"It has become more and more evident that desertification is one of the most important global challenges, destabilising societies the world over," said Van Ginkel, who is also rector of the United Nations University (UNU), a partner in the event involving around 200 experts from 25 countries.

Algerian President Abdelaziz Bouteflika, host of the conference, said that desertification "affects a third of the surface of our planet, more than the surface of China, Canada and Brazil combined," and is a threat to world peace.

Bouteflika called in a speech opening the event for a concerted, global effort, saying it was "more urgent that ever" to put into practice measures agreed at the 1992 Earth Summit in Rio de Janeiro to tackle desertification and preserve non-renewable resources.

Around 2 billion people live in areas threatened by desertification.

The implications for human migration are huge, with estimates today showing that migrants uprooted primarily by environmental factors now exceed the number of political refugees, according to a UNU statement.

Desertification has been on the world agenda for 50 years but efforts to arrest the problem have been chronically under-funded, and the situation is getting demonstrably worse every year, the organization said. It is still not known precisely how fast the process is unfolding, much less how best to address it.

One of those in attendance was Professor Rattan Lal of Ohio State University, who said poor developing-country households must switch to clean cooking fuels instead of burning crop residue and animal dung.

This will stop the loss of valuable sources of nutrients needed to forestall desertification and world hunger, Lal said.

By modestly improving soil quality in developing countries, an extra 20 to 30 million tonnes of food per year could be produced -- enough to feed the number of people being added to their populations annually -- at a cost of less than two billion dollars (1.5 billion euros) per year.

Karl Harmsen, director of UNU's Ghana-based Institute for Natural Resources in Africa, noted estimates that Africa may be able to feed just 25 percent of its population by 2025 if the decline in soil conditions continues on the continent.

Related Links
UN Covention to Combat Desertification
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