Looks like Greenpeace and Prince Charles are dead wrong. Some brainy people finally did the math.
Note, soil loss is one of the largest problems for the next 20 years. No-till farming, using herbicide is the best way to save soil.
The Guardian (UK)
03 June 1999
Will The World Starve Itself To Death?
Ban genetically modified crops is the war cry in Europe. Tim Radford on the bleak arithmetic which points to a bigger problem of famine.
In the time it takes to read this sentence, the world population will have grown by about five. There will be another 170 people in the world at the end of the next minute. This is because more babies are being born, and fewer old people dying each year.
There are about 240,000 more people in the world today than there were yesterday. The planet’s population grows by about 87 million every year. A science watchdog, the Nuffield Council on Bioethics, last week warned that there was a “moral imperative” to develop genetically-modified crops - higher-yielding, better-nourishing, more resistant - to feed the extra three billion mouths expected in the next three decades.
Never mind the council’s hotly-contested solution, just consider the problem. There are three needs for a harvest: acreage, fertile topsoil - that magic mix of decayed vegetation, rock dust and microorganisms formed at the rate of an inch or so a century - and fresh water. The consensus is that it takes 1.25 acres to provide a sufficient and varied diet for an adult human. Right now, the world average per person is just over two thirds of an acre.
For a while during the so-called Green Revolution food production outpaced population. Yields per acre grew, and the areas under cultivation increased. But the area of harvested cropland reached its peak in 1981, and has been falling ever since: for two reasons. One is that with more people, there is more demand for somewhere to live, which consumes farmland. The other is that farmland is being destroyed by being overworked. The area of grain cropland per person on the planet has shrunk to a sixth of a football field.
The minimum grain diet to keep a vegetarian supplied with bread, rice or cornmeal porridge for a year is 490kg. How much grain you can grow upon a sixth of a football field depends on sunlight, soil and water. The depth of topsoil is critical. The latest estimate, from David Pimentel of Cornell University, New York state, is that farmers are losing 24 billion tons of topsoil every year to wind and water erosion. At this rate, one third of the world’s arable land will be depleted within the next 20 years.
In the last 40 years, under pressure to feed much smaller populations, farmers have already abandoned an area equivalent to one third of the present harvest lands. So every year, they walk off 25 million acres of once productive land. But every year, 12 million acres of new land have to be found to feed the 90 million or so new mouths which arrived that year. Most of the world’s unfarmed land is either too wet, too dry, too steep or too cold for agriculture, which is why tropical and temperate forests are being cleared at a devastating rate.
The word devastating is appropriate: the forests are home to millions of as-yet undescribed and unnamed species, many of which could provide tomorrow’s foods and drugs, and many of which will be extinct in the next few decades. But even as humans colonise new soils, they use them for things other than food. New homes need new bricks, and new tiles, and new roads and sewers, and new landfill sites for rubbish, new pipelines for fuel, new quarries for cement and clay and minerals. About half of all humans will be city dwellers by the year 2000. Humans have become the biggest single earth-moving force on the planet, shifting more soil even than rainfall and rivers.
According to Roger Hooke of the University of Maine, rivers wash 24 billion tons of silt into the sea each year but humans now shift 35 billion tons of soil each year just to make roads, build houses and mine ores. This is six tons per human. So even as the demand for farmland grows, the space available for farms is consumed by, or mortgaged to, cities. This is called the “ecological footprint”.
Rich cities have a bigger footprint than poor ones. The ecological footprint for a Londoner is more than seven acres, according to William Rees of the University of British Columbia in Vancouver. So there is a need to get more and more food out of less and less farmland.
The Green Revolution was achieved by new rice, wheat and maize hybrids, watered by newly-engineered irrigation systems, fed by artificial fertilisers, protected by pesticides and tilled by oil-burning machines. Although yields are still high, there has been no increase in record yields for 20 years, and grain output per person is falling.
Oil demand will outstrip supply in about 2020, says John Edwards, once chief geologist with Shell Oil. Farmers use 150 million tons of phosphate each year: the world’s supplies could run out in 2050. And, far more ominous, there are already problems of water. It takes 1,000 tons of water to grow a ton of wheat. But cities and heavy industry are consuming more water than ever. The Colorado River is dry long before it reaches the sea. China’s Yellow river failed to reach the sea for 226 days in 1997: farmers and factories had taken it all.
Gretchen Daily of Stanford University, California, calculates that humans use one quarter of all the rain that falls from heaven and is taken up by plants: one quarter for humans, three quarters for the other 10 million species that share the planet. Half of all the accessible surface freshwater on the planet is consumed by humans. About 17 countries face “absolute” water scarcity. New dams could provide another 10% over the next 30 years, but by then the population will have grown by 45%. That is why the Nuffield Council on Bioethics last week urged the government to race ahead with research on new drought-tolerant, salt-tolerant, pest-resistant, protein-rich crops.
Prince Charles called this argument “emotional blackmail.” The charity Christian Aid condemned it, arguing that today’s hungry are surrounded by plenty, and that fairer distribution was a more urgent problem. This is true. The Worldwatch Institute in Washington recently calculated that if people in the US simply wasted one third less food each day, it would be enough to feed 25 million people, roughly the population of North Korea, recently in the grip of famine.
But in just under four months, the world would be home to another 25 million people, and four months after than, another 25 million, and so on. Two hundred years ago, Thomas Malthus wrote: “The power of population is so superior to the power in the earth to produce subsistence for man that premature death must in some shape or form visit the human race.” Five years ago, David Pimentel of Cornell University pointed out “Based on past experience, we expect that leaders will continue to postpone decisions on the human carrying capacity of the world until the situation becomes intolerable or, worse, irreversible.”