However, more detailed assessments are needed in order to properly assess AFOLU's mitigation potential, the impacts on vulnerable production systems and groups, and the costs of implementation. It is a pre-requisite that practices optimized to reduce GHG emissions or sequester carbon should also protect the land tenure rights of small-scale producers and contribute to food security and climate change adaptation, particularly for the most vulnerable groups. On the economic side, options include positive incentives for farmers to provide and maintain carbon sinks, taxation of nitrogen fertilizer in countries where it is being overutilized, a measure which is already applied in some OECD countries to reduce nitrate pollution, and supply-chain initiatives that market food products with a low carbon footprint (Paustian et al., It has been estimated, using previous calculations and data from Bellarby et al. ( These approaches generally account for emissions from pre-chain inputs through to post-farm gate processing by including methane, nitrous oxide and C02 emissions, and fossil fuel use in food systems (e.g. Steinfeld etal., This can be compared with around 5.2 GtC02-eq generated by agriculture and around 4.9 Gt0O2-eq by forestry and land use change.