 Solution

In the upper stratosphere, cooling slows temperature-dependent odd-oxygen destruction, including $\mathrm{O}+{\mathrm{O}}_3\to 2{\mathrm{O}}_2$ and important catalytic reactions. With photochemical production otherwise fixed, the local steady ozone abundance tends to rise. This chemical response is one reason increasing carbon dioxide can enhance upper-stratospheric ozone while cooling that region. It is compatible with enhanced chemical depletion in cold activated polar air; the controlling regimes differ.^[ref]