1. Rubenstein School of the Environment and Natural Resources, University of Vermont, Burlington, VT 05405, USA.
2. Gund Institute for Environment, University of Vermont, Burlington, VT 05405, USA.
3. Department of Geosciences, Utah State University, Logan, UT 84322, USA.
4. University of Texas Institute for Geophysics, Jackson School of Geosciences, University of Texas at Austin, Austin, TX 78754, USA.
5. Geological Survey of Denmark and Greenland, 1350 Copenhagen, Denmark.
6. Department of Earth Sciences, University of Connecticut, Storrs, CT 06269, USA.
7. Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10964, USA.
8. Laboratoire de Glaciologie, DGES-IGEOS, Université Libre de Bruxelles, 1050 Brussels, Belgium.
9. Centre de Recherches Pétrographiques et Géochimiques, CNRS, Université de Lorraine, 54500 Nancy, France.
10. Centre for Ice and Climate, PICE, Niels Bohr Institute, University of Copenhagen, 2200 Copenhagen, Denmark.
11. Department of Physics and Astronomy, Purdue University, West Lafayette, IN 47907, USA.
12. Department of Earth, Atmospheric, and Planetary Sciences, Purdue University, West Lafayette, IN 47907, USA.
13. Centre for Earth Observation Science, University of Manitoba, Winnipeg, MB R3T 2N2, Canada.
14. Department of Geosciences, Williams College, Williamstown, MA 01267, USA.
15. Center for Accelerator Mass Spectrometry, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA.
16. Department of Geography and Geosciences, University of Vermont, Burlington, VT 05405, USA.
17. NASA Goddard Institute for Space Studies, New York, NY 10025, USA.
18. Department of Earth and Space Sciences, University of Washington, Seattle, WA 98195, USA.
19. Department of Geology, University at Buffalo, Buffalo, NY 14260, USA.