Model simulations of the climate impacts of volcanic eruptions in a
future warming scenario
Abstract
Episodic volcanic eruptions are often either not considered in future
climate projections, or represented in terms of a constant volcanic
forcing. This conventional representation of volcanic eruptions in
climate models does not account for how climate change might affect the
dynamics of volcanic plumes and the stratospheric sulfate aerosol
lifecycle and, ultimately, volcanic radiative forcing. The height of
eruptive plumes is indeed sensitive to atmospheric conditions such as
stratification and the strength of wind. In addition, climate change
will affect tropopause height, the Brewer Dobson circulation and
stratospheric temperatures which all govern volcanic sulfate aerosol
cycle. A recent study showed that for tropical eruptions, these changes
would either lead to a dampening or an amplification of volcanic forcing
depending on the eruption intensity. In this study, to account for
volcano-climate interactions in future climate projections, we present a
new modelling approach through coupling a 1-D plume-rise model
(Plumeria) with an Earth System model (UKESM). In this approach, each
time a volcanic eruption of prescribed intensity (i.e., mass eruption
rate) and SO2 mass occur, atmospheric conditions simulated by UKESM are
passed interactively to Plumeria which then computes the corresponding
height of eruptive plumes. Volcanic SO2 is then injected at the same
height in UKESM stratospheric aerosol module. With this new methodology,
plume heights are consistent with the climate conditions simulated by
UKESM. Our study thus represents a first attempt to consider the impacts
of climate change on volcanic eruptions in an Earth System model, which
allows us to better evaluate the climate impacts of volcanoes under
global warming.