19 Feb '12, 12am
Global Warming News (Abnormally Warm January; Abnormally Cold Europe; Problem with NASA’s Blue Marble)
The weather pattern responsible for bringing the frigid air to Europe and Eurasia, and locking it in place, is being driven in part by a naturally-occurring pattern of climate variability known as the Arctic Oscillation . The Arctic Oscillation, or AO, is is a climate index that describes the characteristics of the atmospheric circulation over the Arctic, and a related index describes the circulation over the North Atlantic. Depending on whether it’s in a “positive” or “negative” phase, the Arctic Oscillation can bring warmer or cooler than average wintertime conditions to the U.S. and Europe. Right now the Arctic Oscillation is in a negative phase, which tends to favor colder than average weather in Europe and the U.S.