30-Year satellite record reveals contrasting Arctic and Antarctic decadal sea ice variability

[1] A 30-year satellite record of sea ice extents derived mostly from satellite microwave radiometer observations reveals that the Arctic sea ice extent decreased by 0.30 ± 0.03 10 km/10 yr from 1972 through 2002, but by 0.36 ± 0.05 10km/10yr from 1979 through 2002, indicating an acceleration of 20% in the rate of decrease. In contrast, the Antarctic sea ice extent decreased dramatically over the period 1973–1977, then gradually increased. Over the full 30-year period, the Antarctic ice extent decreased by 0.15 ± 0.08 10 km/10 yr. The trend reversal is attributed to a large positive anomaly in Antarctic sea ice extent in the early 1970’s, an anomaly that apparently began in the late 1960’s, as observed in early visible and infrared satellite images.