A robust thermodynamic response of increased greenhouse gas forcing is
an expansion of the troposphere, which may decrease ozone concentrations
in the lower stratosphere and warm the tropopause. Yet, observations of
lower stratospheric ozone do not agree with model projections, and the
net effect of greenhouse gas forcing on the temperature structure of the
region between the tropical troposphere and stratosphere is unclear.
Here, I isolate the role of local ozone production in setting the height
of the cold point tropopause and the ozone concentrations above this
level. Increased ozone production near the tropopause following
tropospheric expansion will sharpen the vertical ozone gradient of the
lower stratosphere and decrease the distance between the top of the
troposphere and the cold point tropopause. This would suppress
tropospheric expansion and increase the water vapor concentration of the
stratosphere, which amplifies global warming and contributes to
stratospheric ozone destruction.