Multiple instabilities and modes of glacial rhythmicity in the Plio-Pleistocene: A general theory of late Cenozoic climatic change

Journal Article · Fri Oct 01 04:00:00 EDT 1993 · Climate Dynamics

DOI:https://doi.org/10.1007/BF00208010· OSTI ID:258854

Saltzman, B; Verbitsky, M Ya ^[1]

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1. Yale Univ., New Haven, CT (United States)

Several distinct modes of glacial oscillation have existed during the past few million years, ranging from low-amplitude, high-frequency oscillations in the early Pliocene, through relatively high amplitude, predominantly near 40 ky period, oscillations in the late Pliocene and early Pleistocene, to the major near 100 ky period oscillations of the late Pleistocene. In addition to other plausible mechanisms, this study illustrates another possible contributor based on the hypothesis that the slow-response climatic system is bistable and that two kinds of internal instability may be operative along with externally imposed forcing due to earth-orbital (Milankovitch) radiation changes and slow, tectonically-induced changes in atmospheric carbon dioxide. Within the framework of a dynamical model containing the possibility for these two instabilities, as well as for stable modes, the study shows (1) how Milankovitch radiative changes or stochastic forcing influencing ice sheets can induce aperiodic (chaotic) transitions between the possible stable and unstable modes, and (2) how progressive, long-term, tectonically-induced, changes in carbon dioxide, acting in concert with earth-orbital radiative variations in high Northern Hemisphere latitudes, can force systematic transitions between the modes. This is a minimum dynamical model of the late Cenozoic climatic changes, containing the main physical factors determining these changes: ice mass, bedrock depression, atmospheric carbon dioxide concentration, deep ocean thermohaline state, Milankovitch radiation forcing, and slow tectonically-induced carbon dioxide forcing. 34 refs., 13 figs., 2 tabs.

• Sponsoring Organization: USDOE
• OSTI ID: 258854
• Journal Information: Climate Dynamics, Journal Name: Climate Dynamics Journal Issue: 1 Vol. 9; ISSN 0930-7575; ISSN CLDYEM
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
CENOZOIC ERA
CLIMATE MODELS
GLACIERS
PALEOCLIMATOLOGY