Water Scarcity Looms

Worldwatch Institute
by Gary Gardner/ August 6, 2009

Water scarcity grows 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.1 Their estimate is consistent with a 2007 Food and Agriculture Organization (FAO) calculation that 1.2 billion people live in countries and regions that are water-scarce.2 And the situation is projected to worsen rapidly: FAO estimates that the number of water-scarce will rise to 1.8 billion by 2025, particularly as population growth pushes many countries and regions into the scarcity column.3

"Water scarcity" has several meanings. Physical water scarcity exists wherever available water is insufficient to meet demand: parts of the southwestern United States, northern Mexico, North Africa, the Middle East, Central Asia, northern China, and southeastern Australia are characterized by physical water scarcity.4 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. Much of the water scarcity of sub-Saharan Africa falls into this category. 5

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 are claimed for various uses.6 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.7 The World Bank estimates that some 15 percent of India's food, for example, is produced using water from nonrenewable aquifers.8 Another sign of scarcity is that desalination, a limited and expensive water supply solution, is on the rise.

Water scarcity has many causes. Population growth is a major driver at the regional and global levels, but other factors play a large role 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.9 In addition, urbanization tends to increase domestic and industrial demand for water, as does rising incomes-two trends prominent in rapidly developing countries such as China, India, and Brazil.10

In some cases, water scarcity leads to greater dependence on foreign sources of water. A country's "water footprint"-the volume of water used to produce the goods and services, including imports, that people consume-can be used to demonstrate this.11 The ratio between the water footprint of a country's imports and its total water footprint yields its water import dependence. The higher the ratio, the more a country depends on outside water resources. In the Netherlands, for example, imported goods and services account for 82 percent of the country's total water footprint.12 (See Table 1.)

A looming new threat to water supplies is climate change, which is causing rainfall patterns to shift, ice stocks to melt, and soil moisture content and runoff to change.13 According to the Intergovernmental Panel on Climate Change, the area of our planet classified as "very dry" has more than doubled since the 1970s, and the volume of glaciers in many regions and snow pack in northern hemisphere mountains-two important freshwater sources-has decreased significantly.14

Climate change is expected to have a net negative impact on water scarcity globally this century. By the 2050s, the area subject to greater water stress due to climate change will be twice as large as the area experiencing decreased water stress.15 Less rainfall is expected in already arid areas, including the Mediterranean Basin, western United States, southern Africa, and northeastern Brazil, where various models all indicate that runoff will decrease by 10-30 percent in the coming decades.16 And 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.17

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. This involves removing most salt from salt water, typically by passing it through a series of membranes. Global desalination capacity doubled between 1995 and 2006, and according to some business forecasts it could double again by 2016.18 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, largely because desalination remains an energy-intensive and expensive option.19 Not surprisingly, 47 percent of global capacity in 2006 was in the Middle East, where the need is great and energy is cheap.20 In addition, the technology is plagued by environmental concerns, especially disposal of salt concentrates.

Another limited solution to scarcity involves accounting for "virtual water"-the water used to produce a crop or product-when designing trade policy. Nations conserve their own water if they import products having a large virtual water component, such as foodstuffs, rather than producing them domestically. Imports to Jordan, for instance, including wheat and rice from the United States, have a virtual water content of some 5-7 billion cubic meters per year compared with domestic water use of some 1 billion cubic meters per year.21 Jordan's import policy yields enormous water savings for the country, although it also increases its food dependency. The bulk of North and South America, Australia, Asia, and Central Africa are net exporters of virtual water.22 Most of Europe, Japan, North and South Africa, the Middle East, Mexico, and Indonesia, in contrast, are net importers of virtual water.23

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.24 (See Table 2.) Similarly, fossil fuel production requires many times more water than renewable energy sources do. 25 (See Table 3.)

Complete trends will be available with full endnote referencing, Excel spreadsheets, and customizable presentation-ready charts as part of our new subscription service, Vital Signs Online, slated to launch this fall.

http://www.worldwatch.org/node/6213?emc=el&m=279787&l=4&v=7c1e33b23a