Temporal Evolution of the Bromine Alpha Factor in Future Atmospheres

The bromine alpha factor, a measure of the ozone-destroying efficiency of a bromine atom relative to a chlorine atom, is estimated to have a global-temporal average value of ~65 in the present-day stratosphere. Although the physicochemical composition of the stratosphere is evolving, benchmark projections of Equivalent Effective Stratospheric Chlorine (EESC) treat this number as temporally-invariant. Using a 2-dimensional chemical transport model with meteorology informed by ESM projections, we evaluate the bromine alpha factor as a function of greenhouse gas emission scenario and time, finding significant variance in the temporal evolution of bromine alpha factor between possible climate futures.