Climate change represents one of the most significant challenges to global water security and sustainable development. Variations in precipitation patterns, accelerated glacial melts, rising sea levels, and the increasing frequency of extreme weather events have destabilized hydrological systems worldwide. Population growth and rapid urbanization have further intensified water demand and resource depletion. Using visual and geospatial data from platforms such as National Geographic and Our World in Data, this entry examines the sustainability of global water resources in a changing climate. It explores the mechanisms linking climate change and water security through a systems perspective, emphasizing global interconnections, adaptation strategies, and policy frameworks shaping water resilience across regions.