[rhinoceros] I noticed this recent article in New Scientist.
Africa's deserts are in "spectacular" retreat
by Fred Pearce
18 September 02
The southern Saharan desert is in retreat, making farming viable again in what were some of the most arid parts of Africa.
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.
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 Andrew Warren of University College London told New Scientist that the unpublished analysis shows that "vegetation seems to have increased significantly" in the past 15 years, with major regrowth in southern Mauritania, northern Burkina Faso,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.
[rhinoceros] Things did not look so green in a previous article, also from New Scientist. Is there a contradiction or is it one of the rare cases when things actually get better? What do you think?
African droughts "triggered by Western pollution"
by Rachel Nowak, Melbourne
12 June 02
Emissions spewed out by power stations and factories in North America and Europe may have sparked the severe droughts that have afflicted the Sahel region of Africa. The droughts have been among the worst the world has ever seen, and led to the infamous famines that crippled countries such as Ethiopia in the 1980s.
The cause appears to be the clouds of sulphur belched out alongside the soot, organic carbon, ammonium and nitrate produced when fossil fuels are burnt, according to researchers in Australia and Canada. As these compounds move through the atmosphere, they create aerosols that affect cloud formation, altering the temperature of the Earth's surface and leading to dramatic shifts in regional weather patterns.
In the past thirty to forty years, the Sahel--a loosely defined band across Africa, just south of the Sahara and including parts of Ethiopia in the east and Guinea in the west--has suffered the most sustained drought seen in any part of the world since records began, with precipitation falling by between 20 and 50 per cent.
Although the droughts have had climate experts scratching their heads, the impacts have been obvious. During the worst years, between 1972 and 1975, and 1984 and 1985, up to a million people starved to death.
During the past few years, the droughts have become less severe, a change that Rotstayn puts down to the "clean air" laws in North America and Europe that reduced sulphur dioxide emissions in response to another environmental crisis, acid rain.
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