1. British Antarctic Survey Cambridge UK
2. Department of Chemistry University of Cambridge Cambridge UK
3. Antarctic Climate and Ecosystems University of Tasmania Hobart Tasmania Australia
4. Physics of Ice, Climate and Earth, Niels Bohr Institute University of Copenhagen Copenhagen Denmark
5. Division of Geological and Planetary Sciences California Institute of Technology Pasadena CA USA
6. Climate Change Institute University of Maine Orono ME USA
7. School of Earth and Climate Sciences University of Maine Orono ME USA
8. Now at: Research School of Earth Sciences Australian National University Canberra ACT Australia
9. Department of Earth Sciences University of Cambridge Cambridge UK
10. Department of Environmental Sciences University of Basel Basel Switzerland