Bibliographic record
Abstract
concern about the magnitude and rate of future climate change looms, it becomes increasingly important to understand the mechanisms underlying past abrupt climate change events. A cold event that occurred 8200 years ago, although much less Enhanced online at extreme than some www.sciencemag.org/cgi/ events during the Ice content/full/301/5635/922 Ages, is probably most amenable to detailed examination because it is the most recent such event. According to the ice-core record from Greenland, the abrupt cooling 8200 years ago was the largest climate excursion of the past 10,000 years (1, 2): The mean temperature dropped by about 5°C for about 200 years (see the figure, A), snow accumulation decreased sharply, precipitation of chemical impurities increased, and forest fires became more frequent. The event, which affected much of the Northern Hemisphere (3–5), appears to have been triggered by the sudden release of fresh water from a huge, glacierdammed lake that had formed during the deglaciation of North America (6). Changes in the volume and extent of the ice sheets that once covered much of North America directly influenced the freshwater balance of the North Atlantic and are implicated in many abrupt climate events of the past 100,000 years (7, 8). During the last Ice Age, when a kilometers-thick ice sheet covered most of Canada and parts of the northern United States, armadas of icebergs were episodically launched into the North Atlantic. The melting of this freshwater ice and the associated freshening of ocean surface waters are believed to have changed the strength of the oceanic thermohaline circulation (9), thereby causing abrupt climate changes.
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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 | 0.003 | 0.007 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.003 | 0.009 |
| Scholarly communication | 0.004 | 0.006 |
| Open science | 0.001 | 0.008 |
| Research integrity | 0.003 | 0.004 |
| Insufficient payload (model declined to judge) | 0.022 | 0.002 |
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".