India underestimating heatwave impact, more than 90% of the country at risk: Study

Climate experts and policymakers should re-evaluate the metrics for assessing the country's climate vulnerability as heatwaves in India;and the Indian subcontinent become recurrent and long-lasting
India should accelerate the heat action plans and start identifying high heat vulnerability zones at the district level. Representative photo: iStock.
India should accelerate the heat action plans and start identifying high heat vulnerability zones at the district level. Representative photo: iStock.

India has been underestimating the impact of heatwaves on its development. More than 90 per cent of the country is at risk of suffering losses in livelihood capacity, food grains yields, vector-borne disease spread and urban sustainability, according to a new study by the University of Cambridge.

The study published in PLOS Climate on April 20, 2023 pointed out that the Indian government made a much lower estimate — that only 20 per cent of the country is vulnerable to climate impacts.

The government’s estimate is from the National Climate Vulnerability Index (CVI), developed by the Department of Science and Technology.

CVI is a composite index that uses various indicators to evaluate climate impact on India’s socio-economic features and livelihood, biophysical, institutional and infrastructural characteristics.

“CVI is a robust metric. But it underestimates the vulnerability from heatwaves as it does not include any physical risk factors from extreme heat,” Ramit Debnath from the University of Cambridge told Down To Earth.

Global mean surface temperature rise would affect all 17 Sustainable Development Goals (SDG), according to the World Meteorological Organization.

This is especially concerning as India is yet to achieve its developmental goals, despite recent strides in its self-reported SDG India Index, the researchers wrote in their report.

Climate experts and policymakers should re-evaluate the metrics for assessing the country’s climate vulnerability as heatwaves in India and the Indian subcontinent become recurrent and long-lasting, they added.

Debnath and his colleagues evaluated India’s vulnerability by combining CVI and Heat Index (HI), using the 2022 heatwaves across India as a case study.

HI is what the temperature feels like to the human body when relative humidity is combined with the air temperature, according to the National Weather Service.

“CVI and HI are non-comparable, it’s like apples and oranges. But what we show is that CVI and HI can provide a better understanding of heatwave impacts,” Debnath noted.

Their analysis put West Bengal and Andhra Pradesh in the ‘extreme danger’ category. A region is placed in extreme danger on the heat index if the temperature is above 51 degrees Celsius or higher, according to the HI.

But, according to CVI, West Bengal is not vulnerable. “West Bengal scores high in socio-economic, biophysical, livelihood, institutional and infrastructural characteristics. Thus, the CVI scores were lower,” Debnath added.

More than 90 per cent of the country, according to the HI estimate, falls in the ‘extremely cautious’ (32-40°C) or ‘danger’ (40-51°C) category.

Meghalaya and Ladakh were placed in the cautious (26-32°C) category and Sikkim was in low risk.

They also specifically studied Delhi to evaluate its HI and impact on the national capital’s urban sustainability. Their analysis showed that 100 per cent of the city faces ‘danger’ levels.

The Delhi government’s assessment, on the other hand, shows that south and northeast Delhi are most vulnerable to climate change impacts.

Debnath said India should accelerate the heat action plans and start identifying high heat vulnerability zones at the district level. 

“This data is missing currently. Once we have better and robust measure of heatwave impacts, we can have a strong financial mechanism to mitigate and adapt to such extreme weather events,” he said.

Climate financing, he said, can also strengthen the existing technologies and socio-economic heat adaptation mechanisms. For example, it can help secure cooling energy for all, water and shelter infrastructure, he added.

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