1. What are the characteristics of ice ages that the first research study seeks to address, and what approach
was adopted in this study to achieve its goals? (5 points; a strong answer will quantify atmospheric levels
of CO2 and global temperatures during glacial episodes and explain the focus of the study.)
2. Why is the ocean the greatest regulator of CO2 in Earth’s atmosphere and how does the concept of a
“biological pump” help explain the role of the ocean in sequestering CO2? (5 points; a strong answer
will describe the significance of the ocean carbon reservoir, explain the nature of the “biological pump”
and its influence on atmospheric CO2.)
3. Why is the incorporation of studies of deep-sea corals from the Southern Ocean of critical importance
to the study? (5 points; a strong answer will explain the specific characteristics of the Southern Ocean
in terms of modern phytoplankton productivity and the “biological pump.”)
4. How does measurement of nitrogen isotopes (
14N to 15N ratios) in deep-sea corals provide a measure of
the efficiency of the “biological pump”, and how do the nitrogen isotope data from the last ice age help
understand influences on atmospheric levels of CO2 during glaciations? (5 points; a strong answer will
explain the controls on the nitrogen isotopic composition of deep-sea corals and how their variations
reflect the efficiency of the “biological pump” and atmospheric levels of CO2.)
5. What two biological processes in coccolithophores are reflected in their carbon isotopic compositions?
