Climate change has and will continue to have both direct and indirect effects around the world. Changes in water will be one of the most visible direct effects, whether it is too little water, such as during prolonged droughts; too much, such as flooding caused by sea-level rise or tropical storms; or misaligned timing, such as when seasonal rains are early or late. Across numerous societies, the climate change-water interaction will be disruptive, but through mitigation and adaptation actions, this interaction can at least be ameliorated. However, these disruptions will also have significant security implications locally, regionally, and globally depending on their intensity, spatial extent, and longevity, and due to their disproportionate effects on different segments of societies. This deteriorating security environment is very likely to increase the vulnerability of affected populations, enhance inequities, and interfere with mitigation and adaptation actions, which will prolong instability. Thus, any security analysis must integrate the effects of climate change on water, and its attendant effects on the vulnerability of populations, to capture a true picture of the security environment. Resources like the newly-released World Water Development Report (WWDR), titled “Water and Climate Change,” should therefore be taken very seriously by the security community.