Well, before we get into the details, look very quickly at two key words in the title — ‘Europe’ and ‘Global” (hint, hint).
As I just reported earlier today, November was the hottest November on record. However, as I know (I live here), it’s been pretty cold in Europe lately. To a lot of people, I’m sure that is more ‘proof’ that global warming isn’t happening…. Except that it isn’t proof of this at all. (And, of course, we haven’t seen any anti-global warming proof yet, in general, to counter the mountains and mountains of global warming proof documented around the world.)
Also, if you look at global temperature anomaly data, you’ll see that there are some areas of the world that are colder than average, but a lot more that are warmer than average. The point is that global warming (at this point, at least) means that the globe as a whole is warming, but not necessarily every location on Earth every month.
Anyway, why is it so cold in Europe?
NASA discusses this issue in more depth than I have the expertise to do, and it provides a good long-term graph to go with this discussion as well:
Back to the cold air in Europe: is it possible that reduced Arctic sea ice is affecting weather patterns? Because Hudson Bay (and Baffin Bay, west of Greenland) are at significantly lower latitudes than most of the Arctic Ocean, global warming may cause them to remain ice free into early winter after the Arctic Ocean has become frozen insulating the atmosphere from the ocean. The fixed location of the Hudson-Baffin heat source could plausibly affect weather patterns, in a deterministic way — Europe being half a Rossby wavelength downstream, thus producing a cold European anomaly in the trans-Atlantic seesaw. Several ideas about possible effects of the loss of Arctic sea ice on weather patterns are discussed in papers referenced by Overland, Wang and Walsh.
However, we note in our Reviews of Geophysics paper that the few years just prior to 2009-2010, with low Arctic sea ice, did not produce cold winters in Europe. The cold winter of 2009-2010 was associated with the most extreme Arctic Oscillation in the period of record. Figure 3, from our paper, shows that 7 of the last 10 European winters were warmer than the 1951-1980 average winter, and 10 of the past 10 summers were warmer than climatology. The average warming of European winters is at least as large as the average warming of summers, but it is less noticeable because of the much greater variability in winter.
Finally, we point out in Figure 3 the anomalous summer warmth in 2003 and 2010, summers that were associated with extreme events centered in France and Moscow. If the warming trend that is obvious in that figure continues, as is expected if greenhouse gases continue to increase, such extremes will become common within a few decades.
Image and Caption Credits: NASA