Intrinsic Century-Scale Variability in Tropical Pacific Sea Surface Temperatures and their Influence on Western US Hydroclimate

Hydroclimate variability of the southwest United States (SWUS) is influenced by the tropical Pacific Ocean, particularly through teleconnection to El Niño/Southern Oscillation (ENSO), which is expected to be altered by climate change. However, natural variability in this teleconnection has not been robustly quantified, complicating the detection of anthropogenic climate change. Here, we use a linear inverse model (LIM) to quantify natural variability in the ENSO-SWUS teleconnection. The LIM yields realistic teleconnection patterns with century-scale variability in teleconnection strength comparable to simulations from the Last Millennium Ensemble project and the Climate Model Intercomparison Project Phases 5 and 6. The variability quantified by the LIM illuminates two aspects of our understanding of ENSO and impacts: the inherent statistics of the observable system can produce century-long periods of nonsignificant correlation, and detecting changes in ENSO-related hydroclimate variability is challenging in a changing climate.