Temporal and spatial changes of permafrost in Canada since the end of the Little Ice Age
Bibliographic record
Abstract
Climate warming was significant from the mid‐19th century to the mid‐20th century and in recent decades at most northern high latitudes. Climate warming could induce permafrost degradation, which may have important impacts on hydrological, ecological, and biogeochemical processes and on northern communities and infrastructure. To assess the effects of climate change on permafrost, a process‐based model of Northern Ecosystem Soil Temperature (NEST) was developed and utilized to simulate the ground thermal regime of the Canadian landmass at a resolution of a half‐degree latitude‐longitude since the end of the Little Ice Age (circa 1850). The simulated southern boundary of the permafrost for recent decades is similar to that of the current published map, and the simulated active layer thickness and the depth to permafrost base are comparable to site measurements. Simulation results show that climate change since the end of the Little Ice Age, especially during the 20th century, has induced degradation of permafrost in most of Canada: From the 1850s to the 1990s, the area underlain by permafrost was reduced by 5.4%; for those areas where permafrost existed in all the years throughout the period 1850–2002, the mean depth to the base of permafrost decreased (became shallower) by 3 m; the mean active layer thickness increased by 0.21 m, or 34%; and the mean depth to permafrost table increased by 0.39 m. Results also show that suprapermafrost taliks were formed and became larger and more frequent with climate warming in the southern permafrost region, which greatly enhanced permafrost thaw from the top and could have severe impacts on the landscape, hydrology, and ecosystems.
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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) | 0.000 | 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) | 0.001 | 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 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".