ATMS 211  winter quarter 2001
Assignment #3

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.