Geoscience Reference
In-Depth Information
last glacial maximum. The consequences of increasing
temperatures over the next 100 years are expected to
be a rise in sea level, shifts in agriculture, damage to
ecosystems, more extreme weather, heat-related health
problems, enhanced malaria and influenza, and air pol-
lution mortality. Efforts to date to control emissions
of greenhouse gases have been weak internationally,
although such emissions continue to grow worldwide.
Some recent efforts on both national and international
scales, though, provide hope for a breakthrough in emis-
sion controls in the near future. Another method of
addressing the problem is through expansion of exist-
ing clean energy technologies. This method is discussed
in Chapter 13.
12.11. Explain the fundamental reason for the four gla-
cial periods that have occurred during the past 450,000
years. Did carbon dioxide cause these events, or did its
mixing ratio change in response to them? Why?
12.12. What is unusual about the rate of change in the
Earth's near-surface temperature since the late 1950s
compared with historic rates of temperature change?
12.13. How would a change in the Earth's obliquity to
zero (no tilt) affect seasons? How would it affect the
relative amount of sunlight over the South Pole during
the Southern Hemisphere winter in comparison with
today?
12.14. If the Earth's temperature initially decreases and
only the snow-albedo feedback is considered, what will
happen to the temperature subsequently?
12.15. If the Earth's temperature initially increases and
only the plant-carbon dioxide feedback is considered,
what will happen to the temperature subsequently?
12.8. Problems
12.1. Calculate the effective temperature of the Earth's
surface in the absence of a greenhouse effect assuming
A e =
1.0. By what factor does the result
change if the Earth-sun distance is doubled?
0.4 and
ε e =
12.16. How will absorbing aerosol particles in the
boundary layer affect air pollution buildup and cloud
formation if only the effects of the aerosol particles on
atmospheric stability are considered?
12.2. What is the relative ratio of energy received at the
top of Mars's and Venus's atmosphere compared with
that at the top of the Earth's atmosphere?
12.3. Explain, in terms of atmospheric components and
distance from the sun, why Mars's actual temperatures
are colder and Venus's actual temperatures are much
warmer than are those of the Earth.
12.17. Explain in your own words why absorbing
aerosol particles might increase cloudiness when they
are in low concentration but decrease cloudiness when
they are in high concentration, as observed in data. Iden-
tify specific feedback effects in your explanation.
12.18. Identify three benefits of controlling black car-
bon emissions and discuss whether each benefit is
greater than, the same as, or less than controlling carbon
dioxide emissions.
12.19. Using STREs from Table 12.6, compare the 20-
and 100-year CO 2 (g)-eq emissions of a diesel vehicle
that emits 112 g-CO 2 (g)/km and 8 mg-FS-C/km (in
which FS is fossil-fuel soot) and a gasoline vehicle that
emits 10 percent more CO 2 (g)/km, but one-sixteenth
the FS-C/km. Calculate low and high estimates for
each case. Which vehicle emits more CO 2 (g)-eq over
20 years? Which emits more over 100 years? Try
to interpret the result. Which vehicle produces more
health-affecting particulate matter?
12.4. What would the equilibrium temperature of the
Earth be if it were in Mars's orbit? What about if it were
in Venus's orbit? Assume no other characteristics of the
Earth changed.
12.5. Discuss at least two ways that deforestation can
affect global warming.
12.6. Explain how CFCs, HCFCs, and HFCs might
contribute to global warming.
12.7. Explain why greenhouse gases may cause an
increase in near-surface temperatures but a decrease
in stratospheric temperatures.
12.8. Explain why the Earth's temperature during the
Archean eon might have been much warmer than
today's temperature, although that period's solar out-
put was lower than today's solar output.
12.9. Essay Questions
12.20. Identify at least six activities that you do or prod-
ucts that you consume that result in the release of one
or more greenhouse gases, and identify ways that you
can reduce your emissions.
12.9. Why are scientists more concerned about the col-
lapse of the West than the East Antarctic ice sheet?
12.10. Explain the common theory as to how the
dinosaurs became extinct.
 
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