Origins of Simulated Decadal Variability in the 1 Southern Ocean Region

Pre-industrial control experiments of 15 climate models are used to exam-9 ine decadal variability in the surface climate of Southern Hemisphere extra-10 tropics. We find the climate over the Southern Ocean exhibits large decadal 11 variability in all simulations, underscoring the distinctiveness of this region's 12 internal variability. In every model, decadal variations in surface tempera-13 ture and sea-ice are closely linked, possibly due to sea-ice albedo feedback. These similarities aside, we find there is two-to threefold intermodel spread 15 in the magnitude of the decadal variability. We apply linear stochastic the-16 ory to 'model the models', and find that it almost perfectly captures the mod-17 els' behavior. This exercise also reveals that most of the intermodel spread 18 in decadal variability can be attributed to differences in climate feedbacks.