This ground-breaking study addresses for the first time the links between European Union defence, energy and climate change, proposing a set of concrete recommendations to defence decision-makers on climate change mitigation and adaptation. The study explores the impacts of climate change on the European Union defence sector and armed forces, particularly via dependencies on critical energy infrastructure, their vulnerabilities, providing real-life examples to demonstrate current challenges and opportunities, and addresses emerging and future requirements for managing climate risk. European Union Ministries of Defence and relevant stakeholders are expected to gain important insights from this study that can be used to ensure sustainability and resilience of critical energy infrastructure. This study was produced in the context of the Consultation Forum for Sustainable Energy in the Defence and Security Sector to support the implementation of the European Union’s Climate Change and Defence Roadmap in the framework of the European Union’s Strategic Compass for Security and Defence.