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Humans in the Biosphere Chapter 6
A Changing Landscape • Growing populations depend on the limited natural resources of earth for survival. • Humans rely on ecological life support systems to provide us with; clean air, water, and fertile soil. • Humans must be aware that our activities on earth have an impact on and can change our environment.
Human Activities • Hunting & Gathering: • Human hunting and gathering causes mass extinction of animals • Agriculture: • Farming destroyed many forests to make farm land. (decrease in oxygen, increase in carbon dioxide). • Fertilizers & pesticides contaminate water supplies • Irrigation strains water supply • Food supply demand puts strain on environment( soil nutrients). • Industrial Growth & Urban Development: • Makes life easier and more productive • Causes pollution (Acid rain).
Renewable & Nonrenewable Resources • Renewable Resource: Resource that can regenerate or be replenished quickly by the earth. • Not unlimited • Example; Water • Nonrenewable Resource: Cannot be replenished by the earth. • Example; Fossil fuels • Sustainable Development: Using natural resources without depleting them and still providing for human need as well as, without causing environmental harm. • Example: Using lady bugs to eat insects that eat crops instead of using insecticides/pesticides.
Human Impact on Renewable Resources • Land Resources: Space for construction, over farming/over grazing. • Soil Erosion- wearing away of surface soil by air & water. • Desertification-turning farmlands into deserts. • Forest Resources: Wood supplies for building and heat, oxygen, habitats, food. • Deforestation-loss of forest that can’t re-grow. • Fishery Resources: Food supply, over fishing. • Aquaculture- Raise aquatic animals for human consumption. • Air Resources: Air quality, pollution, burning of fossil fuels, smog, acid rain. • Freshwater Resources: Only 3 % of water on earth is freshwater, very limited resources.
Charting a Course for the Future • Ozone Depletion: • Ozone Layer: high concentration of ozone gas in the earths atmosphere. • Absorbs UV radiation (sunscreen for the earth). • Ozone Depletion: the breakdown of the ozone layer. • Caused by CFC’s (chloroflurocarbons). • CFC’s mostly banned today. • Scientists predict that damage done to the ozone by CFC’s should be repaired within 50yrs. • Global Warming: Increase in the average temperature of the biosphere. • Caused by humans; Burning of fossil fuels, deforestation, landfills, fertilizers.