Astronomically-induced abrupt cooling at the end of the last interglacial
Bibliographic record
Abstract
Paleoclimate records show that the end of the last interglacial (MIS-5e) was marked by abrupt cooling events and other abrupt climate changes such as abrupt weakening of the Asia summer monsoon. Strong abrupt cooling occurring when the climate was still in a warm condition is puzzling and its cause remains uncertain. Our LOVECLIM1.3 transient simulations covering the period 133ka-111ka show that there exists a threshold in the astronomically-induced slow variation of insolation below which abrupt changes at the end of MIS-5e occur. When the summer insolation in the Northern Hemisphere (NH) high latitudes decreases to a critical value, it triggers a strong, abrupt weakening of the Atlantic meridional overturning circulation (AMOC) and a strong cooling in the NH followed by high-amplitude variations. The mechanism involves sea ice feedbacks in the Northern Nordic Sea and the Labrador Sea. Similar abrupt oscillations happen in the simulated temperature, precipitation and vegetation from low to high latitudes as well as in the NH snow and sea ice. Taking into account age uncertainty in the proxy records, the timing of the abrupt cooling in our model (119.8ka) corresponds well with the timing of abrupt changes observed in many marine and terrestrial records, such as the Greenland ice core records, various marine records in the North Atlantic, the Chinese speleothem and loess records and some lacustrine records in low and high latitudes. Our simulations for the other interglacials of the past 800ka show that the insolation threshold occurred also at the end of other interglacials, suggesting its fundamental role in terminating the warm condition of the interglacials.
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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 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| 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".