Both are important. Adaptation to climate change will help manage the effects of climate change on security that are unavoidable. Mitigating climate change will help avoid future climate change scenarios that will make it difficult for governments and societies to manage the attendant security risks. The key is risk management.

Read more:

2014: “National Security and the Accelerating Risks of Climate Change,” CNA Corporation
2013: Thirty-Eight Leading U.S. National Security Experts Urge Action on International Climate Change Initiatives. Partnership for a Secure America
2013: Underpinning the MENA Democratic Transition: Delivering Climate, Energy and Resource Security. E3G
2013: Planning for Complex Risks: Environmental Change, Energy Security and the Minerva Initiative. Briggs, Chad.
2013: Understanding Climate Diplomacy: Building diplomatic capacity and systems to avoid dangerous climate change. Mabey, N. Gallager, B, Born, C. E3G
2012: Protecting Americans in the 21st Century: Communicating Priorities for 2012 and Beyond. National Homeland Security Consortium.
2011: Degrees of Risk: Defining a Risk Management Framework for Climate Security. Mabey, N. et al. E3G
2010: Climate Conflict: how global warming threatens security and what to do about it. Mazo, J., London: International Institute for Strategic Studies (IISS)
2010: Climate Security: Impacts and Opportunities for Transatlantic Relations. Feakin, T. and Depledge, D. Washington, DC: GMF.
2010: Future Landscapes of Conflict or Cooperation? Climate Security Needs Transatlantic Leadership. Taenzler, D. and Carius, A. Washington, DC: GMF.
2007: Meeting the Climate-Change Challenge Avoiding the Unmanageable & Managing the Unavoidable. John P. Holdren. Roundtable on Air Pollution/Atmosphere & Climate Change. United Nations Commission on Sustainable Development