Why did it came to extreme the

sea ice conditions during WWII?

http://www.2030climate.com/a2005/03_21-Dateien/03_21.html

Can it be ignored that there had been very low sea ice conditions from 1984 to winter 1938/39, followed by three extreme sea ice years, which are the severest in succession since record had been taken since 1750? The circumstance are so extraordinary that it seems unacceptable to claim it was due to “natural variability”.   

Extract from Chapter 3_21, page 180: Summary concerning the third WWII winter 1941/42:

Although the Baltic Fleet and the Reichsmarine never met face to face for a traditional sea-battle, ‘Barbarossa’ unleashed destructive force in the Baltic Sea, which this region had neither experienced at any time during World War I, nor during the two principal clashes two years before, when the Reichsmarine attacked Gdansk and the Baltic Fleet shelled and bombed Finnish islands and cities along the Gulf of Finland in December 1939. While the latter events had been able to make a significant contribution to the first war winter conditions, the third war winter owes its origin even more to anthropogenic reasons.      

Chapter: 3_21

Book Page: 179

File: 933_FinishSeaIce

Image: 2010/www.seaclimate.com