Recent and early 20th century destabilization of the subpolar North Atlantic recorded in bivalves
Bibliographic record
Abstract
Climate change risks triggering abrupt weakening in two climatically important North Atlantic Ocean circulation elements, the subpolar gyre and the Atlantic Meridional Overturning Circulation (AMOC). Loss of AMOC stability has been inferred from slowing recovery of temperature and salinity fluctuations over time. However, observational datasets, constructed from records with sparse spatial and temporal coverage, may introduce substantial biases in stability indicators. Alternative records are therefore needed for reliable stability assessments. Here, using bivalve-derived environmental reconstructions, we show that the subpolar North Atlantic has experienced two destabilization episodes over the past ~150 years. The first preceded the rapid circulation changes associated with the 1920s North Atlantic regime shift, suggesting that a tipping point may have been crossed in the early 20th century. The second and stronger destabilization began around 1950 and continues to the present, supporting evidence of recent stability loss and suggesting that the region is moving toward a tipping point.
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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 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 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".