The desert is making a comeback in the Middle East, with fertile lands turning into barren wastes that could further destabilise the region, experts said at a water conference on Thursday.
"Desertification spreads like cancer, it can't be noticed immediately," said Wadid Erian, a soil expert with the Arab League, at a conference on Thursday in the Egyptian coastal town of Alexandria.
Its effect can be seen in Syria, where drought has displaced hundreds of thousands of people, ruining farmers and swelling cities, Erian said.
He said Darfur in western Sudan is still reeling from a devastating war exacerbated by a shortage of water and fertile land.
The United Nations Development Programme's 2009 Arab Human Development Report said desertification threatened about 2.87 million square kilometres of land (1.15 million square miles) -- or a fifth of the Middle East and north Africa.
Erian said a large portion of rangeland and agricultural land was under threat, with little effort taken so far to reverse the process.
Burgeoning populations, which put further strain on the environment, and climate change are accelerating the trend, he said.
"The trend in the Arab world leans towards aridity. We are in a struggle against a natural trend, but it is the acceleration that scares us," he said.
"Most Arab countries until 2006 dealt with it as one problem among many. Then agriculture ministers described it as a danger threatening the Arab world. That is because they began to feel pain."
A 2007 UN study spoke of an "environmental crisis of global proportions" that could uproot 50 million people from their homes by 2010, mostly in Africa.
Erian said that if unchecked, the trend could emerge as a threat to international stability, a conclusion shared by the UN report.
"It will lead to more immigration and less security. It will lead to people losing hope," he said.
Fatima el-Malah, a climate change adviser for the Arab League, said despite its impact donor countries have not dealt with desertification as a priority.
Programmes by the United Nations Convention to Combat Desertification were underfunded, she said. "They said just draw a plan and we'll fund you. There was never any funding."
Explore further: Mexico sets greenhouse gas target for UN climate talks