Preprints
https://doi.org/10.5194/cp-2022-1
https://doi.org/10.5194/cp-2022-1
 
17 Jan 2022
17 Jan 2022
Status: this preprint is currently under review for the journal CP.

Ice core evidence for major volcanic eruptions at the onset of Dansgaard-Oeschger warming events

Johannes Lohmann and Anders Svensson Johannes Lohmann and Anders Svensson
  • Physics of Ice, Climate and Earth, Niels Bohr Institute, University of Copenhagen, Denmark

Abstract. A significant influence of major volcanic eruptions on regime shifts and long-term climate variability has been suggested previously. But a statistical assessment of this has been hampered by inaccurate synchronization of large volcanic eruptions to changes in past climate. Here, this is achieved by combining a new record of bipolar volcanism from Greenland and Antarctic ice cores with records of abrupt climate change derived from the same ice cores. We show that bipolar volcanic eruptions occurred significantly more frequently than expected by chance just before the onset of Dansgaard-Oeschger events, the most prominent large-scale abrupt climate changes of the last glacial period. Out of 20 abrupt warming events in the 12–60 ka period, 5 (7) occur within 20 (50) years after a bipolar eruption. A similar statistical relationship is not found for eruptions before the abrupt cooling phases of the Dansgaard-Oeschger cycles. We hypothesize that this asymmetric response to volcanic eruptions may be a result of the direct influence of volcanic cooling on the Atlantic meridional overturning circulation, which is widely regarded as the main climate subsystem involved in Dansgaard-Oeschger cycles. Transitions from a weak to a strong circulation mode, but not vice versa, may be triggered by cooling in the North Atlantic, given the circulation is close to a stability threshold. We illustrate this suggestion by simulations with a global ocean model forced by short-term volcanic cooling. The analysis presented suggests that large eruptions may act as short-term triggers for large-scale abrupt climate change, and may explain part of the variability of Dansgaard-Oeschger cycles.

Johannes Lohmann and Anders Svensson

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-2022-1', Anonymous Referee #1, 09 Feb 2022
    • AC1: 'Reply on RC1', Johannes Lohmann, 22 Apr 2022
  • RC2: 'Comment on cp-2022-1', Anonymous Referee #2, 25 Feb 2022
    • AC2: 'Reply on RC2', Johannes Lohmann, 22 Apr 2022
  • RC3: 'Comment on cp-2022-1', Anonymous Referee #3, 16 Mar 2022
    • AC3: 'Reply on RC3', Johannes Lohmann, 22 Apr 2022
  • RC4: 'Review of Lohmann and Svenssonmment', Anonymous Referee #4, 21 Mar 2022
    • RC5: 'Reply on RC4', Anonymous Referee #3, 21 Mar 2022
      • AC5: 'Reply on RC5', Johannes Lohmann, 22 Apr 2022
    • AC4: 'Reply on RC4', Johannes Lohmann, 22 Apr 2022

Johannes Lohmann and Anders Svensson

Johannes Lohmann and Anders Svensson

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Latest update: 20 May 2022
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Short summary
Major volcanic eruptions are known to cause considerable short-term impacts on the global climate. Their influence on long-term climate variability and regime shifts is less well understood. Here we show that very large, bipolar eruptions occurred more frequently than expected by chance just before abrupt climate change events in the last glacial period (the Dansgaard-Oeschger events). Thus, such large eruptions may in some cases act as short-term triggers to abrupt regime shifts of the climate.