Did the ICJ advisory opinion shift the dial at COP30?
Less than five months have passed since the International Court of Justice (ICJ) produced its landmark advisory opinion (AO) on climate change. The document has already been woven into the narrative of new climate litigation and wedged into existing legal cases, and judges are starting to reference it in their rulings.
Hopes have also been high that it could be a diplomatic lever during international climate negotiations. But in reality, during the hectic and tense atmosphere of talks in the Brazilian city of Belém, it was a difficult tool to wield.
Monaco, Mexico, the Alliance of Small Island States (AOSIS) and the group of Least Developed Countries (LDCs) called for acknowledgement of the ICJ’s conclusions (as well as the other two climate advisory opinions from the Inter-American Court of Human Rights and the International Tribunal on the Law of the Sea) during various presidency consultations. Speaking at a press conference during COP30, Earth Negotiations Bulletin team leader Jennifer Bansard said these requests were “at very generic levels” and did not go into the courts’ specific actionable findings.
Red, red line
The closest the ICJ AO came to being referenced in a formal text was during a review of the Warsaw International Mechanism for Loss and Damage (WIM). This is important because experts believe it has particularly significant implications for the loss and damage fund.
During these discussions, the Independent Alliance of Latin American and the Caribbean Nations (AILAC) said the AO provides “an informed legal foundation” for advancing work on loss and damage, “including the need for comprehensive assessment and health protection from vulnerable groups and integral forms of reparation.” This was supported by Vanuatu, which led the diplomatic work that resulted in the ICJ opinion.
But Saudi Arabia, representing the Arab Group, responded that the court’s final outcome is “non-binding” and “does not represent parties’ views” even though it recognises that it participated in the process that led to it. Negotiations are a “party-driven process based on consensus, and not litigation”, it said.
A source in the room said the group described the inclusion of the ICJ AO anywhere in the document as a “deep, deep, deep red line”. “If you insist on discussing it, we might as well just suspend this session to not waste each other’s time,” said Saudi Arabia’s negotiator. The AO is not mentioned in the final agreed WIM text.
Singh says the group was particularly concerned about the ICJ's reference to the status of a state as developed or developing as “not static". “They feared that formally recognising the opinion would open the door to limitless legal liability for fossil fuel production.”
Just transition
The AO’s recognition of a “just and fast transition in line with best available science” was mentioned by Fiji, for the Alliance of Small Island States (AOSIS), at an inaugural meeting over the Just Transition Work Programme. AILAC, Egypt and the UK also raised it during just transition negotiations, while Malawi used it to try to frame transition finance as a legal necessity.
Some states had expected the cover text to recognise the AO in some form but this was quietly withdrawn by the Brazilian COP presidency.
It is notable how few states raised the document in formal settings, and barely any of those were big emitters. The EU, for example, apparently supported language on the AO, but did not actively push for it.
This is despite the fact that the UN asked the ICJ for the advisory opinion unanimously, that its final document reflected the general sentiments of the vast majority of states and that most countries have accepted the court’s jurisdiction (see the excellent visualisation below developed by law professor Margaret Young and designers Dan Parker and Stanislav Roudavski).
Harjeet Singh, founding director of the Satat Sampada Climate Foundation and strategic advisor to the Fossil Fuel Non-Proliferation Treaty Initiative, believes all governments understand the ICJ’s conclusions “perfectly”. “That is precisely why the battle lines were drawn so sharply. Vulnerable countries advocated for it because it validates their claims for justice, while historical and large polluters pushed back strongly to avoid acknowledging any legal framework that implies liability.”
However, he recognises that developed countries “neither championed nor explicitly opposed it in open plenary to avoid negative optics”, instead “quietly navigating around its implications for liability”.
The ICJ’s recognition that COP decisions may have legal effects could be making negotiators more wary of what they agree to.
In the closing plenary, Palau for AOSIS noted the ICJ’s clear assertion of 1.5°C as the legal temperature limit. Yet the final Mutirao decision explicitly reiterates the Paris Agreement’s language of “pursuing efforts” to reach that level, while retaining the original goal of “well below 2°C”.
The reluctance of some parties to only mention the 1.5°C goal in decisions “is likely informed by the way the ICJ has gone about using past decisions as interpretive tools”, says Bansard.
Bansard believes the final decision is “actually quite elegant” in stressing the dangers of going beyond 1.5°C. But Harj Narulla, a barrister specialising in climate litigation and counsel for Solomon Islands, thinks it has “actually undermined” the ICJ’s conclusions.
Capacity and coordination
Barring a few nations like Saudi Arabia, however, Narulla sees the overall outcome as a “failure of capacity and coordination, rather than a principled opposition to using the AO”.
Insiders said state negotiating teams are still too separate from their legal teams, and the former were not properly briefed on how the AO could be used in practice.
The leadership that had been expected from climate-vulnerable countries, particularly the island nations that had advocated for the AO in the first place, also seems to have been absent. A briefing by Ed King and Lindsey Smith, who work on international climate strategy for the Global Strategic Communications Council, describes AOSIS’s showing at COP30 in particular as “insipid”.
Ralph Regenvanu, minister of climate change of Vanuatu and a key architect of the AO campaign, mentioned it several times in public, including at Cambodia’s announcement that it would formally support a fossil fuel non-proliferation treaty. But his focus seems to be on pursuing a new UN resolution recognising the ICJ’s findings.
Neither AOSIS nor Regenvanu responded to requests for comment.
Narulla says there was no strategic push from the start to weave the AO into the agenda and negotiating tracks, so any references happened in an ad hoc way. As well as not being included in final negotiated texts, he says this meant it could not be used to confront emerging challenges to climate science and the centrality of the 1.5°C goal. “It was on the back foot,” he says.
Singh admits that, due to the tight timeframe between the ICJ decision and COP30, there was not enough time to “fully socialise it as a political tool”. He says climate justice activists need to expand their reach beyond the usual champions - the Pacific and AILAC nations - particularly from the LDCs, “to create a truly global front”.
Undercurrents
Nonetheless, Mohamed Adow, director of Power Shift Africa who has followed the climate talks for many years, believes the AO is “starting to influence the wider narrative around responsibility and liability”.
“Though it did not make the ‘waves’ in the formal text that many hoped for, it was clearly the ‘undercurrent’ beneath many streams of negotiation,” agrees Singh. He says climate activists still intend to use the AO’s “legal clarity” to hold polluters to account and demand reparations, “fundamentally shifting the loss and damage conversation from one of discretionary charity to one of binding legal obligation”.
There is one important - and tangible - success story; the community of El Bosque in Tabasco, México, did manage to use AO as leverage in recent negotiations with the Mexican government over its latest nationally determined contribution (NDC) (see below).
Nikki Reisch, climate and energy programme director at the Center for International Environmental Law, an organisation that supports the youth activists who sparked the AO process, is keen to highlight a less-discussed part of the advisory opinion; that states have a legal duty to cooperate, in good faith and in line with common but differentiated responsibilities, to prevent climate harm and protect human rights.
Reisch said this “underscored the need to reform the UNFCCC to make it fit for purpose, prevent fossil fuel industry influence and allow majority voting so that a handful of countries cannot block necessary climate action” - debates that have reached fever pitch over the past year.
See you in Santa Marta
The opinion may actually play a bigger role in 2026. During the last tense plenary, after Colombia criticised the fact that it was not allowed to object to a final deal that had a conspicuous fossil fuel-shaped hole in it, Brazilian COP president André Corrêa do Lago said he would bring forward a fossil fuel roadmap outside the formal COP process and gave a nod to the First International Conference on the Just Transition Away from Fossil Fuels.
A press release from the Fossil Fuel Treaty initiative promoting the new conference, which takes place next April in the port city of Santa Marta, Colombia, and will be co-hosted by The Netherlands, says it will align with the AO, “which confirmed that states have a legal obligation to protect the climate, including by addressing fossil fuel production, licensing and subsidies”.
The Belém Declaration on the Just Transition Away from Fossil Fuels, signed by 24 countries from Australia to Vanuatu which Singh describes as the “foundational text” for the new coalition, does explicitly “welcome” the AO in its third paragraph.
In the continuing absence of any system within the UNFCCC to test whether individual NDCs are sufficient and represent a fair share of the collective temperature limit, experts also expect more domestic lawsuits underpinned by the advisory opinion, and say inter-state litigation cannot be ruled out.
“COP30 in Belém is by no means the last word on the ICJ AO or the climate duties it confirms,” says Reisch.
