Current trends in Antarctic sea ice: The 1990s impact on a short climatology

Antarctic sea ice extent, open water area, and ice area are shown to have i ncreased significantly during the period 1987-96. These trends are largely attributable to an increase in these parameters during the mid-1990s. It is suggested that these changes may be due to modifications in the position a nd depth of the circumpolar trough that impact the sea ice directly via the atmosphere and indirectly via the ocean, and could be a response to the un precedented El Nino-Southern Oscillation event observed from 1990 to 1995, and/or an increase in the meridional temperature gradient. Positive and neg ative regional trends in seasonal sea ice concentration are shown for the s ame period. In the western Weddell Sea negative trends in the Scanning Mult ichannel Microwave Radiometer (1978-87) and Special Sensor Microwave/Imager (1987-96) period sea ice data are consistent with the rates of temperature increases observed over the past 50 yr. Trends in the length of the sea ic e season show that for many regions, changes in the mean sea ice concentrat ion is the result of a longer (shorter) sea ice season rather than more (le ss) daily ice production. Results suggest that great care must be taken whe n interpreting short-term change in local sea ice conditions as indicative of long-term climatic forcings, and further demonstrate the need for a long er time series of sea ice data to make climatological conclusions.