Accounting methods for international land-related leakage and distant deforestation drivers

International agricultural trade flows are increasingly important as distant drivers in global land-use changes, creating teleconnections between geographically separated locations of consumption and production. Land-use displacement and associated carbon emissions can undermine the effectiveness of land-use and climate policies, such as activities to reduce emissions from deforestation and forest degradation (REDD). Nevertheless, few accounting methods exist for international emissions leakage from land-use change, due to methodological and policy challenges. In this paper we review methods to quantify international land-use displacement and teleconnections through international trade. Weaknesses and strengths of those methods are assessed as well as the conclusiveness of results. We identify limitations and potential ways forward for the quantification of land-related leakage in general, while highlighting implications for REDD-leakage accounting in particular. Results show that land-related leakage assessments are facilitated by applying a weak leakage definition, without the requirement to demonstrate causal leakage effects. Suitable quantification approaches combine method elements such as economic modeling, trade-flow analysis, biophysical accounting and life-cycle assessments. Depending on the use of monetary or physical input data the results can change considerably. All reviewed methods face limitations such as uncertainties and data gaps in emission factors.