Global heat stress health impacts

In early July 2026 a briefing warned that extreme heat could place up to 70 % of the world’s population at risk. By late July a study of 751 sites in 26 countries projected rising suicide deaths linked to temperature and highlighted acute heatstroke risks, especially in Tunisia, urging cooling, hydration and medical care.

New research released on 27 July estimates that by 2050 extreme heat could add roughly 430,000 deaths each year, with the heaviest burden in low‑income nations lacking reliable electricity and air‑conditioning. The Climate Impact Lab identifies 18 high‑risk countries—mostly in northern sub‑Saharan Africa (Niger, Mali, Burkina Faso, Chad) and South Asia (Pakistan, Bangladesh, Nepal, Myanmar)—home to about 676 million people, where up to 377,000 deaths could occur annually.

A parallel study in *Nature Climate Change* finds hazardous heat stress has risen globally over the past five decades. About 70 % of the world’s population now experiences at least 90 days of strong heat stress per year, up from 55 % in the 1970s, and nighttime “feels‑like” temperatures are increasing faster than daytime highs. Recent European heat waves have already caused over 10,000 excess deaths, confirming heat as the deadliest extreme‑weather threat for children, the elderly and those with pre‑existing conditions.

Both reports call for urgent, equitable climate finance and stronger heat‑health action plans to protect vulnerable populations.