Volcanic climate forcing preceding the inception of the Younger Dryas: Implications for tracing the Laacher See eruption
Bibliographic record
Abstract
Climatic warming from the last glacial maximum to the current interglacial period was punctuated by a ∼1300 years long cold period, commonly referred to as the Younger Dryas (YD). Several hypotheses have been proposed for the mechanism triggering the abrupt inception of the YD, including freshwater forcing, an extra-terrestrial impact, and aerosols from volcanic eruptions. Here, we use synchronised sulphate and sulphur records from both Greenland and Antarctic ice cores to reconstruct volcanic forcing between 13,200–12,800 a BPGICC05 (years before 1950 CE on the Greenland Ice Core Chronology 2005; GICC05). This continuous reconstruction of stratospheric sulphur injections highlights a ∼110-year cluster of four major bipolar volcanic signals alongside several smaller events just prior to the YD inception. The cumulative Northern Hemisphere aerosol burden and radiative forcing from this cluster exceeds the most volcanically active periods during the Common Era, which experienced notable multidecadal scale cooling commonly attributed to volcanic effects. The Laacher See eruption (LSE), recently redated to 13,006 ± 9 cal a BP, falls within our time window of study and has been proposed as a trigger for the YD but a direct volcanic imprint for the LSE in the Greenland ice cores has thus far proved elusive. Comparison of simulated sulphate deposition for mid- and high-sulphur LSE-type emission scenarios to the ice-core estimated sulphate deposition and interhemispheric asymmetry ratios allows several signals between 13,025 and 12,975 a BPGICC05 to be proposed as plausible candidates for the LSE. The magnitude and persistence of volcanic forcing directly preceding the YD inception highlights the need to consider stratospheric sulphur injections and their radiative forcing in future analyses and climate model experiments used to explore the mechanisms that triggered this or similar abrupt cooling events.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| 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".