Record heatwaves in India may soon surpass human survivability limit

India logged its hottest February this year in 2023, following which is March 2022 which was the hottest ever and the third driest in 121 years.

The record heatwaves in India that have in recent years become more intense as well as more frequent could risk pushing India closer to the limit of human survival, claims a report by Kieran Hunt, a climate scientist at the University of Reading, who has studied the country’s weather and climatic patterns.

Heat stress for humans is a combination of temperature and humidity. India is typically more humid than equivalently hot places like Sahara, due to this sweating is less efficient or not efficient at all. Heat stress is measured by means of a wet-bulb reading – which combines air temperature and relative humidity and provides a better gauge of heat stress on the human body.

Alarmingly, a report by the World Bank in November cautioned that India could become one of the first places in the world where wet-bulb temperatures could soar past the survivability threshold of 35°C. At present, India’s wet-bulb temperature is about 32°C.

While no country is untouched by global warming, there are multiple reasons that make India an outlier. Explaining the reasons that account for India’s more intense heat waves, Hunt said, “All across India, since the pre-industrial period, the monthly average temperature has increased by about 1.5°C. Moreover, the urban heat island effect acts as a compounding factor that has added roughly an additional 2°C to the monthly average. Deforestation is also a major contributor.” The weather patterns – high pressure over north India, leading to dry, sunny, clear conditions with weak wind also play a role in the increased frequency of heatwaves.

In the report, Hunt stressed on the dangerous effect of these heat waves on India and its population, since when the temperatures stay higher for longer they tend to result in more fatalities, which is further excarbated by the rapid population increase over the last few decades leading to higher population density.

Another major danger is with India’s average temperature already being so high. In May, for example, the only places on the planet comparable in temperature to north India are the Sahara and parts of the inland Arabian peninsula, both of which are very sparsely populated. With the average temperatures already being so high, over 40°C, even small increases are likely to push close to human survival limits.

These extended and more frequent periods of heat waves can have wide-ranging detrimental effects on society. It can lead to significant drying of soil over large regions and also affect monsoon causing it to be uneven leading to poor water security and even localized flooding. The increased demand for cooling can strain the power grid and lead to increased greenhouse gas emissions; and general health risks, such as heatstroke, which disproportionately affect children, the elderly, and low-income communities.

Talking about ideas that can mitigate this damage on a policy level, Hunt suggested implementing urban planning guidelines that prioritize green spaces, shade, and ventilation in building design. At the corporate level: invest in research and development of low-energy cooling solutions, such as passive cooling systems, and promote energy-efficient building design. And for communities, encourage the use of cool roofs, green roofs, and tree planting to reduce the urban heat island effect.

India currently has over a 100 Heat Action Plans (HAPs) which are the primary policy response to economically damaging and life-threatening heat waves. They prescribe a number of activities, disaster responses, and post-heatwave response measures to reduce the impact of heat waves. However, on a concrete level, analysis of the plans shows that they are highly inefficient and poorly funded. Most of them do not explicitly carry out vulnerability assessments, leaving the authorities with little data on where to direct their scarce resources.

India logged its hottest February this year in 2023, following which is March 2022 which was the hottest ever and the third driest in 121 years. The year also saw the country’s third-warmest April, eleventh-warmest August, and eighth-warmest September since 1901.

Studies show India is one of the most exposed and vulnerable countries to heat. Between 1951 and 2016, three-day concurrent hot day and hot night events have increased significantly, and are projected to increase between two and four-fold by 2050 under the intermediate and high emission pathways of RCP 4.5 and RCP 8.5.

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