UCI CTM model simulations used for deriving the spillover of tropospheric ozone into the stratosphere

The world has made great strides in phasing out the halocarbons that drive
ozone loss, such as the chlorofluorocarbons 11 and 12. While living with
the well-documented depletion of the ozone layer, we are now watching the
slow recovery (increase) of stratospheric ozone over this century after
our phaseout of halocarbon production and use. Projecting this recovery
date also depends on the impact of other changing greenhouse gases on
stratospheric chemistry as well as changes in tropospheric ozone. Both
observations and models identify tropospheric ozone as increasing due to
air-quality pollution in the lower atmosphere. Here, using a global
chemistry-transport model, we find that this ozone increase carries over
into the stratosphere at rates affecting the recovery expected from the
decay of atmospheric halocarbons. This process is inherently included in
our chemistry-climate models but is not diagnosed as such. The ozone
assessments need to consider that what happens in the troposphere does not
stay in the troposphere, complicating our interpretation of ozone changes
over this century.