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Comment by xyzzyz | Hacker News Reader

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.

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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.)

Yes, I discuss this in my comment here

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”.

>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.

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.

Actually describing the beliefs that you hold is not an ad hominem.

You, however, are claiming that they are unable to discuss the issue - that is.

> Actually describing the beliefs that you hold is not an ad hominem.

There is not a single thing I have said in this thread that can be interpreted as “denial of anthropogenic climate change”. You are welcome to find it and quote it though. On the other hand, there are many places where I very much reaffirm the reality of anthropogenic climate change, for example

Well, we can start with how you pretend that greenhouse gas concentration determines the current temperature, and not the rate of change of temperature. I bet you aren't stupid, so it's either willful ignorance or disingenuity.

I think they are right.

Yes, the more rice there is, the higher the steady state would be.

However, we aren't planting more rice. The ammount of rice grown and methane released is already in steady state.

This is a seperate point than if atmospheric methane would go down if we grew less rice than today.

If you grow more people, we will have more rice. If perennial rice is more profitable, then corn acreage will shrink in favor of rice acreage.

Your assumption of steady state is incorrect. The carbon that is being released as methane would otherwise be accumulated in the soil.

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.

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.

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.

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”?

> 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.

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.

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)

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