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