On the factors behind large Labrador Sea tides during the last glacial cycle and the potential implications for Heinrich events
Bibliographic record
Abstract
Labrador Sea (LS) tidal elevations over the last glacial cycle are investigated in a near‐global numerical model that accurately captures the present‐day tides. From ∼65 ka to ∼7 ka, the modeled elevations at the debouchement point of the Hudson Strait ice stream in the LS are exceptionally large, comparable to the largest elevations seen anywhere in the present‐day ocean. New numerical simulations performed for this article demonstrate that both local changes in basin geometry (e.g., ice cover over Hudson Bay) and changes outside of the LS led to enhanced LS paleotides. New simulations run at higher horizontal resolution and a considered examination of uncertainties, including uncertainties in the adopted sea level models, strengthen confidence in the robustness of the large LS paleotides. The tide model is run with both spatially uniform sea level drops (taken from curves of eustatic and Red Sea sea levels versus time) and spatially variable sea level maps (taken from two different gravitationally self‐consistent viscoelastic solid earth/sea level models, which both account for ice sheet geometry). The tides are larger when the spatially variable sea level models are used. Observations in present‐day Antarctica indicate that the mechanical action of tides significantly impacts the dynamics of both continental ice streams and their associated floating ice shelves. It is postulated here that large LS paleotides played a key role in the formation of Heinrich event icebergs, that is, massive discharges of ice from the LS into the glacial North Atlantic ocean. The paleotide calculations described here provide a potential explanation for why the LS region, more than any other, dominated the production of Heinrich event icebergs. Most previous hypotheses of a tidal role in climate variability and ice sheet dynamics focus on tidal mixing. In contrast, here the role of tidal mechanical forcing of ice sheets is emphasized.
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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 | 0.001 | 0.003 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".