Impacts on the Terrestrial Water Cycle from Climate Change of Precipitation Magnitude, Pattern, Timing, and Intensity

Introduction The climate is a complex system that encompasses numerous Earth surface systems, i.e. the atmosphere, hydrosphere, cryosphere, lithosphere, and biosphere. The preponderance of scientific evidence indicates that anthropogenic actions such as excess generation of greenhouse gases are causing serious climatic change. Water is a critical resource to humans, commerce, wildlife, and the environment. This resource is already over-used and stressed in much of the United States and the world. A thorough understanding of the relationships between climate change and water resources could help improve the construction and evaluation of accurate climate models. Changes of many of the atmospheric climate elements, such as temperature, radiation, wind speed and direction, humidity, and precipitation can impact water resources (UN IPCC, 2007). Precipitation is the most critical element for water impacts. It is typically characterized and measured mainly in terms of total annual precipitation. However, precipitation can be further classified by other characteristics such as the intensity of precipitation events, duration of events, frequency of precipitation events, and recovery time between events The terrestrial hydrologic cycle is that portion of the global hydrologic cycle that takes place on the land surface and sub-surface. It is a complex system with many transport and storage Each precipitation characteristic can influence how water partitions among the various hydrologic cycle components. In fact, changes of each precipitation characteristic could produce a quantitatively different impact on each of these components. Rationale This proposed research is concerned with the connections and impact of climate change on water resources. This work is motivated by statements such from the Stockholm International Water Institute and the World Wildlife Fund in late 2009 that " Water is the primary way that climate change will impact people, society and ecosystems. " which echoes the UN-Water in early 2009 that " Water is the primary medium through which climate change influences the Earth's ecosystems and therefore people's livelihoods and well-being " (UN-Water, 2009). Given the existing deficiencies in water availability and quality, further impacts from climate change could be especially challenging. Precipitation is not modeled in Global Climate Models (GCMs) with nearly the same accuracy or confidence as has been achieved with temperature projections. In fact, a current Nature report identifies precipitation as one of the fundamental gaps in current climate change research and that IPCC models " offer wildly diverging pictures " of precipitation (Schiermeier, 2010). The same problem is also true of regional …