1. Centre for Ice and Climate, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100, Copenhagen OE, Denmark
2. Department of Geology, Lunds University, Sölvegatan 12, SE-22362, Lund, Sweden
3. Laboratoire des Science du Climat et de l'Environnement CEA-CNRS-UVSQ-IPSL, Saclay, France
4. Institute for Marine and Atmospheric Research Utrecht (IMAU), Utrecht University, Utrecht, The Netherlands