The 8.2 ka event in northern Spain: timing, structure and climatic impact from a multi-proxy speleothem record

• Published in: Climate of the Past
• Main Authors: Kilhavn, Hege, Couchoud, Isabelle, Drysdale, Russell, N, Rossi, Carlos, Hellstrom, John, Arnaud, Fabien, Wong, Henri
• Other Authors: Environnements, Dynamiques et Territoires de Montagne (EDYTEM), Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS), School of Geography, Earth and Atmospheric Sciences Melbourne, University of Melbourne, School of Geography Melbourne, Faculty of Science Melbourne, University of Melbourne-University of Melbourne, Universidad Complutense de Madrid = Complutense University of Madrid Madrid (UCM), School of Earth Sciences Melbourne, Australian Nuclear Science and Technology Organisation Australie (ANSTO)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2022
• Subjects: [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces; environment; [SDE.MCG]Environmental Sciences/Global Changes; [SDE.ES]Environmental Sciences/Environment and Society; Greenland; Greenland ice core; ice core; North Atlantic
• Online Access: https://hal.science/hal-03868874; https://hal.science/hal-03868874/document; https://hal.science/hal-03868874/file/cp-18-2321-2022.pdf; https://doi.org/10.5194/cp-18-2321-2022

International audience The 8.2 ka event is regarded as the most prominent climate anomaly of the Holocene and is thought to have been triggered by a meltwater release to the North Atlantic that was of sufficient magnitude to disrupt the Atlantic Meridional Overturning Circulation (AMOC). It is most clearly captured in Greenland ice-core records, where it is reported as a cold and dry anomaly lasting ∼ 160 years, from 8.25 ± 0.05 until 8.09 ± 0.05 ka (Thomas et al., 2007). It is also recorded in several archives in the North Atlantic region; however, its interpreted timing, evolution and impacts vary significantly. This inconsistency is commonly attributed to poorly constrained chronologies and/or inadequately resolved time series. Here we present a highresolution speleothem record of early Holocene palaeoclimate from El Soplao Cave in northern Spain, a region pertinent to studying the impacts of AMOC perturbations on southwestern Europe. We explore the timing and impact of the 8.2 ka event on a decadal scale by coupling speleothem stable carbon and oxygen isotopic ratios, trace element ratios (Mg / Ca and Sr / Ca), and growth rate. Throughout the entire speleothem record, δ 18 O variability is related to changes in effective recharge. This is supported by the pattern of changes in δ 13 C, Mg / Ca and growth rate. The 8.2 ka event is marked as a centennial-scale negative excursion in El Soplao δ 18 O, starting at 8.19 ± 0.06 ka and lasting until 8.05 ± 0.05 ka, suggesting increased recharge at the time. Although this is supported by the other proxies, the amplitude of the changes is minor and largely within the realm of variability over the preceding 1000 years. Further, the shift to lower δ 18 O leads the other proxies, which we interpret as the imprint of the change in the isotopic composition of the moisture source, associated with the meltwater flux to the North Atlantic. A comparison with other well-dated records from southwestern Europe reveals that the timing of the 8.2 ka event was synchronous, with an ...