Geoscience Reference
In-Depth Information
Desertiication
than ever, causing the loss of a number of
towns and villages. Forests in the western
United States, where the area burned each
year has increased dramatically in the past
two decades, are particularly susceptible to
fire. Recent examples of large fires in de-
veloped areas, all in 2009, include fires in
Greece (which burned 21,250 hectares, or
52,500 acres); the Station Fire in Los An-
geles County (56,650 hectares, or 140,000
acres); and the Black Saturday bushfires in
southern Australia (445,000 hectares, or
1,100,000 acres), which killed 173 people.
All these fires damaged or destroyed many
buildings.
Other forested regions that will be sus-
ceptible to large fires in the future include
parts of South Africa, much of Europe,
the Mediterranean rim, and the Amazon
Basin.
These large fires create serious problems
for wildlife and are major sources of pol-
lution, as post-fire rains cause extensive
erosion on ash-covered slopes, polluting
nearby streams and rivers. All fires in na-
ture, plus those created by human beings
in the deforestation process, provide a CO
2
contribution equal to 50% of the CO
2
con-
tribution from fossil fuels. In the Pacific
Northwest and other parts of the world as
well, brush and dead trees are often cleared
from forests to reduce the potential for fu-
ture fires. Unfortunately this reduces the
carbon sequestering effect of forests and
thus effectively increases the CO
2
content
of the atmosphere.
Western civilization, its wealth and power
symbolized by the busy bulldozer, can't
seem to resist the temptation to confront
nature in places where we arguably don't
belong. Deserts are such places: only a
small number of people can eke out a liv-
ing in deserts unless they are supported by
massive technology such as dams and ir-
rigation systems. In his topic
Cadillac Des-
ert
, Marc Reisner recounts the settling of
the deserts in the western United States, a
process leading to the current situation, in
which large amounts of money are infused
into these regions, resulting in dwindling
water supplies and increasing conflicts be-
tween water users.
Desertification—the deterioration of
land and the reduction of vegetation and
soil in arid areas—results from climatic
variations as well as human activities such
as those described by Reisner. Desertifica-
tion is expected to spread in the Ameri-
can West and likewise in Australia. The
Mozambique coastal zone in East Africa
is at particularly high risk for desertifi-
cation, in part because local inhabitants
have destroyed mangrove forests along the
shoreline. Desertification is also a strong
possibility in a broad sub-Saharan band
across the African continent. Over a num-
ber of centuries 28% of China has been af-
fected by desertification, much of it caused
by deforestation and overgrazing. Chang-
ing weather patterns, which contribute to
