The heaviest sea icing around Denmark, and no question whether the naval war since autumn 1939 contributed.

 With the extent and severity of ice during the three war winters of 1939-42 it should be possible to provide ample proof that this extraordinary situation could only have been generated by intensive military use of these waters over the time period in question. Main aspects are summarized as follows:  

• First and foremost there is the suddenness and severity of each of these ice winters for which no other cause could be attributed than the war at sea.
• It is possible to establish a direct link between the extent of activities in the Baltic Sea and the degree of icing and arctic winter conditions:
• 1939/40 intensive military activities, Gdansk, mining western Baltic and Gulf of Finland, Finnish-Russian war at sea, resulted in very heavy ice.
• 1940/41 there were only general naval activities and as such icing was less serious compared to the previous year, but nevertheless it was a severe ice winter.
• 1941/42 The Germans invaded Russia and had been fighting with the Russian Baltic Fleet for five months during June-December 1941 in the Central and the Northern Baltic Sea, resulting in the most extended and heavy icing ever observed. 

Source for the layout of sea ice  graphics: Det Dansk Meteorologiske Institute (1940, 1941, 1942)

Chapter: 3_31

Book Page: 208a

File: 980_z_SeaIce_DetDan

Image: 2010/www.seaclimate.com