It says the world’s addiction to fossil fuels also causes toxic air pollution, wildfires and the spread of diseases such as dengue fever, and millions each year are dying owing to the failure to tackle global heating.
The report, the most comprehensive to date, adds the damage to health will get worse with leaders such as Donald Trump ripping up climate policies and oil companies continuing to exploit new reserves.
Governments gave out $2.5bn a day in direct subsidies to fossil fuels companies in 2023, the researchers found, while people lost about the same amount because of high temperatures preventing them from working on farms and building sites.
Reduced coal burning has saved about 400 lives a day in the last decade, the report says, and renewable energy production is rising fast. But the experts say a healthy future is impossible if fossil fuels continue to be financed at current rates.
Dr Marina Romanello, of University College London (UCL), who led the analysis, stated: “This [report] paints a bleak and undeniable picture of the devastating health harms reaching all corners of the world. The destruction to lives and livelihoods will continue to escalate until we end our fossil fuel addiction.”
“We’re seeing millions of deaths occurring needlessly every year because of our delay in mitigating climate change and our delay in adapting to the climate change that cannot be avoided. We’re seeing key leaders, governments and corporations backsliding on climate commitments and putting people increasingly in harm’s way.”
The report says the rate of heat-related deaths has surged by 23% since the 1990s, even after accounting for increases in populations, to an average of 546,000 a year between 2012 and 2021.
“That is approximately one heat-related death every minute throughout the year,” said Prof Ollie Jay, of the University of Sydney, Australia, who was part of the analysis team.
“It is a really startling number and the numbers are going up.”
Jay stated: “We constantly emphasise to people that heat stress can affect everybody and it can be deadly – I think a lot of people don’t understand that – and that every heat-related death is preventable.”
Laura Clarke, the chief executive of the environmental law firm ClientEarth, noted, “We are living through the era of climate consequences. Heatwaves, floods, drought and disease are no longer distant warnings – they’re here now. But as attribution science, climate litigation and grassroots activism grow, accountability for climate impacts is no longer a question of if but when.”
The 2025 edition of the Lancet Countdown on Health and Climate Change was led by UCL in collaboration with the World Health Organization and produced by 128 experts from more than 70 academic institutions and UN agencies.
In the past four years, the average person has been exposed to 19 days a year of life-threatening heat and 16 of those days would not have happened without human-caused global heating, the report says. Overall, exposure to high temperatures resulted in a record 639bn hours of lost labour in 2024, which caused losses of 6% of national GDP in the least developed nations.
The continued burning of fossil fuels not only heats the planet but also produces air pollution, causing millions of deaths a year. Wildfires, stoked by increasingly hot and dry conditions, are adding to the deaths caused by smoke, with a record 154,000 deaths recorded in 2024, the report says. Droughts and heatwaves damage crops and livestock and 123 million more people endured food insecurity in 2023, compared with the annual average between 1981 and 2010.
Despite the harm, the world’s governments provided $956bn in direct fossil fuel subsidies in 2023, which was the world’s hottest year on record until it was surpassed by 2024. The researchers said this dwarfed the $300bn a year pledged at the UN climate summit Cop29 in 2024 to support the most climate-vulnerable countries.
The report adds the UK provided $28bn in fossil fuel subsidies in 2023 and Australia allocated $11bn. Fifteen countries including Saudi Arabia, Egypt, Venezuela and Algeria spent more on fossil fuel subsidies than on their national health budgets.
The world’s 100 largest fossil fuel companies increased their projected production in the year up to March 2025, which would lead to carbon dioxide emissions three times those compatible with the Paris climate agreement target of limiting heating to 1.5C above preindustrial levels, the report says. Commercial banks are supporting this expansion, with the top 40 lenders to the fossil fuel sector collectively investing a five-year high of $611bn in 2024. Their green sector lending was lower at $532bn.
Romanello said: “If we keep on financing fossil fuels and enabling this expansion of fossil fuels, we know that a healthy future is not possible.”
She stated the solutions to avoid a climate catastrophe and protect lives existed, from clean energy to city adaptation to healthier, climate-friendly diets.
“If there’s any optimism it comes from the action by local communities and authorities, and by the health sector – those that are really in contact with people on the ground,” she continued.
“They are seeing the impacts with their own eyes and are stepping up because they just become undeniable, but we must keep up the momentum.”
