We analyze the climatic relationship between the North Atlantic and North Pacific ocean basins by cross-correlating their primary low-frequency climate mode indices, Atlantic Multidecadal Variability for the North Atlantic and the Pacific Decadal Oscillation and the Victoria Mode for the North Pacific. These cross-correlations are then tested to determine if a robust internal connection exists. We use three methods to do so: 1) a bootstrapping statistical significance method testing the maximum value of the observed cross-correlation, 2) sensitivity testing by varying the starting date and period length, and 3) using a multi-model large ensemble to compare nearly 300 unique realizations of this relationship across six models. Our results all support that the relationship is indistinguishable from noise and thus that no robust internal relationship exists between the North Atlantic and North Pacific ocean basins.

Previous studies have attempted to unravel possible connections between leading decadal to multidecadal climate modes in the North Atlantic and North Pacific ocean basins, the Atlantic Multidecadal Variability in the North Atlantic, and the Pacific Decadal Oscillation and Victoria Mode in the North Pacific. We use newly available climate model data and apply improvements to existing methods to rexamine relationships among the different modes. Our main tool is the Multi-Model Large Ensemble Archive, which includes 270 ensemble members and allows for isolation of the forced and internal components of climate variability. Our results suggest that any internal connections between these modes are indistinguishable from random noise. Further, external forcing is shown to affect each region in similar ways, suggesting that climate change could be an indirect link between the two basins, and can confound the interpretation of he relationship between the basins.