EGU2020-3103
https://doi.org/10.5194/egusphere-egu2020-3103
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Late Holocene thermohaline perturbation of the N-Atlantic Subpolar Gyre linked to exceptional Greenland Ice Sheet melting between 4.4 and 4.0 ka BP

Antoon Kuijpers1, Marit-Solveig Seidenkrantz2, Ralph Schneider3, Camilla S. Andresen1, Signe Hygom Jacobsen2, Mimmi Oksman1, Lisa C. Orme4, Jian Ren5, and Sandrine Solignac6
Antoon Kuijpers et al.
  • 1Geological Survey of Denmark and Greenland, Dept. Glaciology & Climate, 1350 Copenhagen K, Denmark
  • 2Centre for Past Climate Studies, Department of Earth Sciences, Aarhus University, 8000 Aarhus C, Denmark
  • 3Institute of Geosciences, Kiel University, 24118 Kiel, Germany
  • 4ICARUS, Department of Geography, Maynooth University, W23 Maynooth, Ireland
  • 5Second Institute of Oceanography SOA, Key Laboratory of Marine Ecosystem and Biogeochemistry, Hangzhou, China
  • 6Geotop, Université du Québec à Montréal, CP 8888, succ.Centre-Ville Montréal, Québec, H3C3P8 Canada

Knowledge of the impact of past climate warming on Greenland Ice Sheet stability is an important issue for assessing  thresholds that are critical for a potential ice sheet collapse. For the late Holocene, evidence has recently been found of a so-called 4.2 ka BP event(1) including a prominent warming spike in several ice core records from Greenland and Canada (Agassiz).  Also lake records from both Northwest(2) and South Greenland(3) support pronounced summer warming during that time. After c. 4.0 ka BP NW Greenland July air temperature dropped by about 3o C. Coeval with this exceptional atmospheric warming anomaly over northern Canada and parts of Greenland, abrupt cooling and freshening affected  the N-Atlantic subpolar gyre where Labrador Sea deep convection ceased(4). Northern N-Atlantic climate generally deteriorated. With our contribution we present Holocene sub-bottom profiling  and sedimentary shelf and  fjord records from Southwest Greenland and Disko Bay that indicate exceptional Greenland Ice Sheet melting 4.4-4.0 ka BP at a rate and magnitude not recorded since early Holocene deglaciation. Extremely strong melt water discharge resulted in erosion of fjord sediments(5) and local deposition of up to several meters thick meltwater sediment on the shelf(6-8).  Timing of this melting event corresponds to a significant anomaly in hydrographic parameters of the Labrador Current off Newfoundland(9,10), which is concluded to have resulted in thermohaline perturbation of the N-Atlantic Subpolar gyre.   

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How to cite: Kuijpers, A., Seidenkrantz, M.-S., Schneider, R., S. Andresen, C., Hygom Jacobsen, S., Oksman, M., C. Orme, L., Ren, J., and Solignac, S.: Late Holocene thermohaline perturbation of the N-Atlantic Subpolar Gyre linked to exceptional Greenland Ice Sheet melting between 4.4 and 4.0 ka BP , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3103, https://doi.org/10.5194/egusphere-egu2020-3103, 2020