Volcanism, climate and the volcanic double event which kicked off the Middle Ages

Volcanic activity in and around the year 536 CE led to the coldest decade of the Common Era, and has been speculatively linked to large-scale societal crises around the world. Using a coupled aerosol-climate model, with eruption parameters constrained by recently re-dated ice core records and historical observations of the aerosol cloud, we reconstruct the radiative forcing resulting from a sequence of two major volcanic eruptions in 536 and 540 CE. Based on comparisons with current reconstructions of volcanic forcing over the past 1200 years, the decadal-scale Northern Hemisphere (NH) extra-tropical radiative forcing from this volcanic “double event” was larger than that of any known period. Earth system model simulations including the volcanic forcing are used to explore the temperature and precipitation anomalies associated with the eruptions, and compared to available proxy climate records. Finally, the climate model results are used to explore the probability of socioeconomic crisis resulting directly from the volcanic radiative forcing in different regions of the world.