Sunday, September 23, 2012

Can we just forget about the polar bears for a while?

Not that I don’t care, but ever since An Inconvenient Truth made the polar bear the iconic image for climate change, it’s become a distraction from the real debate.

Take this piece of logical legerdemain from Matt Ridley. Admitting through gritted teeth that actually, really, oh-all-right the Arctic sea ice is retreating, he plays a misdirection game: “In the Holocene Optimum there was no collapse of the polar-bear population”.

Keep calm and carry on, people, the polar bears will get by somehow.

That, of course, ignores two itsy-bitsy ever-so-tiny details.

  • 1.     Polar bears and arctic foxes are only so-so as a proxy to answer the question “what impact would an ice-free Arctic have on species in the region?” Ridley somehow manages to overlook species, like the muskox and the steppe bison, that may have suffered a population collapse in the Holocene. It’s odd that he’d miss these examples, since he’s a zoologist.
  • 2.     The survival of the polar bear is not a benchmark for the impact of warming on human society.

Ridley ends with this red herring:

“The sea-dominated Southern Hemisphere is certainly warming more slowly than the land-dominated Northern Hemisphere, but it has still been warming. If warming is supposed to be "global," shouldn't sea ice retreat at both ends of the world?”

That’s a misleading question – since it’s been answered. Ridley seems to be placing a bet that his readers don’t know this. His readers don’t realize that the Antarctic is land, not sea; that the freshening of the Southern Ocean allows it to freeze more readily.

Most importantly, if all of the Antarctic ice is taken into account – both land and sea ice – the Antarctic ice cap, like the Arctic, is shrinking.

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