“World avoided” simulations with the Whole Atmosphere Community Climate Model
Bibliographic record
Abstract
We use the Whole Atmosphere Community Climate Model, coupled to a deep ocean model, to investigate the impact of continued growth of halogenated ozone depleting substances (ODS) in the absence of the Montreal Protocol. We confirm the previously reported result that the growth of ODS leads to a global collapse of the ozone layer in mid‐21st century, with column amounts falling to 100 DU or less at all latitudes. We also show that heterogeneous activation of chlorine in the lower stratosphere hastens this collapse but is not essential to produce it. The growth of ODS, which are also greenhouse gases, produces a radiative forcing of 4 W m −2 by 2070, nearly equal that of the non‐ODS greenhouse gases CO 2 , CH 4 , and N 2 O in the RCP4.5 scenario of IPCC. This leads to surface warming of over 2 K in the tropics, 6 K in the Arctic, and close to 4 K in Antarctica in 2070 compared to the beginning of the century. We explore the reversibility of these impacts following complete cessation of ODS emissions in the mid‐2050s. We find that impacts are reversed on various time scales, depending on the atmospheric lifetime of the ODS that cause them. Thus ozone in the lower stratosphere in the tropics and subtropics recovers very quickly because the ODS that release chlorine and bromine there (e.g., methyl chloroform and methyl bromide) have short atmospheric lifetimes and are removed within a few years. On the other hand, ozone depletion in the polar caps and global radiative forcing depend on longer‐lived ODS, such that much of these impacts persist through the end of our simulations in 2070.
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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 | 0.002 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.002 |
| 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 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".