Most of North America and Europe may be frozen solid this winter, but at the top of the planet, it's been abnormally warm. So warm that the Arctic sea ice shrank to its lowest extent ever recorded in January, new analysis from the National Snow and Ice Data Center shows.
This NASA image shows sea ice extent for January 2011, compared with the average size from 1979 to 2000. Blue indicates open water; white indicates high sea ice concentrations; and turquoise indicates loosely packed sea ice. The yellow line shows the average sea ice extent for January from 1979 through 2000.
Of the scale of the ice loss, Jeff Masters writes on his Wunder Blog:
Relative to the 1979 - 2000 average, the missing ice area was about twice the size of Texas, or about 60% of the size of the Mediterranean Sea. Hudson Bay in Canada did not freeze over until mid-January, the latest freeze-up date on record, and at least a month later than average.
This isn't exactly a surprise. Back in September, multiple analyses found that the Arctic Sea had less ice than ever in recorded history. NSIDC Director Mark Serreze didn't mince words, saying that "the Arctic summer sea ice cover is in a death spiral. It’s not going to recover."
For your conservative or hawkish friends, better maybe to look at the testimony of Rear Admiral David Titley, the Oceanographer of the Navy and the Director of Navy’s Task Force Climate Change. (You can watch Titley's testimony at 2:00 here.)
The volume [of ice] as of last September has never been lower in the last several thousand years...We see the probable opening of the Arctic...We expect to see about four weeks of basically ice-free conditions in the Arctic by the mid-to-late 2030s.
When talking sea ice, you want to pay attention to volume more than area. Volume reflects how much actual ice is up there. Since older ice is thicker, it has more volume, and the change in the Arctic's ice cover from predominantly old ice to "new" ice has been dramatic over the past 30 years.
Unfortunately, loss of arctic ice is one of those "positive feedback loops" we often hear about when we talk about global warming. Bright ice reflects most of the sun's light and heat back into space. The dark ocean water that replaces it, absorbs most of the heat energy. As the ice melts and turns into open sea, the whole region gets warmer and the melting process is accelerated.
I made a dinner table bet with some cousins a couple Christmases ago that the Arctic Sea would be ice-free* by 2025, and I'm thinking my chances are pretty good (unfortunately).
Eban Goodstein of the Bard Center for Environmental Policy did some economic analysis of the loss of Arctic ice, which he calls "the air conditioner for the planet." He found that
Costs caused by the additional warming, this year alone, are in the range of $61-$371 billion. By 2050, at the low end, we calculate the damages from the melting Arctic will be $2.5 trillion. The analysis projects likely damages in the tens of trillions by the end of the century.
Meanwhile, House reps are desperately trying to vote away scientific findings that greenhouse gas emissions "endanger" public well-being.
*By the way, I used Joe Romm's definition of "essentially ice-free" from a similar bet he made. For me to lose, it would have to be the case that
At no time...will the minimum total Arctic Sea ice extent be less than 10% of the 1979-2000 average minimum annual Arctic Sea ice extent, as measured by NSIDC data; provided, however, that if two or more volcanic eruptions with the energy level equal to or greater than the 1991 Mount Pinatubo shall occur between now and the end of 2020, then all bets are voided.
Ice mass grows and shrinks dramatically in the Arctic over the course of a normal year. September is generally when it's at its lowest, and I fully expect that by some September between now and 2025 we'll see an essentially ice-free Arctic Sea. The 10 percent only protects my side of the bet from straggling chunks of ice. I didn't insist on the Pinatubo void clause, because I'm a gambling man. Or just a fool.