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Lake Chad: A conspiracy of climate change and crops
Straddling the borders of Chad, Niger and Cameroon in West Africa,
Lake Chad has been a source of freshwater for irrigation projects
in all these countries. Maps drawn from a series of satellite images
show a dramatic decrease in the size of the lake over the past 30
years. Since 1963, the lake has shrunk to nearly a twentieth of
its original size, due both to climatic changes and to high demands
for agricultural water. Since 1963, the surface area of Lake Chad
has decreased from approximately 25 000 km2 to 1 350
km2 (Scientific American, 2001).
- Between June 1966 and January 1973, the surface area of Lake
Chad shrunk from 22 772 km2 to 15 400 km2.
- In 1982, the lake's surface area was estimated to be about 2
276 km2. In February 1994, Meteosat images were used
to measure it at just 1 756 km2 .
- Between 1953 and 1979, irrigation had only a modest impact on
the Lake Chad ecosystem. Between 1983 and 1994, however, irrigation
water use increased four-fold.
- About 50% of the decrease in the lake's size since the 1960s
is attributed to human water use, with the remainder attributed
to shifting climate patterns.
- Invasive plant species currently cover about 50% of the remaining
surface of Lake Chad.
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Research carried out over the past 40 years indicates that the
main factors in the shrinking of the lake have been:
- Major overgrazing in the region (Coe and Foley, 2001), resulting
in the loss of vegetation and serious deforestation, contributing
to a drier climate;
- Large and unsustainable irrigation projects built by Niger,
Nigeria, Cameroon and Chad, which have diverted water from both
the lake and the Chari and Logone rivers.
The changes in the lake have contributed to local lack of water,
crop failures, livestock deaths, collapsed fisheries, soil salinity,
and increasing poverty throughout the region.
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