The ICJ Just Raised the Bar on Climate Obligations

Here’s Why That Matters for Your Organisation

On 23 July 2025, the International Court of Justice (ICJ) handed down a landmark Advisory Opinion on climate change.

It’s 140 pages long, the most participatory case in the Court’s history, and – for the first time – it draws together science, human rights, and international law into one clear message:

climate action is a legal duty, not just a policy choice.

For governments, this sets a new legal context. For councils, heritage organisations, and estate owners, it signals that domestic law, planning, and funding priorities will shift – and quickly.

1. The 1.5 °C Limit Is Now the Legal Standard

The Court treated 1.5 °C of global warming as the operative benchmark for interpreting climate duties.

That means:

• National and local policies must align with pathways that keep us within that limit.

• Planning decisions, Environmental Impact Assessments, and infrastructure approvals will face closer scrutiny against this target.

• Token targets are out – due diligence in achieving measurable reductions is in.

2. Support for the Most Vulnerable Is Binding

Developed states – including the UK – have a legal obligation to provide finance, technology, and capacity to developing nations.

This isn’t just foreign policy. Expect this principle to influence funding streams, climate finance priorities, and eligibility for public grants at home.

3. Customary Law Extends Responsibility

Even outside treaty commitments, states must:

• Prevent significant harm from activities under their control (including emissions from supply chains).

• Regulate private actors whose activities contribute to climate impacts.

• Cooperate internationally – a duty that will echo through regional partnerships and cross-border conservation projects.

4. Oceans and Coastal Protection Are on the Legal Map

The Court recognised greenhouse gases as pollutants under the UN Law of the Sea.

For coastal estates and island communities, this reinforces obligations to protect marine ecosystems and collaborate on adaptation to sea-level rise.

5. Human Rights and Climate Are Interlinked

The ICJ placed climate change firmly within the scope of rights to life, health, and adequate living standards.

For public bodies and land managers, this strengthens the link between climate resilience measures and legal compliance on equality, accessibility, and safeguarding.

What This Means for You

This opinion won’t sit on a shelf. It will:

• Inform UK planning and environmental law updates.

• Increase litigation risk for projects that ignore emissions pathways or adaptation needs.

• Shape funding priorities towards projects with clear, measurable climate benefits.

• Give communities and NGOs stronger legal footing to challenge decisions that undermine resilience.

Our View at Resilient Horizons

We see this as a turning point.

It’s an opportunity for organisations – from heritage estates to local authorities – to future-proof their operations, integrate climate obligations into every decision, and demonstrate leadership before regulation demands it.

If you manage land, heritage assets, or community infrastructure, this is the moment to:

• Reassess climate strategies against a 1.5 °C pathway.

• Strengthen due diligence in planning and asset management.

• Build partnerships that meet both mitigation and adaptation goals.

Resilient Futures aren’t built by accident – they’re planned.

This ICJ ruling just made that planning a legal necessity.