United Kingdom

Historical emissions data for 1990–2020 were obtained from the UK Government (UK Government 2022h). Provisional emissions data for 2021 was also included to extend the time series to 2021 (BEIS 2022d). 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 emissions statistics rather than UNFCCC inventory emissions.

The UK’s 2030 NDC target of at least a 68% reduction below 1990 levels is expressed using 100 year global warming potentials (GWP100) from the IPCC’s Fifth Assessment Report (AR5) (UK Government 2022k). Consequently, we initially calculate the 2030 emissions implied by the UK’s NDC using AR5 GWPs. In addition, the UK Government has specified that the baseline will also use F-gas emissions from 1995. This alternative F-gas baseline is used when calculating the implied 2030 emissions level.

As the CAT presents all data across countries in GWP from the IPCC Fourth Assessment Report (AR4), the 2030 emissions implied by the NDC target in AR5 GWPs are then converted back into AR4 GWP. This is done by calculating a historical conversion factor from AR5 GWPs to AR4 GWPs, using historical data from 2019. This conversion factor can then be used to calculate the NDC in 2030 in AR4 GWPs.

The UK’s 2030 (NDC) and 2035 (Sixth Carbon Budget) emissions targets includes LULUCF emissions. This needs to be subtracted for comparability with other countries. We use projections from the CCC’s Sixth Carbon Budget to estimate LULUCF emissions in 2030 and 2035 (CCC 2020). While the Government’s approach to achieving the NDC and Sixth Carbon Budget differs somewhat from the CCC, there is strong alignment on afforestation pledges, and so LULUCF emissions will likely be closely aligned with the CCC’s projections, if these targets are to be met.

The UK’s 2050 net-zero target also includes both LULUCF and international aviation and shipping, which need to be removed. In the absence of long-term projections from the UK Government, we use the Sixth Carbon Budget to calculate LULUCF and international shipping emissions in 2050, while the high ambition scenario from the recent Jet Zero strategy is used to estimate aviation emissions in 2050 (CCC 2020, Department for Transport 2022b).

The UK Government has historically released annual reports which estimate the impact of all policies enacted as of that year, in the Energy and Emissions Projections (EEP). However, the latest assessment, the Net Zero Strategy baseline only considers policies enacted as of August 2019 (UK Government 2022f). Given the large range of policy announcements in the past three years, this projection represents a ‘baseline’ scenario, rather than a fully comprehensive current policy projection. The Government has yet to release a clear and transparent assessment of what impact its current policy portfolio will have on emissions reductions, and a recent court judgement has ordered the Government to provide this by March 2023 (Gayle 2022). This will be invaluable in scrutinising the adequacy of current climate policy in the UK.

To estimate current policy projections, we use the latest progress report from the UK’s Climate Change Committee (CCC 2022b). In this report, the CCC estimated the current UK policies on emissions. Policies are ranked as ‘credible’, displaying ‘some risks’ to delivery, displaying ‘significant risks’ to delivery, or ‘insufficient’.

To calculate the upper range of the current policies trajectory, we take the impact of all credible policies. These are policies where there are proven delivery mechanisms, a credible combination of public/private financing and clear timelines in place. These emissions savings come predominantly from the zero-emissions vehicle mandate to drive EV sales, the EV infrastructure strategy, and the Contracts for Difference scheme to support deployment of renewables in the power sector. To estimate the lower end of the current policy trajectory, we additionally include the impact of all policies ranked as displaying ‘some risks’. These are policies which are broadly credible, but where some adjustments may still be necessary for successful delivery. This includes policy to; drive uptake of zero emissions HGVs, to address price disparities in electric vehicle charging points, to decarbonise new homes (via the Future Homes standard), to support deployment of CCS and hydrogen in industry via the Industrial Decarbonisation and Hydrogen Revenue Support scheme, and policies to support flexible low-carbon power generation such as hydrogen.

The CCC estimates that in 2030, there are credible policies to cut emissions by 77 MtCO₂e, relative to the baseline in which no policies are introduced post-August 2019. Policies with some risks to delivery could cut emissions by a further 43 MtCO₂e in 2030. This gives an emissions level in 2030 of 293–331 MtCO₂e.

The conversion from AR5 to AR4 GWPs is done in the same way as when calculating the UK’s emissions targets, by calculating the ratio between AR5 and AR4 GWPs for 2019. Future LULUCF and international bunker emissions are taken from the UK’s Net Zero Strategy (UK Government 2022f).

The UK Government has yet to release a transparent assessment of how planned policies announced in recent documents, most notably the Net Zero Strategy, will reduce emissions. In the absence of such information, we are unable to calculate a planned policy projection with confidence. The UK Government is due to provide an updated Net Zero Strategy in March 2023, which should provide greater clarity on the estimated emissions impact of its current and planned policies. When this is released, it may be possible to include a planned policy projection in the assessment of UK climate action.

Current and planned policy projections are calculated by applying emissions reductions to the Net Zero Strategy baseline. This baseline already accounts for the impact of the COVID-19 pandemic on emissions via reduced economic activity and changes in travel patterns. It was therefore not necessary to further quantify the impact of COVID-19 on future emissions.

The CAT uses Global Warming Potential (GWP) values from the IPCC’s Fourth Assessment Report (AR4) for all figures and time series.