Basal temperature evolution of North American ice sheets and implications for the 100‐kyr cycle
Bibliographic record
Abstract
We simulate three‐dimensional ice temperature fields to examine spatial‐temporal history of the subglacial thermal environment during the last glacial cycle. Model results suggest that 60–80% of the Laurentide Ice Sheet was cold‐based (frozen to the bed) at the LGM, and therefore unable to undergo large‐scale basal flow. The fraction of warm‐based ice increases significantly through the ensuing deglaciation, with only 10–20% of the Laurentide Ice Sheet frozen to the bed by 8 kyr BP. This basal thermal evolution, a function of both climatic and ice sheet history, could enable a dynamical switch to widespread basal flow through the deglacial period. Because basal flow has the capacity to evacuate large amounts of ice from the interior of continental ice sheets, creating thin and climatically‐vulnerable ice masses, this switch in flow regime may have played a significant role in glacial terminations and the 100‐kyr glacial cycle.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".