ACPD Atmospheric Chemistry and Physics Discussions ACPD 1680-7375 Copernicus GmbH Göttingen, Germany 10.5194/acpd-10-19005-2010 Evidence for the effectiveness of the Montreal Protocol to protect the ozone layer Mäder J. A. 1 Staehelin J. 1 Peter T. 1 Brunner D. 1 3 Rieder H. E. 1 Stahel W. A. 2 Institute for Atmospheric and Climate Science, ETH Zurich, 8092 Zurich, Switzerland Seminar for Statistics, ETH Zurich, 8092 Zurich, Switzerland now at: EMPA – Material Science and Technology, Duebendorf, Switzerland 11 08 2010 10 8 19005 19029 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-discuss.net/10/19005/2010/acpd-10-19005-2010.html The full text article is available as a PDF file from http://www.atmos-chem-phys-discuss.net/10/19005/2010/acpd-10-19005-2010.pdf

The release of man-made ozone depleting substances (ODS, including chlorofluorocarbons and halons) into the atmosphere has lead to a near-linear increase in stratospheric halogen loading since the early 1970s, which started to level off after the mid-1990s and then to decline, in response to the ban of many ODSs by the Montreal Protocol (1987). We developed a multiple linear regression model to test whether this has already a measurable effect on total ozone values observed by the global network of ground-based instruments. The model includes explanatory variables describing the influence of various modes of dynamical variability and of volcanic eruptions. In order to describe the anthropogenic influence a first version of the model contains a linear trend (LT) term, whereas a second version contains a term describing the evolution of equivalent effective stratospheric chlorine (EESC). By comparing the explained variance of these two models we evaluated which of the two terms better describes the observed ozone evolution. For a significant majority of the stations, the EESC proxy fits the long term ozone evolution better than the linear trend term. Therefore, we conclude that the Montreal Protocol has started to show measurable effects on the ozone layer about twenty years after it became legally binding.

 References Appenzeller,~C., Weiss,~A K., and Staehelin,~J.: North Atlantic oscillation modulates total ozone winter trends, Geophys. Res. Lett., 27, 1131–1134, 2000. Austin,~J. and Wilson,~R J.: Ensemble simulations of the decline and recovery of stratospheric ozone, J. Geophys. Res.-Atmos., 111, D16314, \doi10.1029/2005jd006907, 2006. Brönnimann,~S. and Hood,~L L.: Frequency of low-ozone events over Northwestern Europe in 1952–1963 and 1990–2000, Geophys. Res. Lett., 30, ASC8-1-5, \doi10.1029/2003gl018431, 2003. Brunner, D., Staehelin, J., Maeder, J. A., Wohltmann, I., and Bodeker, G. E.: Variability and trends in total and vertically resolved stratospheric ozone based on the CATO ozone data set, Atmos. Chem. Phys., 6, 4985–5008, doi:10.5194/acp-6-4985-2006, 2006. Butchart,~N., Scaife,~A A., Bourqui,~M., de Grandpre,~J., Hare,~S H E., Kettleborough,~J., Langematz,~U., Manzini,~E., Sassi,~F., Shibata,~K., Shindell,~D., and Sigmond,~M.: Simulations of antropogenic change in the strength of the Brewer-Dobson circulation, Clim. Dynam., 27, 727–741, \doi10.1007/s00382-006-0162-4, 2006. Butchart,~N. and Scaife,~A A.: Removal of chlorofluorocarbons by increased mass exchange between the stratosphere and troposphere in a~changing climate, Nature, 410, 799–802, 2001. Cressie,~N A C.: Statistics for Spatial Data, revised edition, Wiley, New York, 1993. Cressie,~N. and Hawkins,~D M.: Robust estimation of the variogram, Int. Assoc. Math. Geol., 12, 115–125, 1980. Dameris,~M., Matthes,~S., Deckert,~R. Grewe,~V., and Ponater,~M.: Solar cycle effect delays onset of ozone recovery, Geophys. Res. Lett., 33, L03806, \doi10.1029/2005GL02474, 2006. Engel,~A., Strunk,~M., Muller,~M., Haase,~H P., Poss,~C., Levin,~I., and Schmidt,~U.: Temporal development of total chlorine in the high-latitude stratosphere based on reference distributions of mean age derived from \chemCO_2 and \chemSF_6,~J. Geophys. Res., 107(D12), 4136, doi:10.1029/2001JD000584, 2002. Eyring,~V., Waugh,~D W., Bodeker,~G E., Cordero,~E., Akiyoshi,~H., Austin,~J. Beagley,~S R., Boville,~B., Braesicke,~P., Brühl,~C., Butchart,~N., Chipperfield,~M P., Dameris,~M., Deckert,~R., Deushi,~M., Frith,~S M., Garcia,~R R., Gettelman,~A., Giorgetta,~M., Kinnison,~D E., Mancini,~E., Manzini,~E., Marsh~D R., Matthes,~S., Nagashima,~T., Newman,~P A., Nielsen,~J E., Pawson,~S., Pitari,~G., Plummer,~D A., Rozanov,~E., Schraner,~M., Scinocca,~J F., Semeniuk,~K., Shepherd,~T G., Shibata,~K., Steil,~B., Stolarski,~R., Tian,~W., and Yoshiki,~M.: Multimodel projections of stratospheric ozone in the 21st century,~J. Geophys. Res., 112, D16303, \doi10.1029/2006JD008332, 2007. Farman,~J B., Gardiner,~B G., and Shanklin,~J D.: Large losses of total ozone in Antarctica reveal seasonal, Nature, 315, 207–210, 1985. Fioletov,~V E., Labow,~G., Evans,~R., Hare,~E W., Kohler,~U., McElroy,~C T., Miyagawa,~K., Redondas,~A., Savastiouk,~V., Shalamyansky,~A M., Staehelin,~J., Vanicek,~K., and Weber,~M.: Performance of ground-based total ozone network assessed using satellite data,~J. Geophys. Res., 113, D14313, \doi10.1029/2008JD009809, 2008. Guillas,~S., Stein,~M L., Wuebbles,~D J., and Xia,~J.: Using chemistry transport modeling in statistical analysis of stratospheric ozone trends from observations,~J. Geophys. Res., 109, D22303, doi:10.1029/2004JD005049, 2004. Hadjinicolaou,~P., Pyle,~J., Chipperfield,~M P., and Kettleborough,~J., Effect of interannual meteorological variability on middle latitude \chemO_3, Geophys. Res. Lett., 24, 2993–2996, 1997. Hadjinicolaou,~P., Jrrar,~A., Pyle,~J., and Bishop,~L., The dynamically driven long-term trend in stratospheric ozone over northern middle latitudes,~Q J Roy. Meteorol. Soc., 128, 1393–1412, 2002. Harris, N. R. P., Kyrö, E., Staehelin, J., Brunner, D., Andersen, S.-B., Godin-Beekmann, S., Dhomse, S., Hadjinicolaou, P., Hansen, G., Isaksen, I., Jrrar, A., Karpetchko, A., Kivi, R., Knudsen, B., Krizan, P., Lastovicka, J., Maeder, J., Orsolini, Y., Pyle, J. A., Rex, M., Vanicek, K., Weber, M., Wohltmann, I., Zanis, P., and Zerefos, C.: Ozone trends at northern mid- and high latitudes – a European perspective, Ann. Geophys., 26, 1207–1220, doi:10.5194/angeo-26-1207-2008, 2008. Hegglin,~M I. and Shepherd,~T G.: Large climate-induced changes in UV index and stratosphere-to-troposphere ozone flux, Nat. Geosci., 2, 687–691, 2009. Hood,~L L. and Zaff,~D A.: Lower stratospheric stationary waves and the longitude dependence of ozone trends in winter, J. Geophys. Res.-Atmos., 100, 25791–25800, 1995. Hood,~L L. and Soukharev,~B E.: Interannual variations of total ozone at northern midlatitudes correlated with stratospheric EP flux and potential vorticity,~J. Atmos. Sci., 62, 3724–3740, 2005. Krizan,~P., and Lastovicka,~J.: Trends in positive and negative ozone laminae in the Northern Hemisphere,~J. Geophys. Research, 110, D10107, \doi10.1029/20004JD005477, 2005. Labitzke,~K. and Van Loon,~H.: The Stratosphere, Springer, 179~pp., 1999. Li, F., Stolarski, R. S., and Newman, P. A.: Stratospheric ozone in the post-CFC era, Atmos. Chem. Phys., 9, 2207–2213, doi:10.5194/acp-9-2207-2009, 2009. Mäder,~J A., Staehelin,~J., Brunner,~D., Stahel,~W A., Wohltmann,~I., and Peter,~T.: Statistical modeling of total ozone: Selection of appropriate explanatory variables,~J. Geophys. Res, 112, D11108, \doi10.1029/2006JD007694, 2007. McLandress,~C. and Shepherd,~T G.: Simulated anthropogenic changes in the Brewer-Dobson circulation, including its extension to higher latitudes, J. Clim., 22, 1516–1540, 2009. Molina,~M J. and Rowland,~F S.: Stratospheric sink for chlorofluoromethanes: chlorine atom-catalysed destruction of ozone, Nature, 249, 810–812, 1974. Montzka,~S A., Butler,~J H., Myers,~R C., Thompson,~T M., Swanson,~T H., Clarke,~A D., Lock,~L T., and Elkins,~J W.: Decline in tropospheric abundance of halogen from halocarbons: Implications for stratospheric ozone depletion, Science, 272, 1318–1322, 1996. Newchurch,~M J., Yang,~E S., Cunnold,~D M., Reinsel,~G C., Zawodny,~J M., and Russell,~J M.: Evidence for slowdown in stratospheric ozone loss: first stage of ozone recovery,~J. Geophys. Res., 108, 4507, doi:10.1029/2003JD003471, 2003. Newman, P. A., Daniel, J. S., Waugh, D. W., and Nash, E. R.: A new formulation of equivalent effective stratospheric chlorine (EESC), Atmos. Chem. Phys., 7, 4537–4552, doi:10.5194/acp-7-4537-2007, 2007. Newman,~P A., Nash,~E R., Kawa,~S R., Montzka,~S A., and Schauffler,~S M.: When will the Antarctic ozone hohle recover?, Geophys. Res. Lett., 33, L12814, \doi10.1029/2005GL025232, 2006. Orsolini,~Y. and Doblas-Reyes,~F.: Ozone signatures of climate patterns over the Euro-Atlantic sector in the spring,~Q J Roy. Meteorol. Soc., 595, 3251–3263, 2003. Percival,~D B., and Rothrock,~D A : \qutEyeballing trends in climate time series: a~coautionary note,~J. Climate, 18, 886–891, 2005. Peter,~T.: Microphysics and heterogeneous chemistry of polar stratospheric clouds, Ann. Rev. Phys. Chem., 48, 785–822, 1997. Randel,~W., Wu,~F., Russell,~J., Waters,~J., and Froidevaux,~L.: Ozone and temperature-changes in the stratosphere following the eruption of Mount-Pinatubo,~J. Geophys. Res, 100, 16753–16764, 1995. Reinsel,~G C., Miller,~A J., Weatherhead,~E C., Flynn,~L E., Nagatani,~R M., Tiao,~G C., and Wuebbles,~D J.: Trend analysis of total ozone data for turnaround and dynamical contributions,~J. Geophys. Res., 110, D16306, doi:10.1029/2004JD004662, 2005. Reinsel,~G C., Weatherhead,~E C., Tiao,~G C., Miller,~A J., Nagatani,~R M., Wuebbles,~D J., and Flynn,~L E.: On detection of turnaround and recovery in trend for ozone,~J. Geophys. Res., 107, 4078, doi:10.1029/2001JD000500, 2002. Rieder, H. E., Staehelin, J., Maeder, J. A., Peter, T., Ribatet, M., Davison, A. C., Stübi, R., Weihs, P., and Holawe, F.: Extreme events in total ozone over Arosa – Part 2: Fingerprints of atmospheric dynamics and chemistry and effects on mean values and long-term changes, Atmos. Chem. Phys. Discuss., 10, 12795–12826, doi:10.5194/acpd-10-12795-2010, 2010. Rinsland,~C P., Mahieu,~E., Zander,~R., Jones,~N B., Chipperfield,~M P., Goldman,~A., Anderson,~J., Russell,~J M., III, Demoulin,~P., Notholt,~J., Toon,~G C., Blavier,~J.-F., Sen,~B., Sussmann,~R., Wood,~S W., Meier,~A., Griffith,~D W T., Chiou,~L S., Murcray~F J., Stephen,~T M., Hase,~F., Mikuteit,~S., Schulz,~A., and Blumenstock,~T.: Long-term trends of inorganic chlorine from ground-based infrared solar spectra: past increases and evidence for stabilization,~J. Geophys. Res., 108, 4252, doi:10.1029/2002JD003001, 2003. Robock,~A.: Volcanic eruptions and climate, Rev. Geophys., 38, 191–219, 2000. Robock,~A., Adams,~T., Moore,~M., Oman,~L., and Stenchikov,~G.: Southern Hemisphere atmospheric circulation effects on th 1991 Mount Pinatubo Eruption, Geophys. Res. Lett., 34, L23710, \doi10.1029/2007GL031403, 2007. Rosenfield,~J E., Considine,~D B., Meade,~P E., Bacmeister,~J T., Jackman,~C H., and Schoeberl,~M R., Stratospheric effects of Mount Pinatubo aerosol studied with a~coupled two-dimensional model,~J. Geophys. Res., 102(D3), 3649–3670, 1997. Shepherd,~T G.: Dynamics, stratospheric ozone, and climate change, Atmos.-Ocean, 46, 371–392, 2008. Solomon,~S.: Stratospheric ozone depletion: a~review of concepts and history, Rev. Geophys., 37, 275–316, 1999. Solomon,~S., Portmann,~R W., and Thompsom,~D W J.: Contrasts between Antarctic and arctic ozone depletion, P. Natl. Acad. Sci. USA, 104, 445–449, 2007. Staehelin,~J., Harris,~N R P., Appenzeller,~C., and Eberhard,~J.: Ozone trends: A~review, Rev. Geophys., 39, 231–290, 2001. Staehelin,~J., Mäder,~J., Weiss,~A K., and Appenzeller,~C.: Long-term ozone trends in Northern mid-latitudes with special emphasis on contribution of changes in dynamics, Phys. Chem. Earth B, 27, 461–469, 2002. Steinbrecht,~W., Claude,~H., Kohler,~U., and Hoinka,~K P.: Correlations between tropopause height and total ozone: Implications for long-term changes, J. Geophys. Res.-Atmos., 103(D15), 19183–19192, 1998. Steinbrecht,~W., Claude,~H., and Winkler,~P.: Enhanced upper stratospheric ozone: Sign of recovery or solar cycle effect?,~J. Geophys. Res., 109, D02308, doi:10.1029/2003JD004284, 2004. Stolarski,~R S. and Cicerone,~R J.: Stratospheric chlorine: a~possible sink for ozone, Can J. Chem., 52, 1610–1615, 1974. Thompson,~D W J. and Wallace,~J M.: Annular modes in the extratropical circulation. Part I: Month-to-month variability, J. Climate, 13, 1000–1016, 2000. Waugh,~D W.,~L. Oman,~S R. Kawa,~R S. Stolarski,~S. Pawson,~A R. Douglass,~P A. Newman, and Nielsen,~J E.: Impacts of climate change on stratospheric ozone recovery, Geophys. Res. Lett., 36(3), L03805, \doi10.1029/2008GL036223, 2009. Weatherhead,~C. and Anderson,~S B.: The search for signs of recovery of the ozone layer, Nature, 441, 39–45, \doi10.1038/nature04746, 2006. Weatherhead,~E C., Reinsel,~G C., Tiao,~G C., Jackman,~C H., Bishop,~L., Frith S M H., DeLuisi J., Keller,~T., Oltmans,~S J., Fleming,~E L., Wuebbles,~D J., Kerr,~J B., Miller,~A J., Herman,~J., McPeters,~R., Nagatani,~R M., and Frederick,~J E.: Detecting the recovery of total column ozone,~J. Geophys. Res., 105, 22201–22210, 2000. Wohltmann,~I., Rex,~M., Brunner,~D., and Mäder,~J.: Integreated equivalent latitude as a~proxy for dynamical changes in ozone column, Geophys. Res. Lett., 32, L09811, doi:10.1029/2005GL022497, 2005. World Meteorological Organisation, Report of the International Ozone Trends Panel 1988, Rep. 18, Global Ozone Research and Monitoring Project, Geneva, 1989. World Meteorological Organisation. WMO Antarctic ozone bulletin 7, available at: http://www.wmo.ch/pages/prog/arep/gawozobull06_en.html, 2006. World Meteorological Organisation. Scientific Assessment of Ozone Depletion: 2006, Rep. 50, Global Ozone Research and Monitoring Project, Geneva, 2007. Yang,~E S., Cunnold,~D M., Newchurch,~M J., and Salawitch,~R J.: Change in ozone trends at southern high latitudes, Geophys. Res. Lett., 32, L12812, \doi10.1029/2004GL02296, 2005. 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. Geophy. Res., 111, D17309, doi:10.1029/2005JD006371, 2006.