Current Trends in Antarctic Sea Ice: The 1990s Impact on a Short Climatology

Abstract

Antarctic sea ice extent, open water area, and ice area are shown to have increased 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 and 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 unprecedented El Niño?Southern Oscillation event observed from 1990 to 1995, and/or an increase in the meridional temperature gradient. Positive and negative regional trends in seasonal sea ice concentration are shown for the same period. In the western Weddell Sea negative trends in the Scanning Multichannel 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 ice season show that for many regions, changes in the mean sea ice concentration is the result of a longer (shorter) sea ice season rather than more (less) daily ice production. Results suggest that great care must be taken when interpreting short-term change in local sea ice conditions as indicative of long-term climatic forcings, and further demonstrate the need for a longer time series of sea ice data to make climatological conclusions.