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GTAP Resource #1839

"The GTAP Land Use Data Base and the GTAPE-AEZ Model: Incorporating Agro-Ecologically Zoned Land Use Data and Land-based Greenhouse Gases Emissions into the GTAP Framework"
by Lee, Huey-Lin

The paper describes the new GTAP land use (LU) data base constructed via the funding form the United States Environmental Protection Agency (US-EPA). The GTAP LU data base is the output from the collaboration between GTAP center, University of Wisconsin-Madison, and the Ohio State University. We also present the GTAPE-AEZ model, which illustrates how land use and land-based emissions can be incorporated in the CGE framework for Integrated Assessment (IA) of climate change policies.
In the GTAP LU data base, we follow the FAO fashion of agro-ecological zoning (FAO, 2000; Fischer et al, 2002) to identify lands located in 18 agro-ecological zones (AEZs)¡Xsix AEZs in three climatic zones (boreal, temperate, and tropical). Lands located in a specific AEZ have similar (or homogenous) soil, landform and climatic characteristics (temperature and moisture regime). The six AEZs range over a spectrum of length of growing period (LGP) for which their climate characteristics can support for crop growing. AEZ 1 covers the land of the temperature and moisture regime that is able to support length of growing period (LGP) up to 60 days per annum. On the other end of the LGP spectrum, lands in AEZ 6 can support a LGP from 270 to 360 days per annum. Crop growing, livestock breeding, and timber plantation are dispersed on lands of each AEZ of the six, whichever meets their climatic and edaphic requirements.
In the GTAPE-AEZ model, we assume that land located in a specific AEZ can be moved only between sectors that the land is appropriate for their use. That is, land is mobile between crop, livestock and forestry sectors within, but not across, AEZ¡¦s. In the standard GTAP model, land is assumed to be transformable between uses of crop growing, livestock breeding, or timber plantation, regardless of climatic or soil constraints. The fact is that most crops can only grow on lands that is under certain temperature, moisture, soil type, land form, etc.. The same concern arises for land use by the livestock and the forestry sectors. Lands that are suitable for growing wheat may not be good for rice cultivation alike, even under transformation at a reasonable cost. The introduction of the agro-ecological zoning in GTAP helps to clear up the counterfactual assumption in inter-sectoral land transition, and permit a sound presentation of sectoral competition for land.
In GTAP-AEZ, we associate methane (CH4) and nitrous oxide (N2O) emissions to their emitting sources (or drivers). For example, we link methane emissions from paddy rice cultivation to the land used in the paddy rice sector of GTAP-AEZ. We treat methane emissions as input to the paddy rice growing, and permit limited substitution of other input for emissions according to estimates of the marginal cost of abatement, following the approach of Hyman (2001).
GTAP-AEZ is currently a comparative static model and so is not suited to long run analysis of climate change policy. However, for purposes of illustration and analysis, we run a simulation in which U.S. seeks to cut its GHG emissions by 5%. We compare the results of two scenarios: (1) the tax is imposed only on CO2 emissions from fossil fuel combustion, and (2) the tax is imposed on CO2 from combustion, CH4 and N2O from all sources. Preliminary results show that the carbon tax in scenario (1) required to attain a 5% reduction in total GHG emissions of the U.S. is about USD$15 (in 1997 USD). On the other hand, the carbon tax in scenario (2) required to attain a 5% reduction in U.S. total GHG emissions is only USD$5. This conforms with empirical findings presented at a recent meeting of the Energy Modeling Forum (EMF) at Stanford University (EMF, 2003; study results scheduled to publish in a special issue of The Energy Journal in Fall 2004) where it was concluded that multi-gas mitigation helps to reduce cost of emissions abatement. The simulations are based on the new GTAP LU data base. Results associated with land transition between using sectors are currently under examination.

Resource Details (Export Citation) GTAP Keywords
Category: GTAP Application
2005 Conference Paper
Status: Published
By/In: Presented at the 8th Annual Conference on Global Economic Analysis, Lübeck, Germany
Date: 2005
Created: Lee, H. (5/20/2005)
Updated: Batta, G. (6/21/2005)
Visits: 6,794
No keywords have been specified.

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