New research from UC Davis, published in Nature Climate Change, puts a dollar figure on how heat stress from climate change cuts into worker productivity. The study estimates every ton of CO2 emitted in 2025 caused about $41 in lost labor output, with agricultural and construction workers hit hardest. Hot and humid regions like India, Nigeria, China, Pakistan, the Middle East and sub-Saharan Africa face the largest damages. The authors use wet-bulb globe temperature to account for humidity and wind, not just air temperature. They argue the numbers support a social cost of carbon around $200 per ton, similar to the EPA's 2023 estimate, and say labor losses are now the second largest component of climate damages after heat-related deaths. The paper also notes access to air conditioning varies widely, from 0% in South Sudan to 90% in Japan, so indoor workers without cooling are at risk too. For policymakers, the study strengthens the case for using the social cost of carbon in regulatory analysis and for workplace heat protections like shade, water, breaks and shifting hours.
