The response of North American ice sheets to the Younger Dryas (12.9 ka to 11.7 ka) climate event
Bibliographic record
Abstract
The response of continental ice sheets to late glacial climate fluctuations (Bølling warming, Younger Dryas cooling) offers key insight into the interconnectedness between ice sheets and climate. The Younger Dryas was an abrupt climate cooling event that occurred between 12.9 ka and 11.7 ka, as the Northern Hemisphere was undergoing progressive deglaciation from the last glacial maximum (~25 ka). Ice sheets in Northern Europe (Fennoscandian Ice Sheet) underwent a significant re-advance at that time. However, the reaction of North American ice sheets (Laurentide, Cordilleran, Innuitian; which comprise the largest ice mass in the Northern Hemisphere at the time) to Younger Dryas cooling is not well understood. Some localized studies have shown evidence of ice re-advance or stagnation corresponding to the Younger Dryas; however, no large-scale, unifying study of the impact of Younger Dryas cooling on North American ice sheets has been attempted. Here, we present preliminary maps showing the response of North American ice sheets to the Younger Dryas climate event in key regions. To delineate changes in the ice margin, we integrate a geochronological dataset consisting of calibrated radiocarbon ages and cosmogenic nuclide ages, with mapping of glacial features (ie. moraines) and an extensive literature review. Results suggest a highly variable response of North American ice sheets to Younger Dryas cooling, notably a re-advance of remnant ice lobes in eastern Canada, and stagnation of the ice margin at more western sites.
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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 | 0.003 | 0.004 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| 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".