El Niño–Southern Oscillation Teleconnections in a Warming Climate

The El Niño-Southern Oscillation (ENSO) is an irregular pattern of alternating warm and cool sea surface temperatures (SST) that originates in the tropical Pacific regulated by interactions between the ocean and the atmosphere. Its environmental and socioeconomic impacts are felt worldwide. Historical and Representative Concentration Pathway (RCP) 8.5 simulations from the Climate Model Intercomparison Project Phase 5 (CMIP5) were examined to assess changes to ENSO and its teleconnections in a future warmer climate. A pattern correlation between the observed regression of monthly precipitation onto the Niño 3.4 index and that in each model was first conducted to assess model fidelity in historical simulations. Six models were selected based on their ability to accurately simulate the observed ENSO precipitation pattern. Differences of composite anomalies of precipitation and geopotential heights between future and historical simulations were generated for strong warm events (>0.5 °C) . Results suggest that the ENSO SST strength and teleconnection amplitude may weaken in a future warming climate, while the models do not agree on the sign of the change in ENSO precipitation amplitude. This suggests that North America might be less impacted by ENSO variability in a warming climate, and extreme weather patterns in the U.S. may become less predictable than today on seasonal timescales. Plans to examine how changes in tropical static stability with climate warming regulate the weaker teleconnections will be discussed.