[HN Gopher] I finally understand methane lifetimes
       ___________________________________________________________________
        
       I finally understand methane lifetimes
        
       Author : gk1
       Score  : 190 points
       Date   : 2022-04-29 12:32 UTC (10 hours ago)
        
 (HTM) web link (climateer.substack.com)
 (TXT) w3m dump (climateer.substack.com)
        
       | boringg wrote:
       | 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 policy makers otherwise it is far to
       | easy for mud-rakers to try and undo meaningful work/change in our
       | policy/business arenas. Abstract away the complications.
       | 
       | Great piece.
        
         | photochemsyn wrote:
         | 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 and CH4 in
         | the atmosphere. Hence we can think of water vapor in the
         | atmosphere as a _feedback_ to the CO2 /CH4 _forcing_.
         | 
         | This is not too difficult for people to understand. The fact
         | that methane is a reactive gas, i.e. CH4 + O2 -> CO2 over time
         | (OH just being an intermediate), means it gets converted to
         | CO2, accounting for the relatively short 10-year lifetime. CO2
         | + OH/O2 does nothing, so we can expect a longer lifetime. The
         | notion that CO2 lifetime in the atmosphere is 100 years is
         | perhaps a bit more complicated, as it involves ocean uptake and
         | things like that, but it's all fairly straightforward.
         | 
         | The gas/oil/coal sector might want people to believe that
         | passing gas in a closed room won't eventually create a stink,
         | but it's the same general concept.
        
           | alar44 wrote:
        
           | boringg wrote:
           | I agree I don't think it's that complicated but when you have
           | a regulatory industry surrounding complex science with
           | politicians weighing in it can get very tricky. I refer to
           | climate deniers/paid advocacy groups and mud rakers who
           | constantly try and trip up progress by trying to bring sow
           | doubt through poking holes in the argument or nitpicking
           | small issues.
        
           | s1artibartfast wrote:
           | >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.
        
           | lstodd wrote:
           | 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.
        
             | quantum_magpie wrote:
             | Albedo is included in every single atmospheric model.
        
         | nverno wrote:
         | I think it is the dumbing down that makes it easier for mud-
         | rakers. People know it's complicated anyway, and the average
         | person can grasp complicated things as well as you.
        
           | [deleted]
        
           | Enginerrrd wrote:
           | As an environmental engineer that deals with the interface
           | between the public and policy makers, I think I'm inclined to
           | agree with you. The public IS dumb, but every time they try
           | to dumb down the principles they regulate on, it always comes
           | at the detriment of the environment and the 'little guy'.
           | It's almost always better to delegate policy to smart
           | qualified people with correctly aligned interests. Getting
           | that latter part right is hard, but that is the job of a
           | competent public official.
        
             | boringg wrote:
             | It's a difficult place to be - damned if you do and damned
             | if you don't.
        
           | boringg wrote:
           | I disagree. There is an inherent risk that dumbing down or
           | abstracting away the complexities of the science to have an
           | appropriate discourse on appropriate policy action creates
           | blowback but trying to create a system that accounts for the
           | complexities of the science would just cause infinite
           | headaches.
           | 
           | The business mechanism to try and solve this needs to be
           | simple and relatively clear and should align with the
           | science. The general population doesn't have the time or
           | capabilities to understand the complexities. I am not saying
           | hide the complexity - I am just saying don't have it in the
           | forefront of the policy decisions - and don't constantly
           | change the regulatory mechanism unless it is grossly
           | misaligned with the science.
           | 
           | I am glad you think the average person has the same
           | capability to understand the problems and has taken
           | environmental science engineering programs - I feel much
           | better about that.
        
         | the8472 wrote:
         | You can't push it out in a single news blurb. But if it were
         | covered as some math/physics/chemistry sections building on
         | each other in secondary education it should be manageable.
         | Especially if you already covered exponential decays. Add the
         | secondary effect of the exponential decay parameter varying
         | based on concentration.
        
       | cwkoss wrote:
       | 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.
        
         | mikepurvis wrote:
         | I believe the answer is yes, but I imagine it would be far too
         | diffuse to actually achieve ignition. Same issue applies to
         | various schemes for putting a pilot light at cow's butts to
         | eliminate the "cow fart emissions" issues.
         | 
         | (Quite apart from the fact that it's belches not farts that are
         | the issue anyway, so the pilot light would be at the wrong
         | end...)
        
           | wardedVibe wrote:
           | Wait, are you telling me that we need fire breathing cows for
           | the good of the environment?
        
         | gruez wrote:
         | 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.
        
           | asciimike wrote:
           | 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.
        
             | [deleted]
        
         | s1artibartfast wrote:
         | The same is true for a lot of chemistry. There are tons of
         | compounds that are poisonous, but if you break down the
         | molecule, it is perfectly safe to eat.
        
       | bricemo wrote:
       | Beyond methane and climate change, this is a lovely step through
       | of simply grappling with a new concept to understand it, one
       | site/paper at a time. I wish I could teach my parents how to do
       | this, they never get beyond the first page
        
       | photochemsyn wrote:
       | Additional source describing the difference between CH4 and CO2
       | in the atmosphere:
       | 
       | > "Methane makes up just 0.00018 percent of the atmosphere,
       | compared to 0.039 percent for carbon dioxide. (CO2 is roughly 200
       | times more abundant.) Yet scientists attribute about one-sixth of
       | recent global warming to methane emissions; what methane lacks in
       | volume it makes up for in potency. Over a 20-year period, one ton
       | of methane has a global warming potential that is 84 to 87 times
       | greater than carbon dioxide. Over a century, that warming
       | potential is 28 to 36 times greater. The difference occurs
       | because methane is mostly scrubbed out of the air by chemical
       | reactions within about ten years, while carbon dioxide persists
       | in the atmosphere for much longer than a century."
       | 
       | https://earthobservatory.nasa.gov/features/MethaneMatters
       | 
       | A big uncertainty is the future of permafrost and shallow marine
       | sediments, which store carbon in various forms. Some scenarios
       | are, well, not good:
       | 
       | https://climatemodeling.science.energy.gov/presentations/imp...
       | 
       | > "Our simulations include a plausible release from clathrates in
       | the Arctic that increases global methane emissions by 22%, as
       | well as a scenario with 10 times those clathrate emissions. The
       | CESM model includes a fully interactive physical ocean... The
       | results indicate that such Arctic clathrate emissions (1)
       | increase global methane concentrations by an average of 38%, non-
       | uniformly; (2) increase surface ozone concentrations by around
       | 10% globally, and even more in polluted regions; (3) increase
       | methane lifetime by 13% ..."
       | 
       | It's kind of like defrosting a freezer full of 25,000 year old
       | fish guts...
        
       | ncmncm wrote:
       | This is very enlightening!
       | 
       | Key fact is how much methane is already there when your gout
       | entered matters a great deal, because its rate of clearance is
       | limited by how much hydroxyl radicals it can muster.
        
       | a_c wrote:
       | > never trust a number
       | 
       | One pet peeve of me is the water consumption of everything. Take
       | milk production for example, it disregards so many things, local
       | climate, soil conditions, ecology of having cow on land,
       | biodiversity and so on. Somehow milk production boils down to a
       | single number and is compared with e.g. almond milk. Almond milk
       | uses less water hence good.
       | 
       | At least we are way over the age of line of code..
        
         | colechristensen wrote:
         | Yup.
         | 
         | In Iowa we put porous pipes in the ground to drain rain into
         | the rivers faster because otherwise about half the state would
         | have standing water on the surface.
         | 
         | Water consumption of Iowa cows does not matter at all, water
         | consumption of a lot of cows doesn't matter at all. There is
         | very little irrigation in Iowa.
         | 
         | There are places where water is a limiting factor, and places
         | where it isn't.
        
       | sandworm101 wrote:
       | >> This has to be a typo, but it's yet another reminder that -
       | say it with me - you can never trust a number.
       | 
       | No. Never trust an answer to an overly-simplified question.
       | Asking for the lifetime of atmospheric methane is like asking
       | what temperature water boils at. When faced with an overly-
       | simplistic question an intelligent respondent will generally make
       | all sorts of assumptions. I assume he means at sea level. I
       | assume he means on planet earth. I assume he means normal not-
       | heavy water. Answer: 100c. This isn't about trusting answers in
       | the form of simple numbers. Ask an overly-simple question and
       | expect an overly-simple answer. The fault is with the asker.
        
         | s1artibartfast wrote:
         | It is clearly both. The correct answer to an overly simple
         | question is that it depends. If someone is stating an answer,
         | but leaving off the assumptions, they are doing a disservice
        
       | dr_dshiv wrote:
       | 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
       | atmosphere results in increased lifetimes of methane. The reason
       | carbon monoxide (CO) has three times the warming potential of CO2
       | is because CO uses OH, increasing methane!
       | 
       | So, why not produce a bunch of OH? Because OH has a half life of
       | less than a second. Hmm.
       | 
       | However, aerosolized plant terpenes (such as produced by
       | wetlands) are a natural source of OH in the atmosphere.
       | 
       | Interesting. Perhaps this should change the calculation of the
       | carbon credits due to terpene generating biomes (above and beyond
       | the carbon sequestered by the plants). Or, maybe we could mass
       | produce terpenes to clean out atmospheric methane (e.g., after a
       | pipeline leak or something).
       | 
       | Anyone know more?
        
         | ComputerGuru wrote:
         | The short lifespan of an OH radical isn't an issue if it's
         | deployed at the site of emission (a la scrubbers). You then
         | don't need them to last long enough to randomly bump into
         | methane particles in the wild as you're inducing them in a
         | high-methane concentration environment where you expect them to
         | react before they react with something else and break down.
         | 
         | That's the moral of the story for all climate control: don't
         | produce bad stuff, if you have to try to get rid of it as close
         | as possible (temporally and spatially) to the source because
         | once it's diluted in the atmosphere it becomes insanely more
         | difficult.
         | 
         | Global CO2 levels are at 450 parts per _million_ meaning you
         | need to actively filter 2,222 parts of air to get to one measly
         | CO2 molecule _in the wild_. It's horrible inefficient
         | (expensive and slow). But if you don't produce the CO2 or if
         | you tackle it right then and there at the site of production
         | where it is at much higher concentrations, you still have a
         | chance.
        
           | thaumasiotes wrote:
           | I remember someone pointing out that (1) there is a very
           | large amount of advocacy based around going to the Great
           | Pacific Garbage Patch and harvesting microplastic particles
           | there; and (2) this is a colossally stupid idea, because
           | there is almost no plastic in the Great Pacific Garbage
           | Patch. It's a a part of the ocean where the level of plastic
           | is higher than usual. But it's still a part of the ocean.
           | 
           | If you want to filter plastic out of the ocean, you want to
           | filter it out of the input stream, where it's concentrated,
           | not out of the end product of diluting the input stream with
           | the entire ocean.
           | 
           | Interestingly, the wikipedia article on the Patch is
           | headlined by a disclaiming of a very similar mistake:
           | 
           | > Despite the common public perception of the patch existing
           | as giant islands of floating garbage, its low density (4
           | particles per cubic metre (3.1/cu yd)) prevents detection by
           | satellite imagery, or even by casual boaters or divers in the
           | area.
           | 
           | https://en.wikipedia.org/wiki/Great_Pacific_garbage_patch
        
         | metacritic12 wrote:
         | > 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 the atmosphere to begin
         | with. In such a case OH is not truly being used up in any real
         | sense. It's whatever that generates OH is being used up, and
         | that can be artificially boosted.
        
           | conradev wrote:
           | One limiting factor in generating OH is specific wavelengths
           | of light, which is harder to artificially boost
        
             | dr_dshiv wrote:
             | Laser beams. We can only hope that this whole solution is
             | dependent on laser beams :)
        
           | s1artibartfast wrote:
           | "consumed" is better than "used up".
           | 
           | In that <1 second, the OH can react with methane or CO. The
           | more CO in the atmosphere, the more likely it will find the
           | OH before the methane.
           | 
           | It is like throwing breadcrumbs to ducks and geese. The more
           | ducks in the pond, the less crumbs the geese will get.
        
           | quantum_magpie wrote:
           | 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.
        
             | s1artibartfast wrote:
             | In this case, annual reaction mass of OH is more important
             | than the concentration at any given time. The concentration
             | of any highly reactive molecule will be very low, but that
             | doesn't tell you how much was created or consumed.
             | 
             | Methane levels don't impact OH levels (it is always
             | consumed immediately). OH generation levels can impact
             | methane levels. CO levels can compete with methane for OH
             | as is it generated.
        
           | isoprophlex wrote:
           | 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 capacity, so drinking
           | twice as much doesn't double the metabolic rate.
           | 
           | I'll add that you're also entirely correct: if there's some
           | long lived chemical that catalyzes OH formation, sending that
           | up instead might be a good remedy IMO. If there's no
           | collateral toxicity...
        
             | quantum_magpie wrote:
             | There is no such thing as zero-order kinetics in
             | atmospheric chemistry.
        
         | zackees wrote:
        
         | alexose wrote:
         | 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
        
           | quantum_magpie wrote:
           | Well they haven't tested any of their assumptions in the
           | field and their atmospheric chemistry cycle diagram has some
           | bullshit reaction mechanisms so it is pretty much shit.
           | 
           | Also the following statement surprisingly lacks any mention
           | of anything related to atmospheric or earth scientists:
           | 
           | >We seek funding for a world-first trial in Australian waters
           | under scientific supervision, in cooperation with the marine
           | biology community and with industries including insurance,
           | fishing, tourism, energy and shipping.
        
             | dr_dshiv wrote:
             | How much money is worth "wasting" to investigate new
             | possible solutions to global warming?
             | 
             | If you look at the "official" plans, they all rely on the
             | emergence of magical new technologies. So we'd better start
             | testing even the less promising approaches. Shotgun
             | strategies are needed.
             | 
             | Of course, at the moment, many are seeking to _ban research
             | science_ in this area because it is viewed as morally
             | dangerous [1].
             | 
             | [1] https://climateandcapitalism.com/2022/01/17/climate-
             | scientis...
        
               | quantum_magpie wrote:
               | In this case, I think people want to ban large-scale
               | deployments of untested, unvalidated technologies with no
               | definitive positive effect and a non-negligible
               | probability of disastrous consequences.
               | 
               | I myself am an atmospheric chemist and no one has banned
               | me from doing scientic research.
        
               | dr_dshiv wrote:
               | 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 atmospheric
               | research, maybe you aren't ambitious enough. Just
               | kidding-- I'd love to know what you are working on.
        
           | beders wrote:
           | 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?
        
             | s1artibartfast wrote:
             | you could say the same about anything. Installing solar or
             | wind power isn't natural part of the environment, and
             | "something" could go wrong, better not do that either.
        
             | rootusrootus wrote:
             | Seems like we've come far enough to understand that doing
             | nothing and conserving our way out of this problem isn't
             | viable. The time for engineering is upon us.
        
             | jxramos wrote:
             | 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.
        
         | tejohnso wrote:
         | > the CO2 produced by methane is not counted toward methane's
         | overall climate impact
         | 
         | It definitely is in some contexts. It's often cited in CO2
         | equivalent over time. Methane start off to be something like 80
         | times more potent as a greenhouse gas than CO2. Then as it
         | decays to CO2 its impact is that of CO2 but time has to be
         | accounted for. So for every ton of methane, you can estimate an
         | equivalent CO2 tonnage over then next, say, 50 years.
         | 
         | A quick search for methane co2 equivalent reveals a site
         | claiming methane has 25 times more global warming potential
         | than CO2 over 100 years.
        
           | dr_dshiv wrote:
           | Here is a source explaining why the CO2 produced by methane
           | isn't counted in estimates of global warming potential. It
           | seems to come down to the different calculations required for
           | anthropogenic sources.
           | 
           | https://ghginstitute.org/2010/07/13/what-is-different-
           | about-...
        
       | paultgriffiths wrote:
       | Very interesting, and a great description of methane self-
       | feedback.
       | 
       | The perturbation lifetime analysis - the idea that the time
       | constant of the atmospheric response to methane is longer than
       | the time constant of the reaction that removes methane - comes
       | from a beautiful paper by Michael Prather that may be of interest
       | to anyone with some linear algebra. See
       | https://unfccc.int/files/meetings/workshops/other_meetings/a....
        
       | Robotbeat wrote:
       | 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 reaches of the atmosphere.
       | Does it keep going? What stops it from getting to the
       | thermosphere and (ultimately) exosphere?
        
         | masklinn wrote:
         | > 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 GWP of ~80 over 20 years,
         | ~30 over 100 years, but is still around 7 over _500 years_ ,
         | despite a lifetime of only 12 years.
        
           | Robotbeat wrote:
           | What about the H2O?
        
           | snewman wrote:
           | [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.
        
       | dexwiz wrote:
       | Half lives are a poor term for this; you are really looking for
       | reaction rates, which are dynamic systems. Methane doesn't just
       | disappear, it reacts with something else. A radioactive isotope's
       | decay is relatively self contained, so the half life terminology
       | holds.
       | 
       | A microgram or a kilogram of U-235 will decay at about the same
       | rate, making half life a useful number. Methane reacts with OH,
       | which is sourced from different places. Upper levels of the
       | atmosphere get more UV light, which produces all sorts of
       | radicals to react with. But there are also biological and
       | geological sources for radicals which also contribute to
       | reactions. Sum these reactions together and you get something
       | that can be approximated with a half life, but this assumes
       | constant input of reactants. As we increase our output of Methane
       | this changes the reaction rates in the atmosphere and that half
       | life number changes.
        
         | ComputerGuru wrote:
         | AP Chemistry: the year I took it was the first (only?) year a
         | free response question didn't feature reaction rates. I learned
         | my lesson on the risks of studying to the historic exam
         | contents!
        
       | Melatonic wrote:
       | Don't forget about those deep ocean Methane Clathrates !
        
       | rob_c wrote:
       | As a self professed what? Ive read pop-sci books with more graphs
       | and equations over breakfast.
       | 
       | Why is there this celebration of mediocrity in dealing with
       | equations and instead citing percentages.
        
       | philipov wrote:
       | I finally understand methane _lifeforms_...
        
       | wrycoder wrote:
       | tl;dr
       | 
       | > _I finally have some confidence that I understand how methane
       | lifetimes work, and that for my purposes it can be summarized as:
       | 
       | Methane emissions decay gradually, with an average lifetime of
       | about 12 years ("perturbation lifetime", which is what matters
       | for climate purposes).
       | 
       | This will increase by roughly 35% if methane concentrations
       | double, or decrease roughly 25% if concentrations return to pre-
       | industrial levels._
        
         | amateurICEguy wrote:
         | (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
         | concentrations of methane that are present in the atmosphere.
         | Sure, OH is rare, but I'd guess is generated in large amounts
         | in the upper atmosphere (UV + H2O -> OH- + O+ + momentum to
         | keep them away from each other).
         | 
         | Does anyone here have any hard math on this?
        
           | twic wrote:
           | FWIW, and this is a rather minor and pedantic point, these
           | are hydroxyl radicals, not hydroxide ions, so it's:
           | 
           | H2O + g -> OH* + H*
           | 
           | Rather than:
           | 
           | H2O + g -> OH- + H+
           | 
           | Oh, and whichever way, H2O splits into OH and H, not OH and
           | O, but i assume that was a typo!
        
             | robocat wrote:
             | > 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 <sup>*</sup>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.
        
         | thatcherc wrote:
         | > This will increase by roughly 35% ...
         | 
         | I was a bit confused by this sentence (which is a direct
         | excerpt from the piece). Reading the whole article, the `this`
         | refers to the methane lifetime. Oddly (to me), the lifetime
         | methane in the atmosphere increases with the amount of methane
         | in the atmosphere. That's what the author has been working to
         | understand. Very interesting!
        
           | rocqua wrote:
           | It makes sense, if you take into account that, apparently,
           | absorbing methane from the atmosphere depletes the
           | atmosphere's capacity for absorbing methane. Hence the more
           | methane that exists, the more methane is getting absorbed,
           | the less capable the atmosphere is at absorbing methane.
        
             | scratcheee wrote:
             | Yeah, and to simplify further, the atmosphere's got a fixed
             | amount of methane-removing capability, and as we exceed
             | this capability it can't absorb methane any faster, so the
             | ratio of methane that gets absorbed starts dropping even
             | though the amount being absorbed doesn't drop.
             | 
             | The reality is more complicated because the cut off is very
             | blurry - absorbsion does still increase as methane
             | increases, just not fast enough to keep up, and it falls
             | further behind the more methane we put out.
        
             | mudita wrote:
             | Which to me raises the question: Are there any
             | possibilities to increase the absorption of methane
             | somehow?
             | 
             | And it seems like there are methods for capturing methane:
             | https://news.mit.edu/2022/dirt-cheap-solution-common-clay-
             | ma...
        
             | washadjeffmad wrote:
             | If I'm thinking clearly, using "absorbing" here implies
             | that atmospheric concentrations of methane have an effect
             | on the amount of methane that can be released. A lower
             | absorption would then be "good" because it would slow the
             | rate of accumulation of methane in the atmosphere.
             | 
             | The opposite is true, that the higher the methane
             | concentration, the lower the rate of effect would be to
             | degrade all atmospheric methane. The rates of methane
             | accumulation and its degradation are inversely proportional
             | beyond the limit of the atmosphere to degrade it.
        
       | agluszak wrote:
       | The next step would be understanding Rust lifetimes ;)
        
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