The Clean Development Mechanism (CDM), which was established under the Kyoto Protocol, will continue for a transitional period under Article 6: CDM project transition: the Article 6 deal allows CDM projects to transition to the 6.4 mechanism if it is approved by the country where the project is located, and if the project meets the new rules, with the exception of rules on methodologies. Projects can continue to use the same old, and often deeply flawed, CDM methodologies until 31 December 2025, or the end of their current crediting period, whichever comes first. From 2026 on, they must be fully compliant with Article 6, but hundreds of millions of junk CDM credits could be rebranded as 6.4ERs, i.e. carbon credits under Article 6.4,  up until that date. Up to 2.8 billion credits could become eligible for issuance if all CDM projects were to transition. Use of CDM credits: CDM credits (known as CERs) from projects registered on or after 1 January 2013 can be used towards countries’ first nationally determined contributions  (which ends in 2030 for most countries). This could lead to the transition of 300 million CERs. No credits from the Kyoto Protocol’s Joint Implementation mechanism (ERUs) are eligible under Article 6. Overall, the CDM will eventually expire, even if there is no formal end date yet. It can no longer accept requests for registration, for crediting period renewals, or for issuance of CERs, relating to emission reductions from after 31 December 2020. However, in the meantime, it can inflict significant damage to the credibility of Article 6 and to efforts to achieve real-world emissions reductions. The CDM’s remaining funds will largely be repurposed for the future Article 6.4 mechanism.