The present temperature regime of the Norwegian and Greenland Seas results largely from the warm Norwegian Current. This current is partially responsible for the maritime climates of northern Europe and Scandinavia, and it controls the distribution of planktonic Foraminifera and the extent of sea-ice cover in the Norwegian and Greenland Seas.

Analyses of 6 piston cores show that Norwegian Sea temperatures during most of the past 150,000 yr have been much lower than they are now. Only between 127,000 and 110,000 B.P. did temperatures approach or surpass present-day temperatures. For the remaining time, foraminiferal faunas were similar to or even less diverse than those of today in the northern Greenland Sea, where ice cover is present in winter. This suggests that during most of the last 150,000 yr, ice covered all of the Norwegian and Greenland Seas, probably on a year-around basis. As a result, northern Europe and Scandinavia did not receive air warmed by the Norwegian Current as they do now. Additionally, the presence of total sea-ice cover prevented the formation of Norwegian Sea overflow water, thus altering the deep circulation of the Atlantic