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31 Oct 09

100 Incredible Open Courses for the Ultimate Tech Geek - Online Courses

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22 Apr 09

70+ Online Language Communities and Resources

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15 Apr 09

Water shortages go global | Sin aqua non | The Economist

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water resources world economics politics

THE overthrow of Madagascar’s president in mid-March was partly caused by water problems—in South Korea. Worried by the difficulties of increasing food supplies in its water-stressed homeland, Daewoo, a South Korean conglomerate, signed a deal to lease no less than half Madagascar’s arable land to grow grain for South Koreans. Widespread anger at the terms of the deal (the island’s people would have received practically nothing) contributed to the president’s unpopularity. One of the new leader’s first acts was to scrap the agreement.
An alarming number of the world’s great rivers no longer reach the sea. They include the Indus, Rio Grande, Colorado, Murray-Darling and Yellow rivers. These are the arteries of the world’s main grain-growing areas.
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- Freshwater fish populations are in precipitous decline. According to the World Wide Fund for Nature, fish stocks in lakes and rivers have fallen roughly 30% since 1970.
- Diet matters more than any single factor because agriculture is the modern Agasthya, the mythical Indian giant who drank the seas dry. Farmers use about three-quarters of the world’s water; industry uses less than a fifth and domestic or municipal use accounts for a mere tenth.
- To grow a kilogram of wheat requires around 1,000 litres. But it takes as much as 15,000 litres of water to produce a kilo of beef. The meaty diet of Americans and Europeans requires around 5,000 litres of water a day to produce. The vegetarian diets of Africa and Asia use about 2,000 litres a day (for comparison, Westerners use just 100-250 litres a day in drinking and washing).
- So the shift from vegetarian diets to meaty ones—which contributed to the food-price rise of 2007-08—has big implications for water
- The shift of diet will be impossible to reverse since it is a product of rising wealth and urbanisation. In general, “water intensity” in food increases fastest as people begin to climb out of poverty, because that is when they start eating more meat. So if living standards in the poorest countries start to rise again, water use is likely to soar.
- Moreover, almost all the 2 billion people who will be added to the world’s population between now and 2030 are going to be third-world city dwellers—and city people use more water than rural folk. The Food and Agriculture Organisation reckons that, without changes in efficiency, the world will need as much as 60% more water for agriculture to feed those 2 billion extra mouths. That is roughly 1,500km³ of the stuff—as much as is currently used for all purposes in the world outside Asia.
- The other long-term trend affecting water is climate change. There is growing evidence that global warming is speeding up the hydrologic cycle—that is, the rate at which water evaporates and falls again as rain or snow. This higher rate seems to make wet regions more sodden, and arid ones drier. It brings longer droughts between more intense periods of rain.
- Climate change has three big implications for water use. First, it changes the way plants grow. Trees, for example, react to downpours with a spurt of growth. During the longer droughts that follow, the extra biomass then dries up so that if lightning strikes, forests burn more spectacularly. Similarly crops grow too fast, then wilt.
- Larger floods overwhelm existing controls. Reservoirs do not store enough to get people or plants through longer droughts. In addition, global warming melts glaciers and causes snow to fall as rain. Since snow and ice are natural regulators, storing water in winter and releasing it in summer, countries are swinging more violently between flood and drought. That is one big reason why dams, once a dirty word in development, have been making a comeback, especially in African countries with plenty of water but no storage capacity.
- Second, climate change increases problems of water management.
- Third, climate change has persuaded western governments to subsidise biofuels, which could prove as big a disaster for water as they already have been for food.
- n short, more water will be needed to feed and heat a world that is already showing signs of using too much. How to square that circle?
- Still, industry consumes less than a fifth of the world’s water and the big question is how to get farmers, who use 70-80%, to follow suit. It takes at least three times as much water to grow maize in India, for example, as it does in America or China
- Changing irrigation practices can improve water efficiency by 30%, says Chandra Madramootoo, of the International Commission on Irrigation and Drainage. One can, for example, ensure water evaporates from the leaves of the plant, rather than from the soil. Or one can genetically modify crops so they stop growing when water runs dry, but do not die—they simply resume growth later when the rains return.
- The world might also be better off, at least in terms of water, if trade patterns more closely reflected the amount of water embedded in traded goods (a concept called “virtual water” invented by Tony Allan of King’s College London). Some benign effects happen already: Mexico imports cereals from America which use 7 billion cubic metres (m³) of water. If it grew these cereals itself, it would use 16 billion m³, so trade “saves” 9 billion m³ of water. But such beneficial exchanges occur more by chance than design.
- Big drinks companies such as Coca Cola have set themselves targets to reduce the amount of water they use in making their products (in Coke’s case, by 20% by 2012). The Nature Conservancy, an ecologically-minded NGO, is working on a certification plan which aims to give companies and businesses seals of approval (a bit like the Fairtrade symbol) according to how efficiently they use water.