Breaking news! December can still be cold and snowy over parts of the Northern Hemisphere. Don’t look to the American media for much information about European weather; it’s about as foreign as driving on the wrong side of the road. But, in Britain, Italy, and the rest of Europe, the past several weeks have seen “the Arctic refrigerator door” swing wide-open. Here are some example headlines:
Arctic freeze to last another month as AA warns of ‘worst driving conditions imaginable’ for Christmas getaways: Mail Online: “With temperatures expected to fall to -15c (5f), the Met Office said this is ‘almost certain’ to become the coldest December since records began in 1910.”
Europe travel mayhem as arctic freeze strikes again: AFP: “In Italy, rare snowfall disrupted the tourist destinations of Pisa and Florence, forced both airports to close and severely disrupted traffic and the region’s rail network.”
Thankfully, Dr. James Hansen has this figured out: Europe is one-half Rossby wavelength downstream from a partially frozen Hudson Bay, which causes Europe to become colder, or something: from NASA’s government funded blog:
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.
This is the trap that statistical/data manipulators like Hansen have fallen into: in the past, they would freely say: “of course you cannot attribute one weather event to global warming, but the likelihood of that event has become higher because it’s the extremes that are going to increase the most”, or something like that. Now, there is no pretense to equivocate about what the atmosphere is doing: weather has become climate, and necessarily so for the continued narrative of global warming alarmism. The trap is that they do not understand the underlying meteorology or climatology from basic dynamics — instead giving hand-wavy explanations with some citations thrown in from their colleagues.
To adequately attribute an ongoing weather/short-term climate event to AGW, considerable data analysis and time must be invested into researching many different avenues. It is a disservice to those interested in climate variability for senior scientists to supply hand-wavy, reflexive out-of-their-behinds explanations to the media to further their obvious political agenda. This actually goes for both sides of the climate aisle.
In the meantime, Europe continues to enjoy the effects of global warming or the Arctic Oscillation or the North Atlantic Oscillation, or something. It’s hubris and arrogance to think you have the Winter of 2010-2011 all summed up before it even starts.