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Are Deserts Expanding?

Already one third of the world is considered desert and many deserts are expanding.

The Gobi desert in China has expanded every decade since the 1950s. In a 5 year period ('94-'99) the Gobi desert expanded over 20,000 square miles (1). In 5 years that's an area larger than New Jersey and Massachusetts combined! More importantly, the desert is about 150 miles from Beijing and still expanding.

The Sahara desert in Northern Africa has spread South over 250,000 square miles in the past 50 years(2). As it is, the Sahara is the largest desert in the world at 3.5 million square miles, larger than the continental United States (3).

The growth of deserts is called desertification, which means that a region is transformed into an arid or dry region. Our current deserts formed from hundreds upon thousands of years of climate change. But it's not always a natural process that causes desertification.

More recently humans are thought to have caused, in some part, the growing of some deserts (2). It's the way we use, or overuse more appropriately, the land. Farmers will not rotate their crops in some countries, which usually gives the soil a chance to replenish it's nutrients. But the need for food is too great and thus the land is over-farmed. Or animals overgraze the land, removing vegetation which traps moisture. Or the trees and shrubs are used for fuel which exposes the top soil.

Are Deserts Expanding From Global Warming?

In the link (2) cited below, the article mentions "the world is becoming warmer and drier, and this means there is less water to support plants and animals". This is not necessarily true. In fact, long range forecasting models predict that along with global warming comes a wetter world. Although the moisture may not be spread equally across the globe, while some deserts might expand, so too would some rain forests. Furthermore, according the US Environmental Protection Agency, little research has been done on how global warming might affect deserts. The EPA even points out that while one model shows an increase in deserts by 185%, another shows a decrease by 56% (4).With such uncertainty I believe it is too difficult to determine how much if any of desertification is due to global warming.


(1) http://www.ieca.org/Resources/Article/ArticleChinaAdvancingDeserts.asp

(2)http://www.oxfam.org.uk/coolplanet/ontheline/explore/nature/deserts/prtconserve_desertification.htm

(3) http://www.mrdowling.com/607-deserts.html

(4) http://yosemite.epa.gov/OAR/globalwarming.nsf/content/ImpactsDeserts.html