Reuters

London, Jun 7: Far from being barren wastelands, the deserts that occupy one quarter of the earth's land surface could be key sources of food and power, the United Nations said on Monday.

But these vast open spaces, home to rare and useful plants and animals, are at risk from climate change and human exploitation, the UN's Environment Programme said in a report published on World Environment Day.

Deserts are prime potential locations for solar power generators that do not pollute the atmosphere with greenhouse gases, and plants that can thrive in desert conditions could provide food when water runs short.

One such, a plant called Nipa found in the Sonoran desert of western Mexico, produces a grain the size of wheat but is drought resistant and even thrives on seawater.

"It is a strong candidate for a major global food crop and could become this desert's greatest gift to the world," the report said.

Rainfall patterns are changing, glaciers that feed important rivers are melting as the planet warms and irreplaceable water from deep desert aquifers is being squandered.

Rainfall in Iran's Dashti Kibri desert dropped by 16 per cent a decade between 1976 and 2000. In South Africa's Kalahari and Chile's Atacama deserts it fell by 12 and 8 per cent respectively, the report said.

The Rio Grande river in the United States has dwindled to a saline trickle from a freshwater torrent, and South Africa's Orange river is also shrinking.

Fighting for water

"The answer to desert water is to stop using it stupidly," said specialist Andrew Warren of University College London.

"Saudi Arabia exports water in the wheat it grows using irrigation ... Jordan exports much of its water in the form of tomatoes,'' he added, noting that as over-exploited water sources retreated, the water became more salty and less useable.

It said that in China's Tarim River basin more than 12,000 square km of land had been salinised over the past 30 years.

The energy-intensive desalination plants which turn salt water into fresh water in some energy-rich countries in the West Asia are not generally attractive in an era when energy prices are rising rapidly.

As well as biodiversity, human societies are at risk. The cultures of desert dwellers around the world are threatened by reduced rainfall and over-exploitation, and dwindling resources could generate local wars, the report warned.

"There is going to be a fight for water - there already are such fights," Warren said.

Pakistan, already one of the most water-stressed countries in the world, is facing even more problems as groundwater levels fall and glaciers retreat.

"There will be increased competition for water resources," Warren said. "It is not the most stable region. There will be really nasty implications."