UC Davis study: Heat stress adds $41 per tonne to carbon cost

A study published in Nature Climate Change estimates that heat-related losses in labor productivity will add approximately $41 to the economic damage caused by each tonne of CO2 emitted in 2025. This figure represents the modeled present value of future output losses due to warming, rather than a direct fee.

Researchers from the University of California, Davis, utilized wet-bulb globe temperature (WBGT) metrics to account for humidity, wind, and radiant heat. The findings suggest that heat-related productivity loss is the second-largest component of the “social cost of carbon,” trailing only heat-related deaths. The study supports a total social cost of carbon value of roughly $200 per tonne, aligning with previous US Environmental Protection Agency estimates.

Workers in agriculture, construction, and outdoor industries are most at risk, though indoor employees without adequate cooling are also vulnerable. The economic impact is expected to be disproportionately high in South Asia, East Asia, Southeast Asia, and Africa, where high heat exposure often coincides with physically demanding labor and limited access to cooling infrastructure.