Mediating Climate Accountability: The ICJ Advisory Opinion and the Role of Mediation

With the Global temperature about 1.1°C above pre-industrial levels and the past nine years the warmest on record, rising seas, melting glaciers, shrinking Arctic ice, intensifying heatwaves, shifting rainfall patterns, and stronger tropical cyclones are no longer distant threats. They are reshaping ecosystems, jeopardizing livelihoods, and straining international relations. Despite overwhelming scientific evidence, public trust in governments, institutions, and global leaders to effectively address the climate crisis is eroding.

In this context, mediation could be a vital tool for rebuilding trust, which is the foundation of social cohesion and collective action necessary for an effective response to the climate crisis. As climate change impacts worsen, the international community is taking notice. On 29 March 2023, the 77^th session of the United Nations General Assembly adopted resolution A/77/L.58, requesting an advisory opinion from the International Court of Justice (ICJ) on the obligations of States regarding climate change — a pivotal step in global accountability.

On 23 July 2025, the ICJ issued a unanimous advisory opinion affirming that States have binding obligations under treaty law, such as the United Nations Framework Convention on Climate Change (UNFCCC), Paris Agreement and United Nations Convention on the Law of the Sea (UNCLOS) as well as customary international law to prevent significant harm to the climate system and environment. The opinion establishes that a clean, healthy and sustainable environment is a precondition for many human rights, such as the rights to life, health and housing.

The Court further declared that failure to act - for example, licensing fossil fuel projects or subsidizing extraction - may constitute an international wrongful act, obliging cessation of harmful conduct and reparation, including cessation, guarantees of non-repetition and full reparation. Whereas directed at states, the opinion stresses that state duties extend to regulating private actors, including corporations and foreign investors, whose emissions fall under their jurisdiction or control. Although the opinion is non-binding, it reinforces existing legal pathways for accountability and reparations. In doing so, the opinion creates a new potential for a negotiated dispute resolution, notably mediation.

Why Mediation Matters in Inter-State Climate Disputes

The ICJ’s advisory opinion underscores that climate change is not merely a legal or environmental issue but a complex and multi-dimensional challenge that implicates equity, development and shared responsibility. Against this backdrop, mediation and other consensual mechanisms under Article 14 of the UNFCCC, which provide for amicable settlement and conciliation, offer a pathway that is consistent with the cooperative spirit envisioned by the Court and the UNFCCC, for the reasons set out below.

1. Flexibility to craft complex and multi-dimensional remedies

The ICJ’s opinion reflects an understanding that climate change harms are diffuse, systematic, and intergenerational. Meaning, they are embedded in societal structures and affect both current and future generations. These characteristics make such harms difficult to address through narrowly defined compensation alone. Mediation offers States a more flexible approach than courts or arbitration, enabling them to craft solutions that respond to immediate climate impacts, such as extreme weather events or air pollution, as well as the structural conditions that amplify these harms, including inequality, limited adaptive capacity, and institutional weaknesses affecting vulnerable communities.

Furthermore, mediation can incorporate debt restructuring or relief measures that free fiscal space for climate change action, reflecting the shared responsibility and differentiated capacities recognized under international climate law. Importantly, mediation provides a forum for States to negotiate guarantees of non-recurrence, such as commitments to emission reduction targets, early warning systems or improved environmental governance, thereby ensuring that remedies contribute not only to redress but also to prevention. In this way, mediation supports holistic, forward-looking settlements that align with the remedial and cooperative dimensions emphasized in the ICJ’s opinion and the UNFCCC framework.

2. Political and reputational space to negotiate beyond zero-sum litigation dynamics

Mediation offers States a political and reputational buffer that litigation rarely provides. In adversarial proceedings, States are locked into rigid positions. Legal claims and defences tend to create zero-sum dynamics, i.e., one party’s success is framed as the other’s loss. This can heighten political sensitivities, strain bilateral relations and limit opportunities for creative or cooperative problem-solving.

By contrast, mediation provides a confidential and less confrontational forum in which States can explore interests, exchange information, and negotiate shared solutions without the public spectacle or reputational risks associated with courtroom battles. This is particularly valuable in the climate change context, where the ICJ’s advisory opinion emphasizes the shared obligations and collective stewardship of the global climate system. Within this normative framework, mediation aligns more closely with the Court’s call for cooperation and mutual accountability.

Through mediation, States can jointly design implementation or remediation mechanisms —such as cooperative adaptation projects, financial or technical assistance schemes, or joint monitoring arrangements that transform legal responsibility into practical collaboration. Such negotiated outcomes not only preserve diplomatic relationships but also demonstrate compliance with the ICJ’s vision of good faith engagement under the UNFCCC and general international law.

3. Science-policy integration and phased dispute management

Per the ICJ’s Advisory Opinion, credible climate governance must rest on a strong link between science and policy. The Court leaned heavily on the latest findings from the Intergovernmental Panel on Climate Change (IPCC) and other scientific bodies to explain what “due diligence” and “best available science” mean in practice. In doing so, it signalled that future climate dispute settlements will need to integrate scientific knowledge and evolve as the science itself advances. This is where mediation stands out, as it’s flexible enough to bring science directly into the process. Expert mediators or advisory panels can help parties understand complex data, and shape fair and practical solutions.

Mediation also allows for phased implementation, where agreed actions can be revisited and adjusted as new climate data or technologies emerge. This kind of adaptive, science-informed process is exactly the kind of cooperative problem-solving the ICJ encouraged. It bridges the gap between legal principles and real-world evidence, ensuring that outcomes are not only legally sound but also scientifically credible and sustainable over time.

Precedents and lessons to borrow

1. Trail Smelter (US-Canada, 1938–41).

The Trail Smelter arbitration case remains a foundational precedent in international environmental law. The arbitral tribunal held Canada responsible for transboundary air pollution caused by a smelter in British Columbia, requiring cessation of the harmful activity and payment of damages to the United States. This decision crystallized the principle that no State has the right to use or permit the use of its territory in such a manner so as to cause injury by fumes in or to the territory of another. The ICJ’s opinion echoes this principle, reaffirming States’ duty to prevent and redress environmental damage beyond their borders. While Trail Smelter addressed a localized bilateral dispute, climate change involves cumulative, global harm. The ICJ’s reasoning suggests that remedies must therefore, extend beyond injunctions and damages toward cooperative and forward-looking measures such as adaptation finance, i.e., funding that helps communities and systems adjust to climate change impacts, such as droughts, floods, and extreme heat by strengthening resilience through measures like flood resistant infrastructure, drought-tolerant crops, early warning systems, and social safety nets.

2. UN and Peace Mediation Practice

The UN’s long experience in peace mediation offers another rich source of lessons. Through “good offices,” facilitation and inclusive dialogue, UN mediators bridge divides that mix science, politics and community interests, which are the kind of complexities that climate mediation involves. The ICJ’s emphasis on cooperation and good faith mirrors this approach. Drawing on UN mediation practices could help States move from confrontation to collaboration, turning climate mediation into opportunities for joint problem-solving, resilience-building and equitable burden-sharing.

Checklist for effective inter-State climate mediations

1. Establish mandate, scope and sequencing

Clarify the legal and relief horizon. Is the mediation to settle claims for past damage (reparations)? To set mitigation commitments? Or to negotiate a package that mixes both? Is it to simply develop cooperative implementation measures? While the ICJ opinion widens parties’ expectations about reparations, the mediator must elicit and record the parties’ expectations at the outset. The mediator should also begin with a joint fact-finding and trust-building phase (involving scientists and independent auditors), then move to negotiation on principles (liability, causation, scope of remedies) and end with implementation and monitoring arrangements.

 Integrate independent technical expertise

As part of the mediation process, a panel of neutral experts should be established, from which the parties can mutually select, such as, climate scientists and economists (joint scientific attribution panel) to produce a transparent, causal assessment of climate related impacts (for example, droughts, floods, or heatwaves) to specific climate drivers or human caused emissions  and damage quantification. This would provide a credible technical basis for negotiations. The ICJ opinion emphasises the need for multi-disciplinary input and mediation should operationalise this.

3. Design multi-track remedies

Composite settlement packages can be structured to facilitate mediation by linking concessions across issues that matter to different parties. For example, packages can include direct compensation, climate adaptation, and resilience investments to address immediate loss and damage, as well as technology transfer and capacity building to support long term autonomy and implementation capacity. They may also include tariff free access for affected exports and debt for climate swaps to create economic incentives that help justify commitments, particularly where fiscal or political space is limited. Joint carbon reduction projects, supported by monitoring from a neutral panel of experts selected by all stakeholders, provide assurance that obligations will translate into measurable outcomes. By bundling these elements, mediators can expand the bargaining zone, balance asymmetric interests, and build consensus, thereby increasing both the political acceptability of the agreement and the likelihood of sustained compliance.

4. Financial architecture and phased payments to intended recipients

Escrow mechanisms and tranche payments tied to verifiable milestones can ensure that funds reach their intended recipients, such as local communities, project implementers, or national agencies, reliably and transparently. In mediation, these phased payments can reinforce trust among stakeholders and in the mediation process as well, as each disbursement (of climate funds, compensation, and project resources) is conditional on verifiable progress, reducing disputes over implementation. Leveraging existing channels, such as the UNFCCC’s loss and damage mechanisms, including the COP27 Loss and Damage Fund, provides mediators with credible, tested structures to coordinate funds while promoting accountability and confidence in the process.

5. Monitoring, verification and dispute-avoidance clauses

Mediation settlement should embed a robust, independently verified monitoring system to track compliance with agreed climate actions and commitments. The monitoring framework must clearly define responsibilities, reporting protocols, and indicators aligned with scientific and policy standards. Settlements should also establish pre-defined triggers for remedial action, specifying which parties act and under what conditions to address underperformance or unforeseen environmental impacts. Additionally, mediation settlements may also incorporate adaptive review clauses, enabling periodic reassessment and adjustment in response to new scientific evidence, emerging environmental risks, or shifts in international obligations. Framed this way, mediation settlements provide a structured, verifiable, and flexible framework, ensuring that inter-State climate commitments remain credible, enforceable, and resilient over time.

Anticipated hurdles and mitigation strategies

The ICJ’s opinion has reshaped global conversation on accountability and cooperation. While the Court’s opinion is not binding, it carries persuasive authority and affirms the States’ duty to prevent and redress climate harm as well as their shared obligation to act in good faith under the UNFCCC and Paris Agreement frameworks. However, turning these broad legal principles into practical cooperation or compensation mechanisms is not straightforward. As States and international institutions begin to interpret and operationalize the Opinion, several hurdles are likely to emerge. Each requires thoughtful mitigation strategies grounded in science, diplomacy and institutional design.

1. Attribution Complexity

One of the toughest challenges is the question of causation. Climate harms rarely trace neatly back to a single source. As the ICJ acknowledged, climate damage is the result of cumulative, multi-factorial processes that unfold over time. This makes traditional notions of liability difficult to apply. To navigate this, States can rely on collective attribution frameworks, for instance, expert panels under the UNFCCC, that assign probabilistic shares of responsibility based on historical emissions and economic capacity. This approach moves away from blame towards shared responsibility models, which is also aligned with the ICJ’s emphasis on cooperation and equity rather than confrontation.

2. Power Asymmetries

Another hurdle lies in the political economy of climate justice. Wealthier and high emitting countries may resist large scale financial, technological, or compensatory transfers (systematic redistribution framed as climate compensation) due to fears of precedent, fiscal exposure, and domestic political opposition. However, the ICJ Opinion underscores that equity and differentiated responsibilities are cornerstones of climate justice (a movement and framework recognizing that climate change disproportionately harms vulnerable communities). Creative design packages that blend technology transfers, green investments and reputational incentives are required to make participation politically palatable. For example, reparative measures could be framed as future investments rather than penalties. This helps align moral responsibility with strategic self-interest. This also reflects the ICJ’s cooperative vision as well as pragmatic realities of diplomacy.

3. Enforcement Fears

Even where mediated settlement agreements are reached, enforcement may remain a concern. Without binding mechanisms, States may worry that others will not follow through or that financial promises will never materialize. The ICJ’s Opinion implicitly recognizes that effective cooperation depends on trust and credible systems for delivering what was agreed. To address this, States can use escrowed funds, independent trustees, or established international financing channels, such as the Loss and Damage Fund or development banks so that money is released only after agreed actions are carried out. By linking funding to performance, these arrangements build accountability into the agreement itself, helping ensure commitments are honoured while preserving flexibility and trust among participants.

 Sovereignty and Precedent Concerns

Many States are cautious about acknowledging (formally) responsibility, fearing that doing so could trigger multiple risks, including legal claims, financial liabilities, reputational damage, political backlash, and creates sensitive precedents that might constrain future actions. The ICJ’s advisory framework provides a practical path forward. It encourages States to act responsibly without imposing a rigid liability model. In practice, mitigating the risks mentioned above requires carefully crafted mediated settlement agreements that clearly define the scope of claims, establish standards for evaluation, and specify exclusions to limit legal, financial, and political exposure. Agreements can also incorporate “without prejudice” clauses, ensuring that participation in discussions does not constitute an admission of fault. While these mechanisms cannot eliminate all risks, they offer States a structured way to respond to the ICJ’s call for accountability while protecting sovereignty and promoting stability.

Concluding challenge: Make the mediation climate-ready

The ICJ’s advisory opinion marks a tectonic shift, elevating expectations of responsibility and reparative justice for climate related damages. This reframes mediation not as a second-best option but as a frontline instrument capable of delivering durable, technically robust, and politically feasible remedies that courts alone cannot achieve.

To seize this opportunity, practitioners should prioritise three immediate actions: (a) develop mediator rosters with climate expertise, integrating scientists, climate economists, and technical specialists alongside conventional mediators; (b) operationalise finance mechanisms aligned with UNFCCC structures to support implementation; and (c) pilot a small number of inter-State mediations to stress-test phased, composite remedies and produce scalable templates for broader application