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The rate at which atmospheric CO2 is increasing is now outpacing the pathways set out by the Intergovernmental Panel on Climate Change (IPCC) that limit global warming to 1.5C.

This is what the latest data shows from the Mauna Loa observatory in Hawaii, where measurements of CO2 levels in the atmosphere have been collected for more than 60 years.

In 2024, the rise in atmospheric CO2 was one of the fastest on record.

Emissions of CO2 and other greenhouse gases from human activity have so far caused human-caused global warming to reach about 1.3C above pre-industrial levels.

If warming is to be limited to 1.5C, as set out in the Paris Agreement, the build-up of CO2 and other greenhouse gases in the atmosphere will need to slow to a halt and then go into reverse.

And, yet, the rise in atmospheric CO2 concentrations is still showing no signs of slowing.

Pathways to 1.5C

The third working group report of the IPCC’s sixth assessment report (AR6), published in 2022, presented a set of seven “illustrative pathways” that highlight how different mitigation choices across major economic sectors translate into future greenhouse gas emissions and global temperatures.

In the three most-ambitious pathways, global warming has a 50% chance of either staying below 1.5C, or overshooting it by only 0.1C (for up to several decades) before then returning to below 1.5C:

  • Shifting pathways (IMP-SP): Illustrates mitigation in the context of a broader shift towards sustainable development, including by reducing inequality and with a phase-out of fossil fuels.
  • Low demand (IMP-LD): Illustrates a strong emphasis on energy-demand reductions, and with a phase-out of fossil fuels.
  • Renewables (IMP-Ren): Illustrates a future with a heavy reliance on renewable energy.

As the table below shows, the build-up of atmospheric CO2 in these three scenarios slows from the 2010s average of 2.41 parts per million per year (ppm/year) to 1.33-1.79ppm/year in the 2020s.

It then slows still further and goes into reverse either in the 2030s or 2040s – in other words, the level of CO2 in the atmosphere actually begins to fall.

Decade Projected average CO2 rise (ppm/year) in scenarios limiting global warming to1.5C
C1-IMP-LD C1-IMP-REN C1-IMP-SP
2020s 1.33 1.75 1.79
2030s -0.14 0.13 0.57
2040s -0.53 -0.46 -0.7
2050s -0.65 -0.61 -0.41

Large CO2 rise in 2024

Yet, not only are atmospheric CO2 concentrations still rising, the rate of rise is accelerating.

The build-up of CO2 in the atmosphere has been monitored at the Mauna Loa observatory in Hawaii since 1958.

As illustrated by the iconic Keeling Curve below, the increase has been accelerating over the decades (blue line) due to ongoing emissions of CO2 from burning fossil fuels and changing land use.

So while the curve needs to rapidly bend in the other direction to hold warming to 1.5C (light red line), the rate of rising CO2 marches onwards and upwards.

chart

Monthly CO2 concentrations at Mauna Loa

Monthly CO2 concentrations at Mauna Loa from observations up to 2024 (blue) and the IPCC C1-IMP-SP scenario consistent with limiting global warming to 1.5C (light red). Also shown is the Met Office forecast for 2025 (red).

The table below sets out decadal averages of the annual rise in CO2 concentrations at Mauna Loa. The first half of the 2020s has seen an average CO2 rise of 2.58ppm/year, which is 44-94% higher than it needs to be to track the IPCC 1.5C-compatible scenarios.

Decade Observed average CO2 rise (ppm/year)
1960s 0.86
1970s 1.22
1980s 1.58
1990s 1.55
2000s 1.91
2010s 2.41
2020s (2020-2024) 2.58

In fact, the annual rise of 3.58ppm/year between 2023 and 2024 at Mauna Loa was the fastest on record.

The global average, which has been monitored by satellite since 2003, also showed a large rise last year – and, at 2.9ppm/year, this was the second largest on record after 2015-16.

(While the rise at Mauna Loa mirrors the global rise over long periods, in the short term it can also be affected by localised effects, such as fires upwind or in the same hemisphere, before the CO2 disperses more evenly across the globe.)

Global CO2 emissions were also at a record high in 2024, but a further key factor was that natural land carbon “sinks” were substantially weaker, allowing more of the emitted CO2 to remain in the atmosphere.

At least some of this weakening of land carbon sinks was associated with the El Niño conditions in the first part of the year. El Niño events shift weather patterns around the globe, leading to hotter, drier conditions in many parts of the tropics. This means that vegetation grows less well and more carbon is released from decay in soils and from wildfires, leading to land ecosystems removing less carbon from the atmosphere than usual.

With the El Niño now subsided and conditions shifting more towards the opposite pattern of La Niña, natural land carbon sinks can be expected to recover again, at least to some extent.

As a result, in our Met Office forecast of the CO2 rise at Mauna Loa, we predict a slower rate of rise between 2024 and 2025 than between 2023 and 2024. The projected increase is 2.26ppm (with an uncertainty range of ±0.56ppm) – slightly slower than it would have been without the effects of La Niña.

However, even this is still too fast to stay on track with the IPCC 1.5C-compatible scenarios. This is highlighted in the chart below, which shows the annual change in CO2 levels at Mauna Loa since 1995 (blue lines) and how our forecast for 2025 (red point) exceeds a pathway consistent with 1.5C (grey plume).

Comparison of recent and forecast annual change in atmospheric CO2 concentration
Comparison of recent and forecast annual change in atmospheric CO2 concentration with an illustrative scenario limiting global warming to 1.5C. Light blue thin line: Annual change in CO2 concentration at the Mauna Loa observatory from observations. Mid-blue thin line: Annual increments in CO2 concentration at the Mauna Loa observatory reconstructed using statistical relationship between concentrations, emissions and the El Niño-Southern Oscillation (ENSO). Red dot with vertical error bars: the 2025 forecast increment. Dark blue thick line and dark blue dot: estimated increments without the influence of ENSO. Grey plume: simulated CO2 concentrations in the C1-IMP-SP scenario limiting global warming to 1.5C with >50% likelihood.

Faster rise than expected

The specific reasons for the very large increase in CO2 in 2024 are not yet completely clear, although weaker land carbon sinks appear to be implicated.

We had forecast the 2023-24 CO2 rise at Mauna Loa to be 2.84ppm (±0.54) – faster than the average of the previous decade due to the El Niño. We had also highlighted the possibility that it could be the fastest annual rise on record.

However, the actual CO2 rise of 3.58ppm was even faster than expected. This was above the upper limit of our uncertainty range, which should include the forecast value 95% of the time.

Although carbon emissions from fossil fuel burning and deforestation were also at a record high in 2024, this does not fully explain the shortfall in our forecast.

Our forecast method uses the global emissions from the previous year as one of the inputs. The emissions in 2024 were estimated to have been 11.3bn tonnes of carbon (GtC), slightly higher than the 2023 value of 11.1GtC used in our forecast.

This 0.2GtC difference is equivalent to about 0.09ppm of CO2 in the atmosphere. So, even if we had used the larger value in our forecast, the observed rise would still have been beyond our uncertainty range.

Therefore, the origin of the discrepancy must be related to natural carbon sinks, which must have been even weaker than the expected weakening that occurred as a result of the 2023-24 El Niño.

Weaker land carbon sinks

Scientists had already established that land carbon sinks were exceptionally weak in 2023, with very high temperatures worldwide playing a part in this.

2024 was then even hotter than 2023 – and indeed was the first calendar year where warming exceeded 1.5C above pre-industrial levels. It can be expected that the climatic conditions this warmer year once again led to weaker global land carbon sink.

Both North and South America saw high temperatures and exceptionally severe fires in 2024, including in regions not normally affected by El Niño such as Canada, and extending beyond the season of El Niño influence.

Global fire emissions were estimated as 1.6-2.2GtC over January-September 2024, 11-32% above the 2014-23 average for the same months.

Moreover, fire emissions in the northern hemisphere were 0.5-0.6 GtC per year, which was 26-44% above the average of 2014-23. Since Mauno Loa is in the northern hemisphere, this may explain why the local rise there was even larger than the global average.

A portion of these fire emissions may already be accounted for in the above estimate of land-use emissions, but it is not possible to quantify this. Nevertheless, widespread fire activity likely contributed to the large rise in atmospheric CO2 concentrations in 2024. Further analysis is needed to quantify the size of this contribution.

Climate change itself may have played a role in enhancing fire emissions. For example, human-caused warming made the “unprecedented” wildfires that spread across Brazil’s Pantanal wetlands in June 2024 between four and five times more likely.

Although land carbon sinks are generally increasing as a result of rising CO2, Earth system model projections have long indicated that ongoing global warming would reduce this effect, leading to a greater proportion of human-caused emissions remaining in the atmosphere.

Calculations suggest that this has already been occurring in recent years, so a key question is whether the last two years have seen an acceleration. If natural carbon sinks weaken more than already expected, this would further increase the difficulty of slowing the rise in atmospheric CO2 concentrations.

Alternatively, there are a number of historical years for which our CO2 forecast procedure gives almost as large departures between predictions and outcomes as for 2024. For example, 2003 saw a large rise at Mauna Loa despite not being an El Niño year, due to large fires in Siberia. It will therefore be important to see whether there is a higher-than-expected rise in CO2 in 2025, or whether the large exceedance in 2024 is a temporary phenomenon.

With global warming ongoing, extremely high temperatures will continue to occur more frequently and severely, so events such as those seen in 2023 and 2024 could play an ever more important role in the global carbon cycle.

The contribution of fires attributed to climate change is consistent with model simulations which suggest that global fire activity will already be weakening land carbon sinks. Further monitoring of the global carbon cycle will help to reveal whether this is indeed the case.

The post Met Office: Atmospheric CO2 rise now exceeding IPCC 1.5C pathways appeared first on Carbon Brief.

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Cropped 13 August 2025: Fossil-fuelled bird decline; ‘Deadly’ wildfires; Empty nature fund

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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

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

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Holding the line on climate: EPA

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A white man sits at a conference room style table, with papers in front of him, gesturing as he speaks. Three other people in business attire sit in the seats next to him.

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.

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Analysis: England’s most ethnically diverse areas are 15 times more likely to face extreme heat

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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.

Chart showing that people living in English neighbourhoods with lower carbon footprints are more likely to be exposed to extreme heat
Proportion of neighbourhoods in England with the highest heat hazard scores in each carbon footprint bracket. Each bar represents a group of English neighbourhoods, ranked by their per-capita emissions from 10% with the lowest carbon footprints (top bar) to the 10% with the highest (bottom bar). The bars in between each represent 20% of neighbourhoods. The “highest heat hazard scores” equate to the top 10% of total English neighbourhoods that are most likely to experience high temperatures during hot weather. Source: Carbon Brief analysis, 4 Earth Intelligence, CREDS.

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.

Chart showing neighbourhoods in England that are home to more minority-ethnic people are far more likely to face extreme heat
Proportion of neighbourhoods in England with the highest heat hazard scores in each decile of minority-ethnic population. Each bar represents 10% of English neighbourhoods, ranked by their proportion of minority-ethnic inhabitants, from the highest (top bar) to the lowest (bottom bar). The “highest heat hazard scores” equate to the top 10% of total English neighbourhoods that are most likely to experience high temperatures during hot weather. Source: Carbon Brief analysis, 4 Earth Intelligence, Office for National Statistics.

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.

Chart show more deprived areas in England are also more likely to experience extreme heat
Proportion of neighbourhoods in England with the highest heat hazard scores in each decile of deprivation. Each bar represents 10% of English neighbourhoods, ranked by their level of deprivation, from the highest (top bar) to the lowest (bottom bar). The “highest heat hazard scores” equate to the top 10% of total English neighbourhoods that are most likely to experience high temperatures during hot weather. Source: Carbon Brief analysis, 4 Earth Intelligence, UK government indices of deprivation for England.

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.

Infographic diagram showing higher temperatures in cities lead to the formation of an urban heat dome
Illustration of air flow in and around a heat dome, based on Yang et al (2024). Graphic: Ada Carpenter, Carbon Brief.

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%.

Chart: Carbon Brief analysed the 10% of English neighbourhoods with the highest heat hazard scores
Distribution of heat hazard scores across English neighbourhoods, as calculated by 4EI. The top two heat hazard scores are 5 – representing the 1% of neighbourhoods that are more prone to extreme heat than the remaining 99% – and 4, representing the 90th-99th percentile that are hotter than the remaining 90%. Source: 4 Earth Intelligence.

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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