Plio–Pleistocene climate evolution: trends and transitions in glacial cycle dynamics |
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| Institution: | 1. Institute of Earth Sciences, Heidelberg University, Im Neuenheimer Feld 234-236, 69120, Heidelberg, Germany;2. Institute of Earth Sciences, University of Frankfurt, Altenhöferallee 1, 60438, Frankfurt, Germany;3. Department of Geosciences, National Taiwan University, Roosevelt Road, 106, Taipei, Taiwan, ROC;4. Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge, Cambridgeshire, CB2 3EQ, UK;5. PSL, IMCCE, Observatoire de Paris, 77 Av. Denfert-Rochereau, F-75014, Paris, France;1. British Antarctic Survey, Ice Cores, Cambridge CB3 0ET, UK;2. Simon Fraser University, 8888 University Drive, Burnaby V5A 1S6, Canada;3. School of Environmental Sciences, University of East Anglia, Norwich NR4 7TJ, UK;4. Department of Geological Sciences, Stockholm University, 106 91 Stockholm, Sweden;5. Centre National de la Recherche Scientifique, CEA, Saclay 91191, France;1. School of Ocean and Earth Science, National Oceanography Centre, University of Southampton, Southampton SO14 3ZH, United Kingdom;2. Department of Geological Sciences, Brown University, Providence, RI, USA;3. Center for Advanced Marine Core Research, Kochi University, Kochi, Japan;1. Utrecht University, Faculty of Geosciences, Postbus 80.115, 3508 TC, Utrecht, The Netherlands;2. School of Earth Sciences and Environmental Sustainability, Northern Arizona University, Flagstaff, AZ, USA;3. School of Earth and Environment, University of Leeds, Leeds, LS2 9JT, UK;4. Royal Netherlands Meteorological Institute, Postbus 201, 3730 AE, De Bilt, The Netherlands;1. Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY, USA;2. Department of Earth and Environmental Sciences, Columbia University, New York, NY, USA;3. Department of Earth and Ocean Dynamics, University of Barcelona, Barcelona, Spain;4. Max-Planck Institut für Chemie, Mainz, Germany |
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| Abstract: | We describe the evolution of climate system dynamics by examining the climate response to changes in obliquity and precession over the last 5.3 Myr. In particular, we examine changes in the shape of glacial cycles and the power of obliquity and precession response in benthic δ18O. When the exponential trend in δ18O variance is removed, its spectral power exhibits strong, proportional responses to amplitude modulations in orbital forcing over most of the Plio–Pleistocene. Precession responses correlate with modulations in forcing for the last 5 Myr, but 41-kyr response is sensitive to obliquity modulation only before 1.4 Myr. Where responses are sensitive to modulations in forcing, we demonstrate that glacial cycles are orbitally forced rather than being self-sustained or paced by orbital changes. The shapes of glacial cycles have several nonlinear properties, which may be indicative of glacial–interglacial differences in climate sensitivity or response time. The “saw-tooth” asymmetry of glacial cycles first appears shortly after the onset of major northern hemisphere glaciation, and the relative duration of interglacial stages decreases at 1.4 Myr. Collectively, trends in the shape of glacial cycles and the sensitivity of δ18O to obliquity and precession are suggestive of major transitions in climate dynamics at approximately 2.5 and 1.4 Myr but show no significant change associated with the appearance of strong 100-kyr cycles during the mid-Pleistocene transition. |
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