concept

Global Change Assessment Model (GCAM)

Also known as: GCAM, GCAM model

Facts (13)

Sources

The potential land requirements and related land use change ... nature.com Nature Feb 3, 2021 13 facts

referenceIn the GCAM model equations, the subscript 'r' defines the region, 'p' defines the electricity penetration level, 'i' defines the technologies included in the solar- or bioenergy pathway, 'NL' defines non-land-occupying energy technologies, and 'i(l)' represents land-competing solar- or bioenergy, excluding rooftop solar, desert solar, dry scrubland solar, and bioenergy from waste or agricultural residues.

referenceWise et al. (2014) developed economic and physical modeling of land use in the Global Change Assessment Model (GCAM) 3.0, applying it to agricultural productivity, land, and terrestrial carbon.

referenceLand owners in the GCAM model choose between different land uses to maximize profit based on assumed yields, production costs, and commodity prices, using a logit model of sharing that accounts for local heterogeneity within each Agro-Ecological Zone and avoids extreme 'winner-takes-it-all' outcomes.

referenceIn the GCAM model, land use is divided into nodes where categories within the same node (such as corn, wheat, and bioenergy) are assumed to compete more directly with each other than with land uses in other nodes (such as forest or pasture).

referenceThe Global Change Assessment Model (GCAM), version 4.3, is a dynamic-recursive model with technology-rich representations of the economy, energy sector, and land use, linked to a climate model used to explore climate change mitigation policies such as carbon taxes, carbon trading, regulations, and accelerated deployment of energy technologies.

claimThe GCAM model incorporates pre-identified potential for PV and CSP capacity in Indian "wasteland" as an alternative to competitive land.

referenceIn the GCAM model equations, the parameter 'a' defines the CO2 emission factor per unit of electricity output of the alternative thermal generation technology, specifically natural gas.

referenceLand use and agricultural output in GCAM version 4.3 are calibrated for 18 pre-defined Agro-Ecological Zones (AEZs) that sub-divide geo-political regions based on climate zones (tropical, temperate, boreal) and crop growing periods.

claimThe impact of land management regimes in the GCAM model is calculated through off-model calculations because these regimes are assumed not to affect the allocation procedure of new solar energy.

claimThe study assumes that solar energy must be produced and consumed within the same geopolitical GCAM region due to the technical and geopolitical challenges of exporting or importing large shares of solar energy.

referenceThe GCAM model includes an additional module that links solar energy consumption with land use, allowing solar energy to compete with commercial land uses (crops, timber, intensive pastures) and non-commercial land uses (natural forest, grassland, scrubland).

claimA change in land cover in the GCAM model results in positive or negative Land Use Change (LUC) emissions, which are determined by the difference in assumed carbon stocks in vegetation and soil between the original and the new land use.

measurementThe GCAM model scenarios are run until 2050, with delayed effects on carbon release or sequestration in vegetation and soils abstracted until 2100.