Climate Responses to Volcanic Eruption Clusters in the North Atlantic Under Different Boundary Conditions

Volcanic eruptions release aerosols into the stratosphere, which can trigger a wide range of climate responses across different temporal and spatial scales. However, the physical processes through which volcanic forcing leads to long-term global and regional cooling remain inadequately explored. Specifically, the climate responses following a series of intense volcanic eruptions before the Holocene remain insufficiently understood. The conditions during such past climates were vastly different from today’s, suggesting that potential amplifying feedbacks may also have differed. Using fully glacial, deglacial and pre-industrial boundary conditions, we conducted a suite of experiments with the Hadley Centre Coupled Model Version 3 and the Max Planck Institute's Earth System Model, forced with idealised volcanic eruption clusters, to investigate the long-term post-eruption sea surface temperature and sea ice responses in the North Atlantic. We find more intense and longer-lasting cooling in the subpolar North Atlantic in the fully glacial state compared to the other climate states. We explore the physical processes driving this cooling and how differences in the representation of upper-ocean conditions across the two climate models lead to model-dependent results.