Half a million additional people could die prematurely every year by 2050 as climbing global temperatures make physical activity increasingly dangerous or impossible, according to a major new study spanning more than 150 countries.
The research, published in The Lancet Global Health, tracked data from 156 nations between 2000 and 2022 and found a clear relationship between prolonged periods of extreme heat and declining activity levels across populations. Each extra month where average temperatures exceeded 27.8°C was associated with a 1.5 percentage point increase in physical inactivity globally — a figure that rose to 1.85 points in lower-income nations.
Researchers attributed the link to the physical toll heat places on the body, noting that high temperatures increase cardiovascular strain, accelerate dehydration and make exercise feel significantly harder due to elevated sweating and skin blood flow.
The economic consequences are projected to be severe alongside the human cost. Productivity losses tied to heat-driven inactivity could reach between $2.4 billion and $3.68 billion annually by mid-century, the study estimates.
The burden is not expected to fall evenly. Regions already experiencing high temperatures — including Central America, the Caribbean, eastern sub-Saharan Africa and parts of south-east Asia — face inactivity increases of more than four percentage points per additional hot month. Women and young people are identified as particularly exposed, in part because they have less access to climate-controlled spaces for exercise, while the public health systems in the most affected countries are least equipped to manage the resulting rise in chronic illness.
Physical inactivity is already estimated to account for around five percent of all adult deaths globally and is a recognised risk factor for cardiovascular disease, type 2 diabetes, certain cancers and mental health conditions.
The scale of the projected harm underlines why the study’s authors argue that physical activity should be treated as a climate-sensitive public health issue rather than purely a matter of personal choice.
On the question of what can be done, the research points to urban design as one practical lever — specifically the creation of shaded walking routes, reflective building surfaces, water features and covered public spaces that would allow activity to continue safely in hotter conditions. The authors note such infrastructure could also reduce heat-related sleep disruption and help protect cognitive performance and workplace productivity.
The findings arrive alongside a separate body of evidence reinforcing how much is at stake. Research published last year found that adults who move from inactive to active lifestyles cut their mortality risk by 22 percent. A further study in The Lancet Public Health found that reaching 7,000 steps a day was linked to meaningfully reduced risk across a wide range of conditions, with dementia risk falling by as much as 38 percent and cancer risk by around six percent.
