The International Tribunal on the Law of the Sea (ITLOS) today published its long-awaited advisory opinion on climate change. The opinion was requested in 2022 by the Commission of Small Island States on Climate Change & International Law, which asked ITLOS to opine on States obligations to address climate change under the United Nations Convention on Climate Change (UNCLOS). In today's opinion, ITLOS made some big pronouncements. In this post and the comments below, I share a few that stood out to me when reading the 153 page opinion. For a more detailed discussion, check out the Sabin Center’s Climate Law Blog where, over the next week or so, we’ll be posting a series of reflections on the opinion from legal experts across the globe. (1) Anthropogenic GHG emissions into the atmosphere constitute “pollution of the marine environment” within the terms of UNCLOS. That is something legal scholars & others have long argued but ITLOS has not directly said until now. (2) States have an obligation under UNCLOS to take “all necessary measures” to prevent, reduce, & control marine pollution. In the context of climate change, this means reducing emissions. There is little discussion in the ITLOS opinion of the need for GHG removal. The possibility of “marine geoengineering” is mentioned once in a fairly negative way. ITLOS opines that “marine geoengineering would be contrary to [UNCLOS] if it has the consequence of transforming one type of pollution into another.” ITLOS also notes that marine geoengineering has been the subject of “discussions and regulations in [other] fora” (eg, under the LC/LP), perhaps suggesting that the judges see those treaties as the right place to address mCDR and other similar activities. (3) States cannot satisfy their obligations under UNCLOS “simply by complying with the obligations and commitments under the Paris Agreement.” But the temperature goals and timeline for emission pathways set in the Paris Agreement are relevant to determining what constitutes “necessary measures” to be taken under UNCLOS. In effect, then, the Paris Agreement can be thought of as setting the “floor” but not the “ceiling” for action. (4) The “necessary measures” any state is required to take under UNCLOS will depend, at least in part, on its scientific, technical, & financial capacity. Consistent with the CBDR principle, ITLOS suggests that more may be expected of developed States than developing ones. But the latter aren’t off the hook. According to ITLOS, “all States must make mitigation efforts.”
