Impact of a realistic Greenland ice sheet melting on the North Atlantic over the period 1920-2014
Bibliographic record
Abstract
Greenland experienced intensive melting over the last century, especially in the 1920s and over the last decades. The supplementary input into the ocean is influencing the freshwater budget of the North Atlantic. Simultaneously, some signs of a recent weakening of the Atlantic meridional overturning circulation (AMOC) have been reported. In order to better understand the possible impact of the melting on the North Atlantic circulation, salinity and temperature trends, we construct an observation-based estimate of the freshwater fluxes from 1840 to 2014 associated to the runoff fluxes from Greenland ice sheet and surrounding glaciers and ice caps. Input from iceberg melting is also included and spatially distributed over the North Atlantic following an observed climatology. We force historical simulations of the IPSL-CM6A-LR coupled climate model with this reconstruction from 1920 to 2014. The 10-member ensemble mean displays freshened and cooled waters around Greenland, which spread in the subpolar gyre, and then towards the subtropical gyre and the Nordic Seas. Over the whole period, the convection is reduced in the Labrador and Nordic Seas, while it is slightly enhanced in the Irminger Sea, and the AMOC is reduced by 0.32±0.35 Sv at 26°N. This highlights that the AMOC decrease due to Greenland melting remains modest in these simulations and can only explain a very moderate amount of the 3±1 Sv weakening suggested in a recent study. The multi-decadal trend of the North Atlantic surface temperature obtained with the additional freshwater forcing is more in line with observations than in standard historical simulations. We also show a clear improvement of the representation of the 1995 abrupt warming in the subpolar gyre in the melting ensemble, which may thus be partly forced by Greenland ice sheet melting. Mechanisms at play imply changes in the variability of the AMOC in the melting ensemble as compared to the historical one. Such an impact on forced decadal variability has crucial consequences for decadal prediction systems that may gain skill by including observed Greenland ice sheet melting.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".