Humid heat is already constraining labor productivity across much of the tropics and subtropics, and these losses are expected to accelerate as global temperatures rise. However, large uncertainties in future humid heat projections limit their value for risk assessment and adaptation planning. In this study, we identify two major sources of uncertainty in model projections of the Wet-Bulb Globe Temperature (WBGT), biases in baseline climatology and spread in projected changes, and address both using a bias correction emergent constraint method. This method allows us to reduce the projection error variance in heat-induced labor losses for 2051–2080 by more than 80% for most countries under different emissions scenarios. The improved projections reveal a pronounced and inequitable future: even under intermediate scenarios, labor productivity losses in the lowest-income countries could be up to sixteen times greater than those in the highest-income countries. These findings highlight the urgent need for targeted adaptation strategies to protect vulnerable workers in a warming world.
 

Climate projections,heat stress