The weakening AMOC under extreme climate change
Bibliographic record
Abstract
We examine changes in the Atlantic Meridional Overturning Circulation (AMOC) in the quadrupled CO2 experiments conducted under the sixth Coupled Model Intercomparison Project (CMIP6). While the forcing is extreme, the abrupt nature of the transition facilitates diagnosing how the system responds. The increase in CO2 triggers Arctic amplification of warming, causing widespread melting of sea ice. The resulting freshwater enters the ocean, first from the Labrador Sea and then from the Nordic Seas, and proceeds southward along the eastern coast of North America. The freshwater enters the subpolar gyre to the north of the separated Gulf Stream, decreasing the density contrast across the current. The current weakens in response, reducing the inflow to the deepwater production regions. The AMOC cell weakens in response, first in the region of the Gulf Stream and then widening to higher and lower latitudes. The response contrasts with the present perception that freshwater “caps the convection regions”, stifling deep water production. Changes in surface temperature have a weaker effect and there are no consistent changes in local or remote wind forcing among the models. The results thereby indicate that an increase in freshwater discharge, primarily from the Labrador Sea, is a precursor to AMOC weakening.
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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 | 0.000 | 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".