Recent intensification of extreme precipitation over Antarctica driven by increases in greenhouse gases

Abstract. Extreme precipitation is a major contributor to the total precipitation over Antarctica, as well as its variability. However, it's still poorly understood whether any recent trends in extreme precipitation over Antarctica have occurred, and if so, whether they are anthropogenically driven. Here we address this knowledge gap by using ERA5 data from 1979 to 2023 to identify six Antarctic drainage basins with significant positive trends in total and extreme precipitation. These basins include one in the Antarctic Peninsula, one in West Antarctica, and four in East Antarctica. We show that these trends are partly due to an increased occurrence of atmospheric rivers. We subsequently perform a detection and attribution analysis of these trends using precipitation outputs from global climate model CESM2 ensembles that consider all external forcing (ALL), greenhouse gases only (GHG), and anthropogenic aerosols only (AAER). Five of the basins (one in West Antarctica and four in East Antarctica) have good agreement between the trends from the ALL ensemble and ERA5, as well as between the ALL and GHG ensembles, indicating that greenhouse gases are the primary driver of the present-day trends in total and extreme precipitation over these basins. The good agreement between the ALL ensemble and ERA5 trends is confirmed using a regression-based detection and attribution technique. However, regressing the ALL, GHG, and AAER ensembles against ERA5 did not yield robust attribution to any specific single-forcing for either total or extreme precipitation, which is likely due to limitations such as the relatively small ensemble size of the simulations.