Detection of temperature and sea-ice-extent changes in the Antarctic and Southern Ocean, 1949-96

Abstract

Surface temperature data for the occupied Antarctic stations (for the period 1959-96) and Southern Ocean island stations (1949-96), and sea-ice-extent data (1973-96) are analyzed to provide trends over the indicated time intervals. The mean trend (mean slope of linear regressions through the annual mean station data) for the Antarctic stations indicates a warming of 1.2°C (100 a)−1. The slope of the linear regression fit to a composite of the mean station anomaly data indicates a warming rate of 0.9°C (100 a)−1. For the Southern Ocean island station data, warming rates of 1.0° and 0.7°C (100 a) −1 are indicated by the two methods. For the sea-ice data, no significant trend is detectable over the satellite era, 1973-96, but for the longer period commencing in the mid-1940s there is some evidence of a decrease in sea-ice extent from whaling records recently published.