This note is assigned in Darden's course elective, "Global Economics of Water." There is more than enough fresh water to satisfy the world's needs. The primary concern, however, is the geographical mismatch between water needs and the availability of water to communities who need it. Hence, a major challenge for the 21st century is to better manage this mismatch. In this note, we focus on one particular factor?climate change?and how it may contribute to future stress on water resources. We lay out the basics of climate change and the hydrological cycle, and we point to some of the intricate ways in which both phenomena are connected. This note does not contain blanket policy recommendations as to how to fight global warming beyond the general statement that the rational response to the risk and uncertainty of higher global temperatures and their associated environmental changes is to take actions that ensure against potentially adverse effects.