We investigate seasonal trends in sea ice concentration and the relative contributions of the Antarctic Oscillation (AAO), the Pacific-South American two modes (PSA1 and PSA2), and the El Nino-Southern Oscillation (ENSO). The summer range of the trend in the Antarctic sea ice is the largest, from −83.8% to 59.6% per 29 yr over the period of 1979 through 2007, while the autumn range is the least, from −49.7% to 39.6% per 29 yr for the period of 1979 through 2007. In autumn, among the four indices the largest contribution to the trend in sea ice is the AAO; in winter the ENSO and the PSA1 are better than the other two indices; during spring and summer a change of more than 15% per 29 yr is associated with PSA1. No matter the season, the spatial pattern of the residual trend is similar to that of the total trend; moreover, the combined trends of the four indices only explains less than one-third of the total trend.