State-Dependent North Atlantic Response to Volcanic Eruption Clusters

Paleoclimate reconstructions suggest that clusters of volcanic eruptions may trigger sustained cooling events, but the underlying mechanisms and their potential dependence on the mean climate state remain poorly understood. Here, we investigate the climate response to an idealized eruption cluster using two coupled climate models under fully glacial, deglacial, and pre-industrial conditions. While the global mean temperature responses are largely climate-state independent, North Atlantic cooling is stronger under glacial conditions, especially in the Hadley Centre Model HadCM3. This response is primarily driven by a sustained weakening of the Atlantic Meridional Overturning Circulation due to increased surface buoyancy and sea-ice extent. However, the magnitude and duration of this response vary with climate state and model, due to differences in upper-ocean stability, convection zones, and sea-ice cover. Our results suggest that while volcanic clusters can induce intense cooling, they alone cannot sustain Younger Dryas-like climate shifts.