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Thematic Guide to Integrated Assessment Modeling
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Land Use
Land use is important in integrated assessment for two reasons: anthropogenic changes in land use, particularly forest clearing for expansion of human settlement and agriculture, are important driving forces in global environmental change; and changes in the suitability of particular land for particular uses, with resultant effects on human welfare and induced shifts in spatial land-use patterns, are among the important impacts of climate change. (For more information on land use, see the CIESIN Thematic Guide on Land Use and Global Environmental Change.) Large-scale population growth and movement over the next century are likely to exacerbate multiple pressures on the land resource: demand for food and fiber will increase with growing populations, while demand may also increase for biomass production for energy, and for preservation of such environmental resources as biodiversity, soil, and wetlands. Important uncertainties include the extent to which required increases in food production can be attained through continued yield increases rather than expansion of land under cultivation, and the related questions of whether environmental concerns may limit further expansion of fertilizer or pesticide use.Land use and its change are closely related to questions of ecosystem dynamics and their change under changed environmental and climatic conditions. Most present integrated-assessment projects represent land use only in primitive form, typically through external estimates of greenhouse-gas emissions from land-use change, with no feedbacks from climate change. The most advanced treatment to date has been in the IMAGE 2.0 model, which models the interaction between agricultural demand and climate-induced changes in potential land-cover to project changes in land use on a fine spatial grid-scale, and calculates associated greenhouse-gas emissions (Alcamo, Kreileman, Krol, and Zuidema 1994). At present the relationships driving land-use change are simple and largely non-behavioral, but more sophisticated representations are planned for subsequent versions of IMAGE. For example, the next iteration will move from a reduced-form version of the BIOME model to the full version to model potential terrestrial vegetation.
Researchers at Battelle Pacific Northwest Laboratories (PNL) are developing representations of land-use change that seek to represent competition among potential land uses, and greenhouse-gas emissions. PNL's MiniCAM model will include simple representation of land-use allocation and emissions, while the PGCAM model will include detailed specification of agriculture, land-use, and water resources.
The next section is Atmosphere and Oceans.
