Deadly heat waves will be common in South Asia, even at 1.5 degrees of warming

WASHINGTON–


Residents of South Asia already periodically experience heat waves at the current level of warming. But a new study projecting


the amount of


heat stress residents of the region will experience in the future finds with 2 degrees Celsius of warming,


the population’s


expos


ure


to


heat stress


will nearly triple.

Limiting


warming to 1.5 degrees Celsius will likely reduce that impact by half, but


deadly heat stress will become commonplace


across South Asia


,


according to the



new study



in



Geophysical Research Letters



,


AGU’s journal publishing high-impact, short-format reports with immediate implications spanning all Earth and space sciences.

With



almost one quarter of the world’s population



living in South Asia, the new study underlines the urgency of addressing climate change.

“The future looks bad for South Asia, but


the worst can be avoided by


containing warming to


as low as possible


,” said


Moetasim


Ashfaq, a computational climate scientist at Oak Ridge National Laboratory and co


rresponding


author of the new study. “The need for adaptation over South Asia is today, not in the future. It’s not a choice anymore.”

Earth has warmed by 1 degree Celsius since the start of the Industrial Revolution, according to the



Intergovernmental Panel on Climate Change



. On the current climate trajectory, it may reach 1.5 degrees Celsius of warming in 2040. This deadline leaves little time for South Asian countries to adapt. “Only half a degree


increase from today is going to cause a widespread increase in these events,” Ashfaq said.

A hot region getting hotter

People living in South Asia are especially vulnerable to deadly


heat


waves because the


area


already experiences very hot, humid summers. Much of the population live in


densely populated


cities


without regular access to


air conditioning, and about 60% perform agricultural work and


can’t


escape the heat by staying indoors.

In the new study, the researchers used climate simulations and projections of future population growth to estimate the number of people who will experience dangerous levels of heat stress


in South Asia


at warming levels of 1.5 and 2 degrees Celsius. They estimated the wet bulb temperature


residents will experience


, which is similar to the heat index


, as it


takes into account


humidity


as well as


temperature


.


A


wet bulb temperature of 32 degrees Celsius (89.6 degrees Fahrenheit) is considered to be the point when labor becomes unsafe, and 35 degrees Celsius (95 degrees Fahrenheit) is the limit to human survivability


– when the


body can no longer cool itself.

Their analysis suggests


at 2


degrees of


warming,


the population’s


exposure


to unsafe labor temperatures


will


rise more than two-fold, and


exposure to


lethal temperatures rises 2.7


times,


as


compared to


recent


years


.

Curbing


warming to


1.5


degrees Celsius


w


ill likely


cut that


exposure


in


half


, but


large numbers of people across South Asia will


still


experience


extreme temperatures.


An increase in heat events that create unsafe labor conditions are likely to occur in major crop producing regions in India, such as West Bengal and Uttar Pradesh, and in Pakistan in Punjab and Sindh.


Coastal regions


and


urban centers


such as


Karachi, Kolkata, Mumbai, Hyderabad and Peshawar


are


also


likely to be


heavily


affected


, according to the study


.

“Even at 1.5 degrees, South Asia will have serious consequences in terms of heat stress,” Ashfaq


said.


“That’s why


there is a need to radically alter the current trajectory of greenhouse gas emissions


.”

The results differ from a



similar study conducted in 2017



, which


predicted


that


heat waves


of


lethal temperatures will occur


in South Asia toward the end of the 21


st


century


.


The


researchers


suspect


the earlier study is too conservative, as deadly


heat wave


s have already hit the region in the past. In 2015, large parts of Pakistan and India experienced the



fifth deadliest heat


wave



in the recorded history, which caused about 3


,


500 heat-related deaths.

“A policy framework is very much needed to fight against heat stress and heat wave-related problems,” said T.V. Lakshmi Kumar, an atmospheric scientist at


India’s


SRM Institute of Science and Technology who was not involved in the work. “India has already committed to reduce emissions to combat climate change issues.


”

The study was supported by National Climate?Computing Research Center, which is located within ORNL’s National Center for Computational Sciences and supported under a Strategic Partnership Project between D


epartment of Energy


and National Oceanic and Atmospheric Administration.

###

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?

Notes for Journalists





This research study will be free


ly


available for 30 days.



Download a PDF copy of the paper here


.



N


either the paper nor this pre


ss release is under embargo.

Paper title:





”


Deadly heat stress to become commonplace across South Asia already at 1.5


°C of global warming


”

Authors:






Moetasim Ashfaq,


Oak Ridge National Laboratory, Oak Ridge, Tennessee

Fahad Saeed




,


Climate Analytics, Berlin, Germany

Carl-Friedrich Schleussner



,


Climate Analytics, Berlin, Germany