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[Livingontheland] Civilization's foundation eroding
- From: "Tradingpost" <tradingpost@lobo.net>
- To: livingontheland@lists.ibiblio.org
- Subject: [Livingontheland] Civilization's foundation eroding
- Date: Tue, 05 Oct 2010 21:18:04 -0600
Civilization's foundation eroding
by Lester Brown Published Sep 28 2010 by Earth Policy Institute
http://www.earth-policy.org/index.php?/book_bytes/2010/pb4ch02_ss2
The thin layer of topsoil that covers the planets land surface is the
foundation of civilization. This soil, typically 6 inches or so deep, was
formed over long stretches of geological time as new soil formation exceeded
the natural rate of erosion. But sometime within the last century, as human
and livestock populations expanded, soil erosion began to exceed new soil
formation over large areas.
This is not new. In 1938, Walter Lowdermilk, a senior official in the Soil
Conservation Service of the U.S. Department of Agriculture, traveled abroad
to look at lands that had been cultivated for thousands of years, seeking to
learn how these older civilizations had coped with soil erosion. He found
that some had managed their land well, maintaining its fertility over long
stretches of history, and were thriving. Others had failed to do so and left
only remnants of their illustrious pasts.
In a section of his report entitled The Hundred Dead Cities, he described a
site in northern Syria, near Aleppo, where ancient buildings were still
standing in stark isolated relief, but they were on bare rock. During the
seventh century, the thriving region had been invaded, initially by a Persian
army and later by nomads out of the Arabian Desert. In the process, soil and
water conservation practices used for centuries were abandoned. Lowdermilk
noted, Here erosion had done its worst .if the soils had remained, even
though the cities were destroyed and the populations dispersed, the area
might be re-peopled again and the cities rebuilt, but now that the soils are
gone, all is gone.
Wind and water erosion take a toll. The latter can be seen in the silting of
reservoirs and in satellite photographs of muddy, silt-laden rivers flowing
into the sea. Pakistans two large reservoirs, Mangla and Tarbela, which
store Indus River water for the countrys vast irrigation network, are losing
roughly 1 percent of their storage capacity each year as they fill with silt
from deforested watersheds.
Ethiopia, a mountainous country with highly erodible soils, is losing close
to 2 billion tons of topsoil a year, washed away by rain. This is one reason
Ethiopia always seems to be on the verge of famine, never able to accumulate
enough grain reserves to provide meaningful food security.
Soil erosion from the deterioration of grasslands is widespread. The worlds
steadily growing herds of cattle and flocks of sheep and goats forage on the
two fifths of the earths land surface that is too dry, too steeply sloping,
or not fertile enough to sustain crop production. This area supports most of
the worlds 3.3 billion cattle, sheep, and goats, all ruminants with complex
digestive systems that enable them to digest roughage, converting it into
beef, mutton, and milk.
An estimated 200 million people make their living as pastoralists, tending
cattle, sheep, and goats. Since most land is held in common in pastoral
societies, overgrazing is difficult to control. As a result, half of the
worlds grasslands are degraded. The problem is highly visible throughout
Africa, the Middle East, Central Asia, and northwest China, where the growth
in livestock numbers tracks that in human numbers. In 1950, Africa was home
to 227 million people and 273 million livestock. By 2007, there were 965
million people and 824 million livestock.
Nigeria, Africas most populous country, is losing 351,000 hectares (867,000
acres) of rangeland and cropland to desertification each year. While
Nigerias human population was growing from 37 million in 1950 to 148 million
in 2007, a fourfold expansion, its livestock population grew from roughly 6
million to 102 million, a 17-fold jump. With the forage needs of Nigerias 16
million cattle and 86 million sheep and goats exceeding the sustainable yield
of grasslands, the northern part of the country is slowly turning to desert.
If Nigeria continues toward its projected 289 million people by 2050, the
deterioration will only accelerate.
Iran, with 73 million people, illustrates the pressures facing the Middle
East. With 8 million cattle and 79 million sheep and goatsthe source of wool
for its fabled rug-making industryIrans rangelands are deteriorating from
overstocking. In the southeastern province of Sistan-Balochistan, sand storms
have buried 124 villages, forcing their abandonment. Drifting sands have
covered grazing areasstarving livestock and depriving villagers of their
livelihood.
Neighboring Afghanistan is faced with a similar situation. The Registan
Desert is migrating westward, encroaching on agricultural areas. A U.N.
Environment Programme (UNEP) team reports that up to 100 villages have been
submerged by windblown dust and sand. In the countrys northwest, sand dunes
are moving onto agricultural land in the upper reaches of the Amu Darya
basin, their path cleared by the loss of stabilizing vegetation from firewood
gathering and overgrazing. The UNEP team observed sand dunes 15 meters high
blocking roads, forcing residents to establish new routes.
China faces similarly difficult challenges. After the economic reforms in
1978 that shifted the responsibility for farming from large state-organized
production teams to farm families, Chinas cattle, sheep, and goat
populations spiraled upward. While the United States, a country with
comparable grazing capacity, has 97 million cattle, China has a slightly
smaller herd of 82 million. But while the United States has only 9 million
sheep and goats, China has 284 million. Concentrated in Chinas western and
northern provinces, sheep and goats are destroying the lands protective
vegetation. The wind then does the rest, removing the soil and converting
productive rangeland into desert.
Chinas desertification may be the worst in the world. Wang Tao, one of the
worlds leading desert scholars, reports that from 1950 to 1975 an average of
600 square miles turned to desert each year. By centurys end, nearly 1,400
square miles (3,600 square kilometers) were going to desert annually. Over
the last half-century, some 24,000 villages in northern and western China
have been entirely or partly abandoned as a result of being overrun by
drifting sand.
China is now at war. It is not invading armies that are claiming its
territory, but expanding deserts. Old deserts are advancing and new ones are
forming like guerrilla forces striking unexpectedly, forcing Beijing to fight
on several fronts.
Soil erosion often results from the demand-driven expansion of cultivation
onto marginal land. Over the last century or so there were massive cropland
expansions in two countriesthe United States and the Soviet Unionand both
ended in disaster.
During the late nineteenth century, millions of Americans pushed westward,
homesteading on the Great Plains, plowing vast areas of grassland to produce
wheat. Much of this landhighly erodible when plowedshould have remained in
grass. This overexpansion culminated in the 1930s Dust Bowl, a traumatic
period chronicled in John Steinbecks novel The Grapes of Wrath. In a crash
program to save its soils, the United States returned large areas of eroded
cropland to grass, adopted strip-cropping, and planted thousands of miles of
tree shelterbelts.
The second major expansion came in the Soviet Union beginning in the
mid-1950s. In an all-out effort to expand grain production, the Soviets
plowed an area of grassland larger than the wheat area of Australia and
Canada combined. The result, as Soviet agronomists had predicted, was an
ecological disasteranother Dust Bowl. Kazakhstan, where the plowing was
concentrated, has abandoned 40 percent of its grainland since 1980. On the
remaining cultivated land, the wheat yield per acre is one sixth of that in
France, Western Europes leading wheat producer.
A third massive cropland expansion is now taking place in the Brazilian
Amazon Basin and in the cerrado, a savannah-like region bordering the basin
on its south side. Land in the cerrado, like that in the U.S. and Soviet
expansion, is vulnerable to soil erosion. This cropland expansion is pushing
cattle ranchers into the Amazon forests, where ecologists are convinced that
continuing to clear the area of trees will end in disaster. Reporter Geoffrey
Lean, summarizing the findings of a 2006 Brazilian scientific symposium in
Londons Independent, notes that the alternative to a rainforest in the
Amazon would be dry savannah at best, desert at worst.
Civilization depends on fertile soils. Ultimately, the health of the people
cannot be separated from the health of the land. Conserving and rebuilding
soils will be covered in the next Plan B 4.0 Book Byte.
Adapted from Chapter 2, Population Pressure: Land and Water in Lester R.
Brown, Plan B 4.0: Mobilizing to Save Civilization (New York: W.W. Norton &
Company, 2009), available on-line at www.earth-policy.org/index.php?/books/pb4
- [Livingontheland] Civilization's foundation eroding, Tradingpost, 10/05/2010
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