TY - JOUR

T1 - Ice core evidence for major volcanic eruptions at the onset of Dansgaard-Oeschger warming events

AU - Lohmann, Johannes

AU - Svensson, Anders

PY - 2022/9/2

Y1 - 2022/9/2

N2 - While a significant influence of volcanic activity on Holocene climate is well-established, an equally prominent role of major eruptions in the climate variability and regime shifts during the Quaternary glacial cycles has been suggested. Previous statistical assessments of this were challenged by inaccurate synchronization of large volcanic eruptions to changes in past climate. Here, this is alleviated 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, which are the most prominent large-scale abrupt climate changes in 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. We hypothesize that this 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 may be triggered by cooling in the North Atlantic given that the circulation is close to a stability threshold. We illustrate this suggestion by simulations with an ocean-only general circulation 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 some of the variability of Dansgaard-Oeschger cycles. While we argue that the bipolar catalogue used here covers a sufficiently large portion of the eruptions with the strongest global climate impact, volcanic events restricted to either the Northern or Southern Hemisphere may likewise contribute to abrupt climate change.

AB - While a significant influence of volcanic activity on Holocene climate is well-established, an equally prominent role of major eruptions in the climate variability and regime shifts during the Quaternary glacial cycles has been suggested. Previous statistical assessments of this were challenged by inaccurate synchronization of large volcanic eruptions to changes in past climate. Here, this is alleviated 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, which are the most prominent large-scale abrupt climate changes in 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. We hypothesize that this 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 may be triggered by cooling in the North Atlantic given that the circulation is close to a stability threshold. We illustrate this suggestion by simulations with an ocean-only general circulation 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 some of the variability of Dansgaard-Oeschger cycles. While we argue that the bipolar catalogue used here covers a sufficiently large portion of the eruptions with the strongest global climate impact, volcanic events restricted to either the Northern or Southern Hemisphere may likewise contribute to abrupt climate change.

KW - MERIDIONAL OVERTURNING CIRCULATION

KW - ABRUPT CLIMATE-CHANGE

KW - LAST GLACIAL PERIOD

KW - ATLANTIC-OCEAN

KW - GREENLAND

KW - LATITUDE

KW - RECORDS

KW - IMPACT

KW - INSTABILITY

KW - MAGNITUDE

U2 - 10.5194/cp-18-2021-2022

DO - 10.5194/cp-18-2021-2022

M3 - Journal article

VL - 18

SP - 2021

EP - 2043

JO - Climate of the Past

JF - Climate of the Past

SN - 1814-9324

IS - 9

ER -