Time evolving parameterization for leaf properties

I've been in several discussions with groups asking about the feasibility of implementing time evolving parameterizations for CTSM that can be used for sensitivity tests in the model. For example, there seems to be good evidence that SLA and tissue stoichiometry changes under elevated CO2, but these are effectively fixed by values in the parameter file. Is this something that can be modified (e.g. as a function of CO2) at one place in the code, or would it have to be modified in individual modules where a parameter is used?

e.g. `cn_now = pftcon%leafcn + max(cn_slope*ln(CO2_now/CO2_base),0._r8)`

The plot below shows what the cn_now would be under elevated CO2, relative to a 350 ppm CO2 baseline with leafcn=25, for equations having cn_slope of 10, 15, 20


Interested to hear ideas about how this may be possible to explore.