Bibliographic record
Abstract
The realistic simulation of northern hemisphere glacial inceptions, which occurred during the Quaternary period, has challenged scores of climate theoreticians and modellers. After reviewing the Milankovitch theory of glaciation, a number of earlier modelling studies of the last glacial inception (LGI) which have employed either high‐resolution General Circulation Models (GCMs) or Earth system Models of Intermediate Complexity (EMICs) are described. The latter class of models has been developed over the past two decades in order to investigate the many interactions and feedbacks among the geophysical and biospheric components of the Earth system that take place over long time scales. Following a description of the McGill Paleoclimate Model (MPM) and other EMICs, some recent McGill simulations of the LGI in response to orbital (Milankovitch) and radiative (atmospheric CO2) forcings are presented. Special attention is given to determining the relative roles of the ocean's thermohaline circulation, freshwater fluxes into the ocean, orography, cryospheric processes and vegetation dynamics during the inception phase. In particular, it is shown that with the vegetation‐albedo feedback included in the model, the buildup of ice sheets over North America is larger than over Eurasia, in agreement with observations. This paper concludes with a discussion on the (possible) occurrence of the next glacial period. To address this issue, which has been inspired by recent publications of Berger and Loutre, MPM simulations of the climate for the next 100 kyr, forced by various prescribed atmospheric CO2 levels, as well as the future insolation changes as calculated by the Berger algorithm, are presented. The influence of a near‐term global warming scenario on glacial inception is also examined. If it is assumed that after such a warming scenario the concentration of CO2in the atmosphere returns to pre‐industrial levels (in the range of 280–290 ppm), then the MPM predicts that the next glacial would start at around 50 kyr after present, which is consistent with the results of Berger and Loutre. Finally, recent simulations of future glacial inceptions using the Potsdam EMIC which includes an atmosphere‐ocean carbon cycle component are described. From one of these simulations in which 5000 GtC are released into the atmosphere due to human activities, it is concluded that the current interglacial will last for at least another half‐million years because of the limited ability of the oceans to absorb such a large carbon release to the atmosphere.
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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 | 0.001 | 0.002 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.003 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.008 | 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".