As the climate warms, workers around the world are increasingly exposed to heat stress, reducing their ability to work safely and productively and creating substantial economic costs. A University of California, Davis study has quantified how rising temperatures affect global labour productivity and contribute to the broader economic costs of climate change.
Published in Nature Climate Change, the study estimates that each tonne of carbon dioxide emitted in 2025 causes about $41 in lost worker productivity. The researchers found that densely populated regions reaching critical combinations of heat and humidity are particularly affected, including parts of India, Nigeria, China and Pakistan, as well as the Middle East and sub-Saharan Africa.
Lead author Frances Moore, a professor in the UC Davis Department of Environmental Science and Policy, said the findings add to growing evidence about the real economic costs of climate change. According to the study, lost labour productivity is the second-largest contributor to the total social cost of carbon, behind heat-related deaths.
The social cost of carbon, or SC-CO2, measures the monetary damage caused by emitting one additional tonne of carbon dioxide. It can be used in cost-benefit analyses and decisions involving infrastructure, utility regulation and carbon policy. The researchers said their findings provide strong support for a social cost of carbon of about $200 per tonne.
To estimate the effects on workers, the researchers combined climate projections using the “wet-bulb globe temperature” (WBGT) with information about work intensity and outdoor exposure across jobs, regions and economic sectors. WBGT assesses heat stress by considering not only temperature but also factors such as humidity and wind that affect the body’s ability to release heat.
The impact of heat stress varies considerably by occupation and location. Agricultural and construction workers face particularly high exposure because their jobs often involve strenuous physical activity outdoors. Office and service workers generally face lower risks, but indoor workers can also experience dangerous heat when workplaces have limited or no air conditioning.
Access to cooling also differs dramatically between countries. The study noted that residential air-conditioning adoption across 33 countries ranged from virtually none in South Sudan to about 90% in Japan. These differences mean that workers facing similar temperatures may experience very different levels of heat exposure and productivity loss depending on local infrastructure and working conditions.
The researchers emphasised that air conditioning is not the only way to reduce heat-related risks. Providing shade, drinking water and adequate rest breaks, as well as shifting strenuous work to cooler hours when possible, can help protect workers. As extreme heat becomes more frequent and intense, the study suggests that employers and policymakers will increasingly need to treat heat as both a workplace health hazard and a significant economic challenge.
More information: Frances Moore et al, New labour and agricultural damages improve climate cost estimates, Nature Climate Change. DOI: 10.1038/s41558-026-02749-z
Journal information: Nature Climate Change Provided by University of California – Davis