Enhanced Eastern Pacific ENSO‐Tropical North Atlantic Connection Under Greenhouse Warming. Issue 22 (17th November 2021) - Liu, Yi
Abstract: Sea surface temperature variability in the tropical North Atlantic has far‐reaching climate impacts, especially in causing weather extremes in the Atlantic Ocean‐rim countries. El Niño‐Southern Oscillation (ENSO) can drive the tropical North Atlantic warming/cooling via the trans‐basin atmospheric bridge mechanism, yet how this interbasin connection will respond to greenhouse warming is unclear. Here, we find an enhanced eastern Pacific ENSO‐tropical North Atlantic connection under greenhouse warming using the Coupled Model Intercomparison Project phase 5 (CMIP5) multimodel projections. This enhanced connection is attributed to the strengthened Pacific‐to‐Atlantic atmospheric bridge mechanism due to a faster warming in the tropical eastern Pacific than tropical Atlantic under greenhouse warming. Thus, ENSO‐induced anomalous tropical North Atlantic warming/cooling and its related weather extremes are expected to increase in the future. Plain Language Summary: Anomalous tropical North Atlantic warming/cooling can cause weather extremes in the Atlantic Ocean‐rim countries. El Niño‐Southern Oscillation (ENSO) is able to trigger tropical North Atlantic warming/cooling events through atmospheric teleconnection, which is projected to be enhanced in the future climate. As greenhouse warming continues, the eastern tropical Pacific warms faster than tropical Atlantic, which induces a strengthened Pacific‐to‐Atlantic atmospheric bridge, hence enhance the eastern Pacific ENSO‐tropical North Atlantic connection. This study suggests an increased frequency of ENSO‐induced tropical North Atlantic warming/cooling and associated weather extremes in a warmer climate. Key Points: The eastern Pacific ENSO‐tropical North Atlantic SST connection is projected to enhance under greenhouse warming Strengthened tropical and extratropical atmospheric bridges jointly contribute to this enhanced connection The enhanced eastern Pacific ENSO‐tropical North Atlantic SST connection is caused by the tropical Pacific‐Atlantic mean state change