In 2025, the UK will set its seventh carbon budget, covering emissions up to 2042. The independent Climate Change Committee, the UK’s statutory advisory body on climate change, is due to publish advice on this budget in February.
What are carbon budgets?
Carbon budgets set a legally binding cap on the maximum level of emissions (‘the net UK carbon account’) for a period of five years. In effect, a carbon budget is the amount of carbon that the UK has available to ‘spend’ in a set time frame, like a personal budget for shopping.
Carbon budgets are set 12 years in advance through secondary legislation under the Climate Change Act 2008. The UK’s carbon budgets are being gradually reduced over time, with the aim of reaching ‘net zero’ carbon in 2050.
There have been six carbon budgets so far (covering 2008 to 2037), and the UK will set the seventh this year. These budgets are set out in the table below.
| Carbon budget | Year | Emissions | Percentage reduction |
|---|---|---|---|
| Carbon budget 1 (CB1) | 2008 to 2012 | 3,018 million tonnes of carbon dioxide equivalent (MtCO2e) | 26% reduction on 1990 levels |
| CB2 | 2013 to 2017 | 2,782 MtCO2e | 32% reduction on 1990 levels |
| CB3 | 2018 to 2022 | 2,544 MtCO2e | 38% reduction on 1990 levels |
| CB4 | 2023 to 2027 | 1,950 MtCO2e | 52% reduction on 1990 levels |
| CB5 | 2028 to 2032 | 1,725 MtCO2e | 58% reduction on 1990 levels |
| CB6 | 2033 to 2037 | 965 MtCO2e | 78% reduction on 1990 levels |
| CB7 | 2037 to 2042 | To be confirmed | To be confirmed |
What is the current carbon budget?
We are currently within carbon budget four (CB4). The UK has over-achieved emissions reductions across its first three carbon budgets, cutting emissions across multiple sectors to levels below the carbon budgets.
The independent Climate Change Committee has assessed that further action is needed to remain on track for the UK’s target of reaching net zero by 2050. The committee found that emissions reductions to date have largely come from the energy supply sector. It said that for CB4 and beyond, more than three quarters of the required emissions reductions will need to come from other sectors.
What changes do future carbon budgets contain?
The sixth carbon budget (CB6) was set in 2021. Following advice from the Climate Change Committee (CCC), CB6 is the first carbon budget to include emissions targets for the international aviation and international shipping sectors. However, the scope of the emissions targets for aviation and shipping has not yet been defined. The Environmental Audit Committee has called for the government to introduce legislation to define what counts as emissions from international aviation and international shipping.
As well as the carbon budgets, the UK has also made an international commitment through its ‘nationally determined contribution’ to the Paris Agreement, to reduce emissions by 81% from 1990 levels by 2035 (PDF). This is higher than the target set for CB6 (to reduce emissions by 78% from 1990 levels by 2037). The government has said that this target aligns with the ambition required to deliver CB6.
The seventh carbon budget (CB7) is due to be set in 2025, and must be set by June 2026. The CCC plans to publish advice to the government on CB7 in February 2025. CB7 will set the government’s target for emissions reductions up to 2042: eight years before 2050, the year that the UK has committed to reaching net zero.
How is progress measured?
The government set out its approach to meeting the carbon budgets in its Carbon Budget Delivery Plan in March 2023. In her speech on economic growth on 29 January 2025, the Chancellor committed to publishing a refreshed plan later in 2025.
The CCC is responsible for assessing progress against the carbon budget targets and publishes annual progress reports to Parliament. In its most recent report, the CCC found that the emissions reductions across most sectors need to significantly speed up to meet the UK’s climate targets in the 2030s.
For more information on this topic, see the Library research briefing The UK’s plans and progress to reach net zero by 2050 (September 2024).
About the author: Nuala Burnett is a senior researcher at the House of Commons Library specialising in Climate Change.
Photo by: Anne Nygård on Unsplash