The role of urban green spaces in mitigating heat-induced labor productivity losses of global megacities

Hot and humid working conditions pose health risks and reduce productivity, which are exacerbated in the megacities by urban heat islands and global warming. Although urban green spaces are deemed as an effective cooling measure, their ability to alleviate heat exposure and deliver associated socio-economic benefits remains inadequately understood. Here we combine the Wet Bulb Globe Temperature (WBGT) with Normalized Difference Vegetation Index (NDVI) to quantify the cooling effects and benefits of urban green spaces for labor productivity during the warm season, and assess the associated economic gains for outdoor workers across 32 megacities worldwide. We find that urban green spaces lower WBGT by an average of 0.26 ± 0.02 °C in 2020, reducing productivity losses for moderate and heavy labor by 13.7 ± 2.04 % and 9.89 ± 1.88 %, respectively. This leads to a total increase of 343 million work hours and 4.7 billion dollars (constant 2005 PPP) in earnings. Prioritizing greening in labor-dense but sparsely vegetated areas would yield more cost-effective benefits, including an additional cooling potential of 0.75 °C, and an increase of ∼216–380 million work hours and median earnings gains of 39.7–71.7 million dollars per city. These findings emphasize the critical role of urban green spaces in protecting worker safety and the significant potential of enhanced greening strategies to maintain labor productivity.