Atlantic multidecadal variability amplifies decadal variability in the Kuroshio–Oyashio Extension region under global warming

The Kuroshio–Oyashio Extension is a major component of the Pacific western boundary current system, exerting strong influences on air–sea heat exchange, midlatitude climate variability, and marine ecosystem. However, its decadal variability under global warming remains uncertain, particularly regarding the role of remote Atlantic forcings. Here, using models with multicentury-long future climate outputs, we show intensified decadal sea surface height variability over the Kuroshio–Oyashio Extension under global warming, driven primarily by strengthened teleconnections from Atlantic multidecadal variability. Enhanced Atlantic multidecadal variability strengthens the atmospheric bridge, reinforcing wind stress curl anomalies over the central–eastern North Pacific. The resulting Ekman convergence anomalies amplify Kuroshio–Oyashio Extension variability via westward-propagating oceanic Rossby waves. In contrast, weakened Pacific decadal variability and increased upper-ocean stratification suppress this response. These findings suggest a growing role of Atlantic-driven teleconnections in shaping future North Pacific decadal variability, with implications for climate predictability under global warming. Intensified Atlantic Multidecadal Variability under global warming triggers stronger atmospheric teleconnections which amplify decadal variability in the Pacific Kuroshio–Oyashio Extension, as demonstrated by analyses of CMIP6 model simulations and future projections.