Introduction

The Introduction identifies the key developments in international environmental law and policy during the first three eras of international environmental governance and highlights the limitations in the significant body of international environmental law and policy agreed by states in addressing escalating environmental crises. Next, it proposes that urgent and transformative change is needed in the Post-2020 ‘fourth’ era, and the research proposes a way to make international law and policy more effective through adopting an interactive approach during the entire implementation process.