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Connections Between Climate and Desertification

Published online by Cambridge University Press:  24 August 2009

F. Kenneth Hare
F. Kenneth Hare
Affiliation:
University Professor and Director, Institute for Environmental Studies, University of Toronto, Toronto, Ontario, Canada; formerly President, Royal Meteorological Society and Director-General of Research Coordination, Department of the Environment, Canada; sometime Master of Birkbeck College, University of London.
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Extract

The widespread fear that the Earth's deserts are spreading was reawakened by the major 1968–73 drought in Sahelian West Africa, Sudan, Ethiopia, and parts of Kenya. There appears, however, to be no firm evidence that a permanent desiccation of the arid zone is in progress. Instead, the evidence suggests that ‘desertification’—defined as the spread of desert surfaces, regardless of cause—results more immediately from faulty land-use practices and their interaction with prolonged natural drought episodes.

Desertification appears to be a process of degradation of grassland, scrub, or savanna, ecosystems under the impact of overstocking or excessive cultivation. During periods of desiccation there is widespread destruction of perennial vegetation, compaction of soil (especially near watering places), and deflation of fine materials (wind erosion).

Such surfaces are lighter-coloured than native vegetation, and reflect more sunlight. This may enhance atmospheric subsidence, and hence intensify drought. Loss of surface organic litter may also act as a positive feedback for drought.

Prediction of such episodes is at least some years away, but three possibilities exist for such prediction: use of cyclical variations, where present; time-lagged teleconnections; and general circulation modelling.

Reduced infiltration in some arid areas, combined with excessive withdrawals in others, have lowered both shallow alluvial and deep fossil ground-water tables—in some areas to the point at which stock water-supply can no longer be maintained.

Type
Main Papers
Information
Environmental Conservation , Volume 4 , Issue 2 , Summer 1977 , pp. 81 - 90
Copyright
Copyright © Foundation for Environmental Conservation 1977

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