are considering “abandoning” a “drought-hit” agricultural area in Hungary as “climate change cuts crop yields and reduces groundwater levels”. Scientists warned that rising temperatures and low rainfall threaten the region’s “agricultural viability”, the newswire added. Meanwhile, the Premium Times in Nigeria said that some farmers are “harvest[ing] crops prematurely” due to flooding fears. A community in the south-eastern state of Imo “has endured recurrent floods, which wash away crops and incomes alike” over the past decade, the newspaper noted.
SECURITY RISKS: Food supply chains in the UK face “escalating threats from climate impacts and the migration they are triggering”, according to a report covered by Business Green. The outlet said that £3bn worth of UK food imports originated from the 20 countries “with the highest numbers of climate-driven displacements” in 2024, based on analysis from the Energy and Climate Intelligence Unit. The analysis highlighted that “climate impacts on food imports pose a threat to UK food security”. Elsewhere, an opinion piece in Dialogue Earth explored how the “role of gender equity in food security remains critically unaddressed”.
Spotlight
Fossil-fuelled bird decline
This week, Carbon Brief covers a new study tracing the impact of fossil-fuelled climate change on tropical birds.
Over the past few years, biologists have recorded sharp declines in bird numbers across tropical rainforests – even in areas untouched by humans – with the cause remaining a mystery.
A new study published this week in Nature Ecology and Evolution could help to shed light on this alarming phenomenon.
The research combined ecological and climate attribution techniques for the first time to trace the fingerprint of fossil-fuelled climate change on declining bird populations.
It found that an increase in heat extremes driven by climate change has caused tropical bird populations to decline by 25-38% in the period 1950-2020, when compared to a world without warming.
In their paper, the authors noted that birds in the tropics could be living close to their “thermal limits”.
Study lead author Dr Maximilian Kotz, a climate scientist at the Barcelona Supercomputing Center in Spain, explained to Carbon Brief:
“High temperature extremes can induce direct mortality in bird populations due to hyperthermia and dehydration. Even when they don’t [kill birds immediately], there’s evidence that this can then affect body condition which, in turn, affects breeding behaviour and success.”
Conservation implications
The findings have “potential ramifications” for commonly proposed conservation strategies, such as increasing the amount of land in the tropics that is protected for nature, the authors said. In their paper, they continued:
“While we do not disagree that these strategies are necessary for abating tropical habitat loss…our research shows there is now an additional urgent need to investigate strategies that can allow for the persistence of tropical species that are vulnerable to heat extremes.”
In some parts of the world, scientists and conservationists are looking into how to protect wildlife from more intense and frequent climate extremes, Kotz said.
He referenced one project in Australia which is working to protect threatened wildlife following periods of extreme heat, drought and bushfires.
Prof Alex Pigot, a biodiversity scientist at University College London (UCL), who was not involved in the research, said the findings reinforced the need to systematically monitor the impact of extreme weather on wildlife. He told Carbon Brief:
“We urgently need to develop early warning systems to be able to anticipate in advance where and when extreme heatwaves and droughts are likely to impact populations – and also rapidly scale up our monitoring of species and ecosystems so that we can reliably detect these effects.”
There is further coverage of this research on Carbon Brief’s website.
News and views
EMPTY CALI FUND: A major voluntary fund for biodiversity remains empty more than five months after its launch, Carbon Brief revealed. The Cali Fund, agreed at the COP16 biodiversity negotiations last year, was set up for companies who rely on nature’s resources to share some of their earnings with the countries where many of these resources originate. Big pharmaceutical companies did not take up on opportunities to commit to contributing to the fund or be involved in its launch in February 2025, emails released to Carbon Brief showed. Just one US biotechnology firm has pledged to contribute to the fund in the future.
LOSING HOPE: Western Australia’s Ningaloo reef – long considered a “hope spot” among the country’s coral reefs for evading major bleaching events – is facing its “worst-ever coral bleaching”, Australia’s ABC News reported. The ocean around Ningaloo has been “abnormally” warm since December, resulting in “unprecedented” bleaching and mortality, a research scientist told the outlet. According to marine ecologist Dr Damian Thomson, “up to 50% of the examined coral was dead in May”, the Sydney Morning Herald said. Thomson told the newspaper: “You realise your children are probably never going to see Ningaloo the way you saw it.”
‘DEVASTATION BILL’: Brazil’s president, Luiz Inácio Lula da Silva, signed a “contentious” environmental bill into law, but “partially vetoed” some of the widely criticised elements, the Financial Times reported. Critics, who dubbed it the “devastation bill”, said it “risked fuelling deforestation and would harm Brazil’s ecological credentials” just months before hosting the COP30 climate summit. The newspaper said: “The leftist leader struck down or altered 63 of 400 provisions in the legislation, which was designed to speed up and modernise environmental licensing for new business and infrastructure developments.” The vetoes need to be approved by congress, “where Lula lacks a majority”, the newspaper noted.
RAINFOREST DRILLING: The EU has advised the Democratic Republic of the Congo (DRC) against allowing oil drilling in a vast stretch of rainforest and peatland that was jointly designated a “green corridor” earlier this year, Climate Home News reported. In May, the DRC announced that it planned to open the conservation area for drilling, the publication said. A spokesperson for the European Commission told Climate Home News that the bloc “fully acknowledges and respects the DRC’s sovereign right to utilise its diverse resources for economic development”, but that it “highlights the fact that green alternatives have facilitated the protection of certain areas”.
NEW PLAN FOR WETLANDS: During the 15th meeting of the Ramsar Convention on Wetlands, held in Zimbabwe from 23 to 31 July, countries agreed on the adoption of a new 10-year strategic plan for conserving and sustainably using the world’s wetlands. Down to Earth reported that 13 resolutions were adopted, including “enhancing monitoring and reporting, capacity building and mobilisation of resources”. During the talks, Zimbabwe’s environment minister announced plans to restore 250,000 hectares of degraded wetlands by 2030 and Saudi Arabia entered the Convention on Wetlands. Panamá will host the next COP on wetlands in July 2028.
MEAT MADNESS: DeSmog covered the details of a 2021 public relations document that revealed how the meat industry is trying to “make beef seem climate-friendly”. The industry “may have enlisted environmental groups to persuade people to ‘feel better’ about eating beef”, the outlet said, based on this document. The strategy was created by a communications agency, MHP Group, and addressed to the Global Roundtable for Sustainable Beef. One of the key messages of the plan was to communicate the “growing momentum in the beef industry to protect and nurture the Earth’s natural resources”. MHP Group did not respond to a request for comment, according to DeSmog.
Watch, read, listen
MAKING WAVES: A livestream of deep-sea “crustaceans, sponges and sea cucumbers” has “captivated” people in Argentina, the New York Times outlined.
BAFFLING BIRDS: The Times explored the backstory to the tens of thousands of “exotic-looking” parakeets found in parks across Britain.
PLANT-BASED POWER: In the Conversation, Prof Paul Behrens outlined how switching to a plant-based diet could help the UK meet its climate and health targets.
MARINE DISCRIMINATION: Nature spoke to a US-based graduate student who co-founded Minorities in Shark Science about her experiences of racism and sexism in the research field.
New science
- Applying biochar – a type of charcoal – to soils each year over a long period of time can have “sustained benefits for crop yield and greenhouse gas mitigation”, according to a Proceedings of the National Academy of Sciences study.
- New research, published in PLOS Climate, found that nearly one-third of highly migratory fish species in the US waters of the Atlantic Ocean have “high” or “very high” vulnerability to climate change, but the majority of species have “some level of resilience and adaptability”.
- A study in Communications Earth & Environment found a “notable greening trend” in China’s wetlands over 2000-23, with an increasing amount of carbon being stored in the plants growing there.
In the diary
- 18-29 August: Second meeting of the preparatory commission for the Agreement on Marine Biological Diversity of Areas beyond National Jurisdiction | New York
- 24-28 August: World Water Week | Online and Stockholm, Sweden
- 26-29 August: Sixth forum of ministers and environment authorities of Asia Pacific | Nadi, Fiji
Cropped is researched and written by Dr Giuliana Viglione, Aruna Chandrasekhar, Daisy Dunne, Orla Dwyer and Yanine Quiroz. Please send tips and feedback to cropped@carbonbrief.org
The post Cropped 13 August 2025: Fossil-fuelled bird decline; ‘Deadly’ wildfires; Empty nature fund appeared first on Carbon Brief.
Cropped 13 August 2025: Fossil-fuelled bird decline; ‘Deadly’ wildfires; Empty nature fund
CCL submits a formal comment on EPA’s proposed endangerment finding rollback
By Dana Nuccitelli, CCL Research Manager
On July 29, the EPA proposed to rescind its 2009 endangerment finding that forms the basis of all federal climate pollution regulations.
Without the endangerment finding, the EPA may not be allowed or able to regulate greenhouse gas pollution from sources like power plants or vehicle tailpipes, as they have done for years. News coverage has framed this as a “radical transformation” and a “bid to scrap almost all pollution regulations,” so it has appropriately alarmed many folks in the climate and environment space.
At CCL, we focus our efforts on working with Congress to implement durable climate policies, and so we don’t normally take actions on issues like this that relate to federal agencies or the courts. Other organizations focus their efforts on those branches of the government and are better equipped to spearhead this type of moment, and we appreciate those allies.
But in this case, we did see an opportunity for CCL’s voice — and our focus on Congress — to play a role here. We decided to submit a formal comment on this EPA action for two reasons.
First, this decision could have an immense impact by eliminating every federal regulation of climate pollutants in a worst case scenario. Second, this move relates to our work because the EPA is misinterpreting the text and intent of laws passed by Congress. Our representatives have done their jobs by passing legislation over the past many decades that supports and further codifies the EPA’s mandate to regulate climate pollution. That includes the Clean Air Act, and more recently, the Inflation Reduction Act. We at CCL wanted to support our members of Congress by making these points in a formal comment.
There has been a tremendous public response to this action. In just over one week, the EPA already received over 44,000 public comments on its decision, and the public comment period will remain open for another five weeks, until September 15.
To understand more about the details and potential outcomes of the EPA’s actions, read my article on the subject at Yale Climate Connections, our discussion on CCL Community, and CCL’s formal comment, which represents our entire organization. As our comment concludes,
“In its justifications for rescinding the 2009 endangerment finding, the Reconsideration has misinterpreted the text of the Clean Air Act, Congress’ decadeslong support for the EPA’s mandate to regulate greenhouse gas emissions from motor vehicles and other major sources, and the vast body of peer-reviewed climate science research that documents the increasingly dangerous threats that those emissions pose to Americans’ health and welfare. Because the bases of these justifications are fundamentally flawed, CCL urges the EPA to withdraw its ill-conceived Reconsideration of the 2009 endangerment finding. The EPA has both the authority and the responsibility to act. Americans cannot afford a retreat from science, law, and common sense in the face of a rapidly accelerating climate crisis.”
After the EPA responds to the public comment record and finalizes its decision, this issue will ultimately be decided by the Supreme Court several years from now.
In the meantime, CCL will continue to focus our efforts on areas where we can make the biggest difference in preserving a livable climate. Right now, that involves contacting our members of Congress to urge them to fully fund key climate and energy programs and protect critical work at the National Oceanic and Atmospheric Administration (NOAA), National Aeronautics and Space Administration (NASA), and Department of Energy. We’ve set an ambitious goal of sending 10,000 messages to our members of Congress, so let’s all do what CCL does best and make our voices heard on this critical issue.
This action by the EPA also reminds us that federal regulations are fragile. They tend to change with each new administration coming into the White House. Legislation passed by Congress – especially when done on a bipartisan basis – is much more durable. That’s why CCL’s work, as one of very few organizations engaging in nonpartisan advocacy for long-lasting climate legislation, is so critical.
That’s especially true right now when we’re seeing the Trump administration slam shut every executive branch door to addressing climate change. We need Congress to step up now more than ever to implement durable solutions like funding key climate and energy programs, negotiating a new bipartisan comprehensive permitting reform bill, implementing healthy forest solutions like the Fix Our Forests Act, and advancing conversations about policies to put a price on carbon pollution. Those are the kinds of effective, durable, bipartisan climate solutions that CCL is uniquely poised to help become law and make a real difference in preserving a livable climate.
For other examples of how CCL is using our grassroots power to help ensure that Congress stays effective on climate in this political landscape, see our full “Holding the Line on Climate” blog series.
The post Holding the line on climate: EPA appeared first on Citizens' Climate Lobby.
Greenhouse Gases
Analysis: England’s most ethnically diverse areas are 15 times more likely to face extreme heat
Neighbourhoods in England that are home to the most minority-ethnic people are 15 times more likely to face extreme heat than the least diverse areas, according to Carbon Brief analysis.
People with the lowest carbon footprints – who therefore contribute less to climate change – are also more likely to live in areas that experience high temperatures.
This is based on Carbon Brief analysis that combines satellite data on heat exposure with data on per-capita emissions, ethnicity and levels of deprivation across England.
Thousands of deaths in the UK have been attributed to heat in recent years and the threat is expected to grow as climate change worsens.
But heat is also felt differently across the country, with certain groups both more exposed and more vulnerable to dangerous temperatures.
Broadly, the analysis shows how those subject to the “urban heat island” effect in English cities, often in low-quality housing and with little access to green space, are more likely to experience extreme heat.
Experts tell Carbon Brief that policymaking should reflect the reality of climate change “amplifying” inequalities across society and provide help to those most in need, such as more heat-resilient social housing.
Heat threat
As greenhouse gas emissions and global temperatures rise, more people in the UK are likely to become ill or even die due to extreme heat.
Heat has killed around 6,000 people in England over the past three years, according to government figures. This is roughly double the number killed over the same period between 2016 and 2018.
Scientists have repeatedly linked extreme heat – and the resulting deaths – to climate change.
In June 2025 alone, more than 260 people died in London due to a heatwave, according to a recent attribution study that linked the event to climate change.
Government advisor the Climate Change Committee (CCC) estimates that the number of heat-related fatalities in the UK each year is set to triple by 2050, without adaptation measures.
Around half of homes in the country are already at risk of overheating and the CCC expects this to reach 90%, if global temperatures rise by 2C above pre-industrial levels.
However, these risks will not fall equally across society, with children, the elderly and disabled people more vulnerable to heat-related illness. There is also evidence that poorer communities and people of colour are more vulnerable to extreme heat.
Such communities also tend to have lower carbon footprints than those that are whiter and wealthier.
This fits with the broader concept of climate justice, which describes how people who are least responsible for climate change often end up bearing the brunt of its effects.
Carbon footprints
To investigate these issues, Carbon Brief combined detailed satellite data on heat exposure across England, provided by 4 Earth Intelligence, with neighbourhood-level carbon footprints compiled by the Centre for Research in Energy Demand Solutions (CREDS).
The CREDS dataset provides estimates of per-person carbon footprints, indicating how much the average person in each neighbourhood is contributing to climate change.
Due to data availability, this analysis focuses exclusively on England, the nation that experiences the most extreme heat in the UK.
Every neighbourhood is scored based on its “heat hazard”, meaning the likelihood that it will experience higher relative temperatures during hot weather, compared to surrounding areas.
The analysis then zooms in on the 10% worst-affected neighbourhoods in England. These neighbourhoods have a heat hazard score of 4 or 5, meaning that they face higher exposure to heat than 90% of areas around the country. (For a full explanation, see Methodology.)
The figure below shows that neighbourhoods with lower carbon footprints are twice as likely to face high heat hazard scores than areas with higher carbon footprints.
Specifically, it shows that 13.4% of neighbourhoods with the lowest carbon footprints are among the English areas most exposed to heat hazards. In contrast, only 7.0% of neighbourhoods with the highest carbon footprint are among the most heat-exposed areas.
Neighbourhoods in England with lower carbon footprints are often in dense, urban areas, where people tend to be less reliant on cars and more likely to live in energy-efficient flats.
Areas with higher carbon footprints are commonly found in rural areas, where travelling by car can be a necessity due to limited public transport.
Also, particularly in south-east England, people in these rural neighbourhoods are often wealthier, meaning they spend more money on flights and other high-emitting luxuries.
Ethnicity and deprivation
Carbon Brief also analysed the heat threat facing deprived neighbourhoods in England and those that are home to more people of colour.
Information about how many people identify as black, Asian and other minority ethnicities in each neighbourhood is based on 2021 census data, via the Office for National Statistics.
As the chart below shows, there is a clear correlation between the number of people of colour living in a neighbourhood and the likelihood of it facing extreme heat during periods of hot weather.
The most ethnically diverse neighbourhoods – where roughly half or more of the population are people of colour – are 15 times more likely to have high heat hazard scores than the least ethnically diverse neighbourhoods, where almost everyone is white.
Among the most diverse areas are parts of Newham in east London, Saltley in Birmingham and Spinney Hills in Leicester, all of which are inner-city areas.
The least diverse neighbourhoods range from coastal parts of Redcar and Cleveland in North Yorkshire to the rural villages of south Somerset. None of England’s hottest 1% of neighbourhoods are in this bracket.
Additionally, Carbon Brief assessed the relationship between levels of poverty and heat risk, based on England’s indices of deprivation dataset. This covers several measures of deprivation, including income, employment and health.
People living in the most deprived English neighbourhoods are more than three times as likely to face high levels of heat hazard as those in the least deprived neighbourhoods, as shown in the figure below.
The correlation between poverty and extreme heat is less extreme than the one between heat exposure and ethnicity.
While many of England’s most deprived areas are in cities, they are also clustered in some rural and coastal areas – such as parts of Cornwall and Lincolnshire – which tend to be cooler.
Urban heat island
The key phenomenon captured by this analysis is the urban heat island effect. This describes how cities – and particularly areas with dense buildings, roads and stretches of concrete that absorb heat – tend to be hotter than the surrounding countryside.
Cities such as London, Manchester and Birmingham have reached temperatures up to 5C hotter than the surrounding areas in recent decades, due to this effect.
The diagram below shows how air flows circulate between rural and urban areas, forming “heat domes” over cities.
Inner-city areas in England are also home to many people facing high levels of deprivation, as well as large black and Asian communities. Many of these communities are therefore exposed to more dangerous temperatures due to the urban heat island effect.
Access to green spaces, even within cities, also influences exposure to the urban heat island effect. Research has shown how people in deprived areas and people of colour – particularly black people – are more likely to live in areas with less access to green spaces.
There is already extensive scientific literature that uses satellite data to demonstrate the urban heat island effect in cities and other locations.
A number of studies have also used this data to show how people of colour and those living in poverty are more exposed to extreme heat. Much of this research has come from the US, where historic housing inequalities have created stark patterns of segregation in many cities.
A project led by environmental policy researcher Dr Angel Hsu of the University of North Carolina-Chapel Hill shows how, globally, “cities are burdening lower-income populations with higher heat exposure”, as she tells Carbon Brief.
Given this, Hsu adds that “it’s not surprising to us to see similar disproportionate exposure patterns among UK neighbourhoods”.
Other researchers tell Carbon Brief that it is important to be wary of satellite data, as it does not precisely capture the air temperatures experienced in these neighbourhoods.
Dr Charles Simpson, who researches the health and economic impacts of climate change at University College London (UCL), notes:
“Satellite-measured surface temperature does not always correlate with the air temperature – what you are measuring includes a lot of road surfaces and rooftops. The air temperature is thought to be more directly relevant to people’s health and their cooling needs.”
Previous research has found that satellite data can therefore overestimate the urban heat island effect compared to data from weather stations.
These stations, however, are not widespread enough to allow comparisons with detailed neighbourhood data. They are particularly lacking in more deprived areas in England, potentially making measurements there less reliable.
Other scientists tell Carbon Brief that, in the absence of a comprehensive ground monitoring network, satellite measurements can serve as a stand-in to estimate heat exposure. Dr Chloe Brimicombe, an extreme-heat researcher based at the University of Graz, explains:
“Although it’s not a good indicator of perceived [temperature], it is a good indicator of what regions are most built up and have the environments that are most vulnerable to heat.”
‘Amplifying’ inequalities
There is a growing body of evidence gathered by activists, scientists and local governments around the UK revealing the unequal burden of climate change.
Dr Charles Ogunbode, an assistant professor of applied psychology at the University of Nottingham who specialises in how people experience climate change, tells Carbon Brief that this kind of data helps to clarify the links between climate change and inequalities:
“We can’t avoid dealing with the issue of social inequalities and climate change is just basically amplifying those things. It’s highlighting them, it’s revealing them. So whatever policies we put in place – be it in the health sector, be it in the climate sector – addressing those inequalities has to be an essential part of whatever those responses are.”
There are many factors influencing how people experience heat that are not captured in Carbon Brief’s analysis.
Previous work by researchers at the University of Manchester and Friends of the Earth has explored this issue, including an analysis of more than 40 indicators that could make neighbourhoods more “socially vulnerable” to heat.
This reveals similar outcomes, with people of colour and those contributing the least to climate change generally more vulnerable to its impacts.
One of the biggest factors that contributes to people’s exposure to heat extremes in the UK is the country’s housing stock, which is “not fit for the future”, according to the CCC.
UK homes have generally not been built for hotter conditions and poorer people are more likely to live in badly adapted housing. Those living in small homes, flats and social housing in England all “suffer significantly more overheating” during heatwaves, according to one study.
Dr Giorgos Petrou, a researcher in building physics modelling at UCL, tells Carbon Brief that it is also vital to consider whether households have the ability to adapt to climate change. “Amongst other factors, their capability will depend on their financial means and whether they own or rent their home,” he says.
Experts tell Carbon Brief that the government should act across its policy agenda to not only address extreme heat, but also support those who are most affected by it. This could involve expanding tree cover and renovating old social housing stock in at-risk communities.
Emma Howard Boyd, a former chair of the Environment Agency who also chaired the London Climate Resilience Review, tells Carbon Brief:
“I do think that with [the Labour] government focusing on house building and retrofit, this is a fantastic opportunity to get this right…For those communities that have had the least impact on the environment and climate change themselves.”
Methodology
This analysis collates several datasets that cover England at a neighbourhood level, with “neighbourhoods” defined as lower-layer super output areas (LSOAs). These are small statistical areas used by the UK government, covering populations of about 1,500-3,000 people. There are 33,755 LSOAs in England.
Data on vulnerability to heat comes from 4 Earth Intelligence (4EI), which analyses land surface temperature to generate “heat hazard” information at a 30m resolution. This detailed information has been converted into LSOAs by 4EI.
Heat hazard scores are calculated by 4EI, based on the likelihood that a given neighbourhood will experience high temperatures during hot weather, relative to the surrounding area.
Each score corresponds to a different percentile of English neighbourhoods. The bar below shows the percentage breakdown across all LSOAs in England.
The two hottest scores – those coloured in red – correspond to the 10% of English neighbourhoods that have higher heat hazard scores than the remaining 90%.
For simplicity, Carbon Brief’s analysis focuses on the red bars above, meaning neighbourhoods in either the top 90th-99th percentile or 99th percentile of heat hazard. (Neighbourhoods in the 90th-99th percentile have higher heat hazard scores than 90% of areas in England. Neighbourhoods in the 99th percentile have higher heat hazard scores than 99% of areas.)
It shows how these two scores are overrepresented in LSOAs that have lower carbon footprints, more diverse communities and higher levels of deprivation.
Carbon-footprint data is from the CREDS “place-based carbon calculator”, which estimates the average per-person carbon footprint for every LSOA in England. It accounts for emissions-producing activities ranging from electricity use to “consumption of goods and services”.
CREDS assigns the grades “A” to “F” (low carbon footprint to high carbon footprint) to neighbourhoods. Carbon Brief has based its carbon-footprint analysis on these grades.
LSOA-level data on black, Asian and other minority-ethnic populations comes from 2021 census data. English LSOAs were broken down into deciles, based on the percentage of the population that identified as non-white ethnicities.
The lowest decile covered the tenth of LSOAs with between 0 and 2% non-white minority-ethnic populations and the highest covered the tenth with more than 51%.
England’s indices of multiple deprivation dataset also includes LSOA-level information. It provides relative measures of deprivation for LSOAs in England, based on income, employment, education, health, crime, living environment and barriers to housing and services. Carbon Brief broke the LSOAs down into deciles based on the total deprivation scores, from the most deprived to the least deprived.
The post Analysis: England’s most ethnically diverse areas are 15 times more likely to face extreme heat appeared first on Carbon Brief.
Analysis: England’s most ethnically diverse areas are 15 times more likely to face extreme heat
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