Andrei V Kurbatov¹, Geoffrey Hargreaves², Roisin Rumsey³, Sara Akiba⁴, Daniel Breton⁵, Edward J Brook⁶, Christo Buizert⁷, John M Fegyveresi⁸, Tyler J Fudge⁹, Curtis LaBombard², Richard Nunn² and Mikhail N Zhizhin¹⁰, (1)University of Maine, Orono, ME, United States, (2)U.S. National Science Foundation Ice Core Facility, Lakewood, United States, (3)University of Maine, Climate Change Institute, Orono, United States, (4)Princeton University, Department of Geosciences, Princeton, NJ, United States, (5)ERDC-CRREL, Hanover, United States, (6)Oregon State University, Corvallis, United States, (7)Oregon State University, Corvallis, OR, United States, (8)The Pennsylvania State University, University Park, United States, (9)University of Washington, Earth and Space Sciences, Seattle, United States, (10)Colorado School of Mines, Payne Institute for Public Policy, Golden, United States