Background

Background

Water is essential for energy systems, ecosystem services, and a wide range of life-sustaining and critical human activities. It is also a major component underlying a suite of important climate processes and feedbacks, including the biogeochemical cycles that impact carbon and nitrogen exchanges, aerosol and cloud formation, as well as water vapor and cloud feedbacks that affect regional and global climates. These are all major research thrusts currently within the Department of Energy’s climate research programs. In turn, these research thrusts can support improved predictive understanding of the water cycle as these various connected systems exhibit “mutual constraints” with water in all its phases.

Both observational and modeling studies have suggested an accelerated hydrological cycle in a warmer climate, with increasingly uneven distributions of water, both spatially and temporally, and more frequent extremes. The impacts on human and natural systems will be profound, particularly for energy production and use, land use, and ultimately, feedbacks to the climate system. Currently, more than 60% of non-consumptive water that draws from major U.S. rivers and streams is for energy production. In addition, an increasing amount of energy is now required to manage water resources; approximately 10% of California’s energy resources are dedicated to managing water right now!

As conditions change, regions of the country that have been largely immune from such issues will, under climate change, be confronted with similar challenges in what will be a dynamic regime for water resources. Ultimately, today’s scientific uncertainties in predicting long-term changes in global and regional hydrologic cycles, and implications for both surface and subsurface water supplies, fundamentally limit the United States' ability to develop sustainable energy solutions. That being said, predicting changes to the regional hydrologic cycle is a daunting scientific challenge. The water cycle is influenced by many processes such as clouds, precipitation, soil moisture, runoff, vegetation, subsurface phenomenon, weather and storm patterns, which evolve with the climate. In addition, water cycle predictions are inherently driven by multi-scale phenomena. Adding to these challenges are potential human activities related to energy, water, and land use that historically and with increasing complexity, leave ubiquitous footprints on the water cycle.

Modeling the fully integrated natural and human components of the water cycle is a significant scientific challenge that is well aligned with DOE’s mission needs and core competencies in integrative modeling, drawing from unique and highly relevant process research, including: regional and global climate modeling, integrated assessment modeling, Earth system modeling; cloud and aerosol research and modeling and atmospheric radiation measurement; terrestrial ecosystem research and modeling, including carbon cycle modeling; subsurface research and modeling; broader DOE multi-laboratory studies and modeling capabilities on the energy-water nexus and CESD research at the Energy-Water-Land Nexus including the recent DOE led National Climate Assessment study on this topic.