This white paper synthesizes existing scientific data on greenhouse gas (GHG) emissions related to the production and expansion of biofuels. It is specifically focused towards assisting organizations that are developing sustainability standards for biofuels with the collection and interpretation of data. There are a number of organizations developing sustainability standards or guidelines for biofuels. The organizations vary in their composition, structure and objectives. Many are voluntary multi-stakeholder approaches and while some are not considering greenhouse gases within their guidelines or standards, others are developing methods to quantify these GHG emissions or they are interested in promoting practices that can reduce GHG emissions. This paper is based on peer-reviewed data and published GHG calculation methodologies and is principally focused on currently commercial biofuel production from sugarcane, corn, soy, rapeseed, palm oil and on future feedstocks (lignocellulosic material); switchgrass, miscanthus, agricultural and woody residues and short rotation coppice.