International Tribunal for the Law of the Sea Issues Historic Guidance on Climate Change in International Law

Statements by Drs. Shaina Sadai and Carly Phillips at UCS

Published May 21, 2024

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WASHINGTON—The International Tribunal for the Law of the Sea (ITLOS) issued a historic Advisory Opinion (AO) today unanimously affirming that countries must “take all necessary measures to reduce, prevent and control” human-caused heat-trapping emissions. The court’s ruling also asserts that national governments party to the United Nations Convention on the Law of the Sea have a legal obligation to support developing states in addressing carbon pollution, aligning national policies with international climate agreements, and protecting and preserving marine ecosystems. The ITLOS decision is the first of several anticipated AOs from international courts, including the International Court of Justice (ICJ) and the InterAmerican Court of Human Rights (IACHR). While the United States has not ratified the Law of the Sea, as the largest historical emitter of carbon emissions it should take this ruling seriously and act accordingly.

In every region of the world, people are suffering the effects of loss of life and cultural heritage, rising poverty, and property damage due to the impacts of climate change. But those impacts are not equally spread. For example, research led by Dr. Shaina Sadai, a Hitz Fellow for Litigation-Relevant Science at the Union of Concerned Scientists (UCS), found that Antarctic contributions could lead to future sea level rise along the coastlines of Alliance of Small Island States (AOSIS) members up to 33% higher than the global average. The impacts from sea level rise being experienced by AOSIS members are a climate injustice as those countries have contributed almost no heat-trapping emissions to the environment. The ITLOS decision, as well as pending decisions from other international courts, will play a critical role in ensuring accountability and climate justice for communities around the world.

Below is a statement by Dr. Shaina Sadai at UCS.

“The ITLOS Advisory Opinion is a crucial step forward in the pursuit of climate justice. The impacts of climate change are all around us as marine heatwaves are experienced across the world and sea levels continue to rise. In this context, island nations have led the way looking for solutions and today their initiative has secured an Advisory Opinion on climate change and international law focusing on the marine environment. The ITLOS Advisory Opinion provides critical clarity around nations’ legal responsibility that could ultimately help communities secure justice for the detrimental impacts of climate change they’ve already endured and to protect future generations.

“With the official input from an international court, there is significant new legal rationale for thousands of climate litigation cases currently filed in local, state, national and international courts. The ITLOS decision also sets a powerful tone ahead of forthcoming AOs from the International Court of Justice and InterAmerican Court of Human Rights.

“While this progress is hopeful, real climate justice cannot be achieved unless wealthy, high-emitting countries work to meet all specified requirements. It’s deeply unfortunate that the United States isn’t a party to the U.N. Convention on the Law of the Sea but remains crucial that as the world’s largest historical emitter of carbon emissions they do their part in preventing, reducing, and controlling heat-trapping emissions by phasing out fossil fuels and reining in other sources of human-caused heat-trapping emissions. With this new legal reinforcement, the international community is one step closer to ensuring that necessary collective action is taken to address this worsening and grossly inequitable global crisis.”

Below is a statement by Dr. Carly Phillips, a research scientist at the Science Hub for Climate Litigation at UCS.

“I’m encouraged by the ITLOS ruling, which reaffirms the critical responsibility of state parties to mitigate marine pollution from human-caused heat-trapping emissions. The historic failure to curb these emissions thus far has exacerbated deadly climate impacts for everyone but has disproportionately affected the economies and livelihoods of people in small island nations and countries in the Global South.

“This unanimous decision highlights the urgency of adopting rigorous measures to protect and preserve our marine environments from the adverse effects of climate change. The tribunal understood and took into account robust science to make their decision and reflected the need for nations to do the same. The advisory opinion sets a stringent standard of due diligence and is a significant step forward in our collective efforts to safeguard the health of our oceans and the future of vulnerable island nations.”

To speak with Drs. Sadai or Phillips please contact UCS Communications Climate and Energy Media Manager Ashley Siefert Nunes via email at [email protected] or by phone at +1 952-239-0199.

Additional UCS Resources and Analyses:

  • A UCS blogpost by Dr. Merner, the lead scientist at Science Hub for Climate Litigation at UCS, “The Human Right to a Stable Climate.”
  • A UCS blogpost by Dr. Merner, “Can International Law Save the Planet from Climate Change?”
  • A UCS blogpost by Dr. Phillips, “Climate Change Accountability: How International Courts Can Drive Climate Action.”
  • A UCS blogpost by Dr. Merner, “A Call for Climate Justice at the InterAmerican Court of Human Rights.”
  • A UCS blogpost by Dr. Sadai, “Rising Seas, Rising Stakes: The Case for an International Court of Justice Advisory Opinion.”
  • A UCS blogpost by Dr. Sadai, “Do Paris Agreement Temperature Goals Address Sea Level Rise and Climate Justice?”