chemistry (and earth system) feedbacks

[chrisroadmap]

see https://acp.copernicus.org/articles/21/1105/2021/ table 15

forcing/feedback separation comes into play also. e.g. a warming that affects CH4 or ozone concentrations, is this a feedback or a forcing? (well, it is definitely a feedback, but how to treat it in FaIR - we would probably change the CH4 concentrations easily enough, but then when doing e.g. natural and anthropogenic forcing totals, it would be part of the anthro, but a feedback effect). Similar consideration for permafrost.

Maybe we need three categories of forcings:

• anthropogenic (e.g. emitted CO2 and methane from fossil and AFOLU, ozone forcing from emitted percursors)
• natural (solar and volcanic)
• earth system feedback (permafrost, chemical feedbacks)

Book-keeping this will be difficult.

[chrisroadmap]

• switch to add a Tg [specie] / K feedback. This may not be appropriate for permafrost, but it is appropriate for methane wetland feedback (see UKESM)