1. Department of Geochemistry, Geological Survey of Denmark and Greenland (GEUS); Øster Voldgade 10, DK-1350, Copenhagen Denmark
2. Center for Permafrost (CENPERM); University of Copenhagen; Øster Voldgade 10, DK-1350, Copenhagen Denmark
3. Department of Ecology; Faculty of Science, Charles University; Viničná 7, 128 43, Prague Czech Republic
4. Bristol Glaciology Centre, School of Geographical Sciences; University of Bristol; University Road, BS8 1SS, Bristol, UK
5. Department of Environmental Science; Aarhus University; Frederiksborgvej 399, DK-4000, Roskilde Denmark