Ice-Albedo Feedbacks (p. 281)
- How does ice-albedo feedback work?
- What is one problem with ice-albedo feedback as an explanation for amplification of the 100,000 year cycle?
Evidence from the Vostok (and Dome C) Ice Cores (p. 282)
- How long does atmospheric CO2 take
to switch between its typical glacial and interglacial concentrations?
Feedbacks Affecting Atmospheric CO2 on Glacial Time Scales (pp. 282-286)
Role of the Biological Pump
- Atmospheric CO2 dissolves in surface ocean waters. Photosynthetic microorganisms in near-surface ocean waters convert some of that CO2 into organic carbon compounds (consuming other nutrients dissolved in the water, such as iron, nitrogen, and phosphorous, too). When these organisms die, some settle to the ocean floor, depositing their carbon as sediment and effectively removing it from the atmosphere for a very long time. This process is referred to as the "biological pump" of CO2. What would the atmospheric CO2 concentration
be if the biological pump were 100% efficient? What if it shut down
- If the biological pump played a role in glacial-interglacial changes in atmospheric CO2, what about nutrient availability must have differed during glacial times?
Shelf Nutrient Hypothesis
- What is one idea for how the the biological pump might have been more effective during a glacial period than it is today? How would this mechanism of enhancing the biological pump during glacial times (the "shelf nutrient hypothesis") constitute a positive feedback in the climate system? Is this hypothesis supported by data on cadmium concentrations in some of the photosynthetic organisms?
The Iron Fertilization Hypothesis
- How does the "iron fertilization hypothesis" work to explain the amplification of cooling during glacial periods? (That is, how does it constitute a positive feedback in the climate system?)
The Coral Reef Hypothesis
- Without worrying about the details of the chemistry, how are (a) the formation/dissolution of calcium carbonate (CaCO3)
skeletons of corals, (b) sea level, and (c) atmospheric CO2 concentrations
related? How do these relations produce a positive feedback in the climate system? Would the destruction of coral reefs due to ocean acidification (a byproduct of the increase in CO2 dissolving in the ocean as atmospheric CO2 levels rise) and other stresses, strengthen or weaken the feedback?
Changes in Terrestrial Biomass: A Negative Feedback (pp.
- Was there more or less terrestrial biomass during the last glacial maximum? Does this
change help explain the observed changes in atmospheric CO2?
Cloud-Albedo Feedbacks (pp. 287-289)
- What is MSA? What produces it? What are the affects on cloud formation?
- How has MSA varied through glacial-interglacial cycles?
The Younger Dryas (pp. 288-290)
- Broadly speaking, when did the last glacial period begin to transition to the current interglacial period? What was the Younger Dryas event, when did it occur, and how long did it last? Was it primarily a regional phenomenon or worldwide?
North Atlantic Deep-Weater Formation
- What is a leading candidate to explain the strong regional focus of the Younger Dryas climate change?
An On-Off Switch in the North Atlantic
- What evidence suggests that the Younger Dryas climate change occurred rather abruptly (in less than a decade)?