EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Tree-ring radiocarbon reveals reduced solar activity during Younger Dryas cooling

Adam Sookdeo1,2, Bernd Kromer3, Florian Adolphi4,5, Jürg Beer6, Nicolas Brehm2, Ulf Büntgen7,8,9, Marcus Christl2, Timothy Eglinton10, Micheal Friedrich3,11, Giulia Guidobaldi2, Gerd Helle12, Raimund Muscheler5, Daniel Nievergelt8, Maren Pauly13, Frederick Reinig8,14, Willy Tegel15, Kerstin Treydte8, Chris Turney2,16, Hans-Arno Synal2, and Lukas Wacker2
Adam Sookdeo et al.
  • 1UNSW, Analytical Chemistry, Chronos 14Carbon-Cycle Facility, Sydney, Australia (
  • 2ETH-Zürich, Laboratory of Ion Beam Physics, Zürich, Switzerland
  • 3Heidelberg University, Institute of Environmental Physics, Heidelberg, Germany
  • 4University of Bern, Climate and Environmental Physics & Oeschger Center for Climate Change Research, Bern, Switzerland
  • 5Lund University, Department of Geology-Quaternary Sciences, Lund, Sweden
  • 6Swiss Federal Institute of Aquatic Science and Technology EAWAG, Zürich, Switzerland
  • 7Swiss Federal Research Institute WSL, Birmensdorf, Switzerland
  • 8University of Cambridge, Department of Geography, Cambridge, UK
  • 9University Brno, Global Change Research Institute CAS and Masaryk, Brno, Czech Republic
  • 10ETH-Zurich, Carbon Cycle Biogeoscience, Zürich, Switzerland
  • 11Hohenheim University, Institute of Botany, Stuttgart, Germany
  • 12GFZ German Research Centre for Geosciences, Potsdam, Germany
  • 13Bath Spa Univerisity, School of Science, Bath, UK
  • 14University Mainz, Department of Geography, Johannes Gutenberg, Germany
  • 15Albert-Ludwigs University of Freiburg, Freiburg, Germany
  • 16Palaeontology, Geobiology and Earth Archives Research Centre (PANGEA), University of New South Wales, Sydney, Australia

The Younger Dryas stadial (YD) was a return to glacial-like conditions in the North Atlantic region that interrupted deglacial warming around 12900 cal BP (before 1950 AD). Terrestrial and marine records suggest this event was initiated by the interruption of deep-water formation arising from North American freshwater runoff, but the causes of the millennia-long duration remain unclear. To investigate the solar activity, a possible YD driver, we exploit the cosmic production signals of tree-ring radiocarbon (14C) and ice-core beryllium-10 (10Be). Here we present the highest temporally resolved dataset of 14C measurements (n = 1558) derived from European tree rings that have been accurately extended back to 14226 cal BP (±8, 2-σ), allowing precise alignment of ice-core records across this period. We identify a substantial increase in 14C and 10Be production starting at 12780 cal BP is comparable in magnitude to the historic Little Ice Age, being a clear sign of grand solar minima. We hypothesize the timing of the grand solar minima provides a significant amplifying factor leading to the harsh sustained glacial-like conditions seen in the YD.

How to cite: Sookdeo, A., Kromer, B., Adolphi, F., Beer, J., Brehm, N., Büntgen, U., Christl, M., Eglinton, T., Friedrich, M., Guidobaldi, G., Helle, G., Muscheler, R., Nievergelt, D., Pauly, M., Reinig, F., Tegel, W., Treydte, K., Turney, C., Synal, H.-A., and Wacker, L.: Tree-ring radiocarbon reveals reduced solar activity during Younger Dryas cooling, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11654,, 2020