Download Themes in Regional Geography

Themes in World Regional
Geography
Geo100 - Fall 2003
Julie Hwang
Lecture #3
Outlines
• Environmental Geography
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Landform
Climates
Vegetation
Water resources
Food resources
How is Earth’s surface shaped?
• Jigsaw puzzle fit of South America to Africa
• Mid-Atlantic Ridge
• Himalaya Mountains
Continental Drift
• The continents are in constant movement
resting upon the plates
• Some 250 million years ago, continents
were connected into one single landmass
called Pangaea
• Pangaea was later separated into continents
in the present day
Laurasia
Pangaea
Gondwanaland
225 million years ago
180 million years ago
The present day
65 million years ago
Continental Drift
• So what drives continental drift?
– Exchange of heat energy from the inner Earth
• Described by Plate Tectonics theory
Earth’s interior
• Core
• Mantle
• Crust
Plate Tectonics
(solid)
Plates
(molten)
Plates drift upon the asthenosphere
Plate Tectonics
Plates
Convection cell
Plates move relative to one another driven by convection cell
Plate Tectonics
• Convergent plate boundary
Subduction
zone
Volcanoes
Plate Tectonics – landforms shaped by
convergent plate boundary
Plate Tectonics
• Divergent plate boundary
Rift Valley
Mid-Ocean
Ridge
Plate Tectonics – landforms shaped by
divergent plate boundary
Olduvai Gorge (Tanzania)
Global tectonic plates
Global earthquakes & volcanoes
Plate Tectonics
• Earth is made up of a large number of
geological plates that move slowly across
its surface
• Explains the inner workings of our planet
and many landforms in a global scale
• Gives clues about the world distribution of
earthquakes and volcanoes
What determines climates?
1. Solar Energy
Greenhouse
effect
2. Latitude
3. Arrangement of oceans and
continents
• Land areas heat and cool faster than do
bodies of water
– Continentality
– Maritime climates
4. Pressure & Wind patterns
40° N
20° N
Equator
20° S
40° S
World Climates
Global Pressure Systems
World Precipitation
Climographs
• Horizontal line show
average high and low
temperature in degree
Fahrenheit.
• Vertical bars show
precipitation in inches.
• For an entire year
Köppen climate classification systems
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A - Moist Tropical Climates
B - Dry Climates
C - Humid Middle Latitude Climates
D - Continental Climates
E - Cold Climates
Climate Type (cont.)
• Tropical (A)
– Tropical rain forest (Af, Am)
– Tropical savanna (Aw)
• Dry (B)
– Steppe (BS)
– Desert (BW)
• Temperate – Mild and rainy winter (C)
– Mediterranean (Cs)
– Humid subtropical (Ca)
– Marine west coast (Cb)
Climate Type
• Temperate – Cold and snowy winter (D)
– Humid continental, warm summer (Da)
– Humid continental, cool summer (Db)
– Subarctic (Dc)
• Polar (E)
– Tundra (ET)
– Icecap (EF)
• Highland (H)
World Climate Regions
Global Warming
Increasing earth surface temperature
Causes of Global Warming
• Emission of anthropogenic (human-caused)
greenhouse gases
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Carbon dioxide (CO2)
Chlorofluorocarbons (CFCs)
Methane (CH4)
Nitrous oxide (N2O)
Effects of Global Warming
• Climate changes
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Increase in global temperature
Rise of sea levels
Intensity and frequency of cyclones
Drought and flood
• Shift in major agricultural areas
• Depletion in the earth’s ozone layer (CFCs)
International debate on limiting
greenhouse gases
• Rio de Janiero Earth summit (’92)
– The first legal instrument addressing global
warming was formulated
• Kyoto protocol (’97)
– 38 industrialized countries agree to reduce the
emissions of major greenhouse gases below
1990 levels
Conflict with economic growth
• Fear that controls will constrain business,
slow the economy, and increase the cost of
living
• U.S. more reluctant to comply than other
nations
World Vegetation
Vegetation
• Product of climate, geology, and hydrology
• Influence on climate, geology, and
hydrology
• Human modification (eg. domestication,
agriculture)
• Threatened by global economy
Biome (Bioregion)
• Grouping of the world’s flora and fauna into
a large ecological province or region
• Closely connected with climate regions, but
the linkage has got less clear since
industrialization (eg. irrigation,
domestication)
• Globalization is having an impact on world
bioregions
Vegetation Type
Tropical
Dry,
Temperate
Tropical forest
Savannas
Deserts
Grasslands: Mediterranean, Temperate
Temperate
Temperate Forests: Deciduous, Coniferous
Polar,
Highland
Tundra
Icecap
Vegetation Type (cont.)
• Tropical forests and Savannas
– Mostly found in equatorial climate zones
– Covers around 7% of the world’s land area
• Deserts and Grasslands
– large areas of arid and semi-arid climate that lie
poleward of the tropics
– Comprise one-third of the Earth’s land surface
– Prairie: North American grassland
– Steppe: shorter, less dense grassland found in Russia
and Southwest Asia
Vegetation Type
• Temperate forests
– Large tracts of forests found in middle and high
latitudes
– Two major tree types dominate: Coniferous and
deciduous
– In many regions, these forests have been cleared for
agricultural purposes
World bioregions
Deforestation in the Tropics
• Cutting-off of tropical forests in Africa,
Latin America, and Southeast Asia
• Caused by
– International wood sales
– Cattle grazing (demand for beef)
– Settlement purposes
Desertification in the Grasslands
• A spread of desert-like conditions in Africa,
Australia, and South Asia
• Caused by
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Poor cropping practices
Overgrazing
The buildup of salt in soils from irrigation
Climatic fluctuations
Water Resources
Water stress
• Calculated from the amount of fresh water
available per person
• describes and predicts where water resource
problems will be the greatest
• Africa stands out as a region of high water
stress
Water stress in Africa and SW Asia
Flooding
• Cause the most deaths of all natural
disasters (accounts for 50% of natural
disaster-related deaths)
• Caused by
– Population growth (forced people to settle in
low-laying delta lands subject to flooding)
– Deforestation
Food Resources
Industrial agriculture and
traditional agriculture
• Industrial agriculture: practiced on about 25%
of the world’s croplands
– High use of fossil fuels for mechanization,
fertilizer, and pesticide
• Traditional agriculture: practiced by about
50% of the Earth’s population
– Labor intensive; requires less mechanization, less
fertilizer, fewer pesticides; generates lower yields
The Green Revolution
• The increases in global food production since
1950
• resulted from
– Change from traditional mixed crops to monocrops of
genetically altered, high-yield rice, wheat, and corn
seeds
– Intensive applications of water, fertilizers, and
pesticides
– Intensification via the reduction in fallow periods
The Green Revolution
• Associated problems are
– Heavy use of fossil fuels makes Green
Revolution agriculture more vulnerable to oil
price fluctuations
– Environmental damage
– Social costs
Food resources - problem
• Local and regional problems are usually
responsible for food unavailability
• Political problems are usually more responsible
for food shortages as compared to natural events
• Globalization is causing a worldwide change in
food preferences
• Africa and South Asia are regions of greatest
concern
Web resources
• To download the demographic data for each country
http://esa.un.org/unpp/
• To create population pyramids for each county
http://www.census.gov/ipc/www/idbpyr.html
• To know more about plate tectonics theory
http://pubs.usgs.gov/publications/text/understanding.html
• To know more about world climates
http://www.uwsp.edu/geo/faculty/ritter/geog101/lectures/climates_toc.
html
• To know more about global warming
http://yosemite.epa.gov/oar/globalwarming.nsf/content/index.html
• To know more about world biome
http://www.blueplanetbiomes.org