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Carbon dioxide 'emission' from livestock

 
 
 
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crispy

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why do you care?
Fist off, this isn't a discussion of climate change happening or not, this is just meant for one specific topic, which is if it makes sense the way CO2 emissions are calculated from livestock.

This is the best source I've found on the topic: www.mdpi.com/2071-1050/4/12/3279/pdf

kgCO2 = kgCH4 X 25 + kgN2O x 298 + kgCO2

It basically calculates methane and nitrous oxide into equivalents of CO2. However, I think this doesn't make any sense at all.

First methane, though a stronger GHG is very short lived compared to CO2, so methane doesn't accumulate in the same way that CO2 does. Already there I think they should forget about the x 25 for methane, unless the 25 already takes this into account. Further, a part of a cows diet is just fermented straws and other plant waste from production of crops, so this would either way end up as methane or CO2 no matter that the cows get to eat it first.

Not to mention that all the carbon in the above cycle is actually already in the system, and just passed around by crops, cows and atmosphere, so its not adding anything to the amount of carbon in the system. Only burning fossils do that.

Nitrous oxide im not so sure about though.
 
Animal agriculture contributes more to global warming than all transportation modalities combined.
 
crispy said:
Fist off, this isn't a discussion of climate change happening or not, this is just meant for one specific topic, which is if it makes sense the way CO2 emissions are calculated from livestock.

This is the best source I've found on the topic: www.mdpi.com/2071-1050/4/12/3279/pdf

kgCO2 = kgCH4 X 25 + kgN2O x 298 + kgCO2

It basically calculates methane and nitrous oxide into equivalents of CO2. However, I think this doesn't make any sense at all.

First methane, though a stronger GHG is very short lived compared to CO2, so methane doesn't accumulate in the same way that CO2 does. Already there I think they should forget about the x 25 for methane, unless the 25 already takes this into account. Further, a part of a cows diet is just fermented straws and other plant waste from production of crops, so this would either way end up as methane or CO2 no matter that the cows get to eat it first.
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I think you are correct. This is from the EPA:
"Natural processes in soil and chemical reactions in the atmosphere help remove CH4 from the atmosphere. Methane's lifetime in the atmosphere is much shorter than carbon dioxide (CO2), but CH4 is more efficient at trapping radiation than CO2. Pound for pound, the comparative impact of CH4 on climate change is more than 25 times greater than CO2 over a 100-year period."

So, your link is getting the "X 25" from methane's greater pound per pound efficiency in trapping heat, but failing to adjust for the fact that a kg of methane put into the atmosphere stays there a "much shorter" time.


Not to mention that all the carbon in the above cycle is actually already in the system, and just passed around by crops, cows and atmosphere, so its not adding anything to the amount of carbon in the system. Only burning fossils do that.

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I'm not sure that is a meaningful difference. Carbon footprint refers to the amount of additional CO2 in the atmosphere rather than in some other "sink" (whether trees, permafrost, oceans, or deep under ground).

I think the bigger problem is their attempt to translate all GHGs into CO2 equivalent. It seems to just add confusion. If they want a single combined metric, then just call it GHG footprint.
 
Much shorter is quite an understatement - the half life of methane is about 7 days
 
Deepak said:
Much shorter is quite an understatement - the half life of methane is about 7 days
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Wow. So that makes the half life of CO2 about 1400 times longer (assuming CO2 half life of 27 years). So, 1 kg of methane is actually only equivalent to 0.018 kg of CO2 in terms of its net heat trapping impact, making the equation in the OP link absurdly inaccurate. If this is true, it doesn't speak well of the scientific integrity of the journal "Sustainability", which given it is an "open access" authors-pay-to-publish style journal already has my bs detector set to high.
 
I do agree we should ignore the CO2 from the cow--as we should ignore the CO2 emitted by any living thing. Such emissions are simply part of a loop, CO2 => Plant => animal (=> animal...) => CO2. Cow problems are CH4, NOx, the land needed to raise the cow and the fuel to run the equipment that feeds/maintains the cow. (This includes much of what goes into growing the food the cow ate. If we ate plants instead of animals there would be only 1/10th the farmland needed.)
 
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