The annual number of preventable heat-related deaths globally has soared to more than half a million, a UCL-led report says.
The ninth annual Lancet Countdown on Health and Climate Change report reveals that the continued overreliance on fossil fuels and failure to adapt to climate change is being paid in people's lives, health and livelihoods.
It reveals that heat-related mortality per 100,000 has risen 23 per cent since the 1990s, with total heat-related deaths reaching an average of 546,000 annually between 2012 and 2021.
The scientists are calling for governments around the world to speed up the phasing out of fossil fuels to slow climate change and protect lives, saying that and other measures combined could save more than ten million lives a year.
Executive Director of the Lancet Countdown Dr Marina Romanello (UCL Institute for Global Health) said: "This year's health stocktake paints a bleak and undeniable picture of the devastating health harms reaching all corners of the world - with record-breaking threats to health from heat, extreme weather events and wildfire smoke killing millions.
"The destruction to lives and livelihoods will continue to escalate until we end our fossil fuel addiction and dramatically up our game to adapt.
"We already have the solutions at hand to avoid a climate catastrophe - and communities and local governments around the world are proving that progress is possible.
"From clean energy growth to city adaptation, action is underway and delivering real health benefits, but we must keep up the momentum.
"Rapidly phasing out fossil fuels remains the most powerful lever to slow climate change and protect lives.
"At the same time, shifting to healthier, climate-friendly diets and more sustainable agricultural systems would massively cut pollution, greenhouse gases and deforestation, potentially saving over ten million lives a year."
Prof Ollie Jay, of the University of Sydney, Australia, who was part of the analysis team, added that an average of 546,000 annual heat-related deaths globally amounted "approximately one heat-related death every minute".
"It is a really startling number and the numbers are going up. 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," he said.
Other key findings from the study include:
- In 2024 alone, air pollution from wildfire smoke was linked to a record 154,000 deaths.
- 2.5 million deaths every year are attributable to the air pollution that comes from continued burning of fossil fuels. This is also straining national budgets - as fossil fuel prices soared, governments collectively spent 956 billion US dollars on net fossil fuel subsidies in 2023. Meanwhile oil and gas giants keep expanding their production plans - to a scale three times greater than a liveable planet can support.
- On the other hand, an estimated 160,000 lives are being saved annually from the shift away from coal and the resultant cleaner air, while renewable energy generation reached record-highs.
Countries facing the worst consequences consistently track as the most politically engaged in climate change and health, yet they are being left behind in the clean energy transition, the report says.
Deeply unequal access to technology and clean energies is leaving the most vulnerable communities reliant on dirty, harmful fuels.
Just 3.5% of electricity comes from clean renewables in low-income countries compared with 13.3% in wealthy countries, while 88% of households in poorer countries still reply on polluting biomass to cook and heat their homes.
The report was produced in collaboration with the World Health Organisation and represents the work of 128 leading experts from 71 academic institutions and United Nations agencies globally.
Published ahead of the 30th UN Conference of the Parties (COP), the report provides the most comprehensive assessment to date of the connections between climate change and health, including new metrics which record deaths from extreme heat and wildfire smoke, the coverage of urban blue spaces (rivers, lakes, and coastlines), health adaptation funding and individual engagement with health and climate change.
