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. This is the last edition of Cropped for 2025. The newsletter will return on 14 January 2026.
Key developments
UN talks face headwinds
GLOBAL OUTLOOK: A major new report calling for joint action on climate change and biodiversity was published this month at the UN Environment Assembly talks in Nairobi, Kenya, the Associated Press reported. The newswire said that more than 300 scientists from 83 countries contributed to the latest UN Environment Programme (UNEP) global environment outlook report.
‘SHARP DIVISIONS’: However, for the first time ever, countries failed to agree on a “summary for policymakers” to be published alongside the outlook, according to Agence France-Presse. It said that “sharp divisions” prevented countries reaching consensus on the high-level political summary, with “major oil producers Saudi Arabia and the US oppos[ing] references to phasing out fossil fuels”. The newswire added that UNEP chief Inger Andersen called the lack of a summary “regrettable”, but said the “integrity of the report” remained.
NEW AGREEMENTS: Separate to the report, negotiators in Nairobi were also tasked with agreeing on 15 resolutions and two decisions on a wide range of environmental topics, from plastics to the impact of artificial intelligence, forcing them to “work throughout the day and into the night” towards the end of the summit, according to the Earth Negotiations Bulletin (ENB). In the end, countries adopted 11 resolutions, including on protecting coral reefs from climate change, the global management of wildfires and the preservation of glaciers, a second ENB report said.
TURKISH INFLUENCE: Climate Home News reported that Turkey, the country co-hosting the COP31 climate summit next year alongside Australia, “sought to weaken language on climate change in several draft resolutions” being discussed at the talks. The publication said that the nation, often working alongside Saudi Arabia, “pushed to dilute wording on the climate crisis, the science of melting glaciers and the role of young and Indigenous people”. A separate Climate Home News story said that countries agreed to a first-of-its-kind resolution on addressing the environmental effects of AI, but failed to include a reference to examining its “life cycle” impacts.
‘Deadly’ Asia floods
‘NOT NORMAL’: Climate change made the rainfall behind the “deadly” floods and landslides in parts of south Asia earlier this month more likely to occur and more intense, a World Weather Attribution study covered by the Hindustan Times found. Deforestation and rapid urbanisation also contributed to the extreme flooding that killed more than 1,600 people in several countries, including Sri Lanka, Malaysia and Thailand, the newspaper said. The Guardian noted that while monsoon rains often bring flooding, scientists said this level of intensity was “not normal”.
FOREST LOSS: Mongabay looked at how deforestation contributed to the “catastrophic” impacts from Cyclone Senyar, which caused floods and landslides in Sumatra, Indonesia. The outlet said that “decades of deforestation, mining, plantations and peat drainage left watersheds unable to absorb intense rainfall”. Indonesian environmental group WALHI told the Associated Press that deforestation “stripped away natural defences that once absorbed rainfall and stabilised soil”. Gus Irawan Pasaribu, a local government leader in Tapanuli, told Reuters: “If our forests were well-preserved…it would not have been this terrible.”
NATURE IMPACTS: A separate Mongabay article reported on the “extensive” damage caused by Cyclone Ditwah to Sri Lanka’s “biodiversity-rich” central highlands earlier this month. The outlet said that initial assessments have shown disastrous impacts of flooding and landslides in places such as the Knuckles mountain range, a “Unesco-listed biodiversity hotspot”. Meanwhile, the floods that hit Indonesia were an “extinction-level disturbance” for the Tapanuli orangutan – the world’s rarest great ape, scientists told the Guardian.
Spotlight
Building a bird sanctuary at a London reservoir
In this Spotlight, Carbon Brief visits a radical conservation project aiming to reverse a decline in water birds at a Victorian reservoir in north London.
“I’d recommend bringing wellies! It’s very muddy.”
Those were the instructions of Ben MacMillan, an ecologist at the Canal & River Trust, a charity responsible for looking after the UK’s waterways, including canals, reservoirs and towpaths.
On a damp and grey Tuesday morning, he guided Carbon Brief round the back of a playing fields car park in Hendon, north London, past a metal fence reading “no entry” and across ground covered by several inches of mud to the unlikely site of a radical new conservation effort.
The site is at a degraded wetlands on the northern edge of the Welsh Harp reservoir, a large human-made lake capable of holding 400 Olympic-sized swimming pools of water, first established by the Victorians in the 1830s.
In the 1950s, the reservoir was declared one of the UK’s “sites of special scientific interest”, due to its ability to host an unusually large number of species, including breeding waterbirds, such as silvery-grey common terns and elegant great-crested grebes.
Despite the designation, little was done to protect the site from various threats, including the spread of invasive species, increasing urbanisation and pollution from major roads. The reservoir is bordered on one side by the M1, the main motorway from London to northern England, and by the North Circular, part of central London’s busy ring-road, on another.
In the 1980s, a conservation project led by ecologist Leo Batten transformed the site to create new refuges for breeding birds.
However, for the past 40 years, the reservoir has fallen into “mismanagement”, according to MacMillan – with devastating consequences for its wildlife.
In 2022, just two tern chicks were successfully fledged at the reservoir, compared to 44 in 2000, MacMillan said. Great-crested grebe nests have also dropped from 55 in 1987 to 27 in 2022.
Redesigning the landscape
The dramatic decline has spurred the start of a new £400m restoration project, called “wings on water”, which began in October 2025 and will continue for the next three years.
Headed by MacMillan, the project is making radical changes to the landscape of the site in order to create new habitats and breeding spots for its water birds.
MacMillan has contracted the services of restoration specialists Ebsford Environmental, who have used diggers to create a network of channels across the site.
These channels have uncovered a series of islands that can offer birds a safe place to breed, away from predators such as urban foxes and mink, MacMillan said.
As well as dredging the landscape, MacMillan also plans to introduce new micro-ecosystems, such as wildflower meadows, that will eventually form a “patchwork” capable of supporting a wide range of species.
“It’s all about creating a diversity of habitat,” he said. “It might take five or 10 years to develop, but eventually we’ll end up with an amazing complex mosaic of habitats.”
While MacMillan is “very happy” with the progress being made, the project has some issues to contend with.
One of the recently dug channels is contaminated by toxic silt, poisoned by the runoff of petrol from the nearby major roads. If the petrol seeps out of the silt, it could coat the feathers of birds, negatively affecting their health, MacMillan said.
Ninja turtle legacy
The site is also home to a number of invasive species, each with their own impacts.
One animal causing a particular nuisance are red-eared terrapins, a type of omnivorous shelled reptile, similar in appearance to a turtle, that are native to the US.
“They link back to the 1990s Teenage Mutant Ninja Turtle craze,” MacMillan explained. “People bought loads of them. Then they thought: ‘Oh, these are getting a bit big now’ – and decided to release them in their local park.”
Terrapins have a life span of around 40 years, meaning many released on a whim 30 years ago have now established themselves in waterway habitats across the UK.
While terrapins feed on plants, they have also been seen taking chicks and eggs from nesting birds, MacMillan said:
“In an ideal world, we would move them on. But in practice, it’s very difficult to actually catch them.”
As well as restoring the site for the good of birds, the project also aims to improve access to nature for the local community.
The team plans to install a new boardwalk and viewing platform for the public, which they aim to open next year.
“It should provide a really nice space for people to take a walk in a green space, while being able to spot some breeding birds, in a very urbanised area,” MacMillan said.
News and views
NATURE CASH: The ‘Cali Fund’ – which could generate billions of dollars each year for conservation – recently received its first donation of just $1,000, Carbon Brief reported. On 19 November, nine months after the fund launched, UK start-up TierraViva AI put forward the contribution. The company’s chief executive told Carbon Brief that this was an “ice-breaker” aimed to encourage others to pay in. One expert described the contribution as a good “first step”, but said it is now “time for larger actors to step forward”. Large companies in sectors such as pharmaceutical, cosmetic, biotechnology, agribusiness and technology could contribute to the fund.
FARMING LOSSES: UK crop farmers lost more than £800m in 2025 due to poor harvests and “record heat and drought”, the Guardian reported, based on analysis from the Energy and Climate Intelligence Unit (ECIU). Farmers recorded one of the worst harvests on record this year, with production of wheat, oats, spring and winter barley and oilseed rape dropping 20% below the 10-year average. Three of the five worst harvests have occurred since 2020, the newspaper added, quoting the ECIU’s Tom Lancaster: “The evidence suggests that climate impacts are what’s actually driving issues of profitability.” Meanwhile, BBC News reported that the UK government “roll[ed] back” certain nature protection requirements for housing developers in England.
CLIMATE FINANCE: Biodiversity, conservation and anti-desertification programmes in Africa have struggled to fill a “funding vacuum” since the US froze its development aid earlier this year, according to Mongabay. Experts and observers told the outlet they are “increasingly concerned” about the funding gap that “neither Europe nor billionaire philanthropists seem ready to fill”. Amhed Moustapha Mfokeu, a Cameroonian expert in climate finance, told Mongabay that the closure of the US Agency for International Development (USAID) “created a significant gap in funding for climate-related projects”.
SAVING SOILS: Around 70% of countries do not prioritise soil restoration in their national climate plans, a new report covered by EFEVerde found. The report, from the International Union for the Conservation of Nature’s world commission on environmental law and other groups, said that healthier soils can absorb more carbon and help to limit global warming, the outlet noted. Praveena Sridhar from the Save Soil movement wrote in Earth.org that the recent COP30 climate talks in Brazil “regarded [soils] as a sub-component of the agricultural machine, instead of the foundation to agriculture and many other components of terrestrial life”.
TRADE DEAL: The European parliament voted in favour of including measures to “protect European farmers” in a potential trade deal with South American countries, Bloomberg reported. The outlet said the EU is “rushing” this week to finalise the Mercosur deal, which has been negotiated over the past 25 years and aims to boost trade between the EU and Argentina, Brazil, Uruguay and Paraguay. Reuters reported that France and Italy want to delay the vote, with France trying to “form a blocking minority” against the agreement.
XMAS CHEER: Christmas tree farmers in Canada are adapting to climate change impacts such as warmer weather, CBC News reported. Michael Cormack, who owns a tree farm near Toronto, told the outlet: “This year in July, we were averaging over 29C. So we had trees from two to three years ago that just died…Four years ago, we had a tornado here that wiped out a bunch of our stuff.” The outlet also addressed the age-old question of whether a real or artificial christmas tree is more “eco-friendly”, with one tree researcher saying that a real tree bought from a “local farmer” tends to be a lower-emission choice, or re-using an artificial tree for a long time.
Watch, read, listen
KOLAHOI GLACIER: A retreating glacier in Kashmir is “transforming landscapes and communities”, the Guardian said.
FISHY: DeSmog investigated accusations that the world’s largest salmon producer has wielded a “charm offensive” in the Scottish Highlands to distract from its “noisy” and “polluting” fish farms.
LIVING UNDER THREAT: The Associated Press reported on the “steep risks” environmental activists face in Colombia – the “deadliest country in the world” for environmental defenders.
BAMBOO BARRIER: Rivercane – a species of bamboo – could help protect the southern US from future floods, Grist reported.
New science
- Hard coral cover in Caribbean reefs has reduced by almost half since 1980 | Global Coral Reef Monitoring Network and International Coral Reef Initiative
- Three decades of Amazon forest data shows “higher tree mortality during intense droughts” | Nature
- Vertebrate species could face unsuitable conditions across 10-52% of their range by 2100 due to climate and land-use changes | Global Change Biology
In the diary
- 15-19 December: 70th meeting of the Global Environment Facility council | Virtual
Cropped is researched and written by Dr Giuliana Viglione, Aruna Chandrasekhar, Daisy Dunne, Orla Dwyer and Yanine Quiroz. Ayesha Tandon also contributed to this issue. Please send tips and feedback to cropped@carbonbrief.org
The post Cropped 17 December 2025: ‘Deadly’ Asia floods; Boosting London’s water birds; UN headwinds appeared first on Carbon Brief.
Cropped 17 December 2025: ‘Deadly’ Asia floods; Boosting London’s water birds; UN headwinds
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’: