Migrant workers’ productivity: Rising heat and humidity have chipped away at the productivity of India’s migrant workforce, with outdoor heat stress tied to an estimated 10% decline in labour capacity over the past four decades, according to new research led by IIT Gandhinagar and published in Earth’s Future.
The analysis links the drop to steadily worsening outdoor conditions across rural-to-urban migration “hotspots” in the north, east and south, and to a parallel rise in indoor heat stress, signalled by higher wet-bulb temperatures.
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Using 2011 Census data and global climate models across the 50 largest urban areas, the team found that cities drawing the most migrants, like Mumbai, Delhi, Kolkata and Hyderabad, face some of the starkest risks. As global temperatures climb, the season of extreme heat stress is expected to lengthen, cutting workers’ ability to perform physically demanding jobs and straining incomes and health.
The projections are sobering. If warming tops 2°C above pre-industrial levels, most Indian cities could see consistently high indoor heat stress. Typical labour capacity, the study estimates, would fall from 86% under current-trend scenarios to 71% at 3°C of warming and 62% at 4°C. In places like Chennai and parts of West Bengal, outdoor workers performing moderate to heavy tasks could see productivity losses up to 35% when wet-bulb temperatures exceed 28°C.
India’s internal migrants, at 450 million in the 2011 Census and comprising up to 42% of the population in some estimates, are particularly exposed because many work long hours outdoors or in poorly cooled spaces. The authors warn that without rapid adaptation, cooling access, work-rest scheduling, shade and hydration standards, and accelerated emissions cuts, heat stress will increasingly erode livelihoods and urban productivity.
