Weakened Antarctic Dipole Under Global Warming in CMIP6 Models
Shujun Li, Wenju Cai, Lixin Wu
Abstract
Abstract The Antarctic dipole (ADP) depicts the leading mode of interannual variability over the Antarctic region in both sea ice and surface air temperature (SAT) fields. The ADP is superimposed on the long‐term climatic trends, modulating the response of the mean climate to external forcing by modifying the signal‐to‐noise ratio. The response of the ADP to greenhouse warming is unknown. Based on the Coupled Model Intercomparison Project Phase 6 models that capture main characteristics of the ADP, we find a robust reduction in variability of ADP under greenhouse warming. The warming‐induced sea ice loss limits the magnitude of ADP SAT variability through surface albedo feedback. The El Niño‐Southern Oscillation (ENSO) and the Southern Annular Mode (SAM) are two main triggering mechanisms of the ADP on interannual time scale. In a warmer climate, decreased variability of the SAM contributes to weakened ADP but increased ENSO variability plays an offsetting role.