ACP Atmospheric Chemistry and Physics ACP 1680-7324 Copernicus GmbH Göttingen, Germany 10.5194/acp-10-8803-2010 Quantifying the contributions to stratospheric ozone changes from ozone depleting substances and greenhouse gases Plummer D. A. 1 Scinocca J. F. 1 Shepherd T. G. 2 Reader M. C. 1 Jonsson A. I. 2 Canadian Centre for Climate Modelling and Analysis, Environment Canada, Victoria, BC, Canada Department of Physics, University of Toronto, Toronto, Canada 20 09 2010 10 18 8803 8820 This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://www.atmos-chem-phys.net/10/8803/2010/acp-10-8803-2010.html The full text article is available as a PDF file from http://www.atmos-chem-phys.net/10/8803/2010/acp-10-8803-2010.pdf

A state-of-the-art chemistry climate model coupled to a three-dimensional ocean model is used to produce three experiments, all seamlessly covering the period 1950–2100, forced by different combinations of long-lived Greenhouse Gases (GHGs) and Ozone Depleting Substances (ODSs). The experiments are designed to quantify the separate effects of GHGs and ODSs on the evolution of ozone, as well as the extent to which these effects are independent of each other, by alternately holding one set of these two forcings constant in combination with a third experiment where both ODSs and GHGs vary. We estimate that up to the year 2000 the net decrease in the column amount of ozone above 20 hPa is approximately 75% of the decrease that can be attributed to ODSs due to the offsetting effects of cooling by increased CO<sub>2</sub>. Over the 21st century, as ODSs decrease, continued cooling from CO<sub>2</sub> is projected to account for more than 50% of the projected increase in ozone above 20 hPa. Changes in ozone below 20 hPa show a redistribution of ozone from tropical to extra-tropical latitudes with an increase in the Brewer-Dobson circulation. In addition to a latitudinal redistribution of ozone, we find that the globally averaged column amount of ozone below 20 hPa decreases over the 21st century, which significantly mitigates the effect of upper stratospheric cooling on total column ozone. Analysis by linear regression shows that the recovery of ozone from the effects of ODSs generally follows the decline in reactive chlorine and bromine levels, with the exception of the lower polar stratosphere where recovery of ozone in the second half of the 21st century is slower than would be indicated by the decline in reactive chlorine and bromine concentrations. These results also reveal the degree to which GHG-related effects mute the chemical effects of N<sub>2</sub>O on ozone in the standard future scenario used for the WMO Ozone Assessment. Increases in the residual circulation of the atmosphere and chemical effects from CO<sub>2</sub> cooling more than halve the increase in reactive nitrogen in the mid to upper stratosphere that results from the specified increase in N<sub>2</sub>O between 1950 and 2100.

 References Arora, V. K., Boer, G. J., Christian, J. R., Curry, C. L., Denman, K. L., Zahariev, K., Flato, G. M., Scinocca, J. F., Merryfield, W. J., and Lee, W. G.: The effect of terrestrial photosynthesis down regulation on the twentieth-century carbon budget simulated with the CCCma earth system model, J. Climate, 22, 6066–6088, 2009. Austin, J. and Wilson, R. J.: Ensemble simulations of the decline and recovery of stratospheric ozone, J. Geophys. Res., 111, D16314, doi:10.1029/2005JD006907, 2006. Austin, J., Wilson, J., Li, F., and Vömel, H.: Evolution of water vapor concentrations and stratospheric age of air in coupled chemistry-climate model simulations, J. Atmos. Sci., 64, 905–921, 2007. Brasseur, G. and Hitchman, M. H.: Stratospheric response to trace gas perturbations: Changes in ozone and temperature distributions, Science, 240, 634–637, 1988. Butchart, N., Scaife, A. A., Bourqui, M., de Grandpré, J., Hare, S. H. E., Kettleborough, J., Langematz, U., Manzini, E., Sassi, F., Shibata, K., Shindell, D., and Sigmond, M.: Simulations of anthropogenic change in the strength of the Brewer-Dobson circulation, Clim. Dynam., 27, 727–741, doi:10.1007s00382-006-0162-4, 2006. Butchart, N., Cionni, I., Eyring, V., Shepherd, T. G., Waugh, D. W., Akiyoshi, H., Austin, J., Brühl, C., Chipperfield, M. P., Cordero, E., Dameris, M., Deckert, R., Dhomse, S., Frith, S. M., Garcia, R. R., Gettelman, A., Giorgetta, M. A., Kinnison, D. E., Li, F., Mancini, E., McLandress, C., Pawson, S., Pitari, G., Plummer, D. A., Rozonov, E., Sassi, F., Scinocca, J. F., Shibata, K., Steil, B., and Tian, W.: Chemistry-climate model simulations of 21st century stratospheric climate and circulation changes, J. Climate, doi:10.1175/2010JCLI3404.1, in press, 2010. Chipperfield, M. P. and Feng, W.: Comment on: Stratospheric Ozone Depletion at northern mid-latitudes in the 21st century: The importance of future concentrations of greenhouse gases nitrous oxide and methane, Geophys. Res. Lett., 30, 1389, doi:10.1029/2002GL016353, 2003. de Grandpré, J., Sandilands, J. W., McConnell, J. C., Beagley, S. R., Croteau, P. C., and Danilin, M. Y.: Canadian Middle Atmosphere Model: Preliminary results from the chemical transport module, Atmos.-Ocean, 35, 385–431, 1997. Drdla, K., Gandrud, B. W., Baumgardner, D., Wilson, J. C., Bui, T. P., Hurst, D., Schauffler, S. M., Jost, H., Greenblatt, J. B., and Webster, C. R.: Evidence for the widespread presence of liquid-phase particles during the 1999–2000 Arctic winter, J. Geophys. Res., 107, 8318, doi:10.1029/2001JD001127, 2002. IPCC – Intergovernmental Panel on Climate Change: Special report on emissions scenarios: a special report of Working Group~III of the Intergovernmental Panel on Climate Change, Cambridge University Press, Cambridge, UK, 599~pp., 2000. Engel, A., Möbius, T., Bönisch, H., Schmidt, U., Heinz, R., Levin, I., Atlas, E., Aoki, S., Nakazawa, T., Sugawara, S., Moore, F., Hurst, D., Elkins, J., Schauffler, S., Andrews, A., and Boering, K.: Age of stratospheric air unchanged within uncertainties over the past 30 years, Nature Geosci., 2, 28–31, 2009. Eyring, V., Butchart, N., Waugh, D. W., et al.: Assessment of temperature, trace species, and ozone in chemistry-climate model simulations of the recent past, J. Geophys. Res., 111, D22308, doi:10.1029/2006JD007327, 2006. Eyring, V., Waugh, D. W., Bodeker, G. E., Cordero, E., et al.: Multimodel projections of stratospheric ozone in the 21st century, J. Geophys. Res., 112, D16303, doi:10.1029/2006JD008332, 2007. Eyring, V., Chipperfield, M. P., Giorgetta, M. A., Kinnison, D. E., Manzini, E., Matthes, K., Newman, P. A., Pawson, S., Shepherd, T. G., and Waugh, D. W.: Overview of the new CCMVal reference and sensitivity simulations in support of upcoming ozone and climate assessments and the planned SPARC CCMVal report, SPARC (Stratospheric processes and their role in climate) Newsletter, 30, 20–26, 2008. Eyring, V., Cionni, I., Bodeker, G. E., Charlton-Perez, A. J., Kinnison, D. E., Scinocca, J. F., Waugh D. W., et al.: Multi-model assessment of stratospheric ozone return dates and ozone recovery in CCMVal-2 models, Atmos. Chem. Phys. Discuss., 10, 11659–11710, doi:10.5194/acpd-10-11659-2010, 2010. Fomichev, V. I., Jonsson, A. I., de Grandpré, J., Beagley, S. R., McLandress, C., Semeniuk, K., and Shepherd, T. G.: Response of the middle atmosphere to CO<sub>2</sub> doubling: Results from the Canadian Middle Atmosphere Model, J. Climate, 20, 1121–1144, 2007. Gent, P. R., Bryan, F. O., Danabasoglu, G., Doney, S. C., Holland, W. R., Large, W. G., and McWilliams, J. C.: The NCAR Climate System Model global ocean component, J. Climate, 11, 1287–1306, 1998. Haigh, J. D. and Pyle, J. A.: Ozone perturbation in a two-dimensional circulation model, Q. J. Roy. Meteorol. Soc., 108, 551–574, 1982. Hegglin, M. I. and Shepherd, T. G.: O<sub>3</sub>-N<sub>2</sub>O correlations from the Atmospheric Chemistry Experiment: Revisiting a diagnostic of transport and chemistry in the stratosphere, J. Geophys. Res., 112, D19301, doi:10.1029/2006JD008281, 2007. Hegglin, M. I. and Shepherd, T. G.: Large climate-induced changes in ultraviolet index and stratosphere-to-troposphere ozone flux, Nat. Geosci., 2, 687–691, 2009. Holton, J. R., Haynes, P. H., McIntyre, M. E., Douglass, A. R., Rood, R. B., and Pfister, L.: Stratosphere-troposphere exchange, Rev. Geophys., 33, 403–439, 1995. Jonsson, A. I., de Grandpré, J., Fomichev, V. I., McConnell, J. C., and Beagley, S. R.: Doubled CO<sub>2</sub>-induced cooling in the middle atmosphere: Photochemical analysis of the ozone radiative feedback, J. Geophys. Res., 109, D24103, doi:10.1029/2004JD005093, 2004. Jonsson, A. I., Fomichev, V. I., and Shepherd, T. G.: The effect of nonlinearity in CO<sub>2</sub> heating rates on the attribution of stratospheric ozone and temperature changes, Atmos. Chem. Phys., 9, 8447–8452, doi:10.5194/acp-9-8447-2009, 2009. Li, F., Austin, J., and Wilson, J.: The strength of the Brewer-Dobson circulation in a changing climate: coupled chemistry-climate model simulations, J. Climate, 21, 40–57, 2008. McLandress, C. and Shepherd, T. G.: Simulated anthropogenic changes in the Brewer-Dobson circulation, including its extension to high latitudes, J. Climate, 22, 1516–1540, 2009. McLandress, C., Jonsson, A. I., Plummer, D. A., Reader, M. C., Scinocca, J. F., and Shepherd, T. G.: Separating the dynamical effects of climate change and ozone depletion: Part~1, Southern Hemisphere stratosphere, under revision, J. Climate, 2010. Montzka, S. A., Butler, J. H., Elkins, J. W., Thompson, T. M., Clarke, A. D., and Lock, L. T.: Present and future trends in the atmospheric burden of ozone-depleting halogens, Nature, 398, 690–694, 1999. Oman, L., Waugh, D. W., Pawson, S., Stolarski, R. S., and Nielsen, J. E.: Understanding the changes in stratospheric water vapor in coupled chemistry-climate model simulations, J. Atmos. Sci., 65, 3278–3291, 2008. Oman, L. D., Waugh, D. W., Kawa, S. R., Stolarski, R. S., Douglass, A. R., and Newman, P. A.: Mechanisms and feedback causing changes in upper stratospheric ozone in the 21st century, J. Geophys. Res., 115, D05303, doi:10.1029/2009JD012397, 2010. Portmann, R. W. and Solomon, S.: Indirect radiative forcing of the ozone layer during the 21st century, Geophys. Res. Lett., 34, L02813, doi:10.1029/2006GL028252, 2007. Randel, W. J. and Wu, F.: A stratospheric ozone profile data set for 1979–2005: Variability, trends, and comparisons with column ozone data, J. Geophys. Res., 112, D06313, doi:10.1029/2006JD007339, 2007. Randel, W. J., Shine, K. P., Austin, J., Barnett, J., Claud, C., Gillett, N. P., Keckhut, P., Langematz, U., Lin, R., Long, C., Mears, C., Miller, C., Nash, J., Seidel, D. J., Thompson, D. W. J., Wu, F., and Yoden, S.: An update of observed stratospheric temperature trends, J. Geophys. Res., 114, D02107, doi:10.1029/2008JD010421, 2009. Randeniya, L. K., Vohralik, P. F., and Plumb, I. C.: Stratospheric ozone depletion at northern mid-latitudes in the 21st century: The importance of future concentrations of greenhouse gases nitrous oxide and methane, Geophys. Res. Lett., 29, 1051, doi:10.1029/2001GL014295, 2002. Ravishankara, A. R., Daniel, J. S., and Portmann, R. W.: Nitrous oxide (N<sub>2</sub>O): The dominant ozone-depleting substance emitted in the 21st century, Science, 326, 123–125, 2009. Rosenfield, J. E. and Douglass, A. R.: Doubled CO<sub>2</sub> effects on NO<sub>y</sub> in a coupled 2D model, Geophys. Res. Lett., 25, 4381–4384, 1998. Rosenfield, J. E., Douglass, A. R., and Considine, D. B.: The impact of increasing carbon dioxide on ozone recovery, J. Geophys. Res., 107, 4049, doi:10.1029/2001JD000824, 2002. Rosenfield, J. E., Frith, S. M., and Stolarski, R. S.: Version~8~SBUV ozone profile trends compared with trends from a zonally averaged chemical model, J. Geophys. Res., 110, D12302, doi:10.1029/2004JD005466, 2005. Santer, B. D., Wigley, T. M. L., Boyle, J. S., Gaffen, D. J., Hnilo, J. J., Nychka, D., Parker, D. E., and Taylor, K. E.: Statistical significance of trends and trend differences in layer-average atmospheric temperature time series, J. Geophys. Res., 105, 7337–7356, 2000. Scinocca, J. F., McFarlane, N. A., Lazare, M., Li, J., and Plummer, D.: Technical Note: The CCCma third generation AGCM and its extension into the middle atmosphere, Atmos. Chem. Phys., 8, 7055–7074, doi:10.5194/acp-8-7055-2008, 2008. Shepherd, T. G.: Dynamics, stratospheric ozone and climate change, Atmos.-Ocean., 46, 117–138, 2008. Shepherd, T. G. and Jonsson, A. I.: On the attribution of stratospheric ozone and temperature changes to changes in ozone-depleting substances and well-mixed greenhouse gases, Atmos. Chem. Phys., 8, 1435–1444, doi:10.5194/acp-8-1435-2008, 2008. Shine, K. P., Bourqui, M. S., Forster, P. M. F., Hare, S. H. E., Langematz, U., Braesicke, P., Grewe, V., Ponater, M., Schnadt, C., Smith, C. A., Haigh, J. D., Austin, J., Butchart, N., Shindell, D. T., Randel, W. J., Nagashima, T., Portmann, R. W., Solomon, S., Seidel, D. J., Lanzante, J., Klein, S., Ramaswamy, V., and Schwarzkopf, M. D.: A comparison of model-simulated trends in stratospheric temperatures, Q. J. Roy. Meteorol. Soc., 129(590), 1565–1588, 2003. Son, S.-W., Polvani, L. M., Waugh, D. W., Birner, T., Akiyoshi, H., Garcia, R. R., Gettelman, A., Plummer, D. A., and Rozanov, E.: The impact of stratospheric ozone recovery on tropopause height trends, J. Climate, 22, 429–445, 2009. SPARC CCMVal: SPARC CCMVal Report on the Evaluation of Chemistry-Climate Models, edited by: Eyring, V., Shepherd, T. G., and Waugh, D. W., SPARC Report No 5, WCRP-132, WMO/TD-NO 1526., http://www.atmosp.physics.utoronto.ca/SPARC, 2010. Waugh, D. W. and Eyring, V.: Quantitative performance metrics for stratospheric-resolving chemistry-climate models, Atmos. Chem. Phys., 8, 5699–5713, doi:10.5194/acp-8-5699-2008, 2008. Waugh, D. W., Oman, L., Kawa, S. R., Stolarski, R. S., Pawson, S., Douglass, A. R., Newman, P. A., and Nielsen, J. E.: Impacts of climate change on stratospheric ozone recovery, Geophys. Res. Lett., 36, L03805, doi:10.1029/2008GL036223, 2009. World Meteorological Organization (WMO)/United Nations Environment Programme (UNEP): Scientific Assessment of Ozone Depletion: 2006, World Meteorological Organization, Global Ozone Research and Monitoring Project, Report No 50, Geneva, Switzerland, 2007. Yang, E.-S., Cunnold, D. M., Salawitch, R. J., McCormick, M. P., Russell~III, J., Zawodny, J. M., Oltmans, S., and Newchurch, M. J.: Attribution of recovery in lower-stratospheric ozone, J. Geophys. Res., 111, D17309, doi:10.1029/2005JD006371, 2006.