Soil erosion as big a problem as global warming, say scientists

Erosion of topsoil - already a serious problem in Australia, China and parts of the US - threatens modern civilisation as surely as it menaced societies long since vanished, researchers warned yesterday.

Jared Diamond, a physiologist at University of California Los Angeles and author of Guns, Germs and Steel, told the American Association for the Advancement of Science yesterday that Iraq, part of the Fertile Crescent in which agriculture started 10,000 years ago, was once the wealthiest, most innovative, most advanced country in the world. But today it was a "basket case", mainly because of "soil problems, salinisation, erosion, coupled with problems of deforestation".

Soil loss

Eroded land in Ethiopia - 40 per cent of global productive land is affected. Photo � Sean Sprague / Panos Pictures

Although more than 99 per cent of the world's food comes from the soil, experts estimate that each year more than 10m hectares (25m acres) of crop land are degraded or lost as rain and wind sweep away topsoil. An area big enough to feed Europe - 300m hectares, about 10 times the size of the UK - has been so severely degraded it cannot produce food, according to UN figures.

In many places, soil is being lost far faster than it can be naturally regenerated.

Attempts to irrigate arid lands have produced soils so salty that nothing will grow.

One speaker, Ward Chesworth of the University of Guelph, Ontario, told the conference that farming had produced an "agricultural scar" on the planet that affected a third of all suitable soils.

Societies in the past had collapsed or disappeared because of soil problems. Easter Island in the Pacific was a famous example, Prof Diamond said. Ninety per cent of the people died because of deforestation, erosion and soil depletion.

"Society ended up in cannibalism, the government was overthrown and people began pulling down each other's statues, so that is pretty serious. In another example, Pitcairn and Henderson island in the south-east Pacific, everybody ended up dead. Another example was Mayan civilisation in the Yucatan peninsula of Mexico and Guatemala. Again, people survived but about 90 per cent of the population was lost," he said.

Other examples, he said, include Iceland, where about 50 per cent of the soil ended up in the sea. Icelandic society survived only through a drastically lower standard of living.

He said the media focused on fossil fuel problems, climate change, biodiversity, logging and forest fires, but not on the soil because it was less spectacular.

"There are about a dozen major environmental problems, all of them sufficiently serious that if we solved 11 of them and didn't solve the 12th, whatever that 12th is, any could potentially do us in," he said. "Many of them have caused collapses of societies in the past, and soil problems are one of those dozen."

Tim Radford is Science Editor at The Guardian.

Guardian Unlimited � Guardian Newspapers Limited 2004 . This article was first published in The Guardian, (Saturday, February 14 2004). All rights reserved. Reproduced with kind permission.

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