Recent Arctic warming and ice loss have often been linked to increases in atmospheric CO2 content, but there is little or no evidence to support that. Warming in the western Arctic is closely tied to the PDO shift in 1977. The period 1949 to 1975 was substantially colder than the period from 1977 to 2009 but little warming has occurred in Alaska since 1977. The stepwise shift appearing in the temperature data in 1976 corresponds to a phase shift of the Pacific Decadal Oscillation from a negative phase to a positive phase. The eastern Arctic went through a similar period of warming and ice loss from 1920 to 1940, followed by a cooling period from 1940 to 1980. Most of the loss of sea ice volume occurred between 1988 and 1996, during a period which was dominated by strong El Nino cycles. Volume continued to decline until 2008, but has been increasing over the last 3 years. It is an unfortunate coincidence that Arctic satellite data came on line right at the Arctic peak in the late 1970s. This has confused many people into believing that the subsequent decline in ice cover is a linear trend. Arctic cycles seem to have a period of at least 60 years, and it is much too early to reach any conclusions about the future state of Arctic ice. sciencedirect/science/article/pii/B9780123859563100087
Posted on: Sat, 30 Aug 2014 06:14:11 +0000
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