Progress and barriers in understanding and preventing indirect land-use change

Climate change mitigation pathways have highlighted both the critical role of land-use emissions, and the potential use of biofuels as a low-emission energy carrier. This has led to concerns about the emission mitigation potential of biofuels, particularly related to indirect land-use change (ILUC). This arises when the production of biofuels displaces the production of land-based products elsewhere, either directly or via changes in crop prices, leading to indirect greenhouse gas (GHG) emissions. We review a large body of literature that has emerged on ILUC assessment and quantification, highlighting the methodologies employed, the resultant emission factors, modeled dynamics driving ILUC, and the uncertainty therein. Our review reveals that improvements in ILUC assessment methods have failed to reduce uncertainty and increase confidence in ILUC factors, instead making marginal improvements to economic models. Thus, while assessments have highlighted measures that could reduce ILUC, it is impossible to control or determine the actual ILUC resulting from biofuel production. This makes ILUC a poor guiding principle for land-use and climate policy, and does not help with the determination of the GHG performance of biofuels. Instead climate and land-use policy should focus on more integrated protection of terrestrial resources, covering all land-use-related products.