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Table 3: Extent of soil degradation within the area affected by land degradation.
Land use Total area within Area affected by Area affected by
Category drylands land degradation soil degradation
(million ha) (million ha) (million ha)
Irrigated
cropland 145 43 4
Rainfed
cropland 457 216 216
Rangeland 4,556 3,333 757
Total 5,158 3,592 1,016
Data source: UNEP (1991)
The preponderance of evidence collected thus far confirms that land degradation is
a man-made problem. It is not a new phenomenon and has been in existence since
the dawn of agriculture (Barrow, 1991 and Hillel, 1991). What is new is the intensity
of degradation in recent times. For example, Rozanov et al. (1990) showed that the
soils of the world lost 25.3 million tons of humus per year on average since agriculture
began some 10,000 years ago. However, average humus losses were 300 million
tons per year in the last 300 years and 760 million tons in the past 50 years. So
they appear to accompany the growth of population, expansion of croplands,
destruction of vegetation, global warming and emergence of yield-enhancing technologies.
In essence, the last 50 years have been a saga of economic growth and
ecological losses, both unevenly distributed. The inherently disadvantaged dryland
environments have suffered relatively more ecological damage and less economic
gain. Although the causes of land degradation are well-documented, it continues to
spread at a rate of 6 million ha per annum (FAO/UNEP, 1984).
Dregne and Chou (1992) estimate that nearly 1,860 million ha, or little more than
half of the desertified area world-wide, requires rehabilitation. The cost of rehabilitation
over a 20-year period was calculated to be about US$ 213 billions. If not rehabilitated,
Dregne and Chou figure that the income foregone (over a 20-year period)
could equal a staggering US $ 564 billions. Razanov et al. (1990) believe that the
annual loss through degradation (6 million ha) is practically irreversible. The reliability
of these statistics has been a subject of debate (Mainguet, 1994, and Thomas and
Middleton, 1996). Although the accuracy of the numbers may be argued, the magnitude
of the problem and its potentially negative impact on sustainable development
is beyond question. In fact, if present trends are any indication, it is anticipated that
the severity of desertification will increase as the pressure of population on land
mounts, becoming all the more intense in developing countries.
Statistics on disasters resulting from creeping events are difficult to come by. First of
all, the consequences of such processes are coped with in many different ways. In
the case of desertification, for instance, strategies are applied that reduce population
pressure through permanent out-migration, migrant labour and remittances.
Although often associated with personal tragedies, this uprooting of societies rarely
Essay
Degradation has a profound
impact on sustainable development.
If present trends are
anything to go by, the severity
of desertification will increase
as the pressure on land
mounts, becoming all the more
intense in developing countries.
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