Fall 2016

Climate Center Lecturers

DATES: September 12 - 16, 2016
Stephen Meyers

Associate Professor, University of Wisconsin-Madison
Department of Geoscience 1215 W. Dayton St. Madison, WI 53796
Phone: 608-890-2574 FAX: 608-262-0693
email: smeyers@geology.wisc.edu - http://www.geology.wisc.edu/~smeyers/

If you wish to meet with Prof. Meyers, please contact the Administrator at clmtctr@ldeo.columbia.edu directly.

Prof. Meyers will be giving two lectures on the LDEO Campus and one on the GISS/NASA Campus; all three lectures plus the reception are open to all. You must register for the one held at GISS.


Monday, September 12, 2013 - 12:00PM BPE Seminar- Comer 1st Floor Seminar Room,  -

Evolution of the Climate Continuum: A New Approach for Constraining Cenozoic Ice Sheet History 

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. Numerous geochemical, stratigraphic, and modeling approaches have been utilized to evaluate this history – with varying success – but there remain critical uncertainties about the timing and magnitude of cryosphere development. In this study we develop a novel means to constrain Cenozoic glaciation history, through an assessment of stochastic variability (the “spectral continuum”) that is omnipresent in climate proxy data.  Using quantitative sedimentation models and a new composite benthic δ18O record, we demonstrate that the relatively long climate response time diagnostic of continental ice sheets is reliably imparted upon observed stochastic benthic foraminiferal δ18O variability, and quantifiable using “noise response time”. Analysis of δ18O noise response time identifies all known and several new glaciation events, and demonstrates increasing ice sheet volatility following a decline in atmospheric pCO2 at ~23 Ma. This assessment provides quantitative constraints on the timing and magnitude of cryosphere development during the Cenozoic, including a new predictive tool for the evaluation of cryptic glaciation events, complimenting prior studies that focus on astronomical forcing/pacing.

Wednesday, September 14, 2016 - 11:30AM Columbia Climate Center Lecture- Monell Auditorium, Reception to Follow -

Being Milankovitch

When Milankovitch cycles are preserved in the geologic record, they provide a direct link between chronometer and climate change, and thus a remarkable opportunity to constrain the evolution of the surficial Earth System. Consequently, the identification of such cycles has allowed exploration of the geologic record with unprecedented temporal resolution, and has spurred the development of a rich theoretical framework for climatic change. 

Accompanying these successes, however, has been a persistent skepticism: how does one reliably test for astronomical forcing/pacing in paleoclimate data, especially when time is poorly constrained? From this perspective, it would seem that the merits and promise of astrochronology – a Phanerozoic time scale measured in 20,000 to 400,000 year increments – also serves as its Achilles heel, if the confirmation of such temporal rhythms defies rigorous statistical testing. The implications are substantial, since much of our understanding of paleoclimate change throughout the past 60 million years (and beyond) is firmly rooted in the supposition of accurate astrochronologies. 

In this talk, I will present a conceptual framework for assessing Earth System response to astronomical-insolation changes and the propagation of that signal into the geologic record. This framework motivates the development of a new approach for astrochronologic testing, which evaluates time scale uncertainty while simultaneously identifying the optimal model for climate and depositional system response to astronomical forcing. The technique explicitly reconstructs distortions of the primary forcing that are known to be omnipresent in the stratigraphic record. Application of this new method to paleoclimate records throughout the Phanerozoic illuminates what it means to “be Milankovitch”, and yields new constraints on the evolution of the Solar System and the astronomical solutions themselves.


Thursday, September 15, 2016 - 11:00AM NASA GISS Armstrong Hall 3rd Floor Conference Room - Being Milankovitch . *Please be sure to bring your valid state-issued ID.  Everyone needs to preregister with allegra.n.legrande@nasa.gov