Climate & Environment

Heat‑Related Deaths Surge 36% Since Paris Agreement, Report Finds

By Ridhima Gupta, Jasjeev Gandhiok

The Lancet Countdown on Health and Climate Change’s 10th indicator report, released on Wednesday, shows that the annual average of heat‑related deaths worldwide rose by nearly 36% between 2016 and 2025, the decade since the Paris Agreement entered into force. Human‑made climate change is responsible for more than 70% of the 710,000 heat‑related deaths recorded in 2023 alone.

India is a key focus of the report. People in the country were exposed to over 2,600 hours per year during which heat posed a moderate or higher risk of heat stress during moderate outdoor physical activity—more than 200 hours above the 1990s average. The report also notes that Indians lost an estimated 64 hours of sleep annually between 2021 and 2025 due to high night‑time temperatures, about three hours more per year than the 1986‑2005 period.

The report, led by University College London and produced with the World Health Organization, calls for climate change to be formally recognised as a global health emergency and for health to be central to decisions on emissions reduction, adaptation and climate funding.

Key findings include: - Heat was linked to an average of 540,800 estimated deaths per year from 2016 to 2023, with 68% caused by climate change, up from 55% in 2006‑2015. - In 2023 alone, heat was linked to a record 710,000 deaths, exceeding those from malaria or HIV, with 71.5% driven by climate change. - Climate change is estimated to have caused almost 3 million heat deaths between 2016 and 2023. - Extreme drought affected nearly 52% of the world’s land for at least a month in 2025, the second‑highest level on record. - Very extreme rainfall now covers about 17.2% of global land each year in 2016‑2025, up from 14.8% in the previous decade.

The report also highlights the health benefits of clean energy. Worldwide clean‑energy investment reached a record US$2.1 trillion in 2025, almost double fossil‑fuel investment, and cleaner air has prevented an estimated 323,000 deaths a year in at least 77 countries.

The authors urge a coordinated global response, including a new WHO instrument, faster and fairer greenhouse‑gas emission cuts, sustained research investment and climate finance as grants rather than loans to avoid debt for vulnerable countries.

The report is based on the work of 146 multidisciplinary researchers from more than 100 institutions across more than 30 countries and tracks 54 indicators of the health impacts of climate change, including four new indicators introduced this year.