Running magpie with different scenarios

[KeLiu7]

Dear magpie community,

I would like to run magpie under different scenarios. Should I only change the settings for the two main drivers of the model below?

cfg$gms$c09_pop_scenario <- "SSP2" # def = SSP2
cfg$gms$c09_gdp_scenario <- "SSP2" # def = SSP2

I also noticed that some other parameters also have scenario options. For example:

cfg$gms$c70_feed_scen <- "ssp2"
cfg$gms$c60_res_2ndgenBE_dem <- "ssp2"

If what I mentioned above is right, do I need to change them as well or keep the default setting (ssp2)? Thanks.

[abhimishr]

In case you mean different SSP scenarios, have a look at the setScenario function from the gms library.
Manually setting SSP scenarios by hand could be error-prone. A simple example to follow could be seen here.

We also have a scenario_config.csv file in the config folder. You can find a list of settings to be changed under every SSP scenario there.

[KeLiu7]

In case you mean different SSP scenarios, have a look at the setScenario function from the gms library. Manually setting SSP scenarios by hand could be error-prone. A simple example to follow could be seen here.

We also have a scenario_config.csv file in the config folder. You can find a list of settings to be changed under every SSP scenario there.

Thanks Abhimishr.

Yes, I do mean different SSP scenarios. For example, if I would like to output the food demand under different SSPs.

Should I only change the settings as below before running the model?

for(ssp in c("SSP1","SSP2","SSP3")) {

cfg$title <- .title(paste(ssp,"Ref",sep="-"))

cfg <- setScenario(cfg,c(ssp))

cfg$gms$c15_food_scenario <- paste0(ssp)

start_run(cfg, codeCheck = TRUE)

}

As population growth and GDP are the two main drivers of the model, I think it be enough that we just change the SSP scenario for the two variables. Is it right? Why have to set the SSP scenario for each output variable that we need?

The default scenario in cfg is SSP2 for many variables. Here, if I would like to output food demand under SSP3. I think we should set the scenarios for all variables relevant with food module as SSP3 as well? Is it reasonble that we set food demand under SSP3 but other variables are SSP2 in the model?

Thanks for your patience. Looking forward to your comments.

[abhimishr]

The code snippet you pasted in principle could work (I did not test it) but setScenario(cfg,c(ssp)) already takes care of setting the right switch for cfg$gms$c15_food_scenario so that line is not needed.

As population growth and GDP are the two main drivers of the model, I think it be enough that we just change the SSP scenario for the two variables. Is it right?

While this is true, you should always be careful of not setting for example a SSP3 food demand for SSP2 population and gdp development.

Why have to set the SSP scenario for each output variable that we need?

We do not need to, the scenario_config.csv file summarizes the places where SSP specific changes need to be made. You can either set them manually (not recommended) or just with setScenario like from the code snippet you pasted.

Is it reasonble that we set food demand under SSP3 but other variables are SSP2 in the model?

This will not be correct (conceptually at least). In case you want to set up a model run like this, you have to be careful and explicit in describing your scenario setup and model assumptions.

[KeLiu7]

Many thanks for your explanation.

Now I understand: If I would like to run MAgPIE under different SSPs, I just need to use the scripts below. No need to set different SSPs for specific places. Generally, SSPs should be consistent for all outputs and this could be realized with setScenario, right?

for(ssp in c("SSP1","SSP2","SSP3")) {
cfg$title <- .title(paste(ssp,"Ref",sep="-"))
cfg <- setScenario(cfg,c(ssp))
start_run(cfg, codeCheck = TRUE)
}

[abhimishr]

Indeed. From the code snippet you posted, I am not sure what .title does (maybe it is a function you defined in your script?)

Also for this to work, you would need to call the gms library at the beginning of your script and also load the default cfg object using source("config/default.cfg") before you call your for loop.

[KeLiu7]

Ah, .title refers to the name of different output folders. Here we run the model three times so we need to set the name for them.

Again, many thanks for your help!