Water Resources and Climate Change

Abstract

Natural and human-caused climate changes are strongly linked to the hydrologic cycle and freshwater resources. The hydrological cycle is a core part of climate dynamics involving all three common forms of water—ice, liquid, vapor—and the movement of water around the world. Changes in climate affect all aspects of the hydrologic cycle itself through alterations in temperature, precipitation patterns, storm frequency and intensity, snow and ice dynamics, the stocks and flows of water on land, and connections between sea levels and coastal wetlands and ecosystems. In addition, many of the social, economic, and political impacts of climate change are expected to be felt through changes in natural water resources and developed water systems and infrastructure. Extensive research extending back a century or more has been conducted around the world on all the subsection categories presented below. Despite many remaining uncertainties, major advances in basic scientific understanding of the complex processes surrounding freshwater and climate have been made in the past decadet. New ground- and space-based sensors collect far more water- and climate-related data in the 21st century than in the past. Improvements in both regional and global hydrological and climatological modeling have permitted far greater understanding of water and climate links and risks. And more water management institutions and managers are beginning to integrate information about past and future climatic variability into water system planning, design, and construction. Recent observational evidence indicates that the impacts of human-caused climatic changes can now be observed in some regions for a wide range of water resources, including changing evaporative demand associated with rising temperatures, dramatic changes in snow and ice, alterations in precipitation patterns and storm, rising sea levels, and effects on aquatic ecosystems.