UN report warns of grim repercussions if global warming continues
Experts say that healthy human adults cannot survive if wet-bulb temperatures (TW) exceed 35 degrees Celsius, even in the shade with an unlimited supply of drinking water.
A latest report by the United Nations (UN) has warned of dire consequences for billions if global warming continues unchecked. Earlier climate models suggested it would take nearly another century of unabated carbon pollution to spawn heatwaves exceeding the absolute limit of human tolerance.
But updated projections by Intergovernmental Panel on Climate Change (IPCC) warn of unprecedented killer heatwaves on the near horizon. The IPCC has prepared a 4,000-page report, which will be released in February 2022, news agency AFP reported.
The report said that if the world warms by 1.5 degrees Celsius - 0.4 degrees above today's level - 14% of the population will be exposed to severe heatwaves at least once every five years - "a significant increase in heatwave magnitude". Going up half a degree would add another 1.7 billion people.
Worst hit will be megacities in the developing world that generate additional heat of their own from Karachi to Kinshasa, Manila to Mumbai, Lagos to Manaus, the report said.
It is easier to survive a high temperature day if the air is bone-dry than it is to survive a lower temperature day with very high humidity, according to the report. That steam-bath mix has its own yardstick, known as wet-bulb temperature.
Experts say that healthy human adults cannot survive if wet-bulb temperatures (TW) exceed 35 degrees Celsius, even in the shade with an unlimited supply of drinking water.
"When wet-bulb temperatures are extremely high, there is so much moisture in the air that sweating becomes ineffective at removing the body's excess heat. At some point, perhaps after six or more hours, this will lead to organ failure and death in the absence of access to artificial cooling," said Colin Raymond, lead author of a recent study on heatwaves in the Gulf.