Wales shifts carbon units to Paris Agreement from 5 Dec
From Friday 5 December 2025, Wales will count carbon units issued under the Paris Agreement when it balances its greenhouse gas ledger. Ministers have updated the Carbon Accounting (Wales) Regulations to replace Kyoto‑era credits with the UN’s Article 6.4 units. Members of Senedd Cymru approved the change on 2 December and the regulation was made on 3 December, coming into force on 5 December.
What changed and why? The amendment removes the Kyoto Protocol from the definitions and inserts the Paris Agreement. It says a carbon unit is now an Article 6.4 “emissions reduction” credit, and each unit is counted at one tonne of carbon‑dioxide equivalent when Ministers calculate the net Welsh emissions account. This keeps Welsh law aligned with current UN rules.
If you’re comparing frameworks for class, here’s the simple story. Under Kyoto (1997), countries used Certified Emission Reductions from the Clean Development Mechanism. Under Paris (2015), Article 6.4 sets up a new UN‑supervised crediting mechanism with stronger quality controls and safeguards against double counting, overseen by a Supervisory Body and underpinned by a central registry.
How Wales counts emissions. Wales uses a “net Welsh emissions account”: territorial greenhouse gases minus removals, adjusted by any credits or debits allowed in law. The legal target for 2050 is net zero-at least 100% below the 1990 baseline-set in 2021. Carbon budgets run in five‑year blocks and must be set to keep that long‑term target in sight.
Numbers to keep in your notes. The Welsh Government says the fourth carbon budget (2031–2035) is set at a 73% average reduction against the 1990s level, and the third budget’s offset limit is 0%-so it must be met entirely through action in Wales. Senedd Members approved these climate regulations on 2 December 2025.
What this does not do. Today’s update doesn’t start a new round of offset buying. It updates the definition so that, if credits are used in future, they are Paris‑era Article 6.4 units rather than Kyoto‑era ones. Whether any credits can be used at all is decided separately through the offset limit for each carbon budget-set at 0% for 2026–2030.
Why now. Ministers say aligning with the Paris Agreement keeps Wales consistent with international standards and improves transparency. They also confirm they sought and considered advice from the Climate Change Committee before laying the draft regulations, ahead of the 2 December vote.
Key term for class: Article 6.4 emissions reduction (A6.4ER). This is a UN‑issued credit for a verified cut or removal equal to one tonne of CO2‑equivalent. Each credit has a unique identifier in a UN registry and can be authorised by a host country for use in meeting targets, with rules to prevent double counting.
Key term in Welsh law: carbon unit. From 5 December 2025, a carbon unit under the Carbon Accounting (Wales) Regulations means an Article 6.4 emissions reduction. When Ministers add up the net Welsh emissions account, each unit is worth one tonne of CO2e.
What this means for you. If you teach or study climate policy, this is a clear example of how international decisions show up in domestic law. You can trace a line from UN rules on Article 6.4, to a Senedd vote, to the way Wales records progress toward net zero in its statutory carbon budgets.
Who decided and how. The regulation is made under powers in the Environment (Wales) Act 2016, laid in draft, scrutinised, and then approved by Senedd Cymru. The Deputy First Minister for Climate Change, Huw Irranca‑Davies, signed it on 3 December, and the Welsh Government has prepared a Regulatory Impact Assessment in line with its Code of Practice.
What to watch next. UN work on the Article 6.4 mechanism continues through the Supervisory Body and the development of the central registry. As those rules bed in internationally, watch how Wales sets any future credit limits and, more importantly, how domestic policies deliver real cuts year by year.