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>Methane, by contrast, is mostly removed from the atmosphere by chemical reaction, persisting for about 12 years. Thus although methane is a potent greenhouse g

>Methane, by contrast, is mostly removed from the atmosphere by chemical reaction, persisting for about 12 years. Thus although methane is a potent greenhouse gas, its effect is relatively short-lived. https://www.theguardian.com/environment/2012/jan/16/greenhouse-gases-remain-air https://www.theguardian.com/environment/2012/jan/16/greenhou...

revax 7y ago
That why we look at the "global warming potential" [1]. But even with a time horizon of 100 years, methane is still 30 times potent than CO2. How can it be irrelevant? [1] https://en.wikipedia.org/wiki/Global_warming_potential https://en.wikipedia.org/wiki/Global_warming_potential
- Merrill 7y ago
  The numerator integral must decline rapidly as a function of TH unless the radiative efficiency is a strong function of time, which seems unlikely. Most of the actual warming effect of a methane release would occur in the first three decades, after which there would be a long tail of slight warming. Methane is not irrelevant, but "global warming potential" seems to obscure the actual time varying nature of the relative impacts. Methane is actually a much stronger greenhouse gas than carbon dioxide in the short run and less strong in the long run that global warming potential would indicate.
- MikeSchurman 7y ago
  30 times more potent for a similar mass. But we emit far far more CO2 than methane. To know if it's important you'd need to know by how much.
  - revax 7y ago
    Well, methane is one the reasons why livestock and paddy fields emit so much greenhouse gases. These two examples are not insignificant.
    - jessaustin 7y ago
      Significance is almost beside the point. Any methane "emitted" by livestock is already present in the carbon cycle: cows eat grass which is made of atmospheric carbon. It isn't sensible to compare that to carbon from fossil fuels. This "methane is worse" proposition was used to argue that livestock production is as bad as burning fossil fuels, but of course that completely falls apart if the main problem with methane is the carbon dioxide into which it degrades. That carbon dioxide may have been methane for the last 12 years, but immediately before that it was grass and immediately before that it was the same existing carbon dioxide that it is again now. There isn't something magical about a cow's gut that somehow multiplies carbon levels.
      - hansbo 7y ago
        This has always been my thought as well, and I have never gotten a good explanation as to why it's wrong. If anyone has one I would love to hear it.
        KirinDave 7y ago
        It was explained to me as: "even if an activity is carbon neutral, if it increases the net free atmospheric carbon it can have a negative effect." The areas we devote to cattle raising are increasing (often at the cost of carbon fixing native flora). So the amount of free methane and carbon are on the rise just by nature of human expansion. I'm not sure that is the whole story, but I always found that explanation helpful for questions like, "Why can't we switch to using charcoal based local power if its carbon neutral?"
      - revax 7y ago
        You are right saying that the carbon cycle is a closed cycle, there is no net change over time in carbon dioxide concentrations (as you are not using fossile fuels or burying grass). But during the 12 years lifespan of methane you will have considerably more radiative forcing.
      - newscracker 7y ago
        > Any methane "emitted" by livestock is already present in the carbon cycle: cows eat grass which is made of atmospheric carbon. It isn't sensible to compare that to carbon from fossil fuels. Considering that: a. most cows in today’s world don’t eat grass, or rather, they eat a lot more soy, corn and other foods grown for them b. the feed for the cows is grown using conventional methods to keep costs under control, which also implies using fertilizers that are produced from fossil fuels (also add the fossil fuels used in the transport of feed as well as the animals) I don’t understand how your entire argument holds true. Seems like there are gaps in your model of the world.
Brakenshire 7y ago
And then it breaks down to CO2. That is a basic and well understood part of climate science, that’s how the calculations are made which show an 80 fold higher impact for Methane per unit mass than for CO2 over a 20 year period, and 20 fold higher impact over a 100 year period. As the climate scientist says in the article, this doesn’t disprove mainstream climate science, and the calculations are correct but banal, and just presented in a way to give a misleading impression of a smaller impact. The author is quite open about preparing the paper specifically to give ammunition to efforts to roll back Oil and Gas regulations.
- romaaeterna 7y ago
  Methane is 16.04 g/mol and CO2 is 44.01 g/mol. PPM of CO2 is 415 and PPM of Methane is something like 1.8 PPM. Increase in CO2 is something like 15PPM/decade. Increase in Methane is 0.1PPM/decade (or less). So in absolute terms, the relative effect of Methane compared to CO2, using the 80x figure is (1.8 * 16 * 80) / (415*44.01) = 12.6%. And in growth terms, the relative effect of Methane is 19%. However, since methane is limited by total land under cultivation, and it has actual hit a stable PPM in the last decade (unlike CO2 which grows exponentially), CO2 is by far the larger component in any climate models projecting into the future. In conclusion, Former White House adviser can actually math while your 80x figure needed to be put into context. I do not know where you get your information from, but I expect that it is from someone trying to make a tendentious environmental case against cows more than it's about someone trying to present unbiased facts.
  - tremon 7y ago
    since methane is limited by total land under cultivation This isn't true. There have been numerous stories of methane stores (e.g. Siberia) that have begun leaking in recent years.
    - romaaeterna 7y ago
      Don't get your news from the places peddling that stuff. Here is what CH4 has been doing since 1985 (notice ppb, not ppm): https://imgur.com/gaKEU3g https://imgur.com/gaKEU3g

revax 7y ago

That why we look at the "global warming potential" [1]. But even with a time horizon of 100 years, methane is still 30 times potent than CO2. How can it be irrelevant? [1] https://en.wikipedia.org/wiki/Global_warming_potential https://en.wikipedia.org/wiki/Global_warming_potential

Merrill 7y ago
The numerator integral must decline rapidly as a function of TH unless the radiative efficiency is a strong function of time, which seems unlikely. Most of the actual warming effect of a methane release would occur in the first three decades, after which there would be a long tail of slight warming. Methane is not irrelevant, but "global warming potential" seems to obscure the actual time varying nature of the relative impacts. Methane is actually a much stronger greenhouse gas than carbon dioxide in the short run and less strong in the long run that global warming potential would indicate.
MikeSchurman 7y ago
30 times more potent for a similar mass. But we emit far far more CO2 than methane. To know if it's important you'd need to know by how much.
- revax 7y ago
  Well, methane is one the reasons why livestock and paddy fields emit so much greenhouse gases. These two examples are not insignificant.
  - jessaustin 7y ago
    Significance is almost beside the point. Any methane "emitted" by livestock is already present in the carbon cycle: cows eat grass which is made of atmospheric carbon. It isn't sensible to compare that to carbon from fossil fuels. This "methane is worse" proposition was used to argue that livestock production is as bad as burning fossil fuels, but of course that completely falls apart if the main problem with methane is the carbon dioxide into which it degrades. That carbon dioxide may have been methane for the last 12 years, but immediately before that it was grass and immediately before that it was the same existing carbon dioxide that it is again now. There isn't something magical about a cow's gut that somehow multiplies carbon levels.
    - hansbo 7y ago
      This has always been my thought as well, and I have never gotten a good explanation as to why it's wrong. If anyone has one I would love to hear it.
      - KirinDave 7y ago
        It was explained to me as: "even if an activity is carbon neutral, if it increases the net free atmospheric carbon it can have a negative effect." The areas we devote to cattle raising are increasing (often at the cost of carbon fixing native flora). So the amount of free methane and carbon are on the rise just by nature of human expansion. I'm not sure that is the whole story, but I always found that explanation helpful for questions like, "Why can't we switch to using charcoal based local power if its carbon neutral?"
    - revax 7y ago
      You are right saying that the carbon cycle is a closed cycle, there is no net change over time in carbon dioxide concentrations (as you are not using fossile fuels or burying grass). But during the 12 years lifespan of methane you will have considerably more radiative forcing.
    - newscracker 7y ago
      > Any methane "emitted" by livestock is already present in the carbon cycle: cows eat grass which is made of atmospheric carbon. It isn't sensible to compare that to carbon from fossil fuels. Considering that: a. most cows in today’s world don’t eat grass, or rather, they eat a lot more soy, corn and other foods grown for them b. the feed for the cows is grown using conventional methods to keep costs under control, which also implies using fertilizers that are produced from fossil fuels (also add the fossil fuels used in the transport of feed as well as the animals) I don’t understand how your entire argument holds true. Seems like there are gaps in your model of the world.

Brakenshire 7y ago

And then it breaks down to CO2. That is a basic and well understood part of climate science, that’s how the calculations are made which show an 80 fold higher impact for Methane per unit mass than for CO2 over a 20 year period, and 20 fold higher impact over a 100 year period. As the climate scientist says in the article, this doesn’t disprove mainstream climate science, and the calculations are correct but banal, and just presented in a way to give a misleading impression of a smaller impact. The author is quite open about preparing the paper specifically to give ammunition to efforts to roll back Oil and Gas regulations.

romaaeterna 7y ago
Methane is 16.04 g/mol and CO2 is 44.01 g/mol. PPM of CO2 is 415 and PPM of Methane is something like 1.8 PPM. Increase in CO2 is something like 15PPM/decade. Increase in Methane is 0.1PPM/decade (or less). So in absolute terms, the relative effect of Methane compared to CO2, using the 80x figure is (1.8 * 16 * 80) / (415*44.01) = 12.6%. And in growth terms, the relative effect of Methane is 19%. However, since methane is limited by total land under cultivation, and it has actual hit a stable PPM in the last decade (unlike CO2 which grows exponentially), CO2 is by far the larger component in any climate models projecting into the future. In conclusion, Former White House adviser can actually math while your 80x figure needed to be put into context. I do not know where you get your information from, but I expect that it is from someone trying to make a tendentious environmental case against cows more than it's about someone trying to present unbiased facts.
- tremon 7y ago
  since methane is limited by total land under cultivation This isn't true. There have been numerous stories of methane stores (e.g. Siberia) that have begun leaking in recent years.
  - romaaeterna 7y ago
    Don't get your news from the places peddling that stuff. Here is what CH4 has been doing since 1985 (notice ppb, not ppm): https://imgur.com/gaKEU3g https://imgur.com/gaKEU3g