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 day65 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 Plates (solid) (molten) Plates drift upon the asthenosphere

Plate Tectonics Convection cell Plates move relative to one another driven by convection cell Plates

Plate Tectonics Convergent plate boundary Volcanoes Subduction zone

Plate Tectonics – landforms shaped by convergent plate boundary

Plate Tectonics Divergent plate boundary Mid-Ocean Ridge Rift Valley

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 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 (CO 2 ) –Chlorofluorocarbons (CFCs) –Methane (CH 4 ) –Nitrous oxide (N 2 O)

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 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 forest Savannas DesertsGrasslands: 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 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 –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 To create population pyramids for each county To know more about plate tectonics theory To know more about world climates html To know more about global warming To know more about world biome