Abstract
Sea ice is an important component of the global climate system and a key indicator of climate change. A decreasing trend in Arctic sea-ice concentration is evident in recent years, whereas Antarctic sea-ice concentration exhibits a generally increasing trend. Various studies have investigated the underlying causes of the observed trends for each region, but possible linkages between the regional trends have not been studied. Here, we hypothesize that the opposite trends in Arctic and Antarctic sea-ice concentration may be linked, at least partially, through interdecadal variability of the Pacific Decadal Oscillation (PDO) and the Atlantic Multidecadal Oscillation (AMO). Although evaluation of this hypothesis is constrained by the limitations of the sea-ice cover record, preliminary statistical analyses of one short-term and two long-term time series of observed and reanalysis sea-ice concentrations data suggest the possibility of the hypothesized linkages. For all three data sets, the leading mode of variability of global sea-ice concentration is positively correlated with the AMO and negatively correlated with the PDO. Two wave trains related to the PDO and the AMO appear to produce anomalous surface-air temperature and low-level wind fields in the two polar regions that contribute to the opposite changes in sea-ice concentration.
Highlights
Sea ice, an important component of the polar climate system, is a prominent indicator of global climate change[1,2,3,4,5]
It has been suggested that stratospheric ozone depletion that strengthened cyclonic circulation over Antarctica contributed to the Antarctic sea ice expansion[22], several studies have linked the increasing Antarctic sea ice cover to internally generated variability forced from the tropical Pacific that deepened the Amundsen Sea Low[23,24,25,26,27,28,29]
The associations found in previous studies, whether for the Arctic or Antarctic, between trends in sea-ice cover and low-frequency global climate oscillations such as the Atlantic Multidecadal Oscillation (AMO), Pacific Decadal Oscillation (PDO) and Interdecadal Pacific Oscillation (IPO) suggest a possible connection between the opposing trends in sea-ice cover in the two polar regions
Summary
We hypothesized that sea ice loss in the Arctic and net sea ice gain in the Antarctic during recent decades are connected via global climate oscillations, namely the AMO and PDO, and provided an initial assessment of the proposed hypothesis This assessment is constrained by the limitations of the observational record of sea-ice concentrations, the congruent findings from statistical analysis of three time series of sea-ice concentration of varying length and resolution (i.e., NSIDC, HadISST, and Twentieth Century Reanalysis) point to a possible teleconnection between the opposite changing trends in sea-ice coverage in the two polar regions. Our analyses are based solely on statistical considerations, and further analysis, including numerical modeling, is necessary to fully understand this potential teleconnection and other underlying physical mechanisms for the opposing trends in the Arctic and Antarctic sea-ice concentrations
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