Dendroclimatic reconstruction of maximum summer temperatures from upper treeline sites in Interior British Columbia, Canada
Bibliographic record
Abstract
Two independent reconstructions of maximum May–August temperatures are developed from a new network of Engelmann spruce tree-ring chronologies at treeline sites across Interior British Columbia (IBC). The IBC reconstruction (ad 1600–1997) uses the longest three ring-width (RW) and two maximum latewood density (MXD) chronologies from the region. The shorter (regional) reconstruction (REG, 1845–1997) is based on an independent, more broadly based network of chronologies (12 RW and 5 MXD) and verifies the regional signal in the parsimoniously sampled IBC reconstruction. Both models explain 53% of the regional temperature variance (1912–1995) and correlate strongly (r = 0.92) over their common period. The IBC reconstruction indicates two prolonged cooler intervals, c. 1620–1710 and 1775–1880, separated by warmer conditions that approached late twentieth-century normals between c. 1710 and 1730. The mean anomaly over the 1600–1900 period is estimated at 0.38°C below the 1961–1990 mean with the seventeenth century (1601–1700) being marginally colder than the nineteenth century (–0.53: –0.49°C). Both reconstructions model the rise in temperatures from the 1880s to 1940s and indicate that maximum summer temperatures since 1930 have been warmer than at any period since 1600. The IBC record from 1600–1900 is very similar to the mean summer-temperature record reconstructed in the adjacent Canadian Rockies, providing mutual verification for the regional nature of the signal in both reconstructions. This is the first maximum summer-temperature reconstruction from North America. Significant changes are also noted in the relationships between summer mean, maximum and minimum temperatures in this region in the last few decades with a greater absolute rate of increase in mean and minimum temperatures. These changing relationships suggest it is prudent to model tree-ring response to a variety of temperature parameters rather than using mean-temperature values.
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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 | 0.004 | 0.006 |
| Science and technology studies | 0.002 | 0.000 |
| Scholarly communication | 0.002 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 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".