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Methane mystery

  1. Oct 31, 2008 #1
    http://www.tgdaily.com/html_tmp/content-view-39973-113.html [Broken]

    Also notice the stubborn misunderstanding:

    Run http://geosci.uchicago.edu/~archer/cgimodels/radiation.html [Broken] with the basic inputs to get an output radiation of 287.844 W/m2. Now put zero in the CO2 box to get 318.396 W/m2, then restore 375 ppmv for CO2 and run with CH4 put at zero: 289.696. So that's rather more than 30 W/m2 versus less than 2 W/m2, demonstrating that it's rather irrelevant, assuming that the MODTRAN algoritm is correct.
    Last edited by a moderator: May 3, 2017
  2. jcsd
  3. Oct 31, 2008 #2


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    Depends if they mean the total effect of all the methane is 25x the total effect of all the CO2 or they mean a molecule of CH4 has 25x the effect of a molecule of CO2.

    Methane is still an effect of human climate change - turning forests into cattle ranches isn't the cow's fault.
  4. Oct 31, 2008 #3
    No I ran a thread about that long time ago. On equal terms at the same concentrations, CO2 is 5-2 times stronger than methane. The number of 22x or 25x or something is only possible if you'd increase both at the current concentration with one ppmv hence the CO2 from 375 to 376 ppm and methane from 1.7 to 2.7 ppmv but then you're talking about 25 times nothing.
  5. Oct 31, 2008 #4


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    Methane only has about 3x the absorbtion of CO2 but there is a lot more of it potentially around if bogs/wetlands die off or hydrates evaporate due to temperature rises.

    I suspect the 25x number came from some model of all these sources and has become a factoid that gets quoted without understanding what it means.

    I thought the object was to nasrty man made evil chemical industrial methane - as opposed to natural cows / wetlands / 'natural so not our fault' methane emissions.
  6. Oct 31, 2008 #5
    I made these MODTRAN runs a few years ago


    showing the difference between methane and carbon dioxide greenhouse effect according to MODTRAN, using the thermal equilibrium principle to convert the delta radiation to temperature effect. This should show that methane is non sequitur

    The methane myth was born when the isotope spikes of the Greenland ice cores showed a strong correlation with the isotopes (alleged temperatures) as can be seen here


    Obviously with the physics not matching, there must be other factors playing a role.
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