"Human activities such as overcultivation, overgrazing, deforestation and poor irrigation practices, along with climate change, are turning once fertile soils into unproductive and barren patches of land," Mr. Annan said in a message marking World Day to Combat Desertification and Drought, with this year's theme being "Sustainable water resource management schemes."
He noted that all parts of the world are affected - Australia, where last year's drought was the worst in more than a century and millions of tons of productive topsoil blew away in dust storms; India, where dry spells and deforestation turn 2.5 million hectares into wasteland every year; Mexico, where 70 per cent of all land is vulnerable to desertification, prompting 700,000 to 900,000 Mexicans to leave their homes every year in search of a better living as migrant workers in the United States.
But nowhere, he warned, is the problem of desertification more acute than in sub-Saharan Africa, where the number of environmental refugees is expected to rise to 25 million in the next 20 years.
"Because the poor often farm degraded land that is increasingly unable to meet their needs, desertification is both a cause and a consequence of poverty," Mr. Annan said. "Fighting desertification must, therefore, be an integral part of our wider efforts to eradicate poverty and ensure long-term food security.
"Let us today recommit ourselves to the goals of the Convention, and to achieving sustainable development for all, including in the dryland rural areas where the world's poorest people live," he concluded, referring to the 1994 UN treaty to combat desertification.