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Even minor increases in temperatures due to climate change would lead to a dramatic rise in intense heat waves that could see many more people dying during the long Indian summer

The heat in Indian cities has become unbearable in the summers.

The heat in Indian cities has become unbearable in the summers.

A moderate rise in mean temperatures over India is likely to trigger a series of fatal heat waves that could lead to many more deaths in a country where hundreds are already losing their lives due to extreme heat every summer.

The number of deaths has risen rapidly in recent years because of extreme heat in the subcontinent, according to a new study published this month in Science Advances, a peer-reviewed journal. The situation is worsening as global warming results in more frequent heat waves, particularly in tropical countries such as India where millions of people live in dire poverty, which makes them more vulnerable to the effects of climate change, according to a widely cited study in Climate Change, an interdisciplinary journal.

The new study, titled Increasing Probability of Mortality during Indian Heat Waves, says that while India’s average temperatures rose by more than 0.5 degrees Celsius between 1960 and 2009, the probability a massive heat-related mortality event, which the study defines as more than 100 deaths, shot up by as much as 146%.

“It’s getting hotter, and of course more heat waves are going to kill more people,” climatologist Omid Mazdiyasni of the University of California, Irvine, and the lead author of the study, told Associated Press. Mazdiyasni led an international team of scientists who analysed 50 years of data from India Meteorological Department on temperature, heat waves and heat-related mortality. “We knew there was going to be an impact, but we didn’t expect it to be this big,” he said.

The observed increases in temperatures are widespread and strong, the study said. Southern and western India experienced 50% more heat wave events during the period 1985-2009 than during the previous 25-year period. Similarly, heat wave days and the mean duration of heat waves have increased by approximately 25% in most of India. The warming effect is expected to increase summer temperatures that already average between 32 and 36 degrees Celsius, it said.

Temperature and heat wave increases in India between 1960–2009.

Temperature and heat wave increases in India between 1960–2009.

An estimated 25% of India’s 1.2 billion people do not have regular access to electricity, according to the World Bank, which makes them especially vulnerable to heat waves. The new study says that this vulnerability has been made clear by events in recent years. Heat waves in 2010 killed more than 1,300 people in the city of Ahmedabad alone, prompting the start of efforts to develop coordinated heat action plans. See: Readying for an Indian summer

In 2013 and 2015, the country experienced another bout of intense heat waves that killed more than 1,500 and 2,500 people across the country, respectively. Since then, there have been several more deadly heat waves, including the most intense in recorded history in May 2016 when maximum temperatures in Jaisalmer, a desert city in Rajasthan, reached a scalding 52.4°C.

By almost all measures, heat waves have increased markedly across India over the past half-century and, with this, the incidence of heat-related mortality, researchers said. “Our results suggest that even moderate and practically unavoidable increases in mean temperatures, such as 0.5°C, may lead to large increases in heat-related mortality, unless measures are taken to substantially improve the resilience of vulnerable populations,” the study predicted.

“The impact of global climate change is not a spectre on the horizon, it is real, it’s being felt now all over the planet,” study co-author Amir AghaKouchak, Associate Professor of Civil and Environmental Engineering at University of California, Irvine, said in a statement. “It is particularly alarming that the adverse effects are pummelling the world’s most vulnerable populations.”


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