This map shows the maximum wet-bulb temperatures reached in a climate model from a high carbon dioxide emissions future climate scenario with a global-mean temperature 12 degrees Celsius warmer than 2007. The white land areas exceed the wet-bulb limit at which researchers calculated humans would experience a potentially lethal level of heat stress. Credit: Purdue University graphic/Matthew Huber
Global warming of 12°C would make most areas of the world uninhabitable, and burning all the fossil fuels on the planet could get us to this level. That’s what Steven Sherwood of the University of New South Wales, Australia, and Matthew Huber of Purdue University, USA, claim.
Writing in a paper published online in the Proceedings of the National Academy of Science this week, the scientists examine the heat stress that humans and mammals can bear. This is assessed through a measure known as wet bulb temperature, which combines the effect of heat and humidity. The world’s hottest areas normally have low humidity, referred to as “dry heat”, Huber explained. “When it is dry, we are able to cool our bodies through perspiration and can remain fairly comfortable,” he said.
They say that currently wet bulb temperatures on the planet never exceed 31°C, while humans and other mammals would die if exposed to levels above 35°C for extended periods. They predict that conventional temperature rises of 7°C would begin to see wet bulb temperatures above 35°C in some regions, while 11-12°C rises would force humans out of most areas where they currently live . Read the rest of this entry »
