themes in world regional geography
DESCRIPTION
Themes in World Regional Geography. Geo100 - Fall 2003 Julie Hwang Lecture #3. Outlines. Environmental Geography Landform Climates Vegetation Water resources Food resources. How is Earth’s surface shaped?. Jigsaw puzzle fit of South America to Africa Mid-Atlantic Ridge - PowerPoint PPT PresentationTRANSCRIPT
Themes in World Regional Geography
Geo100 - Fall 2003
Julie Hwang
Lecture #3
Outlines
• Environmental Geography– 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
Pangaea
225 million years ago
Laurasia
Gondwanaland
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
PlatesPlates
(solid)
(molten)
Plates drift upon the asthenosphere
Plate Tectonics
Convection Convection cellcell
Plates move relative to one another driven by convection cell
PlatesPlates
Plate Tectonics
• Convergent plate boundary
VolcanoesSubduction Subduction
zonezone
Plate Tectonics – landforms shaped by convergent plate boundary
Plate Tectonics
• Divergent plate boundary
Mid-Ocean Ridge
Rift ValleyRift Valley
Plate Tectonics – landforms shaped by divergent plate boundary
Olduvai Gorge (Tanzania)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
Equator
20° N
40° N
40° S
20° 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
• 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
– Carbon dioxide (CO2)– Chlorofluorocarbons (CFCs)– Methane (CH4)– Nitrous oxide (N2O)
Effects of Global Warming
• Climate changes– 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 war
ming was formulated
• Kyoto protocol (’97)– 38 industrialized countries agree to reduce the e
missions 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 forest Savannas
Deserts Grasslands: Mediterranean, Temperate
Temperate Forests: Deciduous, Coniferous
Tundra Icecap
Tropical
Dry, Temperate
Temperate
Polar,
Highland
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 polewa
rd of the tropics– Comprise one-third of the Earth’s land surface– Prairie: North American grassland– Steppe: shorter, less dense grassland found in Russia a
nd 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 – 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 g
enetically 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 countryhttp://esa.un.org/unpp/
• To create population pyramids for each countyhttp://www.census.gov/ipc/www/idbpyr.html
• To know more about plate tectonics theoryhttp://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 warminghttp://yosemite.epa.gov/oar/globalwarming.nsf/content/index.html
• To know more about world biomehttp://www.blueplanetbiomes.org