David Bonan, Eduardo Blanchard-Wrigglesworth

Over the last 40 years observations show a teleconnection between summertime Pacific Ocean sea-surface temperatures and September Arctic sea-ice extent. However, the short satellite observation record has made it difficult to further examine this relationship. Here, we use 30 fully-coupled general circulation models (GCMs) participating in Phase 5 of the Coupled Model Inter-comparison Project to assess the ability of GCMs to simulate this teleconnection and analyze its stationarity over longer timescales. GCMs can temporarily simulate the teleconnection in continuous 40-year segments, but not over longer, centennial timescales. Each GCM exhibits considerable teleconnection variability on multidecadal timescales. Further analysis shows the teleconnection depends on an equally non-stationary atmospheric bridge from the subequatorial Pacific Ocean to the upper Arctic troposphere. These findings indicate the modulation of Arctic sea ice loss by subequatorial Pacific Ocean variability is not fixed in time, undermining the assumption of teleconnection stationarity as defined by the satellite record.