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Journal Articles Atmospheric Chemistry and Physics Year : 2018

Estimates of ozone return dates from Chemistry-Climate Model Initiative simulations

1 SEE - School of Earth and Environment [Leeds]
2 NCAR - National Center for Atmospheric Research [Boulder]
3 ENEA - Agenzia Nazionale per le nuove Tecnologie, l’energia e lo sviluppo economico sostenibile = Italian National Agency for New Technologies, Energy and Sustainable Economic Development
4 Department of Meteorology [Reading]
5 Department of Chemistry [Cambridge, UK]
6 NCAS - National Centre for Atmospheric Science [Leeds]
7 NIES - National Institute for Environmental Studies
9 IMK-ASF - Institut für Meteorologie und Klimaforschung - Atmosphärische Spurengase und Fernerkundung
10 MOHC - Met Office Hadley Centre for Climate Change
11 IPA - DLR Institut für Physik der Atmosphäre
12 MRI - Meteorological Research Institute [Tsukuba]
13 GSFC - NASA Goddard Space Flight Center
14 GFDL - NOAA Geophysical Fluid Dynamics Laboratory
15 CNRM - Centre national de recherches météorologiques
16 SCC - Steinbuch Centre for Computing [Karlsruhe]
17 Institut für Meteorologie [Berlin]
18 Bodeker Scientific
19 AOS Program - Atmospheric and Oceanic Sciences Program [Princeton]
20 DSFC - Department of Physical and Chemical Sciences [L'Aquila]
21 Centre of Excellence CETEMPS
22 NIWA - National Institute of Water and Atmospheric Research [Lauder]
23 CCCma - Canadian Centre for Climate Modelling and Analysis
24 Centre for Atmospheric Science [Cambridge, UK]
25 IAC - Institute for Atmospheric and Climate Science [Zürich]
26 PMOD/WRC - Physikalisch-Meteorologisches Observatorium Davos/World Radiation Center
27 ARC Centre of Excellence for Climate System Science
28 School of Earth Sciences [Melbourne]
29 MIT - Massachusetts Institute of Technology
30 Graduate School of Environmental Studies [Nagoya]
31 JAMSTEC - Japan Agency for Marine-Earth Science and Technology
32 ACOML - Atmospheric Chemistry Observations and Modeling Laboratory
Slimane Bekki
Birgit Hassler
  • Function : Author
  • PersonId : 989495
Rong Ming Hu
  • Function : Author
Jared Lewis
  • Function : Author
Marion Marchand
Daniele Visioni


We analyse simulations performed for the Chemistry-Climate Model Initiative (CCMI) to estimate the return dates of the stratospheric ozone layer from depletion caused by anthropogenic stratospheric chlorine and bromine. We consider a total of 155 simulations from 20 models, including a range of sensitivity studies which examine the impact of climate change on ozone recovery. For the control simulations (unconstrained by nudging towards analysed meteorology) there is a large spread (±20 DU in the global average) in the predictions of the absolute ozone column. Therefore, the model results need to be adjusted for biases against historical data. Also, the interannual variability in the model results need to be smoothed in order to provide a reasonably narrow estimate of the range of ozone return dates. Consistent with previous studies, but here for a Representative Concentration Pathway (RCP) of 6.0, these new CCMI simulations project that global total column ozone will return to 1980 values in 2047 (with a 1-σ uncertainty of 2042–2052). At Southern Hemisphere mid-latitudes column ozone is projected to return to 1980 values in 2046 (2042–2050), and at Northern Hemisphere mid-latitudes in 2034 (2024–2044). In the polar regions, the return dates are 2062 (2055–2066) in the Antarctic in October and 2035 (2025–2040) in the Arctic in March. The earlier return dates in the NH reflect the larger sensitivity to dynamical changes. Our estimates of return dates are later than those presented in the 2014 Ozone Assessment by approximately 5–15 years, depending on the region. In the tropics only around half the models predict a return to 1980 values, at around 2040, while the other half do not reach this value. All models show a negative trend in tropical total column ozone towards the end of the 21st century. The CCMI models generally agree in their simulation of the time evolution of stratospheric chlorine, which is the main driver of ozone loss and recovery. However, there are a few outliers which show that the multi-model mean results for ozone recovery are not as tightly constrained as possible. Throughout the stratosphere the spread of ozone return dates to 1980 values between models tends to correlate with the spread of the return of inorganic chlorine to 1980 values. In the upper stratosphere, greenhouse gas-induced cooling speeds up the return by about 10–20 years. In the lower stratosphere, and for the column, there is a more direct link in the timing of the return dates, especially for the large Antarctic depletion. Comparisons of total column ozone between the models is affected by different predictions of the evolution of tropospheric ozone within the same scenario, presumably due to differing treatment of tropospheric chemistry. Therefore, for many scenarios, clear conclusions can only be drawn for stratospheric ozone columns rather than the total column. As noted by previous studies, the timing of ozone recovery is affected by the evolution of N2O and CH4. However, the effect in the simulations analysed here is small and at the limit of detectability from the few realisations available for these experiments compared to internal model variability. The large increase in N2O given in RCP 6.0 extends the ozone return globally by ~ 15 years relative to N2O fixed at 1960 abundances, mainly because it allows tropical column ozone to be depleted. The effect in extratropical latitudes is much smaller. The large increase in CH4 given in the RCP 8.5 scenario compared to RCP 6.0 also changes ozone return by ~ 15 years, again mainly through its impact in the tropics. For future assessments of single forcing or combined effects of CO2, CH4, and N2O on the stratospheric column ozone return dates, this work suggests that is more important to have multi-member (at least 3) ensembles for each scenario from each established participating model, rather than a large number of individual models.
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Dates and versions

insu-01702481 , version 1 (15-11-2020)





Sandip Dhomse, Douglas Kinnison, Martyn P. Chipperfield, Irene Cionni, Michaela Hegglin, et al.. Estimates of ozone return dates from Chemistry-Climate Model Initiative simulations. Atmospheric Chemistry and Physics, 2018, 18 (11), pp.8409-8438. ⟨10.5194/acp-18-8409-2018⟩. ⟨insu-01702481⟩
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