1. Now that the Paris Agreement has entered into force, would a US withdrawal in four years (under Article 28 PA) negate entry into force of the Agreement under international law, if the withdrawal means that the requirements for entry into force (under Article 21(1)) are no longer met? What — if any — is the legal rule in international law that says that once in force, it stays into force?
2. If the US withdraws from the UNFCCC, how early could this occur? And what would be the impact on its obligations under the Paris Agreement once that happens?
1. Article 55 of the Vienna Convention on the Law of Treaties states “Unless the treaty otherwise provides, a multilateral treaty does not terminate by reason only of the fact that the number of parties falls below the number necessary for its entry into force.” This provision is unambiguous and applicable in this case.
The Paris Agreement does not provide any exception to this general rule. Specifically, under Article 21 of the Agreement: “This Agreement shall enter into force on the thirtieth day after the date on which at least 55 Parties to the Convention accounting in total for at least an estimated 55 percent of the total global greenhouse gas emissions have deposited their instruments of ratification, acceptance, approval or accession.” Withdrawal from the Agreement is dealt with separately in Article 28 and there is no reference whatsoever in either provision to the withdrawal of a Party having any impact on the effectiveness of the Agreement for any other Party.
2. Under Article 25(1) of the UNFCCC, “[a]t any time after three years from the date on which the Convention has entered into force for a Party, that Party may withdraw from the Convention by giving written notification to the Depositary.”
Article 25(2) provides that “[a]ny such withdrawal shall take effect upon expiry of one year from the date of receipt by the Depositary of the notification of withdrawal, or on such later date as may be specified in the notification of withdrawal.”
The Convention entered into force for the United States on 21 March 1994. Thus, the United States may invoke Article 25(1) at any time and withdrawal so invoked will be effective in one year.
According to Article 25(3) of the UNFCCC, “[a]ny Party that withdraws from the Convention shall be considered as also having withdrawn from any protocol to which it is a Party.” Similarly, Article 28(3) of the Paris Agreement states, “[a]ny Party that withdraws from the Convention shall be considered as also having withdrawn from this Agreement.”
Thus, once withdrawal from the UNFCCC comes into effect, the Paris Agreement and any protocol thereto shall automatically cease to apply to the withdrawing Party. In conclusion, it is possible, in principle, for the United States to terminate application of the Paris Agreement (for the United States) by withdrawing from the UNFCCC without waiting three years, as it would be required to do if withdrawing only from the Paris Agreement directly. However, withdrawal from the UNFCCC is a far more dramatic step with consequences for a range of other protocols and processes apart from the Paris Agreement, and it is therefore less likely to occur.