Tom Marchitto
- Professor
- Associate Director of Laboratories, INSTAAR
- Director, Trace Metal Laboratory
- GEOLOGICAL SCIENCES
- ATMOSPHERIC AND OCEANIC SCIENCES
Paleoceanography • Paleoclimatology • Geochemistry
As human activities continue to alter Earth’s climate, it becomes increasingly important to look to the past to better understand the future.
I am a paleoceanographer, studying large-scale changes in ocean circulation and biogeochemistry that occur over timescales ranging from a few years to millions of years. Major variations in ocean circulation, from the surface to abyssal depths, have influenced climate via the transport and storage 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, carbonate chemistry, radiocarbon age, and the concentrations of various nutrients. I use the chemistry of marine calcifiers, mainly foraminifera, as recorders of these properties.
I grew up in the geologically fascinating state of Connecticut, and was the first member of my family to attend college. Since collecting minerals and fossils were among my favorite hobbies, I decided to major in geology. I did undergraduate research with geochemist Karl Turekian and micropaleontologist Kuo-Yen Wei at Yale University. It was only natural to combine these two fields in my pursuit of a PhD in the MIT–Woods Hole Oceanographic Institution Joint Program. My principal advisors there were paleoceanographers Bill Curry and Delia Oppo, and Ed Boyle was also an important mentor. I then spent a bit over three years at the Lamont-Doherty Earth Observatory, working with a tremendous group of scientists that included my post-doctoral advisor Jean Lynch-Stieglitz, Lex van Geen, Peter deMenocal, Gerard Bond, Sidney Hemming, and Wally Broecker. I have been teaching at CU Boulder since 2003.
Diane McKnight and I are currently recruiting a PhD student to work on Colorado acid rock/mine drainage, with a start date in summer 2026. The first two years of this work are funded by the US Department of Energy in support of rare earth element recovery, in collaboration with the University of Missouri. Students may apply to CU Boulder either through Earth Science (formerly Geological Sciences) or through Environmental Studies.
Research interests
Past abrupt climate change, ocean circulation, ocean biogeochemistry, marine carbon cycle, trace and minor elements in biogenic calcium carbonates, biomineralization, acid rock/mine drainage.
Below are some of my recent research projects. I am also continually collaborating on multiple paleoceanographic studies spanning from the Pliocene to the Anthropocene.
PI: Anne Jennings; co-PIs: John Andrews, Alex Jahn, Tom Marchitto, Julio Sepulveda; Postdocs: Lineke Woelders, Hannah Zanowski
We are using numerical modeling and multi-proxy analyses of sediment cores from northern Baffin Bay to discover the timing and consequences of the Holocene (post-glacial) opening of the western gateway for Arctic freshwater to the Labrador Sea. We hypothesize that the establishment of this connection through the Canadian archipelago was important for the Atlantic meridional overturning circulation (AMOC) and the development of the North Water Polynya. Supported by NSF OPP Arctic Natural Sciences (2018-2021).
PI: Irina Overeem; co-PI: Tom Marchitto; PhD student: Ethan Pierce
The rapidly changing Greenland Ice Sheet supplies about 8% of the global riverine sediment flux to the ocean. Sediments rafted by icebergs might be an even greater flux, but constraints are poor. We are using field work, laboratory analysis, and numerical modeling to improve quantitative estimates of the modern fluxes of sediments and soluble iron (an important micronutrient) from Greenland icebergs. Supported by CU Boulder Research & Innovation Seed Grant (2018-2021).
Collaborative PIs: Edgar Lobaton, Tom Marchitto; co-PI: Michael Daniele
We are developing an autonomous sorting system for foraminifera, which will be accessible (in terms of usability and cost) to the scientific community. The automated identification of forams to the species level is accomplished using machine learning, developed under our prior NSF grant "A Visual System for Autonomous Foraminifera Identification." The current system makes use of micromanipulation and microfluidics to facilitate the transport of forams from a hopper to their sorted receptacles. Supported by NSF OCE Ocean Technology and Interdisciplinary Coordination (2016-2018 & 2019-2021).
Education
- PhD, Marine Geology and Geophysics, MIT-Woods Hole Oceanographic Institution Joint Program, 1999
- BS, Geology and Geophysics, Yale University, 1994
Awards
- College Scholar Award, University of Colorado Boulder, 2017 & 2024
- Kavli Frontiers of Science Fellow, National Academy of Sciences, 2013
- Provost's Faculty Achievement Award, University of Colorado Boulder, 2008
Current courses
- GEOL 5430: Paleoceanography and Paleoclimatology (alternate Falls) 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 other 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.
- GEOL 3070: Introduction to Oceanography (every Spring) Explores Earth's dynamic oceans. The course is roughly divided amongst the four main disciplines of oceanography: marine geology, marine chemistry, physical oceanography (i.e., circulation), and marine biology. Students will learn that there is much overlap and interdependence between these disciplines. Specific topics include seafloor spreading, marine sediments, salinity, biogeochemical cycles, ocean structure, currents, waves, tides, primary production, marine ecology, climate change, and much more.
- GEOL 4270/5270: Marine Chemistry and Geochemistry (alternate Falls) Examines the chemical, biological, geological, and physical processes affecting (and affected by) the chemistry of the oceans. Topics include: chemical speciation in seawater; the marine carbon cycle and its long-term control on atmospheric CO2; the large-scale interdependence of nutrient distributions and biological productivity; chemical tracers of ocean circulation; and the chemistry of marine sediments, including early diagenesis. Prereq., introductory geology and/or oceanography; CHEM 1111 General Chemistry or equivalent; comfort with algebra and calculus (differentials).
- GEOL 5705: Seminar in Paleoclimate (every Spring) Investigates major problems in the study and understanding of past climate variations as preserved in the geologic record. Course format is a seminar-style critical reading and discussion of journal articles in paleoclimatology and paleoceanography. Topical focus varies from year to year.
- GEOL 5701: Super-Problems in Quaternary Climate (Fall 2008, Spring 2010, Spring 2014) Investigates major problems in the study and understanding of Quaternary climate variation, in seminar format. Each year one major topic will be addressed, such as: the physics and chemistry of the ice age ocean circulation; the theory and mechanics of glacial/interglacial atmospheric CO2 change; or the origins of the 20, 40, and 100 kyr orbital (Milankovitch) climate cycles.
- GEOL 5420: Quaternary Dating Methods (Spring 2011) In-depth survey of standard and experimental dating methods that provide absolute ages for events of the last two million years of Earth history. Includes theory and application of radiocarbon, uranium series, amino acid, thermo-luminescence, fission track, potassium/argon, hydration, light stable isotopes, and other radioactive techniques. Prerequisites: Restricted to graduate students only.
Current students and postdocs
- Laurel Bayless, PhD Student (co-advised by Brad Markle)
- Daniele Callioni, BA Student Research Assistant and Bruce Curtis Mentee
- Amelia Fonda, BA Student Research Assistant and Bruce Curtis Mentee
- Jess Hankins, PhD Student
- Holly McCrory, BA Honors Student in Environmental Studies
- Adam Odorisio, MS Student in Environmental Engineering (co-advised by Diane McKnight)
- Trisia Tellez, PhD Student
Former postdocs
- Jody Wycech, CIRES Visiting Postdoctoral Fellow 2017-2019 (co-advised by Peter Molnar and Balaji Rajagopalan); US Geological Survey Petroleum Geochemistry Research Laboratory
- Lineke Woelders, ATOC & NSF Postdoc 2018-2019; CIRES Western Water Assessment
- Ritayan Mitra, NSF Postdoc 2016-2017; Indian Institute of Technology Bombay
- Kirstin Werner, German Academic Exchange Service Postdoctoral Fellow 2012-2013; University of Rostock
Former graduate students
- Athena Bolin, MS 2025 in Environmental Engineering (co-advised by Diane McKnight)
- Emily Roeder, MS 2021; US Air Force
- Brigitta Rongstad, PhD 2020; CIRES Communications
- Colin Lindsay, PhD 2016 (co-advised by Scott Lehman)
- Whitney Doss, PhD 2014; US Department of Energy
- Ursula Quillmann, PhD 2014 (co-advised by Anne Jennings); Colorado State University
- Hannah Grist, MS 2014; US Forest Service
- Sean Bryan, MS 2007, PhD 2010 (co-advised by Scott Lehman); Colorado State University
Former undergraduate honors thesis students
- Andres Reyes, Honors BA 2024
- Haikal Abu Bakar, Honors BA 2023
- Baylee Sergent, Honors BA 2020; Terracon Consultants
- Andrew Parker, Honors BA 2011; SPL
- Dan Lopez, Honors BA 2007