Climate State Dependent Response to Very Large Icelandic Effusive Volcanic Eruptions

Abstract Effusive volcanic eruptions have been common in Iceland throughout the Holocene with the largest ones happening prior to the industrial revolution. Such eruptions can affect climate through the formation of sulfate aerosols and subsequent impacts on clouds. As different atmospheric conditions modulate the cloud and climate responses to aerosol perturbations, a pre‐industrial effusive eruption might have different climate impacts were it to happen today or in the future. Here we use an Earth system model to simulate the surface climate response to Icelandic effusive volcanic eruptions under pre‐industrial, present day, and end of the 21st century climate conditions. For the last case, high anthropogenic greenhouse gas and aerosol emissions are assumed. We find that the climate state significantly modulates the climate response, especially in the Arctic where we model amplified surface warming during winter under pre‐industrial conditions and stronger surface cooling during summer in warmer climates.