Do CMIP6 models agree on the climate response in Eurasian winter to major volcanic eruptions since 1850?

This study provides a comprehensive analysis of the climate response in Northern Hemisphere winter to major volcanic eruptions of the past, using multi-member ensembles of historical experiments of 15 models from the Coupled Model Intercomparison Project Phase 6 (CMIP6) and three reanalysis data sets. Focusing on the two largest historical eruptions of Krakatoa and Pinatubo, the results highlight a large model consensus on the strengthening of the polar vortex and an associated increase in surface temperatures over parts of Northern Eurasia in the CMIP6 multi-model mean in the first winter following the eruptions. This finding is consistent with models simulating a positive phase of the North Atlantic Oscillation. The responses of the surface temperatures and winds show hardly any dependence on the phase of the El Nino-Southern Oscillation. Our results further underline a strong influence of internal variability on the simulated near-surface responses to volcanic forcing, even in the case of these strong eruptions. Thus, separating the influence of internal variability from the forced response requires output from large ensembles of historical simulations.

Reference

Weber, L., Krüger, K., and Fiedler, S.: On CMIP6 model consensus for the climate response in Eurasian winter to historical volcanic eruptions, in revision.