Publication Abstracts
Sime et al. 2026
Sime, L.C., R. Diamond, C. Stepanek, C. Brierley, D. Schroeder, M. Kageyama, M. Pollock, I. Malmierca-Vallet, E. Blockley, A. West, D. Feltham, J. Ridley, P. Braconnot, C.J.R. Williams, X. Shi, B.L. Otto-Bliesner, S.I. Macarewich, S. Ramos Buarque, Q. Zhang, , W. Zheng, D. Jiang, P. Morozova, C. Guo, Z. Zhang, N. Yeung, L. Menviel, S. Narayanasetti, O. Reeves, and A. Zhao, 2026: A sea ice free Arctic: CMPIS7 Assessment Fast Track abrupt-127k experimental protocol and motivation. Geosci. Model Dev., 19, no. 13, 5881-5905, doi:10.5194/gmd-19-5881-2026.
Given that the Arctic could be ice-free in summer within the next ten to 20 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/m2 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 budget including ice melt, growth, and transport. We show that a large Arctic ice response will manifest within the first 30 years of the simulation, thus a single 100-year long run is sufficient for these objectives. Modelling groups are requested to follow standard CMIP output protocol for analysis, including the use of standard "fixed-length" output. Given abrupt-127k is similar in setup to abrupt-2×CO2 and abrupt-4×CO2 CMIP7 experiments, combined analysis of these abrupt-experiments will facilitate understanding of the impacts of instantaneous radiative forcing in the Arctic.
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BibTeX Citation
@article{si00600i,
author={Sime, L. C. and Diamond, R. and Stepanek, C. and Brierley, C. and Schroeder, D. and Kageyama, M. and Pollock, M. and Malmierca-Vallet, I. and Blockley, E. and West, A. and Feltham, D. and Ridley, J. and Braconnot, P. and Williams, C. J. R. and Shi, X. and Otto-Bliesner, B. L. and Macarewich, S. I. and Ramos Buarque, S. and Zhang, Q. and LeGrande, A. and Zheng, W. and Jiang, D. and Morozova, P. and Guo, C. and Zhang, Z. and Yeung, N. and Menviel, L. and Narayanasetti, S. and Reeves, O. and Zhao, A.},
title={A sea ice free Arctic: CMPIS7 Assessment Fast Track abrupt-127k experimental protocol and motivation},
year={2026},
journal={Geoscientific Model Development},
volume={19},
number={13},
pages={5881--5905},
doi={10.5194/gmd-19-5881-2026},
}
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RIS Citation
TY - JOUR ID - si00600i AU - Sime, L. C. AU - Diamond, R. AU - Stepanek, C. AU - Brierley, C. AU - Schroeder, D. AU - Kageyama, M. AU - Pollock, M. AU - Malmierca-Vallet, I. AU - Blockley, E. AU - West, A. AU - Feltham, D. AU - Ridley, J. AU - Braconnot, P. AU - Williams, C. J. R. AU - Shi, X. AU - Otto-Bliesner, B. L. AU - Macarewich, S. I. AU - Ramos Buarque, S. AU - Zhang, Q. AU - LeGrande, A. AU - Zheng, W. AU - Jiang, D. AU - Morozova, P. AU - Guo, C. AU - Zhang, Z. AU - Yeung, N. AU - Menviel, L. AU - Narayanasetti, S. AU - Reeves, O. AU - Zhao, A. PY - 2026 TI - A sea ice free Arctic: CMPIS7 Assessment Fast Track abrupt-127k experimental protocol and motivation JA - Geosci. Model Dev. JO - Geoscientific Model Development VL - 19 IS - 13 SP - 5881 EP - 5905 DO - 10.5194/gmd-19-5881-2026 ER -
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