This topical Handbook explores the emergence of climate change as an international security issue, the threats it poses, and the political and academic debates it has prompted. Framing climate change as a security issue, it explores the ways relevant actors, states and international organizations have conceptualized climate security and its associated threats. Theoretically sound and empirically innovative, this Handbook explores the political implications of linking climate change and security and tackles the questions that are subsequently raised. Through a collection of international case studies, expert contributors explore a diverse range of issues emerging in the debate about climate change and security, including the problem of migration, the impact on energy security and the role of the military. Contributing to various discourses, logics, practices and constructions of climate security, the Handbook outlines how security language shapes and transforms the way climate change is governed. Ultimately, it identifies an emerging, broader reconceptualization of international security in the Anthropocene. Displaying the challenges that climate change poses in the context of existing security practices and institutions, this Handbook will be vital for policymakers looking to identify and understand threats to formulate effective countermeasures. It will also prove useful to students and scholars of security studies, international relations, climate change and energy politics, environmental politics and policy, and governance.