Changes in global teleconnection patterns under global warming and stratospheric aerosol intervention scenarios

Abstract

We investigate the potential impact of stratospheric aerosol intervention (SAI) on the spatiotemporal behavior of large-scale climate teleconnection patterns represented by the North Atlantic Oscillation (NAO), Pacific Decadal Oscillation (PDO), El Niño-Southern Oscillation (ENSO) and Atlantic Multidecadal Oscillation (AMO) indices using simulations from the Community Earth System Model versions 1 and 2 (CESM1 and CESM2). The leading empirical orthogonal function of sea surface temperature (SST) anomalies indicates that greenhouse gas (GHG) forcing is accompanied by increases in variance across both the North Atlantic (i.e., AMO) and North Pacific (i.e., PDO) and a decrease over the tropical Pacific (i.e., ENSO); however, SAI effectively reverses these global-warming-imposed changes. The projected spatial patterns of SST anomaly related to ENSO show no significant change under either global warming or SAI. In contrast, the spatial anomaly pattern changes pertaining to the AMO (i.e., in the North Atlantic) and PDO (i.e., in the North Pacific) under global warming are effectively suppressed by SAI. For the AMO, the low contrast between the cold-tongue pattern and its surroundings in the North Atlantic, predicted under global warming, is restored under SAI scenarios to similar patterns as in the historical period. The frequencies of El Niño and La Niña episodes modestly increase with GHG emissions in CESM2, while SAI tends to compensate for them. All climate indices' dominant modes of inter-annual variability are projected to be preserved in both warming and SAI scenarios. However, the dominant decadal variability mode changes in the AMO, NAO, and PDO induced by global warming are not suppressed by SAI.