4th Montréal Climate Security Summit

On October 8-9, 2025, the 4th Montreal Climate Security Summit brought together more than 280 high-level participants from across government, military, academia, civil society, and industry to exchange views on the growing security challenges posed by climate change and the cross-sectoral solutions needed to address them in a defence context.

Co-organized by the Conference of Defence Associations (CDA) Institute and the NATO Climate Change and Security Centre of Excellence (CCASCOE), the 2025 edition of the Summit focused on strengthening military adaptation in the face of increasingly complex and non-linear climate risks. Discussions featured a mix of plenary sessions, roundtable discussions, and interactive workshops encouraging active audience engagement.

This report captures the Summit’s key insights, highlighting climate change as a defining driver of instability and an operational challenge for modern defence planning. It aims to inform policy and operational decision-making by emphasizing the need for enhanced data-sharing, cross-sectoral collaboration, and forward-looking approaches to resilience across military domains and geographical regions such as the Arctic, Eastern Europe, and the Middle East and North Africa.

Summit recommendations converged on four priorities: integrating climate adaptation into defence procurement, planning and operations; strengthening decision-making through better integration of scientific and defence data; advancing whole-of-society resilience through risk-governance, investments and capacity-building; and treating defence decarbonization as a core security imperative.