Rising Temperatures Intensify Humid Heat During India's Monsoon
A recent study finds that humid heat stress during India's monsoon season will rise sharply as global temperatures increase, affecting nearly half of the country if global temperatures exceed a 2°C rise.
The impact of climate change is being felt in India, where rising temperatures are intensifying humid heat during the monsoon season. A recent study published in AGU Advances projects that humid heat stress will rise sharply as global temperatures increase, affecting nearly half of the country if global temperatures exceed a 2°C rise.
## Introduction to Humid Heat Stress In India, the monsoon season is typically associated with relief from the scorching summer heat. However, with rising temperatures, the air has turned heavy, wet, and unbearable, forcing people like V. Kalaiselvi to retreat from their fields by 9 a.m. Kalaiselvi's daily ordeal is not an isolated weather anomaly, but rather a preview of what over half of India could experience if global temperatures exceed a 2°C rise.
## Impact on India The study notes that the actual physical land area in India which experiences uncoolable heat has grown by at least four times since the 1980s. The study finds that in the observed period, Uncompensable Heat Stress (UHS) affected 8% of India during the summer, but a negligible 1% during the monsoon. However, under a 2°C warming relative to the preindustrial period scenario, hot-humid heat stress during the monsoon season will surge to affect about half of the country - nearly the 60% that will be affected during summer.
| Region | Summer UHS | Monsoon UHS | 2°C Warming Monsoon UHS | | --- | --- | --- | --- | | India | 8% | 1% | 50% | | Eastern Coast | High | High | High | | Northwestern Regions | Low | High | High |
## Occupational Toll The researchers also evaluated a wide spectrum of physiological thresholds, applying lower limits for vulnerable groups and upper limits for acclimatised tropical populations. They found that occupational heat stress guidelines account for work intensity by recommending lower Wet-Bulb Globe Temperature (WBGT) limits as exertion increases. For continuous heavy work like agriculture or construction, the recommended WBGT limit is around 28°C for acclimatised workers, dropping even lower for unacclimatised seasonal labourers.
## Data Gap and Undercounting While the researchers drew upon four decades of weather and mortality records, the study explicitly noted the scarcity of public data dedicated to tracking heat-related deaths. Heat-related deaths are very complicated because India doesn't have cause-based mortality data, making it a complex, indirect process to correlate overall mortality data with temperature indices. India lacks a comprehensive system to monitor heat-attributable deaths or track emerging mortality trends, highlighting the need to update heat action plans and policies to include the impacts of humid heat.
