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Abstract The variability of Arctic sea ice extent (SIE) on interannual and multidecadal time scales is examined in 29 models with historical forcing participating in phase 6 of the Coupled Model Intercomparison Project (CMIP6) and in twentieth-century sea ice reconstructions. Results show that during the historical period with low external forcing (1850–1919), CMIP6 models display relatively good agreement in their representation of interannual sea ice variability (IVSIE) but exhibit pronounced intermodel spread in multidecadal sea ice variability (MVSIE), which is overestimated with respect to sea ice reconstructions and is dominated by model uncertainty in sea ice simulation in the subpolar North Atlantic. We find that this is associated with differences in models’ sensitivity to Northern Hemispheric sea surface temperatures (SSTs). Additionally, we show that while CMIP6 models are generally capable of simulating multidecadal changes in Arctic sea ice from the mid-twentieth century to present day, they tend to underestimate the observed sea ice decline during the early twentieth-century warming (ETCW; 1915–45). These results suggest the need for an improved characterization of the sea ice response to multidecadal climate variability in order to address the sources of model bias and reduce the uncertainty in future projections arising from intermodel spread. Significance StatementThe credibility of Arctic sea ice predictions depends on whether climate models are capable of reproducing changes in the past climate, including patterns of sea ice variability which can mask or amplify the response to global warming. This study aims to better understand how latest-generation global climate models simulate interannual and multidecadal variability of Arctic sea ice relative to available observations. We find that models differ in their representation of multidecadal sea ice variability, which is overall larger than in observations. Additionally, models underestimate the sea ice decline during the period of observed warming between 1915 and 1945. Our results suggest that, to achieve better predictions of Arctic sea ice, the realism of low-frequency sea ice variability in models should be improved.
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This content will become publicly available on June 16, 2027
Historical Volcanic Eruptions Mitigated the Expected Rapid Arctic Sea Ice Decline Prior to 2000
Abstract Arctic sea ice has declined at sharply contrasting rates over the past four decades—modest before 2000 and rapid thereafter. Using observational and model evidence, we show that large tropical volcanic eruptions can trigger decade‐long Arctic sea ice recoveries, and that without the 1982 El Chichón and 1991 Pinatubo eruptions, Arctic sea ice would have declined approximately 1.5 times faster before 2000. We further show a model's sensitivity to volcanic aerosol forcing scales with its sensitivity to GHG forcing across CMIP6 models, offering a new strategy to identify models with realistic climate response to radiative forcing. Following this, a selected subgroup of models that accurately simulate long‐term warming trend and decade‐long post‐Pinatubo recovery project ice‐free Arctic summer up to 20 years earlier than the full ensemble. These findings underscore the critical, yet underappreciated, importance of evaluating climate models against anthropogenic and volcanic forcing when projecting the future of Arctic sea ice.
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- Award ID(s):
- 2246601
- PAR ID:
- 10692286
- Publisher / Repository:
- AGU
- Date Published:
- Journal Name:
- Geophysical Research Letters
- Volume:
- 53
- Issue:
- 11
- ISSN:
- 0094-8276
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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