RESUMO
Estimates of land use change (LUC) attributable to the U.S. Renewable Fuel Standard (RFS) are critical for evaluation of the program's impacts on air and water quality, biodiversity, and soil quality. To improve our understanding of the range of published estimates, we reviewed 29 studies published since 2008 attributing domestic LUC to the RFS, updating previous comparisons and adding a growing number of empirical approaches to estimating biofuel-induced LUC. To identify principal reasons underlying differences in reported effects, we documented key attributes of studies' methods including spatial extent, time period, baseline scenario, policy influence, and LUC definitions. Across computable general equilibrium (CGE) and partial equilibrium (PE) economic simulation model studies we found a range of 0.01-2.45 million acres of net cropland expansion per billion-gallon increase in biofuels. Empirical approaches reporting national-scale estimates fall within this range, reporting 0.38-0.66 million acres per billion-gallon increase. Empirical studies had a much smaller range of estimates and were closer to PE approaches than CGE. Studies generally did not represent all the potential drivers of biofuel production, and instead reported projections reflecting a combination of RFS impacts and other influences. Additional refinements to the modeling and empirical approaches reviewed in this study can further improve our understanding of the land use change driven by biofuels and the RFS Program.
