1. Climate and Environmental Physics; Physics Institute; University of Bern; Bern Switzerland
2. Oeschger Centre for Climate Change Research; University of Bern; Bern Switzerland
3. Now at Scripps Institution of Oceanography; University of California; San Diego, La Jolla California USA
4. Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung; Bremerhaven Germany
5. LGGE, CNRS; Université Grenoble Alpes; Grenoble France