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The 21st century promises to confront humankind with a host of new resource and environmental challenges, virtually all driven by continued population growth. The most recent population forecasts envision growth continuing at least through the majority of the 21st century, and perhaps beyond, with an expected peak world population of 9-11 billion. For the most part, the additional 3-5 billion people will be added to the poorer and resource-limited regions of the world, creating enormous challenges in the management of scarce resources and in the production of adequate quantities of food and fiber.
In particular, the incremental stresses that these additional people will place in the world's water resources will sharply intensify the existing world water scarcity and lead to a host of critical water management challenges. Thus, for example, the task of feeding an enlarged population will almost surely require the expansion of irrigated acreage world-wide with attendant increases in the demand for water. Already there are signs that food production advances are being overtaken by population growth. Worldwatch reports that grain production failed to match consumption in 10 of the last 15 years between 1987-2001, causing grainstocks to decline to lower and lower levels. The latest UN analysis estimates that 25,000 people are starving to death each day, and as many as 800 million are undernourished. Food production clearly needs to increase sharply in the years ahead to prevent widespread famine and disease. And, such increases in food production will invariably be accompanied by increases in water demand.
Although substantial effort is being focused on development of higher-yielding crops, a growing number of experts believe that water availability will become a limiting factor in crop production, and that water shortages will become chronic in some of the most populous regions of the world. In fact, a significant portion of today's crop production capacity may be ephemeral, because it relies on temporary water availability. Postel (1994) has estimated that as many as 500 million people today are being fed by crops grown with water obtained by groundwater overdraft, the majority in China and India. UN estimates project that at least 3 and as many as 7 billion people will live in chronically water-short areas by the end of the century. And on top of this dire forecast looms the uncertainty of climate change, which by recent estimates could decrease river flow supply to certain populous areas by as much as 20%.
Even in the face of prospective increases in demand, water supplies are also being lost at a growing rate from pollution, especially in poor countries undergoing rapid industrialization and urbanization. Water pollution is already a major cause of death in the world today, from diarrheal diseases, malaria, and parasitic infections. It is estimated that 1 billion people worldwide today lack access to clean water. Twice that many are estimated to lack adequate sanitation facilities. Virtually all of these people dwell in areas where sharp population increases are expected.
As the world scrambles to meet ever-growing water demands, the likelihood is that ecosystems will suffer untold damages. More than 50% of the world's wetlands have been lost since 1900, and as many as 80 fish species have become extinct. Sixty percent of the world's 227 largest rivers are subject to serious flow disruption from dams, diversions, and canals, leading to degradation of downstream ecosystems. Every day, 2 million tons of human waste are disposed of in rivers and streams. Moreover, our understanding of aquatic ecosystems and their water requirements is rudimentary at best. The task of maintaining and enhancing water based environments while providing water for basic human needs and economic growth will be enormous.
No one disputes that there is adequate water in the world to meet the needs of humanity. The world's problems are caused largely by regional and temporal shortages, lack of technology, and poor management. Science will play a critical role in determining whether we will be successful in addressing the daunting array of water problems that beset the world. While new science will be necessary and helpful, there is also a need to employ existing scientific principles on a wide scale if we are to address the water resource problems of today and develop effective propose solutions that can be implemented globally in the coming decades.
William Jury, University of California, Riverside
Session I: Water Problems from a Global Perspective
Global Problems of Water Scarcity and Conflict
Malin Falkenmark, Stockholm International Water Institute
The Implications of Global Change for the World's Water Resources
Michael Dettinger, U.S. Geological Survey and Climate Research Division / Scripps Institute of Oceanography
Global Water Quality: Implications for Supply and Health
Pat Brezonik, University of Minnesota
Feeding a More Populous World
Alexander Zehnder, Board of the Swiss Federal Institutes of Technology
Session II: Water and the Environment
Evaluating the Importance of Aquatic Ecosystems
William Lewis, University of Colorado
Recent and Prospective Scientific Advances in Aquatic and Terrestrial Ecology
Barbara Bedford, Cornell University
Science for Water Development and Wildlife Preservation
Will Graf, University of South Carolina
The Increasing Importance of the Agricultural / Environmental Tradeoff in Managing Water Resources
Elias Fereres, University of Cordoba, Spanish Academy of Engineering
Session III: New Perspectives in Water Management
The Prospects and Problems of Storage
Alessandro Palmieri, World Bank
The Prospects for Emerging Water Technology
Rhodes Trussell, Trussell Technologies
Soft Path Technologies for the Developing World
Frank Rijsberman, International Water Management Institute
Groundwater Resource Management Challenges in North China
Richard Evans, Sinclair-Knight-Merz
Session IV: The Importance of Water Institutions
The Importance of Institutions and Policy in Resolving Global and Regional Water Scarcity
Helen Ingram, University of California, Irvine
The Role of International Law
Steve McCaffrey, University of the Pacific McGeorge School of Law
Henry Vaux, University of California, Berkeley