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’.
The UNCCD developed a definition of desertification as ‘land degradation in arid, semi-arid and sub-humid areas resulting from various factors including climatic variations and human activities’. The focus identifies a process resulting from many potential causes. Implicit is that desertification reflects a change in state, crossing a threshold in which original productivity is lost.
Much discussion uses the term ‘desertified’, where perhaps degradation would be more appropriate. This allows for changes in precipitation or land use (e.g. farmland left fallow or ending overgrazing) that may improve vegetation and pasture. As with several scientific terms that enter the popular lexicon, there is more nuance and shades of meaning to desertification than its usage suggests.
Two Oxford University researchers, Dave Thomas and Nick Middleton, wrote about this in ‘Desertification: Exploding the Myth’ in 1994, a book that highlighted the use and misuse of the term. Now over twenty years later the word is ever more popular and has become a shorthand way to say the environment has gone pear-shaped. Few writers take the time to look at contributory factors, from drought to conflict and war, poverty, intensive cultivation on unsuitable land and development pressures. Indeed, the term has become so generic that it has little real meaning.
A recent article of mine ‘Contraction of the Gobi 2000-2012’ showed how the size of East Asia’s largest desert has been decreasing due to increased precipitation (Sternberg et al. 2015). However, Chinese researchers were convinced that it was not precipitation but ‘good government anti-desertification policies’ that led to the shrinking of the desert.
In a recent visit to Oxford the UNCCD representative stressed ‘degradation in any environment’ rather than using the word ‘desert’. Where is the funding appeal for a dry or dessicated piece of land? Much better to rebrand desertification as a term for severe degradation. That implies the potential to change, reverse and improve landscapes through human action; a positive message the public can embrace.
On this day take a moment to think about the two billion people, predominantly poor, who live in marginal arid and semi-arid regions, to realise the implications of a term we use lightly.
Dr Troy Sternberg is a geographer researching desert environments and societies, based at the School of Geography and the Environment. His current focus is on how climate hazards impact landscapes and people across Asian drylands.
- Dr Troy Sternberg’s webpage
- Sternberg, T., Rueff, H. and Middleton, N. (2015) Contraction of the Gobi Desert, 2000-2012. Remote Sensing, 7(2): 1346-1358.
- United Nations Convention to Combat Desertification