Europe has long had warm winters starting say several years ago. Back in 1944 during the Ardennes offensive there was like a foot of snow. You can see for yourself the weather of Berlin, Stockholm, Warsaw, Helsinski. Not a single snow flake in Europe.
Global warming is measured in hundredths of a degree Centigrade per year. So this winter is not a direct measurement of global warming. That being said, global warming can trigger other temperature changes that are locally much greater. Triggering more frequent or stronger El Ninos can be one example. Another possibility is that it may trigger a changed direction of the ocean current that now warms Great Britain. If that current goes somewhere else, Great Britain will be much colder. Keep in mind that even a small increase in the global temperature represents a huge amount of energy and can cause large weather changes.
El Ninos basically is : "warmer ocean water" it has had a thermal effect by keeping the arctic air from reaching as far south as it usually does, some call it Indian summer for some reason. The arctic air is finally reaching the south where I'm at, it was 18 degrees f this morning in NC. On Christmas it was 73 degrees f lol.