The World Health Organization (WHO) and global partners have called on world leaders to place public health at the forefront of climate action, warning of escalating global health risks.
A new report released on Wednesday highlights that continued reliance on fossil fuels and insufficient adaptation measures are already causing severe harm to human health, economies, and ecosystems worldwide.
The 2025 Lancet Countdown on Health and Climate Change, produced in collaboration with WHO, found that 12 of 20 key indicators of climate-related health threats have reached record levels, reflecting the costs of inaction.
The report shows that climate inaction is costing lives, straining healthcare systems, and undermining economies, as environmental degradation and rising temperatures drive preventable diseases and premature deaths globally.
Dr Jeremy Farrar, WHO’s Assistant Director-General for Health Promotion, described the climate crisis as fundamentally a health crisis, noting that “every fraction of global warming directly endangers lives and livelihoods.”
He added that climate inaction is already claiming lives across all countries but stressed that decisive climate measures present opportunities for cleaner air, healthier diets, and stronger healthcare systems.
Key findings from the report include:
- Heat-related mortality has increased by 23% since the 1990s, accounting for 546,000 annual deaths.
- The average person endured 16 days of dangerous heat in 2024.
- Heatwaves and droughts worsened food insecurity, affecting 124 million people in 2023.
- Heat exposure led to 640 billion lost labor hours in 2024, equating to productivity losses of $1.09 trillion.
- Governments spent $956 billion on fossil fuel subsidies in 2023, three times the amount pledged for climate-vulnerable nations; fifteen countries spent more on fossil fuels than on national health budgets.
Despite these challenges, the report notes progress: renewable energy now accounts for 12% of global electricity generation, supporting 16 million jobs and preventing an estimated 160,000 premature deaths annually from reduced coal pollution between 2010 and 2022.
Dr Marina Romanello, Executive Director of the Lancet Countdown at University College London, said that existing solutions could prevent a climate catastrophe. “Cities and communities are already achieving meaningful health and environmental gains,” she said.
Romanello stressed that phasing out fossil fuels in favor of renewable energy and sustainable food systems could save over 10 million lives annually while drastically reducing pollution and deforestation.
She also noted that, despite slower government commitments, cities and health systems are taking the lead: nearly all reporting cities have completed or are planning climate risk assessments to safeguard public health.
Cleaner energy transitions are also generating healthier jobs, economic growth, and investment, with global health-related greenhouse gas emissions falling 16% between 2021 and 2022.
WHO data shows that 58% of member states have completed Health Vulnerability and Adaptation Assessments, while 60% have finalized National Health Adaptation Plans to prepare for future climate risks.
As the world prepares for COP30 in Belém, Brazil, Romanello said the 2025 Lancet Countdown findings provide critical evidence to accelerate health-centered climate action and inform the forthcoming Belém Action Plan.
The Lancet Countdown, established in partnership with Wellcome and led by University College London with WHO and 71 global institutions, remains the most comprehensive assessment of health impacts from climate change.
