A sea ice free Arctic: Assessment Fast Track abrupt-127k experimental protocol and motivation

作者：Louise C. Sime, Rachel Diamond, Christian Stepanek, C. M. Brierley, David Schröeder, Masa Kageyama, Irene Malmierca‐Vallet, Ed Blockley, Alex West, Danny Feltham, Jeff Ridley, Pascale Braconnot, Charles J. R. Williams, Xiaoxu Shi, Bette L. Otto‐Bliesner, Sophia I. Macarewich, Silvana Ramos Buarque, Qiong Zhang, Allegra N. LeGrande, Weipeng Zheng, Dabang Jiang, Polina Morozova, Chuncheng Guo, Zhongshi Zhang, Nicholas K. H. Yeung, Laurie Menviel, Sandeep Narayanasetti, Olivia Reeves, Matthew Pollock, Anni Zhao · 年份：2025 · DOI：10.5194/egusphere-2025-3531 · 被引用次数：1 · 研究领域：Arctic and Antarctic ice dynamics、Icing and De-icing Technologies

Abstract. Given that the Arctic could be ice-free in summer within the next ten to twenty years, accurately predicting low-ice states is of crucial importance. Paleo-evidence shows that the strong orbitally-induced high latitude insolation anomaly at 127,000 years ago (127 ky), of around +70 W m−2 in the Arctic during spring-summer, led to warm conditions and an Arctic that was occasionally or often ice-free during summer. Building on two Coupled Model Intercomparison Projects (CMIPs): the Sea-Ice Model Intercomparison Project and the Paleoclimate Modelling Intercomparison Project, we propose an Assessment Fast Track experiment, abrupt-127k, focusing on this seasonally ice-free, or near ice-free, Arctic at 127 ky. The abrupt-127k experiment is initialised from a piControl simulation and abruptly imposes observed values for the insolation distribution and greenhouse gas forcing at 127 ky. It provides a new opportunity to evaluate models used to compute climate projections, both against paleo-evidence and each other, during a known low Arctic sea ice state. As CMIP models are not usually tuned to paleo observations, abrupt-127k represents a true ‘out-of-sample’ test. The abrupt-127k experiment has four key scientific objectives, to: ascertain the simulated Arctic sea ice state, including the presence and characteristics of last-ice areas; evaluate the simulated climates using Arctic paleo-evidence; characterise the central Arctic surface energy budget; and analyse the ice budge...