Denialists: Winter is cold, So There is no Global Warming
December 20, 2010
The image above was generated by a great web page from NOAA’s Earth System Research Lab
If you look at the temperature scale, and then at the chart, you can see the large swaths of cold air that have spilled out of the arctic, and are covering parts of Europe, North America, and Eurasia. And, you can also note how much warm air has been drawn up into the Arctic, causing temperatures that are 5, 10 and even 15+ degrees C warmer than normal.(the temps are anomalies, ie how much warmer or cooler than compared to the 1968-1996 mean)
So the situation on the ground exactly follows a most interesting presentation from last week’s American Geophysical Union event in San Francisco, which came to us from Jeff Masters Wunderblog, Hot Arctic, Cold Continents which I excerpted here.
The talk was given by Dr. Jim Overland of NOAA’s Pacific Marine Environmental Laboratory, one of the world’s experts on Arctic weather and climate (I spent many long months flying in the Arctic with him during the three Arctic field programs I participated in during the late 1980s.) Dr. Overland discussed the remarkable winter of 2009 – 2010, which brought record snowstorms to Europe and the U.S. East Coast, along with the coldest temperatures in 25 years, but also brought the warmest winter on record to Canada and much of the Arctic.
He demonstrated that the Arctic is normally dominated by low pressure in winter, and a “Polar Vortex” of counter-clockwise circulating winds develops surrounding the North Pole. However, during the winter of 2009-2010, high pressure replaced low pressure over the Arctic, and the Polar Vortex weakened and even reversed at times, with a clockwise flow of air replacing the usual counter-clockwise flow of air around the pole. This unusual flow pattern allowed cold air to spill southwards and be replaced by warm air moving poleward. This pattern is kind of like leaving the refrigerator door ajar–the refrigerator warms up, but all of the cold air spills out into the house.”
The pattern, according to Overland, is repeating itself this year, and may be a sign of a new air flow pattern brought on by changes in northern sea ice. More at the link.