Climate-volcano feedbacks under global warming

Stratospheric volcanic aerosols can induce global cooling and other climatic effects on annual to multi-decadal timescales. Future global warming is projected to affect atmospheric processes governing volcanic plume dynamics and stratospheric aerosol transport. For instance, tropospheric warming driven by anthropogenic emissions leads to increased tropopause height and reduced tropical temperature lapse rate, resulting in enhanced atmospheric stratification. In addition, the Brewer-Dobson circulation is expected to accelerate under climate warming. These atmospheric changes can significantly influence volcanic plume rise dynamics, sulfate aerosol lifecycle, and the magnitude of radiative forcing. Despite growing recognition of climate-volcano feedbacks, few studies have examined their effects within fully-coupled Earth System Models.

In this study, we investigated the climate effects of future volcanic eruptions under different background climate states, including pre-industrial, low-end (SSP1-2.6) and high-end (SSP3-7.0) future anthropogenic emission scenarios. We first generated stochastic future eruption scenarios based on an array of bipolar ice cores, satellite measurements, and geological records spanning the past 11,500 years. We then simulated climate projections from 2015 to 2100 using three selected stochastic scenarios representing low-end, median, and high-end future volcanic activity within a plume-aerosol-chemistry-climate modelling framework (UKESM-VPLUME) with interactive volcanic aerosols. The UKESM-VPLUME framework couples a 1-D eruptive plume model (Plumeria) with the UK Earth System Model, enabling the simulation of injection height changes under different background climate states. Our results show that volcanic effects on stratospheric aerosol optical depth, effective radiative forcing, and global mean surface temperature are greater under climate warming for both tropical and extratropical eruptions. Our findings demonstrate the importance of accounting for climate-volcano feedbacks to understand long-term volcanic radiative forcing in future climates.