The marine record of abrupt climate change at Bay of Islands, Newfoundland
Bibliographic record
Abstract
This study assesses vegetational response to abrupt climatic changes that occurred between ca. 12,000 and 8,000 yr BP using a palynological record from Bay of Islands (west coast of Newfoundland). Western Newfoundland is located near the boundary of two major ecozones: the boreal forest and the tundra. This transition zone is very sensitive to climate change. Core MD99-2225 was extracted from Humber Arm at a depth of 104m, roughly 12km from the Humber River. Samples were analysed every 10cm between 10 and 25 m down-core. Pollen analysis was used to track the evolution of vegetation, and the proportions of both tundra and more thermophilous hardwood taxa were used to determine changes in ecotone. The pollen record was also used to reconstruct air temperatures. The dinoflagellate cyst record was used to reconstruct sea surface parameters, such as temperature, salinity and sea ice. Results reflect large shifts in the composition of the vegetation and of dinoflagellate cysts assemblages in response to three cold climatic events. At the onset of the Younger Dryas, air temperatures dropped by 5°C from -15°C in February and 16 °C in August, August SST dropped by 10°C from roughly 15°C, and the duration of the sea ice cover increased to 10 months yr-1. Conditions remained harsh between ca. 10,800-10,300 yr BP, Vegetation was dominated by shrubs and grasses and dinoflagellate cyst assemblages are characterized by low species diversity and dominance by arctic species, such as Brigantedinium spp. Sea surface and air temperatures improved following after the Younger Dryas. At ca. 9,000 yr BP, sea surface conditions and air temperatures decreased in the bay as a response to the Preboreal Oscillation. Shrubs and grasses re-invaded the region and dinoflagellate cyst assemblages showed a decrease in diversity and dominance by arctic species such as Brigantedinium spp. The last event to be detected in this record, the 8.2 ka cold period, had a smaller impact in the region. Sea surface temperatures as well as air temperature decreased, but for a short time. The proportion of shrub pollen increased slightly and cold water species (Brigantedinium spp., I. minutum and P. dalei) dominated the dinoflagellate cyst assemblages.
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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 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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".