Greenhouse gas emissions accounting is a method of calculating the amount of greenhouse gases (GHG) emitted by a region in a given time-scale. A National Emissions Inventory (NEI) measuring a country’s GHG emissions in a year is required by the UNFCCC to provide a benchmark for the country’s emission reductions, and subsequently to evaluate international climate policies such as the Kyoto protocol (although the original has now expired, extensions have been agreed) as well as regional climate policies such as the EU Emissions Trading Scheme (ETS).