Record Sea Ice conditions for the Baltic Sea region ahead?
By Arnd Bernaerts, 31 December 2010

Are we heading towards a new sea ice record in Northern Europe? The icing progress during December 2010 has meanwhile reached a stage that may end with a new record at the end of the winter season. Exceptional coverage has happen only about 18 times during the last 300 years, Fig. 1[1], of which the last three times

occurred in the 1940s, namely 1939/40, 1941/42, and 1946/47. During the last days of 2010, new ice has been forming in the Kattegat and Skagerrak in an rapid speed (Fig. 2[2], violet), which is presumably the most extensive ever observed so early.

This  December is likely to be getting the coldest from England[3] to Sweden[4] and in the USA[5] since long. In the  Bay of Bothnia icing started as usual around the 20^th of November, but over the next weeks during December the ice cover reached a considerable higher level as the long term mean; Fig. 3 (left) indicates the extent on the 27 December versus ‘normal’ per 01 January (right). Fig.4 shows the sea ice conditions over the entire region.

 Last winter, which came several weeks later as this year, but developed to the coldest for about 30 years, the Bay of Bothnia was fully ice covered since the 8^th of January, and the highest ice cover, with  244,000km², was reached on the 17^th of February 2010[6]. That meant, it was an average ice winter (see Fig. 1). Much shorter was the ice season in the West. Significant icing started around Denmark only after New Year Day, but reached a impressive cover by the 17^th February (Fig.4), to disappear almost completely within the next 10 days. The winter ice was modest, while the last winter with major ice formation and obstructions to shipping was 1995/96.

 That surprises. Although it was the coldest in Northern Europe for 30 years, there have been at least fours years during that time period with considerable larger ice extent (see Fig. 1). By now the current ice cover is already close to the maximum extent on February 17th, 2010 (Fig. 5), ditto in the Kattegat & Skagerrak (Fig. 2 & Fig. 6) which seem to promise the development of a very interesting sea icing process.  

For comparision:
The ice cover per 21 Dec.2011