Preprints
https://doi.org/10.5194/cp-2021-103
https://doi.org/10.5194/cp-2021-103

  11 Aug 2021

11 Aug 2021

Review status: this preprint is currently under review for the journal CP.

Abrupt climate changes and the astronomical theory

Denis-Didier Rousseau1,2, Witold Bagniewski3, and Michael Ghil3,4 Denis-Didier Rousseau et al.
  • 1Geosciences Montpellier, University Montpellier, CNRS, Montpellier, France
  • 2Lamont-Doherty Earth Observatory, Columbia University, New York, 10964, USA
  • 3Laboratoire de Météorologie Dynamique (Institut Pierre Simon Laplace and CNRS), Ecole Normale Supérieure and PSL University, Paris, France
  • 4Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles, CA 90095, USA

Abstract. Abrupt climate changes constitute a relatively new field of research, which addresses variations occurring in a relatively short time interval of tens to a hundred years. Such time scales do not correspond to the tens or hundreds of thousands of years that the astronomical theory of climate addresses. The latter theory involves parameters that are external to the climate system and whose multi-periodic variations are reliably known and almost constant for a large extent of Earth history. Abrupt changes, conversely, appear to involve fast processes that are internal to the climate system; these processes varied considerably during the past 2.6 Myr, and yielded more irregular fluctuations. In this paper, we re-examine the main climate variations determined from the U1308 North Atlantic marine record, which yields a detailed calving history of the Northern Hemisphere ice sheets over the past 3.2 Myr. The magnitude and periodicity of the ice-rafted debris (IRD) events observed in the U1308 record allow one to determine the timing of several abrupt climate changes, the larger ones corresponding to the massive iceberg discharges labeled Heinrich events (HEs). In parallel, abrupt warmings, called Dansgaard-Oeschger (DO) events, have been identified in the Greenland records of the last glaciation cycle. Combining the HE and DO observations, we study a complex mechanism that may lead to the observed millennial-scale variability corresponding to the abrupt climate changes of last 0.9 Myr. This mechanism relies on amended Bond cycles, which group DO events and the associated Greenland stadials into a trend of increased cooling, with IRD events embedded into every stadial, the latest of these being an HE. These Bond cycles may have occurred during the last 0.9 Ma when Northern Hemisphere ice sheets reached their maximum extent and volume, thus becoming a major player in this time interval’s climate dynamics. Since the waxing and waning of ice sheets during the Quaternary period are orbitally paced, we conclude that the abrupt climate changes observed during the Mid and Upper Pleistocene are therewith indirectly linked to the astronomical theory of climate.

Denis-Didier Rousseau et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on cp-2021-103', Anonymous Referee #1, 14 Sep 2021
    • AC1: 'Reply on RC1', Denis-Didier Rousseau, 20 Sep 2021
    • AC4: 'Reply on RC1', Denis-Didier Rousseau, 20 Oct 2021
  • RC2: 'Review of Rousseau et al.', Anonymous Referee #2, 14 Sep 2021
    • AC2: 'Reply on RC2', Denis-Didier Rousseau, 20 Sep 2021
    • AC5: 'Reply on RC2', Denis-Didier Rousseau, 21 Oct 2021
  • RC3: 'Comment on cp-2021-103', Linda A. Hinnov, 11 Oct 2021
    • AC3: 'Reply on RC3', Denis-Didier Rousseau, 15 Oct 2021
    • AC6: 'Reply on RC3', Denis-Didier Rousseau, 22 Oct 2021
  • EC1: 'Additional comments to RC3', Marie-France Loutre, 12 Oct 2021
  • EC2: 'Additional comments to RC3', Marie-France Loutre, 12 Oct 2021

Denis-Didier Rousseau et al.

Denis-Didier Rousseau et al.

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Short summary
Abrupt climate changes constitute a relatively new field of research, which addresses variations occurring in a relatively short time interval of tens to a hundred years. Such time scales do not correspond to the tens or hundreds of thousands of years that the astronomical theory of climate addresses. Revisiting some key records of the past 3.2 Myr, we show that nevertheless, the millennial scale abrupt climate changes are indirectly linked to the astronomical theory of climate.