Analysis | Law of the Sea climate diplomacy can do what COP27 could not. Here’s why.

Matthew Carvalho

(Image: Jeremy Bishop on Unsplash)

On December 12, 2022, after a year of preparation, the Commission of Small Island States on Climate Change and International Law (COSIS) submitted a request to the International Tribunal for the Law of the Sea (ITLOS) for an advisory opinion on how to interpret climate change impacts under the 1982 United Nations Convention on the Law of the Sea (UNCLOS). Issued by COSIS co-chairs Tuvalu and Antigua and Barbuda, the request aims to determine the obligation under Part XII of UNCLOS for parties to preserve and protect the marine environment, specifically regarding ocean acidification, sea level rise, and other factors that climate change has directly influenced. If successful, small states parties could hold larger ones responsible for emitting greenhouse gasses at high rates, arguing that they have harmed the marine environment.

Although seen as unprecedented, the advisory opinion represents a strategic legal approach through which the most vulnerable countries can move forward on climate change mitigation. Implemented effectively, a climate change litigation case under the ITLOS has the chance to equitably fight increases in greenhouse gas (GHG) emissions in ways that COP27 hoped, but ultimately failed, to achieve.

Following a meeting of the commission members on August 26, 2022, COSIS referred two legal questions to the tribunal: 1) what are the obligations of parties under UNCLOS to “prevent, reduce, and control pollution of the marine environment … caused by anthropogenic greenhouse gas emissions;” and 2) what are the obligations of parties to “protect and preserve the marine environment in relation to climate change impacts.” The tribunal, under Article 21 of its statute, has the jurisdiction to give an advisory opinion on these legal questions, particularly given its duty to oversee all disputes and applications submitted under the Law of the Sea.

Since climate change was not a concern of most countries in the 1980s, as the global impacts had yet to be seen, there is no direct statement regarding climate change mitigation within the text of UNCLOS. Part XII of UNCLOS, titled “Protection and Preservation of the Marine Environment,” outlines that parties have a general obligation to “protect and preserve” the greater marine ecosystem, while also taking necessary measures to “prevent, reduce and control pollution of the marine environment from any source.” In 1982, when the parties adopted UNCLOS, they mainly understood this obligation as a safeguard from shipping waste and other vessel contaminants that could harm marine life.

However, while drafting the convention, negotiators made it clear that they wanted the Law of the Sea to “stand the test of time,” as they knew much of the seas had not been explored and that there were still many hurdles to overcome. As a result, they crafted the language to allow for wide interpretations that could account for unforeseeable problems and disputes. In an era where international law and diplomacy were not nearly as fragmented as in the twenty-first century, the UNCLOS negotiators left open an opportunity, one that COSIS now has promptly taken advantage of.

The strengths of UNCLOS compensate for the limitations of recent international efforts on climate change. For example, agreements such as the United Nations Framework Convention on Climate Change (UNFCCC) and the 2015 Paris Agreement do not have binding dispute settlement procedures, which allow for one party to bring a case to an international court or tribunal against another. Fortunately, UNCLOS, seen as a convention related to climate change mitigation efforts, does. Therefore, COSIS could succeed in convincing the ITLOS to interpret the effects of climate change under the Law of the Sea.

Since most members of COSIS are small island developing states (SIDS), they have the most to lose from GHG emissions as sea level rise continues to engulf their shores. For SIDS, climate change diplomacy is a matter of existence, and the urgency of their circumstances is high. If litigators managed to win such a case, high-polluting countries that signed UNCLOS would be bound under the treaty to lower their emissions. This would give SIDS a unique opportunity to fortify national regulations of GHG emissions on a global scale without falling victim to political obstacles.

At COP27 in Egypt, there were calls for new financing mechanisms, ecological reparations, and an equitable approach to combating climate change and protecting the environment. However, since UNFCCC and the Paris Agreement are not binding, and all nationally determined contributions to reducing GHG emissions are voluntary at best, there is not much diplomatic leverage for SIDS and other countries disproportionately impacted by climate change to work from. The accusations of “greenwashing” from Greta Thunberg and other environmental activists were valid, as no diplomat in Sharm el-Sheikh had the capacity to press another country to adhere to stricter regulations. Although COP27 and its predecessor in Glasgow received substantial attention, much of international environmental law is not equipped with the backbone needed to gain traction on ecosystem preservation.

The advisory opinion request to the ITLOS, on the other hand, puts climate diplomacy under a legally binding mechanism. With both high-income countries and SIDS as parties to UNCLOS, interpreting climate change mitigation efforts under Part XII of the convention offers countries struggling to fight sea level rise an equitable and actionable chance to force polluting countries to comply with their pleas.

The legal fight at the tribunal would require a complex diplomatic strategy to succeed, but experts on UNCLOS see the objective as “not insurmountable.” Each step in the case process would have to be carefully assessed and conducted: deciding which country should bring the case, which country the case should be brought against, the jurisdiction and admissibility of the case, and the forum selection would all be crucial components to the success of the litigation. Nevertheless, UNCLOS experts have concluded that the right legal approach has the potential to result in a positive outcome. Some advancement was already seen with the 2013–16 South China Sea Arbitration brought by the Philippines, which called for an “expansive interpretive approach” to the Law of the Sea. For this reason, COSIS and the ITLOS advisory opinion request have a real opportunity to positively influence climate change mitigation in a way that no COP will likely be able to.

Oftentimes, the answer to diplomatic progress has been more treaties, more negotiations, and more conferences. This outlook neglects to consider the tools and mechanisms we already have in place. Within climate change diplomacy, the ITLOS advisory opinion is a solid path toward GHG emissions reduction through the lens of equity, a concept that caused so many negotiations in Egypt to falter. The innovative approach of COSIS has placed climate change diplomacy squarely in the court of small island developing states. Hopefully, the global community chooses to respond to their ingenuity in kind.



The Diplomatic Pouch features insights and commentary on global challenges and the evolving demands of diplomatic statecraft. Views are those of the authors and not necessarily the Institute for the Study of Diplomacy or Georgetown University. Visit for more.

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