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Thursday, September 20, 2012

Last refuge for multi-year Arctic sea ice breaking up -- Axel Heiberg Island is now free of ice shelves

UPDATE2:  I've found a MODIS photo from 2008 that shows this same situation.  And the ice shelves along the west coast of Ellesmere Island were quite small.

So in my mind, why is it common currency at all that this region will have any multi-year sea ice hanging around?  It is all moving toward either the Nares or Fram Strait.  

There is no haven for multi-year ice.

UPDATE:  A commenter at neven's reminded me that the Canadian Met Office has regional photos of the Canadian Arctic:

See the white dot?  It sits on Ellesmere Island.  To the south is Axel Heiberg Island.  Note the strait between them.  Ice at the mouth of the strait is all broken up.  To the north, along the west coast of Ellesmere, the land-fast ice shelves are disappearing. Directly to the north of the northern tip of Ellesmere was where the "ice arches" used to be at the head of the Nares Strait.  It's all broken up there too.

Dear Readers,

This time the post is actually written by me for a change --

Axel Heiberg Island is in the Canadian archipelago and lies directly to the west of Ellesmere.  Yesterday, to my great astonishment, on MODIS images one could clearly see that all of the ice shelves and ice in the straits along this island had broken up.  This particular region was supposed to be part of the last stand of multi-year ice for the next decades.  

Further, the sea ice north of Greenland at the head of the Nares Strait is completely broken up and travelling south through the Nares, i.e., the "ice arches" are gone.  So, that area is also not going to be a refuge for multi-year sea ice.  This leaves only the land-fast ice shelves along the west coast of Ellesmere as a representation of multi-year ice.

In recent years, the ice in the fjords all along the coast of Greenland (on both the west and the east) has not refrozen during the winter months to its previous thickness.  This could be seen in the radar images from the Envisat satellite, which unfortunately went offline forever in April.

The floating ice tongues of glaciers like the Petermann (which is in the far north) are thinning from the bottom.

This says to me that there is a gross underestimation of the amount of heat entering the Arctic via the north Atlantic.

Furthermore, there is a lack of good understanding of the currents that bring this warm water into the Arctic Sea and the Canadian archipelago, and of how these currents may be changing.

At the current rate of underside melting, it seems unlikely that multi-year sea ice will be preserved along the west coast of Ellesmere Island for very long.  This may just depend on the vagaries of weather in particular years, but in recent years there has been much persistence of a high-pressure zone in this general area of the Arctic that has meant more surface melting, particularly on Greenland.

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