ACP Atmospheric Chemistry and Physics ACP Atmos. Chem. Phys. 1680-7324 Copernicus Publications Göttingen, Germany 10.5194/acp-13-2267-2013 Analysis of global methane changes after the 1991 Pinatubo volcanic eruption Bândă N. 1 2 Krol M. https://orcid.org/0000-0002-3506-2477 1 3 4 van Weele M. https://orcid.org/0000-0002-3191-5604 2 van Noije T. https://orcid.org/0000-0002-5148-5867 2 Röckmann T. https://orcid.org/0000-0002-6688-8968 1 Institute for Marine and Atmospheric Research Utrecht, Utrecht University, Utrecht, The Netherlands Royal Netherlands Meteorological Institute (KNMI), De Bilt, The Netherlands Dept. of Meteorology and Air Quality, Wageningen University and Research Center, Wageningen, The Netherlands Netherlands Institute for Space Research (SRON), Utrecht, The Netherlands 27 02 2013 13 4 2267 2281 Copyright: © 2013 N. Bândă et al. 2013 This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/ This article is available from https://acp.copernicus.org/articles/13/2267/2013/acp-13-2267-2013.html The full text article is available as a PDF file from https://acp.copernicus.org/articles/13/2267/2013/acp-13-2267-2013.pdf

The global methane (CH<sub>4</sub>) growth rate showed large variations after the eruption of Mount Pinatubo in June 1991. Both sources and sinks of tropospheric CH<sub>4</sub> were altered following the eruption, by feedback processes between climate and tropospheric photochemistry. Such processes include Ultra Violet (UV) radiative changes due to the presence of volcanic sulfur dioxide (SO<sub>2</sub>) and sulphate aerosols in the stratosphere, and due to stratospheric ozone depletion. Changes in temperature and water vapour in the following years caused changes in tropospheric chemistry, as well as in natural emissions. We present a sensitivity study that investigates the relative effects that these processes had on tropospheric CH<sub>4</sub> concentrations, using a simple one-dimensional chemistry model representative for the global tropospheric column. To infer the changes in UV radiative fluxes, the chemistry model is coupled to a radiative transfer model. We find that the overall effect of natural processes after the eruption on the CH<sub>4</sub> growth rate is dominated by the reduction in CH<sub>4</sub> lifetime due to stratospheric ozone depletion. However, all the other processes are found to have non-negligible effects, and should therefore be taken into account in order to obtain a good estimate of CH<sub>4</sub> concentrations after Pinatubo. We find that the overall effect was a small initial increase in the CH<sub>4</sub> growth rate after the eruption, followed by a decrease of about 7 ppb yr<sup>−1</sup> by mid-1993. When changes in anthropogenic emissions are employed according to emission inventories, an additional decrease of about 5 ppb yr<sup>−1</sup> in the CH<sub>4</sub> growth rate is obtained between the years 1991 and 1993. The results using the simplified single column model are in good qualitative agreement with observed changes in the CH<sub>4</sub> growth rate. Further analysis, taking into account changes in the dynamics of the atmosphere, variations in emissions from biomass burning, and in biogenic emissions of non-methane volatile organic compounds (NMVOC), requires the use of a full three-dimensional model.

 References Bekki, S. and Law, K.&nbsp;S.: Sensitivity of the atmospheric CH<sub>4</sub> growth rate to global temperature changes observed from 1980 to 1992, Tellus, 49B, 409–416, 1997. Bekki, S. and Pyle, J.&nbsp;A.: A two-dimensional modeling study of the volcanic eruption of Mount Pinatubo, J. Geophys. Res., 99, 18861–18869, 1994. Bekki, S., Law, K.&nbsp;S., and Pyle, J.&nbsp;A.: Effect of ozone depletion on atmospheric CH<sub>4</sub> and CO concentrations, Nature, 371, 595–597, 1994. Bender, F.&nbsp;A., Ekman, A. M.&nbsp;L., and Rodhe, H.: Response to the eruption of Mount Pinatubo in relation to climate sensitivity in the CMIP3 models, Clim. Dynam., 35, 875–886, <a href="http://dx.doi.org/10.1007/s00382-010-0777-3">https://doi.org/10.1007/s00382-010-0777-3</a>, 2010. Bousquet, P., Ciais, P., Miller, J.&nbsp;B., Dlugokencky, E.&nbsp;J., Hauglustaine, D.&nbsp;A., Prigent, C., Van der Werf, G.&nbsp;R., Peylin, P., Brunke, E.-G., Carouge, C., Langenfelds, R.&nbsp;L., Lathière, J., Papa, F., Ramonet, M., Schmidt, M., Steele, L.&nbsp;P., Tyler, S.&nbsp;C., and White, J.: Contribution of anthropogenic and natural sources to atmospheric methane variability, Nature, 443, 439–443, <a href="http://dx.doi.org/10.1038/nature05132">https://doi.org/10.1038/nature05132</a>, 2006. Butler, T. M., Simmonds, I., and Rayner, P. J.: Mass balance inverse modelling of methane in the 1990s using a Chemistry Transport Model, Atmos. Chem. Phys., 4, 2561–2580, <a href="http://dx.doi.org/10.5194/acp-4-2561-2004">https://doi.org/10.5194/acp-4-2561-2004</a>, 2004. Camp, C.&nbsp;D., Roulston, M.&nbsp;S., Haldemann, A.&nbsp;F., and Yung, Y.&nbsp;L.: The sensitivity of tropospheric methane to the interannual variability in stratospheric ozone, Chemosphere – Global Change Sci., 3, 147–156, <a href="http://dx.doi.org/10.1016/S1465-9972(00)00053-2">https://doi.org/10.1016/S1465-9972(00)00053-2</a>, 2001. Chipperfield, M.&nbsp;P., Randel, W.&nbsp;J., Bodeker, G.&nbsp;E., Dameris, M., Fioletov, V.&nbsp;E., Friedl, R.&nbsp;R., Harris, N. R.&nbsp;P., Logan, J.&nbsp;A., McPeters, R.&nbsp;D., Muthama, N.&nbsp;J., Peter, T., Shepherd, T.&nbsp;G., Shine, K.&nbsp;P., Solomon, S., Thomason, L.&nbsp;W., and Zawodny, J.&nbsp;M.: Global Ozone: Past and Future, in: Scientific Assessment of Ozone Depletion: 2002, Global Ozone Research and Monitoring Project, Report No. 47, chap.&nbsp;4, Geneva, 2003. Dee, D.&nbsp;P., Uppala, S.&nbsp;M., Simmons, A.&nbsp;J., Berrisford, P., Poli, P., Kobayashi, S., Andrae, U., Balmaseda, M.&nbsp;A., Balsamo, G., Bauer, P., Bechtold, P., Beljaars, A. C.&nbsp;M., Berg, L. V.&nbsp;D., Bidlot, J., Bormann, N., Delsol, C., Dragani, R., Fuentes, M., Geer, A.&nbsp;J., Haimberger, L., Healy, S.&nbsp;B., Hersbach, H., Holm, E.&nbsp;V., Isaksen, L., and Kallberg, P.: The ERA-Interim reanalysis : configuration and performance of the data assimilation system, Q. J. Roy. Meteorol. Soc., 137, 553–597, <a href="http://dx.doi.org/10.1002/qj.828">https://doi.org/10.1002/qj.828</a>, 2011. Dlugokencky, E.&nbsp;J., Masaire, K.&nbsp;A., Lang, P.&nbsp;M., Tans, P.&nbsp;P., Steele, L.&nbsp;P., and Nisbet, E.&nbsp;G.: A dramatic decrease in the growth rate of atmospheric methane in the northern hemisphere during 1992, Geophys. Res. Lett., 21, 45–48, 1994. Dlugokencky, E.&nbsp;J., Dutton, E.&nbsp;G., Novelli, P.&nbsp;C., Tans, P.&nbsp;P., Masarie, K.&nbsp;A., Lantz, K.&nbsp;O., and Madronich, S.: Changes in CH<sub>4</sub> and CO growth rates after the eruption of Mt. Pinatubo and their link with changes in tropical tropospheric UV flux, Geophys. Res. Lett., 23, 2761–2764, 1996. Dlugokencky, E.&nbsp;J., Houweling, S., Bruhwiler, L., Masarie, K.&nbsp;A., Lang, P.&nbsp;M., Miller, J.&nbsp;B., and Tans, P.&nbsp;P.: Atmospheric methane levels off: Temporary pause or a new steady- state?, Geophys. Res. Lett., 30, 1992, <a href="http://dx.doi.org/10.1029/2003GL018126">https://doi.org/10.1029/2003GL018126</a>, 2003. Dlugokencky, E.&nbsp;J., Nisbet, E.&nbsp;G., Fisher, R., and Lowry, D.: Global atmospheric methane: budget, changes and dangers, Phil. Trans. R. Soc. A, 369, 2058–2072, <a href="http://dx.doi.org/10.1098/rsta.2010.0341">https://doi.org/10.1098/rsta.2010.0341</a>, 2011. Dunfield, P., Knowles, R., Dumont, R., and Moore, T.&nbsp;R.: Methane production and consumption in temperate and subarctic peat soils: Response to temperature and pH, Soil Biol. Biochem., 25, 321–326, 1993. Elterman, L.: UV, Visible and IR Attenuation for Altitudes to 50 km, Environ. Res. Pap., 285, AFCRL-68-0153, 1968. Etheridge, D.&nbsp;M., Steele, L.&nbsp;P., Francey, R.&nbsp;J., and Langenfelds, R.&nbsp;L.: Atmospheric methane between 1000 A. D. and present: Evidence of anthropogenic emissions and climatic variability, J. Geophys. Res., 103, 15979–15993, 1998. European Commission and Joint Research Centre (JRC)/Netherlands Environmental Assessment Agency (PBL)}: {Emission Database for Global Atmospheric Research (EDGAR), release version 4.1, available at: <a href="http://edgar.jrc.ec.europa.eu/">http://edgar.jrc.ec.europa.eu/</a> (last access: 17 November 2011), 2010. Free, M. and Angell, J.&nbsp;K.: Effect of volcanoes on the vertical temperature profile in radiosonde data, J. Geophys. Res., 107, 4101, <a href="http://dx.doi.org/10.1029/2001JD001128">https://doi.org/10.1029/2001JD001128</a>, 2002. Fuglestvedt, J.&nbsp;S., Johnson, J.&nbsp;E., and Isaksen, I. S.&nbsp;A.: Effects of reductions in stratospheric ozone on tropospheric chemistry through changes in photolysis rates, Tellus, 46B, 172–192, 1994. Gauci, V., Blake, S., Stevenson, D.&nbsp;S., and Highwood, E.&nbsp;J.: Halving of the northern wetland CH<sub>4</sub> source by a large Icelandic volcanic eruption, J. Geophys. Res., 113, 1–8, <a href="http://dx.doi.org/10.1029/2007JG000499">https://doi.org/10.1029/2007JG000499</a>, 2008. Gettelman, A., Hoor, P., Pan, L.&nbsp;L., Randel, W.&nbsp;J., Hegglin, M.&nbsp;I., and Birner, T.: The extratropical upper troposphere and lower stratosphere, Rev. Geophys., 49, RG3003, <a href="http://dx.doi.org/10.1029/2011RG000355">https://doi.org/10.1029/2011RG000355</a>, 2011. GLOBALVIEW-CH4: Cooperative Atmospheric Data Integration Project – Methane. CD-ROM, NOAA ESRL, Boulder, Colorado, also available on Internet via anonymous FTP to <a href="ftp://ftp.cmdl.noaa.gov, Path: ccg/ch4/GLOBALVIEW">ftp://ftp.cmdl.noaa.gov, Path: ccg/ch4/GLOBALVIEW</a> (last access: 16 February 2012), 2009. Grant, A., Archibald, A.&nbsp;T., Cooke, M.&nbsp;C., and Shallcross, D.&nbsp;E.: Modelling the oxidation of seventeen volatile organic compounds to track yields of CO and CO<sub>2</sub>, Atmos. Environ., 44, 3797–3804, <a href="http://dx.doi.org/10.1016/j.atmosenv.2010.06.049">https://doi.org/10.1016/j.atmosenv.2010.06.049</a>, 2010. Guenther, A.&nbsp;B., Zimmerman, P.&nbsp;R., Harley, P.&nbsp;C., Monson, R.&nbsp;K., and Fall, R.: Isoprene and Monoterpene Emission Rate Variability: Model Evaluations and Sensitivity Analyses, J. Geophys. Res., 98, 12609–12617, 1993. Guo, S., Bluth, G. J.&nbsp;S., Rose, W.&nbsp;I., Watson, I.&nbsp;M., and Prata, A.&nbsp;J.: Re-evaluation of SO2 release of the 15 June 1991 Pinatubo eruption using ultraviolet and infrared satellite sensors, Geochem. Geophys. Geosyst., 5, Q04001, <a href="http://dx.doi.org/10.1029/2003GC000654">https://doi.org/10.1029/2003GC000654</a>, 2004{a}. Guo, S., Rose, W.&nbsp;I., Bluth, G. J.&nbsp;S., and Watson, I.&nbsp;M.: Particles in the great Pinatubo volcanic cloud of June 1991: The role of ice, Geochem. Geophys. Geosyst., 5, Q05003, <a href="http://dx.doi.org/10.1029/2003GC000655">https://doi.org/10.1029/2003GC000655</a>, 2004{b}. Hansen, J., Sato, M., Ruedy, R., Nazarenko, L., Lacis, A., Schmidt, G.&nbsp;A., Russell, G., Aleinov, I., Bauer, M., Bell, N., Cairns, B., Canuto, V., Chandler, M., Cheng, Y., Del Genio, A., Faluvegi, G., Fleming, E., Friend, A., Hall, T., Jackman, C., Kelley, M., Kiang, N., Koch, D., Lean, J., Lerner, J., Lo, K., Menon, S., Miller, R., Minnis, P., Novakov, T., Oinas, V., Perlwitz, J., Perlwitz, J., Rind, D., Romanou, A., Shindell, D., Stone, P., Sun, S., Tausnev, N., Thresher, D., Wielicki, B., Wong, T., Yao, M., and Zhang, S.: Efficacy of climate forcings, J. Geophys. Res., 110, D18104, <a href="http://dx.doi.org/10.1029/2005JD005776">https://doi.org/10.1029/2005JD005776</a>, 2005. Hansen, J., Ruedy, R., Sato, M., and Lo, K.: Global surface temperature change, Rev. Geophys., 48, RG4004, <a href="http://dx.doi.org/10.1029/2010RG000345">https://doi.org/10.1029/2010RG000345</a>, 2010. Hodson, E.&nbsp;L., Poulter, B., Zimmermann, N.&nbsp;E., Prigent, C., and Kaplan, J.&nbsp;O.: The El Niño Southern Oscillation and wetland methane interannual variability, Geophys. Res. Lett., 38, 3–6, <a href="http://dx.doi.org/10.1029/2011GL046861">https://doi.org/10.1029/2011GL046861</a>, 2011. Huijnen, V., Williams, J., van Weele, M., van Noije, T., Krol, M., Dentener, F., Segers, A., Houweling, S., Peters, W., de&nbsp;Laat, J., Boersma, F., Bergamaschi, P., van Velthoven, P., Le Sager, P., Eskes, H., Alkemade, F., Scheele, R., Nédélec, P., and Pätz, H.-W.: The global chemistry transport model TM5: description and evaluation of the tropospheric chemistry version 3.0, Geosci. Model Develop., 3, 445–473, <a href="http://dx.doi.org/10.5194/gmd-3-445-2010">https://doi.org/10.5194/gmd-3-445-2010</a>, 2010. Kinnison, D.&nbsp;E., Grant, K.&nbsp;E., Connell, P.&nbsp;S., Rotman, D.&nbsp;A., and Wuebbles, D.&nbsp;J.: The chemical and radiative effects of the Mount Pinatubo eruption, J. Geophys. Res., 99, 25,705–25,731, 1994. Krol, M. and Lelieveld, J.: Can the variability in tropospheric OH be deduced from measurements of 1,1,1-trichloroethane (methyl chloroform)?, J. Geophys. Res., 108, 4125, <a href="http://dx.doi.org/10.1029/2002JD002423">https://doi.org/10.1029/2002JD002423</a>, 2003. Lowe, D.&nbsp;C., Manning, M.&nbsp;R., Brailsford, G.&nbsp;W., and Bromley, A.&nbsp;M.: The 1991-1992 atmospheric methane anomaly: Southern hemisphere 13C decrease and growth rate fluctuations, Geophys. Res. Lett., 24, 857–860, <a href="http://dx.doi.org/10.1029/97GL00830">https://doi.org/10.1029/97GL00830</a>, 1997. Madronich, S.: UV radiation in the natural and perturbed atmosphere, in: Einvironmental effects of UV (Ultraviolet) radiation, edited by Tevini, M., 17–69, Lewis Publisher, Boca Raton, Fl, USA, 1993. McCormick, M.&nbsp;P., Thomason, L.&nbsp;W., and Trepte, C.&nbsp;R.: Atmospheric effects of the Mt. Pinatubo eruption, Nature, 373, 399–404, 1995. Monteil, G., Houweling, S., Dlugockenky, E.&nbsp;J., Maenhout, G., Vaughn, B.&nbsp;H., White, J. W.&nbsp;C., and Rockmann, T.: Interpreting methane variations in the past two decades using measurements of CH<sub>4</sub> mixing ratio and isotopic composition, Atmos. Chem. Phys., 11, 9141–9153, <a href="http://dx.doi.org/10.5194/acp-11-9141-2011">https://doi.org/10.5194/acp-11-9141-2011</a>, 2011. Montzka, S.&nbsp;A., Dlugokencky, E.&nbsp;J., and Butler, J.&nbsp;H.: Non-CO2 greenhouse gases and climate change, Nature, 476, 43–50, <a href="http://dx.doi.org/10.1038/nature10322">https://doi.org/10.1038/nature10322</a>, 2011{a}. Montzka, S.&nbsp;A., Krol, M., Dlugokencky, E., Hall, B., Jockel, P., and Lelieveld, J.: Small Interannual Variability of Global Atmospheric Hydroxyl, Science, 331, 67–69, <a href="http://dx.doi.org/10.1126/science.1197640">https://doi.org/10.1126/science.1197640</a>, 2011{b}. Niemeier, U., Timmreck, C., Graf, H.-F., Kinne, S., Rast, S., and Self, S.: Initial fate of fine ash and sulfur from large volcanic eruptions, Atmos. Chem. Phys., 9, 9043–9057, <a href="http://dx.doi.org/10.5194/acp-9-9043-2009">https://doi.org/10.5194/acp-9-9043-2009</a>, 2009. Prather, M., Ehhalt, D., Dentener, F., Derwent, R., Dlugokencky, E., Holland, E., Isaksen, I. S.&nbsp;A., Katima, J., Kirchhoff, V., Matson, P., Midgley, P.&nbsp;M., and Wang, M.: Atmospheric Chemistry and Greenhouse Gases, in: Climate Change 2001: The Scientific Basis, Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate Change, 239–288, Cambridge Univ. Press, New York, USA, 2001. Prinn, R.&nbsp;G., Huang, J., Weiss, R.&nbsp;F., Cunnold, D.&nbsp;M., Fraser, P.&nbsp;J., Simmonds, P.&nbsp;G., McCulloch, A., Harth, C., Reimann, S., Salameh, P., O'Doherty, S., Wang, R. H.&nbsp;J., Porter, L.&nbsp;W., Miller, B.&nbsp;R., and Krummel, P.&nbsp;B.: Evidence for variability of atmospheric hydroxyl radicals over the past quarter century, Geophys. Res. Lett., 32, L07809, <a href="http://dx.doi.org/10.1029/2004GL022228">https://doi.org/10.1029/2004GL022228</a>, 2005. Quay, P., Stutsman, J., Wilbur, D., Snover, A., Dlugokencky, E., and Brown, T.: The isotopic composition of atmospheric methane, Global Biogeochem. Cy., 13, 445–461, <a href="http://dx.doi.org/10.1029/1998GB900006">https://doi.org/10.1029/1998GB900006</a>, 1999. Randel, J.&nbsp;W., Wu, F., Russell III, J., Waters, J., and Froidevaux, L.: Ozone and temperature changes in the stratosphere following the eruption of Mount Pinatubo, Geophys. Res. Lett., 100, 16753–16764, 1995. Ringeval, B., de&nbsp;Noblet-Ducoudré, N., Ciais, P., Bousquet, P., Prigent, C., Papa, F., and Rossow, W.&nbsp;B.: An attempt to quantify the impact of changes in wetland extent on methane emissions on the seasonal and interannual time scales, Global Biogeochem. Cy., 24, GB2003, <a href="http://dx.doi.org/10.1029/2008GB003354">https://doi.org/10.1029/2008GB003354</a>, 2010. Russell, P.&nbsp;B., Livingston, J.&nbsp;M., Pueschel, R.&nbsp;F., Bauman, J.&nbsp;J., Pollack, J.&nbsp;B., Brooks, S.&nbsp;L., Hamill, P., Thomason, L.&nbsp;W., Stowe, L.&nbsp;L., Deshler, T., Dutton, E.&nbsp;G., and Bergstrom, R.&nbsp;W.: Global to microscale evolution of the Pinatubo volcanic aerosol derived from diverse measurements and analyses, J. Geophys. Res., 101, 18745–18763, 1996. Sander, S.&nbsp;P., Friedl, R.&nbsp;R., Barker, J.&nbsp;R., Golden, D.&nbsp;M., Kurylo, M.&nbsp;J., Wine, P.&nbsp;H., Abbatt, J. P.&nbsp;D., Burkholder, J.&nbsp;B., Kolb, C.&nbsp;E., Moortgat, G.&nbsp;K., Huie, R.&nbsp;E., and Orkin, V.&nbsp;L.: Chemical Kinetics and Photochemical Data for Use in Atmospheric Studies, Tech. Rep.&nbsp;17, Jet Propulsation Laboratory, NASA, Pasadena, California, USA, 2011. Schauffler, S.&nbsp;M. and Daniel, J.&nbsp;S.: On the effects of stratospheric circulation changes on trace gas trends, J. Geophys. Res., 99, 25747–25754, 1994. Shindell, D.&nbsp;T., Faluvegi, G., Stevenson, D.&nbsp;S., Krol, M.&nbsp;C., Emmons, L.&nbsp;K., Lamarque, J.-F., Pétron, G., Dentener, F.&nbsp;J., Ellingsen, K., Schultz, M.&nbsp;G., Wild, O., Amann, M., Atherton, C.&nbsp;S., Bergmann, D.&nbsp;J., Bey, I., Butler, T., Cofala, J., Collins, W.&nbsp;J., Derwent, R.&nbsp;G., Doherty, R.&nbsp;M., Drevet, J., Eskes, H.&nbsp;J., Fiore, A.&nbsp;M., Gauss, M., Hauglustaine, D.&nbsp;A., Horowitz, L.&nbsp;W., Isaksen, I. S.&nbsp;A., Lawrence, M.&nbsp;G., Montanaro, V., Müller, J.-F., Pitari, G., Prather, M.&nbsp;J., Pyle, J.&nbsp;A., Rast, S., Rodriguez, J.&nbsp;M., Sanderson, M.&nbsp;G., Savage, N.&nbsp;H., Strahan, S.&nbsp;E., Sudo, K., Szopa, S., Unger, N., van Noije, T. P.&nbsp;C., and Zeng, G.: Multimodel simulations of carbon monoxide: Comparison with observations and projected near-future changes, J. Geophys. Res., 111, D19306, <a href="http://dx.doi.org/10.1029/2006JD007100">https://doi.org/10.1029/2006JD007100</a>, 2006. Soden, B.&nbsp;J., Wetherald, R.&nbsp;T., Stenchikov, G.&nbsp;L., and Robock, A.: Global Cooling After the Eruption of Mount Pinatubo: A Test of Climate Feedback by Water Vapor, Science, 296, <a href="http://dx.doi.org/10.1126/science.296.5568.727">https://doi.org/10.1126/science.296.5568.727</a>, 2002. Spahni, R., Wania, R., Neef, L., van Weele, M., Pison, I., Bousquet, P., Frankenberg, C., Foster, P.&nbsp;N., Joos, F., Prentice, I.&nbsp;C., and van Velthoven, P.: Constraining global methane emissions and uptake by ecosystems, Biogeosciences, 8, 1643–1665, <a href="http://dx.doi.org/10.5194/bg-8-1643-2011">https://doi.org/10.5194/bg-8-1643-2011</a>, 2011. Stevenson, D.&nbsp;S., Dentener, F.&nbsp;J., Schultz, M.&nbsp;G., Ellingsen, K., van Noije, T. P.&nbsp;C., Wild, O., Zeng, G., Amann, M., Atherton, C.&nbsp;S., Bell, N., Bergmann, D.&nbsp;J., Bey, I., Butler, T., Cofala, J., Collins, W.&nbsp;J., Derwent, R.&nbsp;G., Doherty, R.&nbsp;M., Drevet, J., Eskes, H.&nbsp;J., Fiore, A.&nbsp;M., Gauss, M., Hauglustaine, D.&nbsp;A., Horowitz, L.&nbsp;W., Isaksen, I. S.&nbsp;A., Krol, M.&nbsp;C., Lamarque, J.-F., Lawrence, M.&nbsp;G., Montanaro, V., Müller, J.-F., Pitari, G., Prather, M.&nbsp;J., Pyle, J.&nbsp;A., Rast, S., Rodriguez, J.&nbsp;M., Sanderson, M.&nbsp;G., Savage, N.&nbsp;H., Shindell, D.&nbsp;T., Strahan, S.&nbsp;E., Sudo, K., and Szopa, S.: Multimodel ensemble simulations of present-day and near-future tropospheric ozone, J. Geophys. Res., 111, D08301, <a href="http://dx.doi.org/10.1029/2005JD006338">https://doi.org/10.1029/2005JD006338</a>, 2006. Telford, P.&nbsp;J., Lathiere, J., Abraham, N.&nbsp;L., Archibald, A.&nbsp;T., Braesicke, P., Johnson, C.&nbsp;E., Morgenstern, O., O'Connor, F.&nbsp;M., Pike, R.&nbsp;C., Wild, O., Young, P.&nbsp;J., Hewitt, C.&nbsp;N., and Pyle, J.: Effects of climate-induced changes in isoprene emissions after the eruption of Mount Pinatubo, Atmos. Chem. Phys., 7117–7125, <a href="http://dx.doi.org/10.5194/acp-10-7117-2010">https://doi.org/10.5194/acp-10-7117-2010</a>, 2010. Thomason, L.&nbsp;W., Poole, L.&nbsp;R., and Deshler, T.: A Global Climatology Of Stratospheric Aerosol Surface Area Density As Deduced From Stratospheric Aerosol and Gas Experiment II measurements: 1984–1994, J. Geophys. Res., 102, 8967–8976, 1997. Thoning, K.&nbsp;W. and Tans, P.&nbsp;P.: Atmospheric Carbon Dioxide at Mauna Loa Observatory 2. Analysis of the NOAA GMCC Data, 1974–1985, J. Geophys. Res., 94, 8549–8565, 1989. Valentine, D.&nbsp;W., Holland, E.&nbsp;A., and Schimel, D.&nbsp;S.: Ecosystem and physiological controls over methane production in northern wetlands, J. Geophys. Res., 99, 1563–1571, <a href="http://dx.doi.org/10.1029/93JD00391">https://doi.org/10.1029/93JD00391</a>, 1994. Van Aardenne, J.&nbsp;A., Dentener, F.&nbsp;J., Olivier, J. G.&nbsp;J., Klein Goldewijk, C. G.&nbsp;M., and Lelieveld, J.: A High Resolution Dataset of Historical Anthropogenic Trace Gas Emissions for the Period 1890-1990, Global Biogeochem. Cy., 15, 909–928, 2001. Voulgarakis, A., Naik, V., Lamarque, J.-F., Shindell, D.&nbsp;T., Young, P.&nbsp;J., Prather, M.&nbsp;J., Wild, O., Field, R.&nbsp;D., Bergmann, D., Cameron-Smith, P., Cionni, I., Collins, W.&nbsp;J., Dals\o&nbsp;ren, S.&nbsp;B., Doherty, R.&nbsp;M., Eyring, V., Faluvegi, G., Folberth, G.&nbsp;A., Horowitz, L.&nbsp;W., Josse, B., McKenzie, I.&nbsp;A., Nagashima, T., Plummer, D.&nbsp;A., Righi, M., Rumbold, S.&nbsp;T., Stevenson, D.&nbsp;S., Strode, S.&nbsp;a., Sudo, K., Szopa, S., and Zeng, G.: Analysis of present day and future OH and methane lifetime in the ACCMIP simulations, Atmos. Chem. Phys. Discuss., 12, 22945–23005, <a href="http://dx.doi.org/10.5194/acpd-12-22945-2012">https://doi.org/10.5194/acpd-12-22945-2012</a>, 2012. Wang, J.&nbsp;S., Logan, J.&nbsp;A., Mcelroy, M.&nbsp;B., Duncan, B.&nbsp;N., Megretskaia, I.&nbsp;A., and Yantosca, R.&nbsp;M.: A 3-D model analysis of the slowdown and interannual variability in the methane growth rate from 1988 to 1997, Global Biogeochem. Cy., 18, GB3011, <a href="http://dx.doi.org/10.1029/2003GB002180">https://doi.org/10.1029/2003GB002180</a>, 2004. Wang, Y. and Jacob, D.&nbsp;J.: Anthropogenic forcing on tropospheric ozone and OH since preindustrial times, J. Geophys. Res., 103, 31123–31135, 1998. Williams, J.&nbsp;E., Strunk, A., Huijnen, V., and van Weele, M.: The application of the Modified Band Approach for the calculation of on-line photodissociation rate constants in TM5: implications for oxidative capacity, Geosci. Model Develop., 5, 15–35, <a href="http://dx.doi.org/10.5194/gmd-5-15-2012">https://doi.org/10.5194/gmd-5-15-2012</a>, 2012. Wilton, D.&nbsp;J., Hewitt, C.&nbsp;N., and Beerling, D.&nbsp;J.: Simulated effects of changes in direct and diffuse radiation on canopy scale isoprene emissions from vegetation following volcanic eruptions, Atmos. Chem. Phys., 11, 11723–11731, <a href="http://dx.doi.org/10.5194/acp-11-11723-2011">https://doi.org/10.5194/acp-11-11723-2011</a>, 2011.