Sea ice plays an important role in the state and variability of regional and global climate. As a sensitive indicator of future climate change, a detailed understanding of recent sea ice variability and its association with physical processes at a variety of spatial/temporal scales is necessary.

Trends in the satellite-derived Antarctic sea ice concentrations (January 1979-December 2002) show a pronounced increase (decrease) in the central Pacific sector (Bellingshausen/western Weddell sector), which exceed 95% confidence level. Positive polarities of the Antarctic Oscillation (AAO) lead to more (less) ice in the eastern Ross/Amundsen sector (Bellingshausen/northern Weddell sector), which are qualitatively opposite to the impacts of positive polarities of the El Niņo-Southern Oscillation (ENSO).

Trends in the satellite-derived Arctic sea ice concentrations (October 1978-September 2002) show pronounced decreases in the Barents/Kara Seas, between the Chukchi and Beaufort Seas, the central Sea of Okhotsk and a portion of the Hudson/Baffin Bay, exceeding the 95% confidence level, and increases in the Bering Sea and a portion of the Canadian Archipelago. Qualitatively speaking, positive phases of the Arctic Oscillation (AO) and ENSO produce similar ice changes in the western Arctic, but opposite ice changes in the eastern Arctic.

The mechanisms leading to the covariability 1) between the Antarctic sea ice and the a) AAO and b) ENSO, and 2) between the Arctic sea ice and the a) AO and b) ENSO are demonstrated. For the last 24 years, the magnitude of the ice changes associated with the positive AAO (AO) trend and the negative ENSO trend is much smaller than the observed regional Antarctic (Arctic) ice trends. Therefore, to understand recent sea ice variability and how sea ice may change as climate warms, we need to investigate less understood large-scale processes and the potentially complex nonlinear interactions among large-scale processes, as well as more local-scale processes.