ENVIRONMENT: New Desert Storms in the Making

By Sanjay Suri Reprint | | Print |

Sanjay Suri

LONDON, Aug 26 2004 (IPS) - A four-wheel drive vehicle turns off the road and into the desert. A cloud of dust follows. In time such clouds contribute to a desert storm. Right or wrong?

Right, says Prof Andrew Goudie, professor of geography at Oxford University.

”Many desert surfaces have a protective layer that consists of lichen, clay, algae, pebbles etc.,” Goudie told IPS. ”This sits over materials that contain a lot of fine silt. When vehicles expose the underlying material to strong wind action, the dust is blown up.”

This is undoubtedly a big factor in areas around big cities, he said. ”There is a tremendous amount of activity around cities like Cairo and Riyadh.”

Goudie calls this phenomenon the ”Toyotorisation” of the desert.

”I am quite serious, you should look at deserts from the air, scarred all over by wheel tracks, people driving indiscriminately over the surface, breaking it up,” Goudie told the International Geographical Congress in Glasgow last week. ”If I had my way I would ban them from driving off-road.”

Heavy use of four-wheel drives is a problem in these particular situations, though ”there is very little information on just how much of the damage is being caused by vehicles,” Goudie told IPS. Four-wheel drives were causing serious damage, but are not the principal offender, he said.

”They are not the reason for dust arising from central Sahara,” Goudie said. The four-wheel drives are only exacerbating a bigger problem arising in the Sahara and other large deserts.

”The Sahara is the main source of dust,” Goudie said. Recent studies have shown that dust in the atmosphere arising from the Sahara has risen tenfold since the late 1940s. Up to three billion tonnes of dust is kicked up into the atmosphere every year, he said.

The massive increase in dust storms arising from the Sahara is a result of climate change and not direct human activity, he said, unless it was other human activity contributing to climate change.

The implications are far-reaching. Dust storms arising in the Sahara have carried dust 5,000 km to damage coral reefs as far away as the Caribbean, Goudie’s studies show.

Saharan dust is often visible in many areas around the world, Goudie says. It is casting a red haze over the Alps in Europe. Britain too is beginning to see such ”blood rain”.

The dust would therefore seem to keep close company with carbon emissions. But the dust deposit in the atmosphere may not lead to global warming in the same way that carbon emissions are believed to cause, Goudie said.

The dust reflects sunlight back but at places also holds the heat in. The net result may often be cooling rather than warming, Goudie said. But that is not necessarily good because it affects the temperature profile above earth.

Goudie pointed out in his presentation that the single biggest source of dust is the Bodele area close to Lake Chad. The lake is now estimated to be down to 5 percent of its surface area in the 1960s. This area alone releases close to half the dust in the atmosphere above earth.

Salt carried with the dust from such areas can damage agricultural produce in far distant places, according to Goudie’s research. That in turn can lead to more deserts and more dust.

People who have breathed in dust from the drying Aral Sea in Central Asia have reported serious allergic reactions. Dust storms in the United States have often caused allergic reactions from the pesticides they carry, Goudie says.

The dust often carries with it microbes and pesticides that can cause infections thousands of miles from their source. A typical dust storm is 200 km wide and usually carries between 20 million to 30 million tonnes of dust.

Several other factors are also damaging deserts. In semi-arid areas such as Rajasthan in India, overgrazing is causing serious damage, Goudie said. A population of several hundreds per square kilometre and the large number of cows, goats and sheep are also laying desert surfaces bare to generate dust storms.

Desertification and its consequences are not getting worse everywhere. ”In some places like Australia, America, even China, dust levels have gone down,” he said. ”This is largely due to changing climate patterns and improved agricultural production.”