Hydroclimate changes in Antarctica during 1900-2014

Abstract The hydroclimate of southern high latitudes impacts the Antarctic Ice Sheet (AIS) and, by consequence, the global climate. In the AIS, precipitation (PPT) is directly related to the surface mass balance, and it has increased over the past centuries as a response to global warming. In particular, this upward PPT trend accelerated in the late 20th Century, when anthropic activity became as relevant as natural agents in forcing the climate. Using data from 23 Coupled Model Intercomparison Project Phase 6 (CMIP6) models and seven reanalyses, we described PPT changes Antarctica considering the periods before (1900–1979) and after (1980–2014) the year 1980. In the region south of 60o S, the reanalyses ensemble mean indicated that the PPT trends increased 60%, from 8.2 x 10− 3 to 1.3 x 10− 2 mm day− 1 decade− 1, when comparing the previous period (1900–1979, “before 1980”) with the contemporary (1980–2014, “after 1980”); The multi-model mean captured a sevenfold acceleration in PPT trends from the “before 1980” to the “after 1980” period (from 2.1 x 10− 3 to 1.5 x 10− 2 mm day− 1 decade− 1). However, PPT changes were spatially heterogeneous in the study area. While a general increase occurred south of 60° S, the western West AIS and the Ross Sea regions became dryer. We also analyzed the Southern Ocean's sea surface temperature (SST) and atmospheric circulation, two principal modulators of the Antarctic PPT. We found that PPT in Antarctica throughout 1900–2014 was primarily determined by changes in the atmospheric circulation rather than variations in the Southern Ocean's SST.