(Image Source: Arctic Ice Blog)
Neven, over at the Arctic Ice Blog, has tentatively called a beginning to the Arctic sea ice melt season. Neven notes that sea ice area according to Cryosphere Today reached maximum on February 27th and sea ice extent, according to IJIS reached maximum on March 15th.
It may be a bit early to say with complete assurance that the melt season has begun. But indicators do appear to be in line with Neven’s estimate.
All measures for extent and area are now showing the sea ice to be in slow decline. Further, powerful blocking patterns over Greenland and Eastern Siberia continue pumping warm air into the Arctic even as they assault the central and northern US with continued wintery weather. As we can see in the image below, temperatures are well above normal in the Arctic for this time of year.
(Image source: NOAA)
Hotter than usual temperatures have settled over all of the Arctic with a particularly warm area hovering over Baffin Bay. These high temperatures combine with a powerful Arctic high pressure system and strong negative Arctic Oscillation to aid in sea ice erosion at the edges while stressing the central ice even as the sun begins to lift above the Arctic Circle.
Greenland is again gathering more heat energy than is usual for this time of year, with the current blocking pattern established directly over its western half. NSIDC has already noted a number of melt days for the south-east coast of Greenland and was forced to recalibrate their melt model early due to the winter emergence of heat baked into the ice sheet from last summer. This event resulted in both residual melt and higher ice-sheet temperatures.
Last of all, a large cracking event which began in February continues to expand over the Arctic. The most recent image from the Canadian Weather Office provides a very vivid picture of what’s happening:
The high pressure system currently dominating the Arctic provides very clear skies over much of the region. So we can see directly down to the ice pack. There, the Beaufort Sea displays extraordinarily extensive cracking. To the north and east, a thin line of cloud pushed up by warmer air to the south obscures a small section of the ice. But beyond that we see a region around the North Pole also displaying large and expanding cracks.
All of this — the cracking, the abnormal heat, the early Greenland melt and left over heat from last summer, would seem to mark a rather ominous start to the 2013 melt season.