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Water scarcity looms.

Water scarcity is growing in urgency in many regions as population growth, climate change, pollution, lack of investment, and management failures restrict the amount of water available relative to demand. The Stockholm International Water Institute calculated in 2008 that 1.4 billion people live in "closed basins"--regions where existing water cannot meet the agricultural, industrial, municipal, and environmental needs of all. In 2007 the UN Food and Agriculture Organization (FAO) calculated that 1.2 billion people live in countries and regions that are water-scarce. FAO estimates that the number of water-scarce will rise to 1.8 billion by 2025.

Water scarcity can be physical or economic. Physical water scarcity exists wherever available water is insufficient to meet demand. Economic water scarcity occurs when water is available but inaccessible because of a lack of investment in water provision or poor management and regulation of water resources.

Signs of scarcity are plentiful. Several major rivers, including the Indus, Rio Grande, Colorado, Murray-Darling, and Yellow, no longer reach the sea year-round as a growing share of their waters is claimed for various uses. Water tables are falling as groundwater is overpumped in South Asia, northern China, the Middle East, North Africa, and the southwestern United States, often propping up food production unsustainably The World Bank estimates that some 15 percent of India's food, for example, is produced using water from nonrenewable aquifers. Another sign of scarcity is that desalination, a limited and expensive water supply solution, is on the rise.

Population growth is a major driver of scarcity at the regional and global levels. Locally, pollution reduces the amount of usable water available to farmers, industry, and cities. The World Bank and the government of China have estimated, for instance, that 54 percent of the water in seven main rivers in China is unusable because of pollution. In addition, urbanization and rising incomes tend to increase domestic and industrial demand for water.

In some cases, water scarcity leads to greater dependence on foreign sources of water as shown by countries' "water footprints"--the volume of water used to produce the goods and services, including imports, that people consume. The ratio between the water footprint of a country's imports and its total water footprint yields its water import dependence (see table).
Water Import Dependence, Selected Countries, 1997-2001

Country         Water Import Dependence


Netherlands             82
Jordan                  73
United Kingdom          70
Japan                   64
South Korea             62
Germany                 53
Italy                   51
France                  37
Spain                   36
Mexico                  30
South Africa            22
Canada                  20
Egypt                   19
United States           19
Australia               18
Russia                  16
Indonesia               10
Brazil                   8
Thailand                 8
China                    7
Argentina                6
Pakistan                 5
Bangladesh               3
India                    2

Note: Water import dependence is the ration of a country's external
water footprint to its total water footprint.

Source: Chapagain and Hoekstra, Water International, March 2008.

Climate change is expected to worsen water scarcity globally. By the 2050s, the area subject to greater water stress due to climate change will be twice as large as the area undergoing decreased water stress. Less rainfall is expected in already arid areas, including the Mediterranean Basin, western United States, southern Africa, and northeastern Brazil. Loss of snowpack will remove a natural, off-season water reservoir in many regions: by the 2020s, for example, 41 percent of the water supply to the populous southern California region is likely to be vulnerable to warming as some of the Sierra Nevada and Colorado River basin snowpacks disappear.

Policymakers look to a variety of solutions to address water scarcity. Desalination is increasingly feasible for small-scale water supply, as technological advances reduce costs. Global desalination capacity doubled between 1995 and 2006 and by some forecasts could double again by 2016. But production is tiny: Global capacity in 2005 was some 55.4 million cubic meters, barely 0.003 percent of the world's municipal and industrial water consumption. Forty-seven percent of global capacity in 2006 was in the Middle East, where the need is great and energy is cheap.

Other solutions focus on structural shifts in water use, including growing crops that are less water-intensive, changing dietary patterns to reduce meat consumption, and shifting to renewable sources of energy. Diets heavy in livestock products, for example, are water-intensive because of the huge quantities of water required for livestock production. Similarly, fossil fuel production requires many times more water than renewable energy sources do.

Vital Signs are adapted from Vital Signs Online, which contain additional data and more in-depth analyses.

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Title Annotation:VITAL SIGNS
Author:Gardner, Gary
Publication:World Watch
Geographic Code:1USA
Date:May 1, 2010
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