Population, Land Use, and Environment Research Directions (2005) / Chapter Skim
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PART II--PAPERS: 3 Global and Case-Based Modeling of Population and Land Use Change--Günther Fischer and Brian C. O’Neill
PART II--PAPERS: 3 Global and Case-Based Modeling of Population and Land Use Change--Günther Fischer and Brian C. O’Neill
Pages 51-83
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From page 53... ...
, which is aimed at analyzing the potential impacts of trade liberalization and increasing incomes on the agricultural sector and on the livelihoods of the rural population that depends on agriculture in China. GLOBAL MODELING OF LAND USE Global models of environmental change simulate links among demography, economic growth, technological development, policy, and environmental outcomes to assess the state of current knowledge, help set re 53
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. A new generation of global models was developed in the late 1980s and early 1990s under the label of integrated assessment, primarily to assess the climate change issue and future scenarios for food and agriculture.
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Not all models include all of these components, and the level of detail with which any single component is represented varies widely, but this scheme represents the overarching framework in which all integrated assessment models of climate change either explicitly or implicitly operate. These models are the primary tools informing estimates of how much greenhouse gas emissions from human activity might increase, and therefore how much climate might change, in the absence of emissions reduction policies (Nakicenovic et al., 2000)
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MARIA: Multi-regional Approach for Resource and Industry Allocation These models include all of those used to produce long-term scenarios of greenhouse gas emissions for the Intergovernmental Panel on Climate Change (IPCC; models are AgLU, AIM, ASF, IMAGE, MARIA) , as well as those used to produce scenarios of changes in future ecosystem goods and services for the forthcoming Millennium Ecosystem Assessment (MA; models are AIM, IMAGE, and IMPACT)
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, USA University Global Environmental Department System Institution Joint Pacific National (NIES)
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The spatial component allows a more detailed and realistic accounting for available land, its potential productivity, and the effect of future climate change on productivity. While a variety of approaches are taken by these global models to land use change in general, the role of population is conceptually similar across all models.
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scaled up by projected future population growth. Global models use exogenous population projections, typically scenarios produced by the United Nations, IIASA, or the World Bank.
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Use Comm. Biomass 1 N/A N/A forest Products Land and Forest Industrial Wood 1 N/A 1 agriculture Requiring a Animal Products 1111 2 3111 3 2 (composite Agriculture Crops 1 2 6 6 1 4 Commodities for Total Commodities 5 6 12 9 1 7 Demand of Use)
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13 exogenous Calculate demand income, Calculate multiregion region-specific income confirm former a to dairy general the uses demand production and basic e model land; 1 N/A N/A food foods insufficient the is exogenously, India forest from date the e 1 N/A 2 processed to encounter differ specified and available as is that India and such obtained e 2 N/A N/A and demand; demand income scenarios and on thus Union, China, requirements, in supply 1 6 3 documentation based use Soviet but model; land balanced bidirectional; 12 10 1 former module. separately is on supply indirect scenarios, the good.
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62 of a a 2050, to 2050 factor Role a production BLS age production population of as beyond population of Population None Total factor Same none Working population production Total factor yields given and but joint prices, on over costs prices, capital 2050, available exogenous uses, production based given and capital land of land, assumptions production through distribution and return costs yield potential labor, return yields, BLS Allocation as labor, alternative nonland Land Methodology Maximize probability for and Minimize available exogenous Same production Maximize calculated land, None grid Resolution implicit potential regions minute Models distributions 34 5 regions, regions regions regions Geographic 11 subregional yield 17 34 BLS: AEZ: latitude/longitude 12 Global of types) sectors, sectors Categories pasture, pasture, (crop, Summary biomass)
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Assess Policy Agricultural FARM (Future Resources IMAGE (Integrated to Greenhouse IMPACT (International for of Commodities Trade) MARIA (Multi-regional Approach Resource Industry
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Need for Spatially and Socially Explicit Analysis of China's Development The CHINAGRO project takes into account two prominent trends: China's increasing international trade relations as a result of its accession to the WTO and the change of dietary patterns due to rapid per capita income increases and fast urbanization. The project analyzes the impacts of these
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describes agricultural processing and supply of farm inputs; and (4) accounts for transportation costs in the economy.
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Population projections employ cohort methods, with fertility and mortality reflecting geographical features as well as a distinction between rural and urban cohorts. Although internal migration across provinces is currently dealt with in a scenario approach, the model includes sufficient geographical, demographic,
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The CHINAGRO welfare model is based on detailed geographical and statistical databases to make analysis and simulations with the CHINAGRO model adequate for the policy questions under consideration. CHINAGRO Welfare Model The CHINAGRO model divides China into 8 economic regions comprising of some 2,432 administrative units, mostly counties.
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Consumer preferences, geographical distribution of supply, and costs of trade and transportation jointly determine the resulting endogenous trade flows. The nonagricultural production and consumption of tradable commodities are modeled at the level of the 8 economic regions.
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It distinguishes regional markets and a world market for each commodity. Price differences between regional markets and the international market are explained from trade and transportation costs and, possibly, government-imposed margins (taxes, subsidies, trade quota)
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Farmgate Farmgate county 1 county S(r) FIGURE 3-2 Trade flows inside a region.
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We note that such a modular decomposition of the calibration process is essential for the future maintenance of this rather large model, as it makes it possible to keep database operations fully separate from the modeling work, while improvements in the database are in a transparent way transmitted to the model outcome and future replacements in specific model components can be implemented without requiring a complete new calibration. Moreover, initialization at a fully calibrated base year solution provides a large number of checks and clues for detecting data inconsistencies and programming errors during the debugging phase of model building and also speeds up model computations and solution finding (Keyzer and van Veen, 2004)
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Hence, in CHINAGRO, we operate two models in parallel: (1) a general equilibrium welfare model, in which intraregional trade is subject to fixed transportation costs for all net purchases and net sales of a county and (2)
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. Such regionally disaggregated population projections are needed for estimating regional food demand and regional labor supply.
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. The decomposition procedure can be enhanced and the precision of the results can be increased by drawing on information from supplementary models like statistics-based projections of regional birth rates, death rates, urbanization rates, and interprovincial migration.
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. A series of market-oriented institutional reforms has been or is expected to be launched in China to actively promote the urbanization process, because the Chinese government has realized the serious adverse consequences on urbanization and economic growth resulting from the former urban-rural segmented institutional regulations and therefore defined active promotion of the urbanization process as one of the five strategic priorities of China's economic development during the 10th Five Year Plan period.
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on aggregation in a spatial continuum. The transport flow model is a partial equilibrium welfare model, which maximizes money metric consumer utility minus transport costs and is subject to site-specific commodity balances.
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International trade plays only a limited role, and the country is so large that local production is reasonably well protected against foreign imports, which can enter at seaports. Sequential Downscaling Methods for Spatial Estimation of Production Values and Flows The analysis of global change processes requires the development of methods that deal in a consistent manner with data on a multitude of spatial and temporal scales.
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A downscaling method in this case has to achieve plausible allocation of aggregate national production values to individual spatial units, for example, pixels, by using all available evidence from observed or inferred geospatial information, such as remotely sensed land cover, soil, climate and vegetation distribution, population density and distribution, etc. These methods are especially interesting and valuable for integrating in a consistent manner geographical data with statistical sources and to provide information and fill data gaps for spatially explicit modeling approaches, such as the transport flow model and the spatially explicit agricultural production relations used in the CHINAGRO project.
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Global models take a range of approaches to modeling land use change, including general and partial equilibrium economic frameworks, as well as rule-based simulation modeling, and operate at a range of spatial scales, from only a few large world regions to models operating on a raster of several thousand grid cells. The treatment of demographics in these models is more uniform, generally limited to population size acting as a scale factor on demand for agricultural and forest products and as a measure of available labor force on the production side.
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Keyzer, and L Sun 2002 Estimation of Agricultural Production Relations in the LUC Model for China.
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2003a Using Gravity Constraints to Optimize Transport Flows in a Spatially Explicit Equilibrium Model. (Working Paper.)
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Parson, E.A., and K Fisher-Vanden 1997 Integrated assessment models of global climate change.
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United Nations Environment Programme 2002 GEO: Global Environmental Outlook 3. London, England: Earthscan.
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