THE LIVING WORLD
Unit Eight. The Living Environment
38. Human Influences on the Living World
The development of appropriate solutions to the world’s environmental problems must rest partly on the shoulders of politicians, economists, bankers, engineers—many kinds of public and commercial activity will be required. However, it is important not to lose sight of the key role often played by informed individuals in solving environmental problems. Often one person has made the difference; two examples serve to illustrate the point.
The Nashua River
Running through the heart of New England, the Nashua River was severely polluted by mills established in Massachusetts in the early 1900s. By the 1960s, the river was clogged with pollution and declared ecologically dead. When Marion Stoddart moved to a town along the river in 1962, she was appalled. She approached the state about setting aside a “greenway” (trees running the length of the river on both sides), but the state wasn’t interested in buying land along a filthy river. So Stoddart organized the Nashua River Cleanup Committee and began a campaign to ban the dumping of chemicals and wastes into the river. The committee presented bottles of dirty river water to politicians, spoke at town meetings, recruited businesspeople to help finance a waste treatment plant, and began to clean garbage from the Nashua’s banks. This citizen’s campaign, coordinated by Stod- dart, greatly aided passage of the Massachusetts Clean Water Act of 1966. Industrial dumping into the river is now banned, and the river has largely recovered (figure 38.21).
Figure 38.21. Cleaning up the Nashua River.
The Nashua River, seen on the left in the 1960s, was severely polluted by factories along its banks dumping their wastes directly into the river. Seen on the right today, the river is mostly clean.
A large, 86-square-kilometer freshwater lake east of Seattle, Lake Washington became surrounded by Seattle suburbs in the building boom following the Second World War. Between 1940 and 1953, a ring of 10 municipal sewage plants discharged their treated effluent into the lake. Safe enough to drink, the effluent was believed “harmless.” By the mid-1950s a great deal of effluent had been dumped into the lake (try multiplying 80 million liters/day x 365 days/year x 10 years). In 1954, an ecology professor at the University of Washington in Seattle, W. T. Edmondson, noted that his research students were reporting filamentous blue-green algae growing in the lake. Such algae require plentiful nutrients, which deep freshwater lakes usually lack—the sewage had been fertilizing the lake! Edmondson, alarmed, began a campaign in 1956 to educate public officials to the danger: Bacteria decomposing dead algae would soon so deplete the lake’s oxygen that the lake would die. After five years, joint municipal taxes financed the building of a sewer to carry the effluent out to sea. The lake is now clean (figure 38.22).
Figure 38.22. Lake Washington, Seattle.
Lake Washington in Seattle is surrounded by residences, businesses, and industries. By the 1950s, the dumping of sewage and the runoff of fertilizers had caused an algal bloom in the lake, which would eventually deplete the lake's oxygen. Efforts to clean up the lake began in 1956. The lake is now clean.
Solving Environmental Problems
It is easy to become discouraged when considering the world’s many environmental problems, but do not lose track of the single most important conclusion that emerges from our examination of these problems—the fact that each is solvable. A polluted lake can be cleaned; a dirty smokestack can be altered to remove noxious gas; waste of key resources can be stopped. What is required is a clear understanding of the problem and a commitment to doing something about it. The extent to which U.S. families recycle aluminum cans and newspapers is evidence of the degree to which people want to become part of the solution, rather than part of the problem.
Key Learning Outcome 38.11. In solving environmental problems, the commitment of one person can make a critical difference.
Inquiry & Analysis
The controversy over global warming has two aspects. The first contentious issue is the claim that global temperatures are rising significantly, a profound change in the earth's atmosphere and oceans referred to as "global warming.” The second contentious issue is the assertion that global warming is the consequence of elevated concentrations of carbon dioxide in the atmosphere as a consequence of the widespread burning of fossil fuels.
Resolution of the second issue requires detailed science and is only now reaching consensus acceptance. Resolution of the first issue is a simpler proposition, because it is, in essence, a data statement. The graph to the right displays the data in question—global air temperatures for the last century and a half. Temperature data is collected from measuring stations across the globe, as shown in the image below, and averaged. The bars of the histogram represent mean yearly global air temperatures for each year since 1850. In order to dampen the effects of random year-to-year variations and so better reveal accumulating influences, the data are presented as an anomaly histogram (in an anomaly histogram, each bar presents the deviation of the value during that period from the average value determined for some standard period). In this instance, the anomaly histogram shows the deviation of each year's global mean air temperature from the mean of these values observed over a standard 30-year period between 1961 and 1990.
1. Applying Concepts
a. Variable. In the plot, is there a dependent variable? If so, what is it?
b. Anomaly Histograms. What fraction of the 155 years do not deviate from the 1961-1990 mean value? What fraction deviates more than +0.2°C? more than -0.2°C? more than +0.4°C? more than -0.4°C?
2. Interpreting Data
a. Of the years that deviate more than +0.2°C, how many are before 1940? between 1940 and 1980? after 1980? What fraction occurs after 1980?
b. Of the years that deviate more than +0.4°C, how many are before 1980? after 2000? What fraction occurs after 2000?
c. Of the years that deviate more than -0.2 °C, how many are before 1940? between 1940 and 1980? after 1980? What fraction occurs before 1940?
d. Of the years that deviate more than -0.4°C, how many are before 1940? 1900? What fraction occurs before 1900?
3. Making Inferences If you were to pick a year at random between 1850 and 1900, would it be most likely to deviate +0.2, +0.4, 0, -0.2, or -0.4? a year between 1900 and 1940? a year between 1940 and 1980? a year after 1980? a year after 2000?
4. Drawing Conclusions Has the global air temperature been warming progressively over the last century and a half?
1. “Gray-air cities” are the result of
a. biological magnification of air pollutants.
b. chlorinated hydrocarbons as a major air pollutant.
c. pesticides as a major air pollutant.
d. sulfur oxides as a major air pollutant.
2. The main cause of acid rain is
a. car and truck exhaust.
b. coal-powered industry.
d. chlorinated hydrocarbons.
3. Global warming affects all of the following except
a. rain patterns.
b. rising sea levels.
c. ozone levels.
4. Destruction of the ozone layer is due to
a. car and truck exhaust.
b. coal-powered industry.
d. chlorinated hydrocarbons.
5. The factor most responsible for present-day extinctions is
a. habitat loss.
b. overexploitation of species.
c. introduction of new species.
d. All of these are equally responsible.
6. Free market economies often promote pollution. This is because
a. environmental costs are hardly ever recognized as part of the economy.
b. supply never keeps up with demand, so industry must increase output to address the demand.
c. the costs of energy and raw materials are so variable.
d. laws about pollution are unenforceable.
7. Preserving biodiversity is
a. needed to preserve possible direct value from species, such as new medicines.
b. not needed as extinction is a “natural” cycle and should not be disturbed.
c. needed to make sure all niches are filled.
d. not needed as it interferes with industrial development.
8. Which factor is not responsible for the large increase in the human population over the last 300 or so years?
a. larger and more reliable food reserves from the modernization of farming techniques
b. decreasing mortality rate due to improvements in medicine
c. increasing amounts of open space as countries develop
d. increased sanitation practices
9. Removal of the endangered black-footed ferret and California condor populations from the wild for breeding programs in zoos and field laboratories are examples of preservation through
a. pristine restoration.
b. habitat restoration.
c. habitat rehabilitation.
d. captive propagation.
10. If the removal of a species causes an ecosystem to collapse, that species is known as a(n)
a. keystone species.
b. endangered species.
c. threatened species.
d. None of the above.