in some very warm runs in e.g. ssp585 beyond 2100, using ch4_method="Thornhill", the methane lifetime adjustment due to temperature can get large. This causes this line:
np.log(1 + temperature * ch4_lifetime_temperature_sensitivity)
to become negative in the log term if ch4_lifetime_temperature_sensitivity is negative and temperature is large. This tends to happen in ensemble members above 15 K. The likelihood of FaIR being a reliable model in such extreme warming is small and these sorts of projections should be used with caution anyway, but there should be a sensible minimum value for the methane lifetime that can be set in the call to FaIR that would override the calculation if this log term becomes too small or NaN.
in some very warm runs in e.g. ssp585 beyond 2100, using
ch4_method="Thornhill", the methane lifetime adjustment due to temperature can get large. This causes this line:to become negative in the log term if
ch4_lifetime_temperature_sensitivityis negative andtemperatureis large. This tends to happen in ensemble members above 15 K. The likelihood of FaIR being a reliable model in such extreme warming is small and these sorts of projections should be used with caution anyway, but there should be a sensible minimum value for the methane lifetime that can be set in the call to FaIR that would override the calculation if this log term becomes too small or NaN.