Nature Climate Change
Mt. Herschel, Antarctica. Photo by Andrew Mandemaker.
The Antarctic climate exhibits some of the largest regional temperature trends on the planet. Most of West Antarctica and the Antarctic Peninsula experienced warming and ice-sheet thinning during the late twentieth century, and this has continued to the present day. By contrast, the South Pole — located in the remote and high-altitude continental interior — cooled until the 1980s and has since warmed substantially. These trends are affected by natural and anthropogenic climate change, but the individual contribution of each factor is not well understood.
Kyle Clem and colleagues analysed weather station data, gridded observations and climate models to examine warming trend at the South Pole, and found that it was chiefly driven by the tropics. Warm temperatures in the western tropical Pacific Ocean — associated with the negative phase of the Interdecadal Pacific Oscillation — increased the delivery of warm air to the South Pole. Stronger winds around Antarctica — caused by a shift to a positive phase of the Southern Annular Mode — further boosted this warming. The authors suggest these atmospheric changes along Antarctica’s coast are an important mechanism driving climate anomalies in its interior.
The authors argue that these warming trends were unlikely the result of natural climate change alone, emphasizing the effects of anthropogenic warming and large tropical climate variability on Antarctic climate.