Supporting Online Materials for: Global Land Use and Greenhouse Gas Emissions Impacts of Maize Ethanol: The Role of Market-Mediated Responses

With the recent adoption by the California Air Resources Board of California’s Low Carbon Fuel Standard, and USEPA’s Energy Independence and Security Act, greenhouse gas releases from indirect land use change triggered by crop-based biofuels have taken center stage in the debate over the role of biofuels in climate policy and energy security. This paper presents an analysis of these releases for US maize ethanol. Our analysis highlights the key role of market-mediated responses to biofuels mandates. Factoring these into our analysis reduces cropland conversion by 72%. As a consequence the associated GHG release estimated in our framework is just 800 g CO2 MJ -1y (27 g MJ-1 for 30 years of ethanol production). This figure is a quarter of the one previously published value. However, it is still large enough to eliminate the global warming mitigation benefits of most corn ethanol.