1. Department of Geological Sciences and Bolin Centre for Climate Research; Stockholm University; SE-10691 Stockholm Sweden
2. Department of Physical Geography and Bolin Centre for Climate Research; Stockholm University; SE-10691 Stockholm Sweden
3. Department of Geology; University Centre in Svalbard (UNIS); PO Box 156 NO-9171 Longyearbyen Norway
4. Centre for Ice and Climate; Niels Bohr Institute; University of Copenhagen; 2100 Copenhagen Denmark
5. Department of Geography; Royal Holloway University of London; London TW20 0EX UK