[1] Univ Bern, Phys Inst, Climate & Environm Phys, CH-3012 Bern, Switzerland
[2] Univ Bern, Oeschger Ctr Climate Change Res, CH-3012 Bern, Switzerland
[3] Univ Bern, Inst Geol Sci, CH-3012 Bern, Switzerland
[4] Univ Reading, Sch Archaeol Geog & Environm Sci, Dept Archaeol, Reading, Berks, England
[5] Univ Reading, Sch Archaeol Geog & Environm Sci, Ctr Past Climate Change, Reading, Berks, England
[6] Univ Minnesota, Dept Earth Sci, Minneapolis, MN 55455 USA
[7] Xian Jiatong Univ, Inst Global Environm Change, Xian 710049, Shaanxi, Peoples R China
[8] Int Fdn High Altitude Res Stn Jungfraujoch & Gorn, CH-3012 Bern, Switzerland