Ocean Outgassing of Methyl Chloroform as an Underestimated Source of Emission
Bibliographic record
Abstract
Methyl chloroform (MCF) is a synthetic ozone-depleting substance used as an industrial solvent. Its primary sink is reaction with the hydroxyl radical (OH), making it a key tracer for estimating atmospheric oxidative capacity. Following Montreal Protocol regulations, MCF emissions declined rapidly after the 1990s. However, the recent slowdown in atmospheric MCF decay suggests persistent emissions and/or declining OH (contradicting chemistry-climate models projecting increasing OH). The air-sea exchange of MCF has been poorly constrained due to limited observations and simplified ocean representations. We simulate oceanic MCF fluxes using a modern ocean reanalysis and validate with depth-resolved observations. Results suggest the ocean has shifted from a net sink to a net source around 2005, outgassing 0.5 Gg yr-1 in the 2010s (up to 30% of inferred MCF emissions). This ocean outgas is an order of magnitude larger than previous estimates and can have important implications for interpreting OH levels from MCF records.
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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 | 0.001 |
| 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".