http://www.economist.com/displayStory.c ... d=13447271
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).
So the shift from vegetarian diets to meaty ones—which contributed to the food-price rise of 2007-08—has big implications for water, too. In 1985 Chinese people ate, on average, 20kg of meat; this year, they will eat around 50kg. This difference translates into 390km3 (1km3 is 1 trillion litres) of water—almost as much as total water use in Europe.
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.
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. This is a bigger population fall than that suffered by animals in jungles, temperate forests, savannahs and any other large ecosystem. Half the world’s wetlands, on one estimate, were drained, damaged or destroyed in the 20th century, mainly because, as the volume of fresh water in rivers falls, salt water invades the delta, changing the balance between fresh and salt water. On this evidence, there may be systemic water problems, as well as local disruptions.
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 (see second chart). In some countries, you need 1,500 litres of water to produce a kilo of wheat; in others, only 750 litres. It does not necessarily follow that water is being used unsustainably in the one place and not the other; perhaps the high-usage places have plenty of water to spare. But it does suggest that better management could reduce the amount of water used in farming, and that the world could be better off if farmers did so. 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.
Few people yet recognize that the upfront costs of Solar powered, LED-lit, Hydroponic Indoor Agriculture and Aquaculture will very soon be affordable as an investment for growing many crops. As the costs of both solar power and LED lights continue to drop below parity with grid electricity and the incandescent bulb, and cereal crops and growth conditions are optimized for it, solar-powered, LED-lit Hydroponics Indoor Agro will be the most viable means of growing all types of food.
This will not just be the purview of Vancouver, Berkeley and Amsterdam pot growers who have based a $20 Billion/year industry on this technology.
Already in British Columbia, Canada, 99% of all tomatoes, cucumbers and peppers eaten in the province are grown in greenhouses using hydroponics.
And here’s a reminder about a development from last year:
Welcome to Thanet Earth: The biggest [Hydroponics] greenhouse in Britain unveiled
http://www.dailymail.co.uk/sciencetech/ ... eiled.html
The scale of the £80 million project is mind-boggling. When complete, its seven greenhouses will sprawl across 220 acres of Kent countryside [1/3 of a square mile], occupying the same area as six London Zoos.
Each greenhouse will be 1,240ft long, centrally heated and fed by its own private reservoir.
Conditions will be monitored and controlled by computers. Plants will be grown year round, suspended in vast rows from the 26ft-high ceiling.
A staggering 2.5 million tomatoes will be cropped every week of the year; 560,000 peppers and 700,000 cucumbers will be picked weekly during a shorter season between February and October.
This massive harvest will boost Britain's salad crop production by 15 per cent - reducing reliance on imports.
To enable production on this industrial scale, the science of hydroponics is utilised.
Similar techniques were used to create the ancient Hanging Gardens of Babylon and the floating gardens of the Aztecs in Mexico.
Let’s have some fun doing Global Hydroponics Algebra to figure out what would it take to feed the whole world its salad vegetables through this method.
If 220 Acres of hydroponics = 15% (~1/7th) of UK salad vegetable consumption
7 X 220 Acres = 1540 Acres = 100% of UK salad veggie consumption
UK population is 61 Million
World population is 6.7 Billion
World is 110 X larger than UK
So 1540 Acres X 110 =
170,000 Acres is needed to feed the entire planet’s population their salad vegetables at a similar quantity as a Brit.
Since 640 Acres = 1 square mile,
170,000 / 640 = 264 Square Miles
New York City (Bronx, Brooklyn, Manhattan, Queens, & Staten Island) = at 305 Square miles.
NYC is larger than what the planet needs for its veggies
The entire planet can be fed fresh salad veggies at the level of consumption of the Brits by covering an area smaller than the size of New York City with a one story hydroponics greenhouse.
By 2012, when they are cheap enough:
Since Solar Panels gather 10X as much light energy as plant growth-tuned, red and blue LEDs put out, a 10-story Solar, LED, Hydoponics requires the land area of only Manhattan itself (and not the other boroughs) to feed the entire planet’s population their salad veggies.