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I finally understand methane lifetimes

climateer.substack.com

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Re: I finally understand methane lifetimes

#81

Post by VintageCool »

FrenchAmerican wrote: post #80
dr_dshiv wrote: post #70

Earlier quoted context omitted.

Read their letter and paper. They don’t want to ban large scale deployments. They want to ban any deployments, even for small-scale research purposes. This will ensure that all unvalidated technologies remain untested. That’s unfortunate because we all know we can’t decarbonize in time. We need other braking mechanisms and we should be pretty open to experimentation. If no one is upset with your particular atmospheri…

"we all know we can’t decarbonize in time" I guess you mean "we all know that almost no current government has the political courage to do what is necessary so that we decarbonize in time". Or " we all know that we don't have the fortitude to do to do what is necessary so that we decarbonize in time". => that version is better if governments do what their public opinion is willing to do. To fight in the WWI and WII,…

I think you under-estimate how quickly human populations will mentally adjust to "the new normal" and how much suffering we're willing to tolerate, especially if it happens to someone else on the other side of the planet.

Re: I finally understand methane lifetimes

#82

Post by EricLeer »

cwkoss wrote: post #36

If I have a compost pile that's producing methane, is igniting that methane to convert it all into CO2 (regardless of getting any utility from that energy) effectively "net carbon negative" because CO2 has much less climate effect than methane? Kind of weird to think about how burning methane without capturing the energy could be better for the planet that letting it leak into the atmosphere naturally.

Yes, by the same mechanism burning waste also has a lower impact then letting it sit on a landfill (even excluding using the heat for something usefull like electricity production, or a heat network).

Re: I finally understand methane lifetimes

#83

Post by dr_dshiv »

FrenchAmerican wrote: post #80
dr_dshiv wrote: post #70

Earlier quoted context omitted.

Read their letter and paper. They don’t want to ban large scale deployments. They want to ban any deployments, even for small-scale research purposes. This will ensure that all unvalidated technologies remain untested. That’s unfortunate because we all know we can’t decarbonize in time. We need other braking mechanisms and we should be pretty open to experimentation. If no one is upset with your particular atmospheri…

"we all know we can’t decarbonize in time" I guess you mean "we all know that almost no current government has the political courage to do what is necessary so that we decarbonize in time". Or " we all know that we don't have the fortitude to do to do what is necessary so that we decarbonize in time". => that version is better if governments do what their public opinion is willing to do. To fight in the WWI and WII,…

I think we agree with each other. I’m not aware even of a plan that would enable timely decarbonization. If you know of one, I’d be interested to read it. But at present, the time targets are completely infeasible. That doesn’t mean amazing progress isn’t being made. For instance, Dubai will be 100% solar powered by 2050. But that’s not fast enough.

Let me know what you think of this article: https://www.nytimes.com/interactive/2022/04/25/magazine/vacl...

Re: I finally understand methane lifetimes

#84

Post by NumberWangMan »

s1artibartfast wrote: post #76
NumberWangMan wrote: post #72

Earlier quoted context omitted.

> The complicated part that I have spent many hours trying to understand is how more CO2 increases the greenhouse effect if the the frequencies it absorbs are already 100% absorbed. I'm curious where you're getting the figure that the relevant frequencies are 100% absorbed, I didn't think it was that high, but I'm far from an expert on this. I don't think you can ever get to 100%, just arbitrarily close -- there's al…

>I'm curious where you're getting the figure that the relevant frequencies are 100% absorbed, I didn't think it was that high, but I'm far from an expert on this. Last time I researched this I saw various estimates that IR in the CO2 absorptions bands only makes it 10-25 meters before it 99% of it is absorbed by CO2. Your link gives and average distance of 2.6m for IR in the CO2 absorption band. >Assume that [C]=400…

> Assume that [C]=400 ppm. The mean free path becomes 2.646m so that N=3024. The probability of returning to the Earth becomes p(1)=0.9997. A photon with frequency or wavenumber near the centre of the absorption band is virtually certain to make the return to Earth. If the CO2 concentration is doubled, the probability doesn’t change much; it becomes p(1)=0.9998. Any CO2 increase has minor effect on the photons in the center of the absorption band. This part of the band is ‘saturated’.

Ok, so as I'm thinking about this, and forgetting about the edges of the absorption bands -- in steady state, all the heat of the sun must be radiated out into space, otherwise the earth would be hot enough to have killed off all life millions of years ago.

When you think about it, an IR photon that returns to earth is not really done, it doesn't get "stuck" to the earth. The surface of the earth either reflects it back up, or absorbs it and its energy, and then re-emits it some time later. Even with 0.9997 probability of returning to earth, if you try enough times, you'll eventually escape, and photons get a lot of tries, really fast. That 0.0003 probability matters, and if you change it to 0.0002, it seems to me like it's a really, really big deal.

To take it the other way -- if any given IR photon had, say, a 50% chance of escaping the earth, my intuition says that it would let the earths temperature drop extremely drastically at night, like the moon or mercury. The sheer speed at which photons get "tries" to escape means that the greenhouse gas blanket has to absorb and send back almost all photons in order for the earth not to become icy every night.

Re: I finally understand methane lifetimes

#85

Post by SV_BubbleTime »

s1artibartfast wrote: post #77
SV_BubbleTime wrote: post #73

Earlier quoted context omitted.

I think that falls within his qualifier as “under our control”… and also previously tested. I have no dog in the fight, but be honest about what the argument really is.

I guess I don't understand the distinction. Why one is out of our control? Certainly we could stop injecting extra iron into the atmosphere just as easily and dismantling a solar plant. It seems like a lot of people conflate "out of control" with "I don't understand it".

Ok, releasing the iron compound into the sky we find causes immeasurable amounts of suffering. Go up there and get it back.

You know exactly what the topic is an you are pretending not to - for some reason.

Re: I finally understand methane lifetimes

#86

Post by isoprophlex »

quantum_magpie wrote: post #59
isoprophlex wrote: post #41

Earlier quoted context omitted.

Look at it this way: there's a finite amount of OH radicals being produced each interval of time, which reacts with some CH4 and disappears in the reaction. You are correct that OH radicals regenerate, but more methane => "breakdown capacity" becomes overwhelmed. This is known as zeroth order kinetics, similar to alcohol metabolism. Drinking 2 beers = 3 hours until sobriety; 4 beers = 6 hours. Your liver has a fixed…

There is no such thing as zero-order kinetics in atmospheric chemistry.

But are there pseudo zero order kinetics in atmospheric chemistry? smirks
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