So, it appears, according to environmental scientists, that the ozone in the Arctic has actually disappeared to the point where there's an ozone hole similar to the one above Anarctica.
From the article: "It was continuously cold from December through April, and that has never happened before in the Arctic in the instrumental record."
Of course, the standard argument will now be that it's "climate change" and that you can have sections or the earth or particular seasons that are making things worse in others. This is now the standard argument since "global warming" as a concept does not jive with the fact that things tend to be a lot colder (in many places) than warming would suggest.
The earth and its weather is a chaotic system, with more variables than can possibly be measured at the moment. (It should be noted that models are getting better, though that means that global warming – again – may not be as large a problem as originally thought.) Until we have the data to back it up (through long term measurements, instead of relying solely on ice cores – which, incidentally, show that the earth has warmed considerably in the past!) we've got a lot to study before a verdict can be drawn.(Picture from the article.)