This chapter examines the ICJ’s influence on international environmental law. Drawing on concrete examples, the author identifies six ways in which the Court’s jurisprudence has contributed to environmental law: by articulating foundational principles; by acting as a gatekeeper for customary international law; by elaborating existing principles; by interpreting environmental agreements; by valuing environmental harms; and by incorporating environmental considerations into other areas of international law. The author reflects on potential future evolutions of the Court’s role in the international environmental law space, given the increasing number of disputes that the Court has addressed in this field in recent years.

Adoption is the formal act by which the form and content of a treaty are settled. The classic principle was that, unless otherwise agreed, adoption needed the consent of all the states participating in drawing up the text. But often, in the case of a multilateral treaty drawn up at an international conference, a text is adopted by a specified majority, although consensus will normally be sought. Adoption of a bilateral treaty text is normally achieved by initialling. The process of establishing the final text is known as authentication and consists of a formal indication that a document contains the authentic and definitive text. Treaties adopted within an international organisation will follow that organisation’s rules. Sometimes, a diplomatic conference will conclude with a summary of proceedings known as a ‘final act’, to which a treaty adopted by that conference will be annexed. ‘Conclusion’ of a treaty is not defined in the Vienna Convention on the Law of Treaties but normally refers, in the case of a bilateral treaty, to signature of that treaty, and, in the case of a multilateral treaty, either to signature of the final act or the date on which the treaty is opened for signature.

How do we perceive the rest of nature meaningfully from the vantage point of our manufactured spaces? Whether the life teeming in a tropical forest, or surviving tenaciously on the remote reaches of the planet, we impact life that we probably never see first-hand. Our impact is from the manifestation of our nature, which is creative, industrious and prolific. Unfortunately, our impact threatens the stability of the only biosphere we can call home. How can human nature be connected to instead of orphaned from the rest of nature? No matter how much data we acquire about the crises we create for ecosystems, there remains tremendous inertia to apply the principal remedy: changing our behaviour. This implies the necessity to expand our focus from quantitative deduction of the problem and solutions, to ensuring we have the inner connections and relationships necessary for qualitative response to environmental stress. Does art create this sensitive bridge?

The first twenty years of international negotiation on climate change took an approach that was guaranteed to fail: attempting to solve an immensely complex issue through a single, legally binding agreement. The history of diplomacy in trade and security shows that success requires a different approach: breaking a problem up into manageable parts, and growing agreement gradually, strengthening it as parties’ interests increasingly converge.

Important parts of the Earth’s climate and environment can change in ways that are self-reinforcing, sudden, and irreversible. The risks of such changes are under-researched, under-reported in what is communicated by scientists to governments, and underestimated. In the most authoritative science assessments, the most important policy question of all – whether the climate will be stable at low degrees of warming – is hardly even raised.

When a new state comes into being, it is important to know which treaties, bilateral or multilateral, applied to it when it was part of another state, and which still apply to it. The Vienna Convention on Succession of States in Respect of Treaties 1978 seeks to regulate the issue, but only twenty-three states were parties by July 2022. Certain customary law principles, which the chapter outlines, can, however, be stated with reasonable confidence. The chapter also examines the case of former colonies and other overseas territories, and the approaches known as universal succession and the clean slate doctrine. It takes a detailed look at the two German states, the former Soviet Union, the former Yugoslav Republics, the former Czechoslovakia, and Hong Kong and Macau. It also discusses the role of the depositary in cases of treaty succession.

The Vienna Convention on the Law of Treaties 1969 contains the body of rules governing the law of treaties. Its scope covers treaties between states. The rules largely reflect customary international law. So even where states are not parties to the Convention, its rules will often apply to their treaty relations by virtue of customary international law. Treaties between a state and an international organisation, or between international organisations, are not covered by the 1969 Convention. But international organisations may be party to the separate Vienna Convention of 1986, which adapts the rules of the 1969 Convention to international organisations. If they are not parties to the 1986 Convention, customary international law will apply to their treaty relations. The 1969 Convention does not cover oral agreements, which are in any case extremely rare. The 1969 Convention does not have retrospective effect. The implications of this are discussed.

Neither scientists, nor economists, nor insurers, nor military planners have assessed the risks of climate change in full. Heads of government are left to guess. A clear understanding of the scale of the risks will not on its own guarantee a proportionate response. But unless we have such an understanding, we can hardly be surprised if our response is inadequate.