The study highlights mounting pressure on governments, cities and public health systems across South Asia to adapt to increasingly dangerous heat conditions.
Extreme heat is no longer an occasional disaster in South Asia. According to a new scientific study, deadly heatwaves that once would have been considered rare are now becoming a recurring reality across India and Pakistan as human-driven climate change intensifies.
Researchers from World Weather Attribution found that a severe heatwave that swept through the region in late April and early May was made significantly more likely because of global warming caused by greenhouse gas emissions.
The study analyzed historical observational data alongside climate model simulations to measure the influence of human-induced warming on the event, which pushed temperatures above 46 degrees Celsius in several cities.
The heatwave killed at least 37 people in India and 10 people in Karachi, Pakistan’s largest city.
Scientists now say heat events on that scale are approximately three times more likely to occur than they were in the pre-industrial climate era.
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Deadly Heatwaves Now Expected Every Five Years
Researchers concluded that heatwaves of similar intensity are now expected roughly once every five years in the region.
That shift reflects how rapidly climate change is altering weather extremes across South Asia, where already hot conditions are becoming increasingly dangerous.
“What was once considered an extreme event is now becoming a regular reality,” said Mariam Zachariah, one of the researchers involved in the study and a specialist in extreme weather and climate change at Imperial College London.
“Temperatures are being pushed to dangerous levels, making life-threatening conditions more common for hundreds of millions in India and Pakistan,” she said.
The findings add to growing concerns among scientists that climate-driven heatwaves are emerging as one of the most immediate and deadly environmental threats facing densely populated countries.
Heat Poses Serious Health Risks for Millions
Extreme heat is particularly dangerous because it disrupts the body’s natural cooling mechanisms, increasing the risk of heatstroke and other heat-related illnesses.
Without rapid treatment, those conditions can become fatal.
The risks are especially severe for vulnerable populations, including older adults, children, people with disabilities, unhoused communities and incarcerated individuals.
Outdoor workers such as construction laborers and street cleaners are also among the most exposed groups.
According to the International Labour Organization, more than 70 per cent of the global workforce — around 2.4 billion people — are now at high risk from extreme heat exposure.
The organization estimates that as many as 19,000 workers die each year from heat-related illnesses.
In South Asia, poverty and limited access to cooling systems often intensify those dangers.
Researchers noted that both urban and rural poor communities face disproportionate exposure because of informal housing conditions and limited protection from rising temperatures.
Human-Caused Warming Is Making Heatwaves Longer and More Intense
Scientists say the increase in extreme heat is directly linked to the warming of the planet caused by greenhouse gases trapping heat in the atmosphere.
That process raises Earth’s surface temperature and contributes to longer, hotter and more frequent heatwaves worldwide.
According to the study, every heatwave currently occurring on Earth is now stronger and more likely because of climate change caused by human activity.
In South Asia, the pre-monsoon season is becoming hotter and extending for longer periods.
The World Weather Attribution analysis found that the recent India-Pakistan heatwave would have been approximately 1 degree Celsius cooler in a pre-industrial climate.
While a 1-degree increase may appear small in everyday terms, scientists stress that such warming represents a major increase in atmospheric energy at a planetary scale.
That seemingly small temperature shift fundamentally changes the probability of extreme events, pushing previously rare heatwaves into far more common occurrence.
Rising Humidity Is Turning Heat Into a Lethal Threat
Researchers also warned that rising humidity levels are amplifying the dangers associated with extreme heat across South Asia.
For every 1-degree Celsius increase in atmospheric temperature, air can hold around 7 per cent more moisture.
In countries such as India and Pakistan, where heat is often accompanied by high humidity, that combination can push conditions beyond the limits of human tolerance.
Scientists say the added moisture makes it harder for the human body to cool itself through sweating, increasing the likelihood of deadly heat stress.
A heatwave that may once have been survivable can therefore become a severe public health crisis under hotter and more humid conditions.
South Asia Faces Growing Pressure to Adapt
The study highlights mounting pressure on governments, cities and public health systems across South Asia to adapt to increasingly dangerous heat conditions.
As climate change accelerates, scientists warn that extreme heat is likely to become one of the defining challenges for the region’s future, affecting public health, labor productivity, infrastructure and economic stability.
Researchers say the findings underscore the urgent need for stronger climate adaptation strategies, improved heat warning systems and protections for vulnerable communities and outdoor workers.
With temperatures continuing to rise globally, scientists caution that extreme heat events once considered exceptional may increasingly become part of everyday life for hundreds of millions of people across South Asia.
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