https://www.nature.com/articles/d41586-023-00687-w Skip to main content Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript. Advertisement Advertisement Nature * View all journals * Search * Log in * Explore content * About the journal * Publish with us * Subscribe * Sign up for alerts * RSS feed 1. nature 2. news 3. article * NEWS * 08 March 2023 Australia's massive wildfires shredded the ozone layer -- now scientists know why Smoke from the catastrophic 2019-20 fires unleashed ozone-eating chlorine molecules into the stratosphere. * Dyani Lewis 1. Dyani Lewis View author publications You can also search for this author in PubMed Google Scholar * Twitter * Facebook * Email You have full access to this article via your institution. Download PDF A firefighter stands in front of a bushfire at night Chemicals released during wildfires in Australia damaged the ozone layer.Credit: David Gray/Getty Massive wildfires that raged across southeast Australia in 2019-20 unleashed chemicals that chewed through the ozone layer, expanding and prolonging the ozone hole. A study, published today in Nature, describes how smoke combined with chlorine-containing molecules in the stratosphere -- remnants of chemicals that are now banned -- to cause the destruction^1. The Australian fires produced the largest smoke plume on record, releasing roughly one million tonnes of smoke to heights of up to 30 kilometres. That's well into the stratosphere, the portion of the atmosphere that contains the ozone layer, which protects Earth from harmful ultraviolet rays, says study co-author Kane Stone, an atmospheric chemist at the Massachusetts Institute of Technology (MIT) in Cambridge. In the months after the wildfires, the hole in the ozone layer, which appears annually over Antarctica, was larger and lasted longer than in previous years. But Stone says that researchers didn't know why. Altered chemistry Study co-author Susan Solomon, an atmospheric chemist also at MIT, suggests the smoke might have caused a chemical reaction that usually needs cold conditions to occur in warm air. Satellite data after the fires revealed that the levels of hydrochloric acid were especially low compared to other years in regions of the atmosphere away from the South Pole at warmer latitudes. The stratosphere "looked like another planet after those fires", she says. About 80% of the chlorine in the atmosphere is a legacy of chlorofluorocarbons, chemicals used in aerosol sprays and as refrigerants starting in the 1930s. Their use has mostly been phased out since an international treaty was implemented in 1987. Remnant chlorine is bound up as hydrochloric acid and chlorine nitrate, which are harmless to the ozone layer. But when hydrochloric acid dissolves in water droplets, it forms reactive ozone-depleting molecules. That doesn't usually happen away from the poles, because the air is too warm, says Stone. The team used a computer model to predict how various organic acids contained in smoke particles would alter the solubility of hydrochloric acid. The changes produced in the simulations mirrored the changes to stratospheric chemistry that were observed after the fires. Solomon says that hydrochloric acid latches onto the surface of the smoke particles and reacts with other molecules to produce molecular chlorine, which is broken down in sunlight to highly reactive 'ozone-eating' chlorine ions. "Wildfire smoke at warm temperatures does things over Australia that couldn't otherwise happen," says Solomon. Jim Haywood, an atmospheric scientist at the University of Exeter, UK, says that hydrochloric acid solubility in the wake of fires hasn't been investigated previously. "It does seem to be a big missing piece of the puzzle," he says. Ozone recovery at risk Chlorine-containing molecules that remain from before they were banned are slowly decaying and the annual ozone hole is shrinking. But Solomon says that more-frequent wildfires resulting from climate change could imperil the recovery of the ozone layer. "It's like a race," she says. "Does the chlorine decay out of the stratosphere fast enough in the next, say, 40-50 years that the likely increase in intense and frequent wildfires doesn't end up prolonging the ozone hole?" Not all wildfire smoke reaches the stratosphere, says David Peterson, a meteorologist at the US Naval Research Laboratory in Monterey, California. But when an intense fire combines with moist air overhead, fire-driven thunderstorms form chimney-like clouds that pump the smoke high into the atmosphere. Understanding what causes some tall storm clouds to inject smoke all the way into the stratosphere will be crucial to figuring out how much of an impact fires will have on ozone recovery, he says. Haywood would like to see the new chemistry integrated into a climate model to forecast how ozone depletion might be affected if intense wildfires become more common. doi: https://doi.org/10.1038/d41586-023-00687-w References 1. Solomon, S. et al. Nature https://doi.org/10.1038/ s41586-022-05683-0 (2023). Article Google Scholar Download references Related Articles * [d41586-023] Australian bush fires belched out immense quantity of carbon * [d41586-023] Bush-fire smoke linked to hundreds of deaths * [d41586-023] Ozone hole's healing triggers winds of change Subjects * Chemistry * Atmospheric science Latest on: Chemistry How wildfires deplete ozone in the stratosphere How wildfires deplete ozone in the stratosphere News & Views 08 MAR 23 Chlorine activation and enhanced ozone depletion induced by wildfire aerosol Chlorine activation and enhanced ozone depletion induced by wildfire aerosol Article 08 MAR 23 Chemistry course corrections tackle bias Chemistry course corrections tackle bias Career Feature 06 MAR 23 Atmospheric science Japan's rising research stars: Yuuki Wada Japan's rising research stars: Yuuki Wada Nature Index 08 MAR 23 How wildfires deplete ozone in the stratosphere How wildfires deplete ozone in the stratosphere News & Views 08 MAR 23 Oceanic climate changes threaten the sustainability of Asia's water tower Oceanic climate changes threaten the sustainability of Asia's water tower Article 01 MAR 23 Nature Careers Jobs * Research Scientist - Chemistry Research & Innovation MRC National Institute for Medical Research Harwell Campus, Oxfordshire, United Kingdom * POST-DOC POSITIONS IN THE FIELD OF "Automated Miniaturized Chemistry" supervised by Prof. Alexander Domling Palacky University (PU) Olomouc, Czech Republic * Ph.D. POSITIONS IN THE FIELD OF "Automated miniaturized chemistry" supervised by Prof. Alexander Domling Palacky University (PU) Olomouc, Czech Republic * Czech Advanced Technology and Research Institute opens A SENIOR RESEARCHER POSITION IN THE FIELD OF "Automated miniaturized chemistry" supervised by Prof. Alexander Domling Palacky University (PU) Olomouc, Czech Republic You have full access to this article via your institution. Download PDF Related Articles * [d41586-023] Australian bush fires belched out immense quantity of carbon * [d41586-023] Bush-fire smoke linked to hundreds of deaths * [d41586-023] Ozone hole's healing triggers winds of change Subjects * Chemistry * Atmospheric science Advertisement Sign up to Nature Briefing An essential round-up of science news, opinion and analysis, delivered to your inbox every weekday. Email address [ ] [ ] Yes! Sign me up to receive the daily Nature Briefing email. I agree my information will be processed in accordance with the Nature and Springer Nature Limited Privacy Policy. Sign up * Close Nature Briefing Sign up for the Nature Briefing newsletter -- what matters in science, free to your inbox daily. Email address [ ] Sign up [ ] I agree my information will be processed in accordance with the Nature and Springer Nature Limited Privacy Policy. Close Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing Explore content * Research articles * News * Opinion * Research Analysis * Careers * Books & Culture * Podcasts * Videos * Current issue * Browse issues * Collections * Subjects * Follow us on Facebook * Follow us on Twitter * Subscribe * Sign up for alerts * RSS feed About the journal * Journal Staff * About the Editors * Journal Information * Our publishing models * Editorial Values Statement * Journal Metrics * Awards * Contact * Editorial policies * History of Nature * Send a news tip Publish with us * For Authors * For Referees * Language editing services * Submit manuscript Search Search articles by subject, keyword or author [ ] Show results from [All journals] Search Advanced search Quick links * Explore articles by subject * Find a job * Guide to authors * Editorial policies Nature (Nature) ISSN 1476-4687 (online) ISSN 0028-0836 (print) nature.com sitemap About Nature Portfolio * About us * Press releases * Press office * Contact us Discover content * Journals A-Z * Articles by subject * Nano * Protocol Exchange * Nature Index Publishing policies * Nature portfolio policies * Open access Author & Researcher services * Reprints & permissions * Research data * Language editing * Scientific editing * Nature Masterclasses * Nature Research Academies * Research Solutions Libraries & institutions * Librarian service & tools * Librarian portal * Open research * Recommend to library Advertising & partnerships * Advertising * Partnerships & Services * Media kits * Branded content Career development * Nature Careers * Nature Conferences * Nature events Regional websites * Nature Africa * Nature China * Nature India * Nature Italy * Nature Japan * Nature Korea * Nature Middle East * Privacy Policy * Use of cookies * Manage cookies/Do not sell my data * Legal notice * Accessibility statement * Terms & Conditions * California Privacy Statement Springer Nature (c) 2023 Springer Nature Limited