This chapter examines the literature on the potential security consequences of climate change. In particular, this chapter outlines two critical aspects of climate security: the role of the Arctic and the trans-boundary and international nature of climate change (and associated impacts). Finally, this chapter also considers the extensive literature that has attempted to model the linkage between climate change and security through empirical approaches. I find that the academic literature reveals important misalignments when considering climate security with respect to NATO. Firstly, the research evaluated is based upon historical data that is unlikely to reflect the future environment under conditions of unprecedented climate change. Secondly, the research insufficiently accounts for the globally (or trans-boundary) cascading consequences that may arise from climate variation in other regions. Thirdly, the various definitions of security used in the literature do not correspond to the definition used by NATO.