For the second time since the Paris Agreement on climate change was adopted, the US this week formally withdrew from the global pact following a 12-month mandatory period since President Donald Trump announced he would pull his country out on his first day in office in January 2025.
Since then, the US has axed most of its international climate funding and this month said it would exit the UN climate convention (UNFCCC) – which underpins the UN climate process and the Paris Agreement – the Intergovernmental Panel on Climate Change (IPCC), which is the world’s most authoritative climate science body, and the Green Climate Fund (GCF), the world’s biggest multilateral climate fund.
Trump to pull US out of UN climate convention and climate science body
As the Trump administration turns its back on the UN climate regime, UN climate chief Simon Stiell described the move as a “colossal own goal”, while the GCF – to which the US has failed to deliver billions of dollars in promised support – said the country would lose its board seat but operations would continue.
Climate diplomacy experts say some of the changes announced by the US president could remain symbolic or be reversed in the future, while warning that the reputation of the world’s second-biggest emitting country could suffer a big hit in the long term.
Other countries may follow US Paris exit
Marta Schaaf, Amnesty International’s climate programme director, said the US’s second exit from the Paris Agreement on January 27 (the first was during Trump’s first term) “sets a disturbing precedent” that could instigate a “race to the bottom”, encouraging other countries to leave.
“The US is one of several powerful anti-climate actors but as an influential superpower, this decision, along with acts of coercion and bullying of other countries and powerful actors to double down on fossil fuels, causes particular harm and threatens to reverse more than a decade of global climate progress under the agreement,” she said in a statement.
So far no other signatories have publicly announced they will quit the 2015 climate agreement, but Israeli media recently reported that the country is discussing a withdrawal under pressure from the US. Last year, Argentina also hinted at a possible exit but did not follow through.
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COP30 President André Aranha Corrêa do Lago said himself that in the months leading up to last year’s UN climate conference in Brazil, there was “a lot of noise about possible additional exits”, after the world’s largest economy said it would withdraw.
The Trump administration has been called out in other UN processes, after being accused of employing “bullying” tactics at the International Maritime Organization (IMO) to persuade smaller countries to vote against the entry into force of a green shipping deal. This pressure resulted in a delayed decision.
Allie Rosenbluth, Oil Change International’s US campaign manager, said the US withdrawal from the Paris Agreement “is a betrayal of the communities at risk from climate disaster, especially those on the frontlines of the crisis in the Global South”.
Legal uncertainties around UNFCCC withdrawal
This January, in an unprecedented move, the White House also announced the US would leave the broader UN Framework Convention on Climate Change (UNFCCC). This would take effect one year after formally notifying the UN, which it had yet to do as of the time of publication.
The UNFCCC could be harder to rejoin than the Paris Agreement – which was last done through an executive order issued by former President Joe Biden – because the US Senate first gave unamimous “advice and consent” for ratification of the UNFCCC in 1992, making the legal situation more complex.
Some experts believe the US would need Senate authorisation to formally withdraw from the UNFCCC, and there are questions around whether the move would be legal at all.
Trump’s presidential memorandum says that “for United Nations entities, withdrawal means ceasing participation in or funding to those entities to the extent permitted by law”. To all intents and purposes, the US had already disengaged from the UN climate process during Trump’s first year in office, cutting funding for the UN’s climate body and not sending a delegation to COP30.
However, if the US does not formally notify the UN of its withdrawal from the UNFCCC, that could potentially ease legal concerns for the Trump administration, according to Michael Gerrard, climate change law professor at Columbia Law School.
Could the US rejoin the UNFCCC?
Gerrard told Climate Home News that if the Trump administration does not officially withdraw from the UNFCCC, “then I don’t see a legal obstacle to a subsequent administration resuming funding and participation”. “Even if the US does formally withdraw now, a new president might well be able to rely on the prior consent in rejoining; that issue has never been decided by the Supreme Court,” he added.
Sue Biniaz, the US State Department’s Principal Deputy Special Envoy for Climate until January 2025, and Jean Galbraith, professor at the University of Pennsylvania Carey Law School, wrote on the Just Security blog that the mainstream legal view is that the president may constitutionally withdraw the US 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.
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Under international law, they added, rejoining is straightforward. For the UNFCCC, a state can become a party 90 days after depositing its instrument of ratification or accession, and following that, the US could rejoin the Paris Agreement, which would take 30 days after the deposit of its instrument.
From the perspective of domestic law, the two climate law experts argued that the original Senate resolution remains in effect (unless repealed by the Senate) and provides the legal authority needed for a future president to rejoin the UNFCCC. He or she could also seek a second round of “advice and consent”, ask Congress to approve rejoining, or potentially join the UNFCCC under the president’s independent constitutional powers, they added.
Loss of US leadership and credibility
Irrespective of whether the White House does move to rejoin the UN climate regime at any point, analysts said the Trump administration’s hostile attitude and disengagement has damaged the standing of the US when it comes to global climate action and the energy transition.
Biniaz and Galbraith wrote that the world is used to the US “flip-flopping on climate”, because it refused to ratify the Kyoto Protocol and quit the Paris Agreement once before, but “withdrawal from the entire regime takes US abdication of climate leadership to a new level”.
Though many countries may be relieved that the Trump administration is not participating given its current policies, they said: “in the longer term, US absence could have a negative impact on the effectiveness of the regime and the willingness of other countries to take ambitious action.”
Nikki Reisch, climate and energy director at the Center for International Environmental Law, warned that “it will not be easy for the US to regain credibility or leadership on climate.”
While an “informal withdrawal” from the UNFCCC may “avoid some paperwork” and avoid potential lawsuits, she said it would not “insulate this administration from scrutiny and legal challenge on other grounds, particularly as it continues to unwind climate progress, dismantle environmental protections, and expand production of the fossil fuels”.
Reisch noted that US states and local governments have been making efforts to “fill the void where the federal government has abdicated its duties”. “Other countries, too, should see the Trump administration’s retreat as an invitation to step up, stand together and move forward,” she added.
The post Explainer: Out of Paris, but will the US formally quit the UN climate regime? appeared first on Climate Home News.
Explainer: Out of Paris, but will the US formally quit the UN climate regime?
One of the key expected outcomes from the upcoming COP31 climate summit in Antalya, Turkey, is the launch of a “just transition mechanism”.
This follows years of calls from civil society to support a “just transition” as countries shift towards low-emissions energy systems and away from fossil fuels.
At the COP30 UN climate talks last year in the Brazilian city of Belém parties agreed to establish a “mechanism” to support this goal, called the “Belém-Antalya mechanism” (BAM).
Groups that have championed the BAM want it to act as a central hub on just transitions, providing support for workers and communities around the world.
However, the details of exactly what the much-touted BAM will consist of remain vague, with developed and developing countries disagreeing about its functions and purpose.
Disagreements continued at the UN climate talks in Bonn in June 2026, including on the crucial question of how the BAM will be financed.
Here, Carbon Brief looks at where the idea for the BAM came from, how it could support just transitions and what to expect from COP31.
How has a ‘just transition’ featured in UN climate talks?
A “just transition” is the idea that workers and communities should be supported in the shift to a low-carbon economy. It is a central principle behind the idea of climate justice.
Often, the term refers to those linked to the fossil-fuel industry, but it can also refer to transitions taking place in agriculture, heavy industry and various other sectors.
The concept originated in the 1980s, when US labour unions forged alliances with environmental justice groups. It has since become a key part of international climate discussions.
The preamble to the 2015 Paris Agreement includes a commitment to “tak[e] into account the imperatives of a just transition of the workforce and the creation of decent work and quality jobs in accordance with nationally defined development priorities”.
Bert De Wel, policy officer at the International Trade Union Confederation (ITUC), tells Carbon Brief:
“The labour movement is very happy with the wide audience and broad political support that the concept has received since its inception in the 1980s. The inclusion in the Paris Agreement, with the reference to the creation of decent work and quality jobs was a milestone for the movement. While other demands have been added…we continue to stress the labour dimension as being central to the concept.”
Three years after the creation of the Paris Agreement, at COP24 in the former coal-mining city of Katowice, the Polish presidency highlighted the issue of just transitions.
The need for carbon-cutting policies to ensure “a just transition of the workforce” that creates “decent work and quality jobs” was included in the “Silesia declaration”, issued by the presidency during the first week of COP24.
While the declaration was only signed by 50 countries – roughly a quarter of the parties at the summit – it was still “noted” in the final COP text.
This helped to drive momentum behind the idea, culminating in formal agreement at COP27 in Egypt to launch a “work programme on just transition” (JTWP).
De Wel says the establishment of the JTWP was a “major step forward” that allowed parties to “speak about just transition in more concrete terms”.
In the years since, negotiators have worked to flesh out the JTWP, with disagreements between parties about what its purpose should be.
Broadly, developed countries would like it to focus on domestic workforces, while some nations want a more global outlook, including support for transitions in developing countries.
The JTWP has proved a challenging negotiating space, with talks at the COP29 summit in 2024 closing without an agreement, in what one observer dubbed a “betrayal”.
However, despite these frustrations, parties at COP30 in Brazil agreed to establish a new institutional mechanism on just transitions, which has become widely known as the BAM. The move was hailed as a “victory” by civil society.
Where did the ‘just transition mechanism’ come from?
In the run-up to COP30, civil society began to push for the establishment of an “institutional arrangement” that would move work under the JTWP from talk into action.
(This was originally called the “Belém action mechanism” by civil society groups, who subsequently updated this to the “Belém-Antalya mechanism” following the outcome at COP30. However, in the JTWP text agreed at COP30 it is only described as a “mechanism”, sometimes also referred to as the “just transition mechanism”.)
Anabella Rosemberg, senior advisor on just transition at NGO umbrella group Climate Action Network (CAN) International, tells Carbon Brief:
“The idea of the mechanism emerged from the collaboration of civil society, trade unions, feminist groups, youth and Indigenous peoples in the UNFCCC.
“It was clear that the kind of activities being run under the JTWP – two dialogues a year and one ministerial – would not support the delivery of just-transition strategies on the ground, so a new approach was developed to get words into action.”
Following the inception of the idea, civil society did “tonnes of stuff to boost it up the agenda”, Dr Leon Sealey-Huggins, a senior campaigner at the charity War on Want, tells Carbon Brief.
This ranged from presenting demands and proposals to different constituents, organising joint letters and writing policy papers, all the way through to designing logos, creating memes and even a song.
These efforts ultimately paid off: during the Bonn climate negotiations in June 2025, one draft text included the idea for a new institutional arrangement. One of the options in the draft text was for a “toolbox, guidance framework, global platform, technical assistance network [or] mechanism”.
![Paragraph 28 of the JTWP text published 25 June 2025. The text reads "28. Options for further implementation of the United Arab Emirates just transition work programme Option 1: Improving existing modalities Option 2: New institutional arrangements [toolbox, guidance framework, global platform, technical assistance network, mechanism] Option 3: Defer decision to 2026"](https://www.carbonbrief.org/wp-content/uploads/2026/11/para28-1024x334.png)
This inclusion was broadly welcomed as a “big win” for civil society groups, although parties acknowledged that more needed to be done to flesh out the idea.
Going into COP30, civil society groups continued to push the idea of creating a BAM, with protests, banners and badges visible around the venue.
Early in negotiations, the G77 and China – a large coalition of developing countries at UN climate talks – put forward their own proposal for a just transition “mechanism”. This, they suggested, could provide technical assistance, support international cooperation and help to foster partnerships in an effort to address implementation gaps.
Their proposal faced initial pushback from developed-country parties including Norway, the UK and others, who opposed it due to concerns that it would duplicate existing systems and require additional funding.
Developed countries also opposed the use of the term “mechanism”, with the EU suggesting an “action plan” as a potential alternative. Nevertheless, the creation of a “mechanism” was included in the final draft text on the JTWP.
This text was formally approved during the COP30 closing plenary to extended applause from many in the hall.
In a statement at the time, Chiara Martinelli, director at CAN Europe, welcomed the decision:
“Delivering BAM was a major civil society win. It creates a coordinated institutional home to drive forward progress on the just transition.”
The decision to develop the mechanism included a request for parties to work over the subsequent year – through to COP31 – on a plan to get things started.
What role could the mechanism play in facilitating ‘just transitions’?
According to civil society, the BAM could help tackle the fractured just-transition landscape by centralising resources and helping to overcome a number of barriers.
Speaking to Carbon Brief, Rosemberg says the just-transition space “lacks coordination and the right kind of support and is quite disconnected from climate action imperatives”. She adds:
“The BAM can play a role in bringing those [people] trying to make just transition happen together, identify gaps and barriers, foster cooperation and accelerate support.”
Civil society has put forward a number of proposals likely to inform the structure of the BAM. Most consist of a mechanism with three parts, which would encompass and expand upon the work that is currently being carried out under the JTWP.
One proposal by a coalition of five NGOs suggests the mechanism is formed of a steering body, a “knowledge arm” and an “implementation arm”.
The steering body would coordinate the work of the two arms of the BAM, including deciding the topics that should be discussed under the ongoing JTWP, which will continue to feature in climate negotiations. They suggest the body would recommend topics that require negotiation when “gaps that require political guidance are identified”.
Their proposal is illustrated in the infographic below, showing the steering body acting as a central hub for work within the BAM.
The final part of the BAM, the “implementation arm”, would act as a hub to enable and coordinate technical, financial and knowledge-based assistance for those pursuing a just transition.
Rosemberg says the vision of civil society is for work to go “beyond negotiators’ dialogues”. She says the BAM could enable the organisation of a “matchmaking platform” to provide support faster, as well as dedicated groups to identify and mobilise financial resources. She adds:
“Finally, through bottom-up identification of barriers, the BAM can also allow a discussion on enabling just transition that is informed by practitioners. The BAM can show that implementation does not necessarily mean taking issues outside of the UNFCCC.”
A separate proposal for the structure of the BAM from the Global Campaign to Demand Climate Justice (DCJ) – a separate coalition of NGOs – similarly proposes three elements. These would be: coordination and coherence; knowledge generation; and international cooperation and support.
Sealey-Huggins, who is affiliated with DCJ, notes:
“If it works in practice, what we’ll see is a cascade of just-transition policies implemented across countries, across sectors in a unifying, transformational moment for justice-centered climate action, and that will be the key to unlocking the transition that’s been missing so far.”
Another proposal for the BAM comes from the Grantham Institute at the London School of Economics. It suggests the three functions of the mechanism should be capacity-building, technical assistance and knowledge-sharing, but it recommends a dual-arm structure comprising a policy arm and an operational arm.
De Wel tells Carbon Brief that while there is “rather broad consensus on the functions”, parties are pushing in “very different directions” on how the BAM will be set up.
What are the financial implications of the mechanism?
Within UN climate negotiations, some parties have raised concerns about the potential cost of the mechanism.
The push to launch the BAM comes at a time when the UNFCCC itself is facing a funding gap, following the US withdrawal. Several other parties have also delayed or reduced their contributions, in response to changes in domestic priorities.
This has led to the UNFCCC cancelling events and not filling vacated positions, as the organisation struggles to carry out its existing functions.
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As such, some parties have expressed hesitancy about creating another mechanism under the remit of the UNFCCC, which als