What the First Conference on Transitioning Away from Fossil Fuels Means for the Duty to Co-operate

[Joanna Wils is a PhD researcher at the Institute for International law of KU Leuven, specialising in international environmental law. She holds an LL.M. in Environmental & Energy Law from NYU School of Law and currently serves as a Belgian UN Climate Youth Delegate]

“The COP of truth cannot support an outcome that ignores science”, were the words of the Colombian delegation at the end of COP30 last fall. The thirtieth Conference of the Parties (‘COP’) to the 1992 UN Framework Convention on Climate Change (UNFCCC) was held in Belém, Brazil, and had been announced as ‘the COP of truth’.

Disappointed that the final text of the negotiations did not mention fossil fuels, Colombia announced the First Conference on Transitioning Away from Fossil Fuels in Santa Marta, Colombia, co-organised with the Netherlands. Both countries argued that it was important to keep the ‘momentum’ on the transition going. To do so, they sought a forum outside the global context of the UNFCCC.

While this reach outside the global climate framework could be interpreted as a breach of the duty to co-operate, this blogpost argues that it is precisely justified under that duty and that it might mark the progressive development towards a more substantive understanding of co-operation. To do so, it starts by establishing the inability of the UNFCCC processes to confront the root cause of climate change – fossil fuels. Then, it goes on to describe the customary duty to co-operate in good faith for the protection of the environment, a duty with a procedural and a substantive component. While it is difficult to demonstrate a breach of the good faith requirement, the substantive component of the duty is not being met. Given that the Santa Marta conference stems from a concern to reach substantive, collaborative progress, this post concludes that it is justified under the duty to co-operate. In addition, it could mark the beginning of a progressive development towards a more substantive implementation of the duty.

Fossil Fuel Momentum

The momentum for a transition away from fossil fuels arguably started at COP28 in Dubai, United Arab Emirates when the cover decision called on State parties to contribute to the “[t]ransitioning away from fossil fuels in energy systems (para. 28(d))”. Despite the lack of a global roadmap, the simple mention of a fossil fuel phaseout was welcomed as an important step. And yet, at COP29 fossil fuels did not make it into the final text.

A couple of months before COP30, the International Court of Justice (ICJ) delivered its Climate Change Advisory Opinion. In the Opinion, the Court had made clear that involvement in different aspects of the lifecycle of fossil fuels can constitute a violation of international law. The Court covered:

“fossil fuel production, fossil fuel consumption, the granting of fossil fuel exploration licences or the provision of fossil fuel subsidies(para. 427)”.

Despite that ruling, and despite a coalition of around 80 States that asked to address a fossil fuel phaseout, the final text of COP30 did not reflect that ambition. And so, the scientifically recognised main cause of the problem that the UNFCCC aims to resolve (IPCC AR6 Figure 2.1a) did not make it into the two most recent cover decisions. This is especially alarming considering that the ICJ (para. 437) and the UN Special Rapporteur on Human rights and Climate Change have not shied away from putting the finger on the wound.

The Duty to Co-operate

Since the adoption of the UN Charter, the international order is built on a logic of co-operation. While that does not imply a generally applicable obligation for States to co-operate in all of their endeavours, such an obligation is recognised in international environmental law (see principle 24 of the 1972 Stockholm Declaration, principles 7 and 27 of the 1992 Rio Declaration, para. 82 of the 2001 Mox Plant case by the ITLOS in the maritime context, para. 77 of the 2010 Pulp Mills case by the ICJ, paras 140-142 of the 2025 Climate Change Advisory Opinion by the ICJ). That duty is not only procedural, but also substantive in nature: it is “intrinsically linked to the duty to prevent significant harm to the environment” (para. 141 of the 2025 Climate Change Advisory Opinion by the ICJ).

For environmental framework conventions, the duty to co-operate carries a larger weight. While these conventions allow the law to develop at the speed of scientific research and political understanding, they are extremely dependent on good faith co-operation of the State parties. The duty to co-operate constitutes the “driving force for the progressive development” of the intended legal regime.

For the UNFCCC specifically, international co-operation is needed to concretise the objective to reach a:

“stabilisation of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system(article 2)”.

In the past, co-operation has led to the adoption of the 1997 Kyoto Protocol and the 2015 Paris Agreement.

In “Good Faith”

The duty to co-operate includes a condition of good faith. In the 1974 Nuclear Tests case, the ICJ wrote that:

“[o]ne of the basic principles governing the creation and performance of legal obligations […] is the principle of good faith. Trust and confidence are inherent in international co-operation, in particular in an age when this co-operation in many fields is becoming increasingly essential)”.

(para. 46)

That statement was made in the context of unilateral declarations, but the obligation to act in good faith has been repeatedly established in treaty contexts. Article 26 of the Vienna Convention on the Law of Treaties positions good faith as a component of pacta sunt servanda, which has been linked to the concretisation of general treaty obligations in the Gabc̆íkovo-Nagymaros case of the ICJ (para. 112), something that is particularly relevant to framework conventions. The ICJ has also declared the duty to co-operate in good faith applicable during stages of treaty negotiations in the Pulp Mills case to ensure “that the negotiations are meaningful (paras 145-146)”.

The complexity of UNFCCC climate negotiations, reported by the Earth Negotiations Bulletin, makes it hard to assess good faith. Nevertheless, the failure to address the root cause of climate change reveals that the duty to co-operate to prevent significant harm to the environment is not being fulfilled on a substantive level. It is in this context that the Netherlands and Colombia have taken matters into their own hands.

Santa Marta: Transnational Co-operation on Implementation

The website of the First Conference on Transitioning Away from Fossil Fuels set out what it is not: not a forum to negotiate a fossil fuels treaty, not a replacement of the UNFCCC or the Presidency’s roadmap, nor a space to convince ‘skeptics’. Rather, as the preliminary outcome documents make clear, the conference revolved around the accelerated implementation of the objective already established under the UNFCCC framework (article 2).

Fifty-seven States participated in the conference, alongside subnational governments, numerous civil society groups and academics. The process was transnational rather than international, in the sense that it focused on the building of trust and the sharing of knowledge across State boundaries, rather than renegotiating international legal relations. The co-operation that the conference aimed to promote is practical: the tough nuts to crack on the agenda were economic dependence, supply and demand transformation, and international climate co-operation and diplomacy.

Concrete outcomes of the conference are voluntary initiatives focused on inter-state co-ordination. They include the launch of a Science Panel for the Global Energy Transition (SPGET), and the establishment of three workstreams: one on national roadmaps to transition away from fossil fuels, one on macroeconomic dependencies and financial architecture, and one on producer–consumer alignment. The idea is that the SPGET will support States in the design of their roadmaps, which will help them to implement their obligations under the UNFCCC.

The Duty Not to Give up on Co-operation

These initiatives, albeit legally non-binding, could be seen as a violation of the duty to co-operate within the UNFCCC context. Such a claim would, however, rely on a purely procedural argument that co-operation must remain within the bounds of existing institutional structures. From a substantive point of view, the conveners of the First Conference on Transitioning Away from Fossil Fuels aim to bring the objective of the UNFCCC closer. To do this, they are testing options outside of the established framework. Crucially, there is no intention to replace the UNFCCC procedures, but rather an aspiration to move beyond blockades and create opportunities for progress. By focusing on implementation and tying the outcomes back to the UNFCCC, the conference prevents undue fragmentation.

Therefore, this blogpost argues that the Conference is justified under the duty to co-operate to prevent significant harm to the environment. Even more so, it might mark a progressive development towards a more fundamental understanding of the duty to co-operate that assigns more weight to the substantive aspect of environmental harm prevention. With a substantive focus, the duty could require of States that they attempt to create new pathways to effectively prevent significant harm when established co-operative procedures do not deliver.

While it is too early to establish a deepened customary obligation – since customary law requires general practice accepted as opinio juris (ILC, conclusion 2 of the Draft conclusions on identification of customary international law)  – this ostentatiously announced reach outside the UNFCCC framework can be a significant turning point, even when there is no lawmaking intention. As Hans Kelsen put it last century, custom is “unconscious and unintentional lawmaking (Principles of International Law, p. 308)”.

The Santa Marta conference may start a more general practice of substance-driven initiatives. In that regard, a second conference has already been announced. For the formation of opinio juris, the outcome document is relevant, as it includes the statement that:

“[p]articipants discussed that advancing a just, orderly, and equitable transition away from fossil fuels requires stronger international co-operation and more effective governance arrangements. They emphasised that existing multilateral frameworks remain essential for legitimacy and common direction, but that many of the practical conditions needed for implementation require more coordinated, targeted, and operational forms of collective action”.

(p. 12)

While this does not amount to an expression of opinio juris, it comes from a place of perceived necessity.

Similar initiatives and a growing opinio juris could elevate a foundational duty not to give up on co-operation to a customary status. Once States reasonably establish that existing co-operative structures will not succeed in bringing the envisioned environmental protection closer, the duty would require that new procedures are sought to restructure the co-operation mechanisms, gearing the procedural aspects towards the substantive ones. To the extent possible, those procedures would have to tie back to the existing institutions to avoid fragmentation, as happens here with the UNFCCC.

Common but Differentiated Responsibilities and Respective Capabilities

Now, minilateral co-operation raises concerns about the application of Common but Differentiated Responsibilities and Respective Capabilities (CBDR-RC), which accords responsibilities differentially between States across the globe in pursuit of the shared goal of climate protection. Minilateral initiatives risk excluding developing States from negotiations, while prioritising only the concerns of participating States, which can disrupt the delicately balanced distribution of international rights and responsibilities.

Nevertheless, regrouping with a select number of countries might be exactly what is necessary to propel climate co-operation at the global level. Not only can the transnational focus foster multilateral trust, the smaller number of participating States also reduces State opportunities to hide behind the shortcomings of other States. The announcement that Tuvalu and Ireland — once again a pair from the Global North and Global South — will co-host the next conference, demonstrates some sensitivity to CBDR-RC. Still, CBDR-RC must remain a central concern in searches for different co-operative climate mechanisms.

To make the link with the global level, where CBDR is central to climate law, the Santa Marta conference report will be handed over to the previous Brazilian and the upcoming Turkish-Australian COP presidencies. The pivotal question is whether that handover will effectively enhance global co-operation at COP31 in Antalya, Türkiye, or whether it will deepen global divisions. The reality on the negotiation grounds in Antalya will have to show whether minilateral regrouping can rebuild trust and support the duty to co-operate at the global level.

Outlook

The First Conference on Transitioning Away from Fossil Fuels arose from dissatisfaction with international co-operation in the UNFCCC context. Considering that the co-operative structures of the UNFCCC currently fail to support progress on the topic of fossil fuels, this blogpost argues that the Santa Marta conference was justified under the duty to co-operate.

More so, it posits that the conference holds the potential to deepen the meaning of the duty towards a more substantive understanding that requires States not to give up on co-operation when existing procedures fail to prevent environmental harm. Such a duty not to give up on co-operation might require creativity and courage, as it is not guaranteed that the first new initiative will suffice. It also demands continued attention to principles such as CBDR-RC and good faith.

The ongoing negotiations on a global treaty on plastic pollution might be the next opportunity for States to re-think international co-operation as there, too, progress is taking a very long time to materialise.

Photo attribution: by Travis Leery on Unsplash