GEOL 5700-12

Warm Periods of the Earth's Past

Spring 2007

The Earth has experienced many past intervals of global warmth, in the absence of anthropogenic forcing. Notable examples during the Cenozoic include the Late Paleocene Thermal Maximum, the Early Eocene Climatic Optimum, the Mid-Miocene Climatic Optimum, the last interglacial period (MIS 5e), and the Holocene Hypsithermal. An improved understanding of current global warming may be gained by examining this natural variability.

The course will be conducted in seminar (group discussion) format with interspersed background lectures by the instructor. Students will be required to make presentations on assigned readings from the current research literature. A term project, in the form of an annotated bibliography on a relevant topic of the student’s choosing, will also be required.

Term Project description (pdf) (due May 7)
Example of an annotated bibliography, minus the summary (pdf)
Web of Science database
GeoRef link
Various journal links

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Meets: Tuesdays and Thursdays 9:30-10:45, Benson Earth Sciences 340E
Professor: Tom Marchitto, tom.marchitto@colorado.edu
Office Hours: Tuesdays 10:50-11:30 in Benson 435, or by appointment in RL1 152
Grading: 40% Presentations, 30% Participation, 30% Project

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Pertinent questions to be addressed

What caused past global warmth?

What forcings were important besides CO2?
Did all warm periods have high CO2? (and were all high-CO2 periods warm?)
Are there any good natural analogues for the anthropogenic climate "experiment"?

How did past warm climates differ from today, and why? Some predictions for future climate that may have examples in the past:

Higher sea level?
Less sea ice?
Less permafrost?
Altered hydrologic cycle?
Altered El Nino characteristics?
Increased storminess?
Weaker/different deep ocean circulation?
Decreased marine carbonate saturation?

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Class schedule (subject to change)

T 1/16: Introduction and class overview


Th 1/18: Lecture: Climate primer


Medieval Warm Period

T 1/23: Global temperatures over the past millennium (Ursula)

Osborn and Briffa, The Spatial Extent of 20th-Century Warmth in the Context of the Past 1200 Years, Science, 311: 841-844, 2006.

Hegerl et al., Climate sensitivity constrained by temperature reconstructions over the past seven centuries, Nature, 440: 1029-1032, 2006.


Th 1/25: Atmospheric circulation during the MWP (Laura)

Treydte et al., The twentieth century was the wettest period in northern Pakistan over the past millennium, Nature, 440: 1179-1182, 2006.

Sridhar et al., Large Wind Shift on the Great Plains During the Medieval Warm Period, Science, 313: 345-347, 2006.


Early Holocene Optimum

T 1/30: Arctic temperatures (Corey)

Kaufman et al., Holocene thermal maximum in the western Arctic (0–180°W), Quaternary Science Reviews, 23: 529-560, 2004.


Th 2/1: Indian monsoon (Sarah)

Fleitmann et al., Holocene ITCZ and Indian monsoon dynamics recorded in stalagmites from Oman and Yemen (Socotra), Quaternary Science Reviews, 26: 170-188, 2007.


T 2/6: African Humid Period (Steve)

Kuper and Kropelin, Climate-Controlled Holocene Occupation in the Sahara: Motor of Africa's Evolution, Science, 313: 803-807, 2006.


Th 2/8: Lecture: Quaternary sea levels


Last Interglacial Period (MIS 5e)

T 2/13: Arctic warmth (Benet)

CAPE-Last Interglacial Project Members, Last Interglacial Arctic warmth confirms polar amplification of climate change, Quaternary Science Reviews, 25: 1383-1400, 2006.


Th 2/15: Ice sheets (Jason)

Overpeck et al., Paleoclimatic Evidence for Future Ice-Sheet Instability and Rapid Sea-Level Rise, Science, 311: 1747-1750, 2006.

Otto-Bliesner et al., Simulating Arctic Climate Warmth and Icefield Retreat in the Last Interglaciation, Science, 311: 1751-1753, 2006.


Marine Isotope Stage 11

T 2/20: Analog orbital forcing (Alex)

Loutre, Clues from MIS 11 to predict the future climate – a modelling point of view, Earth and Planetary Science Letters, 212: 213-224, 2003.


Th 2/22: No Class

Pliocene

T 2/27: ENSO (Laura)

Federov et al., The Pliocene Paradox (Mechanisms for a Permanent El Niño), Science 312: 1485-1489, 2006.


Th 3/1: Lecture: Cenozoic Atmospheric CO2


T 3/6: African vegetation (Sarah)

Feakins et al., Biomarker records of late Neogene changes in northeast African vegetation, Geology 33: 977-980, 2005.


Miocene Climatic Optimum

Th 3/8: Southern Ocean temperatures (Corey)

Shevenell et al., Middle Miocene Southern Ocean Cooling and Antarctic Cryosphere Expansion, Science 305: 1766-1770, 2004.


Early Eocene Climatic Optimum

T 3/13: Eocene CO2 and Arctic salinity (Alex)

Lowenstein and Demico, Elevated Eocene Atmospheric CO2 and Its Subsequent Decline, Science 313: 1928, 2006.

Brinkhuis et al., Episodic fresh surface waters in the Eocene Arctic Ocean, Nature 441: 606-609, 2006.


Paleocene-Eocene Thermal Maximum (PETM)

Th 3/15: PETM temperatures (Jason)

Sluijs et al., Subtropical Arctic Ocean temperatures during the Palaeocene/Eocene thermal maximum, Nature 441: 610-613, 2006.

Zachos et al., Extreme warming of mid-latitude coastal ocean during the Paleocene-Eocene Thermal Maximum: Inferences from TEX86 and isotope data, Geology 34: 737-740, 2006.


T 3/20: PETM hydrologic cycle (Ursula)

Schmitz and Pujalte, Abrupt increase in seasonal extreme precipitation at the Paleocene-Eocene boundary, Geology 35: 215-218, 2007.

Pagani et al., Arctic hydrology during global warming at the Palaeocene/Eocene thermal maximum, Nature 442: 671-675, 2006.


Th 3/22: PETM carbon cycle (Alex)

Dickens, Hydrocarbon-driven warming (News and Views), Nature 429: 513-515, 2004.

Zachos et al., Rapid Acidification of the Ocean During the Paleocene-Eocene Thermal Maximum, Science 308: 1611-1615, 2005.


T 3/27, Th 3/29: Spring Break


Paleocene

T 4/3: Vegetation (Benet)

Johnson and Ellis, A Tropical Rainforest in Colorado 1.4 Million Years After the Cretaceous-Tertiary Boundary, Science 296: 2379-2383, 2002.


Th 4/5: Insects and plants (Steve)

Wilf et al., Insect herbivory, plant defense, and early Cenozoic climate change, PNAS 98: 6221-6226, 2001.


T 4/10, Th 4/12, T 4/17: No Class


Cretaceous

Th 4/19: Atmospheric CO2 (Laura)

Nordt et al., Terrestrial Evidence for Two Greenhouse Events in the Latest Cretaceous, GSA Today 13: 4-9, 2003.


T 4/24: Marine temperatures (Sarah)

Huber et al., Deep-sea paleotemperature record of extreme warmth during the Cretaceous, Geology 30: 123-126, 2002.

Wilson et al., Testing the Cretaceous greenhouse hypothesis using glassy foraminiferal calcite from the core of the Turonian tropics on Demerara Rise, Geology 30: 607-610, 2002.


Triassic

Th 4/26: Carbon cycle (Corey)

Payne et al., Large Perturbations of the Carbon Cycle During Recovery from the End-Permian Extinction, Science 305: 506-509, 2004.


Pre-Cambrian

T 5/1: Atmosphere (Benet)

Kasting and Howard, Atmospheric composition and climate on the early Earth, Philosophical Transations of the Royal Society B, 361: 1733-1742, 2006.


Synopsis

Th 5/3: (Tom)

Royer et al., Climate sensitivity constrained by CO2 concentrations over the past 420 million years, Nature 446: 530-532, 2007

IPCC 4th Assessment (see Chapter 6: Paleoclimate)