It's not that cold. It's the Gulf Stream, which flows south-north from a tropical origin so it's warmer than the water on the US west coast, for example, which flows north-south from the Bering Sea on the Alaska Current.
The Gulf Stream is also why northwestern Europe is as temperate as it is while being at the same latitudes as southeastern Alaska and northern British Columbia which have heavily glaciated coastlines.
If the Norwegian fjotds were in Alaska, for example, they would be the mouths of giant glaciers, but they aren't, again because of the warming influence of the Gulf Stream.
Not sure if that makes sense, but anyway.