Methane is like the radical wing of the carbon cycle, in today’s atmosphere a stronger greenhouse gas per molecule than CO2, and an atmospheric concentration that can change more quickly than CO2 can. There has been a lot of press coverage of a new paper in Science this week called “Extensive methane venting to the atmosphere from sediments of the East Siberian Arctic Shelf”, which comes on the heels of a handful of interrelated methane papers in the last year or so. Is now the time to get frightened?
No. CO2 is plenty to be frightened of, while methane is frosting on the cake. Imagine you are in a Toyota on the highway at 60 miles per hour approaching stopped traffic, and you find that the brake pedal is broken. This is CO2. Then you figure out that the accelerator has also jammed, so that by the time you hit the truck in front of you, you will be going 90 miles per hour instead of 60. This is methane. Is now the time to get worried? No, you should already have been worried by the broken brake pedal. Methane sells newspapers, but it’s not the big story, nor does it look to be a game changer to the big story, which is CO2.
[Note: Edited Toyota velocities to reflect relative radiative forcings of anthropogenic CO2 and methane. David]
For some background on methane hydrates we can refer you here. This weeks’ Science paper is by Shakhova et al, a follow on to a 2005 GRL paper. The observation in 2005 was elevated concentrations of methane in ocean waters on the Siberian shelf, presumably driven by outgassing from the sediments and driving excess methane to the atmosphere. The new paper adds observations of methane spikes in the air over the water, confirming the methane’s escape from the water column, instead of it being oxidized to CO2 in the water, for example. The new data enable the methane flux from this region to the atmosphere to be quantified, and they find that this region rivals the methane flux from the whole rest of the ocean.
What’s missing from these studies themselves is evidence that the Siberian shelf degassing is new, a climate feedback, rather than simply nature-as-usual, driven by the retreat of submerged permafrost left over from the last ice age. However, other recent papers speak to this question.
Westbrook et al 2009, published stunning sonar images of bubble plumes rising from sediments off Spitzbergen, Norway. The bubbles are rising from a line on the sea floor that corresponds to the boundary of methane hydrate stability, a boundary that would retreat in a warming water column. A modeling study by Reagan and Moridis 2009 supports the idea that the observed bubbles could be in response to observed warming of the water column driven by anthropogenic warming.
Another recent paper, from Dlugokencky et al. 2009, describes an uptick in the methane concentration in the air in 2007, and tries to figure out where it’s coming from. The atmospheric methane concentration rose from the preanthropogenic until about the year 1993, at which point it rather abruptly plateaued. Methane is a transient gas in the atmosphere, so it ought to plateau if the emission flux is steady, but the shape of the concentration curve suggested some sudden decrease in the emission rate, stemming from the collapse of economic activity in the former Soviet bloc, or by drying of wetlands, or any of several other proposed and unresolved explanations. (Maybe the legislature in South Dakota should pass a law that methane is driven by astrology!) A previous uptick in the methane concentration in 1998 could be explained in terms of the effect of El Niño on wetlands, but the uptick in 2007 is not so simple to explain. The concentration held steady in 2008, meaning at least that interannual variability is important in the methane cycle, and making it hard to say if the long-term average emission rate is rising in a way that would be consistent with a new carbon feedback.
Anyway, so far it is at most a very small feedback. The Siberian Margin might rival the whole rest of the world ocean as a methane source, but the ocean source overall is much smaller than the land source. Most of the methane in the atmosphere comes from wetlands, natural and artificial associated with rice agriculture. The ocean is small potatoes, and there is enough uncertainty in the methane budget to accommodate adjustments in the sources without too much overturning of apple carts.
Could this be the first modest sprout of what will grow into a huge carbon feedback in the future? It is possible, but two things should be kept in mind. One is that there’s no reason to fixate on methane in particular. Methane is a transient gas in the atmosphere, while CO2 essentially accumulates in the atmosphere / ocean carbon cycle, so in the end the climate forcing from the accumulating CO2 that methane oxidizes into may be as important as the transient concentration of methane itself. The other thing to remember is that there’s no reason to fixate on methane hydrates in particular, as opposed to the carbon stored in peats in Arctic permafrosts for example. Peats take time to degrade but hydrate also takes time to melt, limited by heat transport. They don’t generally explode instantaneously.
For methane to be a game-changer in the future of Earth’s climate, it would have to degas to the atmosphere catastrophically, on a time scale that is faster than the decadal lifetime of methane in the air. So far no one has seen or proposed a mechanism to make that happen.
References
Dlugokencky et al., Observational constraints on recent increases in the atmospheric CH4 burden. GEOPHYSICAL RESEARCH LETTERS, VOL. 36, L18803, doi:10.1029/2009GL039780, 2009
Reagan, M. and G. Moridis, Large-scale simulation of methane hydrate dissociation along the West Spitsbergen Margin, GEOPHYSICAL RESEARCH LETTERS, VOL. 36, L23612, doi:10.1029/2009GL041332, 2009
Shakhova et al., Extensive Methane Venting to the Atmosphere from Sediments of the East Siberian Arctic Shelf, Science 237: 1246-1250, 2010
Shakhova et al., The distribution of methane on the Siberian Arctic shelves: Implications for the marine methane cycle, GEOPHYSICAL RESEARCH LETTERS, VOL. 32, L09601, doi:10.1029/2005GL022751, 2005
Westbrook, G., et al, Escape of methane gas from the seabed along the West Spitsbergen continental margin, GEOPHYSICAL RESEARCH LETTERS, VOL. 36, L15608, doi:10.1029/2009GL039191, 2009
“instead of it being trapped by fresh water and oxidized to CO2 in the water”
I’m guessing the use of the word fresh was a typo, as this is seawater here.
[Response: It’s amazing how incompetent I am at proof-reading! David]
Glad to read the sober and conservative tone of this post!
On the other hand, would it be true to say that a prediction of AGW has come to pass? Increased venting of methane from Arctic resevoirs has often been mentioned .. methane concentrations have been increasing in the atmosphere … but NASA do not include it among their 5 indicators of Global Warming (Sea Level, Arctic Sea Ice, Atmospheric CO2 Concentration, Global Surface Temperature, Ozone Hole).
How good or bad is this news? Does it push the indicators more into the red? Or are they “as you were”? Assume these results will be confirmed.
https://www.realclimate.org/index.php/archives/2010/03/arctic-methane-on-the-move/
First off, David, thanks for a very nice summary. I think this information will be accessible to all.
More importantly, this piece shows how scientists are not “alarmists” despite the constant claim that they are.
Thank you.
Thank you for this (and real climate generally!). I’ve been worried about the impications of this paper since I read a reference to it in a blog suggesting that this was really bad news. Thankyou for putting it in context.
Subscription required for the Science article.
Thank you for the great article. I’m less worried about methane now.
Here’s a graph from the Shakhova paper: Methane Fluxes Venting to the Atmosphere from the East Siberian Arctic Shelf
Thanks for the review, David.
I would guess that hydrates are not involved in this case as the sea in this area is so shallow, and it’s entirely outgassing from organic-rich sediments beneath the permafrost?
Cheers – John
[Response: I think that’s a possibility for the Siberian margin data, still an open question. David]
Thanks David, this is very helpful. And I think Scott is right; this can be cited as an example of how Real Climate brings reality to the table, correcting misunderstandings in either direction.
By the way, I just finished “The Climate Crisis.” Thank you for this good summary and commentary on the IPCC 2007 report. I did note a couple of minor things that I think got past the editors and will give them here in case others have the book.
p. 14, “Figure 6.14 in Chapter 6” should be “Figure 3.18 in Chapter 3”
p. 51, Figure 3.7, I believe the sign is reversed on the PDSI 1 axis
It’s nice to see this news put into context. I wonder – will atmospheric methane will become more significant in the future? We could have a big impact on atmospheric CO2 by reducing emissions from fossil fuel burning, but it might be more difficult to reduce the emissions of methane from wetlands and oceans, and the CO2 resulting from it. Is that the case?
More metaphors please.
I really like the metaphor of being in a broken car about to crash at 80mph. A few people saw the crash coming, some now see it unfolding. Too many have not seen it yet, some will never see it. Some completely deny the possibility of a crash.
Thanks for explaining it all.
I get reamed sometimes for making points like those in this important methane update (pushing back against some of the overheated coverage elsewhere), so this is very welcome. Great driving analogy, proving that scientists can do some of their own communicating (in a world of shrinking conventional media). More background from Dlugokencky, Martin Heimann, Euan Nisbet and others on Dot Earth: http://j.mp/ch4heat
David wrote: “What’s missing from these studies themselves is evidence that the Siberian shelf degassing is new, a climate feedback, rather than simply nature-as-usual, driven by the retreat of submerged permafrost left over from the last ice age. However, other recent papers speak to this question.”
The other recent papers you discuss still seem to be ambiguous on that point.
[Response: very]
What additional science is needed in order to definitively determine whether this — and other such methane emissions that are being observed — are, in fact, new and caused by AGW, and are therefore actual AGW feedbacks; and if so, whether and how rapidly they are increasing?
[Response: They need to figure out where the methane is coming from and why. Then wait and see how it changes with time. David]
RE: “CO2 is plenty to be frightened of…”
Yep, and it keeps contributing to the three years of steady Artic ice growth since the low in 2007! We are shivering all this winter, all over the northern hemisphere with the blizzards, the record snow, record cold, snow in ALL fifty states for the first time that we know of…oh geez! This CO2 issue has the entire population of Earth worried that if levels keep rising, it is gonna continue to get colder and colder each winter. Check out the latest sea ice extent: http://nsidc.org/data/seaice_index/daily.html
[Response: You win the distorted cherry pick of the day award–so far.–Jim]
So, how do we capture and burn it and turn it into energy that can be used to displace fossil fuels?
If it’s going to leak into the atmosphere, let’s figure out how to make it do something useful in the process.
[Response: It is a fossil fuel. David]
Tamino, last August, posted graphs (here) which suggest that a spike in both Arctic and Antarctic methane started in the last couple of years. Have those spikes turned down or is his data simply too speculative?
Hi David,
Thanks for the calm, thoughtful, and well-written article. I think you missed part of the reason methane releases capture people’s imaginations: it’s exactly their shorter-term nature. The slow, steady creep upwards of CO2 is, sadly, just too gradual to get people’s attention. Even the names play a part; CO2 sounds innocuous. Methane sounds dangerous. It catches on fire if you hold a match to it!
It’s like a canary in a coal mine. The rational approach for most of us is, don’t go into poorly ventilated and supported holes in the ground. But given that you know you’re in dangerous territory, and have decided to put up with that, the canary tells you when you’re in more urgent trouble.
SecularAnimist, if you’re truly secular, you’ll stop putting “definitively” in italics. Science, sadly, doesn’t work that way; it’s like civil court, where you make big decisions on a preponderance of evidence, not criminal court, where you only act if you’re beyond a reasonable doubt. The deniers go even further, saying they want proof, in all caps. Unfortunately, the climate doesn’t work that way. For true absolutes, you have to go to religion.
Andy, IMHO, half the reason you get reamed is not your factual stance, but the way you give the impression that you’re trying to put people to sleep on these important issues. Somehow your writing implies that, if this methane release were worse, you’d still be looking for some little ironic twist to your writing, and scratching around for someone to give the other side of the story, whether there really was one or not. I don’t know how you do this, or the reasons, but that’s the impression that comes across.
Whereas with David’s writing, I get the impression that if it were worse, he’d do everything in his power to clearly and forcefully communicate that to people. (Though, at the margin, I doubt David could bring himself to type in ALL CAPS if his chair had caught on fire.)
Cheers,
Bud
[Response: At the moment I’m in greater danger of my laptop catching fire, but I probably wouldn’t type in all caps in that case either. David]
Re: 13
So I guess that humans are getting slower in the last months, because noone has beaten Usain Bolt’s 100 m since last August…
Nice to see a little bit of restraint. In the usual ‘Oh My God’ world of panic stricken chickens they would all be screaming for a solution right about now.
However I am about to ask something that has occurred to me whilst reading the post and all the comments that may throw a spanner into the works.
You say that the methane is out-gassing at a lower rate than CO2 is being released from other sources (peat bogs and wetlands etc) however the rate is constantly fluctuating so in my view (all be it a narrow one) I suspect that its part of a process that’s like climbing a set of stairs. There is no doubt that carbon emissions are still rising and to add a gas that is 20 times more powerful as a global warming gas into the air in sudden out-gassing events, even if these are only a few years apart, builds a step rise in Carbon content in the atmosphere that will subsequently become the plateau before the next big methane out-gassing event, regardless as to where it comes from. I hope that makes sense?
I suspect that the methane that has out-gassed from the hydrates changes to CO2 in the atmosphere before it returns to the Earth as stored carbon. This is what I would hazard a guess at happens in clouds which are just vapour equivalents of water bodies. How does this affect the whole issue? Surely with CO2 being a longer lived global warming/climate changing gas this also exacerbates the problems?
Oh and I had another look at the Horizon ‘Global Dimming’ episode the other night. Still all a bit spooky to think it could all go either way.
Response by David @ 14:
Only for extremely loose definitions of the term “fossil fuel”. But that’s also besides the point — coal isn’t “leaking” into the atmosphere, it has to be dug out of the ground with considerable effort, and oil doesn’t just jump into our gasoline tanks. Even if methane hydrates are a “fossil fuel”, it would appear that it is venting to the atmosphere for free, and whether we like it or not.
Ice and clathrates have sharp melting points. Conventionally, we assumed that there would be a gradual melting of these compounds from south to north, and that somewhere in the “north” it was always colder than 0C. (Even guys that would not write it in formal context, used the concept in casual contexts.) This notion gave us the idea of gradual over all melt for next few years. Now, we have to admit that these compounds are also melting from the Arctic Ocean south.
We can no longer trust the Arctic sea ice to be a reliable “icebox” keeping the “north” cold. We have to see the reported CH4 releases as part of the reports of declining and “rotting” sea ice. Now, we also have to assume that carbon will be released as tundra melts from south to north AND as it melts from north to south as a result of warming Arctic waters and declining sea ice.
Whether this is “catastrophic” or not depends our economic, engineering, and planning horizon. In the view of a corporate executive, looking at next quarter’s profits – not at all “catastrophic”. In the view of a congressman looking toward his next election, maybe. In the view of a parent looking at his children’s and grandchildren’s future, I think “catastrophic” is exactly the right word.
We need to get all the corporate executives and all the congressmen thinking about our children.
The main post is missing a stop-the-italic tag (or has an excess start-italic tag) in this paragraph, or maybe it’s having the wrong kind of bracket?
{Note: Edited Toyota velocities to reflect relative radiative forcings of anthropogenic CO2 and methane. David]
[Response: Thanks–fixed.]
—–
On the seabed methane — we can hope there are good maps of the seabed there (perhaps the Navy would have them, albeit likely classified). If so they can look for changes in the size and distribution of pingos.
Interestingly, pingos used to be considered the result of freezing ice, but
http://www.google.com/search?q=methane+seabed+pingo
The Toyota example is taking some cheap points. I get the math, but the reality is an accident at 60 MPH in a modern car is survivable. At 90 MPH you are dead. So there is a huge difference.
[Response: OK, so damage probably doesn’t scale linearly with velocity. Maybe you liked it better 70 / 90 mph. David]
The rest of the tone is quite good and helpful. The point about ocean methane being much lower than the land methane emissions is very helpful. My reading of the Arctic sea shelf is that it shallow and therefore there is more methane buried underneath?
I had two followup questions:
1) If there is more methane around than previously accounted for, does that mean historical models that didn’t account for that extra methane are not working correctly?
2) Would extra methane near the Artic circle account for more warming there locally?
[Response: 1. It means the budgets have uncertainties that can accommodate this. 2. Methane is mostly well-mixed in the air, except when they catch a plume like they did, so the warming from it is mostly global. David]
Unclosed italic tag right betwee ‘{‘ and ‘Note’. I wonder what happens if i close it here
I posted a comment on the previous thread, and with the permission of the moderators, I will repeat it here:
Re:Shakhova methane article:
I was directed to
http://www.global-chance.org/IMG/pdf/CH4march2008.pdf
by Mr. Lou Grinzo at climateprogress. In Figure 4 and table 2, a comparison is made between relative global warming potential of sustained releases of CH4 as compared to CO2 at different time horizons. The effect of a sustained release of CH4 has the same GWP as that of a sustained release of 81 times the amount of CO2 over a time of 20 years.The factors for 50,100,250 and 500 years are 57,39,21,and 13.
The authors make the case that using the 21 multiplier appropriate for century timescales is not appropriate, especially in the early decades where GWP would be underestimated by a factor of 80.
I see an estimate of 3.8 teragram/yr CH4 release from North Siberian Lakes in Zimov, Nature, v443, pp71-75, 2006. This has increased by 58% since 1974. Shakhova has 8 Tg/yr from the seabed.
Only including these we have 8 Tg from the seabed, 4 from the lakes, for 12 Tg annual CH4 out. 12Tg of CH4 for twenty years has a GWP over that period of 0.72 Pg sustained CO2 release. I believe that by comparison, annual human fossil and land use CO2 emission is around 30 petagram, so thats round 2% extra in terms of GWP over 20 years.
Not huge, but definitely significant.
If these CH4 releases rise quickly, say by a factor of 10, we cook much quicker. Of course I might have done the math wrong.
sidd
[Response: I’m sure you’re right, a factor of 10 increase in CH4 emission from the Arctic would be serious and bad. David]
Metacomment — Suddenly everything is all in italics. Disconcerting.
[Response: Fixed, thanks.–Jim]
You seem to be missing a [/i] from the EDIT there, David. We’re all emphasized down here! }|:op
Anyway, thanks for this discussion, interesting stuff, if somewhat disconcerting (I don’t dispute that CO2 is enough to be worried about, but observing feedbacks kicking in isn’t exactly adding any feeling of comfort).
A small correction to the reference list: “Shakhova” is twice misspelt “Shakova”, as I discovered when accessing the GRL 2005 article.
Thank you for an excellent post.
[Response: Fixed now, thanks. David]
Hi to all.I’m an amateur climate guy who reads a lot about global warming.I’ve followed all the press releases and most of the science since 1987.RealClimate is wonderful, and an excellent source of reliable information.As I’ve said before, methane is an extremely dangerous component to global warming.Comment # 20 is correct.There is a sharp melting point to frozen methane.A huge increase in the release of methane could happen within the next 50 years.At what point in the Earth’s temperature rise and the rise of co2 would a huge methane melt occur?No one has answered that definitive issue.If I ask you all at what point would huge amounts of extra methane start melting, i.e at what temperature rise of the ocean near the Artic methane ice deposits would the methane melt, or at what point in the rise of co2 concentrations in the atmosphere would the methane melt, I believe that no one could currently tell me the actual answer as to where the sharp melting point exists.Of course, once that tipping point has been reached, and billions of tons of methane outgass from what had been locked stores of methane, locked away for an eternity, it is exactly the same as the burning of stored fossil fuels which have been stored for an eternity as well.And even though methane does not have as long a life as co2, while it is around in the air it can cause other tipping points, i.e. permafrost melting, to arrive much sooner.I will reiterate what I’ve said before on this and other sites.Methane is a hugely underreported, underestimated risk.How about RealClimate attempts to model exactly what would happen to other tipping points, such as the melting permafrost, if indeed a huge increase in the melting of the methal hydrate ice WERE to occur within the next 50 years.My amateur guess is that the huge, albeit temporary, increase in methane over even three or four decades might push other relevent tipping points to arrive much, much, sooner than they normally would, thereby vastly incresing negative feedback mechanisms.We KNOW that quick, huge, changes occured in the Earth’s climate in the past.See other relevent posts in the past from Realclimate.Climate often does not change slowly, but undergoes huge, quick ,changes periodically, due to negative feedbacks accumulating ,and tipping the climate to a quick change.Why should the danger from huge potential methane releases be vievwed with any less trepidation?
Mark J.Fiore
When I linked your post to a forum for general (not AGW) skeptics, one of the resident deniers there called it “typical warmist hysteria.”
They never read anything past the byline, it seems.
Thanks for the excellent summary of the recent methane news, David.
David,
In your(?) book, The Long Thaw, you explained methane hydrates very well, but pictured an alarming scenario, comparable to nuclear winter or an asteroid impact, if as low as 10% of the methane hydrate were to reach the atmosphere (pages 133-136). do you still stand over that? Or are you saying that is a remote possibility only?
[Response: Yeah, that was me. If that much methane did get out, it would be CATASTROPHIC (trying to stretch my literary range here). But it has to come out quickly, and no one has figured out how that could happen. David]
In an earlier post (#2), I put in a wrong like .. I meant this one:
http://climate.nasa.gov/keyIndicators/
Would you say this has pushed the indicators for global warming deeper into the red zone. Same question I asked in #2?
[Response: I think carbon cycle feedbacks in general kind of ratchet up the scariness of the future, yes. David]
Great post, great site… enjoyed the book, also. Not a “rattling good read”, but concise and understandable.
On catastrophic methane degassing: Shakova and Semiletov have proposed a mechanism – the destabilisation of the permafrost cap overlying large methane hydrate deposits that contain a high proportion of free gas. The temperature regime is very different to onshore permafrost and deeper oceanic hydrates, and sensitive to warming of the shallow coastal waters over the ESAS. The new paper establishes a baseline for future measurement – but shows that their hypothesised mechanism is active (though it can’t, obviously, support a claim that it’s necessarily new). S & S have considered the potential for catastrophic release: at the very least their calls for further study need to be taken very seriously. [S&S have a chapter in last year’s WWF Arctic overview , Arctic Climate Feedbacks: Global Implications (available here (pdf), which provides a very good overview of the issue].
[Response: Not to belittle the concern, but this methane degassing would probably take place on a time scale which is longer than the methane lifetime. So it wouldn’t be what I mean when I write catastrophic. It would be bad to have an increased ongoing, chronic release of methane also, and I definitely agree the region should be watched very carefully. ]
[Side issue: David, are there any satellite products that could shed light on atmospheric methane in the area?]
[Response: A satellite called SCIAMACHY is able to detect gas concentration plumes in the air, but I don’t know whether these sorts of plumes could be seen in their data. David]
On methane’s role in the bigger picture: Your analogy explains the primacy of CO2’s role very well, but misses what I consider to be the real danger from an active methane feedback. Release from the ESAS alone has the potential to make any CO2 mitigation efforts futile — ripping the reins from our hands, as it were. We have no sense of the size of that risk at the moment, beyond the data in the S&S paper, but we do have a rapidly warming Arctic to provide a troubling context. One to watch…
It would be more useful to get some estimates of what the scientists involved think that the effect will be over the next 50-100 years, as was done with sea level rise.
To get such estimates, you have to make a lot of predictions about how the biological system is going to react. For the permafrost issue, there is already retreat in the Hudson Bay area:
The permanently frozen ground known as permafrost is retreating northward in the area around Canada’s James Bay, Reuters Feb 2010
What happens to permafrost as it melts? Do shrubs move in? Or do you get bogs, wet and full of methane-generating bacteria?
It is true enough that the methane emitted would be converted to CO2 over time – but a more practical question is how these methane emissions will compare to human efforts to reduce fossil fuel emissions.
Consider a scenario in which we work overtime to build renewable energy infrastructure, while reducing fossil fuel emissions by 50% in 2050 from 2000 levels. Now, is it possible that the natural feedback will overcome that – the methane flux, perhaps similar to the Younger Dryas methane excursion? Or is that not something to worry about?
To answer that, we need to know what kind of rates of permafrost / shallow seabed outgassing should we expect by 2050 – and could it result in an amplification of polar amplification? What does that do to sea level rises?
and why is the ch4 conzentration in the atmosphere stable over the last 10 yaers?
I have read the sidd link in 23. It would seem that use of the 100 year factor linearizes a highly nonlinear process in a way that significantly underestimates the impact of a CH4 release on decadal time scales. Isn’t that a bit dangerous if the climate may be approaching critical tipping points? As David said, “a factor of ten increase in CH4 emission from the Arctic would be serious…” Is that an unreasonable possibility? No one really knows, I suppose, for lack of adequate information at this point. And I am sure there is considerable effort underway to try and find out.
In the meanwhile, would it be possible to run model studies to assess a range of plausible scenarios of CH4 release, using the actual decay function for CH4, rather than a linear CO2 equivalency?
Thanks David.
Large scale methane release, whether chronic or acute, also has implications for the OH oxidation pathway — which could mean that the atmospheric lifetime becomes extended as the OH supply is “used up”.
The SCIAMACHY stuff is interesting, but the last visualisations I can find are from a few years ago. It would be very cool to have near real-time stuff for the ESAS (and elsewhere).
“Most of the methane in the atmosphere comes from wetlands, natural and artificial associated with rice agriculture.” How so? The Edgar 4.0 inventory has rice
at 33 mega tonnes and enteric fermentation at 96 mega tonnes and fugitive
emissions from oil and gas at 72 mega tonnes. Those rice emissions have
a side benefit … 19% of global calories … the 96 mega tonnes
have a side benefit, about 6% of calories with most of that being milk. But
the 96 megatonnes have plenty of extra downstream costs. Huge areas that
could be reforested to draw down carbon are burned each year to prevent that
happening.
The people advocating strong methane reductions (e.g. Hansen) aren’t advocating
switching attention away from CO2, but merely noting that our current methane forcing increments are on a par with out current CO2 forcing increments, and that we can
reduce CH4 without diverting any resources away from the big battle … which
is of course to leave coal in the ground. People who belittle methane
reductions tend to think that while the planet is important, giving up
hamburgers is too dear a price. But such people always mention the HUGE impact
of rice.
http://bravenewclimate.com/2010/02/04/boverty-blues-p2/
[Response: OK, poorly worded, you’re right. Livestock are a bigger source than rice farming, and the fossil fuel industry is big too. I’ll defend myself by saying if you add together both types of wetlands they are the largest source, as I wrote, and I never wrote HUGE. I don’t do caps. David]
Herbert, there seems to be some natural variability in addition to the direct human perturbation. As I understand it, though, there has been an uptick in recent years, and before that stabilization may have been partly due to reduced emissions of methane (including natural gas leakage) from human activity.
“So far no one has seen or proposed a mechanism to make that happen.”
Here’s a patent for one: http://www.freepatentsonline.com/6209965.html. The Japanese are very interesting in hoovering up methane from the sea floor. As oil gets harder to find, coal quality continues to decline, and terrestrial natural gas sources play out, there will be a lot of people interested in hoovering up methane from the ocean.
22. charlie says:
David commented:
Last year I posted
David is probably right. But it doesn’t sound as though he has done the work to “done the work to dismiss it definitively”. Has anyone?
[Response: I don’t think a plume of methane here or there would noticably affect the local climate any more than a cloud here or there would. Heat flows around a lot on Earth. But you’re right, I haven’t thought about it quantitatively. David]
“One is that there’s no reason to fixate on methane in particular.”
“The other thing to remember is that there’s no reason to fixate on methane hydrates in particular, as opposed to the carbon stored in peats in Arctic permafrosts for example. Peats take time to degrade but hydrate also takes time to melt, limited by heat transport. They don’t generally explode instantaneously.”
_____
The permafrost is likely to take many decades at least to thaw, so the methane locked within it will not be released into the atmosphere in one burst, said Stephen Sitch, a climate scientist at the Met Office’s Hadley Centre in Exeter.
But calculations by Dr Sitch and his colleagues show that even if methane seeped from the permafrost over the next 100 years, it would add around 700m tonnes of carbon into the atmosphere each year, roughly the same amount that is released annually from the world’s wetlands and agriculture.
http://www.guardian.co.uk/environment/2005/aug/11/science.climatechange1
“Shakhova notes that the Earth’s geological record indicates that atmospheric methane concentrations have varied between about .3 to .4 parts per million during cold periods to .6 to .7 parts per million during warm periods. Current average methane concentrations in the Arctic average about 1.85 parts per million, the highest in 400,000 years, she said. Concentrations above the East Siberian Arctic Shelf are even higher.”
http://climateprogress.org/2010/03/04/science-nsf-tundra-permafrost-methane-east-siberian-arctic-shelf-venting/#comments
Why do you not mention methane highest in 400,000 years?
Why not mention that the IPCC models not incorporate methane?
There is a diffrence of permafrost and sea sediment methane – why not make the diffrence? Abrupt change comes – “if”, from sea sediments, irreversible thaw from the peat bog.
Methane is the silver bullet in communicating the threat of climate change!
Herbert (32) — Check the Un’s FAO for statistics for estimates on area in rice production and also estimates of the number of cattle. Find someplace which estimates hectares of wetlands otherwise lost to parking lots or whatever.
Just suggestions.
Herbert, your name links to “Zentralanstalt für Meteorologie und Geodynamik.”
What kind of organization is that? Are you a weatherman? Do you have access to current journal articles, or are you only reading old past issues?
The information “stable over the last 10 yaers” was correct — in 2007.
I worry about people who don’t check their facts before posting them.
Was there some problem looking this up?
I’m just an amateur reader, not a weather professional, and this was easy to find.
http://www.nasa.gov/home/hqnews/2008/oct/HQ_08-276_Methane_levels.html
— excerpt from the press release follows —-
The amount of methane in Earth’s atmosphere shot up in 2007, bringing to an end approximately a decade in which atmospheric levels of the potent greenhouse gas were essentially stable. The new study is based on data from a worldwide NASA-funded measurement network.
… Until recently, the leveling off of methane levels had suggested that the rate of its emission from Earth’s surface was being approximately balanced by the rate of its destruction in the atmosphere.
However, the balance has been upset since early 2007, according to research published this week in the American Geophysical Union’s “Geophysical Research Letters.” The paper’s lead authors, Matthew Rigby and Ronald Prinn of the Massachusetts Institute of Technology, say this imbalance has resulted in several million metric tons of additional methane in the atmosphere.
—- end excerpt—
You can find the paper and check for subsequent cites, updates, etc. easily.
Have a look — tell us what you think.
For Herbert, here are recent papers citing Rigby and Prinn:
http://scholar.google.com/scholar?cites=9694380594515227158&hl=en&as_sdt=2000
Thank you for this article, I was hoping that RC would post on the topic to give context to other recent reactions.
Revkin complains above that he is getting “reamed” when “making points like those.” His problem is that while you are putting issues into context, he is doing the opposite, and his post on the topic is a case in point. Nowhere in his article does he take on the issue that the car is travelling 70 MPH and potentially about to accelerate, instead to him it’s all about some scientists’ overreaction to a narrow slice of the whole picture. Just like his recent quibble that an IPCC summary paragraph didn’t have enough caveats to the near certainty of AGW. Blah, blah, blah, confusion and no context, a real disservice.
Hi David, and thanks.
I realise that you wrote “CO2 is plenty to be frightened of, while methane is frosting on the cake” in the context of arctic methane, but I wonder if you wouldn’t mind clarifying anthropogenic methane’s likely role in the warming thus far and into the future?
There is a claim, promoted especially by some in the farm sector, that because methane is short-lived, and because methane levels plateaued for a short time while ruminant numbers continued to increase, efforts to reduce emissions from enteric fermentation are therefore worthless or near worthless.
Thanks again.
[Response: The future of methane is anybody’s guess, given that the present isn’t even all that easy to understand. IPCC Working Group III found lots of ways to mitigate climate change by reducing methane emissions. David]
Kev #18, yes CH4 converts into C02 in the atmosphere.
The following passage is from Weart’s chapter on Rapid Climate Change.
http://www.aip.org/history/climate/rapid.htm
For one group of American scientists on the ice in Greenland, the “moment of truth” struck on a single day in midsummer 1992 as they analyzed a cylinder of ice, recently emerged from the drill hole, that came from the last years of the Younger Dryas. They saw an obvious change in the ice, visible within three snow layers, that is, scarcely three years! The team analyzing the ice was first excited, then sobered — their view of how climate could change had shifted irrevocably.
This passage, more than anything else I’ve read, is what worries me about methane. We may not have yet figured out how such a rapid change was possible, but methane would seem to be the prime suspect.
[Response: No, I don’t think so. Methane does go down when the Earth cools in these so-called “abrupt climate changes”, but it’s not enough radiative forcing to be the fundamental driver, but rather a feedback due to drying wetlands. The abrupt climate changes were physical in origin, to do with ocean circulation and sea ice probably. David]
“CH4 + 2O2 = CO2 + 2H2O
Direct quote:
“So, combustion of 16 mass units (grams, pounds, whatever) of methane produces 44 mass units of carbon dioxide and 36 mass units of water while consuming 64 mass units of oxygen.”
http://cdiac.ornl.gov/pns/faq.html
The methane venting rise and CO2 rise is tracking exactly with the other rise in multi-year ice: http://arctic-roos.org/observations/satellite-data/sea-ice/ice-area-and-extent-in-arctic
> methane …oxygen … CO2 … water
But see: http://rabett.blogspot.com/2010/02/passing-gas.html
for more than almost anyone has ever wanted to know about the details
Methane is a transient gas in the atmosphere, while CO2 essentially accumulates in the atmosphere / ocean carbon cycle, so in the end the climate forcing from the accumulating CO2 that methane oxidizes into may be as important as the transient concentration of methane itself.
What else did you think we were worried about?
Doh!
[Response: Climate forcing from methane itself as a greenhouse gas, duh. David]