INSTAAR: Tom Marchitto

Research Scientist of INSTAAR; Assistant Professor of Geological Sciences, Univ. of Colorado at Boulder.

PhD, MIT/WHOI Joint Program, 1999.

Tom.Marchitto@colorado.edu
(303) 492-7739

INSTAAR Directorate Members

Specialty: Quaternary paleoclimate, paleoceanography, and past ocean chemistry.

Research Interests: An understanding of the modes and mechanisms of past climate variability is a vital prerequisite for understanding our current and future climate. I am mainly interested in paleoceanography, specifically large-scale changes in ocean circulation and chemistry that occur over millennial (and shorter) timescales. Most of my work has focused on the last full glacial-interglacial cycle, spanning roughly the past 130,000 years. Major variations in ocean circulation, from abyssal depths to the surface, are believed to have strongly influenced climate via the transport of heat. The oceans also exert control over atmospheric levels of carbon dioxide, an important "greenhouse" gas. Such changes are reflected in the physical and chemical properties of seawater, including temperature, salinity, the isotopic composition of dissolved inorganic carbon, and the concentrations of various nutrients. We use the calcitic shells of protozoa called foraminifera as recorders of these properties. By analyzing and dating sediment cores that contain foraminifera, we can reconstruct ocean chemistry and inferred circulation patterns during the past.

Selected Publications:

Bryan, S. P., and T. M. Marchitto, 2008, The Mg/Ca - temperature proxy in benthic foraminifera: New calibrations from the Florida Straits and a hypothesis regarding Mg/Li, Paleoceanography, 23(2), PA2220, doi:10.1029/2007PA001553, 2008.
Marchitto, T. M., S. J. Lehman, J. D. Ortiz, J. Flückiger, and A. van Geen, 2007, Marine radiocarbon evidence for the mechanism of deglacial atmospheric CO2 rise, Science, 316, 1456-1459, 2007.
Marchitto, T. M., and W. S. Broecker, 2006, 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.
Marchitto, T. M., J. Lynch-Stieglitz, and S. R. Hemming, 2005, Deep Pacific CaCO3 compensation and glacial-interglacial atmospheric CO2, Earth and Planetary Science Letters, 231, 317-336, 2005.
Marchitto, T. M., D. W. Oppo, and W. B. Curry, 2002, Paired benthic foraminiferal Cd/Ca and Zn/Ca evidence for a greatly increased presence of Southern Ocean Water in the glacial North Atlantic, Paleoceanography, 17(3), 1038, doi:10.1029/2000PA000598, 2002.
Koutavas, A., J. Lynch-Stieglitz, T. M. Marchitto, and J. P. Sachs, 2002, El Niño-like pattern in Ice Age tropical Pacific sea surface temperature, Science, 297, 226-230, 2002.
Marchitto, T. M., W. B. Curry, and D. W. Oppo, 1998, Millennial-scale changes in North Atlantic circulation since the last glaciation, Nature, 393, 557-561, 1998.

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