Remote sensing and GPS mobility reveal heat’s impact on human activity across diverse climates

Extreme heat increasingly threatens livelihoods and economies, killing more people yearly as temperatures rise globally and limiting productivity—often in countries that most need economic growth. Many studies document extreme heat's health and economic impacts, but few identify how different populations respond to extreme heat day-to-day. We introduce an approach for modeling human adaptation across diverse contexts, combining global weather and socio-economic data with GPS mobility. Using models fitting data in Indonesia, India and Mexico, we show extreme heat reduces urban mobility by up to 10%, concentrated midday. While heat generally reduces activity, very hot days and long heat waves may increase it, suggesting varied adaptations. Effects are stronger in poorer areas. Twinning these models with climate projections, we show that without adaptation mobility may fall 1-2% yearly, with certain seasons and places seeing greater declines.