A local meteoric water line for interior Alaska constrains paleoclimate from 40 000 year old relict permafrost
Bibliographic record
Abstract
Abstract Anthropogenic climate warming is degrading permafrost across interior Alaska. Information from past warming events provides long-term perspectives for future trajectories; however, late Quaternary seasonal temperatures are poorly constrained. We have established a stable water isotope meteoric water line for interior Alaska and measured stable water isotope values from 126 permafrost cores representing different ice types deposited over the past ∼40 ka (thousand years before 1950 CE). Samples represent two late Quaternary warm periods: marine isotope stage three (MIS3; 57–29 ka) and the Holocene (11.7 ka-present). Older samples provide insight into local climatic conditions slightly before the first archeological evidence for Paleolithic hunter-gatherers in the region. From permafrost ice we calculate that summer temperatures warmed by ∼10 °C between late MIS3 and today, with six degrees of warming between 40–30 ka and 3 ka and an additional 4 °C of warming since 3 ka. Half this recent 4 °C warming has occurred over the past 70 years.
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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 | 0.000 |
| Science and technology studies | 0.000 | 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".