Answer 10 of 11 questions
Due Tuesday, Feb. 13
1) Describe briefly (i.e., in 2-3 sentences) the distinction between
the 'wind
driven ocean circulation' and the 'thermohaline
circulation'.
2) Describe briefly how the biological pump affects the vertical distribution
of
dissolved carbon dioxide, acidity and nutrients
in the oceans. Why do carbonate
sediments form only in shallow seas? What
would happen to atmospheric carbon
dioxide concentrations if the biological pump abruptly
shut down?
3) Describe with a sketch or flow chart and a few sentences of explanation
how
the carbonate - silicate cycle works. For which
of the time intervals considered
in the five group presentations this week is the
carbonate - silicate cycle
important? For each of the intervals that you mention,
briefly describe how this
cycle is believed to have influenced the temperature
of the earth.
4) Explain what is meant by 'photosynthesis'. Where does the word
'photosynthesis' come from? Write the chemical formulas
for the photosynthesis
reaction and the respiration and decay reactions.
Other than being in opposing
directions, what else about these two reactions
is different?
5) How can information about the size of the reservoir of organic carbon
buried
in sedimentary rocks in the earth's crust in be
used to estimate the amount of
oxygen produced by photosynthesis over the lifetime
of the earth?
6) If all living biomass burned or decayed and all the carbon dioxide
that was
released remained in the atmosphere, by what fraction
would the carbon dioxide
concentration of the atmosphere rise relative to
its present value? Explain your answer.
7) If evaporation were instantly turned off but precipitation continued
at its
present rate, all the water vapor presently in the
atmosphere would rain (or
snow) out in about a week. On the basis of this
information, estimate the
'residence time' of water vapor in the atmosphere.
8) In what way might the evolution of the earth system have been different
if
hydrogen had not been escaping to space?
9) How does the amount of O2 in today's atmosphere compare
with the amount that
has been produced by photosynthesis over the lifetime
of the earth? Where did
the O2 produced by photosynthesis that
is not still in the atmosphere end up?
10) What orbital conditions (tilt of the earth's axis, time of the calendar
year
when the earth's orbit passes closest
to the sun, and the ellipticity of the
orbit) are most favorable for ice ages,
given the current configuration of
continents and why? Are the current
conditions of the earth's orbit relatively
favorable or unfavorable for an ice
age? Will they be more or less favorable,
say 5000 years from now than they are
now?
11) Name and briefly describe two positive feedbacks that may have rendered
the
earth system more sensitive to orbital
variations than it would be if it simply
responded to the radiation changes.