Reading Climate Change Treaties: The International Court and Historic Responsibility for Greenhouse Gas Emissions

The much-anticipated hearings in the Advisory Opinion on State obligations with respect to Climate Change concluded last December and the International Court is expected to give its judgment sometime this year. Of the many arguments presented, the question of responsibility for historic emissions loomed large. A bewildering array of possible interpretations of climate change treaties were presented by the parties. The areas of contestation mirrored the divisions between States frequently seen at the annual UN Climate Change Conferences, with the majority of industrialised developed States adopting an interpretation of the law that would effectively shield them from responsibility for historical greenhouse gas emissions. Yet the Court has been called upon to provide a way out of the current impasse by a decision rooted in legal instruments and the techniques and processes of legal decision making. In this lecture, I will interrogate the many possible readings of the Climate Change treaties and attempt to offer a pathway to a meaningful and effective decision.

Phoebe Okowa - Phoebe Okowa is Professor of Public International Law at Queen Mary University of London. In 2021, she was elected to the United Nations’ International Law Commission, becoming the first African woman to serve on the Commission since it was established in 1947. She has written extensively on general international law including the law of state responsibility, aspects of protection of the environment including protection of natural resources in conflict zones, the relationship between state responsibility and accountability for international crimes, and the application of international law by domestic courts. In 2026, she will deliver the Hague Academy lectures on accountability for colonial wrongs in international law. In addition to her purely academic work, she has undertaken extensive advisory work for governments and non-governmental organizations on questions of public international law including as counsel before the International Court of Justice and the International Tribunal for the Law of the Sea.

Okowa was born and educated in Kenya. After completing her Legum Baccalaureus (LL.B.) with first class honours at the University of Nairobi in 1987, Okowa won a Foreign and Commonwealth Office scholarship to Wadham College, University of Oxford, where she studied for the degree of Bachelor of Civil Law (BCL). She subsequently completed a doctorate in law (DPhil.) supervised by the Chichele Professor of International Law, the late Ian Brownlie. In 2024, she was conferred a Doctor of Laws (honoris Causa) by Stockholm University. She took her first academic appointment at the University of Bristol in 1993 before moving to Queen Mary, University of London. She has twice been Global Visiting Professor at NYU Law School (2011 and 2015) and was most recently visiting Professor at the Graduate Institute for International Studies in Geneva. Professor Okowa is the joint editor of the Oxford Monographs in Public International Law (with Roger O’Keefe). She was for many years a member of the executive committee of the International Society of Public Law (ICON-S) and sits on the advisory board of numerous academic journals and learned societies. .

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