As with carbon dioxide, the atmospheric methane from 1000 A.D. to 1800 A. D. fluctuated with the global temperature. The fluctuation was about 40 ppb around an average of 695 ppb, with an interpolar difference between 24 and 58ppb. There was a large increase in methane growth rate from 1945 to 1990, peaking at about 17ppb per year in 1981, and falling rapidly after that, and expected to become zero in 2006.with an atmospheric methane concentration of about 1700ppb. These results are backed up by measurements on carbon 13 isotopes. Vincent R. Gray , M.A.,Ph.
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A list of back issues and individual Bulletins are also available on request. The magnitude of this effect is not known and is difficult to quantify, but it could be significant. This assertion is also pertinent to Jarl Ahlbeck's paper recently posted on Daly's web site.