Download Ch. 2: The Changing Global Environment

Ch. 2: The Changing Global Environment
Globalization and Diversity Rowntree, Lewis, Price, Wyckoff As
modified by Joe Naumann, UMSL
Learning Objectives
• Learn about the basics of Earth’s environmental
systems to prepare for later chapters
• Understand the following concepts, models,
and terms
- Greenhouse Effect
- Anthropogenic
- Green Revolution
- Bioregion
- Prairie
- Climograph
- Steppe
- Desertification
- Subduction Zone
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Global Climates: An Uncertain Forecast
• Human settlement and food production
are closely linked to local patterns of
weather and climate
– People in different parts of the world adapt to
weather and climate in different ways
– Climate links us together in our globalized
economy
• Opportunities for some
• Hardship for others
• Challenges in growing food
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Four Laws of Ecology Apply
• Everything is connected
• Everything goes somewhere
• Nature knows best
• There’s no such thing as a free lunch
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World Climate Regions
• Weather: short-term, day-to-day expression of
atmospheric processes
• Climate: long-term, average conditions
– Usually at least 30 years of daily weather data
(temperatures and precipitation)
• Climate regions: boundaries drawn around areas
with similar average climate conditions
– Helps us to make inferences about human activities and settlement
• Example: desert hampers agriculture; adequate rainfall, warm
temperatures permit farming
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World Climate
Regions - North & South America
(Fig. 2.3)
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World Climates
Europe, Africa, Asia, Australia
(Fig. 2.3)
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Global Climates, cont.
• Climographs: provide average high and low
temperatures and precipitation for every month in
an entire year – a very useful illustration
– Graph form
•
•
•
•
Average high temperature (upper line)
Average low temperature (lower line)
Sometimes just the daily average for the month is shown
Average precipitation (bars)
• The extremes are not shown.
– Provides “Average Annual Rainfall” figure
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Climograph:
many only show the monthly
average temperature
TERRE HAUTE, INDIANA
30-Year Normals 1971-2000
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100
Average Precipitation
4.5
Average High Temperature
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Degrees (F)
80
70
3.5
60
3
50
2.5
40
2
30
1.5
20
1
10
0.5
Inches
90
Average Low
Temperature
0
0
1
2
3
4
5
6
7
8
9
10
11
12
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Average Annual Precipitation: 40 inches
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Convectional
• Land is heated and
heats the air which
then rises
• Rising air cools &
water vapor
condenses
• When raindrops are
heavy enough to
overcome the
updraft of rising air,
there is precipitation
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Cyclonic/Frontal
• Warmer air is lighter
than cooler air, so
when two air
masses come in
contact, the lighter
one rises above the
cooler one.
• Then there is
cooling,
condensing, and
precipitation
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Orographic
• A moist air mass meets
a mountain range, and it
is forced up and cools.
• Then follows condensing
and precipitation on the
windward side of the
range. The leeward side
receives little or no rain
and has a dry climate.
• On the west coast, the
coastal range and the
Sierra Nevada ranges
demonstrate this.
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Global
Climates, cont.
• Global Warming
– Human activities connected
with economic development
and industrialization affect
the world’s climate
• Anthropogenic (humancaused) pollution
increases the natural
greenhouse effect
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Global Warming
• Causes of Global Warming
– Natural greenhouse effects make the earth
warm enough to support life
– Beginning with Industrial Revolution in Europe
and North America, greenhouse gases have
increased dramatically, mostly from burning
fossil fuels
– Carbon dioxide (CO2); Chlorofluorocarbons
(CFCs); Methane (CH4); Nitrous oxide (N2O)
are the major greenhouse gases
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Global
Warming, cont.
• The Four Major Greenhouse Gases
– Carbon Dioxide (CO2): makes up more than 50%
of anthropogenic greenhouse gases; comes
mainly from burning fossil fuels
– Chlorofluorocarbons (CFCs): about 25% of
human-generated greenhouse gases; come
mainly from aerosol sprays, refrigeration, & air
conditioning – also cause ozone depletion.
– Methane (CH4): about 15%; caused by burning of
vegetation, by-products of cattle & sheep
digestion, leaking natural gas pipelines, and
refineries
– Nitrous oxide (N2O): 5%; caused by agricultural
chemical fertilizers
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Effects of
Global Warming
– Computer models and scientists are coming to
agreement on effects
• Average global temperatures will increase 2 °F to 4
°F by 2030 – more extreme & less predictable
weather
– The same amount of cooling caused the Ice Age
• Major shift in agricultural areas
– Wheat belt could become warmer and drier; lower grain yield
– Canada and Russia could become warmer
– Southern regions of the U.S. and Europe could become warmer and
drier, requiring irrigation
• Rising sea levels as polar ice-caps melt, endangering
low-lying islands around the world, and coastal areas
elsewhere
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How can it be denied?
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Globalization
& Climate Change
• International Debate on Limiting
Greenhouse Gases
– Rio de Janiero Earth Summit (1992)
• First international agreement on global
warming
• 167 countries agreed to reduce their
greenhouse gas emissions by a specific target
date
– U.S., Japan, India, China failed to meet emissions
reductions
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Globalization & Climate Change
– Kyoto Protocol (December
1997)
• 38 industrialized countries
agreed to reduce their
emissions of greenhouse
gases to below 1990 levels
• To take effect, countries
emitting 55% of the world’s
greenhouse gases must
ratify it
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International
Debate - Limit Greenhouse Gases
– Ratification of Kyoto Protocol will be difficult
• Pres. Bush opposes; says complying will
damage U.S. economy
– Large developing countries (India, China) are not yet
bound to reduce greenhouse gases, and would have
an advantage
– Pres. Bush believes more study is needed to support
a link between human activities and global warming
• Bush administration in 2004 only admitted that
there “might be a connection.” World view: the
USA has been “dragging its feet” on global
warming.
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Ratification of
Kyoto Protocol will be difficult
– Tensions between developed and lessdeveloped countries
• Unrestricted emissions in developed world
created global warming problem; developed
countries emit more than 50% of the world’s
greenhouse gases
• LDCs believe MDCs should curb their
emissions, and help LDCs limit their emissions
• LDCs fear that ratifying Kyoto Protocol will limit
their development
• LDCs’ emissions are currently relatively low
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Human Impacts
on Plants and Animals
– Earth is unique because of the rich diversity of plants
and animals – becoming less diverse!
– Vegetation is the “green glue” that binds together
Earth’s life and atmosphere
• Vegetation is both a product of and an influence on climate,
geology and hydrology
– Humans play a big part in this interaction
• Domestication of plants, animals
• Endangerment of plants, animals
• Changed natural pattern of vegetation on the land
– Bioregion (Biome): an assemblage of local plants and
animals covering a large area (e.g., tropical rainforest
or grassland)
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Bioregions:
North &
South
America
(Fig. 2.5)
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Bioregions: Europe,
Africa, Asia, Australia (Fig. 2.5)
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Globalization of Nature
• Tropical Forests and Savannas
–
–
–
–
Mostly found in equatorial climate zones
Covers around 7% of the world’s land area
Three-layered canopy
As one moves poleward, distinct dry season forms and tropical
forest becomes more open
– Farther poleward, grassland and savanna replace forest
• Deforestation in the Tropics
– Annually, an area of tropical forest the size of Wisconsin is
denuded
• Land cleared for wood sale, cattle grazing, and settlement
purposes – forests may not be able to regenerate if too
much is cut down
• Native peoples who live there lose the most
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Deserts and Grasslands
– These are large areas of arid and semi-arid climate that lie
poleward (north and south) of the tropics
– Comprise one-third of the Earth’s land surface
• Desert: areas receive less than 10 inches of rainfall a year
• Prairie: North American grassland
• Steppe: shorter, less dense grassland found in Russia and
Southwest Asia
– Desertification: the spread of desert-like conditions
• Caused by poor agricultural practices on marginal land,
overgrazing, build-up of salts in soil from irrigation & planting in
the “fallow” year
• UN estimates that 60% of the world’s rangelands are threatened
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by desertification
Temperate Forests
– Large tracts of forests found in middle and high latitudes
(nearer the poles)
– Two major tree types dominate
• Conifers or evergreens (pine, spruce, fir)
• Deciduous trees that lose leaves in winter (hardwoods include
elm, maple, beech, and many others)
– In many regions, these forests have been cleared for
agricultural purposes
– Commercial logging interests place global pressure on
forests
• Clear cutting versus selective cutting controversy
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Food Resources
• Food production must double by 2025 to keep pace
with expected human population growth rates
– Every minute: 170 people are born, and 10 acres of
existing cropland are lost
• The Green Revolution: most work was with
grains
– Has increased global food production since the 1950s
– Changes include the following:
• Shift from mixed crops to monocrops – single crop fields – of highyield, genetically altered seeds
• Intensive application of water, fertilizer, pesticides
• Intensification of farming through reduction in fallow periods, or
field-resting time between planting seasonal crops
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Green Revolution
– Second stage of Green Revolution since 1970s
• New types of fast-growing wheat and rice specifically bred for
tropical & subtropical climates
• With irrigation, fertilizers & pesticides, farmers can grow 2 or 3
crops each year instead of just one
• India doubled its food production between 1970-1992
– Problems associated with Green Revolution
• Heavy use of fossil fuels makes Green Revolution agriculture
more vulnerable to oil price fluctuations
• Environmental damage
• Social costs, especially associated with the higher cost of this
approach
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Food Resources
• Problems and Projections
– Local and regional problems are usually responsible for
food unavailability
• Poverty and civil unrest at local levels impede food distribution
– Political problems are usually more responsible for food
shortages as compared to natural events
• Food distribution is highly politicized
– Globalization is causing a worldwide change in food
preferences
• Implications of shifting from vegetarian to meat-based diet
– Africa and South Asia are most threatened by food
shortages
• UN predicts that by 2010, almost 200 million in South Africa will
suffer from chronic undernourishment
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Continental Drift
The “solid earth” isn’t so solid
• Appears to be generated by heat-sustained
convection cells in the interior (particularly the
asthenosphere which is not solid)
– Movement occurs where plate boundaries abut
– Divergence – spreading along mid-ocean ridges
which lie above and upwelling in the cell
– Convergence (subduction) – colliding plates over
the downward portion of a convection cell
– Ring of Fire – largely an area of subduction
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Movement
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Tectonic Plates
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Conclusions
– Some environmental change is natural, some is
anthropogenic
– Globalization both helps and hinders world
environmental problems
• World’s nation-states more willing to sign
environmental treaties (whaling, ocean pollution,
fisheries, wildlife protection)
• But superheated global economic activity aggravates
global environmental problems
• This theme reappears throughout the text
End of Chapter 2
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