I am a paleoclimatologist who uses the geologic record to decipher the patterns and mechanisms of past changes in climate and ice sheets on decade to million year time scales. This research is guided by a series of overarching questions - how sensitive is the climate to external forcings, how are various regions and components of the climate system linked, and how well do models simulate the past? My research group applies various tools to address these questions, including developing geochemical records from several paleo-archives (glacier, marine, and cave deposits), and mining the growing body of paleoclimate datasets to search for large-scale patterns. These approaches can entail work behind the computer, in various collaborators' labs, and in the field from places as far off as the Arctic or as close as New England. I'm particularly motivated by paleoclimate problems that have clear relevance to today.
CURRENT GRADUATE STUDENTS AND PROJECTS
- Danielle LeBlanc: Using cosmogenic nuclides in ice-rafted debris to constrain ice sheet dynamics associated with Heinrich events (M.S.)
- Drew Gorin: Holocene glacier length variations along the spine of the American Cordilleras and their climatic significance (M.S.)
RECENT M.S. ALUMNI AND PROJECTS
- Celeste Gambino: A uranium-lead chronology of speleothem deposition in the Canadian Arctic (M.S., 2018)
- Chris Halsted: Determining the Timing and Rate of Laurentide Ice Sheet Thinning During the Last Deglaciation in New England with 10Be Dipsticks (M.S., 2018)
- Cole Vickers: Tropical Andean and African glacier extent through the Holocene assessed with proglacial in situ 14C and 10Be measurements (M.S., 2018)
- Nikki Biller: Widespread permafrost thaw during Marine Isotope Stage 11 recorded by speleothems (M.S., 2017)
- Allie Koester: Rapid thinning of the Laurentide Ice Sheet in coastal Maine during late Heinrich Stadial 1 (M.S., 2017)
SELECTED RECENT PUBLICATIONS (*BC student co-authors)
- Marcott, S. A., Clark, P. U., Shakun, J. D., Brook, E. J., Davis, P. T., Caffee, M. W. (2019). 10Be age constraints on latest Pleistocene and Holocene cirque glaciation across the western United States. npj Climate and Atmospheric Science, https://doi.org/10.1038/s41612-019-0062-z.
- Shakun, J. D., Corbett, L. B., Bierman, P. R., Underwood, K., Rizzo, D., Zimmerman, S. R., Caffee, M. W., Naish, T., Golledge, N, and Hay, C. (2018). Minimal East Antarctic Ice Sheet retreat onto land during the past eight million years. Nature, 558, https://doi.org/10.1038/s41586-018-0155-6.
- *Koester, A., Shakun, J.D., Bierman, P.R., Davis, P.T., Corbett, L.B., Braun, D., and Zimmerman, S. (2017). Rapid thinning of the Laurentide Ice Sheet in coastal Maine during late Heinrich Stadial 1. Quaternary Science Reviews, 163, https://doi.org/10.1016/j.quascirev.2017.03.005.
- Bierman, P. R., Shakun, J. D., Corbett, L. B., Rood, D. H., and Zimmerman, S. (2016). A persistent and dynamic East Greenland Ice Sheet over the past 7.5 million years. Nature, 540, https://doi.org/10.1038/nature20147.
- Shakun, J. D., Raymo, M. E., and Lea, D. W. (2016). An early Pleistocene Mg/Ca-δ18O record from the Gulf of Mexico: Evaluating ice sheet size and pacing in the 41-kyr world. Paleoceanography, https://doi.org/10.1002/2016PA002956.