After rapid melting and temperatures 1-4 degrees Celsius above average in August, the sea ice in the Arctic Ocean has now reached the early September ice extent line of the 2007 melting record. But even if it crosses that line in days to come – setting a new all-time record in one or two weeks’ time remains uncertain.

We do know 2011 will at least end runner-up. According to the NSIDC on Monday the melting records of September 2010 and September 2008 [previously third and second] were already broken.

Low pressure moving in

There is some reason though to assume the melting will slow down somewhat in days to come. According to the NOAA Arctic Oscillation forecast shown below the Arctic region will not be dominated by high pressure systems, as the index has moved to a positive phase. This usually helps to isolate the Arctic.

More detailed weather maps do show high pressure systems as well – notably over the eastern margins of the Arctic Ocean, where temperatures will therefore be highest. This will however do little to increase further ice loss, as the Northeast Passage is open and much of the eastern Arctic is already fluid water – not ice.

Wind may shift the balance still

The western Arctic presently contains more ice, and this is where both air pressure and temperatures will be lower. Local depressions can however cause wind to become an ice-loss factor there.

But if really you’d have to place your bets, chances of this year breaking the 2007 melting record seem (just) under 50 percent.

© Rolf Schuttenhelm | www.bitsofscience.org