Abstract

Antarctic climate in winter is known to be influenced, among other factors, by changes in radiative forcing and remote Pacific climate variability, but none explains the observed sea ice trend or Peninsula warming. Looking to the Tropical Atlantic, a leading mode of Sea Surface Temperature (SST) variability, the Atlantic Multi-decadal Oscillation (AMO), has been overlooked. We show that AMO related SST anomalies, particularly in the Tropical Atlantic, induce a positive phase response in the Southern Annular Mode, strengthen the Amundsen Sea Low, project onto the observed dipole-like sea-ice distribution between the Ross and Amundsen Seas, and contribute to Antarctic Peninsula warming. Support for these findings comes from analysis of observational and reanalysis data, and independently from atmospheric model simulations forced by specified SSTs. This study suggests that the Tropical/North Atlantic is important for projections of future climate variability of Antarctica, and has possible implications for the global thermohaline circulation and sea-level change.