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dc.contributor.authorHuybers, Peter
dc.date.accessioned2009-08-13T13:28:33Z
dc.date.issued2007
dc.identifier.citationHuybers, Peter. 2007. Glacial variability over the last two million years: An extended depth-derived agemodel, continuous obliquity pacing, and the Pleistocene progression. Quaternary Science Reviews 26(1-2): 37-55.en
dc.identifier.issn0277-3791en
dc.identifier.urihttp://nrs.harvard.edu/urn-3:HUL.InstRepos:3207710
dc.description.abstractAn agemodel not relying upon orbital assumptions is estimated over the last 2 Ma using depth in marine sediment cores as a proxy for time. Agemodel uncertainty averages +/- 10 Ka in the early Pleistocene (similar to 2-1 Ma) and +/- 7 Ka in the late Pleistocene (similar to 1 Ma to the present). Twelve benthic and five planktic delta O-18 records are pinned to the agemodel and averaged together to provide a record of glacial variability. Major deglaciation features are identified over the last 2 Ma and a remarkable 33 out of 36 occur when Earth's obliquity is anomalously large. During the early Pleistocene deglaciations occur nearly every obliquity cycle giving a 40 Ka timescale, while late Pleistocene deglaciations more often skip one or two obliquity beats, corresponding to 80 or 120 Ka glacial cycles which, on average, give the similar to 100 Ka variability. This continuous obliquity pacing indicates that the glacial theory can be simplified. An explanation for the similar to 100 Ka glacial cycles only requires a change in the likelihood of skipping an obliquity cycle, rather than new sources of long-period variability. Furthermore, changes in glacial variability are not marked by any single transition so much as they exhibit a steady progression over the entire Pleistocene. The mean, variance, skewness, and timescale associated with the glacial cycles all exhibit an approximately linear trend over the last 2 Ma. A simple model having an obliquity modulated threshold and only three adjustable parameters is shown to reproduce the trends, timing, and spectral evolution associated with the Pleistocene glacial variability.en
dc.description.sponsorshipEarth and Planetary Sciencesen
dc.language.isoen_USen
dc.publisherElsevieren
dc.relation.isversionofhttp://dx.doi.org/10.1016/j.quascirev.2006.07.013en
dc.relation.hasversionhttp://www.people.fas.harvard.edu/~phuybers/Progression/Progression.pdfen
dash.licenseLAA
dc.subjectgeochronologyen
dc.subjecthypothesis testen
dc.subjectmid-Pleistocene transitionen
dc.subjectglacial cyclesen
dc.subjectorbital forcingen
dc.subjectobliquityen
dc.titleGlacial Variability Over the Last Two Million Years: An Extended Depth-Derived Agemodel, Continuous Obliquity Pacing, and the Pleistocene Progressionen
dc.relation.journalQuaternary Science Reviewsen
dash.depositing.authorHuybers, Peter
dc.identifier.doi10.1016/j.quascirev.2006.07.013*
dash.contributor.affiliatedHuybers, Peter


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