According to Cryosphere Today, Saturday’s Arctic sea ice area measured 10.22 million square kilometers. By Monday, that number had dramatically fallen to 9.81 million square kilometers. This loss of 410,000 square kilometers over the course of two days is extraordinarily rapid, even for a time of year when melt has tended to accelerate. On sea ice area graphs, it makes the last few days look like area numbers fell off the edge of a cliff. (Note that Cryosphere Today area numbers usually lag by a few days. So what we’re actually seeing is area measurements through Friday, June 7th).
Up until recently, sea ice area melt had been relatively moderate. But now, after a week of consistent 100,000+ square kilometer daily losses, and two days of 200,000+ losses, sea ice area is only a smidge above that of record melt year 2012 on the same day in June. In total, more than 800,000 square kilometers were lost over the course of the past week. This melt rate, if sustained, would render the Arctic ice-free by late August. If we look at past records, it is not likely that these rates of loss will continue. But past records may not prove a good guide in the current age of fragile Arctic ice. It is quite possible, given the ice’s fractured, frail, and mobile state, that such enormous melt rates, in the worst case, could be sustained or even exceeded. In this event, we would witness a total collapse of Arctic sea ice by the end of this year. So should current dramatic melt rates be sustained or worsen, we may be upping our forecast chances for near total melt by end 2013 (still at 10%).
In any case, warnings that we were not out of the woods after a slower than expected melt during May, seem to have born out in spades.
Persistent Arctic Cyclone + Rapid Edge Melt = Brutal Combination
The twin forces driving this sea ice loss are the Persistent Arctic Cyclone of 2013 (PAC 2013 — I’ve decided to keep this name. Neven has sanctioned it, even as he playfully recommended calling it Rocky Balboa, which would be entirely appropriate for this dogged storm.), which we began warning about on May 30th in The Big Thin Begins, and a rapid edge melt that also began in early June.
PAC 2013 has, for more than two weeks, been invoking a number of forces detrimental to sea ice in the Central Arctic. It has pulled warmer water up in a column beneath it, melting the bottom ice. It has, through cyclonic action, dispersed the ice away from its center of circulation. And, via energetic storm winds, it has churned and disturbed the surface waters just beneath the ice or at the surface, creating a mixing action that also erodes the ice.
Together, these forces have dramatically reduced the Central Arctic Sea ice. Sea ice thickness, according to the US Navy, after already thinning somewhat, looked like this on May 30th:
Today’s most recent measure shows the central ice pack suffering substantial reduction since that time:
Note the major thinning in a region of the thickest ice even as thinner regions closer to Siberia ablated further over the past ten days.
Cracks visible in the Lance-Modis satellite shots confirm an increased breaking of the sea ice even just north of the Canadian Arctic Archipelago, where the ice is thickest. Through a combination of bottom melt and sea ice dispersal, it appears that a broad region of this ‘most resilient’ ice lost between .5 and 1 meter worth of sea ice over the past ten days. By June 6th, these losses began to show up in the, less sensitive, Cryopshere Today concentration graphic. By June 8th, a large swath where sea ice concentration had dropped to between 60 and 70 percent was indicated in the region most affected by PAC 2013:
(Image source: Cryosphere Today)
Note the large swatch of red running directly through the Central Arctic. That’s a broad region of ice thinned by our Persistent Arctic Cyclone showing up in the Cryosphere Today measure.
Today, the cyclone has shifted toward the Laptev Sea and is dramatically churning the thinner ice there, shifting its special brand of havoc closer to the Siberian coastline. We’ll discuss more about this new development in an upcoming PAC 2013 forecast.
As PAC 2013 churned through the Central Arctic, melt accelerated at the ice periphery. In the Canadian Archipelago, large regions of ice turned a characteristic shade of blue as melt lakes developed and insolation began to do its work there. Both Hudson Bay and Baffin Bay also saw dramatically increased rates of melt. This larger region of the Canadian Arctic saw a powerful influx of higher temperatures. A pulse of warmth that likely pushed melt faster. Temperatures of 10-20 degrees Celsius became a common event near Hudson Bay and southern portions of the Canadian Archipelago. Above freezing temperatures stretched far northward, driving deep into the Beaufort Sea.
Across the Arctic Ocean, the Laptev Sea began to melt at a faster pace even as a region of the Chukchi Sea displayed a dramatic and rapid disintegration of sea ice. You can see this rapid melt by comparing the Lance-Modis image from June 2nd to today’s Lance-Modis shot of the region:
This is what Chukchi Sea ice looked like on the 2nd of June (Image source Lance-Modis).
And here is what it looks like today (Image source: Lance-Modis)
Note the clearing of most ice from the Bering Straight even as the ice edge retreated northward toward an increasingly fractured and thinned polar ice cap. As warmer air is expected to enter the Chukchi over coming days, it appears that conditions will continue to favor rapid edge melt there.
Weather model forecasts also show warm air flooding into many regions at the ice edge, growing especially prominent in the Beaufort, Chukchi, and East Siberian Seas. Meanwhile, PAC 2013 is expected to continue to churn through the Central Arctic. These conditions are now projected to persist until at least June 20th, at which point our Persistent Arctic Cyclone will have lasted nearly a month.
As noted above, this combination of conditions: warm air invasion at the ice edge, historically thin, fragile, and mobile sea ice, and a Persistent Arctic Cyclone (PAC 2013) are likely to continue to promote rapid to very rapid melt in the Arctic as June continues to advance. Though 200,000 kilometer per day sea ice area loss is extraordinarily rapid and dramatic, the potential exists for single day losses to exceed even this highly radical number. A sea ice cliff for June 2013, thus, appears to be a distinct potential.