The NSIDC has released it’s latest update; Arctic sea ice extent is still declining, though more slowly now. The figure they are giving today is 4.24 million km2. Looking at that curve and taking into account the date, a final figure of between 4.1 and 4.2 seems likely.
There is an interesting discussion on the page about the whys and wherefore, citing work from Polyakov and Shimada which respectively deal with the Barents and Bering Sea processes. Most obvious is the connection between temperature anomalies and sea level. As they point out, with no ice to prevent heat loss from the ocean, the ice level and temperature feed off each other.
The NSIDC also reminds us that the albedo feedback effect, which is pretty clearly what is happening in the East Siberian and Chuchki Seas, and could be having an effect on keeping the North West Passage open, has long been expected from the output of global climate models. On the face of it, the cureent situation in the Arctic looks like straight evidence that climate models can (and have) correctly model (or project!) large-scale climate processes.
From the blog data, it is clear that some of you are interested in the state of the Northern Sea Route, which I have been incorrectly referring to as the North East Passage (apparently, this terminology is antediluvian). Thanks to Hank Roberts ans Steve Bloom, among others, we can now keep a close eye on the satellite images from the MODIS rapid response near-time image bank. The TERRA image for 12.35 today should show the Taymyr Peninsula, the ‘bulge’ in the mainland, next to which a number of small boats are trying to make a passage (see other posts for links).
There are still strong Sea Surface Temperature Anomalies (from the AARI) in the Laptev Sea, and, though the ice drift forecast is now a few days old, it still shows a Northward drift in the area. This is too coarse to show local eddies or back currents, so it’s hard to be sure, but conditions should remain adequate for a few more days for the passage to clear to a level of less than 30% concentration, of ice less than 1ft thick. It would seem unlikely that the entire passage will clear in the way the NWP has, but if it is navigable, without icebreaker assistance, by a non-commercial or small commercial vessel, this should count as being ‘clear’ for the sake of the argument.
As has been said elsewhere, don’t be fooled into thinking that we’re talking about an ordinary ocean trip here: temperatures are still incredibly low, there is not much daylight (though still some twilight), and conditions can go ‘bad’ very quickly. Even if a small boat could get through, there is danger from ‘bergy bits’ and ‘growlers’, large chunks of very hard ice which are hard to see until they are very close.
For some years, shipping companies, and the Russians in particular, have been looking into the viability of the Northern Sea Route. If the sorts of conditions we have seen this year persist into the coming decades, then this will become an important and economically viable route for major shipping between the Atlantic and the Pacific. This would have ramifications in all sorts of places, from Panama to the Suez to the many ports which rely on the huge international shipping business for their livelihoods. It would also suggest that new ports would need to be opened on the Siberian coast; this in turn would stimulate development along the North of Canada and Alaska, which means a northward population shift and other side-effects.
I’ll keep an eye on things and post regular updates. For a fascinating (but often technical) discussion of the Arctic sea ice, RealClimate has a thread which has been active for weeks now, with hundreds of comments.