Canadian Arctic Neogene Temperatures Reconstructed From Hydrogen Isotopes of Lignin‐Methoxy Groups From Sub‐Fossil Wood
Bibliographic record
Abstract
Abstract Proxy‐based reconstructions of Neogene warm climates are a valuable data source for helping to understand what a future, warmer world may look like. Such insights are especially critical in the Arctic where the fastest rates of warming are underway and likely to continue. In this study, hydrogen isotopes of lignin‐methoxy groups (δ 2 H LM ) from Miocene and Pliocene sub‐fossil wood samples ( N = 43) at six high‐latitude sites (73–80°N) in the Canadian Arctic Archipelago were used to estimate mean δ 2 H values of precipitation and temperature anomalies (ΔT) relative to present. The ΔT estimates ranged from +9.7 to +16.7°C depending on site and epoch and are corroborated by a suite of independent proxy data for most sites, and for one site (Prince Patrick Island) this study provides the first quantitative ΔT estimates. These are conservative estimates as they do not account for the more negative δ 2 H seawater values during the Neogene. These ΔT estimates, along with independent proxy and vegetation data, depict a dramatically warmer version of the Arctic. Some of this warming was likely driven by global atmospheric change and feedbacks that are possible in the modern‐day Arctic. However, transformation of the once‐contiguous Arctic landmass into a dissected archipelago has undoubtedly changed the nature and future warming potential of the Canadian Arctic region. Investigations aimed at disentangling the relative contribution of global versus regional boundary conditions to Neogene Arctic climate warming are needed to understand the extent to which these reconstructions may foreshadow conditions in the future.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.004 | 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 teacher head, 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".