Chapter 5: Natural Systems
Under Stress
Daniel Burton
Geoff Koegler
Overview
• Chapter Summary
• Fact Check
Natural Systems Under Stress
“Mercilessly expanding human demands
are putting stresses on forests,
rangelands, and fisheries that they cannot
withstand. We are also destroying many of
the plant and animal species with which
we share the planet”.
Shrinking Forests
• Effects of Deforestation
• Pressures on Deforestation
• The importance of the world’s forests
Losing Soil
• Topsoil and soil erosion
• Dust Bowl Examples
• Global effects of Dust Bowls
Grassland to Desert
• Grass-based livestock economies
• Livestock Vs. Carrying Capacity
• Land Degradation
Advancing Deserts
• Desertification
• Stages of Desertification
• Effects of Desertification
Collapsing Fisheries
• Demand increase for seafood
• Effects of over-fishing
• Canadian Cod
• EU Solution
• Dead Zones
Disappearing Plants and Animals
• The sixth great extinction
• Habitat Destruction
• Bird Population
• Bee Population
• Non-native Species
Fact Check: Natural Systems Under
Stress
• Loss of Forests
• Desertification
• Collapsing Fisheries
• Extinction
Loss of Forests
• Brown: Forests make up 4 billion
World-Wide Forests
4100
4080
4060
Hectares (millions)
•
hectares today, down from 5 billion in
1900
U.N. FAO:
4040
4020
4000
3980
3960
3940
1998
1999
2000
2001
2002
Year
2003
2004
2005
2006
Loss of Forests
• Forest cover is growing in developed
countries
(U.N. FAO)
Loss of Forests
• Forest cover is declining in developing
countries
(U.N. FAO)
Loss of Forests
• The Amazon
– Brown: Brazil has lost 20% of the Amazon
since 1970
– U.N. FAO:
% of 1970 Cover Remaining
120
100
%
80
60
40
20
0
1965
1970
1975
1980
1985
Year
1990
1995
2000
2005
Desertification
• Brown: Sahara Desert is
growing rapidly
– Nigeria: losing 351,000
hectares of land each
year
• Center for International
Earth Science
Information:
– Lack of rain is the largest
cause
Desertification
• Brown: China losing 3,600 square km per year,
up from 2,100 in the 1970s and 80s,
– Resulted in the loss of over 24,000 villages during the
past 50 years
• China is indeed losing
this much land (China
Environmental Science
Presses)
– Disputes as to how many
villages have been lost (4,000
according to the Boston Globe)
Collapse of Fisheries
• Brown: World-wide fish catch at a historic
high of 96 million tons in 2000, 75% of
fisheries are over fished
• U.N. FAO:
• 80% of Fisheries
are over fished
(Oceana)
Collapse of Fisheries
• Brown: Canadian Cod Fishery collapsed in
1990 as a result of overfishing
• U.N. FAO:
Collapse of Fisheries
• Brown: Chesapeake Bay oyster catches
have decreased rapidly
• Chesapeake Bay Program:
Collapse of Fisheries
• Brown: Gulf of Mexico “Dead Zone” (size of New
•
Jersey) kill fish due to algae blooms
Sierra Club: 4,565 square miles, roughly the size
of Connecticut
(NASA)
Extinction
• Brown: An alarming amount of species are
vulnerable or in immediate danger of
extinction
– 12% of birds
– 20% of mammals
– 39% of fish
• Conservation
International Study
– 36% of land mammals
– 61% of ocean mammals
Summary
• Lester Brown clearly depicts how several
of earth’s natural systems are under stress
• Uses accurate and interesting information
to convey issues regarding:
– Loss of Forests
– Desertification
– Collapsing Fisheries
– Extinction
“On the plus side, we now have more
information on the state of the earth and
the life on it than ever before. While
knowledge is not a substitute for action, it
is a prerequisite for saving the earth’s
natural systems- and the civilization that
they support”.
Questions?
References
•
Chesapeake Bay Program. (2008). Oysters: Commercial Harvest. Retrieved October 25, 2008, from
http://www.chesapeakebay.net/status_oysterharvest.aspx?menuitem=19819
•
Compton, T, Dregne, H, Newcomb, W. (1991). Expansion and Contraction of the Sahara Desert from 1980 to 1990. Center for International Earth
Science Information Network Retrieved October 25, 2008, from http://www.ciesin.org/docs/005-319/005-319.html
•
Datong, Ning. (1989). An Assessment of the Economic Losses Resulting from Various Forms of Environmental Degradation in China. China
Environmental Science Presses Retrieved October 25, 2008, from http://www.library.utoronto.ca/pcs/state/chinaeco/desert.htm
•
Food and Agriculture Organization of the United Nations. (2008). Fisheries and Aquaculture Department. Retrieved October 25, 2008, from
http://www.fao.org/fishery/en
•
Food and Agriculture Organization of the United Nations. (2008). Forestry. Retrieved October 25, 2008, from http://www.fao.org/forestry/home/en/
•
NASA. (2007). Mississippi Dead Zone. Retrieved October 25, 2008, from http://www.nasa.gov/vision/earth/environment/dead_zone.html
•
Oceana. Over 80% of Fisheries Overfished: Report. Retrieved October 25, 2008, from
http://www.oceana.org/fileadmin/oceana/uploads/dirty_fishing/cut_the_bait/AFP_27_may_08.doc
•
Pocha, J. (September 18, 2006). China’s Dangerous Dustbowl. Boston Globe. Retrieved October 25, 2008, from
http://www.boston.com/yourlife/health/other/articles/2006/09/18/chinas_dangerous_dustbowl/
•
Roach, J. (October 5, 2004). Bee Decline May Spell End of Some Fruits, Vegetables. National Geographic News. Retrieved October 25, 2008, from
http://news.nationalgeographic.com/news/2004/10/1005_041005_honeybees.html
•
Sierra Club. (2008). The Dead Zone in the Gulf of Mexico. Retrieved October 25, 2008, from
http://www.sierraclub.org/cleanwater/waterquality/deadzone.asp
•
Weiss, K. (October 6, 2008). Many Wild Animals Face Extinction, Survey Finds. Chicago Tribune. Retrieved October 25, 2008, from
http://www.chicagotribune.com/news/nationworld/chi-extinct-mammalsoct07,0,1044472.story