Methane mystery

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http://www.tgdaily.com/html_tmp/content-view-39973-113.html [Broken]

Scientists at MIT have recorded a nearly simultaneous world-wide increase in methane levels. This is the first increase in ten years, and what baffles science is that this data contradicts theories stating man is the primary source of increase for this greenhouse gas. It takes about one full year for gases generated in the highly industrial northern hemisphere to cycle through and reach the southern hemisphere. However, since all worldwide levels rose simultaneously throughout the same year, it is now believed this may be part of a natural cycle in mother nature - and not the direct result of man's contributions.
Also notice the stubborn misunderstanding:

Methane accounts for roughly one-fifth of greenhouse gases in the atmosphere, though its effect is 25x greater than that of carbon dioxide.
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.
 
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mgb_phys
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Methane accounts for roughly one-fifth of greenhouse gases in the atmosphere, though its effect is 25x greater than that of carbon dioxide.
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.
 
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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.
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.
 
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mgb_phys
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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.
 
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I made these MODTRAN runs a few years ago

modtran-rad-bal.GIF


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


http://www.ncdc.noaa.gov/paleo/pubs/flueckiger2004/fig9.gif

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

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