Yahoo – AFP,
August 2, 2017
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| People cool themselves off in a water channel during a heat wave on June 4, 2017 in Lahore, Pakistan (AFP Photo/ARIF ALI) |
South Asia,
home to one-fifth of the world's population, could see humid heat rise to
unsurvivable levels by century's end if nothing is done to halt global warming,
researchers said Wednesday.
The study
in the journal Science Advances warned of "summer heat waves with levels
of heat and humidity that exceed what humans can survive without
protection."
The
research is based on two climate models. One is a "business-as-usual"
scenario in which little is done to contain climate change, and the second is
aimed at limiting temperature rise to well below two degrees Celsius, as
pledged by more than 190 nations under the 2015 Paris climate accord.
The study
is the first of its kind to look not just at temperatures, but at the forecast
of "wet-bulb temperature," which combines temperature, humidity and
the human body's ability to cool down in response.
The
survivability threshold is considered to be 35 degrees Celsius, or 95 degrees
Fahrenheit.
Under a
business-as-usual scenario, "wet-bulb temperatures are projected to
approach the survivability threshold over most of South Asia, and exceed it at
a few locations, by the end of the century," said the report.
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.
The densely
populated farming regions of South Asia could fare the worst, because workers
are exposed to heat with little opportunity for escape into air-conditioned
environments.
"Deadly
heat waves could begin within as little as a few decades to strike regions of
India, Pakistan, and Bangladesh, including the fertile Indus and Ganges river
basins that produce much of the region's food supply," said the report.
Indian is
home to 1.25 billion people, while another 350 million live in Bangladesh and
Pakistan.
Already in
2015, the fifth deadliest heat wave in modern history swept over large parts of
India and Pakistan, killing some 3,500 people.
But
researchers said their models gave cause for hope, too. Under the scenario in
which steps are taken to limit warming over the coming decades, the population
exposed to harmful wet-bulb temperatures would increase from zero to just two
percent.
Temperatures
would still reach dangerous levels (over 31 Celsius), but would not be quite so
close to the fatal threshold.
"There
is value in mitigation, as far as public health and reducing heat waves,"
said lead author Elfatih Eltahirhe, professor of environmental engineering at
the Massachusetts Institute of Technology (MIT).
"With
mitigation, we hope we will be able to avoid these severe projections. This
is not something that is unavoidable."
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