Mercury rising: India hit with second heatwave this month

Even though summer is a month away, parts of India are already in the middle of a second heatwave in March, recording temperatures above 40°C 

After experiencing a heatwave in early March, India is in the middle of another one at the end of the month. Parts of Rajasthan, Gujarat, Maharashtra, and adjoining areas of Madhya Pradesh and Telangana saw temperatures soar well above 40°C. Delhi, Mumbai, and Lucknow recorded temperatures of 38.1°C, 38.2°C and 39°C, respectively, between March 21 and March 24. 

Mahesh Palawat, AVP-Meteorology and Climate Change, Skymet Weather, said the absence of any weather system and presence of an anticyclone over Rajasthan and adjoining Pakistan had been pushing hot winds across North and Central India. “March is going to end on a hotter note with no respite till the beginning of April. Light winds and dry weather will once again increase temperatures over Northwest India leading to heatwave conditions,” he warned. 

The IPCC’s WGII report on Climate Impacts, Vulnerability & Adaptation warned that if emissions are not rapidly eliminated, heat and humidity will create conditions beyond human tolerance, with India being on top of that list. 

The graphs represent the year-on-year increasing temperatures for three years in four Indian cities. Data courtesy: Ogimet

Warming cities, weakening economy

It’s not mercury alone that is soaring in India. The rate of urbanisation is rising, too. India is likely to add 416 million urban dwellers between 2018 and 2050. While urbanisation is essential for economic growth, its contribution to global warming is undeniable.  

“With development, the weather of the cities has also completely changed. Concrete and built-up materials have been keeping the weather hot by trapping the winds. The Urban Heat Island (UHI) effect is playing a major role in heating up urban areas. Loss of green cover and absence of enough shade to accommodate more people in a city would have a devastating impact on public health,” added Palawat. 

Even in the same city, the impacts of heat are not felt equally. People with no access to cooling devices or those who work outdoors like construction workers, street vendors, etc. are likely to suffer more. 

While both rural and urban populations are vulnerable to heat-related mortality, people with no access to cooling devices, individuals living in communities with less green space, or those who work outdoors like construction workers, street vendors, etc. are more susceptible to heat-related mortality.

Adding fuel to the fire: Wet-bulb temperatures

Currently, wet-bulb temperatures in India rarely exceed 31°C, with most of the country experiencing maximum wet-bulb temperatures of 25-30°C. 

Even if emissions are cut by the levels currently promised, many parts of northern and coastal India would reach extremely dangerous wet-bulb temperatures of over 31°C towards the end of the century. If emissions continue to climb, wet-bulb temperatures will approach or surpass the unsurvivable limit of 35°C throughout much of India, with the majority of the country reaching wet-bulb temperatures of 31°C or more, according to the IPCC’s Working Group II report. 

A wet-bulb temperature of 31°C is extremely dangerous for humans, while a value of 35°C is unsurvivable for more than about 6 hours.

In terms of economy, India currently loses around 259 billion hours annually due to the impacts of humid heat on labour, up from a previous estimate of 110 billion hours. 

What to expect?

Such extreme events will considerably increase poor health and premature deaths. Without additional adaptation, the population exposure to heatwaves will continue to increase with additional warming, resulting in heat-related mortality.

Increased heat is also pressurising food production in vulnerable regions with increasing frequency, intensity, and severity of droughts and heatwave conditions.

As for this heatwave, it will stay a while as pre-monsoon activities are predicted to commence only around mid-April across Northwest India.  

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