Projected late 21st century changes to the regional impacts of the El Niño-Southern Oscillation

As the dominant driver of interannual climate variability globally, any changes in the remote impacts of the El Niño-Southern Oscillation (ENSO) due to climate change are of considerable importance. Here we assess whether climate models from Phase 5 of the Coupled Model Intercomparison Project (CMIP5) project robust changes in ENSO’s regional temperature and precipitation teleconnections in the late 21st century, comparing the historical simulations (between 1950 and 1999) and high-emission future simulations (between 2040 and 2089). In order to quantify the importance of internal variability in these projected changes, we examine an ensemble of coupled model simulations from the Max-Planck-Institute Grand Ensemble (MPI-GE). Except for a few regions, the changes in ENSO’s temperature and precipitation teleconnections for most regions are not significant across the majority of models. Exceptions include consistent projected changes to temperature teleconnections over equatorial South America and East Africa, which are robust during La Niña events. Despite this, by assessing all regions together, a significant amplification of the temperature teleconnections is identified for La Niña events. Additionally, we find an overall projected weakening relative to the historical precipitation teleconnection when analysis is limited to regions that correctly reproduce the observed precipitation teleconnections. It remains unclear to what extent a change in regional ENSO teleconnections will be apparent, as it is clear that the changes in ENSO’s teleconnections are relatively small compared to the regional variability during the historical period.