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Few of the numerous published studies of the emissions from biofuels-induced "indirect" land use change (ILUC) attempt to propagate and quantify uncertainty, and those that have done so have restricted their analysis to a portion of the modeling systems used. In this study, we pair a global, computable general equilibrium model with a model of greenhouse gas emissions from land-use change to quantify the parametric uncertainty in the paired modeling system's estimates of greenhouse gas emissions from ILUC induced by expanded production of three biofuels. We find that for the three fuel systems examined-US corn ethanol, Brazilian sugarcane ethanol, and US soybean biodiesel-95% of the results occurred within ±20 g CO2e MJ -1 of the mean (coefficient of variation of 20-45%), with economic model parameters related to crop yield and the productivity of newly converted cropland (from forestry and pasture) contributing most of the variance in estimated ILUC emissions intensity. Although the experiments performed here allow us to characterize parametric uncertainty, changes to the model structure have the potential to shift the mean by tens of grams of CO2e per megajoule and further broaden distributions for ILUC emission intensities.

Recent research has shed light on the cost-effective contribution that agriculture can make to global greenhouse gas abatement; however, the resulting impacts on agricultural production, producer livelihoods, and food security remain largely unexplored. This paper provides an integrated assessment of the linkages between land-based climate policies, development, and food security, with a particular emphasis on abatement opportunities and impacts in the livestock sector. Targeting Annex I countries and exempting non-Annex I countries from land-based carbon policies on equity or food security grounds may result in significant leakage rates for livestock production and agriculture as a whole. We find that such leakage can be eliminated by supplying forest carbon sequestration incentives to non-Annex I countries. Furthermore, substantial additional global agricultural abatement can be attained by extending a greenhouse gas emissions tax to non-Annex I agricultural producers, while compensating them for their additional tax expenses. Because of their relatively large emissions intensities and limited abatement possibilities, ruminant meat producers face the greatest market adjustments to land-based climate policies. We also evaluate the impacts of climate policies on livelihoods and food consumption in developing countries. In the absence of non-Annex I abatement policies, these impacts are modest. However, strong income and food consumption impacts surface because of higher food costs after forest carbon sequestration is promoted at a global scale. Food consumption among unskilled labor households falls but rises for the representative farm households, because global agricultural supplies are restricted and farm prices rise sharply in the face of inelastic food demands.

This paper reviews an analysis of land use change impacts of expanded biofuel production with GTAP-BIO computable general equilibrium (CGE) model. It describes the treatment of energy substitution, the role of biofuel by-products, specification of bilateral trade, the determination of land cover changes in response to increased biofuel feedstock production, and changes in crop yields – both at the intensive and extensive margins. The paper responds to some of the criticisms of GTAP-BIO and provides insights into the sensitivity of land use change and GHG emissions to changes in key parameters and assumptions. In particular, it considers an alternative specification of acreage response that takes into account the degree of land heterogeneity within agro-ecological zone (AEZ) for different AEZs and countries. The paper concludes with the discussion of alternative specifications of land mobility across uses employed in CGE models and the agenda for further research to narrow parametric and structural uncertainty to improve the model's performance.