Welcome to the gcamland wiki!
The package can be installed directly from its github repository using the R
devtools package. From an R prompt, run the command:
Documentation on how to use
gcamland is found in the help pages associated with the packages. These can be accessed using the following command:
There are several ways to access
gcamland outputs, depending on how
gcamland was run. If you have run a single scenario,
run_model returns the results. Alternatively, you can write the outputs to disk as a
rds file using the
aVerbose = TRUE option for
run_model. If you have saved the outputs to disk, these can be exported to a
csv file using
or plotted using
If you have used
run_ensemble, all results are saved to as
rds files in the output directory automatically.
Modifying the future scenario information
Changes in land allocation in the future occur due to changes in yield or price of commodities. Both of these values can be easily changed from the current defaults by modifying their values in the
inst/extdata/scenario-data folder. Yield changes are currently input as productivity growth, measured in % per year. Prices are currently in 1975$/kg for most commodities and 1975$/m^3 for Forest, but could be input in any unit as long as it is consistent.
Modifying the initialization data
There are several modifications users may want to make to the initialization data, with differing degrees of difficulty. Some of these options are listed here:
- If you want to change the region to a different GCAM region, then you need to modify the
DEFAULT.REGIONconstant in the
- If you want to change the any of the inputs (e.g., land allocation, cost, production, logit exponent, etc.) without modifying the structure of the nest or the land types, then you simply need to modify the values in the input files (
csvfiles contained in the
- If you want to model a new region (e.g., individual country, state, subnational entity), you need to add the information for your region to each of the input files in the
inst/extdata/initialization-datafolder and modify the
constants.Rfile. Note that
gcamlandwill work for any region and regions do not need to be defined by geopolitical boundaries.
- If you want to change the land types, but keep the number general nesting structure (including number of levels and where managed and unmanaged land leafs exist), then you only need to update the information in the input files.
- If you want to restructure the nest, adding new levels, then you will need to modify the
setup.Rfiles accordingly. This is a more difficult change than the other options.
In all cases, the user must ensure that the initialization data is consistent, meaning that the area of the land leafs adds up to the total land area in a region AND that all necessary information is read in for each node and leaf.