Simmered to the Edge of the World

[Lord Beria3]

http://www.sublimeoblivion.com/2010/05/ ... the-world/

When denier ideologues make the transition to accepting the reality of anthropogenic global warming, one of the arguments they start to use tends to go something along the following lines: “Sure, the polar bears might get screwed over, but otherwise things will be just great. Crop yields will increase and northerners will get to have their own sun-drenched beaches”. You wish. New research* indicates that beyond temperature rises of 7C, ”zones of uninhabitability” will begin to overspread much of the world (“An adaptability limit to climate change due to heat stress” by Sherwood & Huber 2010). Not a Mediterranean world, more like Mad Max in Waterworld.

Of late climate models have been leaning to the upper range of the IPCC’s projections for global warming, e.g. the median forecast from a recent MIT study gives a rise of 5C by 2100 (with a 10% chance it will exceed 7C). According to the Sherwood paper, ”peak heat stress” (quantified by the wet-bulb temperature) never climbs above 31C across today’s climes, which is safely below the body’s normal temperature of 37C. But with a global temperature rise of 7C possible by as early as the late 21st century – even without accounting for predictable tripwires such as accelerated release of Siberian and Arctic methane – some regions of the world will be subjected to peak wet-bulb temperatures of 35C, inducing “hyperthermia in humans and other mammals, as dissipation of metabolic heat becomes impossible“. With a global temperature rise of 11-12C, a belt of uninhabitability will come to encompass the bulk of today’s densely populated areas.

Let that sink in. Forget the rainforest collapses, the icecap disintegrations, the plummeting crop yields as the increased CO2 fertilization effect is cancelled out by heat stress… during the long summers, the bulk of continental interiors below the Arctic Circle will become PHYSICALLY UNINHABITABLE for humans. Cities from Atlanta to Madrid to New Delhi will become ghost towns in the desert, crumbling relics to the long-dead gods of the industrial age.

“Periods of net heat storage can be endured, though only for a few hours… and with ample time needed for recovery”, but since “adjacent night time minima of [wet-bulb temperatures] are typically within 2-3C of the daytime peak, and adjacent daily maxima are typically within 1C”, conditions would prove intolerable “if the peak wet-bulb temperature exceeded, by more than 1-2C, the highest value that could be sustained for at least a full day”. Thus, even healthy individuals cannot sustain heat stress levels of above 35C for prolonged periods, because the skin must be at least 2-3C cooler than the body temperature, whose normal level is 37C. If the wet-bulb temperature rises to 38C, for instance, then the result will be a rise in body temperature to above 40C and death from hyperthermia.

For a preview of things to come, look no further than the 20,000 Parisians who died in the 2003 European heatwave**. True, most most were elderly folks with no air conditioning or climate control. But these things require a lot of energy. With dammed reservoirs drying up throughout Europe and hydrocarbon supplies peaking by 2030-50, a reliable electricity supply should not be expected (least of all during heatwaves). As the authors put it, “the power requirements of air conditioning would soar; it would surely remain unaffordable for billions in the third world and for protection of most livestock; it would not help the biosphere or protect outside workers; it would regularly imprison people in their homes; and power failures would become life threatening”. Not only people will begin to die away. So will plants and animals – indeed, the main catalyst for migration may become failed harvests and famine. Entire nations will have to pack up their bags and move north towards the peoples-teeming Mediterranean shores of the Arctic Ocean.

Finally, the authors point out that even these dark conclusions may be too optimistic, since “our limit applies to a person out of the sun, in gale-force winds, doused with water, wearing no clothing, and not working” (i.e. quite a lot of leeway for enhancing chances of survival!). In other words, it is quite possible that only polar, sub-polar, and mountainous areas will remain comfortably habitable (at least by the new standards).

There is much more in this fascinating article.

[vtsnowedin]

Our troops have endured temperatures in Kuwait and Iraq of up to 50C while conducting military operations, often without any air conditioning at the front and marginal amounts available in rear areas set to 32C to minimize the shock of going from air conditioning out into frying pan.
The local Bedouin population lives generation upon generation in these conditions without ever seeing an AC unit.
Clearly the authors numbers are a gross overstatement of the danger as large parts of the planet already endure the conditions he fears without a large population free area corresponding to it.

[Kieran]

Ah, but that's a dry heat vtsnowdin.

http://en.wikipedia.org/wiki/Wet-bulb_temperature

[fifthcolumn]

I was at an oilfield in Texas last july when it was 44C.

Clearly it killed me.

[RenewableCandy]

It certainly will have done if that were a wet-bulb temperature, and it went on all day and all night and you were doing somethig elaborate, like working .

[kenneal - lagger]

It will be the return of the dinosaur era as reptiles and insects grow larger in the heat and from eating all the dead humans! Crocodiles 40ft long and the Great Crested Newt a foot long!

[RenewableCandy]

Perhaps we should get rid of great crested newts then, before they eat us