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Andre
Joined: 21 Jul 2007
Posts: 298
Location: Germany - The Nederlands
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 Posted: Wed Nov 21, 2007 6:22 pm Post subject: The methane myth |
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With regular intervals it is posted that methane is a much more powerful greenhouse gas than CO2 and therefore belching cows should be made extinct as soon as possible.
This is also suggested here, calculating global warming potential.
| Quote: | | The GWP is defined as the ratio of the time-integrated radiative forcing from the instantaneous release of 1 kg of a trace substance relative to that of 1 kg of a reference gas. |
And for methane we see values as 12x 72x etc ad powerful as CO2.
Now the bottom line here is the equal amount of gas to be released and the logaritmic relationship of concentration GHG with radiative forcing.
One can run MODTRAN (link see fig) using the radiative balance and see which temperature increases are required to restore radiative balance. These are the results for CO2 and methane
Now on a logaritmic scale one can see the almost linear increase for instance the change in temperature between 1 and 10 ppm is about the same as an increase from 100 ppm to 1000 ppm. So, talking about 1kg CH4 versus 1 kg CO2 or equal units and assume it to be 1 ppm
So the increase of 1 ppm for ~380 ppmv is practically nothing but the increase of 1 ppm for 1.7 ppm CH4 is quite a lot, some 12 times practically nothing or 72 times nothing or whatever times practically nothing. It's all insignificant.
CH4 is in reality less than half effective as a greenhouse gas as CO2 and the GWP has been invented for more effective scaremongering.
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billiards
Site Admin
Joined: 21 Jul 2007
Posts: 81
Location: London, UK
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| Posted: Tue Dec 04, 2007 7:59 pm Post subject: |
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Not sure I understand the argument here.
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Now on a logaritmic scale one can see the almost linear increase for instance the change in temperature between 1 and 10 ppm is about the same as an increase from 100 ppm to 1000 ppm. So, talking about 1kg CH4 versus 1 kg CO2 or equal units and assume it to be 1 ppm |
Are you suggesting the lines on your graph are linear? If so, they're clearly not!
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So the increase of 1 ppm for ~380 ppmv is practically nothing but the increase of 1 ppm for 1.7 ppm CH4 is quite a lot, some 12 times practically nothing or 72 times nothing or whatever times practically nothing. It's all insignificant. |
Where are all the numbers coming from? |
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Andre
Joined: 21 Jul 2007
Posts: 298
Location: Germany - The Nederlands
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| Posted: Tue Dec 04, 2007 8:41 pm Post subject: |
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| billiards wrote: | Not sure I understand the argument here.
Are you suggesting the lines on your graph are linear? If so, they're clearly not! |
No I'm trying to show that they are nearly logaritmic, since not everybody is familiar with logaritmic functions that they shows up like an aparant straight line (linear) on a logaritmic scale.
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Where are all the numbers coming from? |
380 amd 1.7 ppmv resemble current concentrations of CO2 and CH4. Calculations with increases are done with MODTRAN
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