Desertification, Drought, and Surface Vegetation: An Example from the West African Sahel

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Many assumptions have been made about the nature and character of desertification in West Africa. This paper examines the history of this issue, reviews the current state of our knowledge concerning the meteorological aspects of desertification, and presents the results of a select group of analyses related to this question. The common notion of desertification is of an advancing “desert,” a generally irreversible anthropogenic process. This process has been linked to increased surface albedo, increased dust generation, and reduced productivity of the land. This study demonstrates that there has been no progressive change of either the Saharan boundary or vegetation cover in the Sahel during the last 16 years, nor has there been a systematic reduction of “productivity” as assessed by the water-use efficiency of the vegetation cover. While it also showed little change in surface albedo during the years analyzed, this study suggests that a change in albedo of up to 0.10% since the 1950s is conceivable.

*Department of Meteorology, The Florida State University, Tallahassee, Florida.

+NASA, Laboratory for Terrestrial Physics, Goddard Space Right Center, Greenbelt, Maryland.

#Current affiliation: National Oceanic and Atmospheric Administration-National Environmental Satellite, Data and Information Service, Washington, D.C.

Corresponding author address: Prof. S. E. Nicholson, Department of Meteorology, The Florida State University, Tallahassee, FL 32306-3034.

Many assumptions have been made about the nature and character of desertification in West Africa. This paper examines the history of this issue, reviews the current state of our knowledge concerning the meteorological aspects of desertification, and presents the results of a select group of analyses related to this question. The common notion of desertification is of an advancing “desert,” a generally irreversible anthropogenic process. This process has been linked to increased surface albedo, increased dust generation, and reduced productivity of the land. This study demonstrates that there has been no progressive change of either the Saharan boundary or vegetation cover in the Sahel during the last 16 years, nor has there been a systematic reduction of “productivity” as assessed by the water-use efficiency of the vegetation cover. While it also showed little change in surface albedo during the years analyzed, this study suggests that a change in albedo of up to 0.10% since the 1950s is conceivable.

*Department of Meteorology, The Florida State University, Tallahassee, Florida.

+NASA, Laboratory for Terrestrial Physics, Goddard Space Right Center, Greenbelt, Maryland.

#Current affiliation: National Oceanic and Atmospheric Administration-National Environmental Satellite, Data and Information Service, Washington, D.C.

Corresponding author address: Prof. S. E. Nicholson, Department of Meteorology, The Florida State University, Tallahassee, FL 32306-3034.
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