Extreme temperature trends in Antarctica exacerbated by explosive atmospheric rivers

In many regions, extreme temperatures increase faster than background global warming due to complex atmospheric circulation changes. This has been overlooked in Antarctica. Here, we examine extreme temperatures recorded at 16 weather stations since 1950, and identify their changes and drivers. Over the Antarctic Peninsula and the South Pole, 10-year return level temperatures increased by up to 1.19°C per decade since 1980, outpacing mean temperature trends. Most extreme events, including statistically implausible or black swan events, were driven by intense atmospheric rivers linked to Rossby wave trains forced by tropical Pacific convection. In contrast, 10-year return level temperature decreased over most of East Antarctica, despite increasing atmospheric river activity, as the mean cooling muted the impacts of warm intrusion until recently. Our results highlight how the entire continent could become vulnerable in a warmer climate or enhanced tropical convective activity, as illustrated by the March 2022 heatwave.