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Land Use in Computable General Equilibrium Models: An Overview

Center for Global Trade Analysis, Department of Agricultural Economics, Purdue University, GTAP Working Papers 01/2008;
Source: RePEc

ABSTRACT *Chapter 1 of the forthcoming book "Economic Analysis of Land Use in Global Climate Change Policy," edited by Thomas W. Hertel, Steven Rose, and Richard S.J. Tol

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    ABSTRACT: Biofuels may make a substantial contribution to meeting the world’s energy needs. That contribution may come sooner and be greater if there is a strong climate policy to reduce greenhouse gases and biofuels can be produced in a way that minimizes greenhouse gas emissions. We investigate the land use implications of biofuels under different policy conditions using a computable general equilibrium model of the world economy that has been adapted to explicitly consider land use change. We find that to meet a substantial portion of the worlds liquid fuel needs a global area approximately equal to that of today’s cropland would be needed. As much as two-thirds of the land could come from intensification of existing land, especially pastureland. Conversion of forests and the loss of natural ecosystems and carbon dioxide emissions associated with land use change present a substantial risk. We also find that comparative advantage in biofuels likely rests in the tropics despite belief in the US that biofuels could be a domestic source of energy, freeing us from imports. An attempt to meet US fuel needs through a domestic biofuels program would likely mean the US would become a major food importer and would contribute to higher land and food prices in the US.
    Farm Foundation, Transition to a Bio Economy Conferences, Environmental and Rural Development Impacts Conference, October 15-16, 2008, St. Louis, Missouri. 01/2008;
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    ABSTRACT: In recent years there has been a flurry of activity aimed at evaluating the land use consequences of biofuels programs and the associated carbon releases. In this paper we argue that these studies have tended to underestimate the ensuing land use change, because they have ignored the role of irrigation, and associated constraints on cropland expansion. In this paper, we develop a new general equilibrium model which distinguishes irrigated and rainfed cropping industries at a global scale. Using the new model we evaluate the implications of land use change due to US ethanol programs, in the context of short run constraints on the expansion of irrigated cropland. Since irrigated area tends to offer a higher yield than its rainfed counterpart, this provides an upper bound on the change in cropland following biofuel expansion. We find that the biofuel-induced expansion in global cropland cover is about 16 percent larger when the irrigation constraint is imposed. This translates into a 21 percent increase in land use emissions due to US ethanol production. This estimate represents an upper bound, since irrigated area can be expanded over the medium run in many places around the world.
    Energy, Sustainability and Society. 01/2011; 3(1).

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