9 March 2026

Introduction

At its core, engagement on climate mobility is an effort to put people at the heart of climate action. The International Court of Justice (ICJ), through its 2025 Advisory Opinion on the Obligations of States in respect of Climate Change, took a massive step toward centering people in climate action. The Advisory Opinion is peppered with references to the profound and unevenly distributed impacts of climate change – and, in particular, how humans can live safely and with dignity.

This article examines elements of the Advisory Opinion that impact climate mobility and reflects on how they advance the goals of the Nansen Initiative Protection Agenda. It also identifies several examples where the Court’s views have already been leveraged in legal and policy circles for action on climate mobility, and it provides recommendations for further strategic engagement. While the Advisory Opinion itself is remarkable, its ultimate impact will depend on the advocates and policymakers who invoke it to increase support for climate-impacted communities, whether to adapt in place or to move safely and humanely.

The road to the ICJ

By 2015, it had become clear to most States that deeper legal and policy engagement with the impacts of climate change was non-negotiable. Just weeks before the Paris Agreement was signed, 109 countries endorsed the Nansen Initiative Protection Agenda, which was the culmination of a three-year process. While the Nansen Initiative’s original focus was on legal protection for people displaced across borders in the context of disasters, it evolved into a more comprehensive approach that included disaster risk reduction, planned relocation, and support for adaptation to enable people to stay at home in their country of origin.

The Envoy of the Chairmanship of the Nansen Initiative, Walter Kälin, attributed the Nansen Initiative’s success to its ability to frame core messages and feed them into relevant discussions and negotiations. The socialization of messages on disaster displacement was particularly strong in the Pacific, and through collaboration and consultation with Pacific governments, communities and other partners, the Nansen Initiative and its successor organization, the Platform for Disaster Displacement (PDD), were able to support regional momentum demanding increased legal and policy action. In the policy realm, for example, the 2023 Pacific Regional Framework on Climate Mobility sets out shared priorities for States in the region to respond to the realities of climate mobility.

This momentum gained even more traction when the campaign to bring climate change to the ICJ was spearheaded by a group of students who lobbied the government of Vanuatu to advance the case. Building upon previous attempts by other island nations, in 2023 the UN General Assembly made a consensus-based referral to the ICJ, requesting an advisory opinion on the obligations of States in respect of climate change.

The win

On 23 July 2025, the ICJ delivered its historic Advisory Opinion. It truly exceeded expectations, even for the optimistic human rights lawyers who dedicated years to its preparation.  

While its direct observations on displacement in the context of climate change were brief (para 378), a close analysis of the decision reflects that the habitability of certain areas, and its flipside, movement away from those areas (described here as human mobility), were addressed throughout. In this way, the Advisory Opinion has potentially far-reaching implications for people who are displaced, migrating or relocating, as well as for people who are – willingly or unwillingly – immobile. 

The priorities identified in the Nansen Initiative Protection Agenda are alive and well within the ICJ’s Advisory Opinion – in particular, protection and solutions for people displaced in the context of disasters and climate change, and the integration of mobility in disaster risk reduction and climate change adaptation strategies.  While the Advisory Opinion only briefly addressed the first of these through its analysis of the principle of non-refoulement under human rights law, it dedicated more analysis to the second goal by clarifying the legal obligations owed by States to people adapting in situ, but who might be at risk of displacement. Even though the terms ‘mobility’ and ‘displacement’ are not referenced directly, a close read of the Advisory Opinion reflects that the reality and threat of displacement play a central role in the Court’s examination of other rights and obligations. 

First, the ICJ affirmed existing jurisprudence that the principle of non-refoulement (non-removal to persecution or other serious harm) can protect people displaced across borders in the context of climate change (para 378).

This reflects an evolution in understanding how relevant legal principles apply, as well as the importance of international processes reinforcing and advancing one another. In 2015, the Protection Agenda recognized the in-principle applicability of refugee law and ‘similar protection under human rights law’ in the right factual circumstances, drawing on academic analysis as well as emerging jurisprudence in New Zealand. In 2019, the UN Human Rights Committee affirmed that ‘the effects of climate change in receiving States may expose individuals to a violation of their rights under articles 6 or 7 of the Covenant, thereby triggering the non-refoulement obligations of sending States’ (Teitiota v New Zealand, para 9.11) (drawing on the detailed reasoning of the New Zealand Immigration and Protection Tribunal, which had originally examined the claim). In 2024, multiple State submissions to the ICJ referenced Teitiota, and in 2025, the ICJ formally endorsed its approach.

Second, the ICJ found that ‘a clean, healthy and sustainable environment is a precondition for the enjoyment of many human rights’ (para 393). The Court declined to find a standalone right to a healthy environment, as had been proposed by some States. Yet, positioning a clean environment as a ‘precondition’ for the protection of other basic human rights carries significant weight, particularly when read alongside the Court’s finding that the obligation to prevent significant transboundary harm is an erga omnes obligation (para 440) – one that is owed to the international community as a whole. 

Third, the ICJ recognized that sea-level rise resulting from climate change jeopardizes territorial integrity and creates a risk of displacement, which have direct consequences for the exercise of the right to self-determination (para 357). While displacement was an ancillary consideration here, the acknowledgement that climate change can have dramatic impacts on the habitability of land is clear throughout the Advisory Opinion. In their submissions, many small island States chose not to refer to an ‘existential threat’ of climate change-induced sea-level rise lest that imply that they might lose their sovereignty and statehood – a position that Pacific States, in particular, strongly reject. Indeed, the Court stated that ‘the disappearance of one of [a State’s] constituent elements would not necessarily entail loss of its statehood’ (para 363). Perhaps unsurprisingly, the Court did not speculate as to where people who could no longer reside in their country of origin would go, but its clarification that cooperative action and shared responsibility are collective obligations of States (para 142) would necessarily also apply in the context of displacement and migration management.

Finally, the ICJ admonished States that had not aggressively pursued and financed mitigation of greenhouse gas (GHG) emissions, emphasizing that the Paris Agreement commitment of limiting warming to 1.5 degrees Celsius was not discretionary (para 224 and 234).  This leaves the door open to future legal claims that polluting States are failing their legal obligations.

This finding was directly responsive to the requests by dozens of States that poignantly and clearly argued climate justice demands such recompense. States that are the least responsible for GHG emissions find themselves facing the greatest impacts of climate change, including sea-level rise, desertification, extreme heat and flooding. These climate impacts will either require people to adapt in place or will play a role in their movement elsewhere. Significantly, the Court found that developed States ‘have an additional obligation to assist developing country parties in meeting the costs of adaptation’ (para 268, referring to article 4(4) of the Paris Agreement). The preventative nature of this obligation – to fund anticipatory action so that people do not have to leave their homes – is an important contribution to the jurisprudence on climate mobility.

Additionally, the Court even previewed remedies for breaches by concluding that the responsibility for ‘the loss and damage associated with the adverse effects of climate change, is to be determined by applying the well-established rules on State responsibility under customary international law’ (para 420). Scholars have demonstrated that displacement can function as both loss and damage, and that States must ensure that financial mechanisms account for climate-related displacement.

Conclusion

The ICJ’s Advisory Opinion is a game-changer, clarifying that international law requires States to prevent significant harm to the climate – and that failure to do so can trigger legal responsibility.  The Court linked climate action directly to human rights and human dignity. While the Advisory Opinion made only limited direct references to legal protections for people displaced in the context of climate change, they were by no means insignificant. In particular, a large portion of the reasoning concerns States’ obligations to mitigate GHGs, which are obviously contributing to the impacts of climate change, including displacement.

As climate-impacted States requested in their submissions, the ICJ articulated legal obligations to finance adaptation not only as a response to displacement, but also as a preventative obligation to the threat of displacement. And, as an example of the Advisory Opinion’s potential to drive policy, Vanuatu recently put forth a UNGA resolution endorsing the Advisory Opinion, offering a renewed path for international cooperation and implementation.

The priorities set out in the Nansen Initiative Protection Agenda arguably seeded the ground for the ICJ’s pathbreaking, human-centered engagement with climate action, with the Advisory Opinion giving new life to many of the Protection Agenda’s core recommendations. It is now incumbent upon States, civil society and local communities to determine the best paths to weave these findings into law, policy and practice, so as to shield humanity from the worst impacts of climate change.

Shana Tabak is a Senior Fellow and Director, Climate Mobility at Carnegie Endowment for International Peace.