Climate Fact: Arctic Temperature Trend Amplification and the AMO
Temperature records suggest that the Earth’s surface temperatures warmed during the early part of the 20th century, cooled from the period 1940-1970 and have since been warming. While Arctic temperature trends have corresponded to this general warming and cooling pattern, it has followed these trends more severely. During the warming period from 1910-1940, the Arctic warmed about 5.4 times the rate of the rest of the planet and from 1970-2008 it warmed at about twice the rate. During the cooling period of 1940-1970 it cooled at about nine times the rate of Earth’s average trend. What is behind this temperature trend amplifications in the Arctic? The best explanation is the behavior of the Atlantic Multidecadal Oscillation (AMO), or the periodic 65-year warming and cooling of North Atlantic sea-surface temperatures due to a strengthening and weakening of the ocean currents that bring warm waters from the tropics into the far north. If the Atlantic had a cold anomaly in the far northern regions that was balanced by a warm anomaly in the subtropics, the Arctic would noticeably cool while the rest of the planet would show little or no change in temperature. The coincidence of warm AMO periods (warm waters in the Arctic) and cool AMO periods (cool waters in the Arctic) during periods of global warming and cooling respectively helps to explain why the Arctic has shown such severe warming or cooling trends compared to globally averaged rates.
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Source: Chylek, P et al. “Arctic air temperature change amplification and the Atlantic Multidecadal Oscillation.” Geophysical Research Letters 36 (2009): L14801.
