Photo credit: Water
The Gobi Desert. Photo by Nanel
Desertification: the environment gone pear-shaped?
On 17 June, World Day to Combat Desertification, Dr Troy Sternberg asks some important questions. What is desertification? Is it caused by climate or humans? Are deserts taking over? Can the process be stopped?
The idea of desertification came in the 1970s when scientists noted that parts of the Sahara Desert appeared to be expanding by kilometres per year. News reports and popular imagination extrapolated the numbers and declared that deserts were spreading at alarming rates. Articles began, ‘at this rate, in 10 years (choose your favorite African city) will be covered in sand.’
In 1994 the United Nations created the Convention to Combat Desertification (UNCCD) to address the issue. Soon the term was applied to China and India, the American Southwest and the Middle East. Desertification had captured the public’s imagination and became the go-to term for ‘something’s happening in the desert.’
In time, science and climate knowledge diverged from popular perceptions of desertification. With interest, investigation and new techniques, like satellite imagery, researchers were able to better understand climate and landscape interaction in arid regions. Two important factors became clear: (1) climate variability, particularly in precipitation, resulted in fluctuations in land cover, and (2) humans had significant impact on desert environments.
The first point, now broadly acknowledged, highlights how climate affects vegetation patterns. With more rain plant cover increases, while in dry or drought years ecological productivity decreases. Thus in wetter years deserts ‘shrink’ whilst ‘expanding’ in drier years.
The second point stresses the huge impact people have on landscapes, especially drylands. Agriculture, livestock grazing, resource extraction, urbanisation and intensive land use all affect desert environments. Once damaged, marginally productive arid landscapes are unlikely to recover.
Soon the idea of desertification grew in complexity. It was not a simple case of ‘deserts taking over’ or just a ‘climate event’. One year’s ‘desertification’ might be replaced by the next year’s ‘greening’.
Read the full article: Water