Abstract:Debates about biofuels tend to focus separately on estimates of adverse effects on food security, poverty, and greenhouse gas (GHG) emissions driven by land-use change (LUC). These estimates often rely on global agriculture and land-use models. Because models differ substantially in their estimates of each of these adverse effects, some argue that each individual effect is too uncertain to influence policy. Yet these arguments fail to recognize the trade-offs; much of the uncertainty is only about which adverse effects predominate, not whether adverse effects occur at all. Our analysis of the three major models used to set government policies in the United States and Europe suggests that ethanol policies in effect are relying on decreases in food consumption to generate GHG savings.