Climate impact of a hypothetical Mt. Agung like eruption in boreal autumn 2017

Abstract:

The likelihood of a large volcanic eruption in the future represents the largest uncertainty concerning the evolution of the climate system on the time scale of a few years; but also an excellent opportunity to learn about the behavior of the climate system, and our models thereof. It is still uncertain how predictable the response of the climate system to volcanic eruptions is and how strongly a volcanic perturbation could affect global and regional climate on seasonal-to-decadal time scales. These questions became recently very prominent in the context of decadal climate prediction, as in boreal autumn 2017 the likelihood of a large volcanic eruption was high. Increased seismic activity was observed from the Mt. Agung volcano (Bali, Indonesia), which started on August 10th, 2017 with and continued with intensity increasing over September and October and slowly declining in early November. The Mt. Agung volcano last erupted in 1963 with a VEI 5 eruption and an estimated SO2 emission of 6.5 Tg. It was one of the largest eruptions of the 20th century with an estimated global cooling of 0.1 °C to 0.4 °C in the aftermath of the eruption. The recent ongoing unrest of Mt. Agung raised the possibility of the effects of another climatic relevant eruption in 2017. To investigate the possible climate impact we have performed decadal climate forecasts with the German MiKlip prediction system for an artificial Agung-like eruption starting in October 2017. We have simulated the evolution of the volcanic aerosol and the related radiative forcing with the global aerosol model ECHAM5-HAM with high vertical resolution (L90) and internally generated QBO. The SO2 emission profile has been adapted from the 1963 eruption. In this contribution, we investigate the response of different climate variables, e.g. near-surface air temperature, precipitation and sea ice. We also discuss strategies how to be prepared for the next climate relevant volcanic eruption.