Thursday, September 14, 2006



Shrinking icecaps

One of the sure signs of global warming is the shrinking of the polar icecaps. And according to a study published in the journal Geophysical Research Letters, it seems to be happening. The full article (here) reports that the amount of perennial ice - the permanant cap - in the East Arctic ocean shrank by 70% in the last year. It can be graphically seen in the images below:

There was some growth in the West Arctic, but nowhere near enough to compensate; the total icecap shrank by 14% in a single year. The normal rate of shrinkage, averaged across the last few decades, is between 0.64% and 0.78%. Some of this is almost certainly the result of unusual wind patterns pushing ice from east to west - but two thirds of the ice area was lost in the process, and the resulting area of exposed water has a much lower albedo (10% vs 40 - 50%), meaning it will warm quicker, making it more difficult for the seasonal ice to reform and possibly leading to a runaway melting of the whole icecap. This won't affect sea levels, as the ice is floating to begin with, but it will accelerate the warming trend, not to mention pretty much destroying the Arctic ecosystem. I guess we'll have to wait and see whether this is repeated over the next few years, but if it is, we can pretty much kiss the polar bears goodbye...

5 comments:

Nice images but straight line exprapolation is a but foolish.

Can you imagine an aerial photograph of the NZ southern alps in winter and contrast that with a shot of the same area in summer??
Ok, so where has all the ice/snow gone??
Panic!! Help..Help.. we must legislate something to slow this down or peoplekind will be lost..

This is a simplistic reaction of a naive, wellmeaning emotional person who cares about the enviroment.

Truth takes no notice of good intentions or genuine feelings, and is only slightly obscured by lobby groups.

Note that extrapolation into the future IS NEVER straight line..
db

Posted by David Baigent : 9/15/2006 08:43:00 AM

DB: the images compare apples with apples: they are measuring perennial ice (the ice that sticks around from year to year) rather than seasonal ice (which doesn't), and were taken on the same date (the winter solstice) each year. But if that's not sufficient, check out the continuous data in Figure 3 in the article, which shows a steady decline in East Arctic perennial ice throughout the year.

Posted by Idiot/Savant : 9/15/2006 08:56:00 AM

I have never been more scared by an image of ice...

Posted by George Darroch : 9/15/2006 11:43:00 AM

On a slightly lighter note http://ucsaction.org/campaign/vote_now_for_science_idol/?qp_source=wacucs%5fhomearspotlig The Union of Concerned Scientists has a cartoon competition (hat tip http://www.realclimate.org )

Posted by George Darroch : 9/15/2006 11:53:00 AM

Kinda makes all the present trivial political fuss here really irrelevant...

Posted by Anonymous : 9/16/2006 10:06:00 AM