Ocean circulation shifts and sea-ice decline in the North Atlantic-Arctic sector during the Last Interglacial
Bibliographic record
Abstract
The Last Interglacial (127,000–116,000 years before present) is characterized by higher Arctic surface temperatures relative to the pre-industrial era. During this period, the Arctic experienced significant summer sea-ice reduction, with some studies suggesting the possibility of an ice-free Arctic Ocean at the end of summers. These changes in sea-ice cover were primarily driven by increased summer solar insolation caused by orbital configuration at that time, but they may also have been influenced by shifts in oceanic conditions. Paleoceanographic studies generally assume modern-like circulation patterns when interpreting proxy data. However, the stability of oceanic circulation under Last Interglacial forcing and its potential impact on sea-ice loss remain poorly understood.Using simulations from the last Coupled Model Intercomparison Project (CMIP6/PMIP4), we analysed differences in surface ocean circulation between the Last Interglacial and pre-industrial periods, and their effect on annual sea-ice variations. Our results indicate an anomalous cyclonic circulation over Greenland and the surrounding seas, which leads to intensified Baffin and Labrador Currents west of Greenland and a weakened East Greenland Current. These changes affect sea-ice drift and water transports outside the Arctic Basin. Furthermore, models generally simulate a strengthening of the North Atlantic subpolar gyre during the Last Interglacial, associated with increased Atlantic inflows south of Greenland and towards the Nordic Seas. Despite these changes, we found no consistent evidence of "Atlantification" of the Arctic during the Last Interglacial. This contrasts with future CO2 emission scenarios, where similar reductions in annual sea-ice volume are accompanied by Atlantification.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".