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Ch 2
- 1. PHYSICAL PROCESSES AND WORLD REGIONS Chapter 2
- 2. Four Spheres of Earth’s Habitable Environment Lithosphere Earth’s outer “rind” of rock Varies in thickness from about 50 to 125 miles Made up of large sections of rock called plates A work in progress, providing opportunities and threats Hydrosphere Comprised of the Earth’s water features Atmosphere Layer of gases, primarily nitrogen and oxygen Surrounds the earth to roughly 60 miles out Biosphere (Ecosphere) Global ecological system where relationships play out among the lithosphere, hydrosphere, and atmosphere
- 3. 2.1.1 Plate Tectonics Continental Drift Theory by Alfred Wegener, 1912 Continents once joined as supercontinent of “Pangaea” but they “drifted apart” over time Earth’s lithosphere is made up of several plates that move in various directions Seafloor Spreading Process of 2 plates moving away from each other Few impacts on people Converging Plates Trigger some of planet’s greatest natural hazards Subduction (one plate “dives” below another)
- 4. 2.1.1 Plate Tectonics (continued) Seismic Activity Refers to the earth’s vibrations when plates collide Can result in earthquakes, tsunamis, and volcanism Earthquakes Strength Measured on the Richter Scale World’s Largest Recorded Earthquakes Magnitude 9.5 Chile, 1960 Magnitude 9.2 United States, 1964 Magnitude 9.1 Indonesia, 2004 Magnitude 9.0 Japan, 2011 Tsunamis (Tidal Waves) Volcanism Movement of molten earth material Generally occurs along / near subduction zones
- 5. Tectonic Plates & Their Movement Earthquakes, volcanoes, and other geologic events are concentrated where plates separate, collide, or slide past one another. Where they separate, rifting produces very low land elevations or the emergence of new crust on the ocean floor.
- 6. Concentric Layers of the Earth Generalized cross section of the Earth, showing its main concentric layers and the process by which its lithosphere is recycled.
- 7. 2.2 Patterns of Climate and Vegetation Weather Atmospheric conditions occurring at a given time & place Climate Average weather of an area over a long period of time Forces shaping the environment and human interaction with it include: Precipitation Aridity Seasons Climate & Vegetation Types
- 8. 2.2.1 Precipitation Precipitation and Temperature are the key variables in weather and climate Water is essential for life on Earth Precipitation Result of processes that cool the air to release moisture Types of precipitation include: Rain Snow Sleet Hail
- 9. World Precipitation Map Some geographers argue that this is perhaps the most important of all maps in understanding life on earth.
- 10. 2.2.2 Climate and Vegetation Types Climates are a product of precipitation, temperature, latitude, and elevation Biomes Terrestrial ecosystems categorized by dominant types of natural vegetation Major Climate Types Ice Cap, Tundra & Subarctic Desert & Semiarid / Steppe Tropical Rain Forest & Tropical Savanna Marine West Coast Mediterranean Humid Subtropical & Humid Continental Undifferentiated Highland Climate
- 12. World Biomes
- 13. Ice Cap Biome British Columbia, Canada The ice cap biome is devoid of vegetation, except in very few spots where enough ice or snow melts in the summer to allow tundra
- 14. Tundra Northern Norway Tundra vegetation is composed of mosses, lichens, shrubs, dwarfed trees, and some grasses.
- 15. Coniferous Forest British Columbia, Canada Needleleaf evergreen coniferous trees can stand long periods when the ground is frozen, depriving them of moisture. Coniferous forests
- 16. Desert Shrub Sinai Peninsula, Egypt Desert shrub vegetation is often found only in dry riverbeds in arid climates.
- 17. Steppe Eastern Turkey The steppe biome is composed mainly of short grasses and is also referred to as temperate grassland.
- 18. Tropical Rain Forest Dominica, West Indies The tropical rain forest climate is rainy and occurs at low latitudes. Heat and moisture are almost always present in the biome.
- 19. Scrub and Thorn Forest Northern Zimbabwe The tropical deciduous forest thins out to low, sparse scrub and thorn forest in drier areas.
- 20. Savanna Southern Kenya Savanna vegetation, which has taller grasses than the steppe, occurs in areas of greater overall rainfall and more pronounced wet and dry
- 21. Mediterranean Scrub Forest Southern California, USA The Mediterranean climate is characterized by rainless summers contrasted with cyclonic or orographic precipitation in the winter.
- 22. Temperate Mixed Forest Central Missouri, USA The mixed forest is a transitional area where both needleleaf and broadleaf trees are present and compete with each other.
- 23. Undifferentiated Highland Vegetation San Juan Mountains, Colorado, USA Undifferentiated highland climates have a range of conditions based on elevation and exposure to wind and sun. The numerous biomes
- 24. 2.2.3 The Importance of Biodiversity Biological Diversity Number of plant and animal species present and the variety of genetic materials these organisms contain Most diverse biome is the tropical rain forest Struggling to Protect Biodiversity Human removal of rain forests and natural ecosystems depletes biodiversity Controversy of the Green Revolution On one hand, puts more food on the global table But may render crops more vulnerable to pests and diseases Establishment of National Parks and Protected Areas Conservation International’s “Biodiversity Hot Spots”
- 25. World Biodiversity Hot Spots 34 Priority Regions Identified by Conservation International
- 26. 2.4 The World’s Oceans Water comprises about 71% of world’s surface Life on earth would not be possible without the resources of the Hydrosphere: Oceans Freshwater Sources (e.g., lakes, rivers) The World Commission on Water projects that by 2025, half of the world’s population will live under conditions of severe water stress
- 27. 2.4.1 Why Should We Care About Oceans? It’s a watery world 70% of the world’s surface is comprised of water Oceans have the largest role in the hydrologic cycle Seawater is converted into usable freshwater precipitation The oceans feed us 15% of the world’s population relies primarily on fish as their source of protein Global demand for seafood has increased 40% since 1980 They provide energy & raw materials for human use They play important roles in trade and commerce 90% of global trade is seaborne
- 28. Pike Street Market Seattle, Washington
- 29. 2.5 Global Environment Change Although governments have been doing more in recent years to protect the earth’s biodiversity, atmospheric changes have profound impacts on natural systems These atmospheric changes are largely attributable to human activities
- 30. 2.5.1 Climatic Change Human activities are responsible for a documented warming of the earth’s surface Intergovernmental Panel on Climate Change (IPCC) United Nations-sponsored panel Made up of 2,500 atmospheric scientists from 130+ countries 2007 report concluded that global warming is “unequivocal” Global Warming Global mean temperature has increased 1.4 degrees F since late 19th century Result of human production of greenhouse gases, such as Carbon Dioxide
- 31. Carbon Dioxide vs. Mean Global Temperature
- 32. 2.5.2 The Greenhouse Effect Concept established in 1827 by French mathematician Jean-Baptiste Fourier Fourier noted that the earth’s atmosphere acts like the transparent glass cover of a greenhouse, allowing visible sunlight to pass through, and trapping some of the heat In our atmosphere, naturally occurring greenhouse gases make earth habitable by trapping heat from sunlight Concern over global warming focuses on human-derived sources of greenhouse gases, which trap abnormal amounts of heat Particularly problematic are human-produced methane, nitrous-oxide, and chlorofluorocarbons (CFCs)
- 34. 2.5.3 The Effects of Global Warming Effects of Global Warming on the Earth Increase in global temperatures by 3°F to 7°F by 2100 More precipitation overall, but also more pronounced drought Pronounced warming in the polar regions Shifting biomes, with species extinction and agricultural changes Rising sea levels Geopolitical instability
- 36. 2.5.4 Global Climate Change: What Can Be Done? China and the U.S. account for roughly 40% of the entire global emissions output Approaches to confronting climate change Mitigation Switching from coal to cleaner fossil fuels to produce electricity Reducing energy consumption Removing greenhouses from the atmosphere by boosting photosynthesis Adaptation Cope with and reduce the unavoidable impacts of climate change Building sea walls to prevent flooding due to rising sea levels Relocating people from flood-prone areas to higher ground Developing crop varieties that are more suited to expected changes in temperature and precipitation
- 37. 2.5.4 Global Climate Change: What Can Be Done? (continued) Approaches to mitigating climate change Negotiate and implement international treaties to reduce greenhouse gas emissions Montreal Protocol Signed by 37 countries in the late 1980s Production of CFCs worldwide reduced in phases to zero by 2010 Resulted in reduction of stratospheric ozone “holes” Cut emissions through market-based incentives Cap-and-Trade or Emission-Trading Increase carbon sequestration Natural capture and long-term storage of carbon in so-called carbon sinks (forests, farmlands, and oceans), so that the build-up of carbon dioxide in the atmosphere will reduce or slow.