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Stratospheric ozone depletion and tropospheric ozone increases drive Southern Ocean interior warming

Abstract

Atmospheric ozone has undergone distinct changes in the stratosphere and troposphere during the second half of the twentieth century, with depletion in the stratosphere and an increase in the troposphere. Until now, the effect of these changes on ocean heat uptake has been unclear. Here we show that both stratospheric and tropospheric ozone changes have contributed to Southern Ocean interior warming with the latter being more important. The ozone changes between 1955 and 2000 induced about 30% of the net simulated ocean heat content increase in the upper 2,000 m of the Southern Ocean, with around 60% attributed to tropospheric increases and 40% to stratospheric depletion. Moreover, these two warming contributions show distinct physical mechanisms: tropospheric ozone increases cause a subsurface warming in the Southern Ocean primarily via the deepening of isopycnals, while stratospheric ozone causes depletion via spiciness changes along isopycnals. Our results highlight that tropospheric ozone is more than an air pollutant and, as a greenhouse gas, has been pivotal to the Southern Ocean warming.

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Fig. 1: Changes in Southern Hemisphere westerlies and Southern Ocean temperature in response to ozone changes in CMIP5 and CMIP6 simulations.
Fig. 2: Observed and simulated Southern Ocean heat content.
Fig. 3: Changes in Southern Hemisphere westerlies and Southern Ocean temperature in response to ozone changes in CanESM5 simulations.
Fig. 4: Temperature and salinity spiciness changes on density surfaces in CanESM5 ozone experiments.
Fig. 5: Surface heat flux, freshwater flux and zonal wind changes in CanESM5 ozone experiments.
Fig. 6: Spiciness and heave changes of ocean temperature in CanESM5 ozone experiments.

Data availability

All the raw CMIP5 model simulation data are publicly available at https://esgf-node.llnl.gov/search/cmip5/. All the raw CMIP6 model simulation data are publicly available at https://esgf-node.llnl.gov/projects/cmip6/. The IAP observation data are publicly available at http://www.ocean.iap.ac.cn/.

Code availability

Figures 1–6 were generated using NCL version 6.5.0 (ref. 50). The codes and processed variables to generate Figs. 1–6 are available via Zenodo at https://doi.org/10.5281/zenodo.6003088 (ref. 51).

References

  1. Farman, J. C., Gardiner, B. G. & Shanklin, J. D. Large losses of total ozone in Antarctica reveal seasonal ClOx/NOx interaction. Nature 315, 207–210 (1985).

    CAS  Google Scholar 

  2. Rowland, F. S. Chlorofluorocarbons and the depletion of stratospheric ozone. Am. Sci. 77, 36–45 (1989).

    Google Scholar 

  3. Solomon, S. Progress towards a quantitative understanding of Antarctic ozone depletion. Nature 347, 347–354 (1990).

    CAS  Google Scholar 

  4. Scientific Assessment of Ozone Depletion: 2018. Global Ozone Research and Monitoring Project—Report No. 58 (World Meteorological Organization, 2018).

  5. Young, P. J. et al. Tropospheric Ozone Assessment Report: Assessment of global-scale model performance for global and regional ozone distributions, variability, and trends. Elementa 6, 10 (2018).

    Google Scholar 

  6. Stevenson, D. S. et al. Tropospheric ozone changes, radiative forcing and attribution to emissions in the Atmospheric Chemistry and Climate Model Inter-comparison Project (ACCMIP). Atmos. Chem. Phys. 13, 3063–3085 (2013).

    Google Scholar 

  7. Cooper, O. R. et al. Global distribution and trends of tropospheric ozone: An observation-based review. Elementa 2, 000029 (2014).

    Google Scholar 

  8. Yeung, L. Y. et al. Isotopic constraint on the twentieth-century increase in tropospheric ozone. Nature 570, 224–227 (2019).

    CAS  Google Scholar 

  9. Thompson, D. W. & Solomon, S. Interpretation of recent Southern Hemisphere climate change. Science 296, 895–899 (2002).

    CAS  Google Scholar 

  10. Son, S. W. et al. The impact of stratospheric ozone recovery on the Southern Hemisphere westerly jet. Science 320, 1486–1489 (2008).

    CAS  Google Scholar 

  11. Polvani, L. M., Waugh, D. W., Correa, G. J. & Son, S. W. Stratospheric ozone depletion: the main driver of twentieth-century atmospheric circulation changes in the Southern Hemisphere. J. Clim. 24, 795–812 (2011).

    Google Scholar 

  12. Eyring, V. et al. Long-term ozone changes and associated climate impacts in CMIP5 simulations. J. Geophys. Res. Atmos. 118, 5029–5060 (2013).

    CAS  Google Scholar 

  13. Arblaster, J., Meehl, G. & Karoly, D. Future climate change in the Southern Hemisphere: competing effects of ozone and greenhouse gases. Geophys. Res. Lett. 38, L02701 (2011).

    Google Scholar 

  14. McLandress, C. et al. Separating the dynamical effects of climate change and ozone depletion. Part II: Southern Hemisphere troposphere. J. Clim. 24, 1850–1868 (2011).

    Google Scholar 

  15. Banerjee, A., Fyfe, J. C., Polvani, L. M., Waugh, D. & Chang, K. L. A pause in Southern Hemisphere circulation trends due to the Montreal Protocol. Nature 579, 544–548 (2020).

    CAS  Google Scholar 

  16. Myhre, G. et al. in IPCC Climate Change 2013: The Physical Science Basis (eds Stocker, T. F. et al.) (Cambridge Univ. Press, 2013).

  17. Checa-Garcia, R., Hegglin, M. I., Kinnison, D., Plummer, D. A. & Shine, K. P. Historical tropospheric and stratospheric ozone radiative forcing using the CMIP6 database. Geophys. Res. Lett. 45, 3264–3273 (2018).

    CAS  Google Scholar 

  18. Gregory, J. M. Vertical heat transports in the ocean and their effect on time-dependent climate change. Clim. Dyn. 16, 501–515 (2000).

    Google Scholar 

  19. Frölicher, T. L. et al. Dominance of the Southern Ocean in anthropogenic carbon and heat uptake in CMIP5 models. J. Clim. 28, 862–886 (2015).

    Google Scholar 

  20. Fyfe, J. C., Saenko, O. A., Zickfeld, K., Eby, M. & Weaver, A. J. The role of poleward-intensifying winds on Southern Ocean warming. J. Clim. 20, 5391–5400 (2007).

    Google Scholar 

  21. Liu, W., Lu, J., Xie, S.-P. & Fedorov, A. Southern Ocean heat uptake, redistribution, and storage in a warming climate: the role of meridional overturning circulation. J. Clim. 31, 4727–4743 (2018).

    Google Scholar 

  22. Waugh, D. W. et al. Response of Southern Ocean ventilation to changes in midlatitude westerly winds. J. Clim. 32, 5345–5361 (2019).

    Google Scholar 

  23. Li, Q., England, M. H., & McC. Hogg, A. Transient Response of the Southern Ocean to Idealized Wind and Thermal Forcing across Different Model Resolutions. J. Clim. 34, 5477–5496 (2021).

    Google Scholar 

  24. Gille, S. T. Warming of the Southern Ocean since the 1950s. Science 295, 1275–1277 (2002).

    CAS  Google Scholar 

  25. Durack, P. J., Gleckler, P. J., Landerer, F. W. & Taylor, K. E. Quantifying underestimates of long-term upper-ocean warming. Nat. Clim. Change 4, 999–1005 (2014).

    Google Scholar 

  26. Sigmond, M., Reader, M. C., Fyfe, J. C. & Gillett, N. P. Drivers of past and future Southern Ocean change: stratospheric ozone versus greenhouse gas impacts. Geophys. Res. Lett. 38, 601 (2011).

  27. Swart, N. C., Gille, S. T., Fyfe, J. C. & Gillett, N. P. Recent Southern Ocean warming and freshening driven by greenhouse gas emissions and ozone depletion. Nat. Geosci. 11, 836–841 (2018).

    CAS  Google Scholar 

  28. Li, S., Liu, W., Lyu, K. & Zhang, X. The effects of historical ozone changes on Southern Ocean heat uptake and storage. Clim. Dyn. 57, 2269–2285 (2021).

    Google Scholar 

  29. Ring, M. J. & Plumb, R. A. The Response of a Simplified GCM to Axisymmetric Forcings: Applicability of the Fluctuation–Dissipation Theorem. J. Atmos. Sci. 65, 3880–3898 (2008).

  30. Bitz, C. M. & Polvani, L. M. Antarctic climate response to stratospheric ozone depletion in a fine resolution ocean climate model. Geophys. Res. Lett. 39, L20705 (2012).

    Google Scholar 

  31. Hegglin, M., Kinnison, D., Lamarque, J.-F. & Plummer, D. CCMI ozone in support of CMIP6 — version 1.0. Version 20160711. Earth System Grid Federation. https://doi.org/10.22033/ESGF/input4MIPs.1115 (2016).

    Article  Google Scholar 

  32. Eyring, V. et al. Overview of the Coupled Model Intercomparison Project Phase 6 (CMIP6) experimental design and organization. Geosci. Model Dev. 9, 1937–1958 (2016).

    Google Scholar 

  33. Seidel, D. J., Gillett, N. P., Lanzante, J. R., Shine, K. P. & Thorne, P. W. Stratospheric temperature trends: our evolving understanding. Wiley Interdiscip. Rev. Clim. Change 2, 592–616 (2011).

    Google Scholar 

  34. Shi, J. R., Talley, L. D., Xie, S. P., Liu, W. & Gille, S. T. Effects of Buoyancy and Wind Forcing on Southern Ocean Climate Change. J. Clim. 33, 10003–10020 (2020).

    Google Scholar 

  35. Bindoff, N. L. & McDougall, T. J. Diagnosing climate change and ocean ventilation using hydrographic data. J. Phys. Oceanogr. 24, 1137–1152 (1994).

    Google Scholar 

  36. Lyu, K., Zhang, X., Church, J. A. & Wu, Q. Processes responsible for the Southern Hemisphere ocean heat uptake and redistribution under anthropogenic warming. J. Clim. 33, 3787–3807 (2020).

    Google Scholar 

  37. Zhang, L. & Cooke, W. Simulated changes of the Southern Ocean air–sea heat flux feedback in a warmer climate. Clim. Dyn. 56, 1–16 (2021).

    Google Scholar 

  38. Sallée, J. B. et al. Assessment of Southern Ocean water mass circulation and characteristics in CMIP5 models: Historical bias and forcing response. J. Geophys. Res. Oceans 118, 1830–1844 (2013).

    Google Scholar 

  39. Cai, W., Cowan, T., Godfrey, S. & Wijffels, S. Simulations of processes associated with the fast warming rate of the southern midlatitude ocean. J. Clim. 23, 197–206 (2010).

    Google Scholar 

  40. Solomon, A., Polvani, L. M., Smith, K. L. & Abernathey, R. P. The impact of ozone depleting substances on the circulation, temperature, and salinity of the Southern Ocean: An attribution study with CESM1(WACCM). Geophys. Res. Lett. 42, 5547–5555 (2015).

    Google Scholar 

  41. Cheng, L. et al. Improved estimates of ocean heat content from 1960 to 2015. Sci. Adv. 3, e1601545 (2017).

    Google Scholar 

  42. Meehl, G. A. et al. Climate change projections in CESM1 (CAM5) compared to CCSM4. J. Clim. 26, 6287–6308 (2013).

    Google Scholar 

  43. Meehl, G. A. et al. Context for interpreting equilibrium climate sensitivity and transient climate response from the CMIP6 Earth system models. Sci. Adv. 6, eaba1981 (2020).

    Google Scholar 

  44. Nijsse, F. J., Cox, P. M. & Williamson, M. S. Emergent constraints on transient climate response (TCR) and equilibrium climate sensitivity (ECS) from historical warming in CMIP5 and CMIP6 models. Earth Syst. Dyn. 11, 737–750 (2020).

    Google Scholar 

  45. Xia, Y., Huang, Y. & Hu, Y. On the climate impacts of upper tropospheric and lower stratospheric ozone. J. Geophys. Res. Atmos. 123, 730–739 (2018).

    CAS  Google Scholar 

  46. Gillett, N. P. et al. The Detection and Attribution Model Intercomparison Project (DAMIP v1.0) contribution to CMIP6. Geosci. Model Dev. 9, 3685–3697 (2016).

    Google Scholar 

  47. Mindlin, J., Shepherd, T. G., Vera, C. & Osman, M. Combined effects of global warming and ozone depletion recovery on Southern Hemisphere atmospheric circulation and regional precipitation. Geophys. Res. Lett. 48, e2021GL092568 (2021).

    CAS  Google Scholar 

  48. Young, P. J. et al. Pre-industrial to end 21st century projections of tropospheric ozone from the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP). Atmos. Chem. Phys. 13, 2063–2090 (2013).

    Google Scholar 

  49. Swart, N. C. et al. The Canadian Earth System Model version 5 (CanESM5.0.3). Geosci. Model Dev. 12, 4823–4873 (2019).

    CAS  Google Scholar 

  50. NCAR Command Language v.6.5.0 (UCAR/NCAR/CISL/TDD, 2018); https://doi.org/10.5065/D6WD3XH5

  51. Liu, W. et al. Stratospheric ozone depletion and tropospheric ozone increases drive Southern Ocean interior warming. Zenodo https://doi.org/10.5281/zenodo.6003088 (2022).

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Acknowledgements

W.L. is supported by the Alfred P. Sloan Foundation as a research fellow and by the US National Science Foundation (AGS-2053121, OCE 2123422). K.L. and X.Z. are funded by the Centre for Southern Hemisphere Oceans Research (CSHOR), jointly funded by the Qingdao National Laboratory for Marine Science and Technology (QNLM, China) and the Commonwealth Scientific and Industrial Research Organisation (CSIRO, Australia).

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Authors and Affiliations

Authors

Contributions

W.L. conceived the study, performed the analysis and wrote the original draft of the manuscript. S.L. contributed to the analysis. W.L., M.I.H., R.C-G., S.L., N.P.G., K.L., X.Z. and N.C.S. contributed to interpreting the results and made substantial improvements to the manuscript.

Corresponding author

Correspondence to Wei Liu.

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The authors declare no competing interests.

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Nature Climate Change thanks William Seviour, Yan Xia and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Extended data

Extended Data Fig. 1 Prescribed ozone changes in CMIP5 and CMIP6 models.

Annual and zonal mean fractional change in ozone forcing (shading in fraction) between 1995–1999 and 1955–1959 (relative to 1955–1959) in the CMIP512,45 and most CMIP632 models (including CanESM5) used in the current study, that is, [O3(1995–1999) – O3(1955–1959)]/O3(1955–1959), in (a) CCSM4 and CESM1-CAM5, (b) GISS-E2-H, (c) FGOALS-g2 and (d) CMIP6 input4MIPs31.

Extended Data Fig. 2 Trends of Southern Hemisphere atmosphere temperature in CMIP5, CMIP6 and CanESM5 ozone experiments.

(top row) Trends of annual and zonal mean atmosphere temperature (shading in K/decade) during 1955–2000 for the multi-model means (MMMs) from (a) CMIP5 stratospheric and tropospheric ozone experiments and (b) CMIP6 stratospheric ozone-only experiments, and the ensemble means of (c) CanESM5 stratospheric and tropospheric ozone experiment and (d) CanESM5 stratosphere ozone-only experiment. The climatological annual and zonal mean atmosphere temperatures (contour in K, with an interval of 10 K) for the MMMs of CMIP5 and CMIP6 pre-industrial control runs are superimposed on panels (a) and (b), respectively. The annual climatology of zonal mean atmosphere temperature (contour in K, with an interval of 10 K) of CanESM5 pre-industrial control run is superimposed on panels (c) and (d), respectively. Stippling indicates that the trend is statistically insignificant at the 95% confidence level of the Mann-Kendall trend significance test (Methods).

Extended Data Fig. 3 Changes in Southern Hemisphere atmosphere temperature in CanESM5 ozone experiments.

(top row) Changes in annual and zonal mean atmosphere temperature (shading in K) during 1955–2000 (relative to pre-industrial control run) for the ensemble means of CanESM5 (a) stratospheric and tropospheric ozone experiment and (b) stratospheric ozone-only experiment as well as (c) the difference between the two indicating the effect of tropospheric ozone change. Stippling indicates that the change is statistically insignificant at the 95% confidence level of the Student’s t-test (Methods).

Extended Data Fig. 4 Changes in zonal mean surface heat fluxes over the Southern Ocean in CanESM5 ozone experiments.

(top row) Changes in annual and zonal mean net surface heat flux (shf, orange; significant, red), turbulent heat fluxes (sh+lh, light blue; significant, blue) and surface radiation fluxes (sw+lw, medium gray; significant, black) over the Southern Ocean during 1955–2000 (relative to pre-industrial control run) for the ensemble means in CanESM5 (a) stratospheric and tropospheric ozone experiment and (b) stratospheric ozone-only experiment as well as (c) the difference between the two indicating the effect of tropospheric ozone change. (bottom row) Same as the top row but for changes in annual and zonal mean surface sensible (sh, light blue; significant, blue) and latent (lh, orange; significant, red) heat fluxes and surface shortwave (sw, light green; significant, green) and longwave (lw, light purple; significant, purple) radiation fluxes. According to the data availability of CanESM5 simulations in the CMIP6 archives, the variable of net surface heat flux is obtained from ocean model outputs, which denotes the flux on the liquid ocean water surface. The variables of sensible and latent heat fluxes and shortwave and longwave radiation fluxes are obtained from atmosphere model outputs and land is then masked out for these variables so that the fluxes are on the liquid ocean water surface in most parts of the Southern Ocean and on sea ice surface around 60oS where sea ice exists. In all the panels, changes are tested based on the Student’s t-test and denoted statistically significant when exceeding the 95% confidence level (Methods).

Extended Data Fig. 5 Maps of surface heat flux changes over the Southern Ocean in CanESM5 ozone experiments.

(top row) Changes in annual mean (a) net surface heat flux (shf), (b) turbulent heat fluxes (sh + lh) and (c) surface radiation fluxes (sw + lw) (shading in W/m2) over the Southern Ocean during 1955–2000 (relative to pre-industrial control run) for the ensemble means in CanESM5 stratospheric and tropospheric ozone experiment. In panels (b) and (c), Antarctic sea ice extent (where sea ice concentration is at least 15% in pre-industrial control run) is masked out. (middle row) Same as the top row but for CanESM5 stratospheric ozone-only experiment. (bottom row) The difference between the top and middle rows indicating the effect of tropospheric ozone change.

Extended Data Fig. 6 Changes in zonal mean surface freshwater fluxes over the Southern Ocean in CanESM5 ozone experiments.

(top row) Changes in annual and zonal mean net surface freshwater flux (sfwf, orange; significant, red), precipitation minus evaporation (P-E, light blue; significant, blue) and freshwater fluxes due to other factors such as runoff, sea ice melt and brine rejection (other, medium gray; significant, black) over the Southern Ocean during 1955–2000 (relative to pre-industrial control run) for the ensemble means in CanESM5 (a) stratospheric and tropospheric ozone experiment and (b) stratospheric ozone-only experiment as well as (c) the difference between the two indicating the effect of tropospheric ozone change. (bottom row) Same as the top row but for changes in annual and zonal mean precipitation (light blue; significant, blue) and evaporation (orange; significant, red). According to the data availability of CanESM5 simulations in the CMIP6 archives, the variable of net surface freshwater flux is obtained from ocean model outputs, which denotes the flux on the liquid ocean water surface. The variables of precipitation and evaporation are obtained from atmosphere model outputs and land is then masked out for these variables so that the fluxes are on the liquid ocean water surface in most parts of the Southern Ocean and on sea ice surface around 60oS where sea ice exists. The freshwater fluxes due to other factors are calculated as the residual part, that is, sfwf minus (P-E). In all the panels, the changes are tested based on the Student’s t-test and denoted statistically significant when exceeding the 95% confidence level (Methods).

Extended Data Fig. 7 Maps of surface freshwater flux changes over the Southern Ocean in CanESM5 ozone experiments.

Same as Extended Data Fig. 5 but for changes in the net surface freshwater flux, precipitation minus evaporation and freshwater fluxes due to other factors (shading in 10−6 kg/s/m2).

Extended Data Fig. 8 Observed and simulated Southern Ocean interior warming.

Trends of zonal mean ocean temperature during 1955–2000 (shading in K/decade) in the upper 2000 m of the Southern Ocean from (a) the IAP data and (b) the ensemble mean of CanESM5 historical simulation. Stippling indicates that the trend is statistically insignificant at the 95% confidence level of the Mann-Kendall trend significance test (Methods).

Extended Data Fig. 9 Surface winds and wind stress curl changes over the Southern Ocean in CanESM5 ozone experiments.

Changes in annual mean surface winds (vector in m/s) and surface zonal winds (shading in m/s) over the Southern Ocean during 1955–2000 (relative to pre-industrial control run) for the ensemble means of CanESM5 (a) stratospheric and tropospheric ozone experiment and (b) stratospheric ozone-only experiment as well as (c) the difference between the two indicating the effect of tropospheric ozone change. (d) Changes in the zonal mean surface wind stress curl over the Southern Ocean due to total (blue), stratospheric (red) and tropospheric (black) ozone changes during 1955–2000. According to the data availability of CanESM5 simulations in the CMIP6 archives, the variables of surface zonal and meridional wind stress and winds are obtained from atmosphere model outputs and land is then masked out for the variables so that wind stress and winds are on the liquid ocean water surface in most parts of the Southern Ocean but on sea ice surface around or south of 60oS where sea ice exists. In panels (a)-(c), climatological annual mean Antarctic sea ice extent in pre-industrial control run is illustrated by the green contour of 15% sea ice concentration.

Extended Data Fig. 10 Surface zonal wind stress changes in CMIP5, CMIP6 and CanESM5 ozone experiments.

(a) Changes in annual and zonal mean surface zonal wind stress during 1955–2000 (relative to pre-industrial control run) for the ensemble means in CMIP5 and CanESM5 stratospheric and tropospheric ozone experiments. Except an outlier, GISS-E2-H, the other three CMIP5 models (CCSM4, CESM1-CAM5 and FGOALS-g2) show surface zonal wind stress changes consistent with CanESM5 under stratospheric and tropospheric ozone forcing. (b) Changes in annual and zonal mean surface zonal wind stress during 1955–2000 (relative to pre-industrial control run) for the ensemble means in CMIP6 stratospheric ozone-only experiments. The other three CMIP6 models (GISS-E2-1-G, IPSL-CM6A-LR and MIROC6) show surface zonal wind stress changes consistent with CanESM5 under stratospheric ozone-only forcing. (c) Same as (a) but without GISS-E2-H in which surface zonal wind stress changes of the three CMIP5 models are shown as MMM (blue) and inter-model spread (light blue). (d) Same as (b) in which surface zonal wind stress changes of the four CMIP6 models are shown as MMM (red) and inter-model spread (light red). CanESM5 results in panels (a) and (b) are superposed in panels (c) and (d), respectively. According to the data availability in the CMIP5 and CMIP6 archives, the variable of surface zonal wind stress is obtained from atmosphere model outputs and land is then masked out for the variable so that wind stress is on the liquid ocean water surface in most parts of the Southern Ocean but on sea ice surface around or south of 60oS where sea ice exists.

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Liu, W., Hegglin, M.I., Checa-Garcia, R. et al. Stratospheric ozone depletion and tropospheric ozone increases drive Southern Ocean interior warming. Nat. Clim. Chang. 12, 365–372 (2022). https://doi.org/10.1038/s41558-022-01320-w

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