Deadly Heat Stress to Become Commonplace Across South Asia Already at 1.5°C of Global Warming. Issue 7 (14th April 2021)

• Record Type: Journal Article
• Authors: Saeed, Fahad; Schleussner, Carl‐Friedrich; Ashfaq, Moetasim
• Is Part Of: Geophysical research letters. Volume 48:Issue 7(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-04-14
• Subjects: heat stress -- Paris Agreement -- South Asia; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1029/2020GL091191
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: South Asia (SA) is one of those hotspots where earliest exposure to deadly wet‐bulb temperatures ( T w >35°C) is projected in warmer future climates. Here we find that even today parts of SA experience the upper limits of labor productivity ( T w >32°C) or human survivability ( T w >35°C), indicating that previous estimates for future exposure to T w ‐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. Plain Language Summary: Wet bulb temperature ( T w ) thresholds of 32°C and 35°C are respectively considered as the upper limits of labor productivity and human survivability. Some areas in South Asia (SA) have already witnessed such heat stress conditions and their occurrences with larger geographical footprint are projected to become commonplace even at the 1.5°C Paris Agreement temperature. Risks at 2°C warming would be about twice as high compared to 1.5°C. Presently, the world is already 1°C warmer than the pre‐industrial period, and it may reach 1.5°C level by 2040, reflecting an imminent need for out of the box adaptation measures in SA. Key Points: Deadly heat stress conditions might become commonplace across South Asia even at 1.5°C warming Previous estimates of exposure to heat stress might have been conservative due to data biases Limiting global warming to 1.5°C instead of 2°C can reduce the projected population exposures to hazardous hot extremes by almost half