Climate inaction costs lives 

October 30, 2025

Heat-related deaths have surged by 63 per cent since the 1990s, averaging 546,000 fatalities annually between 2012 and 2021, according to a new Lancet Countdown on Health and Climate Change report released on Wednesday.

Authored by 128 international experts, the report highlights how insufficient climate action is costing millions of lives every year, driving extreme weather events such as floods, droughts, and wildfires, while also worsening the spread of infectious diseases.

Published ahead of the COP30 climate summit in Brazil, the report found that 12 of 20 key indicators tracking health threats have reached record levels. It warned that the global dependence on fossil fuels and the failure to adapt to rising temperatures are exacting a severe toll on public health and economic stability.

“The climate crisis is a health crisis. Every fraction of a degree of warming costs lives and livelihoods,” said Dr Jeremy Farrar, Assistant Director-General for Health Promotion and Disease Prevention and Care at the World Health Organization. He added that climate action offers a major health opportunity through cleaner air, better diets, and more resilient healthcare systems.

The report found that average global temperatures surpassed 1.5 degrees Celsius above pre-industrial levels for the first time in 2024. The average person was exposed to 16 days of dangerous heat last year, while infants and older adults experienced over 20 heatwave days each — four times higher than two decades ago.

Heat exposure led to the loss of 640 billion potential labour hours in 2024, translating into productivity losses worth 1.09 trillion dollars. The economic cost of heat-related deaths among older adults alone reached 261 billion dollars.

The frequency of extreme precipitation days increased across 64 per cent of global land between 1961-90 and 2015-24, heightening the risks of flash floods and landslides. Meanwhile, a record 61 per cent of land areas were affected by extreme drought in 2024 — 299 per cent higher than in the 1950s — threatening food, water, and sanitation systems and causing major economic losses.

Wildfire-related air pollution claimed 154,000 lives in 2024 due to increased small particulate matter (PM2.5) levels. The report also warned that climate change is expanding the transmission potential of diseases such as dengue, spread by Aedes mosquitoes.

In 2023, governments collectively spent 956 billion dollars subsidising fossil fuels — over three times the amount pledged to assist climate-vulnerable nations. Fifteen countries spent more on fossil fuel subsidies than on their entire national health budgets.

“Rapidly phasing out fossil fuels and shifting to renewable energy, sustainable agriculture, and healthier diets could prevent millions of deaths each year,” said Dr Marina Romanello, Executive Director of the Lancet Countdown at University College London.