Overview
- Analyzing 156 countries from 2000–2022, the study links each additional month above 27.8°C (82°F) to roughly a 1.5 percentage-point increase in global physical inactivity, rising to about 1.85 points in low- and middle-income countries.
- By 2050, the projections translate into an estimated 470,000–700,000 extra premature deaths each year and US$2.4–3.68 billion in annual productivity losses.
- The sharpest increases are expected in Central America, the Caribbean, eastern Sub‑Saharan Africa, and equatorial Southeast Asia, with country estimates including about 10.6 deaths per 100,000 in India and up to 70 per 100,000 in Somalia.
- High-income countries appear more buffered on average but are not exempt; the United States could see roughly 2.5 deaths per 100,000 linked to heat-related inactivity by mid-century.
- The authors note uncertainties from self-reported activity data and temperature-only scenarios, and recommend cooler urban design, affordable climate-controlled exercise access, clearer heat-safe activity guidance, workplace protections, and stronger emissions reductions.