I’ve been looking into the MimiFUND code and noticed the following line in the
add_marginal_emissions! function (in the new_marginaldamages.jl file).
if year != nothing # pulse is spread over ten years, and emissions components is in Mt so divide by 1e7, and convert from CO2 to C if gas==:CO2 because emissions component is in MtC addem[getindexfromyear(year):getindexfromyear(year) + 9] .= pulse_size / 1e7 * (gas == :CO2 ? 12/44 : 1) end
Could you please explain why the pulse is spread over ten years, given that (at least to my understanding) FUND has an annual timestep? And also, why is the marginal pulse
pulse_size set to 1e7 metric tonnes (as the default value)? I’m guessing that this has something to do with 1e7 metric tonnes / 10 years = 1 Mt / year, but if the emissions pulse is 1 Mt / year, doesn’t this make the SCC value outputted by the model equal to the social cost of an additional Mt of emissions, rather than an additional metric tonne (t)? Or is there a unit adjustment somewhere in the code? I had a look but I couldn’t find anything, except for this line on the
v.loss[t, r] = (v.eloss[t, r] + v.sloss[t, r]) * 1000000000.0
…which is equally mysterious to me (why multiply by 1e9?)
Apologies if there’s a very obvious answer to this and thanks so much in advance for your help!