The Wire Staff 
Kochi: The duration of heatwaves in India increased by about 2.5 days between 1961 and 2021 due to global warming, as per a report released by the India Meteorological Department on April 26.
And it’s only likely to increase further. By 2060, there will be an increase of about two heatwaves per season; the duration of heatwaves too will rise by 12-18 days by this year. Currently, on average, the maximum duration of a heatwave is two to four days.
A comprehensive response plan that integrates adaptation measures including technological ones – such as developing early warning systems – is the need of the hour, according to the report.
Heatwave duration rises
As per the IMD, a heatwave is said to occur when the average maximum temperature is 4.5-6.4º C above the long-term average (or above 40º C in the plains, 30º C in hilly areas, or 37º C in coastal areas).
A monograph titled “Heat and Cold Waves in India: Processes and Predictability” was released on April 26 by M. Ravichandran, Secretary, Ministry of Earth Sciences (MoES). Per the report, published by the MoES, IMD and Indian Institute of Tropical Meteorology, heat waves occur in primarily two regions in India, central and north-western India as well as coastal Andhra Pradesh.
On average, the maximum duration of a heatwave is two to four days. In some areas in central and north-western India, it is more than six days, and in coastal Andhra Pradesh, more than eight. The longest heatwave exceeded a duration of 10 days at many stations in central and northwestern India, and coastal Andhra Pradesh, the report noted.
The average heatwave days are more during the El Nino years when compared to the La Nina years. An El Nino year is associated with periods of warm weather caused due to the El Niño–Southern Oscillation (ENSO), an oceanic and atmospheric phenomenon. The La Nina is the cooler phase of the ENSO and is associated with cooler weather.
Per the report, both the frequency and duration of heatwaves are increasing over central and north-western India as well as coastal Andhra Pradesh and Odisha. Between 1961 and 2021, the duration of heat waves in India increased by about 2.5 days due to global warming.
Model estimates also suggested that by 2060, there will be an increase of about two heatwaves and an increase in the duration of heatwaves by 12-18 days. Northwest India could experience about four heatwaves per season, of a total duration of 30 days.
The report also warned that heatwaves could spread to southern India.
“In the future climate change scenario, the southern parts of India and the coastal areas of India, which are not currently affected by heatwaves, are likely to be affected by heatwaves,” it stated.
Need for a comprehensive response plan
According to the document, the “most effective way” to deal with heat waves is to develop a “comprehensive response plan” using an integrated approach that combines individual strategies. Adaptations to the heatwaves – that encompass cultural, institutional, technological and ecosystem-related measures – should be part of this too.
Also read: How Can India Adapt Better to Heatwaves?
For instance, some of the best adaptive measures include increasing public awareness (so that people know the signs of heat-related illnesses such as strokes, and are aware of ways to protect themselves). Enabling heat-resilient construction (such as by ensuring better-ventilated buildings and planning for more trees in urban areas to increase green cover), changing work timings to ensure workers are not out in direct sunlight during heatwaves, and developing early warning systems are others.
India does have some of these measures in place. The IMD, for instance, issues heatwave warnings for the country around a week in advance. However, all these measures need to be implemented on a “large scale” to really reduce the impacts of heatwaves in India, the report stated.
There is a “need for greater inter-agency collaboration on heatwave impacts and adaptation”, the report also noted. It is also “high time” that the IMD systematically researches the health implications of the increasing heat and humidity in India, it added.
Deaths and other impacts
Tackling heatwaves is important because higher temperatures can cause a range of illnesses, from dehydration, heat exhaustion and stroke, to cardiovascular problems and even death in people who have pre-existing health conditions.
At least 11 people died and more than 600 others suffered from heat-related health issues after they stood out in the open for more than five hours in Maharashtra’s Navi Mumbai on April 16. A recent study in the journal Lancet found a 55% increase in deaths due to extreme heat between 2000-2004 and 2017-2021 in India.
Heatwaves affect the economy too. The Climate Transparency Report 2022 found that India suffered an income loss of 5.4% of its Gross Domestic Product (GDP), the highest among the G20 nations in 2021, after a severe heatwave that year affected workers, low-income households and farmers.
Climate change has been a factor in the increasing occurrence and intensity of heatwaves. For instance, the heatwaves that swept across north and northwest India in the summer of 2022 were 30 to 100 times more likely due to climate change, two separate reports had found.