Law of the Sea, climate change and state responsibility

This paper examines the relevance of rules on state responsibility for environmental violations, and specifically those related to climate change, under Part XII of the United Nations Convention on the Law of the Sea (UNCLOS). The paper focuses on one central question: Can, and should, tribunals constituted under UNCLOS hold States accountable for climate-related environmental harm? To do so, it considers recent judicial developments, such as the International Tribunal for the Law of the Sea (ITLOS) Advisory Opinion on Climate Change, alongside UNCLOS provisions, other relevant legal instruments, and case law. The paper argues that, if a State can be shown to have failed to act diligently to address the risks of climate change and associated environmental damage, it could become vulnerable to litigation under UNCLOS. Such an omission may constitute a wrongful act under the doctrine of state responsibility, resulting in obligations of reparation. In some instances, this could include compensating for the costs of climate change-related harm. However, establishing a breach presupposes that a) injured, and possibly even non-injured, States are willing to pursue environmental claims under UNCLOS against non-compliant States and b) UNCLOS tribunals are prepared to scrutinise State parties' decisions and policies related to climate change. This scrutiny would involve assessing whether those national measures fulfil the due diligence requirement under Part XII of UNCLOS and whether they are adequate in light of the scientific evidence on environmental risks.