Irshad Salim — South Asia is a region of deep poverty where one-fifth of the world’s population live, with almost 9 out of 10 people being under the age of 30 — it also has a huge youth bulge with promising economic indicators going forward.
However, new research suggests that by the end of this century climate change could lead to summer heat waves in South Asia with levels of heat and humidity that exceed what humans can survive without protection. Many are dependent on subsistence farming that requires long hours of hard outdoor labor.
“That makes them very vulnerable to these climatic changes,” said MIT professor of environmental engineering Elfatih Eltahir, one of the co-authors of the study.
Under business-as-usual scenarios, without significant reductions in carbon emissions, the study shows these 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 — the summer of 2015 produced one of the deadliest heat waves in history in the region, killing an estimated 3,500 people in Pakistan and India over a few months.
“That was only the tip of the iceberg,” Eltahir said. “In the sense that much more severe heat waves are coming.”
About 15 per cent of the South Asian population gets exposed to those extreme temperatures of 31 or 32 C, but under the business-as-usual model that number would reach 75 per cent by 2100, the study found. Four per cent of that population would see wet bulb temperatures of 35 C.
“This is a new territory we’re moving into,” Eltahir said.
But there is still time to avert such severe warming if measures are implemented now to reduce the most dire consequences of global warming, says Eltahir.
Carbon emissions cuts as pledged under the 2015 Paris Climate Agreement dramatically reduces the risk to the region, said Eltahir.
“Emission cuts will make a big difference in the lives of the most vulnerable people in the region. This is not an abstract concept.”
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 Eltahir.
The study follows an earlier report that looked at projected heat waves in the Persian Gulf region. While the number of extreme-heat days projected for that region was even worse than for South Asia, the report says the impact in the latter area could be vastly more severe.
While the Persian Gulf area has a relatively small, relatively wealthy population and little agricultural land, the areas likely to be hardest hit is northern India, Bangladesh, and southern Pakistan which are home to 1.5 billion people and have the largest agricultural belt in the region.
These areas in South Asia are also among the poorest in the region, with much of the population dependent on subsistence farming that requires long hours of hard labor out in the open and unprotected from the sun.
That makes them very vulnerable to these climatic changes, assuming no mitigation, says Eltahir.
While the projections show the Persian Gulf may become the region of the worst heat waves on the planet, northern India is a close second, and eastern China, also densely populated, is third.
India and China also remain two countries where emission rates of greenhouse gases continue to rise, driven mostly by economic growth. These results pose a dilemma for countries in the region, like India, Pakistan and Bangladesh.
Global warming is not just a global problem — for them, they will have some of the hottest spots on the planet. In fact, a separate study by researchers at the University of California at Irvine and elsewhere, published recently also in Scientific Advances, reached similar conclusions based on a different kind of analysis using recent weather records.
According to this study, by 2100 exposure to 32-degree wet-bulb temperatures by South Asians will increase to about 70 percent of the population, and about 2 percent of the people will sometimes be exposed to the survivability limit of 35 degrees. And because the region is important agriculturally, it’s not just those directly affected by the heat who will suffer, Eltahir says: “With the disruption to the agricultural production, it doesn’t need to be the heat wave itself that kills people. Production will go down, so potentially everyone will suffer.”
But while the study provides a grim warning about what could happen, it is far from inevitable, Eltahir stresses.
The study examined not just the “business as usual” case but also the effects under a moderate mitigation scenario, which showed that these dramatic, deadly effects can still be averted.
“There is value in mitigation, as far as public health and reducing heat waves,” Eltahir says. “With mitigation, we hope we will be able to avoid these severe projections. This is not something that is unavoidable.”
“This study provides vitally important information for planning for a hot, wet future in South Asia,” says Matthew Huber, a professor of earth, atmospheric, and planetary sciences at Purdue University.
“The results are impressive and, frankly, oppressive,” he says. “The study shows that unfettered warming is likely to do substantial harm to the health and well-being of the most populous democracy on Earth. This is very bad news.”