The International Tribunal for the Law of the Sea (ITLOS) issued an advisory opinion on May 21, 2024, in response to a request submitted by the Commission of Small Island States on Climate Change and International Law (COSIS). While various aspects of the advisory opinion have already been discussed in this joint blog symposium, this post focuses on a feature of the opinion that has so far received little emphasis: the strong role of science in the advisory opinion. Scientific reports on climate issues, as well as reports on the state of the ocean, its ecosystems, and the relevance of the ocean for climate change, play a central role in the opinion. In the remainder of this post, I discuss the process that led the tribunal to base the opinion on the various scientific reports consulted and argue that the use and interpretation of scientific research can facilitate and improve court decisions. In the context of this advisory opinion, ITLOS utilizes climate science to clarify a number of concepts, to classify and prioritize the legal problems posed, and to make its opinion more robust and assertive in the context of the climate emergency.