
A decade after the Paris Agreement took effect, climate-related heat, drought, floods, disease and dirty air are killing millions. The authors of a major annual report want the World Health Organization (WHO) to classify the crisis as a health emergency.
Climate change has become a global health emergency that needs a new WHO instrument to coordinate the global response, the Lancet Countdown on health and climate change said on Wednesday, in a new report that finds a warming world’s toll on health is rapidly expanding.
Heat caused by human-driven warming killed nearly three million people between 2016 and 2023; droughts and extreme rainfall spread faster, conditions for dengue and Vibrio bacteria reached new highs, and air pollution from burning fossil fuels is killing 2.78 million people a year, according to the Countdown’s 10th annual report, published in The Lancet.
“Because of the rapidly growing threats over the past decade, climate change has become a global health emergency,” the report asserts.
“Addressing it requires urgent course-correction to deliver coordinated and evidence-based action across borders to protect health and survival.”
Huge fossil fuel subsidies continue
As heatwaves turn to “heatstorms“, scorching forests, oceans and pavements around the globe, governments poured a net $6.2 trillion into direct fossil fuel subsidies from 2016 to 2024, the report found.
In 2024, 10 countries spent more propping up oil, gas and coal than on their health systems. Counting the unpaid costs of pollution and climate damage, the IMF puts total fossil fuel subsidies at about $7.4 trillion in 2024 alone, $6.7 trillion of it indirect – nearly 25 times the $300 billion a year that wealthy nations agreed in 2024 to deliver to developing countries for climate action by 2035.
The authors want WHO to develop a new instrument that formally recognises climate change as a global health emergency. Until one exists, they want existing tools, including the International Health Regulations (IHR), to be used to grade and respond to climate-driven health crises.

The WHO’s highest-level alarm, a public health emergency of international concern (PHEIC), has been used declared for COVID-19 and Ebola. However, it and other existing WHO instruments are designed for short outbreaks, not crises like climate change that run for decades.
“The problem currently with the public health emergency of international concern … is that it’s very tailored to short-lived emergencies and especially to emergencies that can cross borders like infectious diseases,” Marina Romanello, executive director of the Lancet Countdown, based at University College London, told a media briefing.
The Countdown wants an emergency response “that is fit for purpose, not only for emergencies like infectious diseases but also for catastrophes like those caused by climate change … so that we’re not responding to emergency after emergency”, Romanello added.
“A decade after the Paris Agreement, our findings are unambiguous: the health harms of climate change are growing faster than the world’s response to them, and in many cases even accelerating,” said Romanello.
Absence of political will
“What’s missing is not evidence, but the political will to act on it,” said Helen Clark, a former Prime Minister of New Zealand, who chairs the Countdown’s board. “Governments must double down on their climate action commitments and rebuild momentum for international co-operation.”
The findings land as the UN biodiversity summit, COP17, enters its final days in Yerevan, Armenia, with a first global stocktake of nature restoration by UN agencies due on Thursday. In two weeks, governments meet in Antalya, Türkiye, for the annual UN climate summit, COP31.
Last week, the UN Environment Programme found that the chance to hold warming to 1.5°C higher than pre-industrial temperatures without significant overshoot has passed. Current policies put the world on track for about a 2.8°C increase. Keeping the overshoot to 1.8°C in the coming decades would require emissions to nearly halve within 10 years.
The Countdown’s targets for the coming decade include an immediate ban on new fossil fuel exploration, an end to coal power by 2035, health early warning systems in every country by the end of 2027, a global climate and health data commons, and grant-based finance to enable countries to adapt to climate without taking on more debt.
Meeting those targets, the authors concluded, is “no longer just the greatest public health opportunity of the century”. It “may be the only hope for a safe future.”
“The evidence is undeniable,” said WHO Director-General Tedros Adhanom Ghebreyesus in a media release. “Climate change is one of the greatest threats to health facing humanity.”
Deadlier heat

Heat was linked to a record 710,000 deaths in 2023, and almost three-quarters (71.5%) were caused by climate change – the first time the Countdown has attributed heat deaths directly to human-driven warming.
Between 2016 and 2023, heat was linked to an average of 540,800 deaths a year, up 36% on the decade before. Climate change caused 68.4% of them, up from 55% in the decade before the Paris Agreement took effect.
As global warming hurtles towards the 1.5°C target set by the Paris Agreement, the climate-driven toll on health has grown by about 15,600 deaths each year on average. Newborns, pregnant women and older people bear the brunt, the report says. Earlier this month, UN climate chief Simon Stiell described heat’s threat to mothers and newborns as “a new fault line in the global climate crisis”.
“Heat-related mortality is just the tip of the iceberg,” Romanello told reporters ahead of the launch. “We know that behind every heat-related death, there’s a huge burden of disease, a huge increase in pressure on our health systems and healthcare.”
Heat erased 573 billion potential work hours in 2025 and $1.07 trillion in income, the third straight year above $1 trillion, according to the Countdown. Countries ranked lowest on the UN’s Human Development Index (HDI), which combines measures of health, education and income, lost the equivalent of 5% of their economic output, against 0.5% in the highest-ranked countries, with farm work accounting for 78% of their losses.
Meanwhile, the share of the world’s land in extreme drought grew eight times faster since 2016 than in the decade before, the report found, while the area hit by very extreme rainfall grew 57% faster.
Heatwaves and droughts pushed 127.9 million more people into moderate or severe food insecurity in 2024 than if their frequency had stayed at 1981–2010 levels.
Unhealthy diets contributed to 10.5 million deaths in 2023, up from 9.5 million in 2016, with red and processed meat and dairy linked to 1.6 million of them.
“In Southeast Asia, we’re seeing lost productivity due to heat being the equivalent of 3.9% of their GDP,” said Ollie Jay of the University of Sydney, who co-chairs the Countdown’s working group on health hazards.
“In an era where we’re so obsessed and preoccupied with growing the economy, this is a clear impact of climate change that is having a direct impact on the economic output of particular countries.”

Diseases on the move
Higher temperatures have also expanded the reach of diseases. For example, dengue cases hit a record 14.4 million in 2024 as the climate for its transmission by the Aedes aegypti mosquito, rose 125% faster than in the decade before.
Warming seas are spreading Vibrio bacteria too. Estimated cases of vibriosis, an infection picked up from warm coastal water and seafood, reached a record 738,000 in 2025, and have climbed by about 24,700 a year since 2016, up from 3,600 a year in the decade before.
Malaria and West Nile virus are also moving into new places. In Africa’s highlands, the climate suitability for the deadliest malaria parasite, P. falciparum, rose almost 13%, while the suitability for West Nile virus climbed 12% in Europe. Some tropical areas are now too hot for both, but more suitable for dengue, the report said.

Health systems left exposed
By 2025, 71% of WHO member states still had no plan to adapt their health systems to climate change, and 76% had not assessed their vulnerability since 2020, the report found.
Only 34.6% of the lowest-ranked countries on the HDI reported a strong ability to detect, prepare for and respond to health emergencies in 2025, in comparison to 80.6% of the highest-ranked countries, according to their own reports to WHO.
That capacity matters more as climate change makes such emergencies more frequent and severe, the report said.
Where climate-informed health early warning systems exist, now in 75 countries, the number of people affected by storms and floods is rising more slowly.
Developing countries have costed their health adaptation needs at $3.3 billion a year. However, donors committed $1.1 billion in 2024.
“We’re not nearly providing enough finance to support countries in a just transition to support adaptation and to protect the health of people in every country,” said Romanello.
Aid from the 17 largest donors, which pays for health, development and humanitarian work in low- and middle-income countries, is projected to fall by more than $50 billion (about 25%) between 2023 and 2026, led by the withdrawal by the United States. Several donors have tied the cuts to higher defence spending, the report found.
“In the context of climate change, where adaptation finance is already described as ‘grossly insufficient’ relative to needs, further reductions risk widening the gap between rising risks and available support,” the report said, “leaving people increasingly unprotected amid rising climate hazards.”
That gap will shape the fight over health finance at COP31 in Antalya.
Meanwhile, the share of countries linking climate and health in their speeches at the annual General Debate of the UN General Assembly fell from 65.9% in 2021 to 26.3% in 2025. Climate plans from the most developed countries are consistently the least likely to mention health, the report found.
“Climate change, and particularly climate change and health as an issue, is being crowded out by the fact that we’ve got greater global instability,” said Niheer Dasandi, a professor at the University of Birmingham who leads the Countdown’s work on political engagement.
“As conflicts increase, as tensions rise, we see much more of that international attention diverted towards those issues.”
The tightening grip of fossil fuels

Air pollution from burning fossil fuels killed 2.78 million people in 2023, about the same toll as in 2016. Deaths fell in 75 of the 140 countries assessed, led by China, saving 323,000 lives a year, but rising deaths elsewhere cancelled out the gain.
In countries in the index’s middle tier, such as India, the death rate climbed 20.7%. Smoke from cooking and heating with wood, coal and other solid fuels killed another two million people in their homes.
International development lenders committed $4.7 billion in 2024 to projects aimed at cutting air pollution, less than 1% of all development finance, according to a Clean Air Fund report.
The strategies of the world’s 100 largest oil and gas companies put them on track to produce 150% more in 2040 than their share under a 1.5°C pathway, up from 138% a year earlier, the report found.
The report also traces a decades-long disinformation and lobbying campaign by major oil companies, which had accurately projected dangerous warming by the early 1980s. It points to proposals from public health researchers and the UN to restrict fossil fuel advertising in the way tobacco ads were restricted.
“The tactics are very well described, and they include the manufacture of doubt,” Diarmid Campbell-Lendrum, who leads WHO’s climate change and health work, said on Monday at a separate webinar launching a paper on climate disinformation by a WHO civil society working group.
“The distraction onto other issues, trying to point the finger of blame at anything but tobacco consumption… are exactly the same tactics, and even in some cases the same players, which are now spreading climate disinformation.”
Image Credits: UNICEF, AP, WMO, International Confederation of Midwives, WMO, James Gathany/ PHIL, CDC, Public Domain, Chetan Bhattacharji.










































