5 ms·

Not true between CO2 and methane. The total amount of carbon is the same but in methane form is worse for greenhouse effect.

xyzzyz 4y ago
Methane is worse, but it again doesn’t matter here, because the fields are in steady state not only with CO2, but with methane as well. Methane doesn’t linger in atmosphere forever, it decomposes into CO2 in a decade or so. This means atoms of methane emitted from the fields are pretty much exactly paired with atoms of methane in atmosphere decaying into CO2. This means that methane emitted from the fields doesn’t increase the total amount of methane in the atmosphere, the way burning fossil fuels does with CO2.
- littlestymaar 4y ago
  This reasoning is completely wrong: there's an input and an progressive decay as output, the amount of methane in the atmosphere at any given point is directly related to the input.
  - xyzzyz 4y ago
    Yes, this is exactly what I say in my comment. The amount of methane in the atmosphere is directly proportional to the input rate. That’s why, as I said, in steady state, when the we keep steady the amount of rice under cultivation, the amount of methane in atmosphere is not changing over time. Can you point to which part exactly is “completely wrong”?
    - littlestymaar 4y ago
      > Can you point to which part exactly is “completely wrong”? First you said: > Not really. These GHG emissions from rice are in steady state with the amount of CO2 and methane in the atmosphere. And then now > That’s why, as I said, in steady state, when the we keep steady the amount of rice under cultivation, the amount of methane in atmosphere is not changing over time. These two statements are contradictory. If we assume steady state, then yeah the amount of methane is stable, but changing the way we cultivate rice is the opposite of steady state: if we reduce the methane emissions, then the amount of methane in the atmosphere will decrease that's it.
      - xyzzyz 4y ago
        There is no contradiction between these two statements. They both say the exact same thing: if rice cultivation is in steady state, the amount of CO2 and CH4 in atmosphere due to it is constant. You next say if we change the steady state, the amount of methane in atmosphere will change, but that again is not a contradiction with what I said.
        littlestymaar 4y ago
        So you eventually agree with the statement you disagreed before, that is: > perennial rice may end up reduce GHG emissions substantially. (because that's the starting point of this conversation, and it's the opposite of steady state)
- crazygringo 4y ago
  That doesn't make sense mathematically. Because you could start with zero methane in the atmosphere, just lots of CO2, but the rice would introduce methane. Eventually yes you can get to a steady state of methane, but the point is that the more rice there is, the higher that steady state becomes. Which is bad. So the total amount of methane would absolutely increase. (And if you stopped planting rice at all it would eventually decrease over the subsequent decades.)
  - xyzzyz 4y ago
    Yes, I discuss this in my comment here https://news.ycombinator.com/item?id=35483780 https://news.ycombinator.com/item?id=35483780 The point is, though, that the amount of methane that currently have in atmosphere, is only barely relevant when it comes to how it affects climate from human perspective. If all methane disappeared tomorrow, our climate would be back to 2010, which is hardy a significant change. Nobody would even notice other than climate scientists. Similarly, if we increase the rice cultivation, the amount of methane will increase in the steady state, but the increase will be wholly immaterial, so that it does not affect us in any real way. This is not really “bad”.
    - billiam 4y ago
      >our climate would be back to 2010, which is hardy a significant change. Uh, no. It is quite significant, and a mountain of evidence says that the climate changes from concentrations in the last decade are very significant. You appear to be a denier of anthropogenic climate change who is willing to make silly straw men arguments.
      - xyzzyz 4y ago
        I do happen to remember what the climate looked like in 2010, and I very much do not believe that enormous social and economic projects are warranted to revert the state of climate by 10 years. > You appear to be a denier of anthropogenic climate change who is willing to make silly straw men arguments. You appear to be unable to discuss the issue on merits, but this doesn’t necessitate resorting to ad hominem. You can do better than that.
- twic 4y ago
  Your assumption of steady state is incorrect. The carbon that is being released as methane would otherwise be accumulated in the soil.
  - codethief 4y ago
    Not the OP but: Sure, rice does cause some non-zero amount of CO2/methane in the atmosphere that would otherwise remain stored inside some other plants (or the soil) but, unless we increase rice plantations around the world, this amount will remain constant. Hence, it's a steady state.
- hinkley 4y ago
  Methane is 20x worse, so if you capture 95% of the carbon and emit the rest as methane, you've broken even on GHG. But nothing I'm aware of captures 95% of carbon. Terra Preta might lock up the captured carbon for 100's of years, but producing charcoal is 50% efficient if you optimize for emissions, which most people do not.

xyzzyz 4y ago

Methane is worse, but it again doesn’t matter here, because the fields are in steady state not only with CO2, but with methane as well. Methane doesn’t linger in atmosphere forever, it decomposes into CO2 in a decade or so. This means atoms of methane emitted from the fields are pretty much exactly paired with atoms of methane in atmosphere decaying into CO2. This means that methane emitted from the fields doesn’t increase the total amount of methane in the atmosphere, the way burning fossil fuels does with CO2.

littlestymaar 4y ago
This reasoning is completely wrong: there's an input and an progressive decay as output, the amount of methane in the atmosphere at any given point is directly related to the input.
- xyzzyz 4y ago
  Yes, this is exactly what I say in my comment. The amount of methane in the atmosphere is directly proportional to the input rate. That’s why, as I said, in steady state, when the we keep steady the amount of rice under cultivation, the amount of methane in atmosphere is not changing over time. Can you point to which part exactly is “completely wrong”?
  - littlestymaar 4y ago
    > Can you point to which part exactly is “completely wrong”? First you said: > Not really. These GHG emissions from rice are in steady state with the amount of CO2 and methane in the atmosphere. And then now > That’s why, as I said, in steady state, when the we keep steady the amount of rice under cultivation, the amount of methane in atmosphere is not changing over time. These two statements are contradictory. If we assume steady state, then yeah the amount of methane is stable, but changing the way we cultivate rice is the opposite of steady state: if we reduce the methane emissions, then the amount of methane in the atmosphere will decrease that's it.
    - xyzzyz 4y ago
      There is no contradiction between these two statements. They both say the exact same thing: if rice cultivation is in steady state, the amount of CO2 and CH4 in atmosphere due to it is constant. You next say if we change the steady state, the amount of methane in atmosphere will change, but that again is not a contradiction with what I said.
      - littlestymaar 4y ago
        So you eventually agree with the statement you disagreed before, that is: > perennial rice may end up reduce GHG emissions substantially. (because that's the starting point of this conversation, and it's the opposite of steady state)
crazygringo 4y ago
That doesn't make sense mathematically. Because you could start with zero methane in the atmosphere, just lots of CO2, but the rice would introduce methane. Eventually yes you can get to a steady state of methane, but the point is that the more rice there is, the higher that steady state becomes. Which is bad. So the total amount of methane would absolutely increase. (And if you stopped planting rice at all it would eventually decrease over the subsequent decades.)
- xyzzyz 4y ago
  Yes, I discuss this in my comment here https://news.ycombinator.com/item?id=35483780 https://news.ycombinator.com/item?id=35483780 The point is, though, that the amount of methane that currently have in atmosphere, is only barely relevant when it comes to how it affects climate from human perspective. If all methane disappeared tomorrow, our climate would be back to 2010, which is hardy a significant change. Nobody would even notice other than climate scientists. Similarly, if we increase the rice cultivation, the amount of methane will increase in the steady state, but the increase will be wholly immaterial, so that it does not affect us in any real way. This is not really “bad”.
  - billiam 4y ago
    >our climate would be back to 2010, which is hardy a significant change. Uh, no. It is quite significant, and a mountain of evidence says that the climate changes from concentrations in the last decade are very significant. You appear to be a denier of anthropogenic climate change who is willing to make silly straw men arguments.
    - xyzzyz 4y ago
      I do happen to remember what the climate looked like in 2010, and I very much do not believe that enormous social and economic projects are warranted to revert the state of climate by 10 years. > You appear to be a denier of anthropogenic climate change who is willing to make silly straw men arguments. You appear to be unable to discuss the issue on merits, but this doesn’t necessitate resorting to ad hominem. You can do better than that.
twic 4y ago
Your assumption of steady state is incorrect. The carbon that is being released as methane would otherwise be accumulated in the soil.
- codethief 4y ago
  Not the OP but: Sure, rice does cause some non-zero amount of CO2/methane in the atmosphere that would otherwise remain stored inside some other plants (or the soil) but, unless we increase rice plantations around the world, this amount will remain constant. Hence, it's a steady state.
hinkley 4y ago
Methane is 20x worse, so if you capture 95% of the carbon and emit the rest as methane, you've broken even on GHG. But nothing I'm aware of captures 95% of carbon. Terra Preta might lock up the captured carbon for 100's of years, but producing charcoal is 50% efficient if you optimize for emissions, which most people do not.