The Laki eruption and observed dendroclimatic effects of volcanism
Bibliographic record
Abstract
The year of the Laki eruption, 1783, is the most visibly obvious anomaly in the northwestern Alaska tree-ring record for over 400 years or more. Thicker-walled, latewood cells formed late in the growing season are virtually absent. Quantitatively the latewood density is over 4 standard deviations below the mean latewood density of white spruce (Picea glauca) trees from northwest Alaska; indication of extreme cold during the summer season in this region. The tree-ring response to the event weakens toward the east, indicating that extreme cold did not extend much beyond the Mackenzie River in western Canada or very far south of the Alaska Range in central Alaska. To understand the tree-ring effects due to the Laki eruption, it is helpful to also consider three other similar events in 1641, 1816-17, and 1836. In each case there is evidence of extreme cold causing very low density latewood in the rings of white spruce near the latitudinal treeline. The effects in the tree-ring record are spatially variable. Evidence of extreme cold typically extends for about 60°-70° of longitude; 1641 in north western-and-central Canada, 1783 in Alaska, 1816-17 in eastern Canada, and 1836 in north-central Canada. One interpretation of this spatial and temporal pattern is that in addition to general cooling, the thermal effects of volcanic events can lead to outbreaks of extremely cold polar air on a regional basis. This interpretation is compatible with air mass trajectories driven by Rossby wave circulation. Such extreme regional cooling can have great impact on human conditions.
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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 | 0.000 | 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".