Changes of Glaciers and Climate in Northwestern North America during the Late Twentieth Century
Bibliographic record
Abstract
Abstract About 75% of 46 glaciers measured using repeat airborne altimetry in Alaska and northwestern Canada have been losing mass at an increasing rate from the mid-1990s to the middle of the first decade of the twenty-first century, relative to an earlier period beginning in the 1950s–70s. The remaining glaciers have been either gaining mass during the more recent period or continuing to lose mass, but at a decreasing rate. Temperature and precipitation data at 67 climate stations were examined to explain these changes. Nearly all significant changes in winter (October–April) and summer (May–September) air temperatures were positive (2.0° ± 0.8° and 1.0° ± 0.4°C) between 1950 and 2002, and all seasonally averaged values of freezing level heights (FLH) increased during the same time period. A small increase in precipitation was observed, but these changes were significant at only 17% of the stations. Regional glacier changes, modeled using mass balance sensitivities and climate station temperature and precipitation changes, agreed with observations to within the limits of reported errors. Seasonal variations in accumulation resulted in large uncertainties in the recent period mass variations. In nearly all regions, increasing summer temperatures accounted for most of the glacier mass losses. FLH variations show that the maritime glacier systems are more sensitive to variations in the mean position of the winter FLH than interior regions, suggesting that strong winter warming has affected these regions in addition to the summer changes. These measurements augment the increasingly strong evidence of late twentieth-century climate change in northwestern North America.
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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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 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) | 0.000 | 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".