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even argued that drought was a human construct arising from destructive forms of
land use - an odd way to ignore the reality of prolonged below-average rainfall.
As time passed, the UNEP definition stressing 'adverse human impact' was widely
adopted, to the dismay of many African nations, who were all too aware of the adverse
impact of droughts and so were able to lobby effectively at the 1992 Rio Earth Summit
for a change in definition and for the creation of a future international convention to
deal with desertification. The African environment ministers had become frustrated by
the lack of any substantive progress in dealing with desertification in Africa and there-
fore met in November 1991 in Abidjan in order to prepare a common position paper
for Africa to present at the 1992 Earth Summit (Kassas, 1995b ; Williams, 2002b ).
They were unanimous in requesting that a new convention to combat desertification
be a specific recommendation for inclusion in Agenda 21 , and with the backing of
many other countries who were facing similar problems, including China (China's
Agenda 21, 1994; Ci Longjun, 1998 ), they were successful. Chapter 12 of Agenda 21
is called 'Managing fragile ecosystems: combating desertification and drought' and
is a lucid analysis of the causes and consequences of desertification, with some very
practical action plans for use at national and international scales (UNCED, 1992 ).
The great African droughts of the 1930s and the 1970s triggered considerable
speculation as to the respective role of climatic fluctuations and human influences
on land degradation along the margins of the Sahara. Many observers blamed the
destruction of the vegetation and the mobilisation of hitherto fixed and stable dunes
entirely on humanmismanagement in the formof overgrazing and the clearing of forest
and woodland for arable land. Some even argued that the Sahara Desert was itself at
least in part a product of adverse human impact. Phrases like 'desert encroachment'
or 'the advancing desert' were bandied about with more enthusiasm than accuracy
(see also Grove, 1974 , for an incisive and elegant critique of such views in regard to
Africa). Such sensationalism took no account of the long geological history of the
deserts, nor of the fact that the deserts long predate human origins (see Chapters 3 ,
17 and 18 ). While the deserts may have helped shape the prehistoric cultures of the
occasional desert dwellers, there is scant evidence that the reverse applies, at least
until more recent times.
Political and scientific awareness of desertification was enhanced by the publication
of two quite different editions of the UNEP World Atlas of Desertification (UNEP,
1992a ; UNEP, 1997 ). One of the great merits of both atlases lies in the detailed
case studies prepared by local specialists drawn from throughout the desert world,
which diagnose the local and regional causes of land degradation and identify a
variety of solutions. In the five years between the publication of the first and second
editions of these two very useful atlases, there was already a much clearer scientific
appreciation of the nature and causes of climatic variations, including global floods
and droughts. This is very clearly reflected in the thoughtful editorial discussion of
climatic fluctuations by Middleton and Thomas in the second edition (UNEP, 1997 ).
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