The Toba Eruption 74,000 Years ago Strengthened the Indian Winter Monsoon‐Evidence From Coccolithophores
Bibliographic record
Abstract
Abstract The global impact of the Youngest Toba Tuff (YTT) supereruption is still heavily debated, ranging from having little effects on climate to significantly affecting modern human evolution. Climate models and proxy records show that the eruption may have caused cooling of the Asian landmass, thus impacting regional climate such as the Indian monsoon system. However, the immediate effect of the eruption on the Indian monsoon has not been indisputably demonstrated in any proxy record. Here, we present a paleo‐primary productivity (PP) record in core SO130‐289KL from the northeastern Arabian Sea based on the coccolithophore species Florisphaera profunda transfer function. Florisphaera profunda decreased from ∼30% before the YTT eruption to ∼8% right after the YTT eruption, which translates to an increase in PP by ∼65% from a long‐term average of ∼200 gC/m2/yr for about 8–19 years after the eruption. The duration was estimated using a new error‐weighted mean age of the YTT eruption (73.9 ± 0.1 ka, 2σ uncertainties) based on recent age estimates from ice cores, radiometric dating, and speleothem records. The elevated PP is most likely linked to the deepening of the surface ocean mixed layer driven by strengthened northeasterly Indian winter monsoon winds. This hypothesis is supported by stable oxygen isotope records from speleothem and ice cores, which show indications of a strengthening of the Indian winter monsoon during times of increased PP. Our results support previous modeling studies and provide unequivocal evidence from a marine record for an Indian monsoon response to the supereruption.
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| 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) | 0.002 | 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".