Predicted climate change over the coming decades is likely to add measurable stress to water resources in many regions of the world, including some areas that are currently well endowed. The stresses are likely to involve changes in the frequency of extreme events as well as gradual changes in mean annual net resources. The paper analyses these predictions. It also attempts to place them in context, first, comparing their impact with other major barriers to sustainability, such as increasing demand, wastage, poor water resources assessment and international conflict, and, secondly, considering the limitations of current predictive techniques.