The Montreal Protocol is successfully protecting the ozone layer. The main halogen gases responsible for stratospheric ozone depletion have been regulated under the Protocol, their combined atmospheric abundances are declining and ozone is increasing in some parts of the atmosphere1. Ozone depletion potentials2,3,4, relative measures of compounds’ abilities to deplete stratospheric ozone, have been a key regulatory component of the Protocol in successfully guiding the phasing out in the manufacture of the most highly depleting substances. However, this latest, recovery phase in monitoring the success of the Protocol calls for further metrics. The ‘delay in ozone return’ has been widely used to indicate the effect of different emissions or phase-down strategies, but we argue here that it can sometimes be ambiguous or even of no use. Instead, we propose the use of an integrated ozone depletion (IOD) metric to indicate the impact of any new emission. The IOD measures the time-integrated column ozone depletion and depends only on the emission strength and the whole atmosphere and stratospheric lifetimes of the species considered. It provides a useful complementary metric of the impact of specific emissions of an ozone depleting substance for both the scientific and policy communities.
This is a preview of subscription content, access via your institution
Access Nature and 54 other Nature Portfolio journals
Get Nature+, our best-value online-access subscription
$29.99 / 30 days
cancel any time
Subscribe to this journal
Receive 51 print issues and online access
$199.00 per year
only $3.90 per issue
Rent or buy this article
Prices vary by article type
Prices may be subject to local taxes which are calculated during checkout
The UM-UKCA model is available for use under licence. Several research organizations and national meteorological services use the UM in collaboration with the Met Office to undertake basic atmospheric process research, produce forecasts, develop the UM code and build and evaluate Earth system models. For further information on how to apply for a licence see http://www.metoffice.gov.uk/research/modelling-systems/unified-model (last accessed 27 September 2021).
Scientific Assessment of Ozone Depletion: 2018, Global Ozone Research and Monitoring Project. Report No. 58 (World Meteorological Organization (WMO), 2018).
Wuebbles, D. J. Chlorocarbon emission scenarios: potential impact on stratospheric ozone. J. Geophys. Res. 88, 1433 (1983).
Solomon, S. & Albritton, D. L. Time-dependent ozone depletion potentials for short- and long-term forecasts. Nature 357, 33–37 (1992).
Solomon, S., Mills, M., Heidt, L. E., Pollock, W. H. & Tuck, A. F. On the evaluation of ozone depletion potentials. J. Geophys. Res. 97, 825–842 (1992).
Newchurch, M. J. et al. Evidence for slowdown in stratospheric ozone loss: first stage 643 of ozone recovery. J. Geophys. Res. 108, 4507 (2003).
Yang, E.-S. et al. First stage of Antarctic ozone recovery. J. Geophys. Res. 113, D20308 (2008).
Solomon, S. et al. Emergence of healing in the Antarctic ozone layer. Science 353, 269–274 (2016).
Weber, M. et al. Total ozone trends from 1979 to 2016 derived from five merged observational datasets—the emergence into ozone recovery. Atmos. Chem. Phys. 18, 2097–2117 (2018).
Petropavlovskikh, I. et al. (eds) LOTUS: SPARC/IO3C/GAW Report on Long-Term Ozone Trends and Uncertainties in the Stratosphere. SPARC Report No. 9, WCRP-17/2018, GAW Report No. 241 (SPARC, 2019); https://doi.org/10.17874/f899e57a20b
Montzka, S. A. et al. An unexpected and persistent increase in global emissions of ozone-depleting CFC-11. Nature 557, 413–417 (2018).
Rigby, M. et al. Increase in CFC-11 emissions from eastern China based on atmospheric observations. Nature 569, 546–550 (2019).
Hossaini, R. et al. The increasing threat to stratospheric ozone from dichloromethane. Nat. Commun. 8, 15962 (2017).
Fang, X. et al. Rapid increase in ozone-depleting chloroform emissions from China. Nat. Geosci. 12, 89–93 (2019).
Scientific Assessment of Ozone Depletion: 2006, Global Ozone Research and Monitoring Project. Report No. 50 (World Meteorological Organization (WMO), 2007).
Chipperfield, M. P. et al. Detecting recovery of the stratospheric ozone layer. Nature 549, 211–218 (2017).
Keeble, J., Brown, H., Abraham, N. L., Harris, N. R. P. & Pyle, J. A. On ozone trend detection: using coupled chemistry-climate simulations to investigate early signs of total column ozone recovery. Atmos. Chem. Phys. 18, 7625–7637 (2018).
Montzka, S. A. et al. A sharp decline in global CFC-11 emissions during 2018–2019. Nature 590, 428–432 (2021).
Oram, D. et al. A growing threat to the ozone layer from short-lived anthropogenic chlorocarbons. Atmos. Chem. Phys. 17, 11929–11941 (2017).
Scientific Assessment of Ozone Depletion: 2014, Global Ozone Research and Monitoring Project. Report No. 55 (World Meteorological Organization (WMO), 2014).
Fioletov, V. E. et al. Global and zonal total ozone variations estimated from ground-based and satellite measurements: 1964–2000. J. Geophys. Res. https://doi.org/10.1029/2001JD001350 (2002).
McKenzie, R. & Madronich, S. in Encyclopedia of Atmospheric Sciences 2nd edn, Vol. 5 (Academic Press, 2014).
Klobas, J. E. et al. Reformulating the bromine alpha factor and equivalent effective stratospheric chlorine (EESC): evolution of ozone destruction rates of bromine and chlorine in future climate scenarios. Atmos. Chem. Phys. 20, 9459–9471 (2020).
Waugh, D. W. & Hall, T. Age of stratospheric air: theory, observations, and models. Rev. Geophys. https://doi.org/10.1029/2000RG000101 (2002).
Stiller, G. P. et al. Global distribution of mean age of stratospheric air from MIPAS SF6 measurements. Atmos. Chem. Phys. 8, 677–695 (2008).
Keeble, J. et al. Modelling the potential impacts of the recent, unexpected increase in CFC-11 emissions on total column ozone recovery. Atmos. Chem. Phys. 20, 7153–7166 (2020).
Dameris, M., Jöckel, P. & Nützel, M. Possible implications of enhanced chlorofluorocarbon-11 concentrations on ozone. Atmos. Chem. Phys. 19, 13759–13771 (2019).
Dhomse, S. S. et al. Delay in recovery of the Antarctic ozone hole from unexpected CFC-11 emissions. Nat. Commun. 10, 5781 (2019).
Claxton, T. et al. A synthesis inversion to constrain global emissions of two very short-lived chlorocarbons: dichloromethane, and perchloroethylene. J. Geophys. Res.: Atmospheres 125, e2019JD031818 (2020).
Claxton, T., Hossaini, R., Wild, O., Chipperfield, M. P. & Wilson, C. On the regional and seasonal ozone depletion potential of chlorinated very short‐lived substances. Geophys. Res. Letts. 46, 5489–5498 (2019).
Scientific Assessment of Ozone Depletion: 2002, Global Ozone Research and Monitoring Project. Report No. 47 (World Meteorological Organization (WMO), 2003).
Hewitt, H. T. et al. Design and implementation of the infrastructure of HadGEM3: the next-generation Met Office climate modelling system. Geosci. Model Dev. 4, 223–253 (2011).
Bednarz, E. M. et al. Future Arctic ozone recovery: the importance of chemistry and dynamics. Atmos. Chem. Phys. 16, 12159–12176 (2016).
Eyring, V. et al. Overview of IGAC/SPARC Chemistry-Climate Model Initiative (CCMI) community simulations in support of upcoming ozone and climate assessments. SPARC Newsletter 40, 48–66 (2013).
Dhomse, S. S. et al. Estimates of ozone return dates from Chemistry-Climate Model Initiative simulations. Atmos. Chem. Phys. 18, 8409–8438 (2018).
J.A.P, J.K., N.L.A. and P.T.G. were financially supported by NERC through NCAS (grant no. R8/H12/83/003). M.P.C. was supported by NERC through the grant nos. NE/R001782/1 (SISLAC) and NE/V011863/1 (LSO3). Model simulations have been performed using the ARCHER UK National Supercomputing Service. This work used the UK Research Data Facility (http://www.archer.ac.uk/documentation/rdf-guide, last accessed 2 June 2021). This work used JASMIN, the UK collaborative data analysis facility.
The authors declare no competing interests.
Peer review information
Nature thanks the anonymous reviewers for their contribution to the peer review of this work. Peer reviewer reports are available.
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Extended data figures and tables
Extended Data Fig. 1 Time series, from 1960 to 2100, of total column ozone (TCO, DU), averaged from 90°S-90°N, from the simulations analysed in this study.
Part a) plots annual mean model data and b) plots the data after it has been smoothed using an 11-point boxcar smoothing, following Dhomse et al34. The large difference at 2100 between Base and the scenario with 30-year emissions of CFC-11 and CFC-12 arises from the large increase in (and subsequent emission from) their banks, assumed in that scenario (as discussed in Keeble et al.25).
Extended Data Fig. 2 Integrated ozone depletion (IOD, in DU years) from all UM-UKCA integrations plotted against the total halogen emission in Tg Cl, EEq, multiplied by the whole atmosphere lifetime of the emitted species divided by its stratospheric lifetime, for comparison with Figure 3.
The IOD for short-lived gases is calculated over the perturbation period as defined in the text, otherwise as in Figure 3. The correlation coefficient, r, is now 0.90, and when the scenario with the emission of CFC-11 and CFC-12 is not included, the correlation coefficient remains high (0.83).
About this article
Cite this article
Pyle, J.A., Keeble, J., Abraham, N.L. et al. Integrated ozone depletion as a metric for ozone recovery. Nature 608, 719–723 (2022). https://doi.org/10.1038/s41586-022-04968-8
This article is cited by
Nature Geoscience (2023)