Climate Inaction Is Killing Millions Each Year, Warns New Lancet Report

A new global report has sounded a stark warning that the world’s continued dependence on fossil fuels and sluggish climate action are already claiming millions of lives annually.

The 2025 Lancet Countdown on Health and Climate Change, produced in collaboration with the World Health Organization (WHO), reveals that 12 of 20 key indicators tracking climate-related health threats have reached record levels. The findings underscore how climate inaction is straining health systems, worsening inequality, and undermining economies worldwide.

“The climate crisis is a health crisis. Every fraction of a degree of warming costs lives and livelihoods,” said Dr. Jeremy Farrar, WHO Assistant Director-General for Health Promotion and Disease Prevention and Care. “This report makes clear that climate inaction is killing people now in all countries. However, climate action is also the greatest health opportunity of our time.”

Rising Heat Deaths and Economic Losses

The report highlights alarming trends. Heat-related deaths have increased by 23% since the 1990s, now averaging 546,000 deaths per year. In 2024, the average person experienced 16 days of dangerous heat that would not have occurred without climate change. Infants and older adults were hit hardest, each facing around 20 days of extreme heat annually, four times more than two decades ago.

The ripple effects of climate shocks are being felt across economies. Heat exposure caused an estimated 640 billion potential labour hours lost in 2024, equivalent to US$ 1.09 trillion in productivity losses. The costs of heat-related deaths among older adults reached US$ 261 billion.

Hunger and Food Insecurity Rising

Droughts and heatwaves are worsening global hunger. The report estimates that 124 million more people faced moderate or severe food insecurity in 2023 due to extreme weather.

Fossil Fuel Dependence Deepens the Crisis

Despite these alarming figures, many governments continue to pour money into fossil fuels. In 2023, net fossil fuel subsidies totaled US$ 956 billion, more than triple the funds pledged annually to help vulnerable nations adapt to climate change. Fifteen countries spent more on fossil fuel subsidies than on their entire national health budgets.

Health and Economic Benefits of Climate Action

Yet, the report also provides hope. Between 2010 and 2022, an estimated 160,000 premature deaths were avoided each year due to reduced coal-derived air pollution. Renewable energy now provides 12% of global electricity, supporting 16 million jobs. Meanwhile, two-thirds of medical students worldwide received education in climate and health in 2024, marking progress toward climate-resilient healthcare systems.

“We already have the solutions at hand to avoid a climate catastrophe,” said Dr. Marina Romanello, Executive Director of the Lancet Countdown at University College London. “Rapidly phasing out fossil fuels in favour of clean energy remains the most powerful lever to protect lives. Shifting to healthier, climate-friendly diets could also save over ten million lives a year.”

Health Sector Leads by Example

The report shows growing leadership within the health sector. Health-related greenhouse gas emissions fell 16% globally between 2021 and 2022, even as care quality improved.
WHO data indicate that 58% of Member States have completed a Health Vulnerability and Adaptation assessment, and 60% have finalized a Health National Adaptation Plan.

Cities and communities are also stepping up, with 834 out of 858 reporting cities completing or planning climate risk assessments. The clean energy transition is delivering measurable benefits, from cleaner air and healthier jobs to stronger local economies.

Looking Ahead to COP30 in Brazil

As the world prepares for COP30 in Belém, Brazil, WHO and partners are calling for health to be placed at the centre of climate action. WHO will release a Special Report on Climate Change and Health during COP30, outlining the policies and investments needed to safeguard lives and deliver the upcoming Belém Action Plan.

Now in its ninth year, the Lancet Countdown, led by University College London in partnership with WHO and 71 academic institutions, remains the world’s most comprehensive assessment of how climate change impacts health and how bold action can bring life-saving co-benefits.