Meteorologists say the cold weather is caused by a negative phase of the Arctic Oscillation, which means that cold Arctic air is flowing into southern latitudes that are normally much warmer.
This is the explanation for the recent European freezing weather and snow as mentioned in CNN. Sounds awfully like what scientists said would happen through global warming, or as Thomas Friedman called it, global weirding. Freaky. This is record-breaking weather over there, and hopefully is not a harbinger of things to come.