This document summarizes a study on the implications of biodiesel-induced land use changes for CO2 emissions. The study examined 12 case studies across tropical regions. The main findings were: 1) Converting high-carbon stock lands like peatlands or rainforests to biofuel production can result in "carbon debts" that may take decades or centuries to repay through CO2 savings from biofuel use. 2) The time needed to offset the carbon debt depends on the type of land converted and the yield of the biofuel crop. Oil palm generally had shorter repayment times than Jatropha or oil palm on peatlands. 3) Land use changes from biofuel production can neg