Impact of Future Volcanic Eruptions on Stratospheric Ozone

Due to the anthropogenic release of chlorine-containing chemicals such as chlorofluorocarbons into the atmosphere in the twentieth century, a large volcanic eruption occurring today would initiate chemical reactions that reduce the thickness of the ozone layer. In the future, when atmospheric levels of chlorine are reduced, large volcanic eruptions are instead expected to increase the thickness of the ozone layer, but important details relevant to this shift in volcanic impact are not well known. Here we use the AER-2D chemical transport model to simulate a Pinatubo-like volcanic eruption in contemporary and future atmospheres. In particular, we explore the sensitivity of column ozone to volcanic eruption for four different climate change scenarios over the remainder of this century and also establish the importance of bromine-containing very short-lived substances (VSLS) in determining whether future eruptions will lead to ozone depletion. We find that the ozone layer will be vulnerable to volcanic perturbation for considerably longer than previously believed. Finally, we consider the impact on column ozone of inorganic halogens being co-injected into the stratosphere following future explosive eruptions using realistic hydrogen halide to sulfur dioxide ratios.