NSIDC Arctic sea ice news July 2011

NSIDC has just released its July analysis.

Some interesting tidbits:

Arctic sea ice extent averaged for July 2011 reached the lowest level for the month in the 1979 to 2011 satellite record, even though the pace of ice loss slowed substantially during the last two weeks of July. Shipping routes in the Arctic have less ice than usual for this time of year, and new data indicate that more of the Arctic's store of its oldest ice disappeared.

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Ice loss slowed towards the end of July as a high-pressure cell centered over the northern Beaufort Sea broke down and a series of low-pressure systems moved over the central Arctic Ocean. This change brought cooler conditions and likely pushed the ice apart into a thinner but more extensive ice cover.

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Until recently, the central Arctic Ocean and Canadian Archipelago served as refuges for some of the oldest, thickest ice. However, the new data show that ice age is now declining in these areas. A map of ice age for the third week of July, combined with sea ice concentration for July 31, 2011 (Figure 4) shows that in the eastern Beaufort Sea, the ice has essentially melted back to the edge of the multi-year ice cover (ice older than one year). Multi-year ice is more resistant to melting completely in summer, so it is not yet clear how much more ice will melt. Another tongue of old ice extends from near the pole towards the New Siberian Islands.

Figure 4. These maps show sea ice concentration (left) and ice age (right) over the Arctic Ocean. In the Beaufort Sea off the coast of Alaska, ice has melted back to the edge of a tongue of older, thicker ice. In the ice age image, red shows ice 5 years old and older, green shows 4-year-old ice, light blue shows 3-year old ice, dark blue is second-year ice, and purple shows first-year ice. —Credit: NSIDC, data courtesy M. Tschudi

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On the other side of the Arctic, the Northwest Passage is still choked with ice. However, data provided by Stephen Howell of Environment Canada show that ice loss in the Northwest Passage is well ahead of average (Figure 5), nearly matching last year when, according to Canadian Ice Service (CIS) analyses, sea ice in the Parry Channel (the northern part of the Northwest Passage) reached the lowest levels in the CIS records dating back to 1968. Whether a navigable channel does indeed open this year will depend on weather conditions through the next few weeks, but so far, it looks possible.

Read the whole report HERE.

Comments

[Simon]

I'm finding it remarkably difficult to see the "arms" of older ice reflected in the concentration map. Is the relationship between ice age and resistance to melt breaking down?

[maltose]

Neven, PIOMAS has updated! July 31st volume is 6,494 km^3, which is only 46 km^3 above the 2007 volume minimum of 6,548 (which we have probably already passed on August 1st).

[maltose]

Sorry, I meant that the 2007 minimum was 6,458 km^3.

[Neven]

Thanks for letting me know, maltose. I'll put up a post later today.

[Wipneus]

I have upgraded my PIOMAS graphs.

Daily Arctic Ice Volume:

http://img5.imageshack.us/img5/4533/piomastrnd4.png

Monthly Ice Volumes with exponential trends:

http://img850.imageshack.us/img850/2294/piomastrnd2.png

To the latter I have included the June and July trends based as they where on data up to 2010 (dotted lines). Both months show an more rapid decline with the new 2011 datapoint.

[Neven]

Thanks, Wipneus. Post is up.

[michael sweet]

Simon,
The Beaufort sea has melted very slowly for the past several weeks. Once the melt reached the edge of the old ice it slowed a lot. That ice now seems to be starting to melt out completely. We will have to wait to see if August has enough sun to melt out that tongue of old ice completely.