A Reexamination of the Tropospheric Methane Cycle: Geophysical Implications

  1. E.T. Sundquist and
  2. W.S. Broecker
  1. Gunnar I. Senum and
  2. Jeffrey S. Gaffney

Published Online: 18 MAR 2013

DOI: 10.1029/GM032p0061

The Carbon Cycle and Atmospheric CO: Natural Variations Archean to Present

The Carbon Cycle and Atmospheric CO: Natural Variations Archean to Present

How to Cite

Senum, G. I. and Gaffney, J. S. (1985) A Reexamination of the Tropospheric Methane Cycle: Geophysical Implications, in The Carbon Cycle and Atmospheric CO: Natural Variations Archean to Present (eds E.T. Sundquist and W.S. Broecker), American Geophysical Union, Washington, D. C.. doi: 10.1029/GM032p0061

Author Information

  1. Environmental Chemistry Division, Department of Applied Science, Brookhaven National Laboratory, Upton, New York 11973

Publication History

  1. Published Online: 18 MAR 2013
  2. Published Print: 1 JAN 1985

ISBN Information

Print ISBN: 9780875900605

Online ISBN: 9781118664322

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Keywords:

  • Carbon cycle (Biogeochemistry)—Congresses;
  • Atmospheric carbon dioxide—Congresses;
  • Geological time—Congresses;
  • Paleothermometry—Congresses;
  • Geology, Stratigraphic—Congresses

Summary

Existing data concerning sources, sinks, and natural isotopic (13C, D, 14C) abundances of atmospheric methane, a greenhouse gas, are reexamined in light of recent indications of an increasing global atmospheric methane burden. This increase has important geophysical implications with regard to greenhouse effects. Previous evaluations of Ehhalt have been revised by updating bacteria source terms and the hydroxyl sink terms. Microorganism-derived source rates have been lowered from 700±130 to 300±140×1012 g yr−1. Sink rates for atmospheric methane are dropped from 635±30 to 280±60×1012 g yr−1. The revised budget is examined with relation to the known δ13C, δD and 14C methane abundances and found to be in reasonable agreement, with recent biogenic source terms accounting for 80–90% of the observed increase. Although there are limited data, existing δ13C and δD yearly trends support this observation. Future needs for measurements are discussed in light of this budget.