An uptick in heat extremes, driven by human-caused climate change, has caused tropical bird populations to decline by up to 38% since the 1950s, according to a first-of-its-kind analysis.
The study combines ecological and climate attribution techniques to trace the fingerprint of fossil-fuelled climate change on declining wildlife populations.
It shows 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.
The findings could help to explain why tropical bird numbers have declined even in pristine rainforests, a phenomenon that previously mystified biologists, the scientists say.
‘Chance encounter’
Over the past few decades, an emerging field of science known as “climate attribution” has used a standardised set of techniques to trace the fingerprint of human-caused warming on different elements of the climate system, ranging from worsening extreme weather events to episodes of glacier melt.
The new research, published in Nature Ecology and Evolution, is the first to use climate attribution techniques to detect the fingerprint of climate change on declining wildlife populations.
The study came about following a “chance encounter” between lead author Dr Maximilian Kotz, a climate scientist at the Barcelona Supercomputing Center in Spain, and his co-authors, who are biodiversity experts at the University of Queensland in Australia, while Kotz was completing a research stay in Australia.
Kotz says to Carbon Brief:
“As far as we are aware, this is the first animal climate attribution study.”
The researchers decided to focus on birds, rather than other animal species, as they have the “best available data, covering a good range of different species and geographies”, he adds.
Heat extremes
The authors examine how an intensification of heat extremes could have impacted bird populations, while controlling for other factors known to affect wildlife, including average temperature increase and human pressures, such as land-use change.
Episodes of extreme heat are known to have an immediate and long-lasting impact on birds, Kotz says:
“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.”
Using statistical techniques, the scientists first analyse historical records to identify how bird populations have responded to fluctuations in climate, including heat extremes, over 1950-2020.
The team sourced global data on bird populations from the database that underlies the Living Planet Index, put together by the environmental charity WWF. They note it is the most comprehensive database available, but still has “clear geographic biases”, with global north regions better represented than those in the global south.
They use an attribution framework to estimate the extent to which human-caused warming influenced the changes in heat extremes observed in that time period, then calculate the impact of these climate-change-driven heat extremes on bird population changes from 1950-2020.
(The authors defined “heat extremes” as temperatures within the top 1% of daily temperatures over 1940-70, with data taken from ERA5, a global reanalysis dataset, which combines data from weather stations, satellites and model output.)
To understand how this would compare to a world without climate change, the researchers subtract this impact from the historical records.
Comparing their results to the counterfactual world without climate change allowed them to quantify how bird populations have changed as a result of human-driven increases in heat extremes.
Mapped
The research finds that human-driven heat extremes have had “strong negative impacts” on bird population numbers, with those residing at lower latitudes being the most affected.
The map below shows the percentage change in bird population abundance attributed to heat extremes over 1950-2018, when compared to a world without climate change.
On the map, dark red shows large decreases in population abundance, while light blue indicates small increases. (Abundance refers to the number of individual animals in a given population.)
The research finds that birds in the tropics have experienced the largest declines attributable to heat extremes.
It concludes that an uptick in heat extremes has caused tropical bird abundance levels to decline by 25-38% in the period 1950-2020, when compared to a world without warming.
The range in the size of that impact reflects the results of different models, which each use slightly different techniques to simulate changes to bird populations, Kotz says.
Tropical turmoil
In their paper, the authors note that their finding that tropical birds have experienced the most substantial declines are “consistent” with other studies indicating that “birds in these regions may be closer to the thermal limits at which impacts start to occur”.
They add that the findings are “particularly pertinent, given recent documentation of declining tropical bird populations, even in undisturbed habitats”.
One previous study found that in a “relatively undisturbed” part of the Amazon rainforest, bird abundance declined by more than 50% from 2003 to 2022. Similar results were found in a forest in Panama.
The authors of the new study say:
“The source of such declines have been noted as unknown, yet they are of a similar order of magnitude to our estimates of the impacts of intensified heat extremes.”
Their results suggest that “in tropical realms, climate change impacts on bird populations may already be comparable to land pressures that lead to habitat destruction and degradation”, the authors say.
This has “potential ramifications” for commonly proposed conservation strategies, such as increasing the amount of land in the the tropics that is protected for nature, they continue:
“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 tells Carbon Brief.
He references one project in Australia which is working to protect threatened wildlife following periods of extreme heat, drought and bushfires.
Informing forecasts
As well as shedding light on what could be behind the rapid decline of birds in the tropics, the findings also underscore the importance of examining changes in climate extremes, rather than just annual global temperature rise, says Prof Alex Pigot, a biodiversity scientist at University College London (UCL), who was not involved in the research. He tells Carbon Brief:
“Most of the models that have been used to make projections of risk to biodiversity under future climate change use long-term climate averages and so the results of this study suggest that our existing risk assessments could be missing these critical impacts of climate change.
“We urgently need to address this and 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 and feed this information back into our models to refine our future projections for biodiversity.”
Dr Peter Soroye, a biodiversity scientist at the Wildlife Conservation Society Canada, who was also not involved in the research, agrees:
“It’s not just that the climate is getting gradually warmer every year with climate change, it’s that climate change is also driving increasingly frequent and severe extreme temperature events that are putting wildlife at risk.
“As we more fully understand the importance of extremes, it seems increasingly important to consider them when we model or project changes in biodiversity over time.”
The post Fossil-fuelled heat has caused tropical birds to decline by ‘up to 38%’ since 1950s appeared first on Carbon Brief.
Fossil-fuelled heat has caused tropical birds to decline by ‘up to 38%’ since 1950s
As an extreme El Niño breaks marine temperature records, COP31 is set to boost the profile of the ocean’s role in solving climate change, but finance and clear conservation measures will be needed for it to move the needle, experts said.
The Turkish presidency has announced plans for an Antalya Ocean Declaration that recognises the centrality of the global ocean – the world’s largest carbon sink – in regulating the climate and minimising the now unavoidable overshoot of global temperatures above 1.5C over pre-industrial levels.
Meanwhile, as part of the formal UN negotiations, Australia has announced plans to land a cover decision in Antalya, which, according to veteran former US negotiator Sue Biniaz, would be the only section of the formal negotiations where the role of oceans could be included.
She added that an outcome at COP31 seems likely, given the initiative from both presidencies and a push from over 100 countries – including Brazil, the EU and the African Group of countries – calling for the UN negotiations to deliver a plan for implementing ocean measures.
Governments will arrive in Antalya with a “super El Niño” adding stress to marine ecosystems and expected to continue to intensify until December 2026, with parts of the Pacific averaging almost 30C (86F) – over 3C more than normal – in October, according to monthly EU sea temperature data.
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COP31 Briefing: What to expect from the Antalya climate summit?
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Nepal seeks stronger recognition of mountain issues in UN climate process
Flood-hit Nepal wants COP31 to adopt a new agenda item formalising work on mountains and climate change and boosting the response to rising risks
Needs for ocean conservation and funding
While elevating the ocean agenda is “critical”, it must lead to funding for ocean conservation and a clear plan for reaching the global target – set at UN biodiversity talks in 2022 – of protecting 30% of the global ocean by 2030, said Pradeep Singh, senior ocean governance expert at Oceano Azul Foundation.
The ocean is precisely where governments are farthest off track from meeting this target – informally known as the 30×30 goal. Even if countries meet all their nature conservation plans, only about 12% of the global ocean would be protected, the UN says.
“Acknowledgment of marine protected areas and the 30×30 target as climate infrastructures will certainly boost efforts and funding for science and management,” Singh told Climate Home News.
Shamini Selvaratnam, director of international climate and clean energy at Ocean Conservancy, said an ocean commitment that makes a difference in coastal communities “takes funding, local capacity and support that countries can actually access”.
An analysis by climate think tank Zero Carbon Analytics shows that investment in the blue economy – through activities like sustainable fisheries or cleaner shipping – is only at about 2% of the needs, which are estimated at $550 billion per year.
Following-through on commitments
Selvaratnam added that countries must also establish mechanisms to follow through on these measures, which currently only exists in the form of a non-binding dialogue that is not expected to produce any negotiated agreements.
She said that countries at COP31 must find ways for their ocean commitments to inform the next global stocktake, the UN’s five-yearly review of progress on climate action. Some countries – including African countries, Latin American nations, small island states and the European Union – have backed a process that culminates in the next global stocktake.
At climate negotiations, countries are not mandated to include ocean conservation measures in their climate plans. But a group of countries led by France and Brazil is pushing them to do so voluntarily through an initiative called Blue NDC Challenge. Seventeen countries have joined the initiative so far.
In its list of COP31 priorities, the EU has called for the “critical role” of oceans to be recognised, but falls short of calling for any specific actions to feature marine action more prominently in climate plans.
As part of their demands, ocean campaign groups have called for the establishment of an “Antalya Ocean Compact”, a platform where countries can coordinate efforts across different environmental treaties, including the UN climate, biodiversity and high seas negotiations.
Ultimately, Selvaratnam said a strong deal “must accelerate emissions cuts, clean energy, and a transition away from fossil fuels, including offshore oil and gas”.
Ilana Seid, chair of the AOSIS group of small island states and permanent representative of Palau to the UN, said during a press briefing last week that “meaningful progress” on emissions reduction is “the best way” to alleviate stress on the ocean.
The post ‘Blue COP31’ set to spotlight need for ocean protections amid record heat appeared first on Climate Home News.
‘Blue COP31’ set to spotlight need for ocean protections amid record heat
In the wake of its recent glacial flooding disaster, Nepal and the kingdom of Bhutan have proposed a new agenda item on mountains and climate change for the COP31 summit which opens on Monday in the Turkish city of Antalya.
In a submission addressed to the COP31 presidency and the head of the UN climate secretariat (UNFCCC), Nepal said the agenda item, entitled “1.5°C Warming in Mountains”, is an effort to strengthen the response of the international community to the climate risks facing the world’s mountain regions.
The item proposes that mountain issues should become a regular part of the formal UN climate change process, with a focus on scientific assessment of the risks associated with warming overshooting 1.5C, an annual high-level dialogue, a dedicated work programme and improved access to climate finance.
Maheshwar Dhakal, chief of the climate change management division of Nepal’s Ministry of Agriculture, Forests and Environment, told Climate Home News that Himalayan countries face similar problems such as collapsing glaciers and flooding from glacial lakes.
“We are trying to bring all Himalayan countries together under this agenda item,” he said.
COP31 Briefing: What to expect from the Antalya climate summit?
At this year’s UN General Assembly, Nepal’s Prime Minister Balendra Shah called for strong global action to ensure climate justice and proposed creating a Himalayan Climate Resilience Mechanism led by India, China and Nepal. It would share satellite data, monitor glacial slopes and lakes, strengthen early warning systems and coordinate cross-border disaster response.
Nepal has experienced significant infrastructure losses and human casualties from flooding every year since 2020. In late August, the collapse of a glacial slope on the border with Tibet caused a torrent of water and debris to course down the Bhote Koshi River, leaving more than 6,000 people dead or missing.
According to a government needs assessment, the disaster caused an estimated $2.7 billion in physical damage and economic losses, while around $4.8 billion will be required for recovery and reconstruction.
More research needed on threats
Although high mountain regions are known to be fragile ecosystems, especially as global warming accelerates glacier melt, the extent of their vulnerability is still not fully understood. When the devastating Bhote Koshi floods hit, it opened the eyes of the world to the risks.
Dhakal said the Bhote Koshi floods “have proved the impacts of climate change in the Himalayan region”, which were linked to rising temperatures by scientists with the World Weather Attribution group. “Therefore, Nepal wants scientific studies, research and political discussions on mountain climate risks to receive greater attention at international climate conferences,” he added.
Nepal has been making efforts on this front since 2009, when it held a cabinet meeting at Kalapatthar near Mount Everest. Since COP28 in Dubai, Nepal has organised high-level events and dialogues on mountain issues at COPs and is co-hosting one at COP31 with Bhutan, Pakistan, Kyrgyzstan and Tajikistan.
Editor’s Desk: Nepal’s disaster has laid bare the world’s adaptation accountability gap
Dhakal said the dialogues held so far have raised awareness, but mountain concerns must become part of the formal UN climate process to unlock climate finance and technical support that can bolster countries’ capacity to tackle climate threats.
If specific indicators and priorities are developed for mountain regions, vulnerable developing countries like Nepal would have better access to finance to help them adapt to the climate warming they have done very little to cause, he added.
More detailed data would enable them to prepare stronger project proposals for international climate funds, including the Green Climate Fund (GCF). In 2025, the GCF backed a project to protect livelihoods from climate-induced flooding in Nepal but it took seven years to get approval.
Sindhu Dhungana, an alternate board member at the GCF, said the problem is becoming more widespread and urgent for the Hindu Kush Himalaya region.
“The economies, cultures and almost everything in Himalayan countries depend on mountains,” he explained. “For us, climate change is mountain change… [it has] affected everything, including the economy and biodiversity.”
Destroyed development projects
Nepal wants the UN climate process to address mountain risks both before and after disasters. Countries need better research, technology, early warning systems and other adaptation measures to protect people and infrastructure. But even when countries take precautions, loss and damage is likely to occur and will require international support to address it.
Nepal has been provisionally allocated $21.6 million from the United Nations’ new Fund for Responding to Loss and Damage (FRLD) to help with the aftermath of the Bhote Koshi disaster, but this is just a fraction of needs and the money will come only months after it made an initial request.
Dhakal pointed to the damage caused by floods to infrastructure built with loans, such as the Melamchi Drinking Water Project, which received $312 million from the Asian Development Bank but was destroyed by a major flood in 2021, shortly after it began operating. The recent Bhote Koshi disaster wiped out a dozen hydropower facilities, as well as solar energy systems.
Nepal flood destruction shows “limits to adaptation”, scientists say
Nepal wants international discussions on what should happen when climate-related disasters destroy development projects built using credit, and how the loans should be treated afterwards.
“Climatic disasters wash out… projects, but the burden of loan is still paid by Nepal,” Dhakal said.
For now, it remains unclear whether the opening session of COP31 will consider or adopt the proposed agenda item on mountains and climate change, with consultations on how to respond still underway among governments and the COP31 co-presidencies.
“If countries agree to discuss the proposal and include it in the agenda, that would be another step forward,” Dhakal said. “Further discussions in the coming years could gradually give the mountain agenda a stronger shape.”
The post Nepal seeks stronger recognition of mountain issues in UN climate process appeared first on Climate Home News.
Nepal seeks stronger recognition of mountain issues in UN climate process
Some governments have backed using Brazil’s voluntary roadmaps on fossil fuels and deforestation to inform the next UN assessment of global climate action, a key process that concludes in 2028, the COP30 presidency told Climate Home News.
Brazil published the roadmaps on transitioning away from fossil fuels and on halting deforestation by 2030 this week, after failing to secure an agreement in Belém to make them part of formal negotiations. The documents set out a menu of policies countries could use to start acting on both issues straight away.
At their launch, Brazilian top climate officials argued the roadmaps could feed into the second stocktake negotiations. Through that process, due to start at this year’s COP, countries are meant to take stock of collective progress on climate action and decide on a plan to ramp up ambition in future policies.
In an interview with Climate Home News in London, COP30 president André Corrêa do Lago said that “some European governments” had signalled their support for the Brazil-led roadmaps to inform the global stocktake negotiations.
“I hope that there will be many other countries that may support this,” he said. “It’s not that you have to take the entire package, because who are we to come up with the solution? But some elements of the roadmaps may be useful.”