Underestimation of Anthropogenic CHBr3 Emissions: Implications for Ozone Depletion
Bibliographic record
Abstract
Bromoform (CHBr3), a recognized contributor to stratospheric ozone depletion, has been largely exempt from the Montreal Protocol's regulation due to its short atmospheric lifetime and large natural emissions. Using our recent CHBr3 emission inventory containing both natural and anthropogenic sources, we reevaluated the role played by the latter in the total CHBr3 flux into the Northern Hemisphere extratropical stratosphere. Derived mainly from ship ballast, power plant cooling and desalination plant brine water, these anthropogenic sources suggest a substantial underestimation in previous global CHBr3 emission estimates. Anthropogenic sources have been underestimated by 31.5% globally, and more alarmingly, this underestimation escalates to 70.5% when focusing on the Northern Hemisphere. Consequently, atmospheric CHBr3 concentrations are also significantly higher than previous estimates, especially over the NH extratropics during boreal winter. The ODP-weighted emissions in the NH based on historical ECMWF meteorology are ~28.2 Gg Br/year, increased by ~78% above previous estimates, suggesting a more significant contribution of anthropogenic CHBr3 to stratospheric ozone depletion, especially in the NH lowermost stratosphere. To study the potential impact of these revised emission inventories, we employ the Whole Atmosphere Community Climate Model (WACCM), which enables us to project the future ozone depletion from CHBr3 under climate change scenarios and evaluate the necessity for regulatory measures to manage anthropogenic sources.
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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 | 0.002 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| 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".