There is plenty of water to go around and human beings are not using all that much. Every year, thousands of cubic kilometres (km3) of fresh water fall as rain or snow or come from melting ice. According to a study in 2007, most nations outside the Gulf were using a fifth or less of the water they receive—at least in 2000, the only year for which figures are available. The global average withdrawal of fresh water was 9% of the amount that flowed through the world’s hydrologic cycle. Both Latin America and Africa used less than 6% (see table). On this evidence, it would seem that all water problems are local. The trouble with this conclusion is that no one knows how much water people can safely use. It is certainly not 100% (the amount taken in Gulf states) because the rest of creation also has to live off the water. In many places the maximum may well be less than one fifth, the average for Asia as a whole. It depends on how water is returned to the system, how much is taken from underground aquifers, and so on. But there is some admittedly patchy evidence that, given current patterns of use and abuse, the amount now being withdrawn is moving dangerously close to the limit of safety—and in some places beyond it. 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...
It is not the absolute number of people that makes the biggest difference to water use but changing habits and diet. 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. Different foods require radically different amounts of water. 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)...
The Economist
There is plenty of water to go around and human beings are not using all that much. Every year, thousands of cubic kilometres (km3) of fresh water fall as rain or snow or come from melting ice. According to a study in 2007, most nations outside the Gulf were using a fifth or less of the water they receive—at least in 2000, the only year for which figures are available. The global average withdrawal of fresh water was 9% of the amount that flowed through the world’s hydrologic cycle. Both Latin America and Africa used less than 6% (see table). On this evidence, it would seem that all water problems are local. The trouble with this conclusion is that no one knows how much water people can safely use. It is certainly not 100% (the amount taken in Gulf states) because the rest of creation also has to live off the water. In many places the maximum may well be less than one fifth, the average for Asia as a whole. It depends on how water is returned to the system, how much is taken from underground aquifers, and so on. But there is some admittedly patchy evidence that, given current patterns of use and abuse, the amount now being withdrawn is moving dangerously close to the limit of safety—and in some places beyond it. 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...
It is not the absolute number of people that makes the biggest difference to water use but changing habits and diet. 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. Different foods require radically different amounts of water. 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)...The Economist
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