34 patterns & processes of environmental change

34 patterns & processes of environmental change -...

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ENVIRONMENTAL CHANGE CHAPTER OUTLINE I. The human impact A. Humankind's impact on the environment 1. May be 25 million types of organisms on Earth 2. Humans are not unique in possessing a culture: chimpanzees, gorillas, orangutans, and dolphins have cultures too. 3. Some biogeographers suggest the next great extinction may be caused by humans B. Alteration of ecosystems 1. Environmental destruction began early a) Fires set to kill entire herds of reindeer and bison b) Maori people arrived in New Zealand about 1,000 years ago and have inflicted c) Polynesians (1) Reduced forest cover to brush (2) Exterminated more than 80 percent of bird species for their feathers d) European fashion had a disastrous impact on African species 2. Traditional as well as modern societies have had devastating impacts on their ecosystems 3. Over the last 500 years both the rate and scale of human modification of the physical environment has increased dramatically C. Environmental stress 1. Obvious actions causing environmental stress a) Cutting of trees b) Emission of pollutants into the atmosphere, and spilling oil into the oceans 2. Less obvious actions a) Burying of toxic wastes that foul groundwater b) Dumping vast amounts of garbage into the oceans and use of pesticides in farming II. Water A. A renewable resource 1. Not distributed evenly across the globe (Figure 1-5) 2. Distribution is sustained through the hydrologic cycle (Figure 34-1) 3. Where precipitation goes a) Much is lost through runoff and evaporation b) Some seeps downward into porous water-holding rocks called aquifers c) Aquifers hold about 50 times as much water as falls on the United States each year 4. Chronic water shortages a) Figure 34-2 shows variations in the moisture index in the United States b) Affects tens of millions of farmers in Africa c) Affects Southern California, causing water rationing during drought periods d) The Biscayne Florida Aquifer is overused and saltwater invasion threatens it 5. Nearly three-quarters of all freshwater used annually by all humanity is used in farming a) California uses about 80 percent of available water for irrigation b) Debate: should cities be provided with water at the expense of California’s
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34 patterns & processes of environmental change -...

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