Abstract

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.