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The Methane Thread pt. 2

Re: The Methane Thread pt. 2

Unread postby Plantagenet » Wed 23 Dec 2015, 18:42:01

ritter wrote:
Plantagenet wrote:Giant hole in Arctic Ocean Sea ice created by new methane plume?

Prolly just Santa Claus. :-D


Are you suggesting that Santa has gas?

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Re: The Methane Thread pt. 2

Unread postby onlooker » Fri 08 Jan 2016, 11:18:45

Another increasing source of methane emissions. Northern Lakes. http://www.su.se/english/about/profile- ... s-1.263259
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Re: The Methane Thread pt. 2

Unread postby dohboi » Sun 10 Jan 2016, 04:23:09

Scientists say we could be underestimating Arctic methane emissions

https://www.adn.com/article/20151222/ba ... -emissions
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Re: The Methane Thread pt. 2

Unread postby Tanada » Sun 10 Jan 2016, 09:13:39

The problem with estimates as I see it is the atmospheric levels do not support the idea we are emitting substantially more. The atmosphere has a clearance rate that removes methane molecules in well under 100 years. In fact the science seems to indicate it has a half life of just 7 years, so each seven years the quantity is cut by half. 100 percent + 7 years is 50 percent +7 years is 25 percent + 7 years is 12.5 percent. In other words the methane released today will be 7/8ths oxidized when a baby born today can legally drink in the USA.

For the rate of emissions to be substantially higher than prior estimates and for current levels to be where they are the natural clearance rate would have to be even faster than it already is. However scientists have been studying methane clearance for several decades now at minimum, you would expect someone in the last 20-30 years to have noticed if all the clearance rate estimates are off by a substantial amount.
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Re: The Methane Thread pt. 2

Unread postby ozcad » Sun 10 Jan 2016, 10:56:20

Superman will have to relocate his ice palace.
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Re: The Methane Thread pt. 2

Unread postby onlooker » Sun 10 Jan 2016, 11:00:58

ozcad wrote:Superman will have to relocate his ice palace.

Maybe Superman will have to go to Pluto or something :-D 8)
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Re: The Methane Thread pt. 2

Unread postby dohboi » Sun 10 Jan 2016, 16:31:11

T, many good points.

But the flip side of that is, given the relatively short half life of methane, doesn't that mean that, just to sustain the historically very high levels of atmospheric methane we now see (up ~150% versus ~40% for CO2), there must currently be very large and ongoing increases in methane emissions far beyond all previous periods (going back at least hundreds of thousands of years)?
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Re: The Methane Thread pt. 2

Unread postby Tanada » Sun 10 Jan 2016, 17:46:02

dohboi wrote:T, many good points.

But the flip side of that is, given the relatively short half life of methane, doesn't that mean that, just to sustain the historically very high levels of atmospheric methane we now see (up ~150% versus ~40% for CO2), there must currently be very large and ongoing increases in methane emissions far beyond all previous periods (going back at least hundreds of thousands of years)?


Sure as far as you go, but take a look at this composite graph.
Image

If you check the side of the Methane plot you will see it is counted in parts per billion by volume, so to translate into CO2 like numbers you have to divide the figures by 1,000. IOW in about 1983 when they started doing continuing monitoring we had around 1.63 ppmv Methane in the atmosphere. It then increased to about 1.75 ppmv in 1996 and hung out close to that level until 2007 when drilling really started to pick up world wide because of the high oil prices. We have been sloping up from there until now and are around 1.825 ppmv moving average now.

Remember Methane enters the air at 100 percent and declines by 50 percent every seven years, so every year you have to release 7 percent of the world atmospheric methane total just to replace what has been oxidized in the prior 12 months. If you manage to do that the number is stable, and to make the total grow you have to release 8, 10, 20 percent of the world atmospheric total all in less than a year.

Second thing to remember, say you use the 10 year number for Methane amplification compared to CO2. This is reasonable because the half life is so short after 10 years about 65 percent of the release has oxidized. So with a CO2e of 95 after ten years that 1.825 ppmv CH4 is about as much warming as adding another 173 ppmv CO2 into the atmosphere. However the change from 1.63 to 1.825 in equivalents is the difference between 173-155=18 ppmv CO2e rise over the period from 1983-2015 aka 0.56 ppmv CO2e per year. It is nothing to celebrate, but it is not nearly as scary as the fear mongers would have you believe compared to the increase of 2.0 ppmv of CO2 that stays in the atmosphere for millennia. Unless the clathrate gun really does go off in a big way the atmospheric clearance rate for CH4 will be able to keep up and sustain the atmospheric levels low enough that it is an asterisk, not the main forcing agent.
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Re: The Methane Thread pt. 2

Unread postby dissident » Sun 10 Jan 2016, 18:21:23

It is unfortunate that the risk of CH4 release from the shallow Siberian shelf has not been quantified any better than 5 years ago. They have done some more ship cruises but no systematic coring to map the dissociated CH4 reservoir. There really is no excuse for this since the seabed is less than 60 m below the surface and it is a well established technology.
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Re: The Methane Thread pt. 2

Unread postby dohboi » Sun 10 Jan 2016, 20:27:47

T, yes, the entire quantity of atmospheric methane must be replaced every 7 years to just stay stable. We (now with the help of melting permafrost and clathrates) are producing enough more than enough to do that on a continual basis. I don't find that comforting.

But yes, if we could find ourselves a way to stop our emission, our part of that extra methane would fairly quickly go away, and we could only pray that it would not be taken up by the methane feedbacks that already seem to be kicking in. Unfortunately, we have turned heavily toward NG production, and it is proving to be very hard not to let a good portion of that escape directly into the atmosphere (seen most dramatically in CA right now, but it is a chronic issue throughout the industry, afaics. And then there are little things like rice growing, and cattle and sheep raising the latter two of which no one around here seems to want to take very seriously.

But thinking about all of this prompted some questions in my brain that I don't know the answers to right off:

One thing saving us from the full impact of super high atmospheric CO2 concentrations is its absorption into the oceans. Does anyone know how much this is also a factor with methane? Does atmospheric methane dissolve in water easily? What portion (if any) of our emissions of methane are being absorbed by oceans? When (and if) absorbed, does it form an acid, like CO2 does?

I can't recall reading anything about this either way (and I'm too damn lazy right now to look up the chemistry myself :oops: ).
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Re: The Methane Thread pt. 2

Unread postby onlooker » Sun 10 Jan 2016, 20:56:08

Speaking of questions about Methane, what about the fact that Oil companies and others have stated their intention to do deep sea drilling to use precisely methane as a energy source. Would that not stand the chance of creating conditions for massive dislocation of said Methane and in fact the Clathrate Gun going off?
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Re: The Methane Thread pt. 2

Unread postby Tanada » Mon 11 Jan 2016, 10:59:30

dohboi wrote:T, yes, the entire quantity of atmospheric methane must be replaced every 7 years to just stay stable. We (now with the help of melting permafrost and clathrates) are producing enough more than enough to do that on a continual basis. I don't find that comforting.

But yes, if we could find ourselves a way to stop our emission, our part of that extra methane would fairly quickly go away, and we could only pray that it would not be taken up by the methane feedbacks that already seem to be kicking in. Unfortunately, we have turned heavily toward NG production, and it is proving to be very hard not to let a good portion of that escape directly into the atmosphere (seen most dramatically in CA right now, but it is a chronic issue throughout the industry, afaics. And then there are little things like rice growing, and cattle and sheep raising the latter two of which no one around here seems to want to take very seriously.

But thinking about all of this prompted some questions in my brain that I don't know the answers to right off:

One thing saving us from the full impact of super high atmospheric CO2 concentrations is its absorption into the oceans. Does anyone know how much this is also a factor with methane? Does atmospheric methane dissolve in water easily? What portion (if any) of our emissions of methane are being absorbed by oceans? When (and if) absorbed, does it form an acid, like CO2 does?

I can't recall reading anything about this either way (and I'm too damn lazy right now to look up the chemistry myself :oops: ).


While both CH4 and CO2 are 'well mixed gasses' in the average atmosphere CO2 is moderately heavier than O2 and N2 so as it crosses bodies of water it is easy for it to 'touch' the water surface. The surface layer is also a well mixed fluid, and that means if the CO2 level in the water is lower than it is in the air touching it some of the CO2 will diffuse across the interface as the two fluid average concentrations attempt to equaliberate. IOW if there is more CO2 in the air than the water the gas will be absorbed by the water, if there is more CO2 in the water than the air the gas will be expelled into the air. When you talk about CH4 on the other hand the gas is much lighter than O2 or N2. This causes methane to slowly rise on average through the air all the way up to the Ozone layer if it lasts long enough. This is also true in the water, the CH4 slowly rises to the surface of the water where it gets expelled into the air to continue its slow rise. If you have access to a school science lab like we had when I was growing up there were Natural Gas taps on ever lab station so you could set up a Bunsen Burner if needed for your lab work.
Image
Every year some students would figure out that using the tap to fill party balloons made them float, not as good as Helium but good enough to hit the lab ceiling or float away outside.

Now as a side note on your Vegan propaganda. The methane belched out by cattle and sheep is in no way or even scale different than the methane belched out by the buffalo and bison and antelope and deer and elephants and giraffes and yak and gorilla that eat a high fiber diet. The only reason this trope gets pushed so hard is humans are omnivores by nature of our digestive system and Vegans find this fundamental fact of life offensive. Sorry, not buying it. If you all want to live a Vegan lifestyle by choice more power to you, however a lifetime of food experiments have proven to me that a well rounded diet with a mix of food types is the healthiest and easiest to maintain.
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Re: The Methane Thread pt. 2

Unread postby dohboi » Mon 11 Jan 2016, 11:28:11

Sooo, basically you don't think it is likely that methane will be in touch with water enough to get dissolved in it, but you don't have anything on whether, when it does come in contact, it would dissolve and to what extent.

If free methane rises so easily in the atmosphere, then most of it would end up in the stratosphere and there eventually turn to CO2 and H20, both also ghgs. That is not a good thing either, of course. How much do we know about how fast the chemical make up of the stratosphere is changing?

I'll just point out on livestock methane/GW that, while I have seen a range of figures, I see no reputable study that places their contributions at zero. So basically you are putting your casual WAG up against every careful study that has been conducted on the subject. Sorry, I'll go with the carefully conducted studies.

It is a good lesson on how, even very intelligent and otherwise intellectually honest people will cherry pick facts to rationalize their own behavior. So, thank for that little (disturbing) lesson in psychology. :-D
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Re: The Methane Thread pt. 2

Unread postby Tanada » Mon 11 Jan 2016, 12:12:17

dohboi wrote:Sooo, basically you don't think it is likely that methane will be in touch with water enough to get dissolved in it, but you don't have anything on whether, when it does come in contact, it would dissolve and to what extent.

If free methane rises so easily in the atmosphere, then most of it would end up in the stratosphere and there eventually turn to CO2 and H20, both also ghgs. That is not a good thing either, of course. How much do we know about how fast the chemical make up of the stratosphere is changing?


It is not that the methane is not in contact with the water, for most land water supplies like lakes and reservoirs and rice paddies and swamps the methane concentration in the water is higher than the concentration in the air, so the gas tends to flow out of the water and up into the air. For the oceans and seas the picture is much more complex, some like the Black Sea are so filled with organic decay they are anoxic below the surface layer that exchanges gasses directly with the air. In the shallow waters near land there are a lot of methane generating decay processes taking place, and in deeper water there are methane seeps that add CH4 to the deeper ocean. Then there are the many places where the temperature is low enough and the pressure is high enough to generate methane Clathrates in a layer under the sea bottom ooze and mud that act as traps for the methane seeps. The more deeply you look into it the more exceptions you find to any general rule you try to create to describe what is going on in the oceans. Last but not least you have the bubbling methane gasses rising from the shelf delta fans of the Siberian rivers dumping into the Arctic Ocean. Nobody knows how long they have been releasing CH4 bubble plumes, how large the plumes are as a contribution to the total atmosphere or as Dissident pointed out even how extensive the clathrate formations on the shallow arctic continental shelf is.

For item two, the Methane is a well mixed gas in the atmosphere, in general it doesn't just shoot straight up into the Stratosphere. It swirls around rising or sinking with the air column it is a part of just like the rest of the air until either it runs into an OH radical that breaks it down into a CH3 radical plus water vapor H2O. Once it becomes a CH3 molecule it carries an electrical imbalance that allows it to easily react to O2 the next time it collides and the decay process proceeds fairly rapidly from there to CO2 and (2)H2O. If the CH4 molecule manages to avoid OH radicals until it crosses the cold trap at the boundary between the Troposphere and Stratosphere it is no longer subject to down drafts as we think of them and rises until it enters the Ozone layer where the O3 molecules act like an OH radical and easily break the CH4 into CO2 (2)H2O consuming Ozone in the process. Fortunately ozone at those altitudes is naturally produced by ultraviolet sunlight so it takes a LOT of chemical input to create an ozone hole faster than the sun can generate replacement ozone. The Arctic and Antarctic ozone problems arose because there are periods of months when no direct sunlight is present and ozone breakdown chemicals accumulate because in the cold and dark there is no initiating energy to start the chemical reaction. When the sun rises for the polar spring the sunlight sets off a lot of delayed chemical reactions breaking down a large portion of the ozone very quickly. Once all the reactive chemicals are 'used up' the sunlight starts rebuilding ozone faster than it is breaking down, but depending on the chemical load this might not replace all the ozone lost in the spring reaction period. This process created the infamous ozone hole over Antarctica and caused it to expand for many years before ozone depleting chemical controls reversed the process. The hole is still there but now it shrinks a little each summer instead of continuing to grow.

The fear about the Clathrate Gun hypothesis is that so much methane might be released in one burst that it would use up all the OH radicals in the air and then rise into the Stratosphere where it would use up all the Ozone as well and still have Methane left over in the atmosphere. This would have three effects, it would allow much more Ultraviolet sunlight to reach the surface. Secondly it would remove the Ozone greenhouse effect. Third it would add a large Methane greenhouse effect that would take many years to dissipate. Sunlight would continue to generate Ozone over the sunlit face of the earth, but depending on how much methane was released the ozone would be constantly broken down breaking down the CH4. It could take decades or even centuries to work through the methane excess depending on how big the release was initially and if the release continued for a long time the problem would continue as well.
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Re: The Methane Thread pt. 2

Unread postby dohboi » Mon 11 Jan 2016, 12:33:25

Thanks, I hadn't thought much before about the effect on the ozone layer of massive quantities of methane entering it.

The other thing that happens with large influxes of methane is that, at first, it's global warming potential goes up substantially:

... if global methane emissions were to increase by factors of 2.5 and 5.2 above current emissions, the indirect contributions to RF [radiative forcing] would be about 250% and 400%, respectively, of the RF that can be attributed to directly emitted methane alone.

Assuming several hypothetical scenarios of CH4 release associated with permafrost thaw, shallow marine hydrate degassing, and submarine landslides, we find a strong positive feedback on RF through atmospheric chemistry.

In particular, the impact of CH4 is enhanced through increase of its lifetime, and of atmospheric abundances of ozone, stratospheric water vapor, and CO2 as a result of atmospheric chemical processes


https://darchive.mblwhoilibrary.org/bit ... sequence=1

As the above article suggests, the effect an increase in methane-generated CO2 and water vapor in the stratosphere will have on GW could be substantial.

Right now, there is very little of either ghg there.

It will be like essentially 'adding one more blanket layer on the bed' so to speak.
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Re: The Methane Thread pt. 2

Unread postby Synapsid » Mon 11 Jan 2016, 18:45:44

dohboi, Tanada,

CO2 is about 70 times as soluble in water at 20C as methane is. Methane just dissolves, like oxygen does; CO2 reacts chemically with the water so the solution process is more interesting (and will be left for the reader.)

The Black Sea is indeed anoxic below the surface layers, and anoxic means loaded with hydrogen sulfide. No decay goes on there (decay needs oxygen), and future palaeontologists will find that the black shales which the seafloor sediments have become are loaded with exquisitely preserved fossils.

I'm guessing that ruminant herbivores emit more methane per kilo of food than non-ruminant ones do, but that's a guess. The rumen is a great organic lab.
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Re: The Methane Thread pt. 2

Unread postby dohboi » Mon 11 Jan 2016, 18:59:32

So elephants and gorillas should not have been on his list?

Thanks for the chemical distinctions.
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Re: The Methane Thread pt. 2

Unread postby Synapsid » Mon 11 Jan 2016, 19:05:22

dohboi,

I don't know. I'd check the numbers, which (coff, coff) I didn't do.
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Re: The Methane Thread pt. 2

Unread postby Subjectivist » Mon 11 Jan 2016, 20:13:32

Alongside the theory "girls don't poop," mankind once perpetuated a similar myth about the graceful mammals that bounce across Australia's grassy plains:

Kangaroos don't fart.

These beasts were once the mystery of the animal kingdom -- thought to produce low-methane, environmentally friendly toots.

However, new research on kangaroo crop dusting suggests this isn't true.

Methane — which is created naturally by gut bacteria inside animals digesting grasses and leaves — is a greenhouse gas that actively traps heat, contributing to global warming.

In the 1970s and 1980s, research suggested kangaroos don't produce much of the gas due to low-methane-producing bacteria called "Archaea" living in their guts.

At the time, scientists thought there might be a way to introduce these bacteria to cows, which produce high-methane flatulence, and reduce methane emissions on a global scale.

"The idea that kangaroos have unique gut microbes has been floating around for some time and a great deal of research has gone into discovering these apparently unique microbes," Adam Munn from the University of Wollongong in Australia said in a news release.

Alas, new research — studies that involved locking kangaroos in chambers to eat and fart blissfully and uninterrupted — show that kangaroos produce about the same amount of methane as animals similar in size.

They don't, however, fart as much as cows, which are capable of producing up to 200 liters of methane every day.

"Kangaroos are not mysteriously low methane-producing creatures, but herbivores with an active methane-producing microbe community', said Marcus Clauss from the University of Zurich, Switzerland.


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Re: The Methane Thread pt. 2

Unread postby dohboi » Mon 11 Jan 2016, 22:37:15

Yes, folks, here on the eviro threads of POForums discuss everything under (and sometimes beyond) the sun, including...kangaroo farts! :lol: :lol: :lol:

Thanks for the info. I'll wait till my drinking buddies are good and drunk before I spring this pearl of knowledge on them! :)
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