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Scottish Greenhouse Gas Emissions Uncertainties Report

Scotland Greenhouse Gas Inventory Uncertainties Project

The Scottish GHG inventory is used to report on progress against legislative commitments to reduce GHG emissions and to support the monitoring of Scotland’s transition to a low carbon economy. The inventory is an annual statistical publication and it provides essential information for policy makers to indicate the effectiveness of current policies, and where additional GHG mitigation measures may be targeted. The level of uncertainty associated with the estimates of emissions and removals provides essential information for policy makers to make informed judgements.

For some inventory sources, the uncertainty inherent within the emission estimates due to (predominantly) scientific uncertainty regarding emission factors (i.e. the magnitude of emissions or removals associated with a specific activity) are very high and this makes the analysis of progress to targets problematic and undermines confidence in the use of inventory data. This project has sought to address this problem by analysing the uncertainties for each gas and key source category in the Scottish inventory, assessing and presenting uncertainties at a detailed level, and identifying priorities for further work to reduce overall inventory uncertainties in future.

The research, led by Ricardo-AEA, has delivered a revised and updated inventory uncertainties model for Scotland, integrating information from the 2006 IPCC Guidelines for national GHG inventories and the UK GHG inventory uncertainty model. The updated model includes new functionality to enable analysis of the impacts of EU ETS emissions on overall Scotland GHGI uncertainty and to derive trend uncertainties since the reporting Base Year, and for the latest year trends (e.g. “2012-2013”). The model update also integrates new Scotland-specific uncertainty parameters and uncertainty distributions for key source categories.

The report sets out the range of sources of uncertainty in the Scottish inventory, indicating the significance of different causes of uncertainty (such as lack of data, use of emission estimation models to represent complex processes, measurement error) to help identify where further work could help to reduce uncertainties.

The outcome is a model that delivers more accurate and lower estimates of uncertainty for Scottish GHG emissions (11% uncertainty for 2013 emissions), and a narrower range of “Base year to latest year” GHG trends (-35%, within a -26% to -45% range).

A link to the full report can be found here