Thursday, March 21, 2013

Sighted: Open Water in the Arctic Ocean

Everyone who has been watching Arctic sea ice knows you wouldn’t be seeing open water in the Arctic Ocean at this time of year. I am not an expert, but even I know that exposed sea water in the Arctic in March would freeze over in barely a day. For more than a week, we have been seeing signs that open water is starting to form at points around the Arctic — from visible and infrared satellite pictures, radar, even webcams — but everyone including me, it seemed, agreed that it could not really be the case — maybe in May, but not now.

But we were wrong. There is open water in the Arctic, and not just at the edges but in the Lincoln Sea, the world’s northernmost bay. We know this because yesterday a plane went there with scientists to take a look. The report and photos (from Christy’s Greenland Blog) were sobering:

Of interest, and shock to our science team, was the fact that there was a lot of open water (called leads) out over the northern sea ice, which is usually densely [packed] and thick. These leads were unexpected and certainly due to a warming climate.

I wondered after all the heat the Arctic waters took on last summer, how a normal ice cover could possibly form this winter. Superficially it looked like it did, at least at first, but the oceanwide breakup of the ice over the last six weeks says something is wrong. It looks like steam coming off the water in the photos from yesterday, and that suggests that the ocean is simply too warm to support the kind of ice we were used to in the past. It is a paradox that ice can survive at all over an ocean that maintains a temperature well above freezing all year long. Perhaps the surface layer of cold water is thinner than before, so that patches of warmer water from below are mixing in or poking through at spots. But whatever the explanation, the melt season is underway with a vengeance.