Historical emissions data were obtained from the ‘Final UK greenhouse gas emissions national statistics: 1990-2018’ (UK Government, 2020h). Provisional emission data for 2019 was also included (Department for Business Energy & Industrial Strategy, 2020a). The UK provides inventory data to the UNFCCC that includes emissions from Overseas Territories and Crown Dependencies, which are not covered by UK climate policy and are not included in government emission projections. For this reason, we have chosen to use national emission statistics rather than UNFCCC inventory emissions.
NDC and other targets
For the 2020 target, we took the average emission level across the five years of the UK’s third carbon budget and subtracted the projected level of removals from LULUCF in that year (UK Government, 2019f). LULUCF is projected to provide an accounting contribution of -16 MtCO2e in 2020. For comparability between countries, the CAT presents all targets excluding LULUCF.
For the 2030 target (NDC), we took the average emission level across the five years of the UK’s fifth carbon budget and subtracted the projected level of removals from LULUCF in that year (UK Government, 2019f). LULUCF is projected to provide an accounting contribution of -11 MtCO2e in 2030.
For the 2050 net-zero target, we took the upper and lower projections of the CCC’s LULUCF emissions in 2050 (Core Scenario and Further Ambition minus Energy crops, agroforestry & hedges) and added this to the zero emission baseline (Committee on Climate Change, 2019c).
Current policy projections
The current policy projections from 2018 to 2030 were obtained from greenhouse gas emission projections updated annually by the UK Government which were then harmonised to the latest historical and provisional (2018) data (UK Government, 2019f). The UK’s annual emission projection report presents projections considering future impacts of policy measures enacted as of July 2018 (For details of the policies included, see Annex D of the BEIS Updated Energy and Emissions Projections 2018 report) (UK Government, 2019g). The CAT assesses the policies contained in the ‘Existing Policies’ scenario.
Planned policy projections
In this update we have chosen not to include a planned policy pathway for the UK. At the time of publication, the UK Government’s 2020 annual emission projections had not yet been released, and we have therefore reverted to the 2019 projections. As this projection does not include the numerous policy announcements of the last 12 months, the planned policy projection (“reference scenario”) is only 4 MtCO2e lower than the current policy projection (“existing policies”). It was felt that including this alongside the two current policy projections amended for COVID-19-related GDP growth estimates would detract from the readability of the graph, while also providing a false sense of the extent of policy development.
Once the UK government’s 2020 emissions projections are released, the assessment will be updated, and the planned policy scenario will be included once more.
We applied a novel method to estimate the COVID-19 related dip in greenhouse gas emissions in 2020 and the deployment through to 2030. The uncertainty surrounding the severity and length of the pandemic creates a new level of uncertainty for current and future greenhouse gas emissions. We distil the emission intensity (GHG emissions/GDP) from the pre-pandemic current policy scenario and apply to it most recent GDP projections that take into account the effect of the pandemic.
To capture a wide range, we have used more than one GDP projection. For the Post COVID-19 current policies max scenario, we have used the 2020 and 2021 GDP growth rates in the UK Treasury’s July “Forecasts for the Economy: A Comparison of Independent Forecasts” (HM Treasury, 2020). For the Post COVID-19 current policies min scenario, we have used 2020 and 2021 GDP growth rates from the OECD’s “Economic Outlook No 107 - June 2020 Double Hit Scenario” (OECD, 2020). We then use the GDP growth rates until 2035 that were used as a basis for the original pre-pandemic current policy scenario.
We also considered 2020 and 2021 GDP growth projections from the IMF and the OECD Single Hit Scenario, but these fell within the range of those from the UK Treasury and the OECD Double Hit Scenarios, so were not incorporated into the analysis.
Global Warming Potentials
The CAT uses Global Warming Potential (GWP) values from the IPCC’s Fourth Assessment Report (AR4) for all figures and time series.