Wednesday, September 05, 2007

Slightly-fresher lake chronicles, cont.

So polar ice has hit a new record low, showing a precipitous decline year-on-year. I cropped this picture to show Canadians that, yes, huge chunks of the Arctic are now ice-free. The Northwest Passage is described as "the most navigable that people have see since monitoring began".

That magenta line shows the average sea ice extent from 1979-2000, so August 2007 is already obviously below that. To put it another way, this isn't just a usual summer melt -- this is way out of the norm. But the truly terrifying piece is this one, showing the declines for the last 20 years or so:

This is the single largest year-on-year decline shown, if I'm reading this right. That said, you can also see that some previous declines have been followed by substantial recoveries the following year -- not enough to offset the decades-long trend, but we should be prepared, next summer, for the possibility of a larger icepack than this summer. No, it won't mean that global warming is a hoax.

(Update: Just to be clear, the averages shown in the figures above are the August averages, not the yearly averages.)