ozone temperature dependence on forcing is a feedback #172
Description
In fair, as in AR6, the ozone radiative forcing is the sum of ozone forcing contributions from precursor species and a temperature driven effect that accounts for the increased production of OH in warmer climates (a negative feedback on ozone forcing). By default this is -0.037 W m-2 K-1.
The temperature effect could be incorporated into the overall climate feedback (i.e. added to the physical feedback terms of clouds, water vapour, lapse rate, Planck and ice-albedo) rather than kept as a modification to the forcing. This would be the first member of the set of "chemistry" feedbacks in fair (BVOCs would be another). Another class of feedbacks could be "earth system", such as permafrost (though to the extent that permafrost release elevates CH4 and CO2 concentrations, we would want to track this, see below).
The question of how to deal with feedbacks is more fundamental. This would be more difficult for the methane lifetime feedback, which is not likely to be a constant W m-2 K-1 value for all scenarios (neither is the ozone forcing feedback, but there is no other evidence to suggest that it isn't linear), and we want to actively track the methane concentration. The carbon cycle feedbacks that dictate CO2 concentrations also fall into this category.