Overview
- A peer‑reviewed study led by Stanford and published in The Lancet Planetary Health finds earlier global estimates used heat‑tolerance data from young, healthy adults and therefore understate risk to people aged 60 and over.
- The researchers used laboratory wet‑bulb experiments on older participants and age‑stratified population models to recalculate exposure to ‘uncompensable’ heat that the body cannot safely shed.
- At about 1.5°C of warming the study estimates roughly 22% of people aged 60+ — about 290 million — would face at least 180 hours of dangerous heat each year.
- The paper projects each extra degree of warming would expose about one billion more people to roughly another month of intolerable heat and warns of multi‑month, day‑and‑night danger in South Asia and the Persian Gulf near ~3°C.
- Authors link the findings to immediate policy needs: faster emissions cuts, targeted heat plans that prioritize older adults, and far wider access to safe cooling to reduce deaths, displacement, and climate migration.