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Deserts can become solar power houses, says UN
Posted: 19 Jun 2006

The world’s deserts are facing dramatic changes as a result of global climate change, high water demands, tourism and salt contamination of irrigated soils. Desert margins and so called ‘sky islands’ - mountain areas within deserts that have been important for people, wildlife and water supplies for millennia - are under particular threat, according to Global Deserts Outlook, a new report by the United Nations Environment Programme (UNEP).

Not all the changes need necessarily be harmful. Some may have clear benefits for indigenous people and other desert residents, and even the wider world. Most deserts have sunlight and temperature regimes that favour - possibly surprisingly - sites for shrimp and fish farms in locations like Arizona to the Negev desert in Israel.

Such ventures offer new and potentially environmentally-friendly livelihoods for local people and businesses. Eventually these and other developments that make use of the unique features of deserts could also help relieve the pressure on mangroves and sensitive coastlines which are currently being cleared for shrimp ponds.

Meanwhile some experts believe deserts could become the carbon-free power houses of the 21st century. They argue that an area 800 by 800 km of a desert such as the Sahara could capture enough solar energy to generate all the world’s electricity needs and more.

Shafqat Kakakhel, UNEP’s Officer in Charge and Deputy Executive Director,
said: “There are many popular and sometimes misplaced views of deserts which this report either confirms or overturns. Far from being barren wastelands, they emerge as biologically, economically and culturally dynamic while being increasingly subject to the impacts and pressures of the modern world”.

Salinization of desert soils: a Sindhi cowherd and grazing cattle on a former rice field. Photo: © UNEP/Andrew Warren

Mr Kakakhel cited the growing interest in deserts as prime locations for aquaculture and the source of novel drugs, herbal medicines and industrial products derived from the plants and animals adapted to these arid areas.

“If the huge, solar-power potential of deserts can be economically harnessed the world has a future free from fossil fuels. And tourism based around desert nature can, if sensitively managed, deliver new prospects and perspectives for people in some of the poorest parts of the world,” he added.

Many of the changes that deserts could experience are likely to be far less positive unless they are better controlled. Population growth and inefficient water use are, by 2050, set to move some countries with deserts beyond thresholds of water stress, or even worse, water scarcity. 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 southwestern Asia and the Amu Darya and Indus Rivers in central Asia.

Historic and projected human impacts in deserts. Click on image to see larger version.

Better management of water supplies will be the key challenge for the future of deserts but could, if successful, be a beacon of hope and good practice for other water-short parts of the globe.

Some key facts from the Global Deserts Outlook

Almost one-quarter of the earth’s land surface – some 33.7 million square kilometres – has been defined as “desert” in some sense. These deserts are inhabited by over 500 million people, significantly more than previously thought.
The desert cores remain pristine in many parts of the world, representing some of the planet’s last remaining areas of total wilderness.
The desert fringes in many places, however, suffer high pressures from human activities and include several of the most threatened terrestrial ecoregions of the world.

Projected climate change in deserts. Click on image to see larger version.

Climate change

Climate change as a result of human-made emissions is already affecting deserts.
The overall temperature increase of between 0.5 and two degrees C over the period 1976-2000 has been much higher than the average global rise of 0.45 degrees C.
The Dashti Kbir desert in Iran has seen a 16 per cent fall per decade in rainfall during this same period; the Kalahari in South Africa a 12 per cent decline and the Atacama desert in Chile, an 8 per cent drop.
In contrast Kizil Kum in Afghanistan and the Western Desert in Egypt have seen a 4 to 8 per cent rise over the same period.
Profound changes with important implications for water supplies and people, and desert plants and animals, are likely in some regions unless greenhouse gas emissions are dramatically reduced.
Under scenarios developed by the Intergovernmental Panel on Climate Change (IPCC), the body of scientists advising governments and the United Nations, temperatures in deserts could rise by an average of as much as 5 to 7 degrees C by 2071-2100, compared to the average in the period 1961-1990. Many deserts will see declines in rainfall of between 5 and 10 or even 15 per cent with deserts in southerly latitudes especially vulnerable.

Most of the 12 desert regions, whose future climate has been modelled, are facing a drier future with rainfall in some cases forecast to be 10 to 20 per cent lower by the end of the century.
The problem will almost certainly be compounded by the melting of glaciers whose waters sustain many deserts such as the Atacama and Monte Deserts in South America.

The situation is being aggravated by overgrazing and the cutting of trees and other vegetation in these desert mountain realms thus reducing the capacity of these natural water towers.

The report adds: “A large fraction of the water used for agricultural and domestic purposes in the arid Southwest of the United States, the deserts of Central Asia and the Atacama and Puna Deserts on both sides of the Andes is drawn from rivers that originate in glaciated/snow-covered mountains”.

Other impacts of climate change include the turning of some semi-arid rangelands into deserts and the re-mobilization of dunes currently stabilized by vegetation as in the southwestern Kalahari Desert in southern Africa.