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I finally understand methane lifetimes

climateer.substack.com

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Re: I finally understand methane lifetimes

#51

Post by lstodd »

photochemsyn wrote: post #22
boringg wrote: post #16

It's this level of understanding that can't be pushed out to the general population. It is far too complicated for people to grasp. Add on to these complexities is that if we are trying to price carbon - the impacts change with the concentrations in the atmosphere. The market needs to be dumbed down to simplistic values (which thankfully they have) so that we have a sense on where to target and incentivize change for…

I don't think it's that complicated. Start with water vapor - moisture evaporates from the ocean, lakes, soil, vegetation. On average such a water molecule stays in the atmosphere for 4-10 days - because water condenses as rain, unlike methane or carbon dioxide. Water vapor increase accounts for about 2/3 of the immediate global warming effect, but is controlled by temperature, which is in turn controlled by the CO2…

You forgot the albedo effect of the clouds. On both sides - top and bottom. This has not ever been modelled to my knowledge. And it is very complicated.

Re: I finally understand methane lifetimes

#52

Post by asciimike »

gruez wrote: post #39
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.

Yep. It's also the same idea why we have gas flares on oil wells. It might look like it's oil companies setting stuff on fire for no reason, but it's better than just letting it leak.

Throwing that natural gas through a generator and an exhaust system is even better (more "net negative"). Compared to flaring, you can achieve a ~98% methane reduction and a ~60% CO2e reduction (source: https://www.crusoeenergy.com/digital-flare-mitigation).

Disclosure: I work for Crusoe Energy, who's goal is to eliminate routine flaring and align the future of computing with the future of the climate. We colocate data centers serving crypto miners and a high performance GPU cloud (crusoecloud.com). Our GPUs are indeed "carbon reducing", offsetting the emissions of a car over the course of a year.

Re: I finally understand methane lifetimes

#53

Post by snewman »

masklinn wrote: post #19
Robotbeat wrote: post #18

Another question I had: what does methane become once it breaks down? It becomes CO2 (a relatively minor greenhouse gas per unit weight, but long-lived) and H2O, right? H2O is no big problem in the lower troposphere. It just rains out. But in the stratosphere… it can stick around for much longer and impact the climate. How much does this matter for methane? I would imagine methane floats up pretty high into the upper…

> It becomes CO2 (a relatively minor greenhouse gas per unit weight, but long-lived) Although it should be noted that 1 tonne methane decays into around 2.5 tonnes of CO2 (I don't remember the exact number but it's around that) and GWP is measured by weight. So even after it's decayed, methane has a higher GWP than CO2. Which is why its GWP remains much higher than CO2 even over extremely long periods: methane has a…

[OP here] thank you! I see those ratios for 20 vs. 100 years everywhere, but I've never been able to put together a mental model that explains them. You've supplied the missing piece.

Re: I finally understand methane lifetimes

#54

Post by robocat »

twic wrote: post #13
amateurICEguy wrote: post #6

Earlier quoted context omitted.

(Physicist/Engineer of sorts here. Zero atmosphere knowledge) That half life depends on concentration is not surprising to me; ethanol's half life in the blood also depends on it's concentration and the reason is rather straight forward: the liver has limited amounts of enzymes needed to process booze. What is surprising to me, though, is that there is a mechanism that has such a massive effect at the extremely low c…

FWIW, and this is a rather minor and pedantic point, these are hydroxyl radicals, not hydroxide ions, so it's: H2O + γ -> OH• + H• Rather than: H2O + γ -> OH- + H+ Oh, and whichever way, H2O splits into OH and H, not OH and O, but i assume that was a typo!

> OH•

https://en.wikipedia.org/wiki/Hydroxyl_radical “Notation: The unpaired electron of the hydroxyl radical is officially represented by a middle dot, •, beside the O.”

Note that article uses a superscripted dot •OH, and the dot is usually prefixed in the article (presumably so as to put the dot next to the O that doesn’t have a full shell?).

However the article sometimes suffixes the dot, to put it beside the R organic radical. Weird.

Re: I finally understand methane lifetimes

#55

Post by jxramos »

beders wrote: post #34
alexose wrote: post #21

Earlier quoted context omitted.

There's a group that is advocating for spraying an Iron Salt Aerosol into the atmosphere, which apparently catalyzes the natural decomposition process. I haven't done a deep dive into the subject, but on the surface it seems pretty compelling. https://ironsaltaerosol.com/home/isa_summary

what could possibly go wrong? Let's put iron chloride where it doesn't belong, outside of our control. Haven't we done enough harm yet?

it's interesting folks have interpreted this as a blocking call to effectively do nothing in the face of such uncertainty. To me it was an invitation to begin to engage in second order thinking.

Re: I finally understand methane lifetimes

#57

Post by s1artibartfast »

photochemsyn wrote: post #22
boringg wrote: post #16

It's this level of understanding that can't be pushed out to the general population. It is far too complicated for people to grasp. Add on to these complexities is that if we are trying to price carbon - the impacts change with the concentrations in the atmosphere. The market needs to be dumbed down to simplistic values (which thankfully they have) so that we have a sense on where to target and incentivize change for…

I don't think it's that complicated. Start with water vapor - moisture evaporates from the ocean, lakes, soil, vegetation. On average such a water molecule stays in the atmosphere for 4-10 days - because water condenses as rain, unlike methane or carbon dioxide. Water vapor increase accounts for about 2/3 of the immediate global warming effect, but is controlled by temperature, which is in turn controlled by the CO2…

>I don't think it's that complicated

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.

If current CO2 PPM absorbs 100% of the IR it can interact with, why does X+1 PPM have positive forcing? The feedback loop is already maxed out?

If I shine a flashlight at a concrete wall, it doesn't matter if I make the wall thicker.

Re: I finally understand methane lifetimes

#58

Post by quantum_magpie »

metacritic12 wrote: post #33
dr_dshiv wrote: post #8

So, hydroxide radicals (OH) break down methane (CH4) into carbon dioxide (CO2). This is a good thing for the climate, as a molecule of methane has a much bigger warming effect than CO2. (Although it is odd that the CO2 produced by methane is not counted toward methane’s overall climate impact). There is limited OH in the atmosphere. As a result, more methane “uses up” the OH. That means that increased methane in the…

> There is limited OH in the atmosphere. As a result, more methane “uses up” the OH. > So, why not produce a bunch of OH? Because OH has a half life of less than a second. Hmm. These two statements seem to contradict? If the chemokinetics of OH generation is less than a second, then how can it be used up in the atmosphere? Assuming the <1 second kinetic is correct, there must be a dynamic equilibrium producing it in…

It's because that statement is incredibly wrong. Methane concentrations in atmosphere are 8 orders of magnitude higher than OH. More methane in the atmosphere has exactly 0 effect on OH. And you can't inject OH into atmosphere either because it will react with pretty much anything it comes in contact with.

Re: I finally understand methane lifetimes

#59

Post by quantum_magpie »

isoprophlex wrote: post #41
metacritic12 wrote: post #33

Earlier quoted context omitted.

> There is limited OH in the atmosphere. As a result, more methane “uses up” the OH. > So, why not produce a bunch of OH? Because OH has a half life of less than a second. Hmm. These two statements seem to contradict? If the chemokinetics of OH generation is less than a second, then how can it be used up in the atmosphere? Assuming the <1 second kinetic is correct, there must be a dynamic equilibrium producing it in…

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.

Re: I finally understand methane lifetimes

#60

Post by dr_dshiv »

conradev wrote: post #37
metacritic12 wrote: post #33

Earlier quoted context omitted.

> There is limited OH in the atmosphere. As a result, more methane “uses up” the OH. > So, why not produce a bunch of OH? Because OH has a half life of less than a second. Hmm. These two statements seem to contradict? If the chemokinetics of OH generation is less than a second, then how can it be used up in the atmosphere? Assuming the <1 second kinetic is correct, there must be a dynamic equilibrium producing it in…

One limiting factor in generating OH is specific wavelengths of light, which is harder to artificially boost

Laser beams. We can only hope that this whole solution is dependent on laser beams :)
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