Land-use - GCAM

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Alert-warning.png Note: The documentation of GCAM is 'under review' and is not yet 'published'!

Model Documentation - GCAM

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Model information
Model link
Institution Pacific Northwest National Laboratory, Joint Global Change Research Institute (PNNL, JGCRI), USA,
Solution concept General equilibrium (closed economy)GCAM solves all energy, water, and land markets simultaneously
Solution method Recursive dynamic solution method
Anticipation GCAM is a dynamic recursive model, meaning that decision-makers do not know the future when making a decision today. After it solves each period, the model then uses the resulting state of the world, including the consequences of decisions made in that period - such as resource depletion, capital stock retirements and installations, and changes to the landscape - and then moves to the next time step and performs the same exercise. For long-lived investments, decision-makers may account for future profit streams, but those estimates would be based on current prices. For some parts of the model, economic agents use prior experience to form expectations based on multi-period experiences.

Land use and land cover is determined within the larger GCAM modeling structure. The agriculture and land-use components of GCAM are coupled in code with other GCAM model components. Agricultural production, land use and land cover are determined for each of the 384 subregions based on land characteristics, technology availability, policy, and aggregate demand for goods and services produced on the land. The 384 subregions are determined by subdividing each of GCAM’s 32 global geo-political regions into the region's major water basins. Within each of these subregions, land is categorized into approximately a dozen types based on cover and use. Some of these types, such as tundra and desert, are not considered arable. Among arable land types, further divisions are made for lands historically in non-commercial uses such as forests and grasslands as well as commercial forestlands and croplands. A description of the treatment of agriculture and land use can be found in the documentation's section on land, as well as in more detail in the detailed land section. Information on land supply can be found at the Supply of Food, Feed, and Forestry page, and demand at the Demand for food, forestry, etc page. Land inputs can be found at the External Inputs to the Land Model page, and outputs at the Outputs from the Land Model page.