Mid-Holocene climate at mid-latitudes: assessing the impact of the Saharan greening
Bibliographic record
Abstract
Abstract. During the first half of the Holocene (11,000 to 5,000 years ago) the Northern Hemisphere experienced a strengthening of the monsoonal regime, with climate reconstructions robustly suggesting a greening of the Sahara region. Paleoclimate archives also show that this so-called African Humid Period (AHP) was accompanied by changes in the climate conditions at mid to high latitudes. However, inconsistencies still exist in reconstructions of the mid-Holocene (MH) climate at mid-latitudes, and model simulations provide limited support to reduce these discrepancies. In this paper, a set of simulations performed with a climate model is used to investigate the hitherto unexplored impact of the Saharan greening on mid-latitude atmospheric circulation during the MH. Numerical simulations show a year-round impact of the Saharan greening on the main circulation features in the Northern Hemisphere, especially during boreal summer when the African monsoon develops. Key findings include a westward shift of the global Walker Circulation, leading to a modification of the North Atlantic jet stream in summer and the North Pacific jet stream in winter. Furthermore, the Saharan greening modifies the atmospheric synoptic circulation over the North Atlantic, transitioning the North Atlantic Oscillation phase from prevailingly positive to neutral-to-negative in winter and summer. This study provides a first constraint on the Saharan greening influence on northern midlatitudes, indicating new opportunities for understanding the MH climate anomalies in regions such as North America and Eurasia.
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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 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 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".