Abstract

Volcanic eruption plumes reaching the stratosphere result in the formation of long-lived (1-2 years) sulfate aerosols, which interact with Sun and Earth radiation and alter the radiative balance of our planet. In particular, stratospheric volcanic aerosol forcing results in a net cooling of Earth’s surface. As CO2 concentration increases due to anthropogenic emissions, changing weather and climate may affect multiple processes that govern the climatic impact of volcanic eruptions. Will we experience increased or decreased volcanic cooling on a warming Earth? This will be the central question of the seminar. I will focus in particular on how the rise of volcanic plumes and the injection of sulfur gases into the stratosphere may be affected by ongoing climate change.

First, I will discuss the ability of simple (0D, 1D) volcanic plume models to predict volcanic plume heights. Such models commonly require empirical constraints for processes such as the turbulent entrainment of atmosphere into a volcanic column, and are subject to large uncertainties. I will show how recent laboratory experiments and a newly compiled database of eruption source parameters improve constraints and evaluation of volcanic plume models. I will explore the implications of this new work for the prediction of volcanic plume heights and the production of pyroclastic flows, and discuss future steps for producing datasets that will enable a better evaluation of volcanic plume models.

Second, I will use the same volcanic plume models along with climate projections, a volcanic aerosol forcing model, and past records of volcanic sulfur emission to investigate the potential effects of climate change on volcanic plume rise. I will show that reduced volcanic sulfur injections into the stratosphere are projected with ongoing climate change. A novel feedback hypothesis emerging from this work is that volcanic cooling may be reduced on a warming Earth. I will discuss future plans to investigate this feedback in the UK Earth System Model along with feedbacks that could affect different processes governing the climatic impacts of future eruptions.