Welcome to Carbon Brief’s DeBriefed.
An essential guide to the week’s key developments relating to climate change.
This week
EU easing up
HITTING THE BREAKS: The EU “walked back” its target to ban the sale of petrol and diesel cars by 2035, “permitting some new combustion engine cars”, reported Agence-France Presse. Under the original plan, the bloc would have had to cut emissions entirely by 2035 on new vehicles, but will now only have to cut emissions by 90% by that date, compared to 2021 levels. However, according to the Financial Times, some car manufacturers have “soured” on the reversal.
ADJUSTING CBAM: Meanwhile, the Financial Times reported that the EU is making plans to “close loopholes” in the bloc’s carbon border adjustment mechanism (CBAM) before it goes into effect in January. CBAM is set to be the world’s first carbon border tax and has drawn ire from key trading partners. The EU has also finalised a plan to delay its anti-deforestation legislation for another year, according to Carbon Pulse.
Around the world
- NCAR NO MORE: The Trump administration is moving to “dismantle” the National Center for Atmospheric Research in Colorado, said USA Today, describing it as “one of the world’s leading climate research labs”.
- DEADLY FLOODS: The deadliest flash flooding in Morocco in a decade killed “at least” 37 people, while residents accused the government of “ignoring known flood risks and failing to maintain basic infrastructure”, reported Radio France Internationale.
- FAILING GRADE: The past year was the “warmest and wettest” ever recorded in the Arctic, with implications for “global sea level rise, weather patterns and commercial fisheries”, according to the US National Oceanic and Atmospheric Administration’s 2025 Arctic report card, covered by NPR.
- POWER TO THE PEOPLE: Reuters reported that Kenya signed a $311m agreement with an African infrastructure fund and India’s Power Grid Corporation for the “construction of two high-voltage electricity transmission lines” that could provide power for millions of people.
- BP’S NEW EXEC: BP has appointed Woodside Energy Group’s Meg O’Neill as its new chief executive amid a “renewed push to…double down on oil and gas after retreating from an ambitious renewables strategy”, said Reuters.
29
The number of consecutive years in which the Greenland ice sheet has experienced “continuous annual ice loss”, according to a Carbon Brief guest post.
Latest climate research
- Up to 4,000 glaciers could “disappear” per year during “peak glacier extinction”, projected to occur sometime between 2041 and 2055 | Nature Climate Change
- The rate of sea level rise across the coastal US doubled over the past century | AGU Advances
- Repression and criminalisation of climate and environmentally focused protests are a “global phenomena”, according to an analysis of 14 countries | Environmental Politics
(For more, see Carbon Brief’s in-depth daily summaries of the top climate news stories on Monday, Tuesday, Wednesday, Thursday and Friday.)
Captured
The latest coal market report from the International Energy Agency said that global coal use will reach record levels in 2025, but will decline by the end of the decade. Carbon Brief analysis of the report found that projected coal use in China for 2027 has been revised downwards by 127m tonnes, compared to the projection from the 2024 report – “more than cancelling out the effects of the Trump administration’s coal-friendly policies in the US”.
Spotlight
What climate scientists are curious about
This week, Carbon Brief spoke to climate scientists attending the annual meeting of the American Geophysical Union in New Orleans, Louisiana, about the most interesting research papers they read this year.
Their answers have been lightly edited for length and clarity.
Dr Christopher Callahan, assistant professor at Indiana University Bloomington
The most interesting research paper I read was a simple thought experiment asking when we would have known humans were changing the climate if we had always had perfect observations. The authors show that we could have detected a human influence on the climate as early as the 1880s, since we have a strong physical understanding of how those changes should look. This paper both highlights that we have been discernibly changing the climate for centuries and emphasises the importance of the modern climate observing network – a network that is currently threatened by budget cuts and staff shortages.
Prof Lucy Hutyra, distinguished professor at Boston University
The most interesting paper I read was in Nature Climate Change, where the researchers looked at how much mortality was associated with cold weather versus hot weather events and found that many more people died during cold weather events. Then, they estimated how much of a protective factor in the urban heat island is on those winter deaths and suggested that the winter benefits exceed the summer risks of mitigating extreme heat, so perhaps we shouldn’t mitigate extreme heat in cities.
This paper got me in a tizzy…It spurred an exciting new line of research. We’ll be publishing a response to this paper in 2026. I’m not sure their conclusion was correct, but it raised really excellent questions.
Dr Kristina Dahl, vice president for science at Climate Central
This year was when we saw source attribution studies, such as Chris Callahan‘s, really start to break through and be able to connect the emissions of specific emitters…to the impact of those emissions through heat or some other sort of damage function. [This] is really game-changing.
What [Callahan’s] paper showed is that the emissions of individual companies have an impact on extreme heat, which then has an impact on the GDP of the countries experiencing that extreme heat. And so, for the first time, you can really say: “Company X caused this condition which then led to this economic damage.”
Dr Antonia Hadjimichael, assistant professor at Pennsylvania State University
It was about interdisciplinary work – not that anything in it is ground-shakingly new, but it was a good conversation around interdisciplinary teams and what makes them work and what doesn’t make them work. And what I really liked about it is that they really emphasise the role of a connector – the scientist that navigates this space in between and makes sure that the things kind of glue together…The reason I really like this paper is that we don’t value those scientists in academia, in traditional metrics that we have.
Dr Santiago Botía, researcher at Max Planck Institute for Biogeochemistry
The most interesting paper I’ve read this year was about how soil fertility and water table depth control the response to drought in the Amazon. They found very nicely how the proximity to soil water controls the anomalies in gross primary productivity in the Amazon. And, with that methodology, they could explain the response of recent droughts and the “greening” of the forest during drought, which is kind of a counterintuitive [phenomenon], but it was very interesting.
Dr Gregory Johnson, affiliate professor at the University of Washington
This article explores the response of a fairly coarse spatial resolution climate model…to a scenario in which atmospheric CO2 is increased at 1% a year to doubling and then CO2 is more gradually removed from the atmosphere…[It finds] a large release of heat from the Southern Ocean, with substantial regional – and even global – climate impacts. I find this work interesting because it reminds us of the important – and potentially nonlinear – roles that changing ocean circulation and water properties play in modulating our climate.
Cecilia Keating also contributed to this spotlight.
Watch, read, listen
METHANE MATTERS: In the Guardian, Barbados prime minister Mia Mottley wrote that the world must “urgently target methane” to avoid the worst impacts of climate change.
CLIMATE WRAPPED: Grist summarised the major stories for Earth’s climate in 2025 – “the good, the bad and the ugly”.
COASTING: On the Coastal Call podcast, a biogeochemist spoke about “coastal change and community resilience” in the eastern US’s Long Island Sound.
Coming up
- 27 December: Cote D’Ivoire parliamentary elections
- 28 December: Central African Republic presidential and parliamentary elections
- 28 December: Guinean presidential election
Pick of the jobs
- BirdLife International, forest programme administrator | Salary: £28,000-£30,000. Location: Cambridge, UK
- World Resources Institute, power-sector transition senior manager | Salary: $116,000-$139,000. Location: Washington DC
- Fauna & Flora, operations lead for Liberia | Salary: $61,910. Location: Monrovia, Liberia
DeBriefed is edited by Daisy Dunne. Please send any tips or feedback to debriefed@carbonbrief.org.
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The post DeBriefed 19 December 2025: EU’s petrol car U-turn; Trump to axe ‘leading’ research lab; What climate scientists are reading appeared first on Carbon Brief.
Drought and heatwaves occurring together – known as “compound” events – have “surged” across the world since the early 2000s, a new study shows.
Compound drought and heat events (CDHEs) can have devastating effects, creating the ideal conditions for intense wildfires, such as Australia’s “Black Summer” of 2019-20 where bushfires burned 24m hectares and killed 33 people.
The research, published in Science Advances, finds that the increase in CDHEs is predominantly being driven by events that start with a heatwave.
The global area affected by such “heatwave-led” compound events has more than doubled between 1980-2001 and 2002-23, the study says.
The rapid increase in these events over the last 23 years cannot be explained solely by global warming, the authors note.
Since the late 1990s, feedbacks between the land and the atmosphere have become stronger, making heatwaves more likely to trigger drought conditions, they explain.
One of the study authors tells Carbon Brief that societies must pay greater attention to compound events, which can “cause severe impacts on ecosystems, agriculture and society”.
Compound events
CDHEs are extreme weather events where drought and heatwave conditions occur simultaneously – or shortly after each other – in the same region.
These events are often triggered by large-scale weather patterns, such as “blocking” highs, which can produce “prolonged” hot and dry conditions, according to the study.
Prof Sang-Wook Yeh is one of the study authors and a professor at the Ewha Womans University in South Korea. He tells Carbon Brief:
“When heatwaves and droughts occur together, the two hazards reinforce each other through land-atmosphere interactions. This amplifies surface heating and soil moisture deficits, making compound events more intense and damaging than single hazards.”
CDHEs can begin with either a heatwave or a drought.
The sequence of these extremes is important, the study says, as they have different drivers and impacts.
For example, in a CDHE where the heatwave was the precursor, increased direct sunshine causes more moisture loss from soils and plants, leading to a drought.
Conversely, in an event where the drought was the precursor, the lack of soil moisture means that less of the sun’s energy goes into evaporation and more goes into warming the Earth’s surface. This produces favourable conditions for heatwaves.
The study shows that the majority of CDHEs globally start out as a drought.
In recent years, there has been increasing focus on these events due to the devastating impact they have on agriculture, ecosystems and public health.
In Russia in the summer of 2010, a compound drought-heatwave event – and the associated wildfires – caused the death of nearly 55,000 people, the study notes.
The record-breaking Pacific north-west “heat dome” in 2021 triggered extreme drought conditions that caused “significant declines” in wheat yields, as well as in barley, canola and fruit production in British Columbia and Alberta, Canada, says the study.
Increasing events
To assess how CDHEs are changing, the researchers use daily reanalysis data to identify droughts and heatwaves events. (Reanalysis data combines past observations with climate models to create a historical climate record.) Then, using an algorithm, they analyse how these events overlap in both time and space.
The study covers the period from 1980 to 2023 and the world’s land surface, excluding polar regions where CDHEs are rare.
The research finds that the area of land affected by CDHEs has “increased substantially” since the early 2000s.
Heatwave-led events have been the main contributor to this increase, the study says, with their spatial extent rising 110% between 1980-2001 and 2002-23, compared to a 59% increase for drought-led events.
The map below shows the global distribution of CDHEs over 1980-2023. The charts show the percentage of the land surface affected by a heatwave-led CDHE (red) or a drought-led CDHE (yellow) in a given year (left) and relative increase in each CDHE type (right).
The study finds that CDHEs have occurred most frequently in northern South America, the southern US, eastern Europe, central Africa and south Asia.
Threshold passed
The authors explain that the increase in heatwave-led CDHEs is related to rising global temperatures, but that this does not tell the whole story.
In the earlier 22-year period of 1980-2001, the study finds that the spatial extent of heatwave-led CDHEs rises by 1.6% per 1C of global temperature rise. For the more-recent period of 2022-23, this increases “nearly eightfold” to 13.1%.
The change suggests that the rapid increase in the heatwave-led CDHEs occurred after the global average temperature “surpasse[d] a certain temperature threshold”, the paper says.
This threshold is an absolute global average temperature of 14.3C, the authors estimate (based on an 11-year average), which the world passed around the year 2000.
Investigating the recent surge in heatwave-leading CDHEs further, the researchers find a “regime shift” in land-atmosphere dynamics “toward a persistently intensified state after the late 1990s”.
In other words, the way that drier soils drive higher surface temperatures, and vice versa, is becoming stronger, resulting in more heatwave-led compound events.
Daily data
The research has some advantages over other previous studies, Yeh says. For instance, the new work uses daily estimations of CDHEs, compared to monthly data used in past research. This is “important for capturing the detailed occurrence” of these events, says Yeh.
He adds that another advantage of their study is that it distinguishes the sequence of droughts and heatwaves, which allows them to “better understand the differences” in the characteristics of CDHEs.
Dr Meryem Tanarhte is a climate scientist at the University Hassan II in Morocco, and Dr Ruth Cerezo Mota is a climatologist and a researcher at the National Autonomous University of Mexico. Both scientists, who were not involved in the study, agree that the daily estimations give a clearer picture of how CDHEs are changing.
Cerezo-Mota adds that another major contribution of the study is its global focus. She tells Carbon Brief that in some regions, such as Mexico and Africa, there is a lack of studies on CDHEs:
“Not because the events do not occur, but perhaps because [these regions] do not have all the data or the expertise to do so.”
However, she notes that the reanalysis data used by the study does have limitations with how it represents rainfall in some parts of the world.
Compound impacts
The study notes that if CDHEs continue to intensify – particularly events where heatwaves are the precursors – they could drive declining crop productivity, increased wildfire frequency and severe public health crises.
These impacts could be “much more rapid and severe as global warming continues”, Yeh tells Carbon Brief.
Tanarhte notes that these events can be forecasted up to 10 days ahead in many regions. Furthermore, she says, the strongest impacts can be prevented “through preparedness and adaptation”, including through “water management for agriculture, heatwave mitigation measures and wildfire mitigation”.
The study recommends reassessing current risk management strategies for these compound events. It also suggests incorporating the sequences of drought and heatwaves into compound event analysis frameworks “to enhance climate risk management”.
Cerezo-Mota says that it is clear that the world needs to be prepared for the increased occurrence of these events. She tells Carbon Brief:
“These [risk assessments and strategies] need to be carried out at the local level to understand the complexities of each region.”
The post Heatwaves driving recent ‘surge’ in compound drought and heat extremes appeared first on Carbon Brief.
Heatwaves driving recent ‘surge’ in compound drought and heat extremes
Greenhouse Gases
DeBriefed 6 March 2026: Iran energy crisis | China climate plan | Bristol’s ‘pioneering’ wind turbine
Welcome to Carbon Brief’s DeBriefed.
An essential guide to the week’s key developments relating to climate change.
This week
Energy crisis
ENERGY SPIKE: US-Israeli attacks on Iran and subsequent counterattacks across the Middle East have sent energy prices “soaring”, according to Reuters. The newswire reported that the region “accounts for just under a third of global oil production and almost a fifth of gas”. The Guardian noted that shipping traffic through the strait of Hormuz, which normally ferries 20% of the world’s oil, “all but ground to a halt”. The Financial Times reported that attacks by Iran on Middle East energy facilities – notably in Qatar – triggered the “biggest rise in gas prices since Russia’s full-scale invasion of Ukraine”.
‘RISK’ AND ‘BENEFITS’: Bloomberg reported on increases in diesel prices in Europe and the US, speculating that rising fuel costs could be “a risk for president Donald Trump”. US gas producers are “poised to benefit from the big disruption in global supply”, according to CNBC. Indian government sources told the Economic Times that Russia is prepared to “fulfil India’s energy demands”. China Daily quoted experts who said “China’s energy security remains fundamentally unshaken”, thanks to “emergency stockpiles and a wide array of import channels”.
‘ESSENTIAL’ RENEWABLES: Energy analysts said governments should cut their fossil-fuel reliance by investing in renewables, “rather than just seeking non-Gulf oil and gas suppliers”, reported Climate Home News. This message was echoed by UK business secretary Peter Kyle, who said “doubling down on renewables” was “essential” amid “regional instability”, according to the Daily Telegraph.
China’s climate plan
PEAK COAL?: China has set out its next “five-year plan” at the annual “two sessions” meeting of the National People’s Congress, including its climate strategy out to 2030, according to the Hong Kong-based South China Morning Post. The plan called for China to cut its carbon emissions per unit of gross domestic product (GDP) by 17% from 2026 to 2030, which “may allow for continued increase in emissions given the rate of GDP growth”, reported Reuters. The newswire added that the plan also had targets to reach peak coal in the next five years and replace 30m tonnes per year of coal with renewables.
ACTIVE YET PRUDENT: Bloomberg described the new plan as “cautious”, stating that it “frustrat[es] hopes for tighter policy that would drive the nation to peak carbon emissions well before president Xi Jinping’s 2030 deadline”. Carbon Brief has just published an in-depth analysis of the plan. China Daily reported that the strategy “highlights measures to promote the climate targets of peaking carbon dioxide emissions before 2030”, which China said it would work towards “actively yet prudently”.
Around the world
- EU RULES: The European Commission has proposed new “made in Europe” rules to support domestic low-carbon industries, “against fierce competition from China”, reported Agence France-Presse. Carbon Brief examined what it means for climate efforts.
- RECORD HEAT: The US