Reply on RC1

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 Models (CESM1 and CESM2). The leading Empirical Orthogonal Function of sea surface temperature (SST) anomalies indicates that greenhouse gas 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 patterns pertaining to AMO (i.e., in the North Atlantic) and PDO (i.e., in the North Pacific) changes under global warming are effectively suppressed by SAI. For 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 increase with greenhouse gas emissions in the models, 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 and interdecadal variability mode changes induced by global warming are exacerbated by SAI, particularly in the Atlantic-based AMO.