Sunday, 23 September, 2018

It's the humidity: killer heat waves projected for much of south Asia

Indian women walk home after collecting drinking water from a well at Mengal Pada in Thane district in Maharashtra state India. A new study suggests wide swaths of northern India It's the humidity: killer heat waves projected for much of south Asia
Melinda Barton | 04 August, 2017, 05:51

In 2015, the region experienced a deadly heat wave that killed roughly 3,500 people in Pakistan and India over a few months.

After running high-resolution simulations under two climate scenarios, Eun-Soon Im and colleagues reveal wet-bulb temperatures are projected to approach the survivability threshold (35 degrees Celsius) over most of South Asia, and exceed it at a few locations, by the end of the century under a business-as-usual (BAU) scenario, while reaching unsafe levels (over 31 Celsius) under a mitigation scenario (roughly comparable to the goals pledged by the 2015 UN Conference on Climate Change).

The hot and humid temperatures in the Indo-Gangetic Plains (IGP), home to over 900 million people, would exceed the upper limit of what normally people can tolerate, leading to higher mortalities due to heat waves, said a team of researchers led by Elfatih Eltahir, a professor of climate and hydrology at the MA of Institute of Technology (MIT) in the US.

The Guardian reported that around 1.7 billion people live in the southern part of Asia, and if the emission of carbon would not be reduced then extreme heat waves could affect the Indian subcontinent.

The new findings, based on detailed computer simulations using the best available global circulation models, are described this week in the journal Science Advances, in a paper by Elfatih Eltahir, a professor of civil and environmental engineering at MIT; Eun Soon Im, a former researcher at the Singapore-MIT Alliance for Research and Technology and now a professor at the Hong Kong University of Science and Technology; and Jeremy Pal, a professor at Loyola Marymount University in Los Angeles.

Human beings can survive a wet-bulb temperature of up to 35 degrees Celsius.

A fifth of the world's population could be forced to migrate from Asia due to climate change by the end of the century, scientists have warned.

Wet-temperature bulb can be problematic upon exposure to humans, as exposure "of around 35 degrees Celsius (95 degrees Fahrenheit) for even a few hours will result in death even for the fittest of humans under shaded, well-ventilated conditions". Some 25 per cent of India's population still has no access to electricity.

"That was only the tip of the iceberg", Eltahir said.

But, the impact would be worse in South Asia.

About 30 percent of the population in the region would be exposed to these harmful temperatures, up from zero percent at present, said the report. People lie sprawled atop woven cots for hours a day, moving as little as possible as they wait out the heat. The scientists also noticed that eastern China is also getting extreme heat waves, according to the Deutsche Welle. Mostly, farmers who work near the Indus valley and the Ganges could be affected by the deadly heat waves.

India recorded 123.8 degrees Fahrenheit in Rajasthan, in 2016, which was the hottest temperature. Dozens of cities have signed on, while weather forecasts have been expanded to include new areas and longer-term projections.