Two new scientific studies have linked a warming climate to human mortality on the Indian subcontinent, warning that droughts, hotspots and humid heatwaves will kill people or push them into suicide.
The conclusions of these studies are stark. As many as 59,000 suicides in India over the last three decades can be attributed to climate change. And unless global carbon emissions are curbed, at least four per cent of India’s population will face near-fatal six-hour heatwaves at least once between the years 2071-2100.
The US studies — one conducted by scientists at the Massachussets Institute of Technology and the other by researchers at the University of California Berkeley - were published on August 2 and July 31 respectively, in the journals Science Advances and the Proceedings of the National Academy of Sciences.
The MIT study uses computer simulations to model the effect of heatwaves in northern India, which already faces severe summers. The team of scientists, led by Elfatih Eltahir, an environmental engineering professor, predicted similarly fatal heatwaves in the Arabian Gulf in a study published two years ago.
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The impact of these heatwaves is likely to be more forceful in India, with its larger and denser population and its high levels of poverty. Two years ago, a heatwave killed 3,500 people across India and Pakistan. Last year, India recorded its hottest-ever day, measuring a temperature of 51°C in the town of Phalodi, in the northern state of Rajasthan.
Dr Eltahir’s study focuses on a concept known as “wet-bulb temperature”, which represents a combination of humidity and heat. Human beings are unable to cool themselves through perspiration once wet-bulb temperatures reach 35°C.
Exposure to such temperatures “for even a few hours will result in death even for the fittest of humans under shaded, well-ventilated conditions”, the MIT paper reported.
In a “business as usual” scenario, with no cuts being made to emissions, several regions across central and northern India, as well as Bangladesh, will reach these fatal temperatures by the end of this century. These include the Indian cities like Lucknow and Patna, which have a total population of more than 5 million people.
The humidity will be made worse by the monsoon, which annually transports masses of warm, rain-bearing air to the Indian subcontinent.
With “moderate mitigation” in emissions — a situation in which global average temperatures rise by only 2.25°C — India will escape wet-bulb temperatures of 35°C. But “vast regions of South Asia are projected to experience episodes exceeding 31°C, which is considered extremely dangerous for most humans,” the paper said.
At Berkeley, a researcher named Tamma Carleton, who is a doctoral candidate in agricultural economics, analysed 47 years of suicide records and climate data.
Since 1980, suicide rates in India have nearly doubled, and more than 130,000 Indians kill themselves every year.
Thousands of these suicides involve farmers who have sunk into debt and witnessed their harvests suffer due to droughts. In May, the state of Maharashtra alone reported that 852 of its farmers had committed suicide in the first four months of this year.
Last year, Maharashtra had declared drought conditions in at least 29,000 of its 43,665 villages.
According to government statistics, more than 12,000 farmers have killed themselves every year since 2013. Roughly 300,000 farmers have committed suicide since 1995, when the government first started to keep detailed records of these deaths.
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Ms Carleton’s study of data from 32 Indian states found a correlation between temperature spikes and suicides.
“For temperatures above 20°C, a 1°C increase in a single day’s temperature causes [roughly] 70 suicides, on average,” she wrote. “This effect occurs only during India’s agricultural growing season, when heat also lowers crop yields.”
The season runs from June to September, when farmers have sown their crops and wait expectantly for rain to determine their productivity.
More than 59,000 of India’s suicides since 1980 can be attributed directly to warming caused by human activity, Ms Carleton concluded. The number represents nearly 7 per cent of India’s suicides over the last 37 years.
Similarly, a rise in rainfall of even a centimetre each year corresponded to a 7 per cent drop in the rate of suicides.
“Without interventions that help families adapt to a warmer climate, it’s likely we will see a rising number of lives lost to suicide as climate change worsens in India,” Ms Carleton said.
“The tragedy is unfolding today. This is not a problem for future generations. This is our problem, right now.”