1. Laboratoire des Sciences du Climat et de l'Environnement; UMR CEA-CNRS-UVSQ/IPSL; Gif-sur-Yvette France
2. Centre for Ice and Climate, Niels Bohr Institute; University of Copenhagen; Copenhagen Denmark
3. Institute of Earth Sciences; University of Iceland; Reykjavik Iceland
4. Geophysical Institute; University of Bergen; Bergen Norway