Climate change goes to court: What the ICJ just told the world

In my opinion
By Prof Daniella Tilbury

On 23 July 2025, something quietly historic happened in The Hague: the International Court of Justice (ICJ) issued its long-awaited Advisory Opinion on climate change. At first glance, this ruling may seem distant from Gibraltar’s shores, decided by judges thousands of kilometres away. Yet in reality, it speaks directly to all of us: to our duties under the law, to our human rights, and to our responsibility to future generations in Gibraltar.

The law is clear: States must act, not just promise

The ICJ has now affirmed what climate lawyers and many of us engaged in policy have long argued for years: climate change is not simply a matter of politics or diplomacy, it is a legal obligation. Countries cannot merely gesture towards action. They cannot satisfy these obligations by words alone. They must adopt concrete measures to reduce greenhouse gas emissions and protect both people and ecoystems.

National governments have already signed up to a web of climate treaties: the UN Framework Convention on Climate Change, the Kyoto Protocol, the Paris Agreement. These are not optional; they oblige countries to limit temperature rise (ideally to 1.5°C) and keep ramping up their ambition to cut down carbon consumption. For Gibraltar, as a British Overseas Territory, these obligations apply under the UK’s international treaty responsibilities.

However, the ICJ went further, reminding us that customary international law also demands action: the shared duty of all states to prevent significant environmental harm, to cooperate globally, and to protect the marine environment from pollution—including greenhouse gas emissions. Strikingly, the Court recognised that these emissions qualify as marine pollution under the UN Convention on the Law of the Sea. For a coastal community like Gibraltar, whose economy, identity and well-being are deeply tied to the sea, this should resonate powerfully.
Climate change is now a recognised human rights issue

Perhaps most significantly, the ICJ underscored that a clean, healthy and sustainable environment is not a luxury - it is fundamental to the realisation of basic human rights, including the rights to life, health, food and housing. The climate crisis directly threatens these rights, and this Advisory Opinion places them firmly at the heart of legal and policy responses.
This is not an abstract argument. In Gibraltar, we already experience hotter summers, shifts in marine biodiversity around the Rock and the Bay, and greater risks to public health, especially among our most vulnerable populations. If the climate change escalates and the environment deteriorates further, it is not just an ecological loss; it is a direct threat to rights protected under the Gibraltar Constitution and international human rights instruments extended to Gibraltar.

The Court also signalled that governments cannot simply adopt plans on paper; they must hold powerful actors, including major industries and polluters, accountable in practice. This reminder carries global significance, but it should prompt local reflection too. The Court made a special nod to small island states whose very survival is on the line, though a few judges wished the opinion had gone even further.

Shared obligations and local responsibility
A particularly notable part of the ICJ’s opinion is its confirmation that climate obligations are erga omnes: they are owed to the international community as a whole. This means any state, even if not directly harmed, may challenge another’s failure to meet its climate commitments. Further, actions such as subsidising fossil fuels or failing to phase out polluting technologies can amount to internationally wrongful acts, which may carry legal consequences, including reparations.

Gibraltar has historically been carbon-intensive as it continues to rely heavily on fossil fuels. The old power stations were diesel-fired until new LNG-powered generation started coming online around 2021, which has reduced but not eliminated emissions. LNG is essentially methane (CH₄), which is a powerful greenhouse gas that has significant upstream emissions. Gibraltar will need to move beyond LNG to truly low-carbon energy sources. Its economy also includes activities such as shipping and bunkering that explain why Gibraltar has one of the highest global carbon footprints per capita.

For Gibraltar, this should lead us to ask hard questions: Are our climate pledges sufficiently ambitious and actionable? Is there effective regulation of local emissions and industries? Are we moving beyond declarations and commitments under the Climate Change Act, to visible and measurable implementation? Are we sufficiently exploring greener fuels and power generation alternatives to sustain our economy? The ICJ has made it clear: complexity, constitutional status or small size do not excuse inaction.

Why this matters to Gibraltar
Although Advisory Opinions are not legally binding in the same way as judgments in contentious cases, they carry significant legal and moral authority. They provide judges, lawmakers and civil society with a firmer legal foundation to demand meaningful climate action. Importantly, the ICJ has now connected environmental law, human rights law and climate treaties into a clearer, more coherent legal framework.

For Gibraltar, this is not merely about aligning with international expectations or reputation management. It is about our legal and ethical duty to protect the sea and land that define us; to uphold the rights and health of current Gibraltarians; and, to safeguard the wellbeing of future of generations who will call the Rock home.
As Judge Yuji Iwasawa reflected, legal clarity is vital, but the ultimate solutions still rest on collective human will and wisdom. With the world’s highest court speaking unequivocally and plainly, the case for delay, denial or purely symbolic action has become harder to sustain - even from our small but globally connected corner of the Mediterranean.

Prof Daniella Tilbury is the UK’s focal point at the UN Economic Commission for Europe, an adviser to the European Commission on the Green Transition, and Climate Ambassador for the city of Girona. She has chaired UN dialogues at COPs, High-Level Political Forums in New York and served as Gibraltar’s Commissioner for Sustainable Development and CEO of the University of Gibraltar. Daniella supports government, business and education organisations in their transition to more sustainable futures.