Pollution or protection? The International Tribunal for the Law of the Sea’s advisory opinion on climate change and its relevance for marine carbon dioxide removal (mCDR)

Abstract In May 2024, the International Tribunal for the Law of the Sea (ITLOS) published an advisory opinion on climate change. Many expected that this decision would help to clarify the balance between the paradigms of ocean protection and utilisation in the context of climate change. This is especially relevant for governing emerging marine carbon dioxide removal (mCDR) approaches being proposed to increase the carbon drawdown potential of the ocean to mitigate climate change. Does mCDR constitute marine pollution or marine protection in the face of climate change? To help answer this question, we analyse the advisory opinion and map the different emerging interpretations of the decision in relation to mCDR. We find that, although the resulting advisory opinion provided clarity on the responsibility of states to protect the oceans from “pollution” by atmospheric CO 2 , it left a lot of room for ambiguity about whether mCDR would constitute marine pollution or marine protection in the face of climate change. We show how this ambiguous decision could be used politically to either promote or prevent problem shifting of the climate problem to the marine environment. We caution that international treaty bodies and national regulatory authorities should be prepared for these different interpretations to play a role in ongoing climate and ocean governance processes.