In his novel The Grapes of Wrath, John Steinbeck wrote about the US Dust Bowl of the 1930s and how families were driven off the land. It scored him a Pulitzer and was cited by the Nobel committee in awarding him the 1962 prize for literature.
In the wake of the Great Depression, the Midwestern United States suffered the hottest and driest weather on record and crops failed. Cattle had been allowed to graze freely across the plains, even in the dry months, eating what little cover there was, leaving the soil exposed.
As a result, across an area of 50million acres, wind blew the topsoil into intense dust storms sometimes called ‘haboobs’.
The haboobsare returning. Last month NASA filmed one from space: a moving mountain of sand 200 miles wide and swirling up to a mile high. It covered roads and buildings, silted dams and damaged crops.
According to the BBC Radio 4 programme, Inside Science, the cause is man-made.
‘The irony is that, in much of the Mid-West, expansion of maize production has been encouraged by bio-fuel incentives, intended to offset global warming,’ presenter Roland Pease told listeners. ‘And as other researchers have noted, this has meant grasslands with year-round cover have been ploughed up to make way for seasonal crops: echoes of what happened when tractors first arrived on the Great Plains.’
As in the 1930s, the affected area covers North and South Dakota, Kansas, Nebraska, Iowa, western Minnesota and part of Colorado.
At the University of Utah, Andy Lambert wrote a thesis on atmospheric dust. He says the level at which large particles in the atmosphere become a risk is set by the US Environmental Agency and has rarely been exceeded in the past. ‘Now they are being exceeded once or twice every few years across many of the Great Plains states,’ he said.
In another paper, Lambert said the expansion of crops in arid areas lay at the heart of the problem. Winds lifting the sand also strip away the nutrients for vegetation growth that help to stabilise the soils. ‘This is the same thing we saw in the 1930s.’
In 1933, Congressman Edward Taylor introduced the Bill that still bears his name, licensing the use of pastures and, in marginal areas, limiting cattle to feed lots.
Eventually the dust settled, the grass came back, nature was allowed to restore a balance that had worked for millennia and haboobs became a thing of history. But the rush for biofuels in an effort to combat climate change has once again ripped away the protective layer.
NASA has also logged an increase in sandstorms across Africa. On a continent where an estimated 600million people lack electricity, firewood is used for cooking and to heat homes and the loss of trees has seen a rapid spread of desert. Along the edge of the Sahara, winds of up to 60mph move the dunes in such volume that they strip paint from cars and buildings. Forbes magazine warned that sand from the Sahara was moving fast and high enough to reach the US.
On its website, NASA blames the problem on ‘cutting of trees and overgrazing’, adding that ‘without vegetation to anchor the soil in place, wind erosion scours away the topsoil’.
According to the World Wide Fund for Nature (WWF), up to half a billion acres in Africa could be earmarked for projects similar to those in the United States. The African savanna, like the prairies, sustains a complex ecosystem that if disturbed could lead to similar problems. Large areas of Zimbabwe, Mozambique, Kenya and Tanzania have never been farmed intensively, with locals grazing cattle and growing market crops on a scale compatible with the land.
At the Global Warming Policy Foundation in London, director Benny Peiser said he was ‘pleasantly surprised at the accuracy and balance’ of the BBC report.
‘The BBC almost habitually exaggerate the influence of climate change in their coverage,’ he said. ‘For once they looked at the main cause behind an event.’