A global failure to adapt to climate change is costing millions of lives annually, according to a major new report published by The Lancet on Wednesday. The study warns that worsening heatwaves, extreme weather, and pollution linked to fossil fuel use are driving an escalating global health crisis.
The Lancet Countdown on Health and Climate Change, now in its ninth year, is led by University College London in collaboration with the World Health Organization. It provides one of the most comprehensive assessments to date of how climate change is affecting human health worldwide.
“This year’s health stocktake paints a bleak and undeniable picture of the devastating health harms reaching all corners of the world,” said Dr. Marina Romanello, executive director of the Lancet Countdown at UCL. “Record-breaking threats from heat, extreme weather, and wildfire smoke are killing millions. The destruction to lives and livelihoods will continue until we end our fossil fuel addiction and dramatically increase our efforts to adapt.”
The report found that 12 of the 20 key health indicators linked to climate change reached record highs this year. These include worsening food insecurity, higher exposure to dangerous heat, and rising pollution levels.
Heat-related deaths have surged by 23% since the 1990s, now claiming around 546,000 lives a year. In 2024 — the hottest year ever recorded — the average person experienced 16 more health-threatening hot days compared to previous decades. Air pollution from wildfire smoke was linked to 154,000 deaths last year, the report added.
The continued reliance on fossil fuels remains one of the largest drivers of climate-related mortality. Air pollution from burning coal, oil, and gas is responsible for 2.5 million deaths annually, while the use of dirty fuels in homes caused a further 2.3 million deaths in 2022 across 65 countries. The report also noted that global energy-related emissions have reached unprecedented levels, with fossil fuel giants planning production at nearly three times the volume compatible with a livable planet.
The authors warned that adaptation funding remains “grossly insufficient,” particularly in lower-income nations most vulnerable to the effects of climate change. Romanello criticised recent political backsliding on foreign aid and climate finance, saying it leaves “populations increasingly unprotected.”
Despite these challenges, the report also highlighted progress. A shift away from coal in wealthier nations prevented an estimated 160,000 premature deaths each year between 2010 and 2022, while renewable energy generation reached record levels in 2022.
“Climate change action remains one of the greatest health opportunities of the 21st century,” said Tafadzwa Mahbhaudi, director of the Lancet Countdown Africa. “It can drive innovation, create jobs, reduce energy poverty, and build resilience to the impacts already being felt.”
The findings underscore an urgent call for world leaders ahead of global climate talks later this year: tackling climate change is no longer just an environmental issue — it is a global health emergency.