Volume 6A (2010) Issue SpecialEdition Pages 1-4
In this study, we investigate the mechanism of the arctic warming pattern in surface air temperature (SAT) and sea ice concentrations over the last two decades in comparison with global warming since the 1970s.
According to the analysis result, it is found that the patterns of SAT and sea ice before 1989 are mostly determined by the Arctic Oscillation (AO) in winter. In contrast, arctic warming patterns after 1989 are characterized by the intensification of the Beaufort High and the reduced sea-ice concentrations in summer induced by the positive ice-albedo feedback.
It is concluded that the arctic warming before 1989 especially in winter was explained by the positive trend of the AOI. Moreover the intensified Beaufort High and the drastic decrease of the sea ice concentrations in September after 1989 were associated with the recent negative trend of the AOI. Since the decadal variation of the AO is recognized as the natural variability of the global atmosphere, it is shown that both of decadal variabilities before and after 1989 in the Arctic can be mostly explained by the natural variability of the AO not by the external response due to the human activity.