ICJ Advisory Opinion: Climate Change Is an ‘Existential Threat’, Says World’s Top Court

“The consequences of climate change are severe and far-reaching. They affect both natural ecosystems and human populations. These consequences underscore the urgent and existential threat posed by climate change,” Iwasawa Yuji, President of the Internaitonal Court of Justice, said on Wednesday.

—

The International Court of Justice (ICJ), the principal judicial organ of the UN, is delivering its long-anticipated advisory opinion on the obligations of states in respect of climate change on Wednesday.

Presenting the opinion at the Peace Palace in The Hague, the court’s President Iwasawa Yuji said greenhouse gas emissions are “unequivocally” caused by human activities and acknowledged the “urgent and existential threat” posed by climate change.

“The consequences of climate change are severe and far-reaching. They affect both natural ecosystems and human populations. These consequences underscore the urgent and existential threat posed by climate change,” said Iwasawa.

Before the court’s 15 judges were two fundamental questions: What are states’ obligations under international law to address climate change for present and future generations? And what are the legal consequences under these obligations for states failing to do so?

What follows are some of the main arguments presented by the court.

Lex Specialis

Importantly, the court rejected the lex specialis argument raised by many developed states, which suggests that the specific treaty regimes related to climate change (like the UNFCCC and the Paris Agreement) should be considered as the primary or even exclusive source of law for determining states’ obligations related to climate change.

Big polluters have repeatedly envoked the argument to claim that climate agreements protect them from accountability for climate harms, Sébastien Duyck, Senior Attorney in the Climate & Energy Program at the Center for International Environmental Law, pointed out.

Paris Agreement

In relation to the Paris Agreement, the court affirmed recognized the 1.5C target to be the only relevant limit and recognized that the climate treaty establishes “stringent obligations” for states to protect the climate and other parts of the environment from anthropogenic greenhouse gas emissions.

It also dismissed an argument put forward by big polluters that national climate action plans, known as Nationally Determined Contributions (NDCs), are discretionary. Instead, the court affirmed that NDCs – which states are required to update every five years – must collectively be capable of realizing the objectives of the agreement.

“The court concludes that rather than being entirely discretionary, as some participants argued, NDCs must satisfy certain standards under the Paris Agreement. All NDCs … must, when taken together, be capable of realizing the objectives of the Agreement which is set out in Article 2,” the opinion stated.

Young activists from various climate change-battered Pacific Island nations organized under the Pacific Island Students Fighting Climate Change (PISFCC) launched a global campaign for an advisory opinion back in 2019 as they seeked climate justice and legal pathways to hold big polluters accountable for their actions. For them, an advisory opinion is “the most authoritative and constructive route available for an independent clarification of the legal implications of climate change under international law.”

The Pacific Islands are at the forefront of climate change, threatened by a triple whammy of accelerating sea level rise, ocean warming and acidification despite being responsible for less than 1% of total global greenhouse gas emissions.

Earth.Org’s Editor-in-Chief Martina Igini interviews Vishal Prasad, Director of PISFCC.

World’s Top Courts Increasingly Involved

A growing number of cases, mostly involving government defendants but also corporate defendants, are reaching top courts such as supreme or constitutional courts, according to a recent report by London-based Grantham Research Institute on Climate Change and the Environment.

The ICJ is the third international court asked to clarify states’ obligations on climate change in recent years, alongside the Inter-American Court of Human Rights (IACtHR) and the International Tribunal on the Law of the Sea (ITLOS).

In its May 2024 advisory opinion, the ITLOS – a UN court on maritime law – said carbon emissions can be considered a marine pollutant, and furhter stated that countries must “take all necessary measures to prevent, reduce and control marine pollution from anthropogenic [greenhouse gas] emissions.”

The ruling also made clear that the work of defining countries’ obligations is not limited to the Paris Agreement or the UNFCCC – the UN body on climate change, something that major polluters like the US and China have repeatedly contested while also arguing against courts taking climate-related decisions.

Meanwhile, the IACtHR – Latin America’s top human rights court – ruled that states and corporations have binding obligations under international law to address the climate crisis as a human rights emergency, and placed irreversible climate harms on the same level as internationally-recognized crimes like genocide and torture. Notably, a section of the opinion addressed environmental defenders, affirming states’ binding obligations not only to protect those who defend land, climate, and human rights but also to investigate those acts, punish those responsible, and ensure access to justice.

Experts described the IACtHR opinion as “the most important and progressive document yet released by an international court on the climate crisis.”  

While representing only a small proportion of climate cases, international courts’ opinions, while non-binding, carry significant legal weight and moral authority and are poised to shape the future of climate litigation, informing both domestic courts and international political processes.

The ITLOS ruling was referenced in at least one court proceeding in the UK, though its real impact on climate litigation has yet to be tested, according to the Grantham report.

Featured image: ICJ/ICJ Frank van Beek. Courtesy of the ICJ.

Check out our analysis of the ITLOS and IACtHR advisory opinions.