Damian Carrington Environment editor
Wednesday 2 August 2017 19.00 BST
Extreme heatwaves that kill even healthy people within hours will strike parts of the Indian subcontinent unless global carbon emissions are cut sharply and soon, according to new research.
Even outside of these hotspots, three-quarters of the 1.7bn population – particularly those farming in the Ganges and Indus valleys – will be exposed to a level of humid heat classed as posing “extreme danger” towards the end of the century.
The new analysis assesses the impact of climate change on the deadly combination of heat and humidity, measured as the “wet bulb” temperature (WBT). Once this reaches 35C, the human body cannot cool itself by sweating and even fit people sitting in the shade will die within six hours.
The revelations show the most severe impacts of global warming may strike those nations, such as India, whose carbon emissions are still rising as they lift millions of people out of poverty.
“It presents a dilemma for India between the need to grow economically at a fast pace, consuming fossil fuels, and the need to avoid such potentially lethal impacts,” said Prof Elfatih Eltahir, at Massachusetts Institute of Technology in the US who led the new study. “To India, global climate change is no longer abstract – it is about how to save potentially vulnerable populations.”
Heatwaves are already a major risk in South Asia, with a severe episode in 2015 leading to 3,500 deaths, and India recorded its hottest ever day in 2016 when the temperature in the city of Phalodi, Rajasthan, hit 51C. Another new study this week linked the impact of climate change to the suicides of nearly 60,000 Indian farmers.
Eltahir said poor farmers are most at risk from future humid heatwaves, but have contributed very little to the emissions that drive climate change. The eastern part of China, another populous region where emissions are rising, is also on track for extreme heatwaves and this risk is currently being examined by the scientists.