India, Pakistan, Bangladesh and other parts of South Asia may experience heat waves, in which people cannot survive, by the end of this century if nothing is done to curb global warming, says a new study. About 30% of the population in the South Asia would be exposed to high temperature coupled with rising humidity.

The study, which was published in the journal Science Advances on Wednesday, warned of “summer heat waves with levels of heat and humidity that exceed what humans can survive without protection”.

Researchers have come up with a “wet bulb temperature” that combines temperature, humidity and the human body’s ability to cool down. A wet bulb temperature of 35°C is considered the upper limit for human survival. The wet bulb temperatures on earth have rarely exceeded 31°C, reported BBC. Only once, in Iran in 2015, during a deadly heat wave, the wet bulb temperature was close to 35°C.

If the UN Paris accord is not followed...

The study takes into account two climate models. One is a “business-as-usual” scenario in which nothing is done to curb global warming, and the other is if steps are taken as per the 2015 Paris climate accord.

If no measures are taken to reduce greenhouse emissions, the densely-populated farming areas of South Asia will be affected the most by this heat and humidity. “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.

However, the results could change if steps are taken to limit affects of global warming. Researchers said that if the Paris climate accord is followed, only 2% population will be exposed to harmful wet bulb temperatures. But, temperatures will still go over 31°C, according to the study.