GEOL 5430

Paleoceanography and Paleoclimatology

Fall 2009

Meets: Tuesdays and Thursdays 9:30-10:45 am, Benson Earth Sciences 355
Professor: Tom Marchitto, tom.marchitto@colorado.edu
Office Hours: Tuesdays 11:00-12:00, Benson 435, or by appointment

3 Credits
Counts toward the Graduate Certificate in Oceanography

Introduction: An understanding of the modes and mechanisms of past climate variability is a vital prerequisite for understanding our current and future climate. Past changes in oceanic and atmospheric circulation are known to have far exceeded the range of variability observed during the instrumental period. Such past changes offer important insights into the basic workings of the Earth’s climate, including its carbon cycle. In addition, dramatic paleoclimate shifts have occurred over periods as short as a decade, a time scale of obvious societal interest. Could similar shifts recur in a future “Greenhouse” world?

Course description: Examines scientific tools, data, and theories related to the dramatically varied past climate of the Earth. Focus will be on marine records of climate change and ocean circulation, but ice core and continental archives will also be discussed. Course will cover the Cretaceous Period to the present, with particular emphasis on the past 150,000 years (the last ice age cycle). Prereq., intro geology or equivalent. Recommended prereq., intro oceanography or atmospheric science.

Grading: 55% homework, 10% draft research proposal, 25% final research proposal, 10% class participation (includes attendance).

Homework: Six homework assignments will allow students to apply what they have learned in class to practical problems. Math will generally be limited to algebra, plus a little calculus. Homework assignments are to be handed in during class, and late assignments will lose 10% credit per day (not per class meeting).

Research proposal: Students will write an NSF-style research proposal exploring some original topic in paleoceanography or paleoclimatology. Proposals should include background information, a testable hypothesis, and a feasible research plan. The assignment will be split into two parts, with a mid-term draft that the instructor will provide comments on, followed by a final version due near the end of the semester. The last homework assignment will require each student to anonymously review two of their classmates' proposals. Proposal topics should be fundamentally different from students' thesis topics.

Reading: Weekly readings will be taken from the research literature and from select textbooks. These will be periodically supplied as pdfs, and students are encouraged to build a binder packet for the course. Bill Ruddiman's textbook Earth's Climate: Past and Future (1st Ed., 2001) will also be on reserve in the Earth Science library for those in need of supplemental reading. Many useful readings will be found in the Encyclopedia of Quaternary Science (EQS), which is available electronically through your university account.

Class Schedule, Reading, and Useful Links
click on lecture title for PowerPoint file (password-protected)

T 8/25: Intro to paleoceanography and paleoclimatology
motivation, approaches, ocean vs. land, dating, timescales of change

Th 8/27: Overview of radiative balance and atmospheric circulation
Stefan-Boltzmann law, greenhouse effect, radiative forcings, atmospheric cells and prevailing winds
Reading: see Chapter 2 of Ruddiman, Earth's Climate: Past and Future (1st Ed., 2001) if you need a very basic review

T 9/1: Overview of ocean circulation
temperature and salinity, wind-driven circulation, deep ocean circulation
Reading: see Chapter 2 of Ruddiman, Earth's Climate: Past and Future (1st Ed., 2001) if you need a very basic review

Th 9/3: Milankovitch orbital theory
ice ages, insolation, eccentricity, precession, obliquity
Reading: Berger and Loutre, Milankovitch theory and paleoclimate, from EQS, 2007.
Link: Berger and Loutre database of orbital parameters and insolation

T 9/8: Oxygen isotopes: Paleotemperature and global ice volume
stable isotope fractionation (inorganic), mass spectrometry, Emiliani curve, hydrologic Rayleigh fractionation
Reading: Dansgaard and Tauber, Glacier oxygen-18 content and Pleistocene ocean temperatures, Science, 166: 499-502, 1969.
Reading: Rohling, Oxygen isotopic composition of seawater, from EQS, 2007.

Th 9/10: Milankovitch confirmed: Spectral analysis and SPECMAP
Fourier theorem, orbital tuning, SPECMAP stack
Reading: Hays et al., Variations in the Earth's orbit: Pacemeaker of the Ice Ages, Science, 194: 1121-1132, 1976.
Reading: Bassinot, Oxygen isotope stratigraphy of the oceans, from EQS, 2007.
Homework 1 due

T 9/15: Marine microfossils and paleoecological factor analysis
foraminifera, Imbrie-Kipp factor analysis, CLIMAP, MARGO
Reading: CLIMAP Project Members, The surface of the ice-age Earth, Science, 191: 1131-1137, 1976.
Reading: MARGO Project Members, Constraints on the magnitude and patterns of ocean cooling at the Last Glacial Maximum, Nature Geoscience, 2: 127-132, 2009.
Link: CLIMAP LGM interactive map

Th 9/17: Ocean temperatures from alkenones and foraminiferal Mg/Ca
salinity and d18O, Uk37 saturation index, Gibbs-Helmhotz thermodynamics, dissolution and calcite saturation effects
Reading: Sachs et al., Biomarkers, from EQS, 2007.
Reading: Rosenthal and Linsley, Mg/Ca and Sr/Ca Paleothermometry, from EQS, 2007.

T 9/22: Climate information from terrigenous marine sediments
Stokes Law, clays, IRD, Heinrich events
Reading: Bond et al., Correlation between climate records from North Atlantic sediments and Greenland ice, Nature, 365: 143-147, 1993.
Reading: Hemming, Terrigenous Sediments, from EQS, 2007.

Th 9/24: Ice cores: Glaciology and water isotopes I
deuterium, plastic deformation, dating, Greenland records
Reading: Brook, Stable isotopes, from EQS, 2007.
Reading: NGRIP Project Members, High-resolution record of Northern Hemisphere climate extending into the last interglacial period, Nature, 431: 147-151, 2004.
Link: Ice core data
Homework 2 due

T 9/29: Ice cores: Water isotopes II
borehole temperatures, thermal fractionation, Antarctic records, deuterium excess, tropical ice cores
Reading: EPICA community members, Eight glacial cycles from an Antarctic ice core, Nature, 429: 623-628, 2004.
Reading: EPICA community members, One-to-one coupling of glacial climate variability in Greenland and Antarctica, Nature, 444: 195-198, 2006.

Th 10/1: Ice cores: Ancient atmospheres
bubble formation, CO2, CH4, d18O2
Reading: Luthi et al., High-resolution carbon dioxide concentration record 650,000-800,000 years before present, Nature, 453: 379-382, 2008.
Reading: Ahn and Brook, Atmospheric CO2 and climate on millennial time scales during the last glacial period, Science, 322: 83-85, 2008.

T 10/6: Terrestrial paleoclimate: Surficial geology
ELAs, periglacial features, loess, lake levels
Reading: Porter, Loess Records: China, from EQS, 2007.
Homework 3 due

Th 10/8: Pollen and tree rings
pollen diagrams, isopolls, isochrones, crossdating, detrending
Reading: Cook et al., North American Drought: Reconstructions, causes, and consequences, Earth-Science Reviews, 81: 93-134, 2007.
Link: Arizona tree ring lab
Link: LDEO tree ring lab

T 10/13: Climate models
components, energy balance models, EMICs, GCMs
Reading: Harrison, Paleoclimate modeling: Data-model comparisons, from EQS, 2007.
Link: PMIP2
Link: EdGCM

Th 10/15: Millennial-scale climate change and North Atlantic Deep Water
NADW formation, GNAIW, Younger Dryas, hysteresis
Reading: Stocker, Past and future reorganizations in the climate system, Quaternary Science Reviews, 19: 301-319, 2000.
Draft Proposal due

T 10/20: GSA - No class

Th 10/22: Paleonutrients and deep ocean circulation
non-conservative passive tracers, d13C, Cd/Ca, d13Cas, Ba/Ca, Zn/Ca
Reading: Marchitto, Nutrient proxies, from EQS, 2007.
Reading: Marchitto and Broecker, Deep water mass geometry in the glacial Atlantic Ocean: A review of constraints from the paleonutrient proxy Cd/Ca, Geochemistry, Geophysics, Geosystems, 7(12), Q12003, doi:10.1029/2006GC001323, 2006.

T 10/27: Kinematic proxies of deep ocean circulation
epsilon Nd, Pa/Th, paleogeostrophy, deep sea T & S
Reading: McManus et al., Collapse and rapid resumption of Atlantic meridional circulation linked to deglacial climate changes, Nature, 428: 834-837, 2004.
Reading: Adkins et al., The Salinity, Temperature, and 18O of the Glacial Deep Ocean, Science, 298: 1769-1773, 2002.

Th 10/29: Radiocarbon: Dating tool and marine tracer
production and decay, complications, calibration, ocean circulation, solar variability, anthropogenic impacts
Reading: Burr, Radiocarbon dating: Causes of temporal variations, from EQS, 2007.
Reading: Marchitto et al., Marine radiocarbon evidence for the mechanism of deglacial atmospheric CO2 rise, Science, 316, 1456-1459, 2007.
Link: CALIB radiocarbon calibration
Link: Fairbanks radiocarbon calibration

T 11/3: U/Th dating and sea level history
tectonics, viscoelastics, U-Th systematics, LGM, MIS 5e
Reading: Fairbanks, A 17,000-year glacio-eustatic sea level record: influence of glacial melting rates on the Younger Dryas event and deep ocean circulation, Nature, 342: 637-642, 1989.
Additional (long) reading if interested: Edwards et al., Uranium-series dating of marine and lacustrine carbonates, Reviews in Mineralogy and Geochemistry, 52(1): 363-405, 2003.
Homework 4 due

Th 11/5: Paleo-monsoon and ITCZ movement
Guest lecture by Sean Bryan

T 11/10: Cenozoic atmospheric CO2 and tectonics
d13Corg, d11B, stomata, caliche, BLAG, Tibet
Reading: Pagani et al., The role of terrestrial plants in limiting atmospheric CO2 decline over the past 24 million years, Nature, 460: 85-88, 2009.
Homework 5 due

Th 11/12: Glacial-interglacial atmospheric CO2 and ocean chemistry
solubility pump, biological pump, carbonate compensation
Reading: Sigman and Boyle, Glacial/interglacial variations in atmospheric carbon dioxide, Nature, 407: 859-869, 2000.

T 11/17: Late Cretaceous to Eocene (99-34 Ma): Greenhouse world
K-T impact, Strangelove ocean, PETM, cool tropics paradox
Reading: Zachos et al., Trends, rhythms, and aberrations in global climate 65 Ma to present, Science, 292: 686-693, 2001.

Th 11/19: Oligocene to Miocene (34-5 Ma): Descent into the Icehouse
Antarctic glaciation, Monterey Hypothesis, grasslands, Messinian Salinity Crisis
Reading: Pearson et al., Atmospheric carbon dioxide through the Eocene Oligocene climate transition, Nature, 461: 1110-1113, 2009.
Reading: Cerling, et al., Global vegetation change through the Miocene/Pliocene boundary, Nature, 389: 153-158, 1997.
Final Proposal due

T 11/24: Fall Break- No class

Th 11/26: Fall Break- No class

T 12/1: Plio-Pleistocene (past 5 Ma): Northern Hemisphere glaciation and appearance of humans
Panama, NADW, 20-40-100 k worlds, hominids
Reading: Raymo et al., Plio-Pleistocene Ice Volume, Antarctic Climate, and the Global d18O Record, Science, 313: 492-495, 2006.
Reading: Huybers and Wunsch, Obliquity pacing of the late Pleistocene glacial terminations, Nature, 434: 491-494, 2005.

Th 12/3: Holocene (past 10 ka): Relative stability and dawn of agriculture
deglaciation, hypsithermal, neoglaciation
Reading: Kaufman et al., Holocene thermal maximum in the western Arctic (0–180°W), Quaternary Science Reviews, 23: 529-560, 2004.
Reading: Mayewski et al., Holocene climate variability, Quaternary Research, 62: 243-255, 2004.

T 12/8: Past 1000 yrs: Medieval Warm Period and Little Ice Age
glaciers, Vikings, forcings, NAO, ENSO, hemispheric reconstruction
Reading: Mann and Jones, Global surface temperatures over the past two millennia, Geophysical Research Letters, 30(15): 1820, 2003.
Reading: Mann et al., Global Signatures and Dynamical Origins of the Little Ice Age and Medieval Climate Anomaly, Science, 326: 1256-1260, 2009.

Th 12/10: Anthropocene and future climate: 'Inevitable surprises?'
global temperatures, greenhouse gases, climate sensitivity, sea level, NADW
GISS temperature analysis
CDIAC greenhouse gas trends
Intergovernmental Panel on Climate Change (IPCC4)
Arctic Climate Impact Assessment
US Global Change Research Program
Homework 6 due