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The conventional wisdom on the causes of widespread desertification is false.

 

Photo credit: ILRI

Goats graze drylands in the dry season in Zimbabwe (photo credit: ICRISAT/Swathi Sridharan).

The picture of the Sahara as marching inexorably south year after year is incorrect and was, moreover, an illusion created not by livestock over-use but rather by a recent string of dry years. Indeed, decades of satellite data are now confirming that the southern edge of the Sahara periodically moves south and north in response to changes in rainfall rather than changes in livestock populations. It thus appears that the conventional wisdom on the causes of widespread desertification is false.
—ILRI article, 1995

‘Desertification’—A timely synthesis of three decades of evidence that this topic has (long) passed its sell-by date

by

Ian Scoones reviews a new book on the long history of myths about dryland desertification. Scoones, co-director of the STEPS Centre at Sussex and joint convenor of the Future Agricultures Consortium hosted by the Institute for Development Studies, is an agricultural ecologist by training and an ‘interdisciplinarian’ by practice. ‘Over the past twenty-five years, he has worked on pastoralism and rangeland management, soil and water conservation, biodiversity and conservation, as well as dryland agricultural systems, largely in eastern and southern Africa. A central theme has been a focus on citizen engagement in pro-poor research and innovation systems.’ 

Excerpts from Scoones’ excellent review, with its important messages, follows.

‘A great new book has just been published called The End of Desertification? Disputing Environmental Change in the Drylands . . . . It is edited by two people who know a thing or two about these issues—Roy Behnke and Mike Mortimore—and it has 20 top quality chapters from all over the world, documenting why the term desertification has passed its sell-by date, if it ever had one at all. It is an impressive and timely synthesis . . . .

The myths of desertification have a long history. Ideas of desiccation and desert advance framed colonial science, informed by the narratives of the ‘dust bowl’ in the US. Yet whether from long-term environmental monitoring, areal and satellite photography, ecological modelling or local knowledge and field observation, the standard narratives have been found severely wanting.

‘Unfortunately this accumulated evidence has been ignored, and the narratives of desertification persist. . . .

‘In the 1970s, influenced by the new mathematics of complexity, ecologists such as Bob May argued that stability not an expected feature of ecosystems, even under deterministic conditions. In the context of African rangelands, Jim Ellis and team in Turkana—notably through the classic 1988 paper—contributed to an understanding of ecosystems not at equilibrium where density-independent factors (rainfall/drought/flood/snow) meant that animal populations were not at equilibrium, and different management regimes needed to apply.

‘Challenges to desertification myths, and simplistic equilibrium approaches to rangeland dynamics based on Clementsian succession ecology, have long been made. . . . A new paradigm for African rangeland management was born. . . .

Why is it that, even when scientific evidence is incontrovertible, then shifts in policy discourse and practice doesn’t happen?

Read the full story: ILRI

Published by

Willem Van Cotthem

Honorary Professor of Botany, University of Ghent (Belgium). Scientific Consultant for Desertification and Sustainable Development.