EGU2020-1353
https://doi.org/10.5194/egusphere-egu2020-1353
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Northern Sourced Water dominated the Atlantic Ocean during the Last Glacial Maximum

Frerk Pöppelmeier1,2, Patrick Blaser1, Marcus Gutjahr3, Samuel Jaccard4, Martin Frank3, Lars Max5, and Jörg Lippold1
Frerk Pöppelmeier et al.
  • 1Institute of Earth Sciences, Heidelberg University, Heidelberg, Germany (frerk.poeppelmeier@geow.uni-heidelberg.de)
  • 2Climate and Environmental Physics - Physics Institute, University of Bern, Bern, Switzerland
  • 3GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
  • 4Institute of Geological Sciences and Oeschger Center for Climate Change Research, University of Bern, Switzerland
  • 5MARUM-Center for Marine Environmental Sciences, University of Bremen, Germany

Increased carbon sequestration in the ocean subsurface is commonly assumed to have been one of the main causes responsible for lower glacial atmospheric CO2 concentrations. This carbon must have been stored away from the atmosphere for thousands of years, yet the water mass structure accommodating such increased carbon storage continues to be debated. Here we present new sediment derived bottom water neodymium isotope data that allow fingerprinting of water masses and their mixtures and provide a more complete picture of the Atlantic overturning circulation geometry during the Last Glacial Maximums. These results suggest that the vertical and meridional structure of the Atlantic deep water mass distribution only experienced minor changes since the last ice age. In particular, we find no compelling evidence supporting glacial southern sourced water substantially expanding to shallower depths and farther into the northern hemisphere than today, which has been inferred from stable carbon isotope reconstructions. We argue that depleted δ13C values observed in the deep Northwest Atlantic do not necessarily indicate the presence of southern sourced water. Instead, these values may represent a northern sourced water mass with lower than modern preformed δ13C values that were further modified downstream by increased sequestration of remineralized carbon, facilitated by a more sluggish glacial deep circulation. If proven to be correct, the glacial water mass structure inferred from Nd isotopes has profound implications on our understanding of the deep ocean carbon storage during the Last Glacial Maximum.

How to cite: Pöppelmeier, F., Blaser, P., Gutjahr, M., Jaccard, S., Frank, M., Max, L., and Lippold, J.: Northern Sourced Water dominated the Atlantic Ocean during the Last Glacial Maximum, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1353, https://doi.org/10.5194/egusphere-egu2020-1353, 2019

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