"Heat Waves Creeping Toward Deadly Heat-Humidity Threshold"

"As global temperatures rise, river valleys in South Asia will face the highest risk of heat waves that reach the limits of human survivability, a new study shows."

"If global warming continues on its current pace, heat waves in South Asia will begin to create conditions so hot and humid that humans cannot survive outdoors for long, a new study shows. The deadly heat would threaten millions of vulnerable people in some of the world's most densely populated regions in India, Pakistan and Bangladesh—low-lying river valleys that produce most of the region's food.

About 1.5 billion people live in the crescent-shaped region identified as the highest-risk area in a new study by scientists from the Massachusetts Institute of Technology and Loyola Marymount University in Los Angeles. The researchers combined global and detailed regional climate models to show where the most extreme conditions are expected by the end of this century.

The researchers focused on a key human survivability threshold first identified in a 2010 study, when U.S. and Australian researchers showed there is an upper limit to humans' capacity to adapt to global warming. That limit is expressed as a wet-bulb temperature, which measures the combination of heat and humidity for an index of physical human misery. When the wet-bulb temperature goes above 35 degrees Celsius, the body can't cool itself and humans can only survive for a few hours, the exact length of time being determined by individual physiology."

Bob Berwyn reports for InsideClimate News August 2, 2017.