Biology & Paleo Environment Events

For upcoming seminars, see our calendar here.

Current Seminar Managers: Cassaundra Rose and Samuel Phelps 

Time and Location: Mondays at 12 pm, Comer Seminar Room

 SPECIAL SEMINARS Friday May 1st @ 9 am & 1:00 pm: Dr. Stephen Meyers, University of Wisconsin-Madison. Host: Maureen Raymo.

9 am, Comer: "Decoding climate rhythms with 'Astrochon: An R Package for Astrochronology.'”

Studies in paleoclimatology and cyclostratigraphy routinely utilize geologically preserved temporal rhythms – such as the Milankovitch cycles – to decipher mechanisms of climate change and to develop high-resolution/high-precision time scales. Statistical time series analysis provides the quantitative toolbox for the assessment of such rhythms. However, major challenges in cyclostratigraphic analysis include (1) the problem of searching for temporal rhythms in stratigraphic data for which the underlying time scale is poorly constrained, and (2) the development of null hypothesis tests that appropriately consider stochastic variability and distortion of the stratigraphic signal. In this talk, I will discuss recent advances in cyclostratigraphic analysis that address these challenges, and their implementation in 'Astrochron: An R Package for Astrochronology'.

Astrochron is a new software package that is a product of NSF award "CAREER: Deciphering the Beat of a Timeless Rhythm- The Future of Astrochronology". The software provides a robust statistical platform for the evaluation of astronomical-climate linkages, the development of astronomical time scales, and the integration of astrochronologies with other geochronologic/chronostratigraphic data (e.g., radioisotopic geochronology). An ultimate goal of the project is to facilitate efficient and transparent (open source) communication of the analytical approaches used, enabling rapid verification of results, and continual innovation through community involvement. To date, Astrochron contains over 70 functions, and has been a central component of four international workshops/summer schools.

1:00 pm, Comer: "Climate “Noise” and the Cryosphere: New Constraints on the Evolution of Ice Sheets During the Cenozoic."

The evolution of global climate during the past 34 million years is characterized by a transition from warm conditions with unipolar continental glaciation, to the bipolar ice sheets of the present. Much of our knowledge about the chronology of cryosphere development is based upon deep-sea benthic foraminiferal δ18O compilations that integrate global ice volume and regional deep ocean temperature. To deconvolve these mixed signals, the reconstruction of global ice volume typically requires the application of temperature proxy methods and/or global climate/ice-sheet models. These approaches have proven powerful, yet contribute their own uncertainty and ambiguity, particularly when the ice-volume signal is small. In this study we consider a novel means to constrain Cenozoic glaciation history through an assessment of the stochastic component of climate, using a new composite benthic δ18O record, noise parameter estimation, and quantitative sedimentation models. We demonstrate that the relatively long climate response time diagnostic of continental ice sheets is imparted upon observed stochastic benthic foraminiferal δ18O variability, and quantifiable using “noise response time” (NRT). Evaluation of changes in NRT using the new δ18O composite identifies the proposed Cenozoic glaciation (“Oi” and “Mi”) events – as well as some new events – and provides new evidence for their magnitudes. Overall, assessment of the δ18O composite within the context of stochastic variability provides unique insights into climate system history, complimenting the evaluation of astronomical forcing/pacing, and yielding new quantitative constraints on previously ambiguous aspects of cryosphere development during the Cenozoic.


May 4th: Dr. Suni Shah Walter, Harvard University. Host: Kim Popendorf.

"Lessons about microbe-mediated transformations of deep marine DOM from radiocarbon at the North Pond CORK site."


Near the Mid-Atlantic Ridge, at a site called the “North Pond”, deep ocean seawater circulates through the basaltic crust, supplying the aquifer-hosted microbial community with organic matter and electron acceptors. Studies have shown that these crustal fluids contain both oxygen and nitrate, potentially enabling a variety of microbial organic matter transformations that could have implications for the fate of dissolved organic matter from the deep ocean. Radiocarbon analysis of dissolved inorganic (DIC) and organic carbon (DOC) in fluids sampled from CORK (Circulation Obviation Retrofit Kit) observatories, show uncoupled “aging” between DOC and DIC with D14C values of DOC as low as -933 per mil. This D14C value, combined with reduced concentrations of DOC, resembles the modeled refractory DOC endmember, arguing for selective microbial oxidation of the younger, possibly more labile components of deep DOM in crustal aquifer environments.

Spring 2015:

  • February 2nd: Postponed due to winter storm
  • February 9th: Dr. Todd Sowers, Senior Scientist EESI, Penn State. Host: Pratigya Polissar. "Methane Isotope Records Spanning the last 160kyr: Correlations and Conundrums."
  • SPECIAL SEMINAR February 13th @ 1 pm: Dr. Matt Bekker, Brigham Young University. Host: Brendan Buckley. "Lessons from Centennial- and Millennial-length Reconstructions of Northern Utah’s Hydroclimate from Tree Rings."
  • February 16th: open
  • February 23rd: Dr. Lidya Tarhan, Postdoctoral Researcher, Yale University. Host: Cassaundra Rose. "Protracted Development of Bioturbation through the Early Paleozoic."
  • March 2nd, 2 pm: Dr. Christa Farmer, Hofstra. Host: Mike Kaplan. “Learning from the Impacts of Superstorm Sandy: Paleotempestology on Long Island.”
  • March 9th: Dr. Carling Hay, Postdoctoral Fellow, Harvard University. Host: Maureen Raymo. "Revisiting the Past: Fingerprinting the Sources of 20th Century Global Sea-Level Rise."
  • March 16th: open/Spring Break
  • March 23rd: Dr. Ailene Ettinger, Putnam Fellow, The Arnold Arboretum of Harvard University. Host: Ben Cook. "Testing the limits: effects of climate & competition on tree ranges in a warming world"
  • March 30th: Dr. Steven Smriga, MIT. Host: Andrew Juhl. "Dissecting the Phycosphere: Upscaling Bacterial Consumption Near Individual Diatoms."
  • April 6th: Dr. Jodi Young, Postdoctoral Researcher, Princeton University. Host: Kim Popendorf. "Physiological mechanisms supporting high net primary productivity in the Western Antarctic Peninsula."
  • SPECIAL SEMINAR April 6th, 2:30 p.m.: Dr. Erik Cordes, Associate Professor, Temple University. Host: Andy Juhl. "Understanding the Deep Sea in the Anthropocene: Oil spills and ocean acidification threaten deep-water corals in the Gulf of Mexico."
  • April 13th, 2 pm: Dr. Mrinalini Nikrad, Postdoc, Rutgers. Host: Jeff Bowman. "Microbial response to changing climate in sub-zero ocean and soil ecosystems."
  • April 20th: Dr. Aldo Shemesh, Weizmann Institute. Host: Yoni Goldsmith. "Recent unprecedented state of eastern Mediterranean Sea within the last millennium."
  • April 27th: Dr. Jennifer Stanford, Drexel University. Host: Andy Juhl. "Changing How We Teach: Evidence-Based Approaches to Promote STEM Student Retention."
  • SPECIAL SEMINAR May 1st @ 9 am & 1:00 pm: Dr. Steven Meyers. Host: Maureen Raymo.
    • 9 am: Decoding climate rhythms with “Astrochon: An R Package for Astrochronology”
    • 1 pm: "Climate “Noise” and the Cryosphere: New Constraints on the Evolution of Ice Sheets During the Cenozoic."
  • May 4th: Dr. Suni Shah Walter, Harvard University. Host: Kim Popendorf. "Lessons about microbe-mediated transformations of deep marine DOM from radiocarbon at the North Pond CORK site."
  • May 11th: Dr. Jack Scheff, Postdoc, LDEO, "Does greenhouse warming dry out the continents? Lessons from theory, proxies, and models"
  • May 18th: Dr. Brad Linsley, LDEO. American Samoa coral record of S. Pacific climate
  • June 1st: Dr. Navjit Sagoo, Postdoctoral Associate, Yale University. Host: Frankie Pavia. Tentative topic: dust and cloud physics in the Pliocene

Additional talks can be seen on the

google calendar.