(iii) What is meant by a “sustainable level” of carbon dioxide emissions?
According to these predictions, what needs to happen for this level to be
brought about? (1 point maximum for correctly explaining what is meant
by a “sustainable level” of carbon dioxide emissions and 1 point
maximum for describing what possibly needs to happen for this to occur.)
A “sustainable level” of carbon dioxide emissions is one in which the
amount absorbed by Earth’s natural systems, such as oceans and plants,
equals the amount released into the atmosphere. A combination of both
technological change and slowed population growth is needed to bring
carbon dioxide emissions to sustainable levels. As the graph shows,
neither factor can produce sustainable levels on its own.(b) Maximum 3 points.
Explain the difference between remediation and alleviation of an
environmental problem. Use the example of acid deposition to illustrate the
difference. (1 point maximum for correctly defining remediation. 1 point
maximum for correctly defining alleviation. 1 point maximum for correctly
explaining the difference using acid deposition as an example.) Anything that
reduces the use of fossil fuels or limits the emissions of sulfur and nitrogen
oxides would be an example of alleviation. Anything that neutralizes the
effects of acid in the environment would be an example of remediation. Be
careful in giving just an appropriate level of detail.
Alleviation of an environmental problem means stopping or lessening its
cause. Remediation means cleaning up the effects of the problem.
Acid deposition forms in the atmosphere mainly from sulfur oxides
(SOx) and nitrogen oxides (NOx). Both are present primarily as a
consequence of the combustion of fossil fuels.
Methods of alleviation may concentrate on decreasing the amount of
sulfur and nitrogen oxides released into the atmosphere. Any method of
reducing the rate of consumption of fossil fuels, such as increased use of
nuclear power and alternative energ, !y sources, or laws and education to
help conserve energy, would decrease the amount of sulfur and nitrogen
oxides released. Clean-fuel technologies, such as fluidized-bed combustion
of coal, would result in less of these gases being produced on combustion.
Scrubbers in smokestacks can remove much of what is produced. Perhaps the
most important step in reducing emissions in the United States, however, was
the passing of the Clean Air Act in 1963 and its subsequent amendments.