Earth Science News  





. Global Warming And Deserts Are A Double-Edged Sword

File photo: Desertification in the Mediterranean.
by Anne Chaon and Richard Ingham
Paris (AFP) Jun 20, 2006
The desert is a special word, reflecting our dread and awe at vast, parched regions where a few plants, animals and hardy humans somehow survive in the emptiness. These conflicting emotions find resonance this Saturday in a UN day that celebrates the desert yet curses desertification and points to the impact of climate change on both.

Man-made global warming is set to accelerate desertification - some experts say this is probably already the case - yet paradoxically it also threatens deserts themselves, placing unique wildlife and cultures in peril.

Desertification is as old as human civilisation itself, dating back to earliest arable farming in Mesopotamia 5,000 years ago.

In the past quarter-century, though, the problem has become acute.

Drylands, areas with low rainfall and high evaporation that are on the fringes of the desert, account for 41 percent of Earth's land area, 43 percent of its cultivated surface and are home to more than two billion people, mostly in poor countries.

But between 10 and 20 percent of drylands are already classified as degraded, meaning that their ability to produce crops has been wiped out or severely reduced.

Land degradation causes crop losses of around 42 billion dollars a year, according to the UN Environmental Programme (UNEP). "The Sahel countries have had a drought that has now persisted for 25-35 years with between 10 and 20 percent less rain than before, and semi-desert regions have advanced southwards by 100 kilometres (60 miles)," said Gil Mahe, a desertification specialist at France's Institute for Development (IRD).

The cause lies mainly with dust storms that overwhelm dry vegetation (and, in the case of the advancing Gobi desert, can choke Beijing for days at a time). Salt deposited on fields through over-irrigation is another factor.

But the problem is set to worsen in many countries this century, as rainfall patterns shift, evaporation increases and water runoff from glaciers decreases.

"The probability of regions in the interiors of continents becoming desert will increase," says Ronald Prinn, New Zealand-born co-director of the Joint Program on the Science and Policy of Global Change (JPSPGC) at Massachusetts Institute of Technology (MIT).

According to the UN's science body, the Intergovernmental Panel on Climate Change (IPCC), temperatures in deserts could rise by an average of up to five to seven C (nine to 12.6 F) by 2071-2000 compared to the period 1961-1990.

Many deserts will suffer a decline in rainfall between five and 10 or even 15 percent, it predicts. Australia's Great Victoria desert, the Atacama and the arid Colorado Great Basin region of the southwestern United States will be most hit, although the Gobi is predicted to have rainfall increases of between 10 and 15 percent by the end of the century.

Mahe insists it is possible to fight desertification, provided countries "mobilise massively" to build stone dikes, plant coarse grass, hedges, shrubs and trees to act as natural barriers.

And they must also be patient - the results take between one and three decades to take effect - and willing to practise low-intensity agriculture in recovered land, he said.

"In northern Burkina Faso and Niger, people are growing crops in land that was abandoned in the past. In the same region, you can see stretches of land that have been abandoned and others that have been protected by good practices," said Mahe.

Saturday's World Day to Combat Desertification coincides with 2006 as the UN International Year of Deserts.

Marking that, a new UNEP report, Global Desert Outlook, says the cores of deserts represent some of the world's last pristine areas of total wilderness, yet many of its species could be imperilled by human incursion or development.

One such threat is the diversion of large rivers that cross deserts to help water-stressed cities and farms. These rivers create unique desert wetlands such as the Aral Sea and the marshlands of Iraq.

Source: Agence France-Presse

Related Links
UN Environmental Programme

Experts Call On World Leaders To Curb Advancing Deserts
Tunis (AFP) Jun 20, 2006
Experts at a world conference here on desertification Monday called for political leaders to use the technical tools available to stem the merciless advance of parched land and its devastating social, economic and human consequences.

.
Get Our Free Newsletters Via Email
  



  • National Guard To Return To New Orleans To Fight Crime
  • US Not Prepared For Catastrophe Finds Official Report
  • UN Launches Campaign For Disaster-Proof Schools
  • Hurricane Damage Mininized By Sticking To The Rules

  • Experts Call On World Leaders To Curb Advancing Deserts
  • Global Warming And Deserts Are A Double-Edged Sword
  • Thawing Permafrost Is A Significant Source Of Carbon
  • Living With Climate Variability And Change

  • NGOs Using Satellite Imagery To Plan Agriculture Relief Efforts
  • ESA And Spot Image Set Precedence With Data Sharing
  • High-Flying Satellites Give Land Managers The Low-Down On Cheatgrass
  • NASA Missions Help Dissect Sea Level Rise

  • Looming Energy Crisis Requires New Manhattan Project
  • Rural Kenyan Women On Vanguard Of African Solar Revolution
  • France Boosts Purchase Rates To Spur Renewable Energy
  • Europe Sets Up Task Force for Solar Energy

  • China Reports New Bird Flu Outbreak
  • High Virulence Of HIV-1 Might Be An Accident Of Evolution
  • H5N1 Not In US Migratory Birds
  • US Approves Wild Bird Avian Flu Surveillance Network

  • Researchers Offer Clues To How Leaves Patterns Are Formed
  • Global Warming May Warrant New Approaches To Ecosystem Restoration
  • Aromatic World
  • Recreation Of Butterfly Speciation Event

  • Blast At China Chemical Factory Raises Pollution Fears
  • Coal Tar Spillage Contaminates Northern Chinese River
  • Sandia Tool Speeds Up Environmental Cleanup, Reopening Of Contaminated Facilities
  • India Court Allows Toxic Ship Into Territorial Waters

  • Satellite Guidance For The Visually Impaired
  • To Profit Or Explore Might Be The Meaning Of Life
  • Evidence Human Activities Have Shaped Large-Scale Ecological Patterns
  • Ancient Human Fossils Find Modern Virtual Home

  • The content herein, unless otherwise known to be public domain, are Copyright 1995-2006 - SpaceDaily.AFP and UPI Wire Stories are copyright Agence France-Presse and United Press International. ESA PortalReports are copyright European Space Agency. All NASA sourced material is public domain. Additionalcopyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by SpaceDaily on any Web page published or hosted by SpaceDaily. Privacy Statement