= Solution
A warmer <troposphere> does not imply a warmer <stratosphere>: increased <carbon dioxide> can cool the middle and upper stratosphere by enhancing infrared emission. One direct kinetic effect is slower temperature-dependent destruction in the <Chapman cycle>, tending to increase upper-stratospheric <ozone>. Two indirect chemical effects can have the opposite sign. If the entry <atmospheric cold trap> warms, it can admit more <water>; reaction with an <electronically excited oxygen atom> then supplies more of the <HOx family>, enhancing catalytic <ozone> loss. In cold polar air, changes in <water> and <temperature> can favour <polar stratospheric clouds>, whose surfaces activate halogen reservoirs and can enhance <ozone> destruction when sunlight returns. These are conditional pathways, not a universal sign for total <ozone>: cold-trap <temperature> and circulation, halogen abundance and altitude all matter. <Methane> oxidation can also supply stratospheric <water>.<Scientific Assessment of Ozone Depletion 2022 executive summary>[Executive summary: Stratospheric Temperature, water-vapour influences, and temperature-dependent polar ozone loss]{ref}
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