{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,30]],"date-time":"2026-07-30T09:59:02Z","timestamp":1785405542727,"version":"3.56.0"},"reference-count":59,"publisher":"National Academy of Sciences","issue":"28","license":[{"start":{"date-parts":[[2026,6,29]],"date-time":"2026-06-29T00:00:00Z","timestamp":1782691200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"NSF AGS","award":["2128617"],"award-info":[{"award-number":["2128617"]}]},{"name":"NSF AGS","award":["2316980"],"award-info":[{"award-number":["2316980"]}]},{"name":"NOAA Science Collaboration Program","award":["NA23OAR4310383B"],"award-info":[{"award-number":["NA23OAR4310383B"]}]},{"name":"NSF AGS","award":["2202812"],"award-info":[{"award-number":["2202812"]}]},{"name":"ERC Starting Grant","award":["101070127"],"award-info":[{"award-number":["101070127"]}]}],"content-domain":{"domain":["www.pnas.org"],"crossmark-restriction":true},"short-container-title":["Proc. Natl. Acad. Sci. U.S.A."],"published-print":{"date-parts":[[2026,7,14]]},"abstract":"<jats:p>\n                    The Antarctic ozone hole was first reported in 1985, and small ozone losses at the global scale were also observed in the late 1980s. The combination of field and laboratory measurements, together with modeling, quickly established anthropogenic chlorofluorocarbons (CFCs) as the cause of both the Antarctic and global ozone depletion. However, when, where, and why the earliest ozone depletion could have been detected has not been determined. Here, we conduct a thought experiment to investigate when human-induced ozone depletion could have first been detectable, assuming the availability of accurate stratospheric ozone observations from 1950 onward. We find that human-caused ozone depletion was likely identifiable as early as 1957 in the tropical upper stratosphere. This region\u2019s low internal variability enables the earliest detection of the anthropogenic signal, even though tropical ozone losses in the upper stratosphere were smaller than those in higher-latitude regions. Our results highlight the key role of considering both internal variability (\u201cnoise\u201d) and the forced response (\u201csignal\u201d) in detection studies. Further, while CFCs are widely recognized as the primary drivers of current ozone depletion, we find that early ozone loss was primarily caused by human-made carbon tetrachloride (CCl\n                    <jats:sub>4<\/jats:sub>\n                    ), used mainly as a solvent. These findings suggest that a clear human influence on the stratospheric ozone layer began nearly 70 y ago, even before substantial emissions of CFCs from spray cans or air conditioning.\n                  <\/jats:p>","DOI":"10.1073\/pnas.2608286123","type":"journal-article","created":{"date-parts":[[2026,6,29]],"date-time":"2026-06-29T19:11:46Z","timestamp":1782760306000},"update-policy":"https:\/\/doi.org\/10.1073\/pnas.cm10313","source":"Crossref","is-referenced-by-count":1,"title":["The emergence of human influence on the ozone layer by the 1960s"],"prefix":"10.1073","volume":"123","author":[{"ORCID":"https:\/\/orcid.org\/0009-0008-8319-4846","authenticated-orcid":false,"given":"Jian","family":"Guan","sequence":"first","affiliation":[{"id":[{"id":"https:\/\/ror.org\/042nb2s44","id-type":"ROR","asserted-by":"publisher"}],"name":"Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of 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Atmospheric Ozone 1985: Assessment of Our Understanding of the Processes Controlling Its Present Distribution and Change. Global Ozone Research and Monitoring Project\u2014Report No. 16. Geneva Switzerland: World Meteorological Organization (1985)."},{"key":"e_1_3_4_5_2","unstructured":"World Meteorological Organization. Report of the International Ozone Trends Panel 1988. Global Ozone Research and Monitoring Project\u2014Report No. 18. Geneva Switzerland: World Meteorological Organization (1988)."},{"key":"e_1_3_4_6_2","unstructured":"J. C. Laube S. Tegtmeier. Chapter 1: Update on ozone-depleting substances (ODSs) and other gases of interest to the Montreal Protocol. In Scientific Assessment of Ozone Depletion: 2022 D. W. Fahey P. A. Newman J. A. Pyle and B. Safari eds. World Meteorological Organization Geneva Switzerland 2022 pp. 51\u2013113."},{"key":"e_1_3_4_7_2","doi-asserted-by":"publisher","DOI":"10.1038\/381551a0"},{"key":"e_1_3_4_8_2","doi-asserted-by":"publisher","DOI":"10.5194\/acp-9-2113-2009"},{"key":"e_1_3_4_9_2","first-page":"153","volume-title":"Scientific Assessment of Ozone Depletion: 2022","author":"Hassler B.","unstructured":"B. Hassler, P. J. Young, \u201cChapter 3: Update on global ozone: Past, present, and future\u201d in Scientific Assessment of Ozone Depletion: 2022, D. W. Fahey, P. A. Newman, J. A. Pyle, B. Safari, eds. World Meteorological Organization, Geneva, Switzerland, 2022, pp. 153\u2013214."},{"key":"e_1_3_4_10_2","first-page":"215","volume-title":"Scientific Assessment of Ozone Depletion: 2022","author":"Chipperfield M. P.","unstructured":"M. P. Chipperfield, M. L. Santee, \u201cChapter 4: Polar stratospheric ozone: Past, present, and future\u201d in Scientific Assessment of Ozone Depletion: 2022, D. W. Fahey, P. A. 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Plummer , CCMI-2022: A new set of Chemistry-Climate Model Initiative (CCMI) community simulations to update the assessment of models and support upcoming ozone assessment activities. 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B.","year":"1926","unstructured":"G. M. B. Dobson, D. H. Harrison, Measurements of the amount of ozone in the Earth\u2019s atmosphere and its relation to other geophysical conditions. Proc. R. Soc. London. Ser. A. 110, 662\u2013693 (1926).","journal-title":"Proc. R. Soc. London. Ser. A."},{"key":"e_1_3_4_49_2","doi-asserted-by":"publisher","DOI":"10.5194\/acp-22-11657-2022"},{"key":"e_1_3_4_50_2","doi-asserted-by":"publisher","DOI":"10.5194\/acp-24-2783-2024"},{"key":"e_1_3_4_51_2","doi-asserted-by":"publisher","DOI":"10.1175\/BAMS-D-23-0281.1"},{"key":"e_1_3_4_52_2","doi-asserted-by":"publisher","DOI":"10.1088\/2752-5295\/ac9cc2"},{"key":"e_1_3_4_53_2","unstructured":"World Meteorological Organization. Scientific Assessment of Stratospheric Ozone: 1989. Global Ozone Research and Monitoring Project\u2014Report No. 20. 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Deposited 12 September 2025."}],"container-title":["Proceedings of the National Academy of Sciences"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/pnas.org\/doi\/pdf\/10.1073\/pnas.2608286123","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,6,29]],"date-time":"2026-06-29T19:11:54Z","timestamp":1782760314000},"score":1,"resource":{"primary":{"URL":"https:\/\/pnas.org\/doi\/10.1073\/pnas.2608286123"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,6,29]]},"references-count":59,"journal-issue":{"issue":"28","published-print":{"date-parts":[[2026,7,14]]}},"alternative-id":["10.1073\/pnas.2608286123"],"URL":"https:\/\/doi.org\/10.1073\/pnas.2608286123","relation":{},"ISSN":["0027-8424","1091-6490"],"issn-type":[{"value":"0027-8424","type":"print"},{"value":"1091-6490","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,6,29]]},"assertion":[{"value":"2026-03-16","order":0,"name":"received","label":"Received","group":{"name":"publication_history","label":"Publication History"}},{"value":"2026-05-12","order":2,"name":"accepted","label":"Accepted","group":{"name":"publication_history","label":"Publication History"}},{"value":"2026-06-29","order":3,"name":"published","label":"Published","group":{"name":"publication_history","label":"Publication History"}}],"article-number":"e2608286123"}}