References

ACP

Atmospheric Chemistry and Physics

ACP

1680-7324

Copernicus GmbH

Göttingen, Germany

10.5194/acp-12-12021-2012

Climate versus emission drivers of methane lifetime against loss by tropospheric OH from 1860–2100

John

J. G.

¹ Fiore

A. M.

¹ ³ Naik

² Horowitz

L. W.

¹ Dunne

J. P.

Geophysical Fluid Dynamics Laboratory/NOAA, Princeton, New Jersey, USA

UCAR/Geophysical Fluid Dynamics Laboratory, Princeton, New Jersey, USA

now at: Department of Earth and Environmental Sciences, and Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY, USA

19 12 2012

12 24 12021 12036

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/12/12021/2012/acp-12-12021-2012.html

The full text article is available as a PDF file from http://www.atmos-chem-phys.net/12/12021/2012/acp-12-12021-2012.pdf

With a more-than-doubling in the atmospheric abundance of the potent greenhouse gas methane (CH4) since preindustrial times, and indications of renewed growth following a leveling off in recent years, questions arise as to future trends and resulting climate and public health impacts from continued growth without mitigation. Changes in atmospheric methane lifetime are determined by factors which regulate the abundance of OH, the primary methane removal mechanism, including changes in CH4 itself. We investigate the role of emissions of short-lived species and climate in determining the evolution of methane lifetime against loss by tropospheric OH, (τCH4_OH), in a suite of historical (1860–2005) and future Representative Concentration Pathway (RCP) simulations (2006–2100), conducted with the Geophysical Fluid Dynamics Laboratory (GFDL) fully coupled chemistry-climate model (CM3). From preindustrial to present, CM3 simulates an overall 5% increase in τCH4_OH due to a doubling of the methane burden which offsets coincident increases in nitrogen oxide (NOx emissions. Over the last two decades, however, the τCH4_OH declines steadily, coinciding with the most rapid climate warming and observed slow-down in CH4 growth rates, reflecting a possible negative feedback through the CH4 sink. Sensitivity simulations with CM3 suggest that the aerosol indirect effect (aerosol-cloud interactions) plays a significant role in cooling the CM3 climate. The projected decline in aerosols under all RCPs contributes to climate warming over the 21st century, which influences the future evolution of OH concentration and τCH4_OH. Projected changes in τCH4_OH from 2006 to 2100 range from −13% to +4%. The only projected increase occurs in the most extreme warming case (RCP8.5) due to the near-doubling of the CH4 abundance, reflecting a positive feedback on the climate system. The largest decrease occurs in the RCP4.5 scenario due to changes in short-lived climate forcing agents which reinforce climate warming and enhance OH. This decrease is more-than-halved in a sensitivity simulation in which only well-mixed greenhouse gas radiative forcing changes along the RCP4.5 scenario (5% vs. 13%).

References 1

Allan, W., Struthers, H., and Lowe, D. C.: Methane carbon isotope effects caused by atomic chlorine in the marine boundary layer: Global model results compared with Southern Hemisphere measurements, J. Geophys. Res., 112, D04306, http://dx.doi.org/10.1029/2006JD007369doi:10.1029/2006JD007369, 2007.

Austin, J. and Wilson, R. J.: Ensemble simulations of the decline and recovery of stratospheric ozone, J. Geophys. Res., 111, D16314, http://dx.doi.org/10.1029/2005JD006907doi:10.1029/2005JD006907, 2006.

Austin, J. and Wilson, R. J.: Sensitivity of polar ozone to sea surface temperatures and halogen amounts, J. Geophys. Res., 115, D18303, http://dx.doi.org/10.1029/2009JD013292doi:10.1029/2009JD013292, 2010.

Aydin, M., Verhulst, K. R., Saltzmann, E. S., Battle, M. O., Montzka, S. A., Blake, D. R., Tang, Q., and Prather, M. J.: Recent decreases in fossil-fuel emissions of ethane and methane derived from firn air, Nature, 476, 198–201, http://dx.doi.org/10.1038/nature10352doi:10.1038/nature10352, 2011.

Bekki, S. and Law, K. S.: Sensitivity of the atmospheric CH4 growth rate to global temperature changes observed from 1980 to 1992, Tellus, 49, 409–416, 1997.

Berntsen, T. K., Isaksen, I. S. A., Myhre, G., Fuglestvedt, J. S., Stordal, F., Larsen, T. A., Freckleton, R. S., and Shine, K. P.: Effects of anthropogenic emissions on tropospheric ozone and its radiative forcing, J. Geophys. Res., 102, 28101–28126, http://dx.doi.org/10.1029/97JD02226doi:10.1029/97JD02226, 1997.

Bloom, A. A., Palmer, P. I., Fraser, A., Reay, D. S., and Frankenberg, C.: Large-Scale Controls of Methanogenesis Inferred from Methane and Gravity Spaceborne Data, Science, 327, 322–325, 2010.

Bousquet, P., Hauglustaine, D. A., Peylin, P., Carouge, C., and Ciais, P.: Two decades of OH variability as inferred by an inversion of atmospheric transport and chemistry of methyl chloroform, Atmos. Chem. Phys., 5, 2635–2656, http://dx.doi.org/10.5194/acp-5-2635-2005doi:10.5194/acp-5-2635-2005, 2005.

Bousquet, P., Ciais, P., Miller, J. B., Dlugokencky, E. J., Hauglustaine, D. A., Prigent, C., Van der Werf, G. R., Peylin, P., Brunke, E. G., Carouge, C., Langenfels, R. L., Lathiere, J., Papa, F., Ramonet, M., Schmidt, M., Steele, L. P., Tyler, S. C., and White, J.: Contribution of anthropogenic and natural sources to atmospheric methane variability, Nature, 443, 439–443, 2006.

Brasseur, G. J., Kiehl, T., Muller, J. F., Schneider, T., Granier, C., Tie, X. X., and Hauglustaine, D.: Past and future changes in global tropospheric ozone: Impact on radiative forcing, Geophys. Res. Lett., 25, 3807–3810, 1998.

Crutzen, P. J. and Zimmermann, P. H.: The changing photochemistry of the troposphere, Tellus, 43, 136–151, 1991.

Crutzen, P. J., Lawrence, M. G., and Pöschl, U.: On the background photochemistry of tropospheric ozone, Tellus, 51, 123–146, 1999.

Dalsøren, S. B. and Isaksen, I. S. A.: CTM study of changes in tropospheric hydroxyl distribution 1990–2001 and its impact on methane, Geophys. Res. Lett., 33, L23811, http://dx.doi.org/10.1029/2006GL027295doi:10.1029/2006GL027295, 2006.

Denman, K. L., Brasseur, G., Chidthaisong, A., Ciais, P., Cox, P. M., Dickenson, R. E., Hauglustaine, D., Heinze, C., Holland, E., Jacob, D. J., Lohmann, U., Ramachandran, S., da Silva Dias, P. L., Wofsy, S. C., and Zhang, X.: Couplings between changes in the climate system and biogeochemistry, in: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, edited by: Solomon, S., Qin, D., Manning, M., Chen, Z., Marquis, M., Averyt, K. B., Tignor, M., and Miller, H. L., Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 499–587, 2007.

Dentener, F., Peters, W., Krol, M., Van Weele, M., Bergamaschi, P., and Lelieveld, J.: Interannual variability and trend of CH4 lifetime as a measure for OH changes in the 1979–1993 time period, J. Geophys. Res., 108, 4442, http://dx.doi.org/10.1029/2002JD002916doi:10.1029/2002JD002916, 2003.

Dlugokencky, E. J., Masarie, K. A., Lang, P. M., and Tans, P. P.: Continuing decline in the growth rate of the atmospheric methane burden, Nature, 393, 447–450, 1998.

Dlugokencky, E. J., Houweling, S., Bruhwiler, L., Masarie, K. A., Lang, P. M., Miller, J. B., and Tans, P. P.: Atmospheric methane levels off: Temporary pause or a new steady-state?, Geophys. Res. Lett., 30, 1992, http://dx.doi.org/10.1029/2003GL018126doi:10.1029/2003GL018126, 2003.

Dlugokencky, E. J., Bruhwiler, L., White, J. W. C., Emmons, L. K., Novelli, P. C., Montzka, S. A., Masarie, K. A., Lang, P. M., Crotwell, A. M., Miller, J. B., and Gatti, L. V.: Observational constraints on recent increases in the atmospheric CH4 burden, Geophys. Res. Lett., 36, L18803, http://dx.doi.org/10.1029/2009GL039780doi:10.1029/2009GL039780, 2009.

Donner, L. J., Wyman, B. L., Hemler, R. S., Horowitz, L. W., Ming, Y., Zhoa, M., Golaz, J.-C., Ginoux, P., Lin, S.-J., Schwarkopf, M. D., Austin, J., Alaka, G., Cooke, W. F., Delworth, T. L., Freidenreich, S. M., Gordon, C. T., Griffies, S. M., Held, I. M., Hurlin, W. J., Klein, S. A., Knutson, T. R., Langenhorst, A. R., Lee, H.-C., Lin, Y., Magi, B. I., Malyshev, S. L., Milly, P. C. D., Naik, V., Nath, M. J., Pincus, R., Ploshay, J. J., Ramaswamy, V., Seman, C. J., Shevliakova, E., Sirutis, J. J., Stern, W. F., Stouffer, R. J., Stouffer, R. J., Wilson, R. J., Winton, M., Wittenberg, A. T., and Zeng, F.: The dynamical core, physical parameterizations, and basic simulation characteristics of the atmospheric component AM3 of the GFDL Global Coupled Model CM3, J. Climate, 24, 3484–3519, 2011.

Fiore, A. M., Jacob, D. J., Field, B. D., Streets, D. G., Fernandes, S. D., and Jang, C.: Linking ozone pollution and climate change: The case for controlling methane, Geophys. Res. Lett., 29, 1919, http://dx.doi.org/10.1029/2002GL015601doi:10.1029/2002GL015601, 2002.

Fiore, A. M., Horowitz, L. W., Dlugokencky, E. J., and West, J. J.: Impact of meteorology and emissions on methane trends, 1990–2004, Geophys. Res. Lett., 33, L12809, http://dx.doi.org/10.1029/2006GL026199doi:10.1029/2006GL026199, 2006.

Fiore, A. M., West, J. J., Horowitz, L. W., Naik, V., and Schwarzkopf, M. D.: Characterizing the tropospheric ozone response to methane emission controls and the benefits to climate and air quality, J. Geophys. Res., 113, D08307, http://dx.doi.org/10.1029/2007JD009162doi:10.1029/2007JD009162, 2008.

Fiore, A. M., Dentener, F. J., Wild, O., Cuvelier, C., Schultz, M. G., Hess, P., Textor, C., Schulz, M., Doherty, R. M., Horowitz, L. W., MacKenzie, I. A., Sanderson, M. G., Shindell, D. T., Stevenson, D. S., Szopa, S., Van Dingenen, R., Zeng, G., Atherton, C., Bergmann, D., Bey, I., Carmichael, G., Collins, W. J., Duncan, B. N., Faluvegi, G., Folberth, G., Gauss, M., Gong, S. L, Hauglustaine, D., Holloway, T., Isaksen, I. S. A., Jacob, D. J., Jonson, J. E., Kaminski, J. W., Keating, T. J., Lupu, A., Marmer, E., Montanaro, V., Park, R. J., Pitari, G., Pringle, K. J., Pyle, J.A., Schroeder, S., Vivanco, M. G., Wind, P., Wojcik, G., Wu, S., and Zuber, A.: Multimodel estimates of intercontinental source-receptor relationships for ozone pollution, J. Geophys. Res., 114, D04301, doi:04310.01029/02008JD010816, 2009.

Forster, P., Ramaswamy, V., Artaxo, P., Berntsen, T., Betts, R., Fahey, D. W., Haywood, J., Lean, J., Lowe, D. C., Myhre, G., Nganga, J., Prinn, R., and Raga, G., Schulz, M., and Van Dorland, R.: Changes in Atmospheric Constituents and in Radiative Forcing, in: Climate Change 2007: The Physical Science Basis, Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, edited by: Solomon, S., Qin, D., Manning, M., Chen, Z., Marquis, M., Averyt, K. B., Tignor, M., and Miller, H. L., Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 129–234, 2007.

Grenfell, J. L., Shindell, D. T., Koch, D., and Rind, D.: Chemistry-climate interactions in the Goddard Institute general circulation model 2, New insights into modeling the pre-industrial atmosphere, J. Geophys. Res., 106, 33435–33451, 2001.

Griffies, S. M, Winton, M., Donner, L. J., Horowitz, L. W., Downes, S. M., Farneti, R., Gnanadesikan, A., Hurlin, W. J., Lee, H.-C., Liang, Z., Palter, J. B., Samuels, B. L., Wittenberg, A. T., Wyman, B. L., Yin, J., and Zadeh, N.: The GFDL CM3 coupled climate model: Characteristics of the ocean and sea ice simulations, J. Climate, 24, 3520–3544, 2011.

Gupta, M. L., Cicerone, R. J., and Elliot, S.: Perturbation to global tropospheric oxidizing capacity due to latitudinal redistribution of surface sources of NO$_\textx$, CH4 and CO, Geophys. Res. Lett., 25, 3931–3934, 1998.

Hamilton, K. and Fan, S.-M.: Effects of the stratospheric quasi-biennial oscillation on long-lived greenhouse gases in the atmosphere, J. Geophys. Res., 105, 20581–20587, 2000.

Hauglustaine, D. A. and Brasseur, G. P.: Evolution of tropospheric ozone under anthropogenic activities and associated radiative forcing of climate, J. Geophys. Res., 106, 32337–32360, http://dx.doi.org/10.1029/2001JD900175doi:10.1029/2001JD900175, 2001.

Hodson, E. L., Poulter, B., Zimmermann, N. E., Prigent, C., and Kaplan, J. O.: The El Niño – Southern Oscillation and wetland methane interannual variability, Geophys. Res. Lett., 38, L08810, http://dx.doi.org/10.1029/2011GL046861doi:10.1029/2011GL046861, 2011.

Holmes, C. D., Prather, M. J., Søvde, O. A., and Myhre, G.: Future methane, hydroxyl, and their uncertainties: key climate and emission parameters for future predictions, Atmos. Chem. Phys. Discuss., 12, 20931–20974, http://dx.doi.org/10.5194/acpd-12-20931-2012doi:10.5194/acpd-12-20931-2012, 2012.

Horowitz, L. W.: Past, present, and future concentrations of tropospheric ozone and aerosols: methodology, ozone evaluation and sensitivity to aerosol wet removal, J. Geophys. Res., 111, D22211, http://dx.doi.org/10.1029/2005JD006937doi:10.1029/2005JD006937, 2006.

Horowitz, L. W., Walters, S., Mauzerall, D. L., Emmons, L. K., Rasch, P. J., Granier, C., Tie, X., Lamarque, J.-F., Schultz, M. G., Tyndall, G. S., Orlando, J. J., and Brasseur, G. P.: A global simulation of tropospheric ozone and related tracers: description and evaluation of MOZART, version 2, J. Geophys. Res., 108, 4784, http://dx.doi.org/10.1029/2002JD002853doi:10.1029/2002JD002853, 2003.

Johnson, C. E., Stevenson, D. S., Collins, W. J., and Derwent, R. G.: Interannual variability in methane growth rate simulated with a coupled ocean-atmosphere chemistry model, Geophys. Res. Lett., 29, 1903, http://dx.doi.org/10.1029/2002GL015269doi:10.1029/2002GL015269, 2002.

Kai, F. M., Tyler, S. C., Randerson, J. T., and Blake, D. R.: Reduced methane growth rate explained by decreased Northern Hemisphere microbial sources, Nature, 476, 194–197, 2011.

Karlsdóttir, S. and Isaksen, I. S. A.: Changing methane lifetime: Possible cause for reduced growth, Geophys. Res. Lett., 27, 93–96, 2000.

Krol, M., van Leeuwen, P. J., and Lelieveld, J.: Global OH trend inferred from methyl-chloroform measurements, J. Geophys. Res., 103, 10697–10711, 1998.

Labrador, L. J., von Kuhlmann, R., and Lawrence, M. G.: Strong sensitivity of the global mean OH concentration and the tropospheric oxidizing efficiency to the source of NO$_\textx$ from lightning, Geophys. Res. Lett., 31, L06102, http://dx.doi.org/10.1029/2003GL019229doi:10.1029/2003GL019229, 2004.

Labrador, L. J., von Kuhlmann, R., and Lawrence, M. G.: The effects of lightning-produced NO$_\textx$ and its vertical distribution on atmospheric chemistry: sensitivity simulations with MATCH-MPIC, Atmos. Chem. Phys., 5, 1815–1834, http://dx.doi.org/10.5194/acp-5-1815-2005doi:10.5194/acp-5-1815-2005, 2005.

Lamarque, J.-F., Hess, P., Emmons, L., Buja, L., Washington, W., and Granier, C.: Tropospheric ozone evolution between 1890 and 1990, J. Geophys. Res., 110, D08304, http://dx.doi.org/10.1029/2004JD005537doi:10.1029/2004JD005537, 2005.

Lamarque, J.-F., Bond, T. C., Eyring, V., Granier, C., Heil, A., Klimont, Z., Lee, D., Liousse, C., Mieville, A., Owen, B., Schultz, M. G., Shindell, D., Smith, S. J., Stehfest, E., Van Aardenne, J., Cooper, O. R., Kainuma, M., Mahowald, N., McConnell, J. R., Naik, V., Riahi, K., and van Vuuren, D. P.: Historical (1850–2000) gridded anthropogenic and biomass burning emissions of reactive gases and aerosols: methodology and application, Atmos. Chem. Phys., 10, 7017–7039, http://dx.doi.org/10.5194/acp-10-7017-2010doi:10.5194/acp-10-7017-2010, 2010.

Lamarque, J.-F., Shindell, D. T., Josse, B., Young, P. J., Cionni, I., Eyring, V., Bergmann, D., Cameron-Smith, P., Collins, W. J., Doherty, R., Dalsoren, S., Faluvegi, G., Folberth, G., Ghan, S. J., Horowitz, L. W., Lee, Y. H., MacKenzie, I. A., Nagashima, T., Naik, V., Plummer, D., Righi, M., Rumbold, S., Schulz, M., Skeie, R. B., Stevenson, D. S., Strode, S., Sudo, K., Szopa, S., Voulgarakis, A., and Zeng, G.: The Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP): overview and description of models, simulations and climate diagnostics, Geosci. Model Dev. Discuss., 5, 2445–2502, http://dx.doi.org/10.5194/gmdd-5-2445-2012doi:10.5194/gmdd-5-2445-2012, 2012.

Law, K. S. and Nisbet, E. G.: Sensitivity of the methane growth rate to changes in methane emissions from natural gas and coal, J. Geophys. Res., 101, 14387–14397, 1996.

Lawrence, M. G., Jöckel, P., and von Kuhlmann, R.: What does the global mean OH concentration tell us?, Atmos. Chem. Phys., 1, 37–49, http://dx.doi.org/10.5194/acp-1-37-2001doi:10.5194/acp-1-37-2001, 2001.

Lelieveld, J., Crutzen, P. J., and Dentener, F. J.: Changing concentration, lifetime and climate forcing of atmospheric methane, Tellus, 50, 128–150, 1998.

Lelieveld, J., Peters, W., Dentener, F. J., and Krol, M. C.: Stability of tropospheric hydroxyl chemistry, J. Geophys. Res., 107, 4715, http://dx.doi.org/10.1029/2002JD002272doi:10.1029/2002JD002272, 2002.

Lelieveld, J., Dentener, F. J., Peters, W., and Krol, M. C.: On the role of hydroxyl radicals in the self-cleansing capacity of the troposphere, Atmos. Chem. Phys., 4, 2337–2344, http://dx.doi.org/10.5194/acp-4-2337-2004doi:10.5194/acp-4-2337-2004, 2004.

Levy, H.: Normal atmosphere: Large radical and formaldehyde concentrations predicted, Science, 173, 141–143, 1971.

Levy, H., Moxim, W. J., and Kasibhatla, P. S.: A global three-dimensional time-dependent lightning source of tropospheric NO$_\textx$, J. Geophys. Res., 101, 22911–22922, 1996.

Levy, H., Schwarzkopf, M. D., Horowitz, L., Ramaswamy, V., and Findell, K. L.: Strong sensitivity of late 21st century climate to projected changes in short-lived air pollutants, J. Geophys. Res., 113, D06102, http://dx.doi.org/10.1029/2007JD009176doi:10.1029/2007JD009176, 2008.

Logan, J. A., Prather, M. J., Wofsy, S. C., and McElroy, M. B.: Tropospheric Chemistry: A global perspective, J. Geophys. Res., 86, 7210–7254, 1981.

Makkonen, R., Asmi, A., Kerminen, V.-M., Boy, M., Arneth, A., Hari, P., and Kulmala, M.: Air pollution control and decreasing new particle formation lead to strong climate warming, Atmos. Chem. Phys., 12, 1515–1524, http://dx.doi.org/10.5194/acp-12-1515-2012doi:10.5194/acp-12-1515-2012, 2012.

Martinerie, P., Brasseur, G. P., and Granier, C.: The chemical composition of ancient atmospheres: A model study constrained by ice core data, J. Geophys. Res., 100, 14291–14304, 1995.

Meinshausen, M., Smith, S. J., Calvin, K., Daniel, J. S., Kainuma M. L. T., Lamarque, J.-F., Matsumoto, K., Montzka, S. A., Raper, S. C. B., Riahi, K., Thomson, A., Velders, G. J. M., and van Vuuren, D. P. P.: The RCP greenhouse gas concentrations and their extensions from 1765 to 2300, Clim. Change, 109, 213–241, http://dx.doi.org/10.1007/s10584-011-0156-zdoi:10.1007/s10584-011-0156-z, 2011.

Mickley, L. J., Murti, P. P., Jacob, D. J., Logan, J. A., Koch, D. M., and Rind, D.: Radiative forcing from tropospheric ozone calculated with a unified chemistry climate model, J. Geophys. Res., 104, 30153–30172, 1999.

Montzka, S. A., Krol, M., Dlugokencky, E., Hall, B., Jöckel, P., and Lelieveld, J.: Small interannual variability of global atmospheric hydroxyl, Science, 331, 67–69, http://dx.doi.org/10.1126/science.1197640doi:10.1126/science.1197640, 2011.

Moss, R. H., Edmonds, J. A., Hibbard, K. A., Manning, M. R., Rose, S. K., van Vuuren, D. P., Carter, T. R., Emori, S., Kainuma, M., Kram, T., Meehl, G. A., Mitchell, J. F. B., Nakicenovic, N., Riahi, K., Smith, S. J., Stouffer, R. J., Thomson, A. M., Weyant, J. P., and Wilbanks, T. J.: The next generation of scenarios for climate change research and assessment, Nature, 463, 747–756, http://dx.doi.org/10.1038/nature08823doi:10.1038/nature08823, 2010.

Naik, V., Horowitz, L. W., Fiore, A. M., Ginoux, P., Mao, J., Aghedo, A., and Levy, H: Preindustrial to present day impact of changes in short-lived pollutant emissions on atmospheric composition and climate forcing, J. Geophys. Res., in review, 2012a.

Naik, V., Voulgarakis, A., Fiore., A. M., Horowitz, L. W., Lamarque, J.-F., Lin, M., Prather, M. J., Young, P. J., Bergmann, D., Cameron-Smith, P. J., Cionni, I., Collins, W. J., Dalsøren, S., Doherty, R., Eyring, V., Faluvegi, G., Folberth, G. A., Josse, B., Lee, Y. H., McKenzie, I., A., Nagashima, T., van Noije, T. P. C., Plummer, D. A., Righi, M., Rumbold, S. T., Skeie, R., Shindell, D. T., Stevenson, D. S., Strode, S., Sudo., K., Szopa, S., and Zeng, G.: Preindustrial to present day changes in tropospheric hydroxyl radical and methane lifetime from the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP), Atmos. Chem. Phys., 12, 30755–30804, 2012b.

O'Connor, F. M., Boucher, O., Gedney, N., Jones, C. D., Folberth, G. A., Coppell, R., Friedlingstein, P., Collins, W. J., Chappellaz, J., Ridley, J., and Johnson, C. E.: Possible role of wetlands, permafrost, and methane hydrates in the methane cycle under future climate change, a review, Rev. Geophys., 48, RG4005, http://dx.doi.org/10.1029/2010RG000326doi:10.1029/2010RG000326, 2010.

Osborn T. J. and Wigley, T. M. L.: A simple model for estimating methane concentration and lifetime variations, Clim. Dynam., 9, 181–193, 1994.

Prather, M. J.: Lifetimes and eigenstates in atmospheric chemistry, Geophys. Res. Lett., 21, 801–804, 1994.

Prather, M. J. and Spivakovsky, C. M.: Tropospheric OH and the lifetimes of hydrochlorofluorocarbons, J. Geophys. Res., 95, 18723–18729, 1990.

Prather, M., Gauss, M., Berntsen, T., Isaksen, I., Sundet, J., Bey, I., Brasseur, G., Dentener, F., Derwent, R., Stevenson, D., Grenfell, L., Hauglustaine, D., Horowitz, L., Jacob, D., Mickley, L., Lawrence, M G., von Kuhlmann, R., Muller, J.-F., Pitari, G., Rogers, H., Johnson, M., Pyle, J., Law, K., van Weele, M., and Wild, O.: Fresh air in the 21st century?, Geophys., Res. Lett., 30, 1100, http://dx.doi.org/10.1029/2002GL016285doi:10.1029/2002GL016285, 2003.

Prather, M. J., Holmes, C. D., and Hsu, J.: Reactive greenhouse gas scenarios: Systematic exploration of uncertainties and the role of atmospheric chemistry, Geophys. Res. Lett., 39, L09803, http://dx.doi.org/10.1029/2012GL051440doi:10.1029/2012GL051440, 2012.

Price, C., Penner, J., and Prather M.: NO$_\textx$ from lightning, 1. Global distribution based on lightning physics, J. Geophys. Res., 102, 5929–5941, 1997.

Prinn, R. G., Weiss, R. F., Miller, B. R., Huang, J., Alyea, F. N., Cunnold, D. M., Fraser, P. J., Hartley, D. E., and Simmonds, P. G..: Atmospheric trends and lifetime of CH3CCl3 and global OH concentrations, Science, 269, 187–192, 1995.

Prinn, R. G., Huang, J., Weiss, R. F., Cunnold, D. M., Fraser, P. J., Simmonds, P. G., McCulloch, A., Harth, C., Salameh, P., O'Doherty, S., Wang, R. H. J., Porter, L, and Miller, B. R.: Evidence for substantial variations of atmospheric hydroxyl radicals over the past two decades, Science, 292, 1882–1888, 2001.

Prinn, R. G., Huang, J., Weiss, R. F., Cunnold, D. M., Fraser, P. J., Simmonds, P. G., McCulloch, A., Harth, C., Reimann, S., Salameh, P., O'Doherty, S., Wang, R. H. J., Porter, L. W., Miller, B. R., and Krummel, P. B.: Evidence for variability of atmospheric hydroxyl radicals over the past quarter century, Geophys. Res. Lett., 32, L07809, http://dx.doi.org/10.1029/2004GL022228doi:10.1029/2004GL022228, 2005.

Raes, F. and Seinfeld, J. H.: New Directions: Climate change and air pollution abatement: A bumpy road, Atmos. Environ., 43, 5132–5133, http://dx.doi.org/10.1016/j.atmosenv.2009.06.001doi:10.1016/j.atmosenv.2009.06.001, 2009.

Rigby, M., Prinn, R. G., Fraser, P. J., Simmonds, P. G., Langenfelds, R. L., Huang, J., Cunnold, D. M., Steele, L. P., Krummel, P. B., Weiss, R. F., O'Doherty, S., Salameh, P. K., Wang, H. J., Harth, C. M., Mühle, J., and Porter, L. W.: Renewed growth of atmospheric methane, Geophys. Res. Lett., 35, L22805, http://dx.doi.org/10.1029/2008GL036037doi:10.1029/2008GL036037, 2008.

Roelofs, G. J., Lelieveld, J., and van Dorland, R.: A three-dimensional chemistry-general circulation model simulation of anthropogenically derived ozone in the troposphere and its radiative climate forcing, J. Geophys. Res., 102, 23389–23401, 1997.

Sander, S. P., Friedl, R. R., Golden, D. M., Kurylo, M. J., Huie, R. E., Orkin, V. L., Moortgat, G. K., Wine, P. H., Ravishankara, A. R., Kolb, C. E., Molina, M. J., and Finlayson-Pitts, B. J., Huie, R. E., and Orkin, V. L.: Chemical kinetics and photochemical data for use in atmospheric studies, Evaluation Number 15, JPL Publications 06-2, Jet Propulsion Laboratory, Pasadena, CA, USA, 2006.

Shevliakova, E., Pacala S. W., Malyshev S., Hurtt G. C., Milly P. C. D., Caspersen J. P., Sentman L. T., Fisk J. P., Wirth C., and Crevoisier C.: Carbon cycling under 300 years of land use change: Importance of the secondary vegetation sink, Global Biogeochem. Cy., 23, GB2022, http://dx.doi.org/10.1029/2007GB003176doi:10.1029/2007GB003176, 2009.

Shindell, D. T., Grenfell, J. L., Rind, D., Grewe, V., and Price, C.: Chemistry-climate interactions in the Goddard Institute for Space Studies general circulation model 1, Tropospheric chemistry model description and evaluation, J. Geophys. Res., 106, 8047–8075, 2001.

Shindell, D. T., Faluvegi, G., Bell, N., and Schmidt, G. A.: An emissions-based view of climate forcing by methane and tropospheric ozone, Geophys. Res. Lett., 32, L04803, http://dx.doi.org/10.1029/2004GL021900doi:10.1029/2004GL021900, 2005.

Shindell, D. T., Faluvegi, G., Unger, N., Aguilar, E., Schmidt, G. A., Koch, D. M., Bauer, S. E., and Miller, R. L.: Simulations of preindustrial, present-day, and 2100 conditions in the NASA GISS composition and climate model G-PUCCINI, Atmos. Chem. Phys., 6, 4427–4459, http://dx.doi.org/10.5194/acp-6-4427-2006doi:10.5194/acp-6-4427-2006, 2006.

Shindell, D., Kuylenstierna, J. C. I., Vignati, E., Van Dingenen, R., Amann, M., Klimont, Z., Anenberg, S. C., Muller, N. Z., Janssens-Maenhout, G., Raes, F., Schwartz, J., Faluvegi, G., Pozzoli, L., Kupiainen, K., Hoglund-Isaksson, L., Emberson, L., Streets, D., Ramanathan, V., Hicks, K., Oanh, N. T. K., Milly, G., Williams, M., Demkine, V., and Fowler, D.: Simultaneously mitigating near-term climate change and improving human health and food security, Science, 335, 183–189, 2012.

Sofen, E. D., Alexander, B., and Kunasek, S. A.: The impact of anthropogenic emissions on atmospheric sulfate production pathways, oxidants, and ice core $\Delta^17$O(SO$_4^2-$). Atmos. Chem. Phys., 11, 3565–3578, http://dx.doi.org/10.5194/acp-11-3565-2011doi:10.5194/acp-11-3565-2011, 2011.

Søvde, O. A., Hoyle, C. R., Myhre, G., and Isaksen, I. S. A.: The HNO3 forming branch of the HO$_2+$NO reaction: pre-industrial-to-present trends in atmospheric species and radiative forcings, Atmos. Chem. Phys., 11, 8929–8943, http://dx.doi.org/10.5194/acp-11-8929-2011doi:10.5194/acp-11-8929-2011, 2011.

Spivakovsky, C. M., Logan, J. A., Montzka, S. A., Balkanski, Y. J., Foreman-Fowler, M., Jones, D. B. A., Horowitz, L. W., Fusco, A. C., Brenninkmeijer, C. A. M., Prather, M. J., Wofsy, S. C., and McElroy, M. B., Three-dimensional climatological distribution of tropospheric OH: Update and evaluation, J. Geophys. Res., 105, 8931–8980, 2000.

Staffelbach, T., Neftel, A., Stauffer, B., and Jacob, D.: A record of the atmospheric methane sink from formaldehyde in polar ice cores, Nature, 349, 603–605, http://dx.doi.org/10.1038/349603a0doi:10.1038/349603a0, 1991.

Stevenson, D. S., Dentener, F. J., Schultz, M. G., Ellingsen, K., van Noije, T. P. C., Wild, O., Zeng, G., Amann, M., Atherton, C. S., Bell, N., Bergmann, D. J., Bey, I., Butler, T., Cofala, J., Collins, W. J., Derwent, R. G., Doherty, R. M., Drevet, J., Eskes, H. J., Fiore, A. M., Gauss, M., Hauglustaine, D. A., Horowitz, L. W., Isaksen, I. S. A., Krol, M. C., Lamarque, J., Lawrence, M. G., Montanaro, V., Müller, J., Pitari, G., Prather, M. J., Pyle, J. A., Rast, S., Rodriguez, J. M., Sanderson, M. G., Savage, N. H., Shindell, D. T., Strahan, S. E., Sudo, K., and Szopa, S.: Multimodel ensemble simulations of present-day and near-future tropospheric ozone, J. Geophys. Res. Atmos., 111, D08301, http://dx.doi.org/10.1029/2005JD006338doi:10.1029/2005JD006338, 2006.

Taylor, K. E., Stouffer, R. J., and Meehl, G. A.: An Overview of CMIP5 and the Experiment Design, B. Am. Meteorol. Soc., 93, 485–498, http://dx.doi.org/10.1175/BAMS-D-11-00094.1doi:10.1175/BAMS-D-11-00094.1, 2012.

Thompson, A. M., Chappellaz, J. A., Fung, I. Y., and Kucsera, T. L.: The atmospheric CH4 increase since the Last Glacial Maximum. II – Interactions with oxidants, Tellus, 45, 242–257, http://dx.doi.org/10.1034/j.1600-0889.1993.t01-2-00003.xdoi:10.1034/j.1600-0889.1993.t01-2-00003.x, 1993.

Unger, N., Menon, S., Koch, D. M., and Shindell, D. T.: Impacts of aerosol-cloud interactions on past and future changes in tropospheric composition, Atmos. Chem. Phys., 9, 4115–4129, http://dx.doi.org/10.5194/acp-9-4115-2009doi:10.5194/acp-9-4115-2009, 2009.

van Vuuren, D., Edmonds, J., Kainuma, M., Riahi, K., Thomson, A., Hibbard, K., Hurtt, G., Kram, T., Krey, V., Lamarque, J.-F., Masui, T., Meinshausen, M., Nakicenovic, N., Smith, S., and Rose, S.: The representative concentration pathways: an overview, Clim. Change, 109, 5–31, http://dx.doi.org/10.1007/s10584-011-0148-zdoi:10.1007/s10584-011-0148-z, 2011.

Voulgarakis, A., Naik, V., Lamarque, J.-F., Shindell, D. T., Young, P. J., Prather, M. J., Wild, O., Field, R. D., Bergmann, D., Cameron-Smith, P., Cionni, I., Collins, W. J., Dalsøren, S. B., Doherty, R. M., Eyring, V., Faluvegi, G., Folberth, G. A., Horowitz, L. W., Josse, B., McKenzie, I. A., Nagashima, T., Plummer, D. A., Righi, M., Rumbold, S. T., Stevenson, D. S., Strode, S. 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, http://dx.doi.org/10.5194/acpd-12-22945-2012doi:10.5194/acpd-12-22945-2012, 2012.

Wang, J. S., Logan, J. A., McElroy, M. B., Duncan, B. N., Megretskaia, I. A., and Yantosca, R. M.: A 3-D model analysis of the slowdown and interannual variability in the methane growth rate from 1988–1997, Global Biogeochem. Cy., 18, GB3011, http://dx.doi.org/10.1029/2003GB002180doi:10.1029/2003GB002180, 2004.

Wang, Y. and Jacob, J. D.: Anthropogenic forcing on tropospheric ozone and OH since preindustrial times, J. Geophys. Res., 103, 31123–31135, 1998.

Warwick, N. J., Bekki, S., Law, K. S., Nisbet, E. G., and Pyle, J. A.: The impact of meteorology on the interannual growth rate of atmospheric methane, Geophys. Res. Lett., 29, 1947, http://dx.doi.org/10.1029/2002GL015282doi:10.1029/2002GL015282, 2002.

West, J. J., Fiore, A. M., Horowitz, L. W., and Mauzerall, D. L.: Global health benefits of mitigating ozone pollution with methane emission controls, Proc. Natl. Acad. Sci., 103, 3988–3993, http://dx.doi.org/10.1073/pnas.0600201103doi:10.1073/pnas.0600201103, 2006.

Wild, O. and Palmer, P. I.: How sensitive is tropospheric oxidation to anthropogenic emissions?, Geophys. Res. Lett., 35, L22802, http://dx.doi.org/10.1029/2008GL035718doi:10.1029/2008GL035718, 2008.

Young, P. J., Archibald, A. T., Bowman, K. W., Lamarque, J.-F., Naik, V., Stevenson, D. S., Tilmes, S., Voulgarakis, A., Wild, O., Bergmann, D., Cameron-Smith, P., Cionni, I., Collins, W. J., Dalsøren, S. B., Doherty, R. M., Eyring, V., Faluvegi, G., Horowitz, L. W., Josse, B., Lee, Y. H., MacKenzie, I. A., Nagashima, T., Plummer, D. A., Righi, M., Rumbold, S. T., Skeie, R. B., Shindell, D. T., Strode, S. A., Sudo, K., Szopa, S., and Zeng, G.: Pre-industrial to end 21st century projections of tropospheric ozone from the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP), Atmos. Chem. Phys. Discuss., 12, 21615–21677, http://dx.doi.org/10.5194/acpd-12-21615-2012doi:10.5194/acpd-12-21615-2012, 2012.