The Global Deserts Outlook, produced by the UN's Environment Programme, is
described as the first comprehensive look at the Earth's driest regions.
It highlights the problems - and also the potential - in arid areas.
The authors call for more careful use of scarce water resources to safeguard
the futures of desert populations.
"Far from being barren wastelands, [deserts] emerge as biologically,
economically and culturally dynamic while being increasingly subject to the
impacts and pressures of the modern world," said Shafqat Kakakhel, from Unep.
"They also emerge as places of new economic and livelihood possibilities,
underlining yet again that the environment is not a luxury but a key element
in the fight against poverty and the delivery of internationally-agreed
The report defines deserts in three ways:
- Climatologically, as the arid and hyper-arid areas of the globe
- Biologically, as ecoregions that contain plants and animals adapted
to an arid existence
- Physically, as those areas with ample extensions of bare soil and
low vegetation cover
Taken together, these areas give a composite definition of global deserts,
occupying almost one-quarter of the Earth's land surface - some 33.7 million
sq km (13 million sq miles) - and inhabited by over 500 million people.
Most of them live at desert margins and it is here that some of the
pressures threatening ecosystems in arid areas are at their greatest.
Population growth and inefficient water use are, by 2050, set to move
some countries with deserts into water stress, or even worse, water
scarcity, the report says. Examples include Chad, Iraq, Niger and Syria.
Renewable supplies of water which are fed to deserts by large rivers are
also expected to be threatened, in some cases severely, by 2025.
Examples include the Gariep River in southern Africa; the Rio Grande and
Colorado Rivers in North America; the Tigris and Euphrates in south-western
Asia and the Amu Darya and Indus Rivers in central Asia.
One of the report's author's, Professor Andrew Warren from University
College London, said that without careful management in the future, the
unique landscapes, ancient cultures, flora and fauna in these areas were at
risk of disappearing.
"What alarms me now is that they are threatened as never before by
climate change, by over-exploitation of groundwater, salinisation and the
extinction of wildlife," he said.
However, the report concludes that although some trends are worrying,
other changes likely to occur in the next 50 years could be positive.
There are new economic opportunities, it says, such as shrimp and fish
farms in Arizona in the US and in the Negev Desert in Israel, offering
environmentally friendly livelihoods for local people.
Desert plants and animals are being seen as positive sources of new drugs
Nipa, a salt grass harvested in the Sonoran desert of north western
Mexico at the delta of the Colorado River by the Cocopahs people, thrives on
pure seawater, producing large grain yields similar to wheat.
"It is a strong candidate for a major global food crop and could become
this desert's greatest gift to the world," the report says.
Even the problems of global warming could be tackled by better use of
deserts: some experts say that an area of the Sahara 800km by 800km (500
miles by 500 miles) could capture enough solar energy to meet the entire
world's electricity needs.
Nonetheless, climate change is seen a major hurdle for desert ecosystems
in the years ahead.
Most of the 12 desert regions whose climate has been modelled are facing
a drier future.
The overall temperature increase in desert regions of between 0.5 and 2C
over the period 1976-2000 has been much higher than the average global rise
of 0.45C, the report says.
Story from BBC NEWS:
Published: 2006/06/05 01:44:15 GMT
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The full Global Desert Outlook report is available from the UNEP web site.