Sea-ice-free arctic during the last interglacial supports fast future loss

ABSTRACT The Last Interglacial (LIG), a warmer period 130,000–116,000 years before present, is a potential analogue for future climate change. Stronger LIG summertime insolation at high

northern latitudes drove Arctic land summer temperatures 4–5 °C higher than in the pre-industrial era. Climate model simulations have previously failed to capture these elevated

temperatures, possibly because they were unable to correctly capture LIG sea-ice changes. Here, we show that the latest version of the fully coupled UK Hadley Center climate model (HadGEM3)

simulates a more accurate Arctic LIG climate, including elevated temperatures. Improved model physics, including a sophisticated sea-ice melt-pond scheme, result in a complete simulated loss

of Arctic sea ice in summer during the LIG, which has yet to be simulated in past generations of models. This ice-free Arctic yields a compelling solution to the long-standing puzzle of

what drove LIG Arctic warmth and supports a fast retreat of future Arctic summer sea ice. Access through your institution Buy or subscribe This is a preview of subscription content, access

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institutional subscriptions * Read our FAQs * Contact customer support SIMILAR CONTENT BEING VIEWED BY OTHERS LONG- AND SHORT-TERM VARIABILITY OF ARCTIC SEA-ICE COVER DURING THE LAST

INTERGLACIAL AND MARINE ISOTOPE STAGE 11C Article Open access 08 April 2025 EAST ANTARCTIC WARMING FORCED BY ICE LOSS DURING THE LAST INTERGLACIAL Article Open access 03 February 2024

ACCELERATION OF WESTERN ARCTIC SEA ICE LOSS LINKED TO THE PACIFIC NORTH AMERICAN PATTERN Article Open access 09 March 2021 DATA AVAILABILITY The CMIP3-6 model data used in this study to

compute ECS and ice-free years are available from the Earth System Grid Federation (https://esgf-node.llnl.gov/). The HadCM3 and HadGEM3 model outputs used to support the findings of this

study are available from http://gws-access.ceda.ac.uk/public/pmip4/vittoria/CMIP6LIG_HadGEM3_CMIP3_HadCM3/. The HadGEM3 model outputs prepared for CMIP6 can be found at

https://doi.org/10.22033/ESGF/CMIP6.419 (ref. 54). The authors declare that all other data are available in the paper and its Supplementary Information. CODE AVAILABILITY The source code of

the HadCM3 model and the HadGEM3 model’s atmospheric component (Unified Model) is available under licence. To apply for a licence, go to

http://www.metoffice.gov.uk/research/modelling-systems/unified-model. JULES is available under licence free of charge; see https://jules-lsm.github.io/. The NEMO model code is available from

http://www.nemo-ocean.eu. The model code for CICE can be downloaded from https://code.metoffice.gov.uk/trac/cice/browser. CHANGE HISTORY * _ 30 AUGUST 2023 A Correction to this paper has

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Model Output Prepared for CMIP6_ (Earth System Grid Federation, 2018); https://doi.org/10.22033/ESGF/CMIP6.419 Download references ACKNOWLEDGEMENTS M.-V.G. acknowledges support from NERC

research grant no. NE/P013279/1. L.C.S. acknowledges support through grant nos NE/P013279/1, NE/P009271/1 and EU-TiPES. The project has received funding from the European Union’s Horizon

2020 research and innovation programme under grant agreement no. 820970. D.S. acknowledges support from the NERC-UKESM program. I.M.-V. acknowledges support from a NERC PhD studentship and

EU-TiPES. E.W. is supported by a Royal Society Research Professorship. E.J.S. and C.B. acknowledge support by the US National Science Foundation through NSFGEO-NERC award no. 1602435. J.S

acknowledges support from the Canada 150 Research Chairs program, C150 grant no. 50296. This work used the ARCHER UK National Supercomputing Service (http://www.archer.ac.uk) and the JASMIN

data analysis platform (http://jasmin.ac.uk/). In addition, we thank S. Belt for helpful discussions on IP25 LIG sea-ice interpretations, B. Otto-Bliesner for providing the published CMIP5

LIG summer temperature observations and NCAS for supporting the LIG model simulations. AUTHOR INFORMATION Author notes * These authors contributed equally: Maria-Vittoria Guarino, Louise C.

Sime. AUTHORS AND AFFILIATIONS * British Antarctic Survey, Cambridge, UK Maria-Vittoria Guarino, Louise C. Sime & Irene Malmierca-Vallet * Department of Meteorology, University of

Reading, Reading, UK David Schröeder & Danny Feltham * Centre of Earth Observation Science, University of Manitoba, Winnipeg, Manitoba, Canada Erica Rosenblum & Julienne Stroeve *

The Met Office, Exeter, UK Mark Ringer, Jeff Ridley & Alistair Sellar * Department of Atmospheric Sciences, University of Washington, Seattle, WA, USA Cecilia Bitz & Eric J. Steig *

Department of Earth and Space Sciences, University of Washington, Seattle, WA, USA Eric J. Steig * Department of Earth Sciences, University of Cambridge, Cambridge, UK Eric Wolff Authors *

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Google Scholar CONTRIBUTIONS L.C.S. oversaw the direction and formulation of the research. M.-V.G. carried out the HadGEM3 simulations and analysed all simulation results. D.S. helped guide

the interpretation of the simulation results. I.M.-V. ran the HadCM3 simulations. E.R. helped with the CMIP3-6 projected sea-ice-free analysis. M.R. computed the CMIP6 ECS data. J.R.

assisted with the HadGEM3 data post-processing. All authors read the manuscript and provided comments. L.C.S. and M.-V.G. wrote the manuscript. CORRESPONDING AUTHORS Correspondence to

Maria-Vittoria Guarino or Louise C. Sime. ETHICS DECLARATIONS COMPETING INTERESTS The authors declare no competing interests. ADDITIONAL INFORMATION PUBLISHER’S NOTE Springer Nature remains

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permissions ABOUT THIS ARTICLE CITE THIS ARTICLE Guarino, MV., Sime, L.C., Schröeder, D. _et al._ Sea-ice-free Arctic during the Last Interglacial supports fast future loss. _Nat. Clim.

Chang._ 10, 928–932 (2020). https://doi.org/10.1038/s41558-020-0865-2 Download citation * Received: 06 December 2019 * Accepted: 07 July 2020 * Published: 10 August 2020 * Issue Date:

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