In a Presidential Memorandum dated Jan. 7, President Donald Trump directed U.S. withdrawal from the U.N. Framework Convention on Climate Change (UNFCCC), among many other agreements and international organizations and programs. The Memorandum follows up on Executive Order 14199 of Feb. 4, 2025, which called for a State Department-led review of all international organizations and agreements to determine which are “contrary to the interests of the United States.” A related White House Fact Sheet, also dated Jan. 7, states that many of the bodies from which the United States will withdraw, which presumably include the UNFCCC, “promote radical climate policies.”
The announcement marks the latest in a series of steps under the two Trump administrations in which the United States has increasingly withdrawn from global engagement on climate. Although a future administration has options for rejoining the UNFCCC, this withdrawal is a further blow to global climate cooperation and more generally a demonstration of U.S. foreign policy volatility.
Background on the UNFCCC
The UNFCCC is the first global climate treaty; it was negotiated in the run-up to, and opened for signature at, the 1992 Rio Earth Summit. Its stated objective is to “prevent dangerous anthropogenic interference with the climate system.”
“Framework conventions” are generally designed to promote broad participation, including by leaving specifics for future elaboration. As such, the UNFCCC is quite general, setting out provisions on, e.g., relevant principles, mitigation and adaptation, finance, reporting on emissions, annual meetings of the “Conference of the Parties,” and future elaboration of the regime. At U.S. insistence, the emissions “aim” that applied to so-called “Annex I” Parties (which included the United States) and involved returning emissions to 1990 levels in the year 2000, was not legally binding.
The United States was an early ratifier of the UNFCCC, the Senate having approved it in 1992 by voice vote with no opposition. In signing the instrument of ratification, President George H.W. Bush deemed the agreement the “first step in crucial long-term international efforts to address climate change.”
The UNFCCC regime has evolved considerably since its entry into force in 1994:
- The Parties adopted the Kyoto Protocolin 1997, an agreement that the United States never sought to ratify due to, among other things, its failure to include commitments for developing countries whose emissions were growing.
- Building on the 2009 Copenhagen Accord, the Parties adopted a non-binding instrument in Cancun in 2010 that, among other things, quantified the UNFCCC’s objective of preventing dangerous interference with the climate, bolstered reporting and review, raised the profile of adaptation to climate impacts, and moved away from the Kyoto paradigm by covering developed and developing countries alike.
- Most consequentially, the Parties concluded the landmark Paris Agreementin 2015. It aims to limit global temperature rise to well below 2 degrees C (pursuing efforts to limit it to 1.5 degrees C) above pre-industrial levels and includes various mechanisms to promote the achievement of such goal. The backbone of the Agreement is the “nationally determined contribution,” i.e., each Party is responsible for designing its own emissions plan, which should become more ambitious with each five-year update.
The United States withdrew from the Paris Agreement under the first Trump administration. President Joe Biden rejoined the Agreement, signing the relevant instrument on day one of his administration in 2021. Shortly after taking office, Trump announced the second U.S. withdrawal from the Paris Agreement, which will take effect on Jan. 27.
Legal Aspects of U.S. Withdrawal From the UNFCCC
As a matter of international law, Article 25 of the UNFCCC permits States that have been Parties for more than three years to withdraw following one year of notice. U.S. withdrawal will therefore take effect one year after the United States submits its notice of withdrawal.
We assume that the United States will submit this notice shortly. (We note, however, that Trump’s Jan. 7 memorandum did not precisely say that the United States would formally withdraw. Rather, it described “withdrawal” as meaning “ceasing participation in or funding to” U.N.-affiliated entities, including the UNFCCC.) At the time of this writing, no notice of withdrawal has been posted by the Office of the U.N. Secretary-General, which serves as the treaty depository.
As a matter of domestic law, the mainstream legal view, as taken in the Restatement (Fourth) of Foreign Relations Law, is that the president may constitutionally withdraw the United States from a Senate-approved treaty where, as here, the withdrawal is lawful under international law and neither the Senate’s resolution of advice and consent nor a congressional law has put limits on withdrawal. The president’s power to do so has never been definitively resolved by the courts. In the 1979 case of Goldwater v. Carter (which involved President Jimmy Carter’s termination of a mutual defense treaty with Taiwan), a fractured Supreme Court declined to address this issue. In practice, however, presidents have exercised this unilateral withdrawal power, especially in the years since Goldwater. Examples of scholarly writings on the issue can be found here, here, here, here, here, and here.
Implications of U.S. Non-Party Status
The U.S. withdrawal from the foundational climate treaty is hugely symbolic, particularly given that the first Trump administration chose to remain a Party to the Convention and participated constructively in its proceedings. As a practical matter, however, the United States as a non-Party may not be discernibly different from how the United States functioned as a Party under the second Trump administration in 2025. In addition to not appearing at key meetings of Parties, the United States has been functioning as a de facto non-Party in other ways, including its notable failure in 2025 to submit a mandatory report on its greenhouse gas emissions.
As a non-Party, the United States will have the right to participate in Convention proceedings as an observer — without the right to vote or other rights associated with Party status. However, it seems unlikely that the administration will take advantage of such participation, given its lack of participation over the past year when the United States was still a Party.
While the world is familiar with U.S. flip-flopping on climate, given the history with respect to both the Kyoto Protocol and the Paris Agreement, withdrawal from the entire regime takes U.S. abdication of climate leadership to a new level. Many Parties may be relieved that the administration is not participating, given its current policies; however, in the longer term, U.S. absence could have a negative impact on the effectiveness of the regime and the willingness of other countries to take ambitious action.
Potential Rejoining
A future administration could have the United States rejoin the UNFCCC. This would also be necessary if the United States wishes to rejoin the Paris Agreement. (Article 20 of the Paris Agreement makes Party status in the UNFCCC a condition of joining the Paris Agreement.)
As a matter of international law, rejoining is straightforward. The UNFCCC provides in Article 23 that a State can become a Party 90 days after it deposits its instrument of ratification or accession. After doing that, the United States could rejoin the Paris Agreement, which per Article 21 would take 30 days after the deposit of its instrument.
As a matter of domestic law, there are multiple future pathways to rejoining the UNFCCC. In our view, the original Senate resolution of advice and consent remains in effect (unless repealed by the Senate) and provides the legal authority for rejoining by a future President. One of us (Sue) outlined this argument in 2017 in an unpublished paper, and the other of us (Jean) developed this position at length in a 2020 law review article. A future president could also seek a second round of advice and consent, ask Congress to approve rejoining, or potentially join the UNFCCC under his or her independent constitutional powers.
