On the Interpretation of Antarctic Temperature Trends

Abstract

Abstract Determining the rate of atmospheric warming in Antarctica is hampered by the brevity of the temperature records (<50 years), which still contain signals of decadal circulation variability in the Southern Hemisphere. In this note it is demonstrated that Antarctic warming trends have been regionally modified by slow circulation changes and associated changes in sea-ice cover: decadal weakening of the semiannual oscillation since the mid-1970s has limited the meridional heat exchange between Antarctica and its surroundings, so that warming trends have leveled out since then. In contrast, northerly circulation anomalies in combination with decreased sea-ice cover have regionally enhanced low-level warming, for instance in the region of the Antarctic Peninsula. Based on this knowledge, the authors propose a background Antarctic warming trend of 1.30 ± 0.38°C (century)−1, representative of the period 1957–95.