Why is India reeling under a severe heatwave

Severe heat conditions have been consistently reported over large parts of India since the beginning of the summer season in March this year. With the weather department predicting little relief from extreme hot conditions, as another heatwave is expected to set in this week, many parts of India are broiled under severe heat and power outages due to the coal crisis in the country. Delhi recorded its second hottest April in 72 years, with the capital’s average monthly maximum temperature at 40.2 degrees Celsius. The last six weeks in Delhi have averaged more than 4 degrees Celsius above normal.

Rajasthan, on the other hand, got scorched under severe heat a week ago, with Dholpur being the hottest at 46.5 degrees Celsius; Jodhpur and Bikaner districts recorded maximum temperatures between 45 and 47 degrees Celsius on May 1. Climate change experts have said the duration of a severe heat wave is more worrying than the high temperatures. “The significance of the current Indian/Pakistani heat wave is less about smashing records and more about very long duration. The last six weeks have been repeatedly challenging the top of the historical range and baking this part of the world,” says Dr Robert Rohde, the lead scientist at Berkeley Earth.

While heatwaves are common in India, especially in May and June, summer began uncharacteristically early this year with high temperatures from March itself. As heatwaves also began setting in during the month, India recorded its warmest March: average maximum temperatures were the highest in 122 years. The ongoing heat waves that began on March 11 have affected at least 15 states and union territories. According to an analysis of the meteorological department’s data, Rajasthan and Madhya Pradesh have suffered the most with 25 days of heatwave and severe heat wave each. Himachal Pradesh, the otherwise cold hilly state known for its pleasant temperatures, experienced 21 heatwave days, followed by Gujarat (19) and Jammu and Kashmir (16). These states have recorded temperatures as high as 40 to 42 degrees Celsius.

Summers have always been gruelling in many parts of India, particularly in the northern and central regions. But experts say India is now recording more intense and frequent heatwaves, that are also longer in duration. While they agree that several atmospheric factors have led to the current heatwave, adding to that is global warming, which is the root cause for the increase in heatwaves. Climate scientists have looked at data for seventy years and at the intensity, the number of heatwaves, they say, is directly in response to global warming. Apart from climate change, some experts point to other challenges too, such as increasing population and the resultant strain on resources. This in turn leads to factors that worsen the situation, such as deforestation and increasing use of transportation.

“When you have more concrete roads and buildings, heat is trapped inside without being able to rise to the surface. This warms the air further,” says D Sivananda Pai, director of the Institute of Climate Change Studies. This is precisely the case in metro cities like Mumbai and Delhi where concrete roads have added to city temperatures, thus boosting the potency of heatwaves. Soaring temperatures aren’t just unpleasant, they can be lethal as well, with serious health consequences. The urban heat island effect is ever more worrisome because more and more people are moving into cities. And often the cost of extreme weather events like heatwaves and excess rain is disproportionately borne by the poor, who have less resources to cool down and fewer options to stay inside, away from the heat.

According to the World Bank, India’s annual temperatures increased at a rate of 0.62 degrees Celsius in the 100 years between 1901 to 2020. Heatstroke has killed 11,571 people in the last decade – from 2011 to 2020 in India, according to Accidental Deaths and Suicides in India data. In fact, heatstroke has claimed more lives than floods in India in the past two decades; it was the second leading cause of death from natural force in the country, after lighting. This phenomenon is, however, not limited to India. According to the World Health Organisation, across the world more than 1.66 lakhs deaths occurred due to heatwaves between 1998 and 2017.

There is no universally accepted definition of a heatwave; it differs from region to region. In India, the Indian Meteorological Department defines a heatwave for a region when temperatures cross 40 degrees Celsius in the plains, 37 degrees Celsius in coastal areas and 30 degrees Celsius

in the hilly regions. A severe heatwave is a condition when average temperatures rise to over 47 degrees Celsius, or 6.4 degrees Celsius above the normal. Many parts of India experienced a severe heatwave this year. While the Indian subcontinent is said to be at the tail end of a prolonged heatwave, caused by the La Nina phenomenon, that lasted nearly six weeks, resulting in the warmest March and April on record for the region, global warming is said to be the reason behind extreme weather conditions.

The fingerprints of climate change are all over the place, but it’s not being recognised fully. For instance, the heatwave power crisis was a headline news over the past few weeks in India. While the coal and power shortage has been attributed to poor management fuelled by populist free or subsidised power policies, the reason it boiled over now, is the extreme heat. It’s not just a hotter March and April, but the impact of climate change is here to stay and accelerate further, leading to more extreme weather events in future. Clearly, global warming is the cause of extreme weather conditions which are likely to result in more incidents of severe heat, extreme rainfall, and erratic monsoons in the coming decades as the planet warms.

Experts agree that several atmospheric factors have led to the current heatwave, adding to that is global warming, which is the root cause for the increase in heatwaves.