Course description: A yearly investigation, in seminar format, of major problems in the study and understanding of Quaternary climate variation. Each year one or two major topics will be addressed, which may include: physics and chemistry of the glacial ocean circulation; theory and mechanics of glacial/interglacial atmospheric CO2 change; the origin of the 100 kyr climate cycle; and reconciling snowlines, sea surface temperatures, moist thermodynamics, and winds during the last glacial maximum. In Fall ’08, we will focus on the theory and mechanics of glacial/interglacial atmospheric CO2 change. Expectations and grading: Students will be required to make presentations on assigned readings from both the historic and current research literature. There will be one or two discussion leaders per week, but everyone is responsible for reading the papers and participating in the discussion. Presentations should go beyond the papers at hand by providing relevant background material that helps to place the papers in the context of previous studies. We are not looking for an exhaustive summary of the reading, but rather a framework from which the group can discuss and better understand the papers. Grades will be based on the quality of presentations (60%) and on overall participation, which includes attendance (40%). Readings will be available either as online pdfs or as hardcopies on reserve in the INSTAAR Reading Room and the Geology Library. _________________________________________________________________________________ Meets: Wednesdays 10am-12pm, RL1 room 233 _________________________________________________________________________________
Week 1 (W 8/27, 4 pm): Organizational meeting
Week 2 (W 9/3): Natural carbon cycle and speciation of CO2 in seawater (instructor presentations)
Week 3 (W 9/10): Continental shelf hypothesis
Week 4 (W 9/17): Coral reef hypothesis
Week 5 (W 9/24): Polar dominance (Harvardton Bears)
Week 6 (W 10/1): Nutrient deepening and polar alkalinity
Week 7 (W 10/8): Rain ratio hypothesis
Week 8 (W 10/15): Polar nutrient utilization
Week 9 (W 10/22): Polar stratification and gas exchange
Week 10 (W 10/29): Deep ocean chemical divide
Week 11 (W 11/5): Nitrogen fixation and denitrification
Week 12 (W 11/12): Paleo-atmospheric d13C
Week 13 (W 11/19): Paleo-atmospheric and oceanic D14C
Week 14 (W 12/3): Silicate weathering thermostat
Week 15 (W 12/10): Long-term fate of fossil fuel CO2
Instructors: Scott Lehman, scott.lehman@colorado.edu;
Tom Marchitto, tom.marchitto@colorado.edu
Office Hours: By appointment
Credits: 2Preliminary class schedule (subject to change)
Papers in brackets are placeholders meant to convey the historical progression of the course
Required Reading: Sundquist, The global carbon dioxide budget, Science, 259: 934-941, 1993. (stop when you reach "Historical and Recent CO2 Budget" (p. 937) which is now outdated)
Supplemental Reading: IPCC4, The Physical Science Basis, Chapter 7 provides a good overview of the Earth's current carbon budget
Required Reading: Broecker, Glacial to interglacial changes in ocean chemistry, Progress in Oceanography, 11: 151-197, 1982. (Sean)
Required Reading: Berger, Deglacial CO2 buildup: Constraints on the coral-reef model, Palaeogeography, Palaeoclimatology, Palaeoecology, 40: 235-253, 1982. (Ben)
Required Reading: Opdyke and Walker, Return of the coral reef hypothesis: Basin to shelf partitioning of CaCO3 and its effect on atmospheric CO2, Geology, 20: 733-736, 1992. (Caroline)
Required Reading: Knox and McElroy, Changes in atmospheric CO2: Influence of the marine biota at high latitude, Journal of Geophysical Research, 89: 4629-4637, 1984. (Katie)
Required Reading: Siegenthaler and Wenk, Rapid atmospheric CO2 variations and ocean circulation, Nature, 308: 624-626, 1984. (Sophie)
Required Reading: Sarmiento and Toggweiler, A new model for the role of the oceans in determining atmospheric pCO2, Nature, 308: 621-624, 1984. (Sophie)
Required Reading: Boyle, The role of vertical chemical fractionation in controlling late Quaternary atmospheric carbon dioxide, Journal of Geophysical Research, 93: 15701-15714, 1988. (Whitney)
Required Reading: Broecker and Peng, The Cause of the Glacial to Interglacial Atmospheric CO2 Change: A Polar Alkalinity Hypothesis, Global Biogeochemical Cycles, 3: 215-239, 1989. (Sean)
Required Reading: Archer and Maier-Reimer, Effect of deep-sea sedimentary calcite preservation on atmospheric CO2 concentration, Nature, 367: 260-263, 1994. (Sophie)
Required Reading: Sigman et al., The Calcite Lysocline as a Constraint on Glacial/Interglacial Low-Latitude Production Changes, Global Biogeochemical Cycles, 12: 409-427, 1998. (Katie)
Background Reading: Martin, Glacial-interglacial CO2 change: The iron hypothesis, Paleoceanography, 5: 1-13, 1990. (brief discussion, no presentation)
Required Reading: Sigman and Boyle, Glacial/interglacial variations in atmospheric carbon dioxide, Nature, 407: 859-869, 2000. (Ben)
Required Reading: Keeling and Visbeck, Antarctic stratification and glacial CO2 (comment on Sigman and Boyle, 2000), with reply by Sigman and Boyle, Nature, 412: 605-606, 2001. (Caroline)
Required Reading: Stephens and Keeling, The influence of Antarctic sea ice on glacial–interglacial CO2 variations, Nature, 404: 171-174, 2000. (Caroline)
Required Reading: Morales Maqueda and Rahmstorf, Did Antarctic sea-ice expansion cause glacial CO2 decline?, Geophysical Research Letters, 29(1), 1011, doi:10.1029/2001GL013240, 2002. (Whitney)
Required Reading: Gildor and Tziperman, Physical mechanisms behind biogeochemical glacial-interglacial CO2 variations, Geophysical Research Letters, 28: 2421-2424, 2001. (Whitney)
Required Reading: Toggweiler, Variation of Atmospheric CO2 by Ventilation of the Ocean’s Deepest Water, Paleoceanography, 14: 571-588, 1999. (Sean)
Required Reading: Falkowski, Evolution of the nitrogen cycle and its influence on the biological sequestration of CO2 in the ocean, Nature, 387: 272-275, 1997. (Sophie)
Required Reading: Ganeshram et al., Reduced nitrogen fixation in the glacial ocean inferred from changes in marine nitrogen and phosphorus inventories, Nature, 415: 156-159, 2002. (Sophie)
Required Reading: Leuenberger et al., Carbon isotope composition of atmospheric CO2 during the last ice age from an Antarctic ice core, Nature, 357: 488-490, 1992. (Katie)
Required Reading: Smith et al., Dual modes of the carbon cycle since the Last Glacial Maximum, Nature, 400: 248-250, 1999. (Katie)
Required Reading: Broecker and Barker, A 190 permil drop in atmosphere's D14C during the “Mystery Interval” (17.5 to 14.5 kyr), Earth and Planetery Science Letters, 256: 90-99, 2007. (Whitney)
Required Reading: Marchitto et al., Marine Radiocarbon Evidence for the Mechanism of Deglacial Atmospheric CO2 Rise, Science, 316: 1456-1459, 2007. (Whitney)
Required Reading: Walker et al., A negative feedback mechanism for the long-term stabilization of Earth's surface temperature, Journal of Geophysical Research, 86(C10): 9776-9782, 1981. (Ben)
Required Reading: Zeebe and Caldeira, Close mass balance of long-term carbon fluxes from ice-core CO2 and ocean chemistry records, Nature Geoscience, 1: 312-315, 2008. (Ben)
Required Reading: Falkowski et al., The Global Carbon Cycle: A Test of Our Knowledge of Earth as a System, Science, 290: 291-296, 2000. (Caroline)
Required Reading: Archer, Fate of fossil fuel CO2 in geologic time, Journal of Geophysical Research, 110: C09S05, doi:10.1029/2004JC002625, 2005. (Caroline)