Climate Impacts from Large Volcanic Eruptions in a High-resolution Climate Model: the Importance of Forcing Structure

Explosive volcanic eruptions have large climate impacts, and can serve as
observable tests of the climatic response to radiative forcing. Using a
high resolution climate model, we contrast the climate responses to
Pinatubo, with symmetric forcing, and those to Santa Maria and Agung,
which had meridionally asymmetric forcing. Although Pinatubo had larger
global-mean forcing, asymmetric forcing strongly shifts the latitude of
tropical rainfall features, leading to larger local precipitation/TC
changes. For example, North Atlantic TC activity over is enhanced/reduced
by SH-forcing (Agung)/NH-forcing (Santa Maria), but changes little in
response to the Pinatubo forcing. Moreover, the transient climate
sensitivity estimated from the response to Santa Maria is 20% larger than
that from Pinatubo or Agung. This spread in climatic impacts of volcanoes
needs to be considered when evaluating the role of volcanoes in global and
regional climate, and serves to contextualize the well-observed response
to Pinatubo. Data used for a paper of Geophysical Research Letters.