|Source||John K. Doherty|
|Africa's deserts are in "spectacular" retreat
18 September 02
Exclusive from New Scientist Print Edition
The southern Saharan desert is in retreat, making farming viable again in what were some of the most arid parts of Africa.
Vegetation is starting to conquer the dunes.
Burkina Faso, one of the West African countries devastated by drought and advancing deserts 20 years ago, is growing so much greener than families who fled to wetter coastal regions are starting to go home.
New research confirming this remarkable environmental turnaround is to be presented to Burkina Faso's ministers and international aid agencies in November. And it is not just Burkina Faso.
New Scientist has learned that a separate analysis of satellite images completed this summer reveals that dunes are retreating right across the Sahel region on the southern edge of the Sahara desert. Vegetation is ousting sand across a swathe of land stretching from Mauritania on the shores of the Atlantic to Eritrea 6000 kilometres away on the Red Sea coast.
Nor is it just a short-term trend. Analysts say the gradual greening has been happening since the mid-1980s, though has gone largely unnoticed. Only now is the evidence being pieced together.
Firewood and grassland
Aerial photographs taken in June show "quite spectacular regeneration of vegetation", in northern Burkina Faso, according to Chris Reij of the Free University, Amsterdam.
There are more trees for firewood and more grassland for livestock. And a survey among farmers shows a 70 per cent increase in yields of local cereals such as sorghum and millet in one province in recent years. The survey, which Reij is collating, was paid for by Dutch, German and American overseas aid agencies.
Meanwhile, Kjeld Rasmussen of the University of Copenhagen has been looking in detail at sand dunes in the same area. Once they seemed to be marching south. But since the 1980s, he says, there has been a "steady reduction in bare ground" with "vegetation cover, including bushes and trees, on the increase on the dunes".
Desertification is still often viewed as an irreversible process triggered by a deadly combination of declining rainfall and destructive farming methods. In August, the UN Environment Programme told the World Summit in Johannesburg that over 45 per cent of Africa is in the grip of desertification, with the Sahel worst affected.
But a team of geographers from Britain, Sweden and Denmark has spent the summer re-examining archive satellite images taken across the Sahel. Andrew Warren of University College London told New Scientist that the unpublished analysis shows that "vegetation seems to have increased significantly" in the past 15 years, with major regrowth in southern Mauritania, northern Burkina Faso, north-western Niger, central Chad, much of Sudan and parts of Eritrea.
But there is confusion over why the Sahel is becoming green. Rasmussen believes the main reason is increased rainfall since the great droughts of the early 1970s and 1980s. But farmers have also been adopting better methods of keeping soil and water on their land.