By Shana Tabak, Georgetown University, Institute for the Study of International Migration

This December, as States present their oral arguments before the International Court of Justice (ICJ) in the advisory opinion (AO) on the obligations of States in respect of climate change, the concept of climate mobility will be central to the hearings. While a third of the written submissions specifically reference climate mobility, all State submissions acknowledge the severe and multitudinous ways in which the climate crisis is dramatically reshaping habitability on our planet.

The Court will likely hear testimony about people whose homes have been submerged due to rising sea levels, those who have been unable to predictably grow food as temperatures get too hot and need to relocate to find food, those who have been displaced as floods inundated their neighborhoods, and those who have lost their homes and all their worldly goods in rapid-onset climate events such as fires, floods, or hurricanes.

This article explores why climate mobility is central to the legal framing of the AO and how the Court’s decision might address the role anthropogenetic climate change plays in determining where and how humans live on our planet.

ICJ AO: An opportunity

The ICJ AO represents a long-awaited opportunity for the world’s highest court to deliver a decision to clarify countries’ legal obligations under international law regarding climate change. Over the past several years, a Pacific islander youth-led movement to seek legal accountability has gained momentum, culminating in a consequential unanimous vote by the UN General Assembly (UNGA) to refer the case to the World Court.

While a decision rooted in international law may feel detached from everyday life, the potential impacts are significant. As evidenced by the lackluster financial pledges emerging from the Baku Climate Change Conference (UNFCCC COP 29), there exists an enormous lacuna between the actions that science demands humanity take to avert the worst impacts of global warming and the commitments that States have adopted at international climate negotiations.

An ICJ AO could serve as a guidepost for policymakers in future negotiations. With the ICJ as the UN’s top judicial body, it will provide a reference point for future multilateral negotiations on how to interpret not only the UNFCCC and the Paris Agreement on climate change, but also other international law that relates to climate. A forward-leaning, strongly worded ruling may drive consensus and light a fire for States regarding the need to supercharge mitigation and adaptation commitments, both from a policy and financial perspective.

While ICJ advisory opinions are not binding, they impact policymakers on a global scale and create the opportunity to ground climate diplomacy amidst clarified legal obligations. Thus, the ICJ AO marks an important avenue for achieving more tangible results in the fight against climate change. Hearings can function as a forcing mechanism, demanding that States articulate their positions on legal obligations prompted by climate change. These statements will function as important benchmarks demonstrating to the global community how far States have come or how far they have yet to go in fulfilling their climate commitments. 

Understanding the climate and human mobility nexus

One of the most transformative impacts of climate change has been, and will be, that of climate mobility. As early as 1991, the Intergovernmental Panel on Climate Change (IPCC) warned that displacement could be the worst impact of climate change. Indeed, in 2024 it has become abundantly clear that climate change drives or accelerates the movement of people within and across borders.

Climate mobility is interwoven into all aspects of climate change and therefore, as part and parcel of our changing climate, humans will move to find safety and dignity. As the IPCC has indicated year after year, climate change can make the places that we call home too wet, too rainy, too hot, or too dry to survive. As sea levels rise, as growing seasons shift, as weather patterns alter, communities across the globe are forced to reconsider how to adapt to climate change in order to stay in their homes, or to move to a place where they can safely survive its impacts. 

The phrase ‘climate mobility’ functions as an umbrella term used by experts to refer to a broad continuum of people whose habitats are affected by the climate crisis. Climate mobility is understood by experts to include three types of movement: 1) migration, or willing movement within or across borders; 2) displacement, forced movement within or across borders; and 3) planned relocation implemented by State actors to relocate a population to avoid the detrimental impacts of climate change. 

Arguably, climate mobility also includes a fourth category – immobility. Some people are immobile because they do not have the resources to move away from climate impacts. Others are immobile as they refuse to leave due to longstanding cultural linkages to land. Others still are immobile because they have the financial resources to survive climate impacts despite living in a place that might otherwise be uninhabitable.

These categories, however, are not fixed. For example, a family may be displaced by a hurricane and understand that displacement to be temporary, later to discover that the cost of rebuilding their home is prohibitive. What was thought to be a temporary short-term displacement may easily become long term or permanent climate displacement.

For these reasons, climate mobility is a complex category to define. It is multi-directional, multi-causal, and multi-factored. Climate displacement can be the result of rapid onset events such as hurricanes, floods, or fires. It can also be related to slow-onset impacts, including rising sea levels, drought, desertification, or changing weather patterns.

People respond to these sorts of stimuli in varied and unpredictable ways, depending on their financial capacity to move, on their resources to stay and build resilience and adapt to climate impacts, and, of course, on the vagaries of human decision-making processes. At the end of the day, most people do not want to leave their homes because of the climate crisis. Therefore, a key takeaway on climate mobility is that law and policy must support the right of people to stay – and adapt in situ.

Although some people move across borders due to climate events, data indicate that most climate movers are internally displaced. The Court must foreground this reality in its understanding of climate change impacts on habitability. States must be aware of their obligations to climate movers within their borders, as well as to those who may arrive across borders. 

Why should the ICJ AO address climate mobility?

Although the two questions posed to the Court do not directly reference climate mobility, the ICJ will find itself hard-pressed to avoid discussion of this phenomenon, as climate migration implicates a complex tapestry of already existing legal obligations. Notably, the preambular paragraph of the UNGA referral to the Court mentions the impacts of climate “leading to displacement of affected persons,” with reference to food security, water, and livelihoods. Furthermore, nearly a third of the countries who submitted written statements specifically mentioned some aspect of climate mobility, reiterating that the Court should explore the legal obligations connected to climate mobility. Vanuatu, the Pacific island nation that brought the petition to the UNGA, has forcefully articulated the necessity of the Court addressing climate mobility, both to support people who want to stay and to support those who must make the difficult decision to move. 

First, climate displacement is a current reality for some, and clearly foreseeable for others. This is not a challenge of the future; it is today’s challenge. For example, in Solomon Islands, five islands have already submerged due to rising seas and erosion. It is incumbent upon the Court to address this very tangible impact of anthropogenic climate change, and as it considers the obligations of States to affected populations, it must consider climate mobility as one of the central modalities in which climate change affects populations. Any AO analyzing human rights law, statehood, or self-determination that ignored the relationship between climate and mobility would be severely lacking material aspects of the necessary legal analysis.

Second, while climate change affects habitability and, in turn, the mobility of many people, the Court has an opportunity to acknowledge that climate mobility is not a foregone conclusion. The Paris Agreement and UNFCCC highlight that mitigation and adaptation efforts – with their accompanying financial implications – can mitigate the drivers of climate mobility. Follow-through on these commitments may allow people to build resilience and adapt to climate change, decreasing the pressures that drive people from their homes and preserving community integrity and stability. The Court has an opportunity to emphasize the obligation to take preventative – rather than responsive – action to prevent worsening impacts of climate change. Preventative obligations must include aggressive mitigation – but will also necessarily require that States commit to averting, minimizing, and addressing climate-related displacement.

Third, climate mobility intersects with a variety of regimes of international law which may not be immediately obvious. Clearly, climate mobility demands the Court explore the applicability of the 1951 Refugee Convention with respect to climate change-affected people. But the Court can and should dive much more deeply into the legal matrix of climate mobility, including preventative obligations, responsive obligations including disaster law and humanitarian law, as well as cooperative obligations. Climate mobility provides a lens with which to better understand these intersecting sets of legal obligations incumbent upon States.

A final rationale for why the Court should address climate mobility relates to the way in which mobility intersects with climate justice, or the recognition that climate impacts are often felt most acutely by the communities least responsible for global warming. These affected communities are often those with the most limited financial resources to either choose to stay and adapt, or to migrate. A recognition of the disproportionate impact of anthropogenic climate change on impacted communities could lend force to the actors working to unlock climate finance through the Loss and Damage Fund and other climate finance.

What might the ICJ AO find regarding climate mobility?

The Court has numerous opportunities to clarify the legal obligations of States vis-à-vis affected communities across the climate mobility continuum. The opinion may provide legal guidance to both better allow communities to remain safely in their homes and adapt to changing climate, or to protect their choice to safely move away from locations that are uninhabitable due to the climate crisis.

In addressing how to help people stay and adapt in situ, the Court could explore how States’ obligations under the Paris Agreement and UNFCCC to prevent displacement in the context of climate change are accompanied by obligations on non-discrimination. Additionally, sources of law including humanitarian and disaster law demand that States respond to climate-related disasters. If complied with, these could impact peoples’ legal ability to return to their homes, to be relocated close to home, or to participate in planned relocation when a State anticipates it is necessary to preserve human rights. A forceful reminder of the human rights obligations States have toward internally displaced people in the context of the climate crisis would also be a welcome clarification, and one that is firmly rooted in already-binding law.

In addressing how to help people displaced by climate change to safely and humanely move, the Court should address how to better integrate climate-related impacts into a conventional analysis of existing refugee and human rights law. Because climate movers are most frequently internally displaced, climate migration may place significant pressure on States’ already existing obligations under human rights treaties. As various State submissions explain, climate pressures on the right to life, freedom from discrimination, freedom of expression, Indigenous rights, and numerous other basic human rights are complicated by climate-related movement.

In addition to these basic human rights, most human rights treaties incorporate the principle of non-refoulement – the concept that a State is prohibited from returning a person within its boundaries to a person’s home State where that person may risk persecution or serious harm. Scholars and human rights tribunals have grappled with the question of how imminent the harm of climate change must be in order for the obligation of non-refoulement to apply. The Court might explore this question, informed by the UNGA referral’s noteworthy reference to preventative obligations vis-à-vis future generations.

While some tribunals have endorsed the concept of non-refoulement as protecting only individuals who face “imminence of harm,” the Court has an opportunity to adopt a more anticipatory approach. As argued by preeminent refugee law scholars, due to the scientific certainty that anthropogenic climate change will fundamentally reshape the habitability of the places so many people call home, a more appropriate analysis will adopt a foreseeability approach, necessitating protection when there exists a well-founded fear or real risk of harm in the “reasonably foreseeable future.”

Because the majority of climate migrants are internally displaced, these people are unlikely to fall under the nexus of protections afforded by the 1951 Refugee Convention, which remains an important but overstretched binding protection framework. The Court might therefore seize the opportunity to encourage State commitment to soft law frameworks articulating more ambitious and comprehensive systems of human-centered migration management, such as the Global Compact for Migration and the Guiding Principles on Internal Displacement. 

Understanding obligations to present and future generations affected by climate mobility

The questions posed to the Court specifically demand that it opine on State obligations vis-à-vis “peoples and individuals of the present and future generations affected by such adverse effects.” States – in their written submissions and oral interventions – are certain to remind the Court that States owe future generations innovative, bold, and creative guidelines as they will surely be forced to grapple with the uninhabitability of the previously inhabitable areas caused by climate change. Scientists have already confirmed that 2024 is the year when warming temporarily hit the 1.5ºC rise in global average temperature above preindustrial levels. That future generations will be forced to grapple with significant climate migration within and across borders is all but a foregone conclusion.

As a global community, we are woefully underprepared to grapple with the impacts of the climate crisis on the places we call home. The focus must be on stabilizing, supporting, and ensuring the resilience of affected people, whether they are at risk of climate displacement, already on the move, or would prefer to remain in their homes.

The ICJ has a unique opportunity to call attention to one of the most consequential impacts of the climate crisis. As the Court responds to the UNGA’s request for an advisory opinion, it must tackle the reality of climate mobility and seize the opportunity to clarify its relevance within existing legal obligations.

* * *

This Guest Article is part of a project that seeks to raise awareness and build momentum and knowledge around the ICJ advisory opinion on obligations of States in respect of climate change and to promote a better understanding of the implications of the advisory opinion among sustainable development decision makers.