Rising global temperatures may be quietly reshaping human behaviour and health by pushing millions towards physical inactivity, according to a new modelling study published in The Lancet Global Health.

As climate change intensifies heat exposure worldwide, researchers warn that even small increases in temperature could significantly reduce people’s ability to stay active. Analysing data from 156 countries between 2000 and 2022, the study projects that by 2050, each additional month with average temperatures above 27.8°C could raise global physical inactivity by 1.5 percentage points.

The impact is expected to be more pronounced in low- and middle-income countries, where inactivity could rise even further. Regions such as Central America, the Caribbean, Eastern Sub-Saharan Africa, and Equatorial Southeast Asia may face the steepest increases, driven by prolonged exposure to extreme heat.

The consequences extend beyond lifestyle changes. Researchers estimate that rising inactivity linked to climate change could contribute to between 470,000 and 700,000 premature deaths annually, alongside billions of dollars in lost productivity. While these findings are based on projections, experts stress the urgency of action.

Measures such as designing cooler cities, expanding access to safe indoor exercise spaces, and reducing greenhouse gas emissions may help mitigate the growing health risks of a warming world.