A new study led by IIT Gandhinagar reveals that heat-related health risks, previously considered mainly a summer threat, are increasingly becoming a concern during India's monsoon season due to rising Uncompensable Heat Stress (UHS), a condition where the body struggles to cool down from extreme heat and humidity. Analyzing 1979-2021 data, the study found a significant increase in UHS area and frequency, with projections indicating that under a 2°C warming scenario, monsoon UHS could affect 58% of India, comparable to the 60% projected for summer, particularly impacting the Indo-Gangetic plain, north-western India, and eastern coastal regions. This expansion of UHS poses a substantial threat to public health, climate resilience, and labor productivity, especially in rural areas where access to cooling facilities is limited and where a majority of India's population resides, while urban populations also face risks from the urban heat island effect, underscoring the critical need to limit global warming and implement effective climate adaptation strategies.

A new study led by IIT Gandhinagar reveals that heat-related health risks, previously considered mainly a summer threat, are increasingly becoming a concern during India's monsoon season due to rising Uncompensable Heat Stress (UHS), a condition where the body struggles to cool down from extreme heat and humidity. Analyzing 1979-2021 data, the study found a significant increase in UHS area and frequency, with projections indicating that under a 2°C warming scenario, monsoon UHS could affect 58% of India, comparable to the 60% projected for summer, particularly impacting the Indo-Gangetic plain, north-western India, and eastern coastal regions. This expansion of UHS poses a substantial threat to public health, climate resilience, and labor productivity, especially in rural areas where access to cooling facilities is limited and where a majority of India's population resides, while urban populations also face risks from the urban heat island effect, underscoring the critical need to limit global warming and implement effective climate adaptation strategies.

A new study led by IIT Gandhinagar reveals that heat-related health risks, previously considered mainly a summer threat, are increasingly becoming a concern during India's monsoon season due to rising Uncompensable Heat Stress (UHS), a condition where the body struggles to cool down from extreme heat and humidity. Analyzing 1979-2021 data, the study found a significant increase in UHS area and frequency, with projections indicating that under a 2°C warming scenario, monsoon UHS could affect 58% of India, comparable to the 60% projected for summer, particularly impacting the Indo-Gangetic plain, north-western India, and eastern coastal regions. This expansion of UHS poses a substantial threat to public health, climate resilience, and labor productivity, especially in rural areas where access to cooling facilities is limited and where a majority of India's population resides, while urban populations also face risks from the urban heat island effect, underscoring the critical need to limit global warming and implement effective climate adaptation strategies.

What was once considered primarily a summer threat,  heat-related health risks, may now become a serious concern during monsoon season as well, a new study suggests. While heat burden in India has largely been a dry summer phenomenon, the country is entering a new phase in which the hot, humid monsoon is becoming just as dangerous.

The study, led by the Indian Institute of Technology (IIT) Gandhinagar, analysed 1979-2021 data and found that Uncompensable Heat Stress (UHS) increased considerably in both area and frequency.

UHS is a physiological threshold beyond which the body struggles to cool down due to extreme heat and humidity.

Rise in monsoon heat stress

Presently, heat stress is primarily a summer phenomenon, affecting 8 per cent of India, against 1 per cent during monsoons. This is now set to change.

Under a 2°C warming relative to pre-industrial levels, monsoon UHS (July-September) is expected to expand to 58 per cent of India. This will be almost equal to 60 per cent during the summer (April-June). Critical areas include the Indo-Gangetic plain, north-western India, and parts of eastern coastal India.

Health risks

Notably, summer UHS is strongly linked to heat-related deaths. Between 1992 and 2020, heatwaves caused a staggering 25,000 deaths. Now with the rise in monsoon UHS, it will further pose a risk to health, climate resilience and labour productivity, especially in vulnerable and populous regions.

“We emphasise the critical need to limit global warming to 1.5°C and reduce vulnerability to UHS in India, particularly in the context of a growing population and rapid urbanisation,” the researchers noted.

India is undergoing population expansion along with a rise in urbanisation.

“However, about 68 per cent of the population in India currently resides in rural areas, where facilities such as air conditioning are often unavailable to mitigate the effects of UHS,” they noted. Among the three worst-affected regions, the share of rural population exceeds 75 per cent in the northwestern and Indo-Gangetic plains and is over 65 per cent in the eastern coastal regions.

While rural areas suffer from a lack of artificial cooling, urban populations, despite access to cooling facilities, can face the urban heat island. The urban heat island effect is when cities experience higher temperatures than their surrounding rural areas.

“Our findings have implications for public health, urban planning, and climate adaptation efforts in India, allowing policymakers and stakeholders to effectively prioritise resources and interventions amidst the challenge of reducing vulnerability,” the researchers have noted.

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