Climate Change (Scotland) Act 2009 interim target amendment regulations 2023

Annex A - The GHG (greenhouse gas) Account

The annual Scottish greenhouse gas inventory is used to report progress against all emissions reduction targets under the 2009 Act. It is a regional disaggregation of the UK greenhouse gas inventory. The methods used to compile the UK and Scottish inventories are consistent with international reporting, and compilation of the inventory is governed by a rigorous quality assurance process, and is subject to third party scrutiny. Every year, greenhouse gas inventory methodologies are updated to reflect improvements in the underpinning science, data and modelling.

As highlighted in the CCC target advice, due to a significant contribution from the land use sector (including peatlands), emissions in Scotland are particularly susceptible to methodological changes in emissions accounting. Because of this, and in accordance with CCC recommendations, Scotland’s statutory emissions reduction targets are set on a percentage reduction basis against a 1990/95 baseline period. As estimates of baseline emissions are also affected by methodological changes to estimation methods, this approach is more robust to changes than emissions targets set on an absolute (MtCO2e) basis.

However, even with percentage targets, changes in estimation methodology could make near-term targets that were previously stretching but achievable become either significantly more difficult or easier to meet. To address this, Scotland uses a ‘GHG Account’ methodology, recommended by the CCC and accepted by the Scottish Parliament during the bill process for the Climate Change (Emissions Reduction Targets) (Scotland) Act 2019 when assessing whether targets have been met.

At the heart of the GHG Account methodology is the freezing of inventory methods (the scientific methods used for the measurement and estimation of emissions levels) between the time that target levels are set (or reviewed through independent advice from the CCC) and the time when target outcomes come to be reported. This ensures that performance is effectively measured on the methodology in place when the targets were set or last reviewed by the CCC.

To prevent the inventory and the GHG Account from diverging too significantly over time, the methodology for assessing performance against the legislated emissions targets is reset to the latest inventory method at least every five years. The targets are revisited at this time by the CCC to ensure they are still both feasible and stretching, despite the methodology changes, and are in line with the latest climate science.

This method is enshrined in the 2009 Act and means that, following receipt of the CCC’s target advice, reporting from the 2021 annual target will be based on the most up-to-date inventory methods used in the latest 1990-2020 Scottish inventory published in June 2022. This will include additional emissions associated with the historical drainage and rewetting of peatlands and the impact that such activity has had, and continues to have, on the level of net greenhouse gas emissions. While these emissions have been incorporated since the 1990-2019 Scottish inventory, the statutory methodology for calculating progress to Scotland’s emissions targets (the GHG Account) means they were not reflected in the calculation of the target outcome for the target years 2019 and 2020 as the methods used were based on the 1990-2016 Scottish inventory published in June 2018.