ICJ opinion on climate obligations: Historic signal for states
The Court clarified that protecting the climate system and the environment from anthropogenic greenhouse gas emissions is an obligation towards the entire international community (erga omnes).
The opinion contains far-reaching statements – not only with regard to the responsibilities of states, but also with consequences for the business activities of companies. It has the potential to significantly shape how international legal standards in the areas of climate change and environmental protection are interpreted and applied and could therefore have a lasting impact on the legal framework worldwide. With this opinion, the ICJ has added to a growing list of international decisions that point to increased legal oversight of the conduct of states, and increasingly of companies, regarding climate affairs.
Starting point: UN General Assembly request
The opinion is based on a request from the UN General Assembly to the ICJ (resolution 77/276), which raised two central questions:
- What international obligations do states have to protect the climate system from anthropogenic greenhouse gas emissions in order to safeguard the livelihoods of present and future generations?
- What are the legal consequences if a state causes significant climate damage through its actions or failure to act – especially with regard to small island states and affected populations?
The legal bases referred to include the UN Charter, the International Covenant on Civil and Political Rights and the Paris Climate Agreement. The hearings, which kicked off in The Hague in December 2024, brought together a broad community of states and international organisations – from particularly vulnerable island states to major emitters such as leading economic powers. Numerous states, associations and specialist bodies took the opportunity to offer their legal opinions and scientific analyses. The court also allowed contributions covering a broad range of scientific expertise to ensure that the complex scientific principles and multi-faceted consequences of climate change were fully incorporated into the legal assessment.
As a result, the ICJ not only affirmed its jurisdiction to answer these questions but also presented an opinion with remarkable clarity.
The benchmark: Duty of care, cooperation and duty to protect
In the ICJ's view, the duty to prevent significant environmental damage, which arises from customary international law, is of key importance. This obligation also applies to the climate system – despite the diffuse, cross-border causes of climate change. States must therefore act with due diligence, formulate their nationally determined contributions (NDCs) under the Paris Agreement and implement them effectively.
In addition, the ICJ confirms the duty of international cooperation, including financial and technological support. It also emphasises the requirements derived from human rights – such as the right to life, health and a clean environment.
The Court emphasises that compliance with these obligations is relevant not only politically, but also legally.
Legal consequences: Breaches entail responsibility
In the event that these obligations are breached, the ICJ refers to the system of state responsibility. This includes:
- duties of performance,
- duties of cessation and guarantees of non-repetition and
- duties to make reparation, for example in the form of compensation or satisfaction, provided that there is a sufficiently direct and specific causal link between the act taken or ceased in violation of international law and the damage – a standard that the ICJ consciously applies flexibly to climate damage.
Although the opinion does not contain any binding decision, its arguments have a legal signalling effect.
Companies at a glance: Implementation of duties at national level
Even though the opinion is addressed exclusively to states under international law, it has an indirect effect on economic operators. National legislatures, authorities and courts will be guided by the standards developed by the ICJ in the further development and application of existing legal norms – for example in environmental and climate protection law or in corporate due diligence obligations. At the same time, the ICJ opinion is often understood to mean that states are required to regulate private operators more effectively – a signal in favour of noticeably stricter sector-specific regulations.
The standards developed by the ICJ – in particular the precautionary principle and the duty to avoid significant climate damage – are likely to serve as a guide for assessing corporate conduct in future court proceedings. This not only indirectly increases the liability risk, but also the probability that self-imposed climate targets will become legally enforceable standards. As a result, more proceedings against companies can be expected – from greenwashing and disclosure issues (including prospectus and consumer protection law) to attacks on projects under planning and approvals law.
This reflects recent developments in Germany: In our article on the Lliuya/RWE proceedings before Hamm Higher Regional Court, we show how civil courts are dogmatically making climate liability more stringent and actionable (to the blog post).
International trends towards legal climate responsibility are emerging even beyond the RWE proceedings: In November 2024 the Court of Appeal in The Hague overturned the spectacular first-instance judgment against Shell, thus denying a direct claim for far-reaching emission reductions to be made. At the same time, the European Court of Human Rights found in April 2024 in the case of KlimaSeniorinnen Schweiz that the European Convention on Human Rights had been violated due to insufficient climate protection – thus emphasising the human rights dimension of states' climate-related obligations. Both decisions make it clear that, although the courts emphasise different elements, there is a clear overall trend towards increased judicial oversight of the climate behaviour of states and companies.
What is more, investors, supervisory authorities and NGOs are increasingly demanding robust, consistent and transparent climate reporting. As a result, ESG and climate promises are coming under closer scrutiny – both in legal terms and with regard to reputational and market risks. Companies that are quick to adapt their governance and risk management systems not only can fulfil regulatory requirements but also can secure strategic advantages. In addition, being proactive can facilitate access to climate financing, green bonds and ESG-oriented investors – thus opening up new scope for sustainable growth.
Conclusion: Not binding, but legally authoritative – and economically relevant
The opinion is a milestone in climate law: Although it is not legally binding, it has a considerable effect in the guidance it provides and sets actionable standards for states – with significant economic implications.
For companies, this means that climate responsibility is rapidly becoming an integral part of a binding legal framework. Organisations that are quick to establish resilient governance structures, effective climate risk management and transparent reporting can minimise liability and reputational risks while securing strategic advantages. The international pressure to effectively manage climate risks is growing – and forward-looking actions are becoming a decisive competitive factor. If operators act now, they will not only be setting their own course for climate affairs – they will also be setting standards for the markets of tomorrow.
