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June 11, 2008—Satellite images from 1972 (left) and 2007 (right) show water-level decline in Lake Chad, once the world's sixth largest.
At the junction of Nigeria, Niger, Chad, and Cameroon, the lake is now one-tenth its former size, due to declining rainfall and diversion of water for human use.
The images are part of Africa: Atlas of Our Changing Environment, a new UN book unveiled today to illustrate how climate change is affecting the continent.
"It is an indication of how serious the situation has become," said Achim Steiner, the agency's executive director, at a meeting in Johannesburg, South Africa.
Africa's most populous urban area, Cairo, Egypt, is shown in 1972 (left) and 2005 (right).
An exploding population has driven the city's expansion, encroaching on much of the precious arable land surrounding the Nile River, according to a UN atlas released June 11, 2008.
A survey published this week by the conservation organization WWF put Egypt, Libya, and Algeria at the head of a list of African nations already living beyond their ecological means.
1978 (left) and 2004 satellite images show the roughly 500-square-kilometer (190-square-mile) reservoir formed by the Manantali Dam in Mali.
Below the dam, loss of the annual flood cycles have reduced agriculture substantially, according to a UN atlas released on June 11, 2008.
The depletion of Guinea's resource-rich coastal zone is illustrated in satellite images from 1975 (left) and 2007.
The population of the Kaloum Peninsula (lower left in both images) tripled between 1963 and 1996, according to a UN atlas released June 11, 2008.
Guinea's coastal zone is home to one-fourth of West Africa's mangroves. But spreading cities are destroying the trees, which help keep shorelines stable and serve as nurseries for fish.
Mali's Lake Faguibine (top in both images) virtually disappeared between 1974 (left) and 2006.
The lake's water levels have varied widely over the last hundred years. But an extended dry period in the 1980s caused the lake to disappear completely in the 1990s, according to a UN atlas released June 11, 2008.
The lake has not been able to recover, despite normal rainfall in recent years, according to the atlas.
Tanzania's Mount Kilimanjaro has seen dramatic glacial retreat between 1976 (left) and 2006.
The mountaintop glacial area has decreased 80 percent since the early 20th century, says a UN atlas released on June 11, 2008.
Although glaciers are melting around the world as temperatures rise, Kilimanjaro's ice is likely melting because of decreasing precipitation, the report says. The melting ice, however, provides little relief to lower areas, because it evaporates too quickly, the atlas adds.
The drier conditions are leading to increased burning. "The upper limit of the forest zone has descended significantly, as nearly 15 per cent of Kilimanjaro's forest cover has been destroyed by fire since 1976," the atlas says.
(Related story: Kilimanjaro's Glaciers May Last Longer Than Predicted [May 1, 2007])
In 1973, Namibia's Walvis Bay salt evaporation ponds were still relatively small (pictured on the left as red and blue rectangles in the centre of the lagoon), says a UN atlas released on June 11, 2008.
The pondswhich produce more than 400 thousand metric tons of high-quality salt each yearhave grown to cover nearly the entire lagoon (as the 2005 satellite image on the right shows).
The bay's tidal channels, mudflats, and sandbanks support roughly 150,000 birds, including the African black oystercatcher, lesser and greater flamingo, chestnut-banded plover, and blacknecked grebe, according to the atlas.
source: National Geographic News
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