90% of India vulnerable to heatwave impact, says study

“The heatwaves in India and the Indian subcontinent become recurrent and long-lasting, it is high time that climate experts and policymakers reevaluate the metrics for assessing the country’s climate vulnerability,” the researchers said.

College students cover themselves in clothes to protect themselves from the Sun as they move on the road in the sweltering heat in Bhubaneswar. | Photo Credit: Biswaranjan Rout

Nearly 90% of India is in a “danger zone” from heatwave impact and almost all of Delhi is at the risk of severe heatwave impacts, which is not reflected in its recent state action plan for climate change, says a study published on April 19 in the peer-reviewed PLOS Climate.

On April 16, 13 people attending a public function died of heat stroke in Navi Mumbai, Maharashtra. While February and March saw record-setting temperatures, deaths have been reported even when the temperatures were not sky-rocketing and people were exposed to extreme humidity.

A heatwave is defined as a period of unusually hot weather with above-normal temperatures that typically last three or more days.

In India, heatwaves are generally experienced during the March-June period and on average, two or three heatwave event occur every season.

Heatwaves are predominantly observed over two areas — central and northwest India and coastal Andhra Pradesh and Odisha. Climate change and global warming, current research suggests, have increased the probability of heatwaves in the past three decades.

The study, by Ramit Debnath at the University of Cambridge, United Kingdom and colleagues, also suggested that heatwaves, made more likely by climate change, may impede India’s progress toward achieving its Sustainable Development Goals (SDG).

India has committed to achieving 17 United Nations Sustainable Development Goals (SDG) such as eliminating poverty, promoting good health and well-being, and decent work and economic growth.

In order to analyse India’s climate vulnerability, and how climate change may impact SDG progress, the scientists compared India’s heat index (HI) with its climate vulnerability index, (CVI), a composite index using various indicators to account for socioeconomic, livelihood, and biophysical factors.

They accessed a publicly available dataset on State-level climate vulnerability indicators from the Centre’s National Data & Analytics Platform to classify severity categories.

The researchers then compared India’s progress in SDG over 20 years (2001-2021) with extreme weather-related mortality from 2001-2021. They found that heatwaves have weakened SDG progress more than previously estimated and that current assessment metrics didn’t fully capture the nuances of India’s vulnerabilities to heat waves.

“This study shows that heatwaves make more Indian States vulnerable to climate change than previously estimated with the CVI. The heatwaves in India and the Indian subcontinent become recurrent and long-lasting, it is high time that climate experts and policymakers reevaluate the metrics for assessing the country’s climate vulnerability,” the researchers said in a statement.