Estimating global labor productivity losses from heat stress under a range of long-term climate scenarios

Extreme heat is among the deadliest meteorological hazards and poses an increasing threat to human health and socioeconomic systems, including labor productivity.

Here, we present global and regional projections of population exposure to extreme heat stress and associated labor productivity losses across a range of emissions scenarios from the Shared Socioeconomic Pathways (SSPs) and NGFS (Network for Greening the Financial System), which are widely employed in private and financial sector risk assessments.

Robust projections of heat stress impacts require climate data that accurately represent temperature and humidity conditions during the hottest hour of the day, when physiological strain typically peaks. To this end, our analysis builds on a newly derived global dataset of future changes in the Heat Index (HI), a widely used metric of human heat stress integrating the combined effects of temperature and humidity, with enhanced temporal accuracy. Sub-daily relative humidity during the hottest hour is reconstructed from ISIMIP3 daily near-surface specific humidity using a physically and statistically consistent correction framework, enabling a more realistic representation of peak heat stress than standard ISIMIP3 humidity output.

Our results reveal pronounced hotspots of intensifying heat stress and labor productivity losses in densely populated low-latitude regions, including South Asia and West Africa, that are strongly dependent on labor-intensive sectors. In these regions, most projected heat-related productivity losses could be avoided by limiting global warming to 1.5 °C.