The World Health Organisation (WHO) and global partners have warned that the worsening climate crisis has escalated into a full-blown health emergency, as new data reveal record levels of heat-related deaths, food insecurity, and economic strain.
The 2025 Lancet Countdown on Health and Climate Change report, produced in collaboration with WHO shows that 12 out of 20 key indicators tracking health threats have reached record highs, highlighting how climate inaction is already costing lives and undermining global economies.
According to the report, rising temperatures are driving a 23% increase in heat-related deaths since the 1990s, with an average of 546,000 deaths annually linked to extreme heat.
In 2024, the average person endured 16 days of dangerous heat that would not have occurred without human-induced climate change. Vulnerable populations, including infants and the elderly , faced more than 20 heatwave days per person, a fourfold rise in the past two decades.
“The climate crisis is a health crisis. Every fraction of a degree of warming costs lives and livelihoods,” said Dr. Jeremy Farrar, WHO’s Assistant Director-General for Health Promotion, Disease Prevention and Care.
“This report, produced with WHO as a strategic partner, makes clear that climate inaction is killing people now in all countries. However, climate action is also the greatest health opportunity of our time. Cleaner air, healthier diets, and resilient health systems can save millions of lives now and protect current and future generations.”
The report paints a grim picture of climate-driven economic and social impacts.
In 2024 alone, heat exposure caused 640 billion potential labour hours to be lost, equating to productivity losses of Sh143.88 trillion, while the costs of heat-related deaths among older adults reached Sh34.45 trillion.
Additionally, droughts and heatwaves left 124 million people facing moderate or severe food insecurity in 2023.
Despite mounting evidence, governments continue to pour funds into fossil fuels, with Sh126.19 trillion spent on subsidies in 2023 more than triple the amount pledged to support climate-vulnerable nations.
Fifteen countries spent more on fossil fuel subsidies than their entire national health budgets.
The Lancet Countdown report also highlights progress and opportunity. Between 2010 and 2022, 160,000 premature deaths were avoided annually thanks to reductions in coal-derived air pollution. Renewable energy now provides 12% of global electricity and supports 16 million jobs worldwide.
“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, renewable energy remains the most powerful lever to slow climate change and protect lives.”
As the world prepares for COP30 in Belém, Brazil, WHO is calling for health protection to be placed at the centre of global climate action.
The upcoming COP30 Special Report on Climate Change and Health will outline policies and investments needed to safeguard health, equity, and resilience in a rapidly warming world.
