U.S. Withdrawal from the Paris Agreement: Process and Potential Effects
Congressional research reportApr 14, 2025
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U.S. Withdrawal from the Paris Agreement:
Process and Potential Effects
April 14, 2025
Congressional Research Service
https://crsreports.congress.gov
R48504
SUMMARY
U.S. Withdrawal from the Paris Agreement:
Process and Potential Effects
On January 20, 2025, President Trump issued Executive Order (E.O.) 14162, in which Section
3(a) provided direction to the U.S. Ambassador to the United Nations (UN) regarding
withdrawing the United States for a second time from the “Paris Agreement under the United
Nations Framework Convention on Climate Change” (PA). Some Members of Congress have
expressed strong disapproval of the decision to withdraw from the PA, while others have voiced
approval for this action.
R48504
April 14, 2025
Jonathan D. Haskett
Analyst in Environmental
Policy
The PA is an internationally recognized treaty under the United Nations Framework Convention on Climate Change
(UNFCCC). The PA identifies specific climate mitigation temperature and emissions goals, among other provisions. The
United States joined the PA in 2016. Under President Trump the United States withdrew from the PA in 2020. Under
President Biden the United States rejoined the PA in 2021. In 2025, President Trump issued E.O. 14162, which states, “The
United States will consider withdrawal from the [Paris] Agreement and any attendant obligations to be effective immediately
upon this provision of notification.” PA Article 28 states that a 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.” In 2025, the UN Secretary General issued a depositary notification of the U.S. withdrawal from the PA.
The PA is the first UN climate treaty to include specific climate goals, stated as limiting global temperature increases “to well
below 2°C above pre-industrial levels and pursuing efforts to limit the temperature increase to 1.5°C above pre-industrial
levels.” The PA’s emissions goals are for emissions of greenhouse gases (GHGs) to peak as soon as possible, then to rapidly
decline, achieving a balance between GHG emissions and removals in the second half of the 21 st century.
The PA requires that Parties submit climate mitigation nationally determined contributions (NDCs) every five years. Parties
have sovereign discretion over their contributions. The PA established a range of market and nonmarket mechanisms to
reduce GHG emissions. Each Party to the PA is required, as appropriate, to engage in adaptation planning and the
implementation of adaptation actions. Parties to the PA agreed to undertake the first Global Stocktake in 2023 to assess
collective progress toward achieving the PA’s stated purpose and long-term goals.
The PA includes provisions on loss and damage associated with adverse effects of climate change. The PA did not establish
remedies for loss and damage. PA provisions state that developed country parties are obligated to provide financial resources
to developing countries with respect to both mitigation and adaptation as part of their obligations under the UNFCCC, and
other countries are encouraged to voluntarily contribute financial resources. PA provisions encourage countries to use a
“wide variety” of financial resources.
With regard to climate change mitigation, some researchers have examined the quantity and timing of GHG emissions and
the connection of such changes in GHG emissions with global temperature increases and the likelihood of achieving the PA’s
temperature goals. Researchers using varying techniques and different assumptions have found differing potential effects on
the U.S. economy as a result of withdrawal from the PA.
With regard to international climate cooperation, some observers have expressed concern that other countries will follow the
United States in withdrawing from the PA or will fail to maintain their ambition to reduce GHG emissions. As of April 11,
2025, no other country has withdrawn from the PA. A November 2024 synthesis report by the UNFCCC Secretariat (issued
prior to E.O. 14162), which examined the ambition for climate action in the NDCs, stated that the NDC ambition levels
reflected “a stagnation in aggregate NDC ambition level.” Some researchers have stated the concern that a U.S. withdrawal
from the PA could delay emissions reductions, precluding achieving the PA’s temperature goals. Other researchers hold the
point of view that U.S. withdrawal from the PA is unlikely to result in increased emissions.
Congress may choose to support policies such as emissions reductions, consistent with the PA’s goals; alternatively,
Congress may choose to repeal emissions reductions and other polices after the withdrawal decision. Congress may choose to
gather additional information on the effects of withdrawal by directing federal programs and agencies to study these effects
and report to Congress.
Congressional Research Service
U.S. Withdrawal from the Paris Agreement: Process and Potential Effects
Contents
Introduction ..................................................................................................................................... 1
The Paris Agreement (PA): Background ......................................................................................... 2
History of U.S. Participation in the PA ........................................................................................... 2
Joining the PA ........................................................................................................................... 3
First Withdrawal and Rejoining ................................................................................................ 3
Second Withdrawal ................................................................................................................... 3
Selected PA Provisions .................................................................................................................... 4
Temperature Goals .................................................................................................................... 4
Global Peaking of Greenhouse Gas (GHG) Emissions ............................................................. 5
Nationally Determined Contributions (NDCs) to Climate Change Mitigation ......................... 6
NDC Elements .................................................................................................................... 6
Timing of and Requirements for NDCs .............................................................................. 6
Voluntary Cooperation, Market and Nonmarket Mechanisms .................................................. 7
Adaptation ................................................................................................................................. 8
The Global Stocktake ................................................................................................................ 9
Loss and Damage .................................................................................................................... 10
Finance ..................................................................................................................................... 11
Potential Effects on Climate Change Mitigation ........................................................................... 12
Potential Domestic Economic Effects ........................................................................................... 13
Potential Effects on International Climate Cooperation ................................................................ 15
Congressional Interest and Options ............................................................................................... 16
Contacts
Author Information........................................................................................................................ 18
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U.S. Withdrawal from the Paris Agreement: Process and Potential Effects
Introduction
On January 20, 2025, President Trump issued Executive Order (E.O.) 14162, in which Section
3(a) provided direction to the U.S. Ambassador to the United Nations (UN) regarding
withdrawing the United States for a second time from the “Paris Agreement under the United
Nations Framework Convention on Climate Change” (PA).1 The United Nations Framework
Convention on Climate Change (UNFCCC) is a treaty ratified by the United States and other
countries in 1992 that provides the principal structure of collaboration on climate change.2 Parties
to the UNFCCC adopted the PA in 2015, outlining goals and a structure for international
cooperation to address climate change and its impacts.3 The PA, which entered into force on
November 4, 2016, sets specific temperature and emissions goals, among other provisions, in the
context of climate change mitigation.4 While E.O. 14162 references an immediate effect for the
PA withdrawal, the UN Secretary General issued a depositary notification of the U.S. withdrawal
from the PA effective January 27, 2026.5 Various Members of Congress have expressed an
interest in the U.S. withdrawal decision and its potential effects.6
This report describes the history of U.S. participation in and withdrawal from the PA, and
discusses the potential effects of the withdrawal. This report provides information on some treaty
provisions, including its temperature and emissions reduction goals, the financial obligations of
developed countries to developing countries, and reporting requirements, among others. This
report focuses on the implications of a U.S. withdrawal from the PA and does not address the
entirety of E.O. 14162.7 For example, in its discussion of the effects of the U.S. withdrawal from
the PA and the uncertainty around those effects, it focuses on the United States’ efforts to reduce
its greenhouse gas (GHG) emissions; it does not address the portions of E.O. 14162 related to
1 Executive Order 14162 of January 20, 2025, “Putting America First in International Environmental Agreements,” 90
Federal Register 8455, January 30, 2025, https://www.federalregister.gov/documents/2025/01/30/2025-02010/puttingamerica-first-in-international-environmental-agreements. The official designation for this agreement is the “Paris
Agreement” (PA). For example, that is how it is identified in the United Nations (UN) document stating that the
agreement had met the conditions for entry into force on October 5, 2016. See UN, “Paris Agreement Entry into
Force,” depositary notification C.N.735.2016. TREATIES-XXVII.7.d, December 12, 2015, https://treaties.un.org/doc/
Publication/CN/2016/CN.735.2016-Eng.pdf.
2 CRS Report R46204, The United Nations Framework Convention on Climate Change, the Kyoto Protocol, and the
Paris Agreement: A Summary, by Richard K. Lattanzio. President George H. W. Bush signed the instrument of
ratification and submitted it to the UN on October 13, 1992 (depositary notification C.N.148.1993).
3 Conference of the Parties to the United Nations Framework Convention on Climate Change (UNFCCC), “Adoption
of the Paris Agreement,” in Report of the Conference of the Parties on Its Twenty-First Session, Held in Paris from 30
November to 13 December 2015, Addendum, Part Two: Action Taken by the Conference of the Parties at Its TwentyFirst Session, FCCC/CP/2015/10/Add.1. Decision 1/CP.21, January 29, 2016 (hereinafter UNFCCC, “Adoption of the
Paris Agreement”).
4 Paris Agreement to the United Nations Framework Convention on Climate Change, December 12, 2015, T.I.A.S. No.
16-1104 (hereinafter UNFCCC, Paris Agreement); UNFCCC, “Key Aspects of the Paris Agreement,”
https://unfccc.int/most-requested/key-aspects-of-the-paris-agreement. The threshold for the PA to enter into force was
for at least 55 countries to ratify the agreement, accounting for at least 55% of global greenhouse gas (GHG) emissions.
5 UN, “Paris Agreement: United States of America—Withdrawal,” depositary notification C.N.71.2025. TREATIESXXVII.7.d, January 27, 2025.
6 Some Members have introduced resolutions opposing withdrawal from the PA; see H.Res. 68 and S.Res. 36. Some
Members have expressed support for withdrawal from the PA; see Rep. LaMalfa, remarks in the House, Congressional
Record, vol. 171, no. 14 (March 4, 2025), p. H954, https://www.congress.gov/congressional-record/volume-171/issue41/house-section/article/H954-2. See also Sen. Barrasso, remarks in the Senate, Congressional Record, vol. 171, no. 41
(March 4, 2025), p. S1468, https://www.congress.gov/congressional-record/volume-171/issue-41/senate-section/article/
S1468-1.
7 This report does not assess the implications of the other components of E.O. 14162, such as Section 3(b) related to
U.S. withdrawal “from any agreement, pact, accord, or similar commitment made under” the UNFCCC.
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ceasing financial commitments under the UNFCCC and the U.S. International Climate Finance
Plan. This report examines selected research on the potential effects of withdrawal from the PA on
(1) the climate system and global temperatures, (2) the U.S. domestic economy, and (3) efforts at
global cooperation to address climate change.8 The last section of this report includes
considerations for Congress and policy options associated with the January 20, 2025, withdrawal
announcement.
The Paris Agreement (PA): Background
The PA is one of the primary vehicles for international cooperation to address global climate
change.9 The PA is part of the UNFCCC, a framework of international cooperation on climate
change established in 1992.10 This section provides information on the framework of international
climate cooperation, its objectives, and the position of the PA within that framework.
In 2015, 195 governments attending the 21st Conference of Parties (COP) to the UNFCCC in
Paris, France, adopted the PA.11 The PA outlines goals and a structure for international
cooperation to address climate change and its impacts. The PA is a subsidiary agreement, an
international treaty that, by enhancing implementation of the UNFCCC, “aims to strengthen the
global response to the threat of climate change, in the context of sustainable development and
efforts to eradicate poverty.”12 The objective of the UNFCCC is as follows:
Stabilization of greenhouse gas concentrations in the atmosphere at a level that would
prevent dangerous anthropogenic interference with the climate system. Such a level should
be achieved within a time-frame sufficient to allow ecosystems to adapt naturally to climate
change, to ensure that food production is not threatened and to enable economic
development to proceed in a sustainable manner.13
The PA creates a structure for nations to pledge to abate their GHG emissions, adapt to climate
change, and cooperate toward these ends, including through the provision of financial and other
support.14
History of U.S. Participation in the PA
The United States is the only country that has joined and subsequently withdrawn from the PA.
Debate continues in the United States over whether and how the federal government should
address human-related climate change. Most scientists and governments accept that stabilizing
the concentrations of GHGs in the atmosphere and avoiding further GHG-induced climate change
8 This report discusses different findings and points of view on these potential effects. A full analysis of these topics is
beyond the scope of this report.
9 UNFCCC, Paris Agreement.
10 CRS Report R46204, The United Nations Framework Convention on Climate Change, the Kyoto Protocol, and the
Paris Agreement: A Summary, by Richard K. Lattanzio. President George H. W. Bush signed the instrument of
ratification and submitted it to the UN on October 13, 1992 (depositary notification C.N.148.1993).
11 UNFCCC, “Adoption of the Paris Agreement.”
12 UNFCCC, Paris Agreement, Article 2.1.
13 UNFCCC, Article 2, Objective.
14 UNFCCC, Paris Agreement, Articles 4.1, 7.1, 9.1, among others.
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would require concerted effort by all major emitting countries.15 This section presents a
chronology of U.S. participation in the PA.
Joining the PA
The PA entered into force on November 4, 2016.16 The United States deposited the instrument of
acceptance with the UN Secretary on September 3, 2016. By this action, the United States joined
the PA.17
First Withdrawal and Rejoining
On June 1, 2017, President Trump announced his intent to withdraw the United States from the
PA.18 The United States notified the UN Secretary General of its decision to withdraw on
November 4, 2019.19 The withdrawal took effect on November 4, 2020, in accordance with
Article 28 of the PA, which states that withdrawal takes effect one year after notification of
withdrawal.20 On January 20, 2021, President Biden signed the instrument of acceptance,
bringing the United States back into the PA, and on February 19, 2021, the United States rejoined
the PA.21
Second Withdrawal
On January 20, 2025, President Trump issued E.O. 14162 directing the withdrawal of the United
States from the PA.22 On January 27, 2025, the UN Secretary General issued a depository
notification of the withdrawal of the United States from the PA.23
Section 3(a) of E.O. 14162 directs the U.S. Ambassador to the UN to immediately submit formal
written notification of the U.S. withdrawal from the PA. The executive order goes on to state that
15 The UNFCCC states, “All States and regional economic integration organizations to which the UNFCCC is open
have expressed their consent to be bound by it.” UNFCCC, “What Is the United Nations Framework Convention on
Climate Change?” https://unfccc.int/process-and-meetings/what-is-the-united-nations-framework-convention-onclimate-change. See also Naomi Oreskes. “The Scientific Consensus on Climate Change,” Science, vol. 306, no. 5702
(2004), p. 1686.
16 UN, “Paris Agreement Entry into Force,” depositary notification C.N.735.2016.TREATIES-XXVII.7.d, December
12, 2015, https://treaties.un.org/doc/Publication/CN/2016/CN.735.2016-Eng.pdf.
17 UN Treaty Collection, Chapter XXVII: Environment, 7.d, “Paris Agreement,” December 12, 2015,
https://treaties.un.org/doc/Publication/CN/2016/CN.612.2016-Eng.pdf.
18 Trump White House, “Statement by President Trump on the Paris Accord,” June 1, 2017,
https://trumpwhitehouse.archives.gov/briefings-statements/statement-president-trump-paris-climate-accord/
19 U.S. Department of State, “On the U.S. Withdrawal from the Paris Agreement,” press release, November 4, 2019,
https://2017-2021.state.gov/on-the-u-s-withdrawal-from-the-paris-agreement/.
20 UNFCCC, Paris Agreement, Article 28.1, 28.2. See also UN Treaty Collection Depositary, Chapter XXVII:
Environment, 7.d, “Paris Agreement,” https://treaties.un.org/pages/ViewDetails.aspx?src=TREATY&mtdsg_no=
XXVII-7-d&chapter=27&clang=_en#7.
21 U.S. Department of State, “The United States Officially Rejoins the Paris Agreement,” press release, February 19,
2021, https://2021-2025.state.gov/the-united-states-officially-rejoins-the-paris-agreement/.
22 Executive Order 14162 of January 20, 2025, “Putting America First in International Environmental Agreements,” 90
Federal Register 8455, January 30, 2025, https://www.federalregister.gov/documents/2025/01/30/2025-02010/puttingamerica-first-in-international-environmental-agreements.
23 UN, “Paris Agreement: United States of America—Withdrawal,” depositary notification C.N.71.2025.TREATIESXXVII.7.d, January 27, 2025. The UN Secretary General is the depository of multilateral treaties under the UN, and the
UN Treaty Collection contains certified true copies of these treaties. For more information see UN, United Nations
Treaty Collection, https://treaties.un.org/Pages/Home.aspx?clang=_en.
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“the United States will consider withdrawal from the Agreement and any attendant obligations to
be effective immediately upon this provision of notification.”24 The depository notification in the
UN Treaty Collection states the following:
The action [Withdrawal] shall take effect for the United States of America on 27 January
2026 in accordance with paragraphs 1 and 2 of article 28 of the Agreement which read as
follows:
“1. At any time after three years from the date on which this Agreement has entered into
force for a Party, that Party may withdraw from this Agreement by giving written
notification to the Depositary.
2. Any 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.”25
Selected PA Provisions
The PA sets goals for addressing climate change and establishes international mechanisms for
furthering these goals; these include the establishment of the Conference of the Parties serving as
the meeting of the Parties to the PA (CMA), among other provisions.26 These and other selected
PA provisions are discussed below.
Temperature Goals
The PA is the first UN climate treaty to include specific climate goals for limiting global
temperature increases. The aim of these goals is to enhance the objective of the UNFCCC and
avoid increased climate change risks. The relationship of these goals to the UNFCCC and the
specific climate components of these goals are presented in this section.
The goal of the PA set out in Article 2.1 is to “strengthen the global response to the threat of
climate change, in the context of sustainable development and efforts to eradicate poverty,
including through specific steps.” It does this by “enhancing the implementation of the
Convention,”27 including the objective to prevent dangerous human interference in the climate
system.28 The UNFCCC does not state a specific temperature threshold for achieving this
24 Executive Order 14162 of January 20, 2025, “Putting America First in International Environmental Agreements,” 90
Federal Register 8455, January 30, 2025, https://www.federalregister.gov/documents/2025/01/30/2025-02010/puttingamerica-first-in-international-environmental-agreements.
25 UN, “Paris Agreement: United States of America—Withdrawal,” depositary notification C.N.71.2025.TREATIESXXVII.7.d, January 27, 2025.
26 The UNFCCC states describes the CMA as
The Conference of the Parties, the supreme body of the Convention, shall serve as the meeting of
the Parties to the Paris Agreement. All States that are Parties to the Paris Agreement are
represented at the Conference of the Parties serving as the meeting of the Parties to the Paris
Agreement (CMA), while States that are not Parties participate as observers. The CMA oversees
the implementation of the Paris Agreement and takes decisions to promote its effective
implementation.
UNFCCC, “Conference of the Parties Serving As the Meeting of the Parties to the Paris Agreement (CMA),”
https://unfccc.int/process/bodies/supreme-bodies/conference-of-the-parties-serving-as-the-meeting-of-the-parties-tothe-paris-agreement-cma.
27 UNFCCC, Paris Agreement, Article 2.1.
28 UNFCCC, May 9, 1992, S. Treaty Doc. No. 102-38.
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objective. To enhance the objective of the UNFCCC, the PA states a multifaceted temperature
goal:29
Holding the increase in the global average temperature to well below 2°C above preindustrial levels and pursuing efforts to limit the temperature increase to 1.5°C above preindustrial levels, recognizing that this would significantly reduce the risks and impacts of
climate change.30
Holding the increase in global temperatures to these levels would not avoid all climate change
risks and impacts. With each incremental increase in global temperatures there are detectable
increases in the frequency and intensity of some adverse climate impacts.31 Climate change
impacts have started to occur due to increased global temperatures, and climate impacts are likely
to increase further if global average temperatures exceed the 1.5oC goal.32 The PA does not
specify how temperature increase is measured; researchers using different datasets and
temperature baselines may find differing calculated values for global average temperature
increases.33
Global Peaking of Greenhouse Gas (GHG) Emissions
In addition to setting specific temperature goals, the PA states an aim of Parties achieving a
balance between GHG emissions and removals of GHGs from the atmosphere.34 Pursuant to PA
Article 4, the PA states some actions that Parties should take to achieve the agreement’s
temperature goals. Parties to the PA are to take actions to reduce GHG emissions to reach a
maximum or peak of GHG emissions as soon as possible, followed by rapid reductions in GHG
emissions.35 The aim is to achieve a balance between GHG emissions and GHG removals,
sometimes referred to as net-zero GHG emissions, by the second half of the 21st century.36
29 UNFCCC, Paris Agreement, Article 2.1.
30 UNFCCC, Paris Agreement, Article 2.2.
Intergovernmental Panel on Climate Change (IPCC), “Summary for Policymakers,” in Climate Change 2021: The
Physical Science Basis—Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental
Panel on Climate Change, 2021, Section B.2, states the following:
Many changes in the climate system become larger in direct relation to increasing global warming.
They include increases in the frequency and intensity of hot extremes, marine heatwaves, heavy
precipitation, and, in some regions, agricultural and ecological droughts; an increase in the
proportion of intense tropical cyclones; and reductions in Arctic sea ice, snow cover and
permafrost.
See also the U.S. Global Change Research Program (USGCRP), which stated, “With every additional degree of
warming, the United States is expected to see increasingly adverse consequences.” S. Hsiang et al., “Chapter 19.
Economics,” in Fifth National Climate Assessment, ed. A. R. Crimmins et al. (USGCRP, 2023); hereinafter USGCRP,
Fifth National Climate Assessment.
32 IPCC, “Summary for Policymakers,” in Climate Change 2021: The Physical Science Basis. See Also USGCRP,
“Chapter 19. Economics,” in Fifth National Climate Assessment. See also National Oceanographic and Atmospheric
Administration (NOAA), “What’s in a Number? The Meaning of the 1.5-C Climate Threshold: Do Impacts Start at
1.5°C of Warming?” https://www.climate.gov/news-features/features/whats-number-meaning-15-c-climate-threshold.
33 NOAA, “What’s in a Number? The Meaning of the 1.5-C Climate Threshold: When Do We Know We’ve Passed
It?” states: “The Paris Agreement does not specify how many years should make up this long-term trend, which dataset
should be used, and which time period makes up the pre-industrial period. That means different scientists, governments
and groups might come to different conclusions about when Earth passes this critical threshold.”
34 UNFCCC, Paris Agreement, Article 4.1.
35 UNFCCC, Paris Agreement, Article 4.1.
36 UNFCCC, Paris Agreement, Article 4.1. For more information on the concept of net-zero, see CRS In Focus
IF12753, Climate Change: What Are Net-Zero Emissions?, by Jonathan D. Haskett.
31
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Achieving such a balance would stabilize atmospheric GHG concentrations, an outcome
consistent with the UNFCCC’s objective.37
Nationally Determined Contributions (NDCs) to Climate
Change Mitigation
The PA establishes a process that obliges Parties to communicate—every five years—their
expected contributions to achieving the UNFCCC’s climate objectives as set out in Article 2.38
The PA refers to these periodic submissions as nationally determined contributions (NDCs).39
Although the PA requires this communication, the PA does not include mandatory targets and
timetables for Parties to reduce their GHG emissions.40 Article 4.2 of the PA obliges Parties to
take action to meet the NDCs, stating that “Parties shall pursue domestic mitigation measures,
with the aim of achieving the objectives of such contributions.”41 As of 2023, the United States
was the second-largest emitter of GHGs, after China.42 The U.S. NDC communicates “an
economy-wide target of reducing its net greenhouse gas emissions by 61-66 percent below 2005
levels in 2035.”43
NDC Elements
The NDCs reflect each country’s own national climate objectives and plans, including emissions
reduction goals, adaptation activities, and other elements.44 NDCs from developed countries are
expected to include economy-wide absolute emissions reduction targets, while developing
countries are encouraged to move to economy-wide emissions reduction depending on their
national circumstances.45
Timing of and Requirements for NDCs
Each Party to the PA is to communicate successive NDCs every five years, and each successive
NDC is to reflect an increasing ambition in its contribution to mitigating climate change.46 PA
Article 4 states the following:
37 UNFCCC, Article 2, Objective.
38 UNFCCC, “Adoption of the Paris Agreement,” paragraphs 13, 27. See also UNFCCC, Paris Agreement, Article 4.2,
4.9.
39 UNFCCC, Paris Agreement, Article 4.2.
40 UNFCCC, Paris Agreement, Article 4.2.
41 UNFCCC, Paris Agreement, Article 4.2.
42 European Commission, Joint Research Centre, M. Crippa et al., GHG Emissions of All World Countries, Publications
Office of the European Union, JRC138862, 2024.
43 UNFCCC, “The United States of America—Nationally Determined Contribution. Reducing Greenhouse Gases in the
United States: A 2035 Emissions Target,” https://unfccc.int/sites/default/files/2024-12/
United%20States%202035%20NDC.pdf. On December 19, 2024, President Biden announced a climate target for the
United States reducing economy-wide GHG emissions by 61%-66% from 2005 levels. Biden White House, “FACT
SHEET: President Biden Sets 2035 Climate Target Aimed at Creating Good-Paying Union Jobs, Reducing Costs for
All Americans, and Securing U.S. Leadership in the Clean Energy Economy of the Future,” December 19, 2024,
https://bidenwhitehouse.archives.gov/briefing-room/statements-releases/2024/12/19/fact-sheet-president-biden-sets2035-climate-target-aimed-at-creating-good-paying-union-jobs-reducing-costs-for-all-americans-and-securing-u-sleadership-in-the-clean-energy-economy-of-the-future/.
44 UNFCCC, Paris Agreement, Article 4.6.
45 UNFCCC, Paris Agreement, Article 4.4.
46 UNFCCC, Paris Agreement, Article 4.9, 4.3.
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Each Party’s successive nationally determined contribution will represent a progression
beyond the Party’s then current nationally determined contribution and reflect its highest
possible ambition.... A Party may at any time adjust its existing nationally determined
contribution with a view to enhancing its level of ambition, in accordance with guidance
adopted by the Conference of the Parties serving as the meeting of the Parties to this
Agreement.47
NDCs are not explicitly dependent on other countries’ actions. Changes in one country’s NDC do
not directly affect that of another country, as NDCs are to be determined by national
circumstances, although they are part of collective action under the PA to achieve the agreement’s
climate goals.48
The PA elaborates on a “transparency framework,” and all parties to the agreement are to
participate in this framework.49 In the transparency framework each party is to provide (1) “a
national inventory report of anthropogenic emissions by sources and removals by sinks of
greenhouse gases,” and (2) information to track progress on achieving NDCs.50 Each Party to the
PA is to provide “information related to climate change impacts and adaptation under Article 7
[on adaptation], as appropriate.”51 Developed countries must, and other countries should, also
provide information on financial, technology transfer, and capacity-building support provided to
developing country Parties in the transparency framework.52 The implementation and
achievement of NDCs is one of the reporting elements in the PA subject to technical expert
review.53
Voluntary Cooperation, Market and Nonmarket Mechanisms
Article 6 of the PA establishes mechanisms that allow parties to meet the goals of their NDCs
through the transfer of credits for mitigation activities.54 The PA establishes a range of market and
nonmarket mechanisms to accomplish such transfers and specifies that they are subject to
accounting standards to avoid double counting.55
Articles 6.2 and 6.4 of the PA include two distinct carbon market frameworks to allow these
transfers in the form of emission reduction credits.56 Articles 6.8 and 6.9 establish a nonmarket
47 UNFCCC, Paris Agreement, Article 4.3, 4.11.
48 UNFCCC, Paris Agreement, Article 4.4.
49 UNFCCC, Paris Agreement, Article 13.1.
50 UNFCCC, Paris Agreement, Article 13.7.
51 UNFCCC, Paris Agreement, Article 13.8.
52 UNFCCC, Paris Agreement, Article 13.9.
53 UNFCCC, Paris Agreement, Article 13.12.
UNFCCC, Paris Agreement, Article 6, multiple provisions. The IPCC states, “Climate change mitigation refers to
actions or activities that limit emissions of greenhouse gases (GHGs) from entering the atmosphere and/or reduce their
levels in the atmosphere.” M. Grubb et al., “Introduction and Framing,” in IPCC, Climate Change 2022: Mitigation of
Climate Change—Contribution of Working Group III to the Sixth Assessment Report of the Intergovernmental Panel on
Climate Change, ed. P. R. Shukla et al. (Cambridge University Press, 2022).
55 UNFCCC, Paris Agreement, Article 6.3, 6.4, 6.8, 6.9.
56 UNFCCC, Paris Agreement, Article 6.2, 6.4. Emission reduction credits allow the transfer of the outcomes of climate
mitigation activities from one party to another. The World Bank has stated the following:
An Emission Reduction Credit (ERC) represents a standard unit to measure an emission reduction
equivalent to one metric ton of carbon dioxide. Emission reductions credits can be generated
through either avoidance or removal projects. Avoidance involves activities that reduce emissions
by preventing the release of carbon dioxide or other greenhouse gases into the atmosphere.....
(continued...)
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process to support a range of objectives, including climate mitigation in other countries.57 The
UNFCCC states that a difference between the market-based mechanisms of Articles 6.2 and 6.4
and the nonmarket-based mechanisms of Articles 6.8 and 6.9 is that while the market-based
mechanisms may involve transfer of mitigation outcomes between parties, the nonmarket-based
mechanisms do not.58
Article 6.2 allows Parties to trade emissions reductions through bilateral or multilateral
agreements.59 Such transfers are subject to “corresponding adjustment” in which each Party must
account for the sale of the credit in its NDCs or emissions goals, to avoid double counting.60
Article 6.4 establishes a market-based mechanism that would allow for one Party to generate
carbon credits and sell them through a centralized system to another party that would use them to
meet its NDC.61 Article 6.4 creates a “supervisory body” accountable to the PA Parties to register
projects in a public database and issue carbon credits. The supervisory body met in Bhutan in
February 2025 and issued documents on the modalities of operation and the procedure of the
Article 6.4 mechanism registry.62 Both public and private entities would be eligible to participate
in the mechanisms established under Article 6.4.63
Article 6.8 establishes a nonmarket mechanism in which countries cooperate to achieve their
NDCs through approaches that are not transactions but rather the provision of other forms of
support, such as public and private funds and technology transfer.64
Adaptation
Each Party to the PA is required, as appropriate, to engage in adaptation planning and the
implementation of adaptation actions.65
The PA establishes a global goal on adaptation of
Enhancing adaptive capacity, strengthening resilience and reducing vulnerability to climate
change, with a view to contributing to sustainable development and ensuring an adequate
Removals refer to activities that pull carbon dioxide out of the atmosphere such as GHG
sequestration via reforestation or climate smart agriculture.
The World Bank Public Private Partnership Resource Center, “Emission Reduction Credits,”
https://ppp.worldbank.org/public-private-partnership/emission-reduction-credits.
57 UNFCCC, Paris Agreement, Article 6.8, 6.9.
58 UNFCCC, “FAQs on Non-market Approaches Under Article 6.8,” https://unfccc.int/process-and-meetings/the-parisagreement/the-paris-agreement/cooperative-implementation/faqs-on-non-market-approaches-under-article-68#What-isArticle-68-of-the-Paris-Agreement.
59 UNFCCC, Paris Agreement, Article 6.2.
60 UNFCCC, Paris Agreement, Article 6.2, 6.5.
61 UNFCCC, Paris Agreement, Article 6.4.
62 UNFCCC, Meeting Report: Fifteenth Meeting of the Article 6.4 Mechanism Supervisory Body, A6.4-SBM015,
https://unfccc.int/sites/default/files/resource/A6.4-SBM015.pdf. See also UNFCCC, “Modalities for Operation of the
Article 6.4 Mechanism Registry,” A6.4-SB008-AA-A16, https://unfccc.int/sites/default/files/resource/a64-sb008-aaa16.pdf; and UNFCCC, “Procedure Article 6.4 Mechanism Registry,” A6.4-SBM015-A12, https://unfccc.int/sites/
default/files/resource/A6.4-SBM015-A12.pdf.
63 UNFCCC, Paris Agreement, Article 6.4 (b).
64 UNFCCC, Paris Agreement, Article 6.8. See also UNFCCC, “Unlocking Climate Ambition: The Significance of
Article 6 at COP28,” https://unfccc.int/news/unlocking-climate-ambition-the-significance-of-article-6-at-cop28. See
also UNFCCC, “NMA Platform,” https://unfccc.int/process-and-meetings/the-paris-agreement/cooperativeimplementation/Article-6-8/nma-platform/main/non-market-approaches.
65 UNFCCC, Paris Agreement, Article 7.9.
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adaptation response in the context of the temperature goal referred to in Article 2 [of the
PA].66
The Parties to the PA established a global goal on adaptation and enhancement of adaptive
capacity.67 Parties to the PA are to engage in adaptation planning and implementation processes,
including the formulation of national adaptation plans.68 Such plans may include implementation
of adaptation actions, assessments of climate change impacts and vulnerability, and monitoring of
adaptation policies, programs, and actions.69
Parties are encouraged to submit and update periodically adaptation communications.70 No
timeline is specified.71 Regarding these communications, the PA states that they
Shall be, as appropriate, submitted and updated periodically, as a component of or in
conjunction with other communications or documents, including a national adaptation
plan, a nationally determined contribution.... 72
Information submitted by all parties regarding adaptation efforts (under Article 7) is subject to
technical expert review.73
The Global Stocktake
The PA includes provisions that oblige the Parties to assess their collective progress toward
achieving the purpose of the agreement.74 Article 14 of the PA directs that Parties shall
periodically take stock of PA implementation and collective progress toward achieving the PA’s
stated purpose and long-term goals, which include, among other things, (1) adhering to the PA’s
temperature goals; (2) increasing adaptive capacities, climate resilience, and low-GHG-emissions
development without threatening food production; and (3) aligning finance flows with low-GHGemissions and climate-resilient development.75 According to the UNFCCC Secretariat, the Global
Stocktake is the “key mechanism under the PA to ratchet up climate ambition and accelerate
implementation.”76
The PA states that the Parties agreed to undertake the first Global Stocktake in 2023.77 The Report
of the Conference of the Parties to the Paris Agreement on its fifth session, held in the United
Arab Emirates from November 30 to December 13, 2023, included the outcome of the first
66 UNFCCC, Paris Agreement, Article 7.1.
67 UNFCCC, Paris Agreement, Article 7.1.
68 UNFCCC, Paris Agreement, Article 7.9.
69 UNFCCC, Paris Agreement, Article 7.9.
70 UNFCCC, Paris Agreement, Article 7.10.
71 UNFCCC, Paris Agreement, Article 7.11.
72 UNFCCC, Paris Agreement, Article 7.11.
73 UNFCCC, Paris Agreement, Article 13.11.
74 UNFCCC, Paris Agreement, Article 14.1.
75 UNFCCC, Paris Agreement, Article 2.1(a)-(c), Article 14.
76 UNFCCC Secretariat, Synthesis Report: Views on the Elements for the Consideration of Outputs Component of the
First Global Stocktake, October 4, 2023, https://unfccc.int/sites/default/files/resource/SYR_Views%20on%20%20
Elements%20for%20CoO.pdf.
77 UNFCCC, Paris Agreement, Article 14.2. A description of the Global Stocktake and access to information on the
governance structure, components, and outcomes of the first Global Stocktake are available at UNFCCC, “Global
Stocktake,” https://unfccc.int/topics/global-stocktake.
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Global Stocktake.78 The Parties are to undertake a Global Stocktake every five years after the first
Global Stocktake.79
Loss and Damage
Loss and damage refers to a range of impacts that countries may sustain due to the adverse
impacts of climate change. Loss and damage has been a subject of discussion and debate within
the UNFCCC.80 The PA includes provisions on loss and damage that are part of the ongoing
negotiation and development process within the UNFCCC.81
Repeated scientific assessments have concluded that ongoing climate change would be
increasingly adverse, and potentially catastrophic, for a widening scope of populations and
ecosystems.82 Both slow-onset changes (e.g., desertification) and extreme weather events
contribute to an array of losses and damages.83 Negotiations on financial remedies to address
climate losses and damages have been contentious since the UNFCCC’s inception.84 The text of
the PA includes provisions on loss and damage, and these have been part of the basis for the
ongoing process of establishing a fund for loss and damage within the UNFCCC system.85
The PA includes provisions referring to loss and damage that are based on the recognition of
The importance of averting, minimizing and addressing loss and damage associated with
the adverse effects of climate change, including extreme weather events and slow onset
events, and the role of sustainable development in reducing the risk of loss and damage.86
The 19th UNFCCC Conference of the Parties (COP19) in Warsaw, Poland, established the
Warsaw International Mechanism (WIM) to address loss and damage associated with the effects
of climate change.87 Article 8.2 of the PA states that the WIM will be subject to the authority of
the CMA and may be strengthened and enhanced by the CMA.88
The negotiators agreed in Article 8 to explore cooperation and facilitation that could include early
warning systems, emergency preparedness, and comprehensive risk assessment and management,
78 UNFCCC, “Outcome of the First Global Stocktake,” FCCC/PA/CMA/2023/16/Add.1, 1/CMA.5, March 15, 2024.
79 UNFCCC, Paris Agreement, Article 14.2.
80 UNFCCC, “Loss and Damage Chronology,” https://unfccc.int/process-and-meetings/bodies/constituted-bodies/wim-
excom/chronology.
81 UNFCCC, Paris Agreement, Article 8.
82 IPCC, “Summary for Policymakers” in Climate Change 2022: Impacts, Adaptation and Vulnerability—Contribution
of Working Group II to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change, ed. H.-O.
Pörtner et al. (Cambridge University Press, 2022), pp. 3-33.
83 UNFCCC, Paris Agreement, Article 8.1. See also CRS In Focus IF12324, Loss and Damage Associated with the
Effects of Climate Change: Recent Developments, by Richard K. Lattanzio.
84 UNFCCC, Paris Agreement, Article 8.1. See also CRS In Focus IF12324, Loss and Damage Associated with the
Effects of Climate Change: Recent Developments, by Richard K. Lattanzio.
85 UNFCCC, Paris Agreement, Article 8.1. See also CRS In Focus IF12324, Loss and Damage Associated with the
Effects of Climate Change: Recent Developments, by Richard K. Lattanzio.
86 UNFCCC, Paris Agreement, Article 8.1.
87 UNFCCC, “Warsaw International Mechanism for Loss and Damage Associated with Climate Change Impacts,”
https://unfccc.int/topics/adaptation-and-resilience/workstreams/loss-and-damage/warsaw-international-mechanism.
87 UNFCCC, Paris Agreement, Article 8.2.
88 UNFCCC, Paris Agreement, Article 8.2.
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as well as improved resilience.89 The Parties to the PA did not adopt proposals that established
remedies or compensation for loss and damage.90
Negotiations on “new funding arrangements” to address loss and damage began, for the first time,
in November 2022 at the 27th UNFCCC Conference of the Parties (COP27) in Sharm el-Sheikh,
Egypt. While COP27 decided to establish “new funding arrangements” and “a fund,” these items
are largely procedural.91 The language in the Sharm el-Sheikh decisions does not connote new
funding arrangements to be “liability,” “compensation,” or “reparations.” The U.S. delegation and
others have consistently and successfully opposed inclusion of these concepts in negotiated
texts.92 In the following year at COP28, parties agreed to operationalize the loss and damage fund
to make it accountable to, and function under the guidance of, the governing bodies of the
UNFCCC and the PA.93
Finance
In a continuation of obligations under the UNFCCC, Article 9 of the PA states the obligation for
developed country Parties to provide financial assistance to developing countries with respect to
both mitigation and adaptation.94 Developing countries are encouraged to voluntarily provide
financial support.95
Developed countries are to provide biennial reporting of quantitative and qualitative information
on mobilizing climate finance, including, if available, levels of public finance.96 Select finance
provisions of the PA are described in this section of the report.
One of the sections of the PA that addresses financial aspects of the agreement, Article 9, states
the financial obligations that developed countries have to developing countries.97 Article 9
89 UNFCCC, Paris Agreement, Article 8.4.
90 UNFCCC, “Adoption of the Paris Agreement,” FCCC/CP/2015/10/Add.1, 1/CP.21, paragraph 51, states, “Agrees
that Article 8 of the [Paris] Agreement does not involve or provide a basis for any liability or compensation.”
91 UNFCCC, “Funding Arrangements for Responding to Loss and Damage Associated with the Adverse Effects of
Climate Change, Including a Focus on Addressing Loss and Damage,” FCCC/CP/2022/10/Add.1 Decision 2/CP.27,
paragraphs 2, 3, state that parties
2. Decide to establish new funding arrangements for assisting developing countries that are
particularly vulnerable to the adverse effects of climate change, in responding to loss and damage,
including with a focus on addressing loss and damage by providing and assisting in mobilizing new
and additional resources, and that these new arrangements complement and include sources, funds,
processes and initiatives under and outside the Convention and the Paris Agreement;
3. Also decide, in the context of establishing the new funding arrangements referred to in paragraph
2 above, to establish a fund for responding to loss and damage whose mandate includes a focus on
addressing loss and damage;
See also CRS In Focus IF12324, Loss and Damage Associated with the Effects of Climate Change: Recent
Developments, by Richard K. Lattanzio.
92 CRS In Focus IF12324, Loss and Damage Associated with the Effects of Climate Change: Recent Developments, by
Richard K. Lattanzio.
93 UNFCCC, “Operationalization of the New Funding Arrangements for Responding to Loss and Damage and the Fund
Established in Paragraph 3 of Decisions 2/CP.27 and 2/CMA.4,” FCCC/CP/2023/9−FCCC/PA/CMA/2023/9, 2023.
See also UNFCCC, “Fund for Responding to Loss and Damage,” https://unfccc.int/loss-and-damage-fund-jointinterim-secretariat; and UNFCCC, “Governing and Subsidiary Bodies,” https://unfccc.int/process-and-meetings/bodies/
governing-and-subsidiary-bodies.
94 UNFCCC, Paris Agreement, Article 9.1.
95 UNFCCC, Paris Agreement, Article 9.2.
96 UNFCCC, Paris Agreement, Article 9.5.
97 UNFCCC, Paris Agreement, Article 9.1.
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describes some sources of climate finance that can be used, states the reporting requirements for
developed countries, and describes the mechanisms for providing access to financial resources.98
The agreement states that developed country Parties should take the lead in mobilizing climate
finance and that the mobilized resources may come from a wide variety of sources—noting the
significant role of public funds.99 It adds that the mobilization of climate finance “should
represent a progression beyond previous efforts.”100 The scaled up financial support coming from
developed countries should be balanced in addressing climate change mitigation and climate
change adaptation.101
Developed country Parties are required to provide biennial reports on the provision of financial
resources to developing countries, including projected public financing.102 The Party’s
information on progress of efforts under Article 9 will be subject to multilateral technical expert
review.103 The PA uses the financial mechanism in place under the UNFCCC.104
Potential Effects on Climate Change Mitigation
This section examines the potential effects of a U.S. withdrawal from the PA on climate change
mitigation. Researchers and commentators have differing points of view and findings with respect
to the effect of U.S. withdrawal from the PA on the quantity and timing of GHG emissions. Some
researchers have also examined the connection of a U.S. withdrawal and changes in GHG
emissions with global temperature increases and the likelihood of achieving the PA’s temperature
goals. These analyses differ in their assumptions of what happens to emissions of the United
States and other countries after a U.S. withdrawal.
During the first Trump Administration, some researchers questioned whether withdrawal from the
PA would result in increased U.S. GHG emissions. The authors stated in 2018 that U.S. emissions
would be unlikely to increase with a withdrawal from the PA due, in part, to the shift that the
United States was already making in electricity generation from high-emissions sources of energy
(such as coal) to lower-emissions sources (such as natural gas and wind power).105 In 2017, other
researchers had argued the concern that a U.S. withdrawal from the PA could result in a delay in
implementation of emissions reductions by the United States, and other counties could follow
suit. These researchers stated that such a delay could preclude keeping the global temperature
increase to below 1.5oC-2oC above preindustrial global average temperatures, the temperature
goals of the PA.106
98 UNFCCC, Paris Agreement, Article 9.3, 9.5, 9.8.
99 UNFCCC, Paris Agreement, Article 9.3.
100 UNFCCC, Paris Agreement, Article 9.3.
101 UNFCCC, Paris Agreement, Article 9.4.
102 UNFCCC, Paris Agreement, Article 9.5.
103 UNFCCC, Paris Agreement, Article 13.11.
104 The Financial Mechanism of the UNFCCC includes as operating entities the Global Environment Facility (GEF)
and the Green Climate Fund (GCF), which assist developing countries to address climate change through the provision
of grants and other concessional financing for mitigation and adaptation activities. See also CRS In Focus IF10763,
U.S. International Climate Finance: A Primer, by Richard K. Lattanzio.
105 Johannes Urpelainen and Thijs Van de Graaf, “United States Non-Cooperation and the Paris Agreement,” Climate
Policy, vol. 18, no. 7 (2018), p. 839 (hereinafter Urpelainen and Van de Graaf, “United States Non-Cooperation and the
Paris Agreement”).
106 Benjamin M. Sanderson and Reto Knutti, “Delays in US Mitigation Could Rule out Paris Targets,” Nature Climate
Change, vol. 7, no. 2 (2017), p. 92.
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Other researchers have used simulation models and other types of analysis to estimate the effects
of a U.S. withdrawal from the PA on domestic and global GHG emissions. Researchers in 2017
analyzed what would happen if other countries maintained the global commitment to keeping the
global temperature increase to less than 2oC by further limiting their cumulative emissions of
GHGs following a U.S. withdrawal from the PA; the study assumed the withdrawal led to the
United States not fulfilling its NDC. In this study, U.S. emissions could increase beyond the
pledge identified in the first U.S. NDC, and the emissions of other countries in the study—China,
Japan, and the European Union (EU) member states—were assumed to correspondingly decrease
by 2030.107 For example, in a scenario in this study in which the United States withdrew from the
PA and its emissions were not reduced below 2005 levels, China, Japan, and the EU would have
to further reduce their emissions by about 5% each to keep cumulative emissions consistent with
achieving the 2oC climate goal.108
One 2024 study compared (1) the emissions reductions achieved by the PA if all countries were to
fulfill their NDC commitments active at the time of the study, and (2) the emissions reductions if
the United States were to follow its business-as-usual (BAU) emissions path rather than fulfill its
NDC commitment, while the other countries fulfilled their NDC commitments. The study, which
used a multisector structural trade model, found that “US non-participation in the Paris
Agreement lowers the achieved global emission reduction by more than a third (38.2).”109 The
scale of this impact is influenced by the United States’ role as a lead emitter and its ambitious
NDC target.
A complicating factor for evaluating the effects of U.S. withdrawal from the PA on U.S.
emissions is that withdrawal is just one factor shaping emissions. Other actions by the Trump
Administration and Congress could also affect the future trajectory of U.S. emissions. These
actions include changes related to domestic emissions regulations, as well as financial support—
such as grants, loans, and tax incentives—enacted in the 117th Congress and under
implementation during the Biden Administration. For example, the Trump Administration and the
119th Congress are considering reversing or altering some Biden Administration policies and
legislation enacted in earlier Congresses, such as provisions of P.L. 117-169, commonly referred
to as the Inflation Reduction Act (IRA). The IRA included provisions that may have financially
facilitated this shift to lower U.S. GHG emissions. For example, the IRA would be repealed under
proposed legislation (e.g., H.R. 191).
Potential Domestic Economic Effects
U.S. withdrawal from the PA could affect the U.S. economy. The previous U.S. withdrawal lasted
77 days, which limits the usefulness of observations from that period for informing how the U.S.
economy may respond to a second PA withdrawal. However, the debate around that withdrawal,
as well as U.S. participation in the PA, have led to various studies of the potential effects of PA
participation and withdrawal on the U.S. economy. These studies, which use different approaches
107 The United States’ first NDC provided for GHG emissions reductions of 26%-28% below 2005 levels by 2025. See
CRS Report R46945, Greenhouse Gas Emission Reduction Pledges by Selected Countries: Nationally Determined
Contributions and Net-Zero Legislation, by Kezee Procita and Claire M. Jordan.
108 Han-Cheng Dai et al., “The Impacts of U.S. Withdrawal from the Paris Agreement on the Carbon Emission Space
and Mitigation Cost of China, EU, and Japan under the Constraints of the Global Carbon Emission Space,” Advances in
Climate Change Research, Including Special topic on U.S. Withdraw from the Paris Agreement and Its Impacts, vol. 8,
no. 4 (2017), p. 226.
109 Mario Larch and Joschka Wanner, “The Consequences of Non-Participation in the Paris Agreement,” European
Economic Review, vol. 163 (2024), p. 104699.
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and assumptions, provide a range of potential effects but not a consensus on the likely domestic
economic effects of withdrawal from the PA.
For example, some researchers assumed that when a U.S. PA withdrawal occurred, there would
be in place a U.S. climate policy of either a tax on carbon emissions or a national emissions
trading scheme (ETS) in which GHG emissions were capped.110 In these scenarios, these policy
options were used to meet the emissions goals of the U.S. NDC and resulted in an increase in the
cost of fossil energy. However, the United States has not enacted a carbon tax or trading scheme;
therefore, the applicability of these studies under current policy conditions is unclear. Also, these
studies were published before the enactment of legislation that included a number of climaterelated provisions, including the IRA, the Infrastructure Investment and Jobs Act (IIJA; P.L. 11758), and the CHIPS and Science Act (P.L. 117-167). The climate change mitigation provisions in
these acts were primarily financial incentives to encourage the adoption of low-emissions energy
sources and increases in energy efficiency. The IRA included a number of policies that provide an
incentive to reduce GHG emissions. In addition, the IRA directed EPA to impose and collect a
methane fee, levied on specific methane emissions from facilities in the oil and gas sector.111
Some have criticized the economic modeling approaches of many previous studies because these
approaches do not include the potential for net negative climate impacts resulting from a
withdrawal.112 These could include the economic effects from extreme heat events, droughts,
flooding, and agricultural losses, among others, and how they would change with U.S.
participation or withdrawal from the PA.113 The specific impacts of climate change associated
with U.S. participation in or withdrawal from the PA, if any, are uncertain; another complication
is the timing of those impacts, whether in the near term or at some future time. Some researchers
have considered these types of climate impacts. Some of this research has indicated that
withdrawing from the PA would likely negatively affect the U.S. economy because of enhanced
negative climate effects due both to increased U.S. emissions and potential emissions increases
from other countries.114 In this scenario, a U.S. withdrawal from the PA would result in increased
U.S. GHG emissions, reduced climate mitigation ambition for other countries, and increased
emissions on their part. Other researchers found that withdrawal from implementing the NDCs of
large emitters, such as the United States or China, “would impose considerable costs for all
countries, including those that withdraw.”115 Another researcher using a cost-benefit analysis
found that the costs associated with potential negative climate impacts due to a PA withdrawal
outweigh the benefits, such as increased employment in fossil fuel industries (e.g., coal).116
110 For background on carbon tax and trading schemes, see CRS In Focus IF11103, A Brief Comparison of Two Climate
Change Mitigation Approaches: Cap-and-Trade and Carbon Tax (or Fee), by Jonathan L. Ramseur.
111 P.L. 117-169, §60113.
112 Personal communication with Dr. Irving Mintzer, Senior Research Scholar, Robert H. Smith School of Business,
University of Maryland, 2025.
113 USGCRP, Fifth National Climate Assessment, “Table 1.2 Climate Change Is Already Affecting All US Regions and
Will Continue to Have Impacts in the Near Term: Example Impacts,” https://nca2023.globalchange.gov/chapter/1#
table-1-2.
114 Alex Bowen et al. “The Economic Case for the United States to Remain in the Paris Agreement on Climate
Change,” Policy Brief, Grantham Research Institute on Climate Change and the Environment, London School of
Economics and Political Science, 2020.
115 Francisco Estrada and W. J. Wouter Botzen, “Economic Impacts and Risks of Climate Change Under Failure and
Success of the Paris Agreement,” Annals of the New York Academy of Sciences, vol. 1504, no. 1 (2021), p. 95. The
metric for cost in this study is the median total discounted economic costs of climate change over this century,
expressed as a percentage of a region’s current GDP.
116 Carolina Arlota, “Does the United States’ Withdrawal from the Paris Agreement Pass the Cost-Benefit Analysis
Test?” University of Pennsylvania Journal of International Law, vol. 41, no. 4 (2020), p. 881.
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Just as researchers attempted to assess the economic effects of a potential first U.S. withdrawal
from the PA, researchers also may assess the economic implications of a second withdrawal.
These studies may better reflect U.S. climate policies at the time of the second withdrawal, while
also accounting or controlling for other potential U.S. policy changes.
Potential Effects on International Climate
Cooperation
This section examines some of the concerns that have been raised about the effect of the U.S.
withdrawal from the PA on international efforts to address global climate change. Some observers
have expressed concern that other countries may follow the United States in withdrawing from
the PA.117 Other observers have stated that the U.S. withdrawal may make it difficult to maintain
the level of global ambition necessary to continue to reduce GHG emissions.118 Still other
observers have said that U.S. withdrawal is unlikely to affect emissions reduction commitments
by other countries. Some researchers support the point of view that a U.S. withdrawal from the
PA is unlikely to result in reduced climate mitigation ambition by other parties to the PA, in part
because the mechanism for ambition setting—the NDCs—is based not on reciprocity between
parties, but on action that parties independently determine is consistent with their national
interest.119
To examine these concerns regarding international climate cooperation, this section reviews other
countries’ actions since the initial 2017 announcement of U.S. withdrawal with respect to their
participation in the PA and their ambition with respect to addressing global climate change.
No other country withdrew from the PA after the U.S. withdrawal on November 4, 2020, and no
other country has withdrawn after the most recent (January 20, 2025) U.S. announcement of the
decision to withdraw (as of April 11, 2025).120
Assessing the level of global ambition regarding climate change mitigation is complex, and there
is no generally agreed-upon methodology for doing so. One approach is to assess NDCs, the
vehicle through which Parties to the PA communicate the level of ambition of their intended
contributions to achieving the agreement’s collective goals.121 The UNFCCC prepares an annually
updated synthesis report on NDCs that includes an assessment of the ambition of the NDCs
toward achieving the PA’s goals.122 A synthesis report prepared by the UNFCCC in 2022, after the
United States had withdrawn and then rejoined the PA, found that the ambitions of the majority of
117 Rob Bailey and Gitika Bhardwaj, “What Trump’s Withdrawal from Paris Means for Global Climate Action,”
Chatham House, June 2, 2017, https://www.chathamhouse.org/archive/what-trumps-withdrawal-paris-means-globalclimate-action. See also Urpelainen and Van de Graaf, “United States Non-Cooperation and the Paris Agreement.”
118 Matti Goldberg and Dave McGlinchey, “Five Things to Know About the U.S. Withdrawal from the Paris
Agreement: What President Trump’s Executive Order Does—and Does Not—Mean for Federal and International
Climate Action,” Woodwell Climate Research Center, January 30, 2025, https://www.woodwellclimate.org/uswithdrawal-paris-agreement/. See also Urpelainen and Van de Graaf, “United States Non-Cooperation and the Paris
Agreement.”
119 Urpelainen and Van de Graaf, “United States Non-Cooperation and the Paris Agreement.”
120 United Nations Treaty Collection Depositary, Chapter XXVII: Environment, 7.d, “Paris Agreement,”
https://treaties.un.org/pages/ViewDetails.aspx?src=TREATY&mtdsg_no=XXVII-7-d&chapter=27&clang=_en#7
121 Lauri Peterson et al., “What Determines Climate Ambition? Analysing NDC Enhancement with a Mixed-Method
Design,” Npj Climate Action, vol. 2, no. 1 (2023), p. 1.
122 UNFCCC, Nationally Determined Contributions Under the Paris Agreement: Synthesis Report by the Secretariat,
October 28, 2024, p. 4, Executive Summary I.1, https://unfccc.int/documents/641792 (hereinafter UNFCCC, Synthesis
Report, 2024).
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the Parties continued to increase, as reflected in their individual NDCs.123 At the time of the
synthesis report, the United States was a Party to the PA. The synthesis report stated that “most of
the Parties (74 percent) that submitted new or updated NDCs have strengthened their
commitment to reducing or limiting GHG emissions by 2025 and/or 2030, demonstrating
increased ambition in addressing climate change.”124
A synthesis report issued by the UNFCCC in November 2024 (prior to E.O. 14162) aggregated
all of the NDCs and examined their combined effect on reducing emissions, as an indicator of
NDC ambition to meeting the PA’s climate goals. Its examination of the aggregate levels of
ambition in the NDCs, rather than the levels of ambition stated in the NDCs for individual
countries, found a “stagnation” in aggregate ambition level.125 Specifically, the report stated that
the slight increase in NDC ambition levels reflected “a stagnation in aggregate NDC ambition
level.”126 Countries have continued to submit their NDCs after the U.S. decision to withdraw was
announced in E.O. 14162 on January 20, 2025. As of April 8, 2025, the UNFCCC registry listed
17 countries that had submitted NDCs after the E.O. 14162 announcement.127
Congressional Interest and Options
Since the issuance of E.O. 14162, Members of Congress have shown interest in the U.S. decision
to withdraw from the PA. Some Members have expressed disapproval of the decision, while other
Members have expressed approval.128 Congress may consider legislative options with respect to
the PA, including support for programs that promote the PA’s goals in absence of U.S.
participation, such as economy-wide GHG emissions reductions. Alternatively, some Members
may support legislation that repeals or amends existing programs that support GHG emissions
reductions. Furthermore, as there is currently no consensus among experts as to the withdrawal’s
likely effects on the Earth’s climate system, on the U.S. economy, or on global cooperation to
address climate change, Congress may consider directing research by federal agencies or the
National Academy of Sciences to investigate these questions before taking legislative action.
123 UNFCCC, Nationally Determined Contributions Under the Paris Agreement: Synthesis Report by the Secretariat,
October 26, 2022, p. 4, https://unfccc.int/documents/619180 (hereinafter UNFCCC, Synthesis Report, 2022); Center for
Climate and Energy Solutions, “Q&A: Understanding Paris Agreement NDCs,” at https://www.c2es.org/content/q-anda-understanding-paris-agreement-ndcs/. UNFCCC, Synthesis Report, 2022, reviewed 166 NDCs, including 142 new or
updated NDCs communicated by 195 Parties that were available in the NDC registry as of September 23, 2022.
124 UNFCCC, Synthesis Report, 2022, Executive Summary, paragraph 4 (e).
125 UNFCCC, Synthesis Report, 2024.
126 UNFCCC, Synthesis Report, 2024, Section IV B, paragraph 59, p. 14, states the following:
In comparison, the total GHG emission levels resulting from implementation of the NDCs
presented in the previous version of this report were estimated to be around 53.2 (51.6– 54.8) Gt
CO2 eq in 2025 and 51.6 (48.3–54.8) Gt CO2 eq in 2030. The levels presented in this report, which
reflect a stagnation in aggregate NDC ambition level and updated emission data, are therefore only
0.2 Gt CO2 eq (or 0.5 per cent) lower for 2025 and 0.1 Gt CO2 eq (or 0.1 per cent) lower for 2030
than the estimated emission levels indicated previously.
127 UNFCCC, “Nationally Determined Contributions Registry,” https://unfccc.int/NDCREG.
128 Some Members have introduced resolutions opposing withdrawal from the PA; see H.Res. 68 and S.Res. 36. Some
Members have expressed support for withdrawal from the PA; see Rep. LaMalfa, remarks in the House, Congressional
Record, vol. 171, no. 14 (March 4, 2025), p. H954, https://www.congress.gov/congressional-record/volume-171/issue41/house-section/article/H954-2. See also Sen. Barrasso, remarks in the Senate, Congressional Record, vol. 171, no. 41
(March 4, 2025), p. S1468, https://www.congress.gov/congressional-record/volume-171/issue-41/senate-section/article/
S1468-1.
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U.S. Withdrawal from the Paris Agreement: Process and Potential Effects
Some Members have expressed disapproval of the announcement that the United States would
withdraw from the PA. On January 24, 2025, Representative Bradley Schneider sponsored H.Res.
68, “Expressing strong disapproval of the President’s announcement to withdraw the United
States from the Paris Agreement,” with 161 cosponsors. On the same day, Senator Edward
Markey sponsored S.Res. 36, “A resolution expressing the sense of the Senate that the United
States, States, cities, Tribal nations, businesses, institutions of higher education, and other
institutions in the United States should work toward achieving the goals of the Paris Agreement,”
with 21 cosponsors. Both resolutions, if adopted, would express disapproval of the U.S.
withdrawal from the PA, citing the potential negative impacts on the economy, national security,
and U.S. public health that could result from the withdrawal and the potential benefits in these
areas from participation in the PA.
Other Members have expressed approval of the withdrawal announcement. For example,
speaking in favor of withdrawal from the PA, Representative Douglas LaMalfa cited the need to
“unleash America’s full energy potential,” and Senator John Barrasso cited withdrawal from the
PA as an early accomplishment of President Trump.129
The most recent U.S. NDC of 2024 included commitments to take domestic actions to further the
PA’s goals, including the temperature goals and the emissions reduction goals, such as economywide emissions reductions.130 Whether the United States continues to take these actions is not
contingent on the United States continuing to participate in the PA. Legislation passed in the 117th
Congress, particularly the IRA (P.L. 117-169), included a number of climate-related provisions
that supported these goals and had been projected to reduce U.S. GHG emissions over the next
decade. Examples of such provisions include production tax credits for electricity produced from
low-GHG-emitting renewable energy sources and for domestic production of qualifying solar and
wind components.131 Some researchers estimated that full implementation of the IRA could have
resulted in economy-wide emissions reductions of 43%-48% below 2005 emissions levels by
2035.132 Even with full implementation of the IRA, based on analyses in several studies, these
reductions are unlikely to meet U.S. NDC goals.133 Some Members may choose to provide
continued support for these programs or adjust them to encourage further emissions reductions.
129 Rep. LaMalfa, remarks in the House, Congressional Record, vol. 171, no. 14 (March 4, 2025), p. H954,
https://www.congress.gov/congressional-record/volume-171/issue-41/house-section/article/H954-2. See also Sen.
Barrasso, remarks in the Senate, Congressional Record, vol. 171, no. 41 (March 4, 2025), p. S1468,
https://www.congress.gov/congressional-record/volume-171/issue-41/senate-section/article/S1468-1.
130 UNFCCC, Paris Agreement, Article 2.1a and Article 4.1, 4.4. See also UNFCCC, “The United States of America:
Nationally Determined Contribution,” https://unfccc.int/sites/default/files/2024-12/
United%20States%202035%20NDC.pdf. The U.S. NDC states that with respect to the temperature goals of the PA,
The United States’ NDC is consistent with the Paris Agreement temperature goal of holding the
increase in the global average temperature to well below 2 degrees Celsius above pre-industrial
levels and pursuing efforts to limit the temperature increase to 1.5 degrees Celsius above preindustrial levels.
Further, the U.S. NDC states the following general target: “Economy-wide target of reducing net greenhouse
gas emissions by 50-52 percent below 2005 levels in 2030.”
131 P.L. 117-169, §13101, “Extension and Modification of Credit for Electricity Produced from Certain Renewable
Resources”; §13502, “Advanced Manufacturing Production Credit.” See also CRS Report R47262, Inflation Reduction
Act of 2022 (IRA): Provisions Related to Climate Change, coordinated by Jonathan L. Ramseur.
132 John Bistline et al., “Emissions and Energy Impacts of the Inflation Reduction Act,” Science, vol. 380, no. 6652
(2023), p. 1324.
133 CRS Report R47385, U.S. Greenhouse Gas Emissions Trends and Projections from the Inflation Reduction Act, by
Jonathan L. Ramseur.
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U.S. Withdrawal from the Paris Agreement: Process and Potential Effects
By contrast, in the 118th and 119th Congresses, a number of Members have called for the repeal of
some or all of these climate-related provisions, as well as other emissions reduction legislation.
For example, H.R. 2811, introduced in the 118th Congress, included the repeal of the Greenhouse
Gas Reduction Fund, created under the IRA, that provides financial and technical assistance to
carry out activities to reduce GHG emissions. In an example from the 119th Congress, in February
2025, both the House and the Senate passed a joint resolution (H.J.Res. 35) disapproving of EPA’s
“Waste Emissions Charge” (WEC) rule imposing a fee on methane emissions. President Trump
signed the measure on March 14, 2025, enacting the resolution (P.L. 119-2). It is uncertain what
effect the enacted joint resolution will have on the implementation of the WEC, which is required
by statute (IRA; P.L. 117-169, §60113). Considering the announcement to withdraw from the PA,
some Members in the 119th Congress may pursue efforts to repeal or amend existing programs
that support U.S. NDC commitments; there also may be Members who pursue efforts to codify or
continue funding existing programs that support reducing U.S. GHG emissions.
Given the uncertainty of the withdrawal’s effects on climate change mitigation, the U.S. economy,
and international climate cooperation, Congress may seek to obtain additional information on
these and other potential effects before considering legislative action. Congress may consider
directing the National Academies of Sciences, Engineering, and Medicine, or federal programs
and agencies, to study these effects and to report to Congress.
Author Information
Jonathan D. Haskett
Analyst in Environmental Policy
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