The return to 1980 stratospheric halogen levels: a moving target in ozone assessments from 2006 to 2022
<p>The international scientific assessment of ozone depletion is prepared every 4 years to support decisions made by the parties to the Montreal Protocol. In each assessment an outlook of ozone recovery time is provided. The year when equivalent effective stratospheric chlorine (EESC) returns...
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Copernicus Publications
2024-11-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://acp.copernicus.org/articles/24/13081/2024/acp-24-13081-2024.pdf |
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| author | M. J. Lickley M. J. Lickley J. S. Daniel L. A. McBride L. A. McBride R. J. Salawitch R. J. Salawitch R. J. Salawitch G. J. M. Velders G. J. M. Velders |
| author_facet | M. J. Lickley M. J. Lickley J. S. Daniel L. A. McBride L. A. McBride R. J. Salawitch R. J. Salawitch R. J. Salawitch G. J. M. Velders G. J. M. Velders |
| author_sort | M. J. Lickley |
| collection | DOAJ |
| description | <p>The international scientific assessment of ozone depletion is prepared every 4 years to support decisions made by the parties to the Montreal Protocol. In each assessment an outlook of ozone recovery time is provided. The year when equivalent effective stratospheric chlorine (EESC) returns to the level found in 1980 is an important metric for the recovery of the ozone layer. Over the past five assessments, the expected date for the return of EESC to the 1980 level, for mid-latitudes, was delayed, from the year 2049 in the 2006 assessment to 2066 in the 2022 assessment, which represents a delay of 17 years over a 16-year assessment period. Here, we quantify the primary drivers that have delayed the expected EESC recovery date between each of these assessments. We find that by using identical EESC formulations, the delay between the 2006 and 2022 assessments' expected return of EESC to 1980 levels is shortened to 12.6 years. Of this delay, bank calculation methods account for <span class="inline-formula">∼</span> 4 years, changes in the assumed atmospheric lifetime for certain ozone-depleting substances (ODSs) account for <span class="inline-formula">∼</span> 3.5 years, an underestimate of the emission of carbon tetrachloride accounts for <span class="inline-formula">∼</span> 3 years, and updated historical mole fraction estimates of ODSs account for <span class="inline-formula">∼</span> 1 year. Since some of the underlying causes of these delays are amenable to future controls (e.g., capture of ODSs from banks and limitations on future feedstock emissions), it is important to understand the reasons for the delays in the expected recovery date of stratospheric halogens.</p> |
| format | Article |
| id | doaj-art-49e6c51d06fc425db1e1c338f2c261d5 |
| institution | Kabale University |
| issn | 1680-7316 1680-7324 |
| language | English |
| publishDate | 2024-11-01 |
| publisher | Copernicus Publications |
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| series | Atmospheric Chemistry and Physics |
| spelling | doaj-art-49e6c51d06fc425db1e1c338f2c261d52024-11-27T10:11:12ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242024-11-0124130811309910.5194/acp-24-13081-2024The return to 1980 stratospheric halogen levels: a moving target in ozone assessments from 2006 to 2022M. J. Lickley0M. J. Lickley1J. S. Daniel2L. A. McBride3L. A. McBride4R. J. Salawitch5R. J. Salawitch6R. J. Salawitch7G. J. M. Velders8G. J. M. Velders9The Earth Commons, Georgetown University, Washington, DC 20057, USAScience, Technology, and International Affairs, Georgetown University, Washington, DC 20057, USANOAA Chemical Sciences Laboratory, Boulder, CO 80305, USADepartment of Chemistry and Biochemistry, Albright College, Reading, PA 19612, USAnow at: Science and Technology Corporation, Columbia, MD 21046, USADepartment of Chemistry and Biochemistry, University of Maryland, College Park, MD 20740, USADepartment of Atmospheric and Oceanic Science, University of Maryland, College Park, MD 20740, USAEarth System Science Interdisciplinary Center, University of Maryland, College Park, MD 20740, USANational Institute for Public Health and the Environment (RIVM), Bilthoven, the NetherlandsInstitute for Marine and Atmospheric Research Utrecht, Utrecht University, Utrecht, the Netherlands<p>The international scientific assessment of ozone depletion is prepared every 4 years to support decisions made by the parties to the Montreal Protocol. In each assessment an outlook of ozone recovery time is provided. The year when equivalent effective stratospheric chlorine (EESC) returns to the level found in 1980 is an important metric for the recovery of the ozone layer. Over the past five assessments, the expected date for the return of EESC to the 1980 level, for mid-latitudes, was delayed, from the year 2049 in the 2006 assessment to 2066 in the 2022 assessment, which represents a delay of 17 years over a 16-year assessment period. Here, we quantify the primary drivers that have delayed the expected EESC recovery date between each of these assessments. We find that by using identical EESC formulations, the delay between the 2006 and 2022 assessments' expected return of EESC to 1980 levels is shortened to 12.6 years. Of this delay, bank calculation methods account for <span class="inline-formula">∼</span> 4 years, changes in the assumed atmospheric lifetime for certain ozone-depleting substances (ODSs) account for <span class="inline-formula">∼</span> 3.5 years, an underestimate of the emission of carbon tetrachloride accounts for <span class="inline-formula">∼</span> 3 years, and updated historical mole fraction estimates of ODSs account for <span class="inline-formula">∼</span> 1 year. Since some of the underlying causes of these delays are amenable to future controls (e.g., capture of ODSs from banks and limitations on future feedstock emissions), it is important to understand the reasons for the delays in the expected recovery date of stratospheric halogens.</p>https://acp.copernicus.org/articles/24/13081/2024/acp-24-13081-2024.pdf |
| spellingShingle | M. J. Lickley M. J. Lickley J. S. Daniel L. A. McBride L. A. McBride R. J. Salawitch R. J. Salawitch R. J. Salawitch G. J. M. Velders G. J. M. Velders The return to 1980 stratospheric halogen levels: a moving target in ozone assessments from 2006 to 2022 Atmospheric Chemistry and Physics |
| title | The return to 1980 stratospheric halogen levels: a moving target in ozone assessments from 2006 to 2022 |
| title_full | The return to 1980 stratospheric halogen levels: a moving target in ozone assessments from 2006 to 2022 |
| title_fullStr | The return to 1980 stratospheric halogen levels: a moving target in ozone assessments from 2006 to 2022 |
| title_full_unstemmed | The return to 1980 stratospheric halogen levels: a moving target in ozone assessments from 2006 to 2022 |
| title_short | The return to 1980 stratospheric halogen levels: a moving target in ozone assessments from 2006 to 2022 |
| title_sort | return to 1980 stratospheric halogen levels a moving target in ozone assessments from 2006 to 2022 |
| url | https://acp.copernicus.org/articles/24/13081/2024/acp-24-13081-2024.pdf |
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