All of this got Huber
and Steven Sherwood, his colleague at Australia's University of New
South Wales, to thinking: Economic considerations aside, they asked, how
much warming can we physiologically tolerate? At what point does it get
so bad that our bodies can no longer keep cool, so bad that we can no
longer work or play sports or even survive for long out of doors? Will
we flee for colder climes? Live underground like hobbits, surviving on
cold fungus? Okay, I'm projecting -- they didn't actually ponder that last
bit that I'm aware of.
In any case, the pair crunched the numbers and published the results in a May 2010 paper in the Proceedings of the National Academy of Sciences.
Using a measurement called "wet-bulb temperature," which Huber explains
below, they modeled what might happen in several warming scenarios. At
the point where the average global temperature rise hits 10°C, "even
Siberia reaches values exceeding anything in the present-day tropics"
and many populated parts of the globe might become, if habitable at all,
places where the relatively affluent would likely find themselves
"imprisoned" in air-conditioned spaces and where "power failures would
become life-threatening." Lacking access to AC, the world's poor would
have little choice but to flee. Even "modest" global warming, Huber and
Sherwood conclude, could "expose large fractions of the population to
unprecedented heat stress."
Their paper makes for a good wish-it-were-sci-fi read for the
scientifically inclined. For everyone else, the recent heat wave
provided the perfect excuse to grill Huber (via email) on his underlying
assumptions, the hate mail he gets, and whether humans can evolve or
air-condition our way out of this prawndiddity -- that's a word my kids
came up with to describe this sort of situation, and I'm rolling with
it, since our fiasco is theirs to inherit.
First of all, is there anything you'd like to say about the recent heat wave?
It just goes to show you how random
weather can be. It tells us about as much by itself as the occasional
unseasonable cold snap. It is useful, however as an analogy for what the
future climate might look like. When climate modelers say that spring
might start a month earlier on average this sounds abstract to most
people, but the recent weather provides a good tangible example of what
statements like this mean.
Are there currently places on Earth where average temperatures are beyond the ability of our bodies to stay cool?
In the shade, with plenty of water and
ventilation, acclimated healthy adults can survive just about everywhere
currently, assuming that they aren't exerting themselves. On the other
hand, when physical exertion, sunlight, improper hydration, poor
ventilation, lack of acclimatization, and other health conditions
(including being very young or old) are a factor, many regions can
experience severe enough heat stress that serious consequences arise.
Every time someone gets heat stroke, that's someone who pushed
themselves or were pushed by circumstance outside of their zone for
regulating their temperatures. There is a wide zone over which people
can adjust their behavior to withstand very warm conditions. Our paper
asked the question: Is there a limit to that adaptability, and, if so,
how hot does the world have to get before we reach that limit?