A recent study indicates that heat stress has led to a 10% reduction in productivity among migrant workers in India over the last four decades. Researchers from the Indian Institute of Technology Gandhinagar and other institutions highlight that the period of extreme heat is expected to increase, which poses serious challenges to the health and work capacity of these workers.
The study, published in the journal Earth”s Future, reveals that between 1980 and 2021, key rural-to-urban migration hotspots in northern, eastern, and southern India experienced a notable rise in humidity. This increase correlates with heightened heat stress in urban environments, particularly affecting the indoor conditions where many workers spend their time.
Major cities such as Mumbai, Delhi, Kolkata, and Hyderabad are receiving the most significant influx of migrants, contributing to a combined urban population of approximately 10 million. The study forecasts that as global warming progresses, each additional degree could further escalate heat stress levels, thereby diminishing the capacity of migrant workers to perform physically demanding jobs.
With migrant workers constituting a substantial segment of India”s workforce, a 2020 study published in The Indian Journal of Labour Economics noted that there were approximately 450 million internal migrants based on the 2011 Census. These individuals often engage in labor-intensive roles outdoors for extended hours, making them particularly susceptible to heat stress, which occurs when the body struggles to regulate its temperature in high-heat conditions.
The researchers emphasize that climate change has exacerbated heat stress, adversely affecting the productivity and income of outdoor workers, including migrants. They predict that the season characterized by extreme heat stress will extend, further complicating the overall well-being and work capability of these laborers.
Despite this clear impact, the specific effects of rising heat stress in urban areas on the work capacity of migrant laborers remain underexplored. By analyzing data from the 2011 Census and global climate models, the research focused on the top 50 urban areas in India where high numbers of individuals are likely unable to escape the heat.
The authors noted, “During the period from 1980 to 2021, most rural-to-urban migration hotspots in north, east, and southern India showed a significant increase in wet bulb temperature, indicating higher indoor heat stress.” They concluded that outdoor heat stress has increased considerably, resulting in an almost 10% drop in labor capacity in these regions.
Moreover, the study warns that nearly all urban areas in India could start experiencing high levels of indoor heat stress if global warming surpasses 2 degrees Celsius compared to pre-industrial levels. Under scenarios of 3 and 4 degrees Celsius of warming, typical labor capacity could decline to 71% and 62%, respectively, in stark contrast to a scenario maintaining current warming trends, where it would remain at 86%. The researchers also highlighted that outdoor workers in Chennai and parts of West Bengal could face productivity losses of up to 35% if wet bulb temperatures exceed 28 degrees Celsius.
