Heatwave in India: 90% of India, entire Delhi in 'danger' zone of heatwave impacts, finds study

About 90 per cent of India is in the "extremely cautious" or "danger" zone from heatwave impact and almost all of Delhi is particularly vulnerable to severe heatwave impacts, says a new study.

The study, conducted by Ramit Debnath and colleagues at the University of Cambridge, suggested that heatwaves have impeded India's progress towards achieving the United Nations' Sustainable Development Goals (SDGs) more significantly than previously thought. Furthermore, it added that the current assessment metrics may not fully capture the impacts of heatwaves linked to climate change on the country.

The study comes after 13 people died from heatstroke at a Maharashtra government award function in Navi Mumbai. It became one of the highest death tolls from a single heatwave-related event in the country's history.

Heatwaves have claimed more than 17,000 lives in 50 years in India, according to a paper authored by M Rajeevan, former secretary of Ministry of Earth Sciences, along with scientists Kamaljit Ray, S S Ray, R K Giri and A P Dimri. The paper published in 2021 said there were 706 heatwave incidents in the country from 1971-2019.

The threshold for a heatwave is met when the maximum temperature of a station reaches at least 40 degrees Celsius in the plains, at least 37 degrees Celsius in coastal areas, and at least 30 degrees Celsius in hilly regions, and the departure from normal is at least 4.5 degrees Celsius.

Researchers at the University of Cambridge conducted an analytical evaluation of the country's heat index with its climate vulnerability index to assess India's climate vulnerability and the potential impact of climate change on SDG progress, PTI reported.

The heat index (HI) is a measure of how hot it feels to the human body, taking into account both temperature and humidity. The climate vulnerability index (CVI) is a composite index that uses various indicators to account for socioeconomic, livelihood, and biophysical factors to study the impact of heatwave.

The researchers accessed a publicly available dataset on state-level climate vulnerability indicators from the government's National Data and Analytics Platform to classify severity categories.

They then compared India's progress in SDGs over 20 years (2001-2021) with extreme weather-related mortality from 2001-2021.

According to the study, more than 90 per cent of India is in the "extremely cautious" or "danger" range of heatwave impacts through HI, otherwise considered "low" or "moderate" vulnerability through CVI.

Through the study, the authors concluded that the use of CVI may underestimate the actual burden of climate change concerning heat and suggested that India should consider reassessing its climate vulnerabilities to meet the SDGs.

They warned that if India fails to address the impact of heatwaves immediately, it could slow progress towards achieving sustainable development goals.

The current heat-action plans designed and implemented according to the Delhi government's vulnerability assessment do not include HI estimations, which is concerning since even the "low" climate-vulnerable areas in Delhi are at high heatwave risks, the study pointed.

The high intensity of development in Central, East, West, and North-East districts can further elevate the HI risks through heat island formation, it said.

Earlier this month, the India Meteorological Department predicted above-normal maximum temperatures for most parts of the country from April to June, except parts of the northwest and the peninsular regions.

Meanwhile, a report by the McKinsey Global Institute warns that if this continues, by 2030, the country could lose between 2.5 percent to 4.5 percent of its Gross Domestic Product (GDP) per year.

(With PTI inputs)

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