Climatic variations and societies in Northwest Alaska (11th-13th centuries CE) : contributions of dendrochronological, dendroclimatic and dendroisotopic approaches
Bibliographic record
Abstract
At the onset of the 2nd millennium CE, during the Medieval Climate Anomaly [MCA] (10th-13th centuries) and the transition to the Little Ice Age [LIA] (13th-15th centuries), the Thule culture (1200-1800 CE), directly ancestral to the Iñupiaq culture in northwest Alaska, originated in the Birnirk and Punuk cultures in the Bering Strait region. Despite extensive archaeological research since the 1920s, the spatio- temporal dynamics of these cultures remain poorly understood in northwestern Alaska. The scarcity of local climatic and environmental indicators and their low resolution, both in time and space, limit our understanding of the complex human-environment interactions at this pivotal period in the emergence of Inuit culture. The exceptional preservation of Birnirk and Thule architectural wood remains along northern coastal Alaska provides an ideal context for high-resolution dendroarchaeological studies (analysis of annual growth rings in archaeological wood). Combining conventional dendrochronology and dendroclimatology with innovative methods (δ18O dating, 14C wiggle-matching, carbon δ13C and oxygen δ18O isotope dendroclimatology), I analyzed 284 architectural timbers (Picea glauca) from six sites of northern and northwestern Alaska. The aim was to refine the chronological and climatic framework of cultural transformations in the early 2nd millennium CE in the region. By constructing annual and local climatic sequences, my doctoral work sought to reconstruct the climatic variations of the MCA and the transition to the LIA (amplitudes, frequencies, rhythm of variations) and discuss their effects on the environment in which the Birnirk, Punuk and Thule groups developed. Conventional dendrochronological analyses allowed building mean sequences (composed of several wood samples) and strengthening the network of dendrochronological sequences contributing to the millennial chronology of northwest Alaska. For the 10-11th centuries, the number of samples contributing to the chronology was multiplied by four. Variations in ring widths in this chronology are partly linked to a summer temperature index that documents low-frequency Picea glauca growth trends over the last millennium. Two isotopic chronologies δ13C and δ18O were built for the periods 1945 to 2002 and 935 to 1157 CE from six modern driftwood and five archaeological wood samples from Cape Espenberg. The δ18O chronology allowed for the reconstruction of a standardized precipitation and evapotranspiration index (SPEI4) for the month of July from 1042 to 1123 CE. This reconstruction indicates wetter conditions during the ACM with their gradual drying out from moderately wet to normal, neither wet nor dry. A wiggle-matching procedure (14C dating and Bayesian statistics) placed in calendar time 22 wood remains that conventional dendrochronology could not date. The δ18O dating approach, made possible by the newly built δ18O chronology, now a reference for northwest Alaska, provided encouraging results, but stressed out the necessity to further develop the isotopic chronology and strengthen it with a larger number of trees. These new data hold great potential for contextualizing the cultural dynamics of ancient Inuit societies in their environment at annual or decadal temporal resolution, analyzing the effects of local climate variations on resource availability and subsistence strategies, and improving our understanding of the socio-environmental dynamics at a time of major cultural transformation.
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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 | 0.002 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| 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".