CFC-11 measurements in China, Nepal, Pakistan, Saudi Arabia and South Korea (1998–2018): Urban, landfill fire and garbage burning sources
Bibliographic record
Abstract
Environmental context The production and consumption of chlorofluorocarbons (CFCs) is regulated under the Montreal Protocol and its amendments, due to their role in stratospheric ozone depletion. Global atmospheric levels of CFC-11 did not decline as rapidly as expected during 2012–2018, in large part due to emissions from eastern China. In order to further clarify global CFC-11 emissions, this work provides a rare set CFC-11 measurements from understudied countries and sources throughout Asia (1998–2018). Abstract Trichlorofluoromethane (CFC-11) is an ozone-depleting substance whose production and consumption are regulated under the Montreal Protocol. Global atmospheric CFC-11 levels declined less quickly than expected during 2012–2018, largely because of ongoing emissions from eastern Asia. Satellite measurements suggest additional CFC-11 hotspots in the Arabian Peninsula and north India/Nepal. Here we present CFC-11 levels measured in dozens of Asian cities during 1998–2018, including China and Pakistan before the 2010 phaseout of CFC-11, and China, Nepal, Pakistan, Saudi Arabia and South Korea after the phaseout. Surface measurements of CFCs in Nepal, Pakistan and Saudi Arabia are very rare, and these surveys provide important observational constraints from understudied regions. During pre-phaseout campaigns, higher CFC-11 levels were measured in Beijing than Karachi, despite much higher overall volatile organic compound (VOC) levels in Karachi. During post-phaseout campaigns, average CFC-11 levels were higher in inland Shandong Province and Seoul (1.11–1.23× background) than in western Saudi Arabia, Lahore and Kathmandu (1.02–1.11× background), despite higher levels of other VOCs in the latter regions. While China is known to emit excess CFC-11, elevated CFC-11 levels in Seoul, especially during stagnant meteorological conditions, suggest local emissions in 2015–2016. Rough emission estimates suggest that South Korea is likely a relatively minor global source of excess CFC-11. Hotspot CFC-11 levels were measured from a landfill fire in Mecca (average of 1.8× background) and from garbage burning in Nepal (1.5× background). Because garbage burning and open burning in dumps are common practices, further investigation of CFC-11 emissions at dumps and landfills worldwide is encouraged to determine their global impact.
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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 | 0.000 | 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 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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".