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Recent decreases in fossil-fuel emissions of ethane and methane derived from firn air


Methane and ethane are the most abundant hydrocarbons in the atmosphere and they affect both atmospheric chemistry and climate. Both gases are emitted from fossil fuels and biomass burning, whereas methane (CH4) alone has large sources from wetlands, agriculture, landfills and waste water. Here we use measurements in firn (perennial snowpack) air from Greenland and Antarctica to reconstruct the atmospheric variability of ethane (C2H6) during the twentieth century. Ethane levels rose from early in the century until the 1980s, when the trend reversed, with a period of decline over the next 20 years. We find that this variability was primarily driven by changes in ethane emissions from fossil fuels; these emissions peaked in the 1960s and 1970s at 14–16 teragrams per year (1 Tg = 1012 g) and dropped to 8–10 Tg yr−1 by the turn of the century. The reduction in fossil-fuel sources is probably related to changes in light hydrocarbon emissions associated with petroleum production and use. The ethane-based fossil-fuel emission history is strikingly different from bottom-up estimates of methane emissions from fossil-fuel use1,2, and implies that the fossil-fuel source of methane started to decline in the 1980s and probably caused the late twentieth century slow-down in the growth rate of atmospheric methane3,4.

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Figure 1: Ethane mixing ratios in firn air at three sites, and the atmospheric histories derived from these measurements.
Figure 2: Ethane source emissions and the resulting atmospheric histories.
Figure 3: Ethane and methane emissions from fossil fuels, biofuels and biomass burning.


  1. Stern, D. I. & Kaufmann, R. K. Estimates of global anthropogenic methane emissions 1860–1993. Chemosphere 33, 159–176 (1996)

    Article  ADS  CAS  Google Scholar 

  2. van Aardenne, J. A., Dentener, F. J., Olivier, J. G. J., Klein Goldewijk, C. G. M. & Lelieveld, J. A. 1°x1° resolution data set of historical anthropogenic trace gas emissions for the period 1890–1990. Glob. Biogeochem. Cycles 15, 909–928 (2001)

    Article  ADS  CAS  Google Scholar 

  3. Dlugokencky, E. J. et al. Atmospheric methane levels off: temporary pause or a new steady-state? Geophys. Res. Lett. 30 1992 10.1029/2003GL018126 (2003)

    Article  ADS  CAS  Google Scholar 

  4. Simpson, I. J., Rowland, F. S., Meinardi, S. & Blake, D. R. Influence of biomass burning during recent fluctuations in the slow growth of global tropospheric methane. Geophys. Res. Lett. 33 L22808 10.1029/2006GL027330 (2006)

    Article  ADS  CAS  Google Scholar 

  5. Rudolph, J. The tropospheric distribution and budget of ethane. J. Geophys. Res. 100, 11369–11381 (1995)

    Article  ADS  CAS  Google Scholar 

  6. Xiao, Y. et al. Global budget of ethane and regional constraints on U.S. sources. J. Geophys. Res. 113 D21306 10.1029/2007JD009415 (2008)

    Article  ADS  CAS  Google Scholar 

  7. Boissard, C., Bonsang, B., Kanakidou, M. & Lambert, G. TROPOZ II: global distributions and budgets of methane and light hydrocarbons. J. Atmos. Chem. 25, 115–148 (1996)

    Article  CAS  Google Scholar 

  8. Aydin, M. et al. Post-coring entrapment of modern air in some shallow ice cores collected near the firn-ice transition: evidence from CFC-12 measurements in Antarctic firn air and ice cores. Atmos. Chem. Phys. 10, 5135–5144 (2010)

    Article  ADS  CAS  Google Scholar 

  9. Faïn, X. et al. Mercury in the snow and firn at Summit Station, Central Greenland, and implications for the study of past atmospheric mercury levels. Atmos. Chem. Phys. 8, 3441–3457 (2008)

    Article  ADS  Google Scholar 

  10. Battle, M. et al. Atmospheric gas concentrations over the past century measured in air from firn at the South Pole. Nature 383, 231–235 (1996)

    Article  ADS  CAS  Google Scholar 

  11. Hsu, J., Prather, M. J. & Wild, O. Diagnosing the stratosphere-to-troposphere flux of ozone in a chemistry transport model. J. Geophys. Res. 110 D19305 10.1029/2005JD006045 (2005)

    Article  ADS  Google Scholar 

  12. Prather, M. J., Zhu, X., Strahan, S. E., Steenrod, S. D. & Rodriguez, J. M. Quantifying errors in trace gas species transport modeling. Proc. Natl Acad. Sci. USA 105, 19617–19621 (2008)

    Article  ADS  CAS  Google Scholar 

  13. Pozzer, A. et al. Observed and simulated global distribution and budget of atmospheric C2-C5 alkanes. Atmos. Chem. Phys. 10, 4403–4422 (2010)

    Article  ADS  CAS  Google Scholar 

  14. Dlugokencky, E. J. et al. Observational constraints on recent increases in the atmospheric CH4 burden. Geophys. Res. Lett. 36 L18803 10.1029/2009GL039780 (2009)

    Article  ADS  CAS  Google Scholar 

  15. Rigby, M. et al. Renewed growth of atmospheric methane. Geophys. Res. Lett. 35 L22805 10.1029/2008GL036037 (2008)

    Article  ADS  Google Scholar 

  16. Schultz, M. G. et al. Global wildland fire emissions from 1960 to 2000. Glob. Biogeochem. Cycles 22 GB2002 10.1029/2007GB003031 (2008)

    Article  ADS  CAS  Google Scholar 

  17. Remer, D. S. & Jorgens, C. Ethylene economics and production forecasting in a changing environment. Eng. Process Econ. 3, 267–278 (1978)

    Article  Google Scholar 

  18. Barns, D. W. & Edmonds, J. A. An Evaluation of the Relationship Between the Production and Use of Energy and Atmospheric Methane Emissions (TR047, DOE/NBB-0088P, National Technical Information Service, US Dept of Commerce, Springfield, 1990)

    Google Scholar 

  19. Gilardoni, A. The World Market for Natural Gas; Implications for Europe (Springer, 2008)

    Book  Google Scholar 

  20. Bousquet, P. et al. Contribution of anthropogenic and natural sources to atmospheric methane variability. Nature 443, 439–443 (2006)

    Article  ADS  CAS  Google Scholar 

  21. Prinn, R. G. et al. Evidence for variability of atmospheric hydroxyl radicals over the past quarter century. Geophys. Res. Lett. 32 L07809 10.1029/2004GL022228 (2005)

    Article  ADS  CAS  Google Scholar 

  22. Montzka, S. A. et al. Small interannual variability of global atmospheric hydroxyl. Science 331, 67–69 (2011)

    Article  ADS  CAS  Google Scholar 

  23. Lawler, M. J. et al. Pollution-enhanced reactive chlorine chemistry in the eastern tropical Atlantic boundary layer. Geophys. Res. Lett. 36 L08810 10.1029/2008GL036666 (2009)

    Article  ADS  CAS  Google Scholar 

  24. Thornton, J. A. et al. A large atomic chlorine source inferred from mid-continental reactive nitrogen chemistry. Nature 464, 271–274 (2010)

    Article  ADS  CAS  Google Scholar 

  25. Allan, W., Struthers, H. & 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 10.1029/2006JD007369 (2007)

    Article  ADS  CAS  Google Scholar 

  26. Aydin, M., Williams, M. B. & Saltzman, E. S. Feasibility of reconstructing paleoatmopsheric records of selected alkanes, methyl halides, and sulfur gases from Greenland ice cores. J. Geophys. Res. 112 D07312 10.1029/2006JD008027 (2007)

    Article  ADS  CAS  Google Scholar 

  27. Prather, M. et al. in Climate Change 2001: The Scientific Basis (eds Hougton, J. T. et al.) (Cambridge Univ. Press, 2001)

    Google Scholar 

  28. MacFarling Meure, C. et al. Law Dome CO2, CH4, and N2O ice core records extended to 2000 years BP. Geophys. Res. Lett. 33 L14810 10.1029/2006GL026152 (2006)

    Article  ADS  CAS  Google Scholar 

  29. Tang, Q. & Prather, M. J. Correlating tropospheric column ozone with tropopause folds: the Aura-OMI satellite data. Atmos. Chem. Phys. 10, 9681–9688 (2010)

    Article  ADS  CAS  Google Scholar 

  30. Andreae, M. O. & Merlet, P. Emission of trace gases and aerosols from biomass burning. Glob. Biogeochem. Cycles 15, 955–966 (2001)

    Article  ADS  CAS  Google Scholar 

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We thank T. Sowers, M. Drier and ICDS drillers for support during firn-air sampling and drilling in the field, and T. Sowers for discussions during preparation of the manuscript. We thank M. Bender and J. Severinghaus for 15N measurements in firn air, S. Meinardi for ethane measurements in surface flasks, and P. Tans and P. Lang for firn-air CO2 data. This work was supported by the National Science Foundation (grants ANT-0739598, ANT-0440602, ANT-0440509, ARC-0520460) and NASA (grant NAG58935).

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Authors and Affiliations



M.A.: firn-air sampling, ethane analysis in firn air and surface-air flasks, firn-air modelling, two-box modelling, box-model inversions, manuscript preparation. K.R.V.: ethane analysis in firn air and surface-air flasks, firn-air modelling, two-box modelling, firn-air and two-box model inversions, manuscript improvements. E.S.S.: firn-air modelling, two-box modelling, firn-air and two-box model inversions, manuscript improvements. M.O.B.: firn-air sampling, firn-air modelling, manuscript improvements. S.A.M.: halocarbon measurements in firn air to constrain firn processes, NOAA surface air samples, manuscript improvements. D.R.B.: ethane measurements in surface air, manuscript improvements. Q.T.: CTM modelling, manuscript improvements. M.J.P.: CTM modelling, manuscript improvements.

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Correspondence to Murat Aydin.

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Supplementary information

Supplementary Information

This file contains Supplementary Text and Data, additional references, Supplementary Figures 1-10 with legends and Supplementary Tables 1-2. (PDF 2094 kb)

Supplementary Data

This file contains the Firn air ethane data. (XLS 10 kb)

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Aydin, M., Verhulst, K., Saltzman, E. et al. Recent decreases in fossil-fuel emissions of ethane and methane derived from firn air. Nature 476, 198–201 (2011).

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