Above chart, based on historic NASA land-surface air temperature anomaly data (see interactive map at the bottom of this page), shows that the average temperature anomaly rise in the Arctic (latitude 64 and higher) looks set to reach 10°C within decades.
These anomalies are based on annual averages that are also averaged over a huge area. The NASA image on the left shows temperature anomalies of over 10°C for the month December 2011.
More detailed analysis shows that, over December 2011, the highest average temperature anomaly (12.8933°C) was recorded in the Kara Sea (latitudes 79 - 81 and longitudes 73 - 89).
NOAA daily data show even more prominent anomalies, especially for the area from the Kara Sea over Franz Josef Land to Svalbard (see Wikipedia image left). NOAA temperature anomalies for January 31, 2012, seem typical for the over 20°C anomalies that this area has experienced over the period December 7, 2011, to February 11, 2012.
An animated image with the full data over the period December 7, 2011, to February 11, 2012, is displayed in an earlier post at this blog, temperature anomalies over 20 degrees Celsius. (Note: this is a 4.7MB file that may take some time to fully load.)
How is it possible for this specific area to show such huge temperature anomalies?
1. Rivers?
Could it be that warm water from rivers flows into the Kara Sea and is transferred to the atmosphere in this area? This seems unlikely, given that it is winter, while the mainland does not appear to be suffering similar temperature anomalies. The NOAA map below with anomalies for water temperatures (at surface level) also shows no particular anomalies for the Kara Sea.
2. Warm water from the Atlantic Ocean?
Above image shows that the water surface temperature anomalies are most prominent just north of Scandinavia. The reason for this is that thermohaline circulation is pushing warm water from the Atlantic Ocean into the Arctic Ocean, as evident when looking at actual water temperatures (image below).
As above image shows, warm water from the Atlantic Ocean hasn't (yet) penetrated the Kara Sea, which makes sense in winter. Therefore, this also seems an unlikely candidate to explain the over 20°C air surface temperature anomalies in the area stretching from the Kara Sea over Franz Josef Land to Svalbard.
3. Methane?
A third possibility is that methane is venting from hydrates in the Arctic and is spread by the wind around the Arctic. This would explain the record methane level of 1870+ reached in the Arctic for January 2012, as shown on the image below.
See animation of methane levels July 2011 - January 2012
