Climate Change Worst Case Scenario

On March 24, 2010 a paper entitled An Adaptability Limit To Climate Change Due To Heat Stress was approved for publication in the Proceedings of the National Academy of Science, authored by Steven C. Sherwood, and Matthew Huber. It is amongst the most ominous scientific papers ever published.

With climatologists it is common to quantify the sensitivity of the planetary climate with respect to global average temperature. According to the National Center for Atmospheric Research (NCAR):

...the average annual temperature for the globe between 1951 and 1980 was around 57.2°F (14°C). In 2015, the hottest year on record (at that time), the temperature was about 1.8°F (1° C) warmer than the 1951–1980 base period.

The climate sensitivity due to Carbon-dioxide is often expressed as the temperature change in °C associated with a doubling of the concentration of carbon dioxide in Earth's atmosphere. Indeed this was the measure chosen by Svante Arrhenius in his 1896 paper On the Influence of Carbonic Acid in the Air Upon the Temperature of the Ground published in the Philosophical Magazine and Journal of Science. Estimates from paleoclimatological data predict a sensitivity of 3 °C. Modeling studies indicate similar results.



https://en.wikipedia.org/wiki/Svante_Arrhenius#Greenhouse_effect

The purpose of the Sherwood & Huber paper was to look at the physiological limits of adaptation, and to see if humanity could warm the planet to such a degree that those limits would be exceeded and if so for what percentage of the Earth's surface.

To exceed the physiological limits of a human beings ability to tolerate heat, means dying.

The author's research indicates that at wet bulb temperatures of 35°C you will die within hours.

Wet Bulb Temperature is a measuring method. Traditionally it means placing a tight wet sock over the bulb of a conventional thermometer and whirling the apparatus. At low humidity a substantial drop in temperature will occur. At 100% humidity dry bulb and wet bulb temperatures are identical.

Presently maximum wet bulb temperatures are in the range of 26°C to 27°C for the entire planet.

There is no place (given shade, good health, and adequate water) that is not survivable because of heat on the surface of our planet. (Some exceptions, such as the caldera of an active volcano, exist.)

The conclusion of the paper is that if we were to burn all those fossil fuels which we could extract, it may be possible to render the parts of the planet uninhabitable.

We conclude that a global-mean warming of roughly 7 °C would create small zones where metabolic heat dissipation would for the first time become impossible, calling into question their suitability for human habitation. A warming of 11–12 °C would expand these zones to encompass most of today’s human population. This likely overestimates what could practically be tolerated: Our limit applies to a person out of the sun, in gale-force winds,doused with water, wearing no clothing, and not working...

The authors note that:

A global-mean warming of only 3–4 °C would in some locations halve the margin of safety ... that now leaves room for additional burdens or limitations to cooling. Considering the impacts of heat stress that occur already, this would certainly be unpleasant and costly if not debilitating.

And they warn that:

If warmings of 10 °C were really to occur in next three centuries, the area of land likely rendered uninhabitable by heat stress would dwarf that affected by rising sea level. Heat stress thus deserves more attention as a climate-change impact.

My own conclusion is that the complete and permanent destruction of modern civilization, and possibly the end of human life by means of climate change are achievable if we choose to continue on our current path.

Link: http://www.pnas.org/content/107/21/9552.full

Edited 9/2/2017 06:10:41