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Perennial rice: Plant once, harvest again and again

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Re: Perennial rice: Plant once, harvest again and again

#191

Post by CrazyStat »

photochemsyn wrote: post #155
CrazyStat wrote: post #136

Earlier quoted context omitted.

> and while there is some anaerobic production of methane in rice paddies, the methane gets converted back to CO2 in the atmosphere with a half-life of 10-20 years IIRC. Methane is a far, far worse greenhouse gas than CO2, even accounting for the fact that it eventually decays back to CO2.

Methane is something like 25 times as effective at absorbing outgoing infrared radiation in the Earth's atmosphere relative to carbon dioxide, but there is > 200 times as much CO2 in the atmosphere as methane (1.9 ppm vs 420 ppm). https://www.noaa.gov/news-release/increase-in-atmospheric-me... So the net effect of all the methane is about 50 ppm. About 30% comes from fossil fuels. This leaves a big burp relative to p…

> Methane is something like 25 times as effective at absorbing outgoing infrared radiation in the Earth's atmosphere relative to carbon dioxide, but there is > 200 times as much CO2 in the atmosphere as methane (1.9 ppm vs 420 ppm).

No, this is incorrect. The number you cite (25x) is a 100-year global warming potential (GWP) figure. That is, if I release 1 ton of methane into the atmosphere today, over the next hundred years it will contribute to global warming about as much as if I'd released 25 tons of CO2.

But this is not an appropriate way to analyze the composition of the atmosphere at a point in time. We're not releasing 1.9 tons of methane and 420 tons of CO2 and looking at how that will effect global warming over the next 100 years. Instead we're looking at the CO2 that has built up over the past few hundred years, and the methane that has built up over the past few decades, and looking at how that affects global warming now. We want to integrate over past contributions and look at the resulting warming at a point in time rather than look at emissions at a point of time and integrate over future warming.

The effect of methane when you look at it this way is much higher. The IPCC estimates[1] that methane radiative forcing (i.e contribution to global warming at a point in time, based on current atmospheric concentration) is about 0.48 W/m^2, vs. 1.82 W/m^2 for CO2. That is, the ratio of (warming due to methane) to (warming due to CO2) is about 1:3.8, not 1:8.4 (50 ppm:420 ppm from your calculation). More than twice as bad as the calculation based on GWP!

The good news is that since methane has a short half life, if we can cut methane emissions that portion of the total radiative forcing will respond quickly (1-2 decades). Cutting CO2 emissions takes much longer to show effects.

[1] https://www.ipcc.ch/site/assets/uploads/2018/02/WG1AR5_Chapt...

Re: Perennial rice: Plant once, harvest again and again

#192

Post by TurkishPoptart »

ericpauley wrote: post #100
ccooffee wrote: post #32

Earlier quoted context omitted.

I hadn't heard about rice fields emitting methane before. I was able to quickly find an article, "Methane emissions from global rice fields: Magnitude, spatiotemporal patterns, and environmental controls"[0], which states: > Our study estimated that CH4 emissions from global rice fields varied from 18.3 ± 0.1 Tg CH4/yr (Avg. ±1 SD) under intermittent irrigation to 38.8 ± 1.0 Tg CH4/yr under continuous flooding in the…

To be fair, rice also provides ~20% of global caloric needs, so this isn’t necessarily an outsized contribution.

I couldn't give a damn about carbon emissions, provided people have food.

Re: Perennial rice: Plant once, harvest again and again

#193

Post by photochemsyn »

CrazyStat wrote: post #191
photochemsyn wrote: post #155

Earlier quoted context omitted.

Methane is something like 25 times as effective at absorbing outgoing infrared radiation in the Earth's atmosphere relative to carbon dioxide, but there is > 200 times as much CO2 in the atmosphere as methane (1.9 ppm vs 420 ppm). https://www.noaa.gov/news-release/increase-in-atmospheric-me... So the net effect of all the methane is about 50 ppm. About 30% comes from fossil fuels. This leaves a big burp relative to p…

> Methane is something like 25 times as effective at absorbing outgoing infrared radiation in the Earth's atmosphere relative to carbon dioxide, but there is > 200 times as much CO2 in the atmosphere as methane (1.9 ppm vs 420 ppm). No, this is incorrect. The number you cite (25x) is a 100-year global warming potential (GWP) figure. That is, if I release 1 ton of methane into the atmosphere today, over the next hundr…

Look, the only plausible route to stabilizing the atmospheric chemical composition is to stop pumping carbon out of geological reservoirs into the atmosphere.

That's really all there is to it, you have to eliminate fossil fuels from the system if you believe climate change is a real issue.

Of course, at this point, even that won't stop the climate from steadily warming for the rest of your life, i.e. for the next 100 years at least. The trigger has been pulled.

I advise against buying property on the coasts, in flood plains, etc.

Re: Perennial rice: Plant once, harvest again and again

#194

Post by codethief »

twic wrote: post #87
xyzzyz wrote: post #53

Earlier quoted context omitted.

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 in…

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.

Re: Perennial rice: Plant once, harvest again and again

#195

Post by codethief »

thfuran wrote: post #138
photochemsyn wrote: post #133

Earlier quoted context omitted.

This is a bit overblown. The methane being emitted is sourced originally from atmospheric CO2 via photosynthesis, and while there is some anaerobic production of methane in rice paddies, the methane gets converted back to CO2 in the atmosphere with a half-life of 10-20 years IIRC. This is fundamentally different from natural gas emissions, in which carbon atoms are being transferred from stable geological reservoirs…

Atmospheric methane has a half-life of about 10 years and is well over 10x as greenhouse effecting as CO2. Converting atmospheric CO2 to atmospheric methane is less bad than releasing sequestered methane into the atmosphere but still terrible.

> Converting atmospheric CO2 to atmospheric methane is less bad than releasing sequestered methane into the atmosphere but still terrible.

Sure, if this conversion led to more and more methane in the atmosphere, it would be terrible. In this case, however, the overall amount of methane in the atmosphere due to rice will stay the same, since it's a cycle.

Re: Perennial rice: Plant once, harvest again and again

#196

Post by xyzzyz »

fwip wrote: post #160
xyzzyz wrote: post #111

Earlier quoted context omitted.

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 ca…

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

Re: Perennial rice: Plant once, harvest again and again

#197

Post by ramblenode »

wolfgangK wrote: post #139
Aromasin wrote: post #106

Earlier quoted context omitted.

To put this into context, animal agriculture is responsible for 18% of the worlds CO2 emissions, uses 83% of the world's farmland, but only produces 18% of our calories and 37% of our protein.

I really wish there was a name (that I knew of) for this logical fallacy of using precise quantities of meaninglessly confused categories. What do you think "farmland" is ? Our ancestors who knew how to raise cattle and farm cereals for millennia were surviving on the verge of starvation : why do you think that was ? Were they so dumb they'd rather die of hunger than convert some of their grazing pastures to cereal a…

This is a kind of "wronger than wrong" fallacy [0]. Yes, not all pasture land is suitable for cereal crops. But that doesn't negate the fact that most livestock production does present an inefficient tradeoff when optimizing for nutrition and land/climate impact.

This is because a) a large portion of cereal crops are diverted to feed livestock and b) very little livestock comes from natural pasture land. So only a miniscule percent of livestock production represents no land use tradeoff whatsoever.

a) 40% of cereal crops go toward animal feed [1] and most modern animal agriculture would be impossible without this. Arable land that could be feeding humans is being used to feed animals which then feed humans. That represents roughly a 90% loss of potential biological productivity [2].

b) Despite the US having some of the largest natural pasture, only 4% of retail beef in the US is grass-fed--meaning only a tiny percent are fed exclusively from pasture [3]. Additionally, most pasture land has been converted from forest. 40% of deforestation overall is due to animal agriculture [4]. This is only a little less than plant-based agriculture which provides sinificantly more food.

[0] https://en.wikipedia.org/wiki/Wronger_than_wrong

[1] https://ourworldindata.org/grapher/cereal-distribution-to-us...

[2] https://en.wikipedia.org/wiki/Trophic_level

[3] https://extension.sdstate.edu/grass-fed-beef-market-share-gr...

[4] https://www.fao.org/newsroom/detail/cop26-agricultural-expan...

Re: Perennial rice: Plant once, harvest again and again

#198

Post by thaumasiotes »

hosh wrote: post #71
twawaaay wrote: post #33

I know Chinese harvest their rice up to three times a year. I don't see how perennial rice could compete. Harvesting normal rice is just grabbing entire plants, as many as you can grab at a time. I may know nothing about how harvesting perennial rice is supposed to work, but I grew up as a farmer and I have imagination. You have to leave some part of the plant for it to keep growing crop which means you can't just gr…

According to this quote: > Perennial cultivars are strongly preferred by farmers; growing them saves 58.1% of labour and 49.2% of input costs in each regrowth cycle. In 2021, perennial rice was grown on 15,333 ha by 44,752 smallholder farmers in southern China. Seems like it makes sense to them. The increased labor in harvest is probably offset by the decrease in labor for planting.

>> In 2021, perennial rice was grown on 15,333 ha by 44,752 smallholder farmers in southern China.

> Seems like it makes sense to them.

...that's not the conclusion I would have drawn. 45,000 farmers and 60 square miles are both pitifully small numbers.

Re: Perennial rice: Plant once, harvest again and again

#199

Post by Maursault »

atleastoptimal wrote: post #43
chris_va wrote: post #18

(disclaimer that I manage a climate group, but not a rice expert) They touch on, but don't get into the details on one of the more interesting aspects of perennial rice. Rice fields are actually a huge emitter of methane. Depending on the accounting, they contribute as much to global warming as the aviation sector. The fields emit methane when flooded, the stagnant water gets oxygen depleted, and the biomass in the s…

Damn is there any commodity crop that isn't an environmental disaster?

Celery, cucumbers and mushrooms.[1] Celery is catabolic, but we could live on just cucumbers and mushrooms.

[1] https://www.vegetableclimate.com/climate-credentials/greenho...

Re: Perennial rice: Plant once, harvest again and again

#200

Post by maxerickson »

Maursault wrote: post #199
atleastoptimal wrote: post #43

Earlier quoted context omitted.

Damn is there any commodity crop that isn't an environmental disaster?

Celery, cucumbers and mushrooms.[1] Celery is catabolic, but we could live on just cucumbers and mushrooms. [1] https://www.vegetableclimate.com/climate-credentials/greenho...

Furiously making cucumber vinegar so you can pickle 10,000 cucumbers for the winter.
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