Human+Impact+on+Natural+World+WG

Human Interference with the water cycle (p.499) 1. What are the three ways humans disrupt the natural water cycle? First they withdraw water from aquifers; second, they clear vegetation from land and build roads and building that prevent percolation and increase runoff. 2. What is groundwater mining and what is the danger of this process? Groundwater mining is withdrawals from aquifers exceed any possibility of recharge. The danger is that it is dropping, and residents may run out of groundwater, at least for irrigation purposes, within a few short years. 3. Why is it possible to run out of Freshwater, a renewable resource? Its possible to run out of Freshwater when the available supplies run off instead of entering bodies of Freshwater and aquifers or becomes so polluted that it is not usable.

Human Interference with the carbon cycle (p.501) 1. How are humans increasing the amount of carbon dioxide being deposited in the atmosphere on top of "natural" sources? More carbon dioxide is being deposited in the atmosphere than is being removed. The increase is due to the burning of fossils fuels and the destruction of forests to make way for farmland and pasture. 2. What are the greenhouse gases and what are the human causes of these gases? They are nitrous oxide from fertilizers and animal wastes and methane from bacterial decomposition. 3. Why are these gases called greenhouse gases? They are just like the panes of a greenhouse, they allow solar radiation to pass through but hinder the escape of infrared rays (heat) back into space. 4. What are some possible dangers of global warming? If the temperature rises in the polar region, the glaciers will melt, and sea levels will rise, not only due to this melting but also because water expands as it warms.

Human Interference with the Ozone Shield (p.506) 1. What is the ozone shield and what chemical reaction produces ozone? Thy ozone shield is a layer of ozone that absorbs most of the ultraviolet rays of the sun so that fewer rays strike the earth. The chemical reaction is oxygen molecules, and then the oxygen atoms combine with other oxygen molecules to produce ozone. 2. What are ozone holes? They are severe depletions of the ozone layer. 3. Why are ozone holes dangerous to humans? They are dangerous to humans because 1.75 additional cases of cataracts and 300,000 more skin cancers every year, worldwide. 4. What human pollution destroys ozone molecules? CFCs destroy the ozone molecules. 5. What are commons sources of chlorine pollution? Common sources of chlorine pollution are satellite measurements.

Human Interference and the Arctic (p. 507) 1. What does ANWR stand for and what is it? It stands for Arctic National Wildlife Refuge. It is open to oil exploration to help alleviate our dependence on foreign oil and help lower prices. 2. Why is ANWR the source of political debate? Because ANWR became the focus of much of the debate, in which the value of pristine wilderness was weighed against the value of its energy resourses. 3. What are the benefits of drilling for oil in ANWR? Alaskans would benefit by the creation of new jobs and a boost to the state economy. 4. What are the risks of drilling for oil in ANWR? The risks are oils spills from a pipeline in nearby Prudhoe Bay as evidence that even modern drilling techniques are not immune to pollution events.