(CN) — In the latest bleak news from climate science, a Wednesday report in the journal Science Advances finds that South Asia will be exposed to extreme temperatures that will approach or exceed the upper limit of human survivability before 2100.
How often the region, which is home to one-fifth of the global population, experiences these deadly conditions will depend on the progress nations make in curbing greenhouse gas emissions, scientists reported.
The study evaluated how such climate change-induced temperature extremes will materialize under two scenarios: a “business-as-usual” model, meaning current greenhouse gas emissions levels continue; or one in which manmade pollutants are mitigated, comparable to the goals established by the 2016 Paris agreement.
The treaty aims to keep global average temperatures below 3.6 degrees Fahrenheit above pre-industrial levels and pursue efforts to keep warming under 2.7 degrees Fahrenheit.
To determine how these conditions would affect human health, the team forecast the region’s possible wet bulb temperatures, which measure heat, humidity and the human body’s ability to cool down in response.
South Asia is particularly at risk to heat waves due to the combination of monsoons that transport hot and humid air into the Ganges and Indus valleys from the Bay of Bengal and the Arabian Sea; elevations in valleys that are close to sea level, resulting in generally warmer temperatures, compared to higher elevations; and irrigation that tends to increase wet bulb temperatures near the irrigated areas.
Under the first climate scenario, the team found that wet bulb temperatures are projected to approach the survivability threshold, 95 degrees Fahrenheit, and exceed it in certain locations by the end of the century. About 30 percent of the population of South Asia would be exposed to harmful wet bulb temperatures in this situation. No inhabitants of the region are yet exposed to such conditions.
“If climate change remains unabated, parts of South Asia will become uninhabitable without air conditioning during extreme years,” study co-author Jeremy Pal, a professor of civil engineering and environmental science at Loyola Marymount University in Los Angeles said in an email to Courthouse News. “Not even the fittest of humans would be able to survive even in well-ventilated shaded conditions.”
Under the mitigated scenario, wet bulb temperatures will reach dangerous levels: over 87.8 degrees Fahrenheit. About 2 percent of the region’s population would be exposed to harmful wet bulb temperatures, which highlights the significant impact of climate change mitigation efforts, according to the team.
“For example, we show that there are no exceedances of the 35 degrees Celsius (95 degrees Fahrenheit) threshold if we hold emissions to mitigation levels slightly less severe than what is ultimately required by the Paris agreement,” Pal said.
Certain populations would still be vulnerable to wet bulb temperatures, including older people, and people who work outdoors and have poor access to air-conditioning.
The researchers noted that some of the poorest regions on Earth, which produce significantly less greenhouse gas emissions than richer nations, will suffer the most from manmade climate change.
“Affluent regions, such as the United States and Europe, have the financial means to adapt to these adverse consequences of climate change; however, poorer regions, where approximately 80 percent of the world’s population resides, do not necessarily have the capacity to adapt,” Pal said. “This is particularly unjust because per capita greenhouse gas emissions in most of these poorer regions are less than a tenth of those in industrialized nations.
“Populations in the West should be aware that climate change is a global issue.”
Pal added that these nations, and others, such as China, are growing in population and economically, and their total and per capita emissions are increasing.
“Countries in South Asia are put in a difficult situation of balancing economic and population growth and protecting its populations from the negative impacts of climate change,” Pal said.
Increasing wet bulb temperatures could also spur emigration, as residents flee such harsh conditions, according to Pal.
“We might start to see large migrations and climate refugees,” he said.
Despite the alarming projections, the team says there is still time to adjust the region’s climate path, which can be aided by mitigation plans and growing public awareness.
“The study also suggests that if we are to comply with emissions rates implied by the Paris agreement, we can significantly reduce the extreme consequences of climate change,” Pal said. “(I)t is not all doom and gloom.”
President Donald Trump decided this summer to withdraw the United States from the Paris Accord.