The Lancet: Global heat could lead to millions of premature deaths by 2050

A new modeling study published in The Lancet suggests that physical inactivity could increase by up to 1.75 percentage points, particularly in tropical low- and middle-income countries. This may result in an additional 0.47–0.70 million deaths annually by 2050 under high greenhouse gas emission scenarios.

Physical inactivity is already a major contributor to cardiometabolic diseases, accounting for about 5% of adult deaths. It is associated with $54 billion in healthcare costs and an additional $14 billion in productivity losses.

Currently, around one-third of the global population does not meet the World Health Organization’s physical activity recommendations. As temperatures rise, physical exertion places greater strain on the cardiovascular system, while extreme weather and worsening air quality further limit safe activity.

The model showed that when the average annual temperature exceeds 27.8°C, physical inactivity rises more sharply, with the greatest impact on women and older adults. Low- and middle-income countries are expected to be the most affected, with inactivity increasing by up to 1.85 percentage points. The most vulnerable regions include Central America, the Caribbean, eastern Sahel, and equatorial Southeast Asia.

Global productivity losses could reach $2.4–3.68 billion, while additional deaths linked to inactivity may account for up to 7–11% of all such deaths recorded in 2022. The greatest economic and health burden is expected in low- and middle-income countries, where people often have to work during the hottest hours and have limited access to air-conditioned environments, particularly women.

The authors emphasize the urgent need for action, including improving urban infrastructure to cool cities, creating shaded and reflective surfaces, ensuring access to affordable climate-controlled sports facilities, and implementing educational programs on safe physical activity in hot conditions.

The study has limitations: physical activity data were based on surveys and did not account for seasonal and age-related variations, types of activity, urbanization, migration, or extreme weather events, which may affect the accuracy of the projections.

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