Heat That Slows Workers Down Was Missing From the Price of Carbon

A study published Sept. 16 in Nature Climate Change puts the cost of heat that slows workers down at roughly $41 for every ton of carbon dioxide emitted in 2025, a loss the authors say has been largely missing from the figures used to price emissions.

That figure is one piece of the social cost of carbon, a single dollar amount meant to stand for all the harm done by releasing one more ton of the gas. The paper adds worker heat to the damages that metric already counts and revises one of the older ones.

Frances Moore, an environmental scientist at the University of California, Davis, led the work. The senior author is Thomas Hertel, an agricultural economist at Purdue University. They and their colleagues built the estimate from climate-model projections of heat stress, corrected against observations. Into that went two published curves linking heat to how much work people get done, plus an economic model built to capture how economies adapt. Their stated 90% range runs from $1 to $108 a ton, and they report the figure as a modeled estimate rather than a measured cost. The losses are not spread evenly: they fall most heavily on South, East and Southeast Asia and Africa.

The same study also cuts the metric's farm damages. Drawing on evidence from the Intergovernmental Panel on Climate Change's Sixth Assessment Report, the researchers lowered estimated agricultural damages from $95 to $29 a ton. That cut is bigger than the labor cost they add, so the total comes down rather than up: the expected social cost of carbon for the same year goes from $204 to $179 a ton. The two changes together also sharply narrow the uncertainty around it.

The heat-stress and labor-capacity datasets, along with the code for the revised damage module, are publicly available on Zenodo and Code Ocean.