Deadly Heat Stress to Become Commonplace Across South Asia Already at 1.5°C of Global Warming

Abstract

South Asia (SA) is one of those hotspots where earliest exposure to deadly wet‐bulb temperatures (Tw >35°C) is projected in warmer future climates. Here we find that even today parts of SA experience the upper limits of labor productivity (Tw >32°C) or human survivability (Tw >35°C), indicating that previous estimates for future exposure to Tw‐based extremes may be conservative. Our results show that at 2°C global warming above pre‐industrial levels, the per person exposure approximately increases by 2.2 (2.7) folds for unsafe labor (lethal) threshold compared to the 2006–2015 reference period. Limiting warming to 1.5°C would avoid about half that impact. The population growth under the middle‐of‐the‐road socioeconomic pathway could further increase these exposures by a factor of ∼2 by the mid‐century. These results indicate an imminent need for adaptation measures, while highlighting the importance of stringent Paris‐compatible mitigation actions for limiting future emergence of such conditions in SA.

Quantifying uncertainty in aggregated climate change risk assessments

“…5f ). Similar arguments could be made based on other risk assessments for India, where potentially deadly heat stress could become commonplace above 1.5 °C 35 .…”

Projected Changes in Socioeconomic Exposure to Heatwaves in South Asia Under Changing Climate

“…Saeed et al. (2021) found that the population growth would further increase with an exposure factor of ∼2 by the mid‐21st century relative to the base period. They also reported that most SA regions have already experienced such heat stress events with a larger geographical extent and are anticipated to become more hotspots even at the 1.5°C warming target.…”

Increased labor losses and decreased adaptation potential in a warmer world

“…In high humidity and temperatures, outdoor workers must slow work, hydrate, and take breaks in the shade to allow the body to cool off and maintain a safe internal body temperature or risk injury, illness, or death if they continue to work at high exertion levels 2 , 4 – 7 . Workers in many low-latitude locations already experience heat exposure that makes physical labor unsafe 1 , 8 – 10 . Labor productivity losses associated with reductions in work rate due to heat exposure can be as high as ~280–311 billion $US per year 11 , 12 , most of which are due to losses in low- and middle-income countries in heavy manual labor, such as agriculture and construction 11 , 13 , 14 .…”