[we received two articles on the same subject today from guest authors. each has its own merits-cr]
Guest Essay by Kip Hansen – 10 Feb 2022
I don’t want to alarm readers but the news is so shocking that I must. The concentration of atmospheric methane, a carbon-based molecule, is soaring; it is spiking; it is accelerating. Methane is a Greenhouse Gas! Well-mixed methane concentrations in the atmosphere have jumped from 1640 ppb to over 1900 ppb since the early 1980s.
The National Oceanic and Atmospheric Administration (NOAA) publishes the frightening graphic:
Luckily for us:
Scientists raise alarm over ‘dangerously fast’ growth in atmospheric methane
Our ever benevolent and protective scientist class has come to our rescue by raising the alarm – if they didn’t, we might not be adequately alarmed by this dangerous situation.
Seriously, the Nature punchline is, as you may have already guessed: “some researchers fear that global warming itself is behind the rapid rise.”
Yes, that’s right. Global Warming (itself!) may be behind the rapid rise.
The author of the Nature article, Jeff Tollefson, calls this a “grim milestone” (however, no reason for this being either grim or a milestone is given).
Those interested in this trivial issue should read the Nature article. There are some interesting points in it concerning suspected and hypothesized sources of the methane and the reason for the rather odd pattern of rise and fall seen in multi-year data.
However, here is:
The Bottom Line
1. Always look at the units attached to any numerical data.
1900 ppb (parts per billion) is 1.9 ppm (parts per million)
Or, in percentage of the atmosphere:
0.000 19 Percent [%]
2. What that means in the Real World™ is that the amount of methane in the atmosphere is so small — there is more neon and helium in the atmosphere than methane — that if you searched for a molecule of methane, and individually sorted through a BILLION MILLION molecules, you might find one or two. You might find none in your first billion million, but if you sorted enough billions millions, your find would average out at just under 2 per billion million. (Good Luck!) (thanks to many sharp-eyed readers for pointing out my getting the b’s and m’s mixed up — kh)
3. As the Earth continues to warm and green as it comes out of the Little Ice Age, we see more life which means more methane. More life is a Good Thing.
4. Atmospheric Methane has spiked! — to almost zero.
# # # # #h
Author’s Comment:
Almost Zero is an important issue. Many of the most popular dangers and harms touted in the popular press are about the crisis of “things” being discovered at levels which are best described as “Almost Zero”. This is the nutty misapplication of the precautionary principle, where the mere existence — the mere detection — of a thing is automatically equated with harm.
The more advanced technology becomes in detection, the more potentially harmful things are found and the more alarms are raised.
Give examples in the comments if you wish.
# # # # #
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Our bad for allowing the EPA to force landowners to restore the biggest source of methane, wetlands. Perhaps draining wetlands again to make charging stations for EVs will solve the problem.
Recent research agrees with you.
https://research.noaa.gov/article/ArtMID/587/ArticleID/2769/New-analysis-shows-microbial-sources-fueling-rise-of-atmospheric-methane
Just because the political shills at the IPCC want to demonize natural gases to pursue their agenda, it does not mean that nature is bad. Methane production from natural sources has been going on since the beginning of life.
Human methane production is largely from also natural sources, such as rice farming, but that does not make it bad. The short half-life of methane in the atmosphere and the economic fact that natural gas production by humans demands that methane is controlled and not wantonly released.
The goal of this production is to sell the gas and the goal of the purchaser is to use it productively energy-wise. Pretending that there needs to be a second layer of regulation beyond the already existing regulations and precautions, a la Obama, is simply an attempt to make natural gas more expensive, which means this is a political agenda.
Of course the usual suspects will claim that methane has spiked by 15%. Never mind that the total amount of the increase is minuscule. As a commenter has mentioned, Almost zero.
As someone once said: “drain the swamp!”
Paul ==> The problem was that they drained and plowed all the “swamps”. That led to less life. Less Life is Bad.
John the Econ ==> Yes . . . but . . . . restored wetlands also means more wetland birds, more ducks and geese. In other words, more life. More Life is Better.
Like the dude who thrives on posting about “zetajoules” of ocean heat in the UAH reports…
The correct unit for that measurement is atomic bombs per second/hour/day.
No Olympic swimming pools?
Umm, cricket pitches??
Auto
Carlo ==> Better Zeta than META…..
Methane, carbon dioxide etc are just the platform or cover up to the real issue that we are living in misanthropic era. Oops–the misanthropes had some slip when they try to label the current age as the Anthropocene when they real meant misanthropic or misanthropocene age.
eo ==> Come on now, some of us misanthropes are nice guys, deep down.
On point # 2, “…if you sorted enough billions, your find would average out at just under 2 per billion.”
No. The numbers are correct in #1. Therefore, one would find 1900 molecules per billion or about 2 per million.
Sometimes enthusiastic mockery gets away on us
Happens to me too
I represented per unit as percent
Oops
Obviously someone has never been to the Mooserack Sportsman’s Club on “Beans ‘n Cornbread” Friday.
Scissor ==> Always, Scissor beats Paper.
Love good readers!
Unbridled and unfounded fear needs nothing more than a weak heart and weaker bladder to blossom. As reason fails the bed-wetters rise and the future dims. But the truth never fails to correct the idiocy and, in time, we will get back to focusing on what really matters and what brings our bright future closer. Those who worship fear will fail, those with courage will prosper.
I love your term ‘the bed-wetters’ for the alarmists. I will keep using it!
The full and correct term is “bed wetting red diaper doper babies.”
Thanks for the post, Kip. A couple of comments:
First, you say:
You mean million, not billion. The concentration of methane is about 1800 parts per billion, or ~ 2 parts per million.
Second, the “argument from tinyness” doesn’t work in the real world. For example, I weigh about 75 kg. The lethal dose of botulinus toxin for someone of my weight is 1E-7 grams … or 0.0000001 grams.
That’s about 1.3 parts per trillion, far, far smaller than the amount of methane in the atmosphere … and it would kill a person.
Here’s another example. Ozone in the atmosphere is about 600 parts per billion, a third of the concentration of methane … but if it disappeared, the resulting increase in ultraviolet would be hugely damaging to plant and animal life.
As I said … the “argument from tinyness” is not borne out by what happens in reality. Very small amounts of certain things can have a very big effect.
w.
Very unlovely for you and the Botulism but the atmosphere is not a living thing.
Methane is not “Methane Poison”
(Not yet it’s not, I shouldn’t have said that)
What is Ozone?
Where does Ozone come from?
What makes Ozone?
Is it an inheritance from our Grandparents, the Neanderthals, the Big Bang?
How stable is Ozone, does it have a half-life?
What does the half-life depend on?
What does UV do to Ozone and or vice-versa?
What does UV do to methane?
What does Ozone do to methane?
What are the absorption mechanisms?
Is the UV re-radiated after Ozone absorption and if not why not – longer wavelength energy is re-radiated inside the GHGE and goes on to Waste The World.
Why does Ozone eat UV but CO2 not eat IR?
Can the same/one dose of 1E-7 of botulism kill everybody in the same way Up/down/where-ever welling welling Infra-Red wastes the world?
So the great Willis that has always claimed that CO2 is not harmful, now claims that an increase in something is?
You are comparing something toxic to something that is not. I’m sure there is some latin term for that.
Talking about ozone and UV is a little strange. Many plants are grown under Halogen lights and there is no real connection with UV damage to plants, it’s possibly the same for animals. No long term studies but an assumption.
Your argument for ‘tinyness’ is useless and irrelevant.
Read it again, Alexy, Willis never said or suggested that CH4 is harmful. He only said that it is not necessarily inconsequential.
More precisely, he said that the “tinyness” of CH4’s concentration doesn’t make it necessarily inconsequential. Which is right.
I read it several times before commenting. I couldn’t believe that he would use an argument, that the warmists use, to say that small quantities of deadly stuff can k!ll you and relate it to CO2 and CH4. He actually didn’t say anything about CO2 or CH4, but the implication was there nevertheless. Afterall the post is about CH4 and a slight increase thereof.
There was no hint of an implication that CH4 is harmful, in what Willis wrote.
It was perfectly clear: he gave two good examples of things which, in tiny amounts, have great consequences. One of them (botulinum toxin) is very harmful in tiny concentration. The other (ozone) is very beneficial in tiny concentration.
Nothing Willis wrote suggested that CH4 is more like botulinum toxin than like ozone.
Ye-es but someone’s implausible assertion of a large effect for tinyness isn’t persuasive either. Similarly alarmist claims are made for very small differences in ocean pH for instance. Ozone might be the exception, maybe, at least for life not adapted to extra UV. However, for planetary temperature as such, who has ever corroborated large effects from something as slight as the two parts per million of CH4?
I have to say I agree with you, Willis. To Kip, if Willis is the voice of reason, you are doomed.
Well you think we are doomed regardless as you hate humanity for thriving with fossil fuels.
Willis- Thanks for pointing out that claims of insignificance due to small concentration are completely unscientific. Breathing air with 400 ppm CO2 has no effect on humans but try that with HCN or H2S.
Comment about “tinyness” in general. When reporting chemical concentration values at levels of parts per trillion to parts per billion the method of sample collection, storage, preparation, and analysis and the collection site location become very important in the validity of the data. Poor collection sites, contamination of samples during processing, instrument sensitivities, and operator qualifications can easily compromise results. It seems that when these very low concentrations are reported as fact it requires the generator of the data to clearly provide this type of information along with some sort of error analysis. It would be nice to hear from someone with extensive analytical lab experience (mine is limited) to comment on the issue accuracy and precision of very low concentration data.
Often CO2 is argued to be tiny in effect at a mere 400ppm. Yet as the base of all life, it’s the heaviest-lifting molecule of all! It’s just too busy supporting life to help much with warming the planet ; }
Botulinus is a powerful neurotoxin. This toxin is made by the bacteria Clostridium botulinum, which requires trillions of multiplying organisms in an infection to produce it. In fact, at anytime the estimate of the total number of bacteria in a 70 kg “reference man” is 3.8·1013.
Therefore, your analogy about small numbers in weight from bacterial infection as an example is flawed. It takes trillions of bacteria to do that. Size is relative.
w. ==> Yes, millions, billions, zillions. All have too many zeros. (sarc)
Arguing against the argument from tininess (the quality of being tiny) always always depends on the details — because tininess depends on the details. They call these gases Trace Gases because, well, there is just a trace (near zero) amount of them.
For instance, ground level ozone — above certain concentrations — is damaging to lung health. Whereas stratospheric ozone is protective of earth life. Further, no one really cares much about the tiny bit of ozone in the in between areas. Ozone is not well mixed vertically so — as with everything — it depends.
Botulinus toxin has made many of my doctor friends very rich indeed. One in Idaho gets $300 cash money from the patient for every BT injection he gives (BT is not covered by most insurance). Many patients get multiple BT injections to reduce wrinkles every six months. He made so much extra the first year alone, that his wife bought him a fire engine red Corvette, which he named “BT”. Your poison is my friends golden goose. You see, it all depends….
Everyone is entitled to have their own opinions on what to be afraid of and what to worry about — for my money, methane would not be one of them — certainly not in regards to climate change.
The major kicker with methane is that I understand it’s absorption band is overlapped by the water vapor band, so it will have negligible effect.
Silent but deadly ……
…… the deadly, not so much:
https://www.heartland.org/_template-assets/documents/publications/CO2%20coalitino%20Methane%20and%20Climate.pdf
Pay particular attention to Figure 4. The radiative forcing effect of a doubling of CH4 level in the atmosphere is the difference between the black and red traces. (Look closely!)
They’re burning a lot of methane at Prudhoe Bay today. It’s -40 degrees C and F.
Do you feel like you are standing on shifting sand? The government cannot make up their mind. No on methane, but yes on wetlands. Yes on EV, but no on mining. Yes on wind and solar, but no on nuclear. Good point on pointing out the units. The uneducated would be easily deceived. These folks would not know how to dissect and deconstruct these narratives that are false and misleading to arrive at the deception and falsehoods built into these narratives. Hence, dumbing down of our society. The alarmism should be directed at human stupidity and whether or not we will have the ability to survive as a species or as a society. Is this part of the Great Reset? I think so.
What’s the connection? No one in DC would ever consider these two things are inconsistent. They want more stuff they deem good and less stuff they deem bad – get it sorted. It is that simple. EVs come from motor vehicle dealers. Mines are those nasty places that have really bad pollution.
“They want more stuff they deem good and less stuff they deem bad – get it sorted. It is that simple.”
Unfortunately, I think you are correct.
Simpletons are running the show at the present time.
Yes, California just introduced a bill in its legislature to ban offshore mining for rare earth metals. It will pass and is being sold as “pollution prevention” and “protection of the coast”. No one currently mines the deep ocean.
Of course, California also wants to ban all gasoline engines and switch exclusively to EVs to save the world. Apparently, mining the materials necessary to do this will stay with the Chicoms somewhere else in the world, to save the world.
That’s the current thinking of California elected officials, as shown by their actions.
Kip, you said, “that if you searched for a molecule of methane, and individually sorted through a BILLION molecules, you might find one or two.”
Shouldn’t that be “a MILLION” instead of billion?
Clyde ==> Yes, hard day — as I said above “Millions, Billions, Zillions….all have too many zeros!” That might have been Bill Gates about his money though….
Ordinary man can’t catch a break….can’t win…becuz Bad Man keeps producin’ that black evil C stuff into our atmosphere…..it’s even changin’ the smell of our air.
Well, the smell of snow certainly.
The concentration of CO2 in our lungs is 50000ppm, now tell me how we can perceive a change in the atmosphere from 380ppm to 420 ppm
I am still awaiting a response for two years plus now, from two alleged Climate Scientists, to explain why in the past there was over 19 times the amount of CO2 in the atmosphere than today, yet the World was smack bang in the middle of an Ice-Age! I despair of hearing people, usually young & technically & historically ignorant, claiming how there will be massive increases in diseases like Malaria due to Globul Warming. I point out to them that the worst known outbreak occurred in the 1920s at a place called Archangel, deep inside the Arctic Circle, but it simply falls on deaf ears, sadly!!!
Alan ==> Maybe your emails got lost in the ether?
Seriously, I have only about an 80-90% response rate when writing to study authors — very politely and professionally.
None dare say that the rise in CO2 may be the result of global warming. They would be excommunicated for their heresy!
They would be wrong.
Unlike for CH4, we have robust numbers for how much of the precious air fertilizer (CO2) mankind produces, because we have fastidious bean-counters who keep close track of the amounts of fossil fuels and concrete we produce and use, and we know quite precisely how much CO2 results from those processes. That means we know, beyond any doubt, that, every year since precise measurements began (1958), nature has been a net-remover of CO2 from the atmosphere, and mankind has been a net-contributor of CO2 to the atmosphere. The one and only reason for the beneficial rise in atmospheric CO2 concentration is that mankind’s additions of CO2 are larger in magnitude than nature’s removals.
Dave, have an uptick for the phrase ‘precious air fertiliser ‘. That should be used whenever CO2 is mentioned.
JF
Nice link to Scientific American back when it wasn’t propaganda but, CO2 is way more than mere fertilizer, it is a necessary component of photosynthesis. We are a carbon based life form, every carbon atom in your body was once CO2 in the atmosphere.
“The one and only reason for the beneficial rise in atmospheric CO2 concentration is that mankind’s additions of CO2 are larger in magnitude than nature’s [NET] removals.”
Land and ocean CO2 sources and sinks are twenty times greater than fossil fuel emissions. It’s quite possible, if not likely, that the absolute annual growth in “natural” sources of CO2 is greater than that of the bean-counted processes.
Termites emit 10 times the CO2 that humans do. Science 05 Nov 1982: Vol. 218, Issue 4572, pp. 563-565 DOI: 10.1126/science.218.4572.563
Bean counters do not tally the world termite population, however.
The one and only reason for the beneficial rise in atmospheric CO2 concentration is that mankind’s additions of CO2 are larger in magnitude than nature’s removals.
But not by much! And, while we do have a pretty good handle on anthro’ emissions, we don’t know the natural fluxes as well.
Sounds like the spontaneous emergence of global warming from global warming, in an unknowable way. This is exactly the magic of the markets in economics, from von Hayek.
Now look at the economics, energy price inflation, crashes, bail-outs.
We are back to Newton’s Alchemy which Maynard Keynes found to be his main activity!
Clyde ==> Yeah, but what’s with the “itself” in that quote?
I’m not sure what your point is. Humans are making some small, but uncertain contribution to the rising CO2. However, my analyses suggest that it is primarily a response to an Earth that has been warming for about 12,000 years.
Clyde ==> The quote from the Times’ article says “global warming itself is ….”.
That’s just a weird way to say “global warming is….”
What’s with the “itself” bit?
Well we often said that the greenies plans for power generation relied on unicorn farts. What does a unicorn fart consist of? Methane. Unicorns are causing the unprecedented rise.
The good news is that we have the technology to convert methane and unicorn farts into less harmful CO2. A desirable by-product of the conversion is electricity! What could be greener than that?
Yes, and CO2 to trees, and trees to lumber, and lumber to houses, and houses for the homeless.
“According to NOAA, the atmospheric methane concentration has continued to increase since 2011 to an average global concentration of 1892.2 ppb as of December 2020.” (Wikipedia)
That’s 1892.2 parts per billion. Not 1892.1 or 1892.3, Now that’s impressive precision. Wonder what the Measurement Uncertainty is. I’d bet it’s over +/- 200 ppb.
I personally try not to worry about stuff that needs to be measured in ppb.
Rick ==> Adding a decimal fraction to your numbers make them “more true” and “more science(y)”
The bigger the ‘bad’ number, and the more decimals places, the more impressed laymen will be — they hope!
Thus, the Rule of Thumb is to present the public with scary numbers that are as big as possible that still contains one or more significant digits beyond the decimal point.
I will post again for the third time in three days. The methane GHE issue was definitively settled at WUWT on 4/11/2014 by Dr. Tom Sheahan in his guest post ‘Methane: the irrelevant greenhouse gas.’ Just basic physics. Let’s move on.
In the real world, all lab GHE methane absorption bands are completely covered by water vapor, which is millions of times more prevalent. Much ado about nothing, yet again.
or, as the (formerly little) girl says when the Ig Noble prizes are awarded at Harvard but Go acceptance speech overtimes: Please Stop. Stop!
Why is this voted down? Just read Wijngaarden and Happer and know this is spot on.
Even worse, Kip, atmospheric methane has spiked from 1625 ppb in 1983, to 1,900,000 parts per trillion in 2022! One million, 900 thousand parts! It’s a bigger number!
Horrors! Call the fire brigade.
We need to measure this change in concentration using sensible units like number of atomic bombs going off per day.
The units you are referring to are “hiroshimas”
An entire Ice-Age could slip by unnoticed in the round-off error.
Has anyone got the longer term data plotted with a graph that starts at 0 on the Y axis?
‘Cos I think this is like the CO2 version where truncating that axis makes it exaggerated but poltting it properly would shows an almost flat line.
Into ModTran, put US standard atmosphere, fixed relative humidity, and a type of cloud cover that results in about 240 watts…. Save the result as the “background case”.
Double methane in Modtran to 3.8 ppm from 1.9 ppm, which means twice as many rice paddies, termites, cow pastures, leaky pipelines…etc..and you only get 0.17 C increase as the new surface temperature…so no biggie…
Also, regarding the 84 times GWP for CH4….99.9+% of IR photons that hit either a CH4 or CO2 molecule will rattle the molecule a bit harder and warm up the thousands of other air molecules around them. Emitting an IR photon of the same energy is a relatively rare occurence compared to kinetics.
So an IR photon will be absorbed by a CH4, or a CO2, or a H2O, mostly warming a wee bit the surrounding air molecules, or possibly zip through the atmospheric window….but implying CH4 is going to cause 84 times the warming as CO2 has lost sight of how many IR photons are available from the surface to start with.
“Double methane in Modtran to 3.8 ppm from 1.9 ppm, which means twice as many rice paddies, termites, cow pastures, leaky pipelines…etc..and you only get 0.17 C increase as the new surface temperature…so no biggie…”
Yes it needs to be pointed out how little methane’s effect will actually be. It is on track to increase by about 0.5 ppm by 2100, way less than doubling to 1.9 ppm and subsequently way less than a 0.17C in global temperature.
Kip, you asked for examples.
In Ontario, dioxin, which a hex ring featuring chlorine, and a natural consequence of forest fires, is absorbed into the wood of trees used for making paper. The source is the trace amounts of chlorine found in biomass.
Ontario’s milk cartons are made from paper made from pulp made from wood occasionally exposed to forest fire smoke.
Containers of milk are coated with an impermeable membrane and upon chemical inspection were found to contain dioxin at a concentration of 50 parts per trillion. No doubt that was on the limit of detection at the time. In an abundance of caution, all the product was pulled from the shelves and destroyed.
Let us assume a carton weighs 100 g. The dioxin content, if you ate the whole thing, would be 0.0001 micrograms. That is 1/1000th of the mass of hair you could shave off a flea’s balls.
Madness and waste.
Alarmists are innumerate and think one part per billion is a higher concentration than one part per million.
Crispin ==> You tell those Canadian barbers to leave those fleas’ balls alone! (Disgusting practice, if you ask me.)
What bothers me with graphs like the one presented here is the scale. I’m not saying the scale is wrong but the graph makes it look like we have a real problem whether we do or not. When people post a graph like this I would like them to provide a second or third graph for comparison. The scale on this graph went from 1600 ppb to 1950 ppb. A graph should be included that shows a scale from 1000 ppb to 1950 ppb and one with a scale from zero to 1950 ppb. The information wouldn’t change but our perception of what we are looking at would certainly change.
Kip: “that if you searched for a molecule of methane, and individually sorted through a BILLION molecules, you might find one or two”
With 1900 ppb, I think that should read “MILLION”
Hans ==> Thank you kind reader….I love careful readers.
Now my lifetime record of errors has doubled! to two….. (not really, I make a lot of typos….)
To err is to be human. The trick is to just barely be human.
A gas will fill all available space. Lot’s of gasbags out there.
The reason why methane concentration stays very low is that it oxidises rapidly in the atmosphere.
Here are CO2 and CH4 graphed together, for 1800-2021 (the CH4 value for 2021 is an estimate):
Interactive version: https://sealevel.info/co2_and_ch4.html
I chose the relative scaling of the CO2 and CH4 axes so that the relative visual magnitude of changes in the two traces would very roughly approximate the relative warming effect of changes in the levels of the two gases. (However, the absolute height of the CH4 trace in this graph, relative to the bottom of the graph, greatly exaggerates its total warming affect, compared to CO2.)
Additional CH4 is variously estimated to have between 20x and 80x the warming effect of the same amount of additional CO2. I used 25:1 so that the grid lines would line up nicely in the graph (and it is also very close to the 26.5:1 figure from the first two rows of AR6 Table 8.A.1, p.731 [alt]), but 40:1 or 45:1 would have been more accurate: with methane and carbon dioxide at current levels, it is calculated by both MODTRAN Tropical Atmosphere and the NCAR Radiation Code that a 0.1 ppmv increase in atmospheric methane level has about the same warming effect as a 4.5 ppmv increase in CO2 level.
The main methane feedback mechanism is negative (attenuating). It is simply that the atmospheric lifetime of methane is only about a decade, and higher atmospheric methane levels accelerate the rate at which natural oxidative processes which remove it.
CH4 removal processes (mainly oxidation) dwarf the rate of CH4 accumulation in the atmosphere. The rate of increase in CH4 concentration in the atmosphere is only about 0.01 ppmv per year, which is less than 1/30-th of the rate of anthropogenic CH4 emissions. That means atmospheric CH4 level responds very quickly to changes in CH4 emission rate, and if CH4 emission rates cease increasing then the level of CH4 in the atmosphere will rise very little before plateauing.
Atmospheric lifetime
Even if you don’t burn it, methane in the atmosphere oxidizes fairly rapidly, changing ultimately into small amounts of CO2 and water:
CH4 + 2⋅O2 → CO2 + 2⋅H2O (that’s very simplified; see details [html] [2])
Various sources give the half-life of CH4 in the atmosphere as 6 to 8 years, which would make the average lifetime 1.4427 times that (because oxidation is an exponential process, rather than linear), yielding an average lifetime for a molecule of CH4 in the atmosphere of 8.7 to 11.5 years. The AMS gives a figure of 9.1 years (from Pranther et al 2012, which actually reports a figure of 9.1±0.9 years). However, page 11 of this presentation by Prof. Lyatt Jaeglé gives the directly-calculated atmospheric lifetime of CH4 as ≈8 years, but identifies a feedback mechanism which she says effectively increases the atmospheric lifetime of additional CH4 to ≈12 years.
Call it 8-12 years. That’s pretty short. It means the only reason CH4 levels are as high as they are (about 1.9 ppmv† = 5.58 Gt) is that total CH4 emissions (natural + anthropogenic) are already high (between 580 and 710 Mt/yr). There would have to be a very large,‡ sustained increase in CH4 emissions to cause much increase in long-term average atmospheric CH4 levels.
Note that CH4 removal processes (mainly oxidation) dwarf the rate of CH4 accumulation in the atmosphere, and they accelerate with increasing atmospheric methane concentration, making them negative feedbacks. Assuming the Pranther atmospheric lifetime estimate (9.1±0.9 years), we can calculate that the rate of increase in CH4 level (which averages about 0.01 ppmv/year) is only about 1/60-th of the rate of the CH4 removal processes, and only about 1/35-th the rate of anthropogenic emissions. That means the CH4 level responds very quickly to changes in CH4 emission rate, and if the CH4 emission rate were to cease increasing then the level of CH4 in the atmosphere would rise at most only a few percent before plateauing.
†Methane levels vary slightly with measurement location; this site has some maps.
‡How large is “very large?” Well, for comparison, it would take about 3 Gt of CH4 to increase the atmospheric methane level by 1 ppmv.
Radiative forcing, and warming effect
(Note: for a similar discussion w/r/t CO2 see: https://sealevel.info/Radiative_Forcing.html [or synopsis])
The radiative forcing from additional CH4 in the atmosphere can be determined though line-by-line spectral calculations, which, though daunting in their complexity, have been done most comprehensively by van Wijingaarden and Happer:
● van Wijingaarden & Happer (2020), Dependence of Earth’s Thermal Radiation on Five Most Abundant Greenhouse Gases
● van Wijingaarden & Happer (2021), Relative Potency of Greenhouse Molecules
This is Figure 5 from van Wijingaarden & Happer (2020); click here to enlarge it:
Do you see the difference between the red trace and the black trace? (Look closely!) That’s the calculated effect on Earth’s radiative emissions from a hypothetical doubling of CH4 level.
A doubling of CH4 concentration (from the current 1.9 ppmv to 3.8 ppmv) would cause a TOA radiative forcing of +0.7 W/m². Very roughly ⅓ °C of eventual warming can be expected for each 1 W/m² of radiative forcing, so doubling CH4 concentration would cause eventual (equilibrium) warming of about 0.2 °C.
Positive water vapor feedback might increase that slightly, but the overlap between the LW IR absorption spectrums of CH4 and H2O vapor reduces that amplification, so the possible net warming effect of a doubling of atmospheric CH4 concentration is certainly less than 0.3 °C.(Ho, hum.)
Great post. You and DMackenzie above have nailed the how much warming will CH4 actually cause question. The answer is, “Essentially nothing!”
Any winning essay here at “Watts Up With That” should contain a section on methane pointing out how little it’s effect on global temperature actually is.
Steve ==> Is “Essentially nothing!” more than or less than “Almost Zero!” ??
Dave B ==> Now that’s something — a 900 word comment to a 500 word essay. that’s accelerating word level.
(Good comment, though far too serious for a tongue-in-cheek piece. 🙂
A really skilled writer could condense that to 25 words or less. 🙂
No worries. It is not gh gas warming the atmosphere.
https://breadonthewater.co.za/2021/11/25/an-inconvenient-truth/
@ur momisugly Kip
I would be interested to hear your say about my opinion on what does make it warmer here. Click on my name.
Henry ==> Give me a day — I’ve opened your page in my To_do window 🙂
Thx.