Climate of the Past Discussions www.clim-past-discuss.net 1814-9340 1814-9359 5 1 2009 10.5194/cpd-5-237-2009 http://www.clim-past-discuss.net/5/237/2009/ http://www.clim-past-discuss.net/5/237/2009/cpd-5-237-2009.html http://www.clim-past-discuss.net/5/237/2009/cpd-5-237-2009.pdf 237 250 2009-01-21 Pleistocene glacial variability as a chaotic response to obliquity forcing P. Huybers phuybers@fas.harvard.edu Department of Earth and Planetary Sciences, Harvard University, Cambridge MA, USA The mid-Pleistocene transition from 40 ky to ~100 ky glacial cycles is generally characterized as a singular transition attributable to scouring of continental regolith or a long-term decrease in atmospheric CO₂ concentrations. Here an alternative hypothesis is suggested, that Pleistocene glacial variability is chaotic and that transitions from 40 ky to ~100 ky modes of variability occur spontaneously. 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