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Fresh Water: Our Earth Community's Survival Depends Upon ItGlobal Abundance, Local ScarcityFresh water is one of the earth's most precious resources. While there is plenty of water to meet human need, it is often distributed unevenly. Fresh water comprises about 2.5 percent of the world’s total volume of water. Most of that amount is in the form of ice or snow and lies deep in underground aquifers or is in remote locations. Less than one percent of the world’s freshwater is readily available for human use. i Freshwater stores are continually being replenished through the hydrologic cycle, a continuous cycling of water from the earth’s oceans to land through evaporation, condensation, precipitation as rain, sleet or snow, and back to the ocean again through runoff. Most of the water that does not runoff quickly seeps into the ground to recharge aquifers. Good water management plays a vital role in realizing the abundance of the earth’s freshwater supply. For instance, two countries that experience the highest levels of water scarcity, Israel and Jordan, also have water supplies adequate to meet their people’s need — due, in part, to an efficient irrigation system. ii Global Supplies: A Management IssueOveruse and water quality issues continually threaten existing freshwater supplies. The United Nations Environmental Program reports, “Freshwater consumption increased sixfold between 1900 and 1995 — at more than twice the rate of population growth.” Furthermore, within the next 25 years, two-thirds of the world’s population will live in water-stressed or water-scarce communities if present rates of consumption continue. Already 14 African countries face water-stressed conditions, with another projected 11 countries added to the count within the next 25 years. iii Agriculture and industry claim the highest rates of use of freshwater resources. Globally, about 70 percent of freshwater consumption is used for agriculture. The highest rates of agricultural use occur in Asia and Africa. North America and Europe use more water for industry than for agriculture. Overall, if trends continue, water use is expected to increase by 40 percent over the next 25 years, with 17 percent more going for agricultural use and another 20 percent for industry. Groundwater resources are used by about one-third of the world’s people. Excess withdrawals, withdrawals of ground water at a rate greater than can be naturally recharged, are occurring in parts of the Arabian Peninsula, China, India, Mexico, the former Soviet Union and the United States. In parts of the world, overuse of groundwater resources threaten water supply systems that have been used for thousands of years. Excess withdrawal of groundwater also increases the risk of land subsidence and saltwater intrusion. California’s San Joaquin Valley has sunk by eight meters since the 1920s, a clear example of the secondary effects of excess water withdrawals. iv In addition to overuse, urbanization threatens groundwater recharge rates. By estimating the increase in impervious surfaces in 20 of the fastest growing metropolitan areas in the US between 1982 and 1997, the Natural Resources Defense Council (NRDC) has concluded that Atlanta, GA, may have lost between 56.9 billion to 132.8 billion gallons of water to excess runoff, an amount that could have supplied the household needs of 1.5 million to 3.6 million people. v Human-induced climate change also presents a concern for water managers, as erratic weather increases the likelihood that both floods and droughts will contribute to the problem of water scarcity. Worldwide, one-in-five persons lack access to safe drinking water and one-half lacks adequate sanitation. Sewage, the world’s largest pollution problem, affects both surfacewater and groundwater supplies. Annually, water pollution affects the health of about 1.2 billion people and contributes to the deaths of 15 million children under age five. vi As industrial and agricultural use increases, so will the risk of pollution. Industrial pollutant emissions are expected to increase fourfold over the next 25 years. Agricultural uses of pesticides and fertilizers have a deleterious effect on the earth’s water stores. Nitrates from fertilizer are one of the most serious water pollution problems, affecting both human and ecosystem health. Excess nitrates in water systems lead to brain damage and even death in some infants. In the United States more than 40 million people take their drinking water from systems that exceed health-based standards. In Africa, nitrates in some groundwater supplies are six to eight times higher than World Health Organization standards. In the natural world, excess nitrates stimulate excess algae growth, leading to the death of waterways, like the dead zone that develops in the Gulf of Mexico. vii For more resources on fresh water from the United Nations visit http://www.unesco.org/water/iyfw. Footnotes Return to Earth Day 2003 Index
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