Arctic Sea Ice : Forum

AGW in general => Science => Topic started by: Csnavywx on October 09, 2013, 07:38:06 PM

Title: Possibly important paper regarding CH4
Post by: Csnavywx on October 09, 2013, 07:38:06 PM
http://www.pnas.org/content/early/2013/09/13/1309188110.abstract#corresp-1 (http://www.pnas.org/content/early/2013/09/13/1309188110.abstract#corresp-1)

If anybody has access to this paper, I would be indebted.....
Title: Re: Possibly important paper regarding CH4
Post by: JimD on October 09, 2013, 09:19:44 PM
It is too early to find a non-paywalled version as it was just published.  But Climatge Progress has an article on it that has more detail.

http://thinkprogress.org/climate/2013/10/08/2750191/petm-co2-levels-doubled-55-million-years-ago-global-temperatures-jumped/ (http://thinkprogress.org/climate/2013/10/08/2750191/petm-co2-levels-doubled-55-million-years-ago-global-temperatures-jumped/)
Title: Re: Possibly important paper regarding CH4
Post by: JimD on October 09, 2013, 09:29:44 PM
Also there is some discussion on this paper over at Real Climate in the Unforced Variations thread starting at post 119.  Gavin Schmidt indicates that this conclusion is going to be very controversial so it would not be wise at this point to base any conclusions on it.  Very controversial seldom turns out to be on the mark, but, of course, it sometimes does.  It will be interesting to see.
Title: Re: Possibly important paper regarding CH4
Post by: ccgwebmaster on October 10, 2013, 02:46:32 PM
Also there is some discussion on this paper over at Real Climate in the Unforced Variations thread starting at post 119.  Gavin Schmidt indicates that this conclusion is going to be very controversial so it would not be wise at this point to base any conclusions on it.  Very controversial seldom turns out to be on the mark, but, of course, it sometimes does.  It will be interesting to see.

Sadly, I think it's on the mark - or at least - I think a very rapid change for a true methane catastrophe is exactly what one ought to expect due to the massive front-loading of warming you get with methane.

Which would suggest if we do trigger a genuine methane catastrophe from the submarine clathrates, we should probably expect a matter of a few years at most before the effects are likely unmanageable over the majority of the planet (and a decade or two for them to be categorically unsurvivable over a majority of the currently inhabited surface).

I'd definitely be curious how they arrived at a figure of 13 years though, that's remarkable resolution for such long scale paleoclimatology - it makes Peter Wadhams estimates (from the contentious cost of arctic climate change paper which used 5GT on a range of timescales) kind of tame...

I wonder if they focussed on the most abrupt period of positive feedback and left the long tail and gradual build up at the start?
Title: Re: Possibly important paper regarding CH4
Post by: wili on October 10, 2013, 03:30:49 PM
Please note sidd's post at #128 in the discussion at RC:

 
Quote
  1)delta-O18 variations are quite strong evidence for the layers being annual

    2)The ability to temporally differentiate delta-CaCO3 and delta-C13 response is another huge argument for the layers being annual

    3)The speed of CaCO3 decrease is astonishing, ” … %CaCO3 shows a more abrupt decrease, from 6% to 1% within one layer.” Acidification occurred in an eyeblink. “Precipitous” is the term the authors use.

    4)3000 GT carbon release estimate: “Given the rapidity of the onset, magnitude of the δ13C excursion, and that the observed calcite compensation depth shoaling in deep ocean requires ∼3,000 GtC(3), two mechanisms meet these criteria: large igneous province-produced thermogenic methane (6, 7) and cometary carbon (11,12).
Title: Re: Possibly important paper regarding CH4
Post by: sidd on October 10, 2013, 08:48:07 PM
I have reproduced Fig. 3 and Fig. 4, with some small comments on the paper at

http://membrane.com/sidd/Wright-2013.html (http://membrane.com/sidd/Wright-2013.html)

sidd
Title: Re: Possibly important paper regarding CH4
Post by: ggelsrinc on October 10, 2013, 11:12:25 PM
What are the estimates of global temperatures before and after PETM?

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fupload.wikimedia.org%2Fwikipedia%2Fcommons%2F1%2F1b%2F65_Myr_Climate_Change.png&hash=a89b023ffc9907055593e394cb598c72)

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fdeforestation.geologist-1011.net%2FPhanerozoicCO2-Temperatures.png&hash=c011b6fd3761feeb212264bcd7e93a83)

22 degrees C is a Hothouse Earth. The only thing different I have seen in that report is the claim that PETM happened faster than previous estimates, but it's well known it happened quickly in geological time. The data supporting that claim was gathered in an area that had a bolide impact 20 million years after PETM (and I'm just giving approximations, because I haven't read the report). To this day, we do not know what caused the PETM and many hypotheses have been offered.

If that report has something new to offer in explaining the PETM, I'd be glad to read it. Put a request in for the report and this site has the means to do it!

The world around the PETM was very different than today. Before jumping into a bunker, you might want to check the facts.
Title: Re: Possibly important paper regarding CH4
Post by: idunno on October 11, 2013, 12:38:30 AM
as i find this too distressing to actually read, i"m only guessing that this is a link to the full paper

http://thingsbreak.files.wordpress.com/2013/10/evidence-for-a-rapid-release-of-carbon-at-the-paleocene-eocene-thermal-maximum.pdf (http://thingsbreak.files.wordpress.com/2013/10/evidence-for-a-rapid-release-of-carbon-at-the-paleocene-eocene-thermal-maximum.pdf)

but you still can't make me read it

cheers

;)
Title: Re: Possibly important paper regarding CH4
Post by: ggelsrinc on October 11, 2013, 03:54:24 AM
as i find this too distressing to actually read, i"m only guessing that this is a link to the full paper

http://thingsbreak.files.wordpress.com/2013/10/evidence-for-a-rapid-release-of-carbon-at-the-paleocene-eocene-thermal-maximum.pdf (http://thingsbreak.files.wordpress.com/2013/10/evidence-for-a-rapid-release-of-carbon-at-the-paleocene-eocene-thermal-maximum.pdf)

but you still can't make me read it

cheers

;)

Thank you for posting the report.

According to what you said, I'd say don't read it, because it appears to be science in reverse. Let's consider the first sentence:

Quote
The Paleocene/Eocene thermal maximum (PETM) and associated
carbon isotope excursion (CIE) are often touted as the best geologic
analog for the current anthropogenic rise in pCO2.

Source: http://thingsbreak.files.wordpress.com/2013/10/evidence-for-a-rapid-release-of-carbon-at-the-paleocene-eocene-thermal-maximum.pdf (http://thingsbreak.files.wordpress.com/2013/10/evidence-for-a-rapid-release-of-carbon-at-the-paleocene-eocene-thermal-maximum.pdf)

Their method of dating involves carbon isotopes and biostratigraphy. Their claims are so unscientific that it leads me to believe the report is bait for people who honestly believe in global warming.

Oddly enough, I happen to have spent nearly all my life living and collecting fossils in the areas they tested. I didn't find any science in that report we don't already know and it's written in a very unscientific style.

The area under my feet as I type was in the Atlantic Ocean at the PETM. There is evidence all over the world that something caused the carbon isotope ratio to quickly change, so that isn't anything new. Finding that carbon isotope change layer and accurately dating it with biostratigraphy is impossible. Someone who has taken courses in Invertebrate Paleontology would know that.
Title: Re: Possibly important paper regarding CH4
Post by: wili on October 11, 2013, 05:00:58 AM
My friend ggelsrinc seems to be quite ready to proclaim quite definitively quite frequently that articles that have gone through peer review to be accepted into major scientific publications are absolutely known to him to be utterly worthless pieces of crap. Often, this opinion seem to stem from the most bizarre types of observations--recently because a scientific paper failed to state clearly something he already knew, he decided the paper was garbage.

Just saying, that it might just be possible that, just because our beloved colleague g thinks that something is utter crap, does not in fact mean that it has been definitively proved to be in fact utterly worthless crap. A

All I can add is:

http://en.wikipedia.org/wiki/Dunning%E2%80%93Kruger_effect (http://en.wikipedia.org/wiki/Dunning%E2%80%93Kruger_effect)
Title: Re: Possibly important paper regarding CH4
Post by: ggelsrinc on October 11, 2013, 05:56:39 AM
My friend ggelsrinc seems to be quite ready to proclaim quite definitively quite frequently that articles that have gone through peer review to be accepted into major scientific publications are absolutely known to him to be utterly worthless pieces of crap. Often, this opinion seem to stem from the most bizarre types of observations--recently because a scientific paper failed to state clearly something he already knew, he decided the paper was garbage.

Just saying, that it might just be possible that, just because our beloved colleague g thinks that something is utter crap, does not in fact mean that it has been definitively proved to be in fact utterly worthless crap. A

All I can add is:

http://en.wikipedia.org/wiki/Dunning%E2%80%93Kruger_effect (http://en.wikipedia.org/wiki/Dunning%E2%80%93Kruger_effect)

I'm not the subject of this thread and neither are you.

Do you know what a wild goose chase means?

If my analysis of that report is it's hurting the efforts of climate scientists, people who believe in global warming and that offends you, then that's just too bad.

Do you have anything to say about the actual science involved or the report?

I think the report is bait to make people who believe in global warming look foolish, but it's just my opinion.
Title: Re: Possibly important paper regarding CH4
Post by: sidd on October 11, 2013, 09:00:32 AM
May I suggest that people actually read the paper ? I see the corresponding author is

jdwright@rci.rutgers.edu

or you can look up the rutgers fone book and call him ?

I am certain he would be glad to send you a copy.

Or you could ask a librarian.

Just sayin, read the thing and then we can talk about it instead of people screamin at each other ...

sidd
Title: Re: Possibly important paper regarding CH4
Post by: johnm33 on October 11, 2013, 12:42:57 PM
Interesting evaluation of peer review system http://phys.org/news/2013-10-scientists-bad-peers-published.html (http://phys.org/news/2013-10-scientists-bad-peers-published.html) just saying.
Title: Re: Possibly important paper regarding CH4
Post by: wili on October 11, 2013, 06:54:18 PM
Good idea, sidd. Let's do our homework, folks.
Title: Re: Possibly important paper regarding CH4
Post by: sidd on October 11, 2013, 07:27:28 PM
The paper on the peer review system examines only biomed papers. As such thei results cannot be applied to fields such as, say, fizix, or... dare I say ... climate science ...
Title: Re: Possibly important paper regarding CH4
Post by: ccgwebmaster on October 11, 2013, 08:56:39 PM
as i find this too distressing to actually read, i"m only guessing that this is a link to the full paper

Thanks very much - greatly appreciated.

I've had a glance at it - only a glance, as it's clear I need to set aside some proper time (not just for the paper, but to re-examine the PETM and various theories put in the context the paper suggests).

It's interesting that they don't include submarine clathrates in the conclusion as a postulated abrupt source of methane. My understanding is that extraterrestial impact doesn't look very convincing when applied to PETM and I'm a little skeptical about volcanic activity releasing large amounts of methane from fields accompanying coal and gas (if I understand what they wrote correctly). While it does resonate a bit with the Siberian traps driving the end Permian (in the first stage at least), I struggle to understand how one could release such a massive amount of methane so abruptly in this way.

It's also a brand new concept to me though, and hence requires examination.

My leaning is towards submarine clathrates as a source for the abrupt warming, provided that candidates exist for providing enough forcing to reach the threshold at which they can be triggered (as they don't just happen on their own) and that it seems likely that there was a sufficient quantity of shallow water clathrates at the time of the PETM - somewhat of an important if - as the ESAS presumably cannot be expected to have existed indefinitely back into the past in the current form - and the starting climate was clearly very different.

I can only assume that submarine clathrates weren't postulated as conventional wisdom appears to still be that they require thousands of years to release - a viewpoint that seems rather flawed in the context of shallow water clathrates deposits.

Obviously deeper water clathrates should be far harder to release owing to the increasing role played by pressure stabilisation and the timescales required to significantly warm the deeper ocean (although a glance at a Wikipedia article on PETM suggested some speculation about abrupt changes to thermohaline circulation - that sounds quite speculative in this context).

If one was going to take a precautionary outlook, I think one must assume that there is at least some risk that whatever happened during the PETM can happen today given that it and the PETM are our best paleoclimatic analogs for the rate at which we are changing things (and still generally inadequate).

Too many people are too quick to want to believe that these things cannot happen, and take a lack of definitive evidence either way to support the position they want to hold. Hopefully more will be forthcoming from Shakhova and Semiletov to determine the reasons they think abrupt release is possible.

Personally, I favour the inherent buoyancy of clathrate deposits combined with mechanical abrasion as the pressurised gas front starts to leak through the containing silt or permafrost as a logical mechanism to transport heat into the seabed deeper and faster than simple thermal conduction. Futhermore I think people too often concentrate on deep water clathrates and ignore the proven presence of large amounts of shallow water clathrates (this appeared to be a key theme in the attacks on the Wadhams paper recently - many people - even informed people - didn't seem to think the clathrates observed in the ESAS expeditions even existed!).

Another argument I would put against the cometary carbon theory is that it seems incredible to me that carbon dioxide could cause such a rapid rate of warming alone? Can anyone shed light on that? The current rate of warming due to the thermal budget imbalance of the planet is around 0.1C per decade, isn't it?

If the rapid injection of large volumes of carbon dioxide can give warming such a dramatic kick, that in itself is potentially rather serious considering the large amounts of carbon that could be rapidly added as the Amazon basin dies/burns - not to mention numerous other sources of potentially fairly rapid carbon feedbacks.
Title: Re: Possibly important paper regarding CH4
Post by: ggelsrinc on October 11, 2013, 09:01:59 PM
Good idea, sidd. Let's do our homework, folks.

Yes, 18 and a half hours later after the link for the report was posted is as good of time as any to read the report. It's only 6 pages long with pictures and footnotes.

I'm interested in discussing the report and not someone who has read or not read the report.

I don't believe the report is without merit, but I particularly don't like the way it connected it's findings with our present global warming problems. The simple reason is, it can't be proven and makes the report look biased. I would encourage all scientists to voice their opinions on global warming, but don't do it in scientific reports, unless the science is climate science.

We live in a world that is very different than the past. I think the evidence of something rapidly changing the CIE during PETM is overwhelming, but we don't know how it was done. We ought to know how our present world's problems was done.
Title: Re: Possibly important paper regarding CH4
Post by: mati on October 12, 2013, 12:52:50 AM
I ran across these 3 articles a few years ago.   They are still relevant:

http://www.geolsoc.org.uk/Geoscientist/Archive/June-2008/The-Proof-in-the-Puddingstone (http://www.geolsoc.org.uk/Geoscientist/Archive/June-2008/The-Proof-in-the-Puddingstone)

Title: Re: Possibly important paper regarding CH4
Post by: ggelsrinc on October 12, 2013, 01:00:19 AM
From what I know, this present day shallow methane hydrates situation is a product of massive glaciation which wasn't present before PETM and many years later. There is no evidence on Earth of massive glaciation during that time. It was a Hothouse Earth with a primitive Arctic Ocean connected in other ways like the Turgai straight. I haven't found data supporting a primitive Arctic Ocean and Pacific connection during PETM.

There is plenty of evidence something very drastic happened and it definitely involved rapid changes in carbon isotope ratios. Science considers all possibilities and that's why it thinks up possible circumstances or scenarios that could change such isotopic ratios. The main candidates are reasonable.

Basing something on a known unknown isn't reasonable. 

 
Title: Re: Possibly important paper regarding CH4
Post by: wili on October 12, 2013, 01:45:27 AM
Because some of the present day subsea clathrates were formed as a product of glaciation does not mean that this is the only way they could be formed. It's even been proposed that clathrates have formed on Mars where, as far as I've heard, there have been no major glaciations.  :)

http://en.wikipedia.org/wiki/Carbon_dioxide_clathrate (http://en.wikipedia.org/wiki/Carbon_dioxide_clathrate)
Title: Re: Possibly important paper regarding CH4
Post by: ggelsrinc on October 12, 2013, 02:06:31 AM
Because some of the present day subsea clathrates were formed as a product of glaciation does not mean that this is the only way they could be formed. It's even been proposed that clathrates have formed on Mars where, as far as I've heard, there have been no major glaciations.  :)

http://en.wikipedia.org/wiki/Carbon_dioxide_clathrate (http://en.wikipedia.org/wiki/Carbon_dioxide_clathrate)

Is there any evidence Physics has changed in the last 55 or so million years? Methane hydrate exists in a particular temperature/pressure zone, usually in the deep ocean. For it to exist at less depth requires massive glaciation and rebound, based on what I know. Let's just deal with Earth and it's past at the moment!
Title: Re: Possibly important paper regarding CH4
Post by: sidd on October 12, 2013, 07:08:23 AM

Mr ggelsrinc writes:
"I particularly don't like the way it connected it's findings with our present global warming problems."

Sorry I don't understand. The last sentence of the Wright paper is

"Finally, the revised timescale for the rate of carbon release at the onset of the PETM limits its usefulness as an analog for our current anthropogenic release."

I read that as explicitly disavowing a connection. PETM  depleted c13 carbon release was much faster than today, according to this paper

sidd.

Title: Re: Possibly important paper regarding CH4
Post by: ccgwebmaster on October 12, 2013, 08:17:55 AM
I read that as explicitly disavowing a connection. PETM  depleted c13 carbon release was much faster than today, according to this paper

One wonders if they also shied away from including any mention of submarine clathrates to distance themselves from all that controversy. I can't see how that's really a worse candidate than either of the ones advanced (all of which would require additional evidence to support).

While it would seem to invalidate comparisons with the PETM in the modern day analog - I think it ought to be setting off alarm bells regardless - that the earth's climate should apparently be capable of changing by so much in so little a time - and we don't fully understand how.

It isn't that the potential for abrupt large peturbations isn't understood aka the impact that appears to have done for the dinosaurs - but that a greenhouse event (rather different) should be capable of happening globally (as opposed to in specific regions where abrupt climate change has been documented in situations such as the Younger Dryas) so rapidly.

That's a rather unsettling notion - a much bigger deal than an abrupt regional change (which could be serious enough).
Title: Re: Possibly important paper regarding CH4
Post by: ggelsrinc on October 12, 2013, 08:25:24 AM

Mr ggelsrinc writes:
"I particularly don't like the way it connected it's findings with our present global warming problems."

Sorry I don't understand. The last sentence of the Wright paper is

"Finally, the revised timescale for the rate of carbon release at the onset of the PETM limits its usefulness as an analog for our current anthropogenic release."

I read that as explicitly disavowing a connection. PETM  depleted c13 carbon release was much faster than today, according to this paper

sidd.


My point was very simple and I quoted the first sentence. It doesn't make good scientific sense to even mention the political connection of PETM to global warming. The connection has nothing to do with science and is merely speculation. Of course, changes in major greenhouse gases, even in what can be called geologic time, will affect the Earth. They certainly will affect the Earth if an event happens quickly.

The CIE event could have been instantaneous or over a relatively short period of time, based on many studies. That suggests bolide impact or volcanic activity. There are other studies using other isotopes that highly suggest volcanic activity, but it isn't conclusive. There are also studies showing more than one event.

PETM is a known unknown and I think it's foolish to embrace an example that can't be proven, thinking you are making a point, pro or con about climate change. If someone can't see evidence of global warming, because of increases in CO2, how is it possible to see it during PETM? Something obviously happened to change CIE, but we don't know what it was.

I understand what I know of the history of both sides in the climate debate using PETM and trying to make their cases. The uncertainties make it a poor example.
Title: Re: Possibly important paper regarding CH4
Post by: wili on October 12, 2013, 07:03:32 PM
Methane can arise from a wide range of processes. Whenever it ends up at pressures and temperatures that lead to methane formation, that will happen.

Your argument is basically:

There are clathrates under the Arctic Ocean
We know that some of them were formed through the process of glaciation
Therefore all clathrates everywhere have always been only formed through glaciation

Kinda like:

Fluffy is a cat
Fluffy is white
Therefore all cats are white

I don't know all the science, and neither do you. But let's at least try to avoid major false syllogisms.
Title: Re: Possibly important paper regarding CH4
Post by: ggelsrinc on October 12, 2013, 09:28:18 PM
Methane can arise from a wide range of processes. Whenever it ends up at pressures and temperatures that lead to methane formation, that will happen.

Your argument is basically:

There are clathrates under the Arctic Ocean
We know that some of them were formed through the process of glaciation
Therefore all clathrates everywhere have always been only formed through glaciation

Kinda like:

Fluffy is a cat
Fluffy is white
Therefore all cats are white

I don't know all the science, and neither do you. But let's at least try to avoid major false syllogisms.

I've been stating facts and you have been arguing your nonsense. Now you're taking my statement about permafrost from another thread and bringing it into this conversation about the PETM.

Explain in detail how methane can arise from a wide range of processes has anything to do with this discussion!
Title: Re: Possibly important paper regarding CH4
Post by: sidd on October 13, 2013, 05:18:18 AM
Mr. ggelsrinc writes:

"My point was very simple and I quoted the first sentence."

To refresh reader's memories, the first sentence of the paper is:
"The Paleocene/Eocene thermal maximum (PETM) and associated carbon isotope excursion (CIE) are often touted as the best geologic analog for the current anthropogenic rise in pCO2.""

Mr. ggelsrinc continues:

"It doesn't make good scientific sense to even mention the political connection of PETM to global warming. The connection has nothing to do with science and is merely speculation."

I think you misread. I think the authors the authors agree with you. The second sentence of the paper continues:
"However, a causal mechanism for the PETM CIE remains unidentified ... " and the final sentence is an explicit disavowal of present day parallel to PETM.

I read the paper as a warning _not_ to compare PETM with present day.

I would rather talk about the science in the paper as written, and not editorialize about possibly better wording, so I will drop this particular subthread.

sidd
Title: Re: Possibly important paper regarding CH4
Post by: sidd on October 13, 2013, 07:01:02 AM
Mr ccgwebmaster writes:

"One wonders if they also shied away from including any mention of submarine clathrates to distance themselves from all that controversy. I can't see how that's really a worse candidate than either of the ones advanced (all of which would require additional evidence to support)."

There is a post on realclimate by David Archer:

http://www.realclimate.org/index.php/archives/2012/01/much-ado-about-methane/#ITEM-10412-6 (http://www.realclimate.org/index.php/archives/2012/01/much-ado-about-methane/#ITEM-10412-6)

where he explains some reasons for thinking that methane clathrate was not the sole cause of PETM.

First, the carbon release was larger than thought. He cites a paper by Pagani which estimates 5900 Gton carbon as the minimum carbon release at PETM. This is almost twice the new estimate by Wright, which may be due to the method used to reconcile shallow and deep ocean records in Wright, Fig 4., which I have reproduced at the link I posted earlier:

http://membrane.com/sidd/Wright-2013.html (http://membrane.com/sidd/Wright-2013.html)

Second, Pagani goes on to state that the Paleocene clathrate deposits were small, refers to a paper by Buffett and Archer (!) describing a model to estimate clathrate reservoirs. Briefly, the temperature of the ocean was higher in the Paleocene than today, leading to a smaller gas hydrate stability zone.

But, of course, things are never so simple. The first, and more minor point, is that the Buffett and Archer paper refers a model by Dickens (a nice paper, conceptually quite simple) for methane release from clathrate, which, oddly enough,  winds up with an estimate closer to Wright than Pagani of 2600GTon carbon escaping from seabed at PETM.

 (I see that the Buffett and the Dickens paper seem to be freely available through a search at scholar.google.com )

Second, and more important to my mind, the Buffett and Archer model leaves an important escape hatch, that a clathrate reservoir of the requisite size could have existed _if the Paleocene ocean were anoxic_

And that leads me back to the work of Kidder and Worsley, about which I have posted in a different thread.

I could go on, but I have probably bored most readers already. I do hope, though, that this sheds some light on the availability or lack thereof, of sufficient methane clathrate reservoirs as a trigger for PETM. Personally, I think that methane was _one_cause, because biogenic methane clathrate is one of the most isotopically light reservoirs around, so it would take less methane clathrate release to give the measured carbon isotope excursion at the PETM.

sidd
Title: Re: Possibly important paper regarding CH4
Post by: sidd on October 13, 2013, 07:07:58 AM
Mr. ccgwebmaster:

While pontificating on clathrate reservoirs, I entirely forgot to mention that I fully agree with your statement immediately following the one I quoted:

"While it would seem to invalidate comparisons with the PETM in the modern day analog - I think it ought to be setting off alarm bells regardless - that the earth's climate should apparently be capable of changing by so much in so little a time - and we don't fully understand how ."

The speed of change depicted in the Wright paper is unnerving. I did not think it could happen so fast.

sidd
Title: Re: Possibly important paper regarding CH4
Post by: ChrisReynolds on October 13, 2013, 09:29:17 AM
It is looking hard to see how the d13C excursion could have been due to methane, however it is equally hard to see how vulcanism could be the culprit, even an incursion of magma into coal beds would produce an initial increase of 13C depleted CH4. The asteroid/comet impact idea is interesting, but where are the other 13C depletion events due to asteroid/comet impacts?

But the basic problem is that figure 3 and text implies an instantaneous introduction of C13 light carbon. Although the high sedimentation rates (and analogy with the Amazon delta) implies river run off and shallow seas, so I find the idea that it needs to be an instant release followed by a gradual (decadal) downward percolation of the 13C light carbon to be unlikely.

But if it is CH4 from marine clathrates that means 1,200 GtC would have to be released to the atmosphere within 2 decades. That's hard to believe as well.
Title: Re: Possibly important paper regarding CH4
Post by: ChrisReynolds on October 13, 2013, 10:20:11 AM
Actually, I've just read Revell/Suess 1957 section on rate of exhange of CO2 between atmospher and Ocean.
http://www.odlt.org/dcd/docs/Revelle-Suess1957.pdf (http://www.odlt.org/dcd/docs/Revelle-Suess1957.pdf)

They note that their estimate was similar to that of Bohr who worked in a lab using stirred liquids. So I think the results of Wright and Schaller do support an instantaneous injection of isotopically light carbon, with gradual infiltration of the isotopically light carbon into sediments forming the core consdered.

That implies that the excursion of 13C and associated warming was likely due to asteroid/comet impact, assuming their chronology argument is correct. And the only way I can see the chronology being wrong is due to some unkown longer term (than a year) climatic cycle at work in the region of study.
Title: Re: Possibly important paper regarding CH4
Post by: ccgwebmaster on October 14, 2013, 10:08:55 PM
But if it is CH4 from marine clathrates that means 1,200 GtC would have to be released to the atmosphere within 2 decades. That's hard to believe as well.

I think it's puzzling - nothing seems to be an intuitively good fit.

I still lean towards shallow water clathrates - but - that wouldn't give the whole picture, as I understand it true methane catastrophes are exceptionally rare (just one or at most two in the last quarter billion years?) and something would be required to have pushed the earth system to that threshold.

For the end Permian the most convincing theory I've read is that the long running eruption of the Siberian traps releasing carbon dioxide did that - warming the planet by around 5C so that it would reach a point where the methane became capable of positive feedback. However, the timescale isn't constrained low enough there to give any guide as to abruptness or the exact sourcing of the methane (ie shallow water vs deeper water).

Is there any such candidates for the PETM? Any initial peturbations of large enough magnitude to trigger abrupt methane release (which if started enough to become self sustaining I suspect could become relatively abrupt - though I'd agree it still seems an incredible release in such a timescale)?

Alternatively is there any way their findings can be applied only to a specific region (ie where they took samples)? Which is to say one would be looking at an abrupt regional change which seem to be less unusual?
Title: Re: Possibly important paper regarding CH4
Post by: ChrisReynolds on October 14, 2013, 10:25:39 PM
I've just blogged on this, been pondering all day.

It's worse than an emission over decades, their main figure shows CaCO3 dropping within less than 4 years - i.e. the emission would have to have happened within 4 years.

The problem with a local emission - dissovling in the water column, is that it would surely show a more rapid crash in 13C. The releationship between 13C and CaCO3 does suggest an atmospheric source.

I keep going back to questioning whether their assesment of the layers in the clay as being annual is wrong, but I can't see how. For the layers to be related to a periodic climate system in that region at that time (like the AMO) would stretch out the timescale and make it all more believable/understandable.
Title: Re: Possibly important paper regarding CH4
Post by: wili on October 15, 2013, 03:42:18 AM
It does seem like an unbelievably rapid change, whatever the source.

If it is not in violation of the rules, would you mind providing a link to the blog post you mentioned?
Title: Re: Possibly important paper regarding CH4
Post by: sidd on October 15, 2013, 05:44:03 AM
Kidder and Worsley ascribe PETM to North Atlantic Igneous Province, and note limited anoxia and euxinia in ocean, and delta-N15 excursion, freely available.

GSA Today, v. 22, no. 2, doi: 10.1130/G131A.1

so perhaps enuf clathrate deposits were around, as Buffett and Archer admit could be the case with anoxic ocean ...

i do wish Wright or associates do the N-15 isotope assay as well, will tell a lot

i dislike the comet idea, smacks too much of deus ex machina

sidd
Title: Re: Possibly important paper regarding CH4
Post by: ggelsrinc on October 15, 2013, 06:46:55 AM
Kidder and Worsley ascribe PETM to North Atlantic Igneous Province, and note limited anoxia and euxinia in ocean, and delta-N15 excursion, freely available.

GSA Today, v. 22, no. 2, doi: 10.1130/G131A.1

so perhaps enuf clathrate deposits were around, as Buffett and Archer admit could be the case with anoxic ocean ...

i do wish Wright or associates do the N-15 isotope assay as well, will tell a lot

i dislike the comet idea, smacks too much of deus ex machina

sidd

Is that so? Can you explain it?
Title: Re: Possibly important paper regarding CH4
Post by: ChrisReynolds on October 15, 2013, 07:53:14 AM
Wili,

It's here:
http://dosbat.blogspot.co.uk/2013/10/mid-monthly-miscellenea-october.html (http://dosbat.blogspot.co.uk/2013/10/mid-monthly-miscellenea-october.html)

Sidd,

Think about the time progresss of such an invasion of magma, would it really release 3000Gt C in around 4 years?
Title: Re: Possibly important paper regarding CH4
Post by: Pmt111500 on October 15, 2013, 09:52:24 AM
Craters formed during Palaeocene:
http://en.wikipedia.org/wiki/Marquez_crater (http://en.wikipedia.org/wiki/Marquez_crater) ø12,7km
http://en.wikipedia.org/wiki/Connolly_Basin_crater (http://en.wikipedia.org/wiki/Connolly_Basin_crater) ø9km
http://en.wikipedia.org/wiki/Jabel_Waqf_as_Suwwan_crater (http://en.wikipedia.org/wiki/Jabel_Waqf_as_Suwwan_crater) ø5,5km

then there's the pretty accurately dated to 50My ago (thus not fitting remnant for PETM)
http://en.wikipedia.org/wiki/Montagnais_crater (http://en.wikipedia.org/wiki/Montagnais_crater) ø45 km

of course there might be a marine hit that we know nothing about, of the deux ex machina type. or just a huge cloud of shooting stars of carbonaceous material (well this would probably be of cometary origin too, f.e. a huge Kreutz sungrazer on a collision course but the sun shattered it & melted all of the binding ice.)

oops, this is a methane thread. I think there's methane ice on comets.
Title: Re: Possibly important paper regarding CH4
Post by: wili on October 15, 2013, 11:45:16 AM
Thanks, CR. That was a very lucid presentation. I still think that the paper suggests that things can happen on our little earth that are beyond what we can understand. As neven likes to say about the Arctic, it always surprises.

It seems to me that a major earthquake could potentially release a lot of methane if fissures opened up along coasts where a lot had been sequestered. But short of that, as you point out, things are likely to unfold more slowly than this apparent event suggests. And yes, even Shakhova' estimates look tame compared to this amount and rate. But then, though many assume she was pushing the envelope a bit, it is possible that she was being conservative in that number, too, or just underestimating.

Anyway, thanks again for the lucid treatment of the article. And congrats again on getting this years melt season so right so far ahead of most of the rest of us.
Title: Re: Possibly important paper regarding CH4
Post by: ccgwebmaster on October 15, 2013, 03:38:57 PM
i dislike the comet idea, smacks too much of deus ex machina

sidd

Is that so? Can you explain it?

If you want to add the carbon as cometary carbon, it's an awfully large and specific one. For 3000 GTC you're looking at 1153 billion m^3 volume taking density 2.6 tonnes/m^3 if it's pure carbon - giving you a perfect sphere 13 km in diameter. The impactor that wiped out the dinosaurs is thought to have been around 10km in diameter, for comparison.

Does anyone have any idea what the purity of said hypothetical comet would be? Or if there is any evidence supporting the addition of significant amounts of carbon into the earth system by this mechanism (even at a smaller scale)? There is plenty of evidence for impacts in general - and it seems reasonable to support they would once have been quite frequent, the one that nobbled the dinosaurs being remarkable primarily for being later in earth history.

I have trouble understanding how one could drop something that big onto the planet without leaving a much stronger signature behind. There seems to be plenty of evidence that it was an asteroid impact that did for the dinosaurs. A whole host of other effects come with an impact whether it's land or sea.

It's worth noting that impacts do happen anyway and the waters can be muddy. Impact has been put forward as a driver of the end Permian extinction before, and according to a rather good documentary I watched about it a few months back - there is evidence of shocked quartz around that time - just nowhere near enough in quantity and distribution to support an impact as the key driver of the extinction. Accordingly, I don't think it's safe to assume just because there is some impact signature that it is the key driver here - without more solid evidence.

So if you want to go with cometary carbon can you construct a theory that seems plausible that fits the information available? (preferably with a < 100% purity comet, unless one is going to suggest a large diamond fell from the sky)
Title: Re: Possibly important paper regarding CH4
Post by: ggelsrinc on October 15, 2013, 04:42:40 PM
A comet is a more plausible explanation for the CIE during PETM than shallow water methane clathrates. Methane clathrates are a possibility for the CIE, but not the shallow water variety.

Speaking of diamonds, a large kimberlite field in Canada dates to that period.   
Title: Re: Possibly important paper regarding CH4
Post by: ccgwebmaster on October 15, 2013, 05:00:28 PM
It seems to me that a major earthquake could potentially release a lot of methane if fissures opened up along coasts where a lot had been sequestered. But short of that, as you point out, things are likely to unfold more slowly than this apparent event suggests. And yes, even Shakhova' estimates look tame compared to this amount and rate. But then, though many assume she was pushing the envelope a bit, it is possible that she was being conservative in that number, too, or just underestimating.

Much as I favour submarine clathates as a driver of abrupt climate change (not necessarily catastrophic by earth system standards in most cases), I don't think you can get to where you need to be to fit the paper without quite a bit of explanation.

When you say a major earthquake could theoretically release a lot of methane - perhaps - but you need to consider the figures. The amounts required in total within those few years are (for example) a very significant portion of the total amount in the ESAS (or virtually all of it) and only a fraction of the methane present exists as pressurised free gas. The probability of an earthquake releasing amounts on the scale required seems to be essentially nil.

I think to get clathrates involved on a short timescale, deep water clathrates can be ruled out unless one can propose an extremely rapid way to get the necessary heat to destabilise them.

Even with shallow water clathrates, I can't see how they could act in such a short timescale. So far in the ESS we've seen that the permafrost is thawing on the seafloor and that the seafloor is warming. Localised emissions of methane appear to have grown and be growing and I personally think Shakhova is on to something with respect to the risks of a large release. The more I think about it though, the more I think it seems impossible to do it as fast as this paper requires.

To start to release the methane from the clathrates and sea floor, one must first destabilise the containment and get heat down to them. That much appears to have happened today (some of it over thousands of years, some of it as a result of current climate change - earlier sea ice retreat, sea ice retreat where it previously didn't, warmer water run off from land, etc). The existence of massive craters in various places on the seabed and a certain amount of thought make it seem plausible to me that abrupt releases are possible. I don't think the argument about it taking a very long time to move heat down into the sediments automatically holds once the process properly starts.

However:

1. True methane catastrophes seem exceptionally rare (and possibly require the involvement of deep water clathrates, which cannot proceed abruptly in human terms), limited now to one promising example (end Permian). Methane does however seem significant - generally moving with temperature and carbon dioxide paleoclimatically (does anyone have good information on what mechanisms are thought to cause this, besides shallow clathrates?).

2. Even the very worst case scenarios one can construct around shallow clathrates cannot act fast enough. If Shakhova were proved right that an abrupt release of 50GT from ESAS on a decadal timescale is possible - the worst case concern would be that the warming implied by that would lead to the onset of a positive feedback causing subsequent larger events (the best case is a more limited pulse of above trend warming - still very serious in human terms). That warming would still take time. Therefore even if there was a very abrupt period during such a positive feedback - the time it takes to build up should still be clearly present in the record - which doesn't seem to be the case here.

I just can't see any way to move that amount of methane from clathrates in that timescale, at least not using any mechanism that seems logical in the context of Arctic climate change and the ESAS.

You also still need to move the earth system to a point whereby the clathrates can destabilise in a big way. For the end Permian that seems to be tens of thousands of years of eruption from the Siberian traps - in the modern era - it's the injection of carbon dioxide by human activity - what would it be for the PETM?

What does that leave? Earthquakes ruled out, self reinforcing feedback ruled out - what else is there?

My biggest problem with this paper is that as far as I can follow it (a little too technical for me without spending a lot of time looking things up), it seems to suggest the change was global. That would make it - if true - something rather new - quite different from abrupt and major regional changes such as the Younger Dryas.

So for a methane clathrate based theory - is there any way to release such massive volumes in such a short timescale, without an obvious escalation previously?
Title: Re: Possibly important paper regarding CH4
Post by: ccgwebmaster on October 15, 2013, 05:14:52 PM
Kidder and Worsley ascribe PETM to North Atlantic Igneous Province, and note limited anoxia and euxinia in ocean, and delta-N15 excursion, freely available.

GSA Today, v. 22, no. 2, doi: 10.1130/G131A.1

Is that this? (I need to read it properly, I'm starting to feel as though I'm wallowing in ignorance in this thread)
http://www.geosociety.org/gsatoday/archive/22/2/article/i1052-5173-22-2-4.htm (http://www.geosociety.org/gsatoday/archive/22/2/article/i1052-5173-22-2-4.htm)

so perhaps enuf clathrate deposits were around, as Buffett and Archer admit could be the case with anoxic ocean ...

But how can one get them out fast enough?

Another thing that's bugging me a bit - if there were such a large injection of greenhouse gas, would the Earth reach equilibrium within those 13 years? Or should there be a long tail of further warming? How fast can the planetary energy budget essentially balance for large and abrupt greenhouse gas peturbations? Wouldn't such a large and rapid peturbation likely trigger other slower feedbacks in the system that should be detectable? Are the conclusions the paper is reported as stating (eg 5C in 13 years) even possible globally?
Title: Re: Possibly important paper regarding CH4
Post by: wili on October 15, 2013, 05:24:10 PM
Nice summary of the conundrums, ccg. Again, the main takeaway I get from this is that it looks like the earth has some potentially very sudden catastrophic surprises up her sleeve that we can't fully grok at this point.

It should stand as a reminder of our ultimate ignorance of what can and has happened in the earth's history and what might happen. As Peter Ward pointed out, we dealing more with an occasionally child-massacring monster (Medea) than with a reliably warm, cuddly Earth Mama (Gaia), and this becomes ever more clear the more one looks at the (relatively and in this case absolutely) sudden and catastrophic events that have occurred over its history.

Or, someone might come along and show conclusively how the authors of this work got something very, very wrong.
Title: Re: Possibly important paper regarding CH4
Post by: ggelsrinc on October 15, 2013, 06:31:32 PM
http://www.geosociety.org/gsatoday/archive/22/2/pdf/i1052-5173-22-2-4.pdf (http://www.geosociety.org/gsatoday/archive/22/2/pdf/i1052-5173-22-2-4.pdf)
Title: Re: Possibly important paper regarding CH4
Post by: ChrisReynolds on October 15, 2013, 09:57:47 PM
Ccgwebmaster - you get it.

A 1200Gt (biogenic methane) or 3000Gt (thermogenic methane) pulse in a few years (up to 4 by my reckoning) is verging on the inherently improbable. And as you've calculated, an asteroid/comet sufficient to deliver that much carbon would have caused a mass extinction at least as great as the KT impact.

And I'm sorry to those who are still clinging on to methane hydrates, you need to have a mechanism that can deliver all the methane in a large region of ocean clathrates (100s of metres deep) into the atmosphere within a few years. It's not feasible, it really isn't.

If there is something wrong with this paper it's most likely in the timing part, IMO.

Out of interest, and just for fun, David Archer has a page of models, they're set up for now, not the PETM.
http://climatemodels.uchicago.edu/ (http://climatemodels.uchicago.edu/)
The slugulator allows you to see what happens with a 1200Gt slug of methane.
http://climatemodels.uchicago.edu/slugulator/ (http://climatemodels.uchicago.edu/slugulator/)

The authors note that if released as CO2 this would result in 5degC GW, with slugulator (3000Gt CO2 we get around 5degC GW after 20 years (5degC is what the paleo data indicates happened). If released as 1200Gt CH4 we get 7 degC GW after 20 years, which falls off rapidly. to be replaced by warming from CO2.
Title: Re: Possibly important paper regarding CH4
Post by: ggelsrinc on October 15, 2013, 10:45:49 PM
IIRC, samples were taken from 7 locations. The names of some of those locations are somewhat vague, but they aren't vague to someone who has spent nearly his whole life living in that area. The New Jersey sites are easy to find, just locate Millville and go from there. Clayton is west of the capital city of Dover, Delaware and South Dover Bridge has to be on the eastern shore of Maryland, because they said it was in Maryland.

I'm not sure exactly how you came up with that assessment of their time scale or how they did, but I can't imagine how accurately dating something 55.8 million years ago so accurately in years is done. It falls into a category of things that aren't impossible, but are highly unlikely.

Just the accurate dating of something that happened so long ago would be a major scientific accomplishment. In doing such a feat, I wouldn't bookend my scientific report with their first and last sentences. I'd have the sense to know what a marvelous benchmark was discovered. 
Title: Re: Possibly important paper regarding CH4
Post by: ccgwebmaster on October 15, 2013, 11:53:44 PM
If there is something wrong with this paper it's most likely in the timing part, IMO.

The thought also crossed my mind that the end Permian is a good candidate for most severe known mass extinction (beyond perhaps some very speculative theories further back in earth history) - and that rate (as well as magnitude) of climatic change is important in determining the outcome of a mass extinction (species are less able to adapt or respond to rapid changes).

My impression is that the results of the PETM mass extinction as far as we can tell were more nuanced and selective than the end Permian - and overall less severe in terms of lost biodiversity. Since nobody is suggesting quite such a rapid warming for the end Permian (and the methane clathrate theory looks reasonably strong there) I think this would tend to suggest the timing of the paper is likely to be wrong?

Otherwise introducing such a profound and rapid change into the earth system ought to have (at least looking at it as an ill informed amateur) a much more severe effect in terms of the extinction effects noted? Arguably, it ought to be the worst extinction event in the last quarter billion years if they were right (and to have wiped out virtually all life on earth)?

Another point - there were other similar events:

http://en.wikipedia.org/wiki/Eocene_Thermal_Maximum_2 (http://en.wikipedia.org/wiki/Eocene_Thermal_Maximum_2)

Quote
Other hyperthermals likely followed ETM-2 at nominally 53.6 Ma (H-2), 53.3 (I-1), 53.2 (I-2) and 52.8 Ma (informally called K, X or ETM-3).

If that suggests a repeatable mechanism (but one that started and stopped repeating within those few million years?), I think that would put further barriers in front of the cometary carbon idea if one was assuming these events had the same driver (not only do you then need multiple impacts but you would be adding massive cumulative amounts of carbon to the earths with each one - rather than just cycling what's already here?).

It seems to me most likely something else was at work - and that the timing implied conflicts with rather a lot of other stuff out there.
Title: Re: Possibly important paper regarding CH4
Post by: sidd on October 16, 2013, 04:35:40 AM
Mr. ggelsrinc writes:
"Just the accurate dating of something that happened so long ago would be a major scientific accomplishment. In doing such a feat, I wouldn't bookend my scientific report with their first and last sentences. I'd have the sense to know what a marvelous benchmark was discovered."

Agreed.

with respect to your other comment on my dislike of the comet hypothesis: 1)The iridium anomaly is small if you look at Ir/Fe ratios 2)osmium concentrations indicate increased weathering as would be expected with large igneous flow

but the main reason i dislike this, as a deus ex machina approach is that it is easy to invoke a comet because we do no understand the balance between carbon reservoirs. I find it easier to imagine a 100x100x10 km large igneous lava intrusion into a peat bed, especially because fossil carbon beds are expected to be larger in the Paleocene than today ...

but thats just me

sidd
Title: Re: Possibly important paper regarding CH4
Post by: ggelsrinc on October 16, 2013, 04:45:18 AM
PETM was an obvious CIE event, which happened while the temperatures were increasing before the Eocene Thermal Maximum. 55.8 million years is a long time, but gathering information that long ago has become much easier due to advances in dating and many other analytical methods.

The Siberian Traps:

Quote
This massive eruptive event spanned the Permian-Triassic boundary, about 250 million years ago, and is cited as a possible cause of the Permian-Triassic extinction event.[6][2] One of the major questions is whether the Siberian Traps was directly responsible, or if it was itself caused by some other larger event, such as an asteroid impact.

Source: http://en.wikipedia.org/wiki/Siberian_Traps (http://en.wikipedia.org/wiki/Siberian_Traps)

I'm not aware of scientists pointing to the cause of the Permian-Triassic extinction event being methane and I'm sure it was considered. The consensus points to coal or just volcanism, based on chemical signatures.

Carbon is common to our solar system today and what we believe was originally present when our Earth was formed should have more carbon in space. The Earth as we know it has packed away iron and carbon to the extent that it isn't like it originally was. Considering the timescales involved, bolide impacts had to play a major role. Once life began storing carbon as methane and the physics controlled it's storage, a bolide impact in an ocean would leave little trace and it's impact on the carbon cycle of that time would drastically change the climate. Enough said, bolide impacts aren't the only thing going on.

When looking back at different times, it's helpful to picture the Earth as it was during those times. In a way, it's like looking at a different world. The forces that moved those continents are very complex and powerful. We know, for example, there were periods of heavy volcanism, because we can find the rocks, but what trace of heavy seismic activity can be detected in the past? Since the Earth has so much water, what was the ability of the Earth to transfer heat around the planet at that time. Thermohaline circulation is a very powerful force, so even minor changes in currents can drastically affect an area on Earth.

In science. we observe something and try to explain what was observed. Our hypotheses are like suggestions and since the goal is knowledge to explain what was observed, even proving a suggestion wrong continues the path towards knowledge. Part of science is also how to prove something is true or false and that takes knowledge and creativity.

Getting back to the subject of this thread, I've agreed with the basic findings long before reading the report. The evidence I've seen suggests what caused PETM happened quickly and could be what is considered a spontaneous event. The evidence I've seen also suggest looking at the Atlantic Ocean or causes on land affecting the Atlantic Ocean. My objections are the two bookend sentences making the statement about connecting PETM to our current global warming problems. I also don't understand how dating with such an old event can be as accurate as claimed. My evolution in life has taught me to beware of Greeks, Geeks and Geologists bearing gifts and I don't have anything against any of those people.   

 
Title: Re: Possibly important paper regarding CH4
Post by: ChrisReynolds on October 16, 2013, 07:40:16 AM
I'm not sure exactly how you came up with that assessment of their time scale or how they did, but I can't imagine how accurately dating something 55.8 million years ago so accurately in years is done. It falls into a category of things that aren't impossible, but are highly unlikely.

Read the bloody paper!
Title: Re: Possibly important paper regarding CH4
Post by: wili on October 16, 2013, 05:42:34 PM
"Read the bloody paper!"

Good idea.

In case anyone missed it, here is the link again that idunno graciously provided up thread (but still hasn't read? Hence his handle?? '-)):

http://thingsbreak.files.wordpress.com/2013/10/evidence-for-a-rapid-release-of-carbon-at-the-paleocene-eocene-thermal-maximum.pdf (http://thingsbreak.files.wordpress.com/2013/10/evidence-for-a-rapid-release-of-carbon-at-the-paleocene-eocene-thermal-maximum.pdf)

Much of the paper is exactly devoted to how they came up with the time scale. There are regular rhythmic deposits in the cores they are looking at. The authors rule out regular changes in orbital cycles that would alter insolation patterns as being too long. The only other possibility would seem to be annual cycles.

If someone can come up with cycles likely to occur between these extremes that could possibly result in the layering they describe, that could go a long way toward explaining the apparent instantaneousness of the changes they describe and would be most welcome. But just saying one doesn't like the time scales and pontificating about the scientific method is not much help to the discussion, imho.
Title: Re: Possibly important paper regarding CH4
Post by: ggelsrinc on October 16, 2013, 07:14:13 PM
Ccgwebmaster - you get it.

A 1200Gt (biogenic methane) or 3000Gt (thermogenic methane) pulse in a few years (up to 4 by my reckoning) is verging on the inherently improbable. And as you've calculated, an asteroid/comet sufficient to deliver that much carbon would have caused a mass extinction at least as great as the KT impact.

And I'm sorry to those who are still clinging on to methane hydrates, you need to have a mechanism that can deliver all the methane in a large region of ocean clathrates (100s of metres deep) into the atmosphere within a few years. It's not feasible, it really isn't.

If there is something wrong with this paper it's most likely in the timing part, IMO.

Out of interest, and just for fun, David Archer has a page of models, they're set up for now, not the PETM.
http://climatemodels.uchicago.edu/ (http://climatemodels.uchicago.edu/)
The slugulator allows you to see what happens with a 1200Gt slug of methane.
http://climatemodels.uchicago.edu/slugulator/ (http://climatemodels.uchicago.edu/slugulator/)

The authors note that if released as CO2 this would result in 5degC GW, with slugulator (3000Gt CO2 we get around 5degC GW after 20 years (5degC is what the paleo data indicates happened). If released as 1200Gt CH4 we get 7 degC GW after 20 years, which falls off rapidly. to be replaced by warming from CO2.

Try quoting the paper!

Quote
Therefore, we interpret the 13 observed
layers through the onset of the CIE at Millville as 13 annual
cycles, and the 750 layers within the Marlboro clay at Millville as
representing 750 annual cycles.

Source: http://thingsbreak.files.wordpress.com/2013/10/evidence-for-a-rapid-release-of-carbon-at-the-paleocene-eocene-thermal-maximum.pdf (http://thingsbreak.files.wordpress.com/2013/10/evidence-for-a-rapid-release-of-carbon-at-the-paleocene-eocene-thermal-maximum.pdf)

Does it match what you posted?

Quote
A 1200Gt (biogenic methane) or 3000Gt (thermogenic methane) pulse in a few years (up to 4 by my reckoning) is verging on the inherently improbable.
Title: Re: Possibly important paper regarding CH4
Post by: ccgwebmaster on October 16, 2013, 07:23:19 PM
Much of the paper is exactly devoted to how they came up with the time scale. There are regular rhythmic deposits in the cores they are looking at. The authors rule out regular changes in orbital cycles that would alter insolation patterns as being too long. The only other possibility would seem to be annual cycles.

As - as far as my limiting understanding permits - it seems fairly robust to me. That doesn't alter the fact that it's logical to look for the weakest link here? Once you've ruled out the impossible, whatever is left - however improbable... and all that?

If someone can come up with cycles likely to occur between these extremes that could possibly result in the layering they describe, that could go a long way toward explaining the apparent instantaneousness of the changes they describe and would be most welcome. But just saying one doesn't like the time scales and pontificating about the scientific method is not much help to the discussion, imho.

I don't like the timescales simply because it's so tremendously difficult to comprehend mechanisms that can make them work - and I'm not sure if they fit other information about the PETM extinction (that is much harder to quantify of course, and I can't even do an adequate job on the mechanisms).

Incidentally, another objection I can think of about the cometary carbon idea - to counter anyone who thinks you can conveniently park something that big in an ocean:

http://en.wikipedia.org/wiki/Impact_depth (http://en.wikipedia.org/wiki/Impact_depth)

The question really is - does something that big moving at that speed act as a Newtonian impactor - or do other factors come into play?

If it does, the implication is clear - the object was minimum 13km in diameter (if pure carbon, and not impacting on land where you'd expect a big signature) - and I'm not sure where there's enough water to park it without still leaving a crater (or at least a mark)? One can play with the angle of incidence - but the more you decrease that the lower probability the event becomes.

I'd also be extremely skeptical of something that large blowing up into little pieces in the atmosphere (eg Tunguska) - the Wikipedia article above suggests the atmosphere is good for around 10m of water - against 13,000m+ of impactor?

If it arrived as lots of little pieces, it's hard to see how they'd all have been small enough to hide and still densely packed enough (in time and space) to have that level of effect.

Likewise if those few million years were characterised by multiple hyperthermals - I would've thought release of methane via volcanic activity rather fluky and likely to be a one off?

With respect to submarine clathrates - am I right to think the planet was already pretty warm and ice free at the start of this process? If so - that further undermines that argument (at least taking my view that only shallow water clathrates are likely to respond especially abruptly) as shallow water clathrates are necessarily stabilised by temperature and not pressure - and hence you require areas with the Arctic climate to retain them. While I still think shallow clathrates in the Arctic are a real threat for us today, I'm currently less and less convinced they fit the scenario described by the paper.

The challenge for anyone is to find a way to justify and explain their position - whichever possibility you favour. Personally though, it feels like something way beyond my knowledge/understanding to think of a good answer - even though it keeps nagging me as I hate unsolved problems.

Still, I've learned quite a bit trying - I stumbled over something interesting about the formation of coal that suggested so much was formed during a particular period in earth history as the organisms to digest it hadn't got going (more on the coal thread).

So there are certainly plenty of things about the earth system most of us don't know, and plenty more that nobody at all knows.

Maybe we're looking for some other unexpected quirk that could explain the hyperthermals and the speed of change - something unique to those few millions of years of earth history?
Title: Re: Possibly important paper regarding CH4
Post by: ccgwebmaster on October 16, 2013, 09:47:59 PM
Another thought just struck me - could large scale volcanic activity in conjunction with a very large coal bed (or maybe even oil field) produce this sort of signature so rapidly? Is there any reason thermogenic methane is favoured over other sequestered carbon?
Title: Re: Possibly important paper regarding CH4
Post by: ChrisReynolds on October 16, 2013, 10:24:05 PM
Ggelsrinc,

Your quote of the paper seems to have no bearing on what I think you're getting at. If you are trying to say the initiating release of depleted carbon took more than a few years, you don't get the CaCO3 excursion and argument about physical diffusion vs equilibrium impact of the depleted carbon injection.

Yes, with regards thermo/biogenic carbon, the paper does match what I've said, in the final para of the paper they state: "If released as CO2, this would be consistent with observations of an ∼5 °C global warming" having previously stated this is non-biogenic (i.e 3000Gt C)! Therefore I was fine to use 3000Gt carbon as CO2 not methane.
Title: Re: Possibly important paper regarding CH4
Post by: ChrisReynolds on October 16, 2013, 10:32:33 PM
Another thought just struck me - could large scale volcanic activity in conjunction with a very large coal bed (or maybe even oil field) produce this sort of signature so rapidly? Is there any reason thermogenic methane is favoured over other sequestered carbon?

I seriously doubt it would be that fast, from what I've read such events 'cook' the coal over centuries/millenia.

I'm as clueless as you are as to what could release so much depleted carbon so fast. And I suspect it's causing a lot of head-scratching amongst real scientists.
Title: Re: Possibly important paper regarding CH4
Post by: ggelsrinc on October 17, 2013, 12:20:27 AM
http://www.largeigneousprovinces.org/ (http://www.largeigneousprovinces.org/)

The evidence of a large volcanic event should still be around and the only event I know about is that large kimberlite field in Canada. Anything that can change the carbon isotope ratio is a possible cause. Both volcanic activity and bolide impact provide multiple sources of carbon and seem to be the most likely causes. About 20 million years later there were bolide impacts in the Chesapeake Bay, another off the coast of New Jersey and another in Russia that all date to the same period of time. Comets are known to break apart and cause multiple impacts, so they aren't easy to dismiss. Could a pressure wave cause a methane clathrates release? 

The paper cites footnotes 19 and 20 for dating. If they can really determine the onset of the CIE event to 13 years, getting an accurate date of those samples would be very helpful. It would assist in eliminating the possibility that the samples show the results of local fires, for example, like in the Amazon. Periodic droughts and monsoons need to be considered. Finding a proxy demonstrating seasonal changes within the layers would confirm their annual hypothesis and there should be something in that tropical rainforest near there that leaves (no pun intended) a seasonal signature in ocean sediments. 
Title: Re: Possibly important paper regarding CH4
Post by: ggelsrinc on October 17, 2013, 12:50:29 AM
Ggelsrinc,

Your quote of the paper seems to have no bearing on what I think you're getting at. If you are trying to say the initiating release of depleted carbon took more than a few years, you don't get the CaCO3 excursion and argument about physical diffusion vs equilibrium impact of the depleted carbon injection.

Yes, with regards thermo/biogenic carbon, the paper does match what I've said, in the final para of the paper they state: "If released as CO2, this would be consistent with observations of an ∼5 °C global warming" having previously stated this is non-biogenic (i.e 3000Gt C)! Therefore I was fine to use 3000Gt carbon as CO2 not methane.

How did you come up with a few years (up to 4 by my reckoning) when they said 13 years?
Title: Re: Possibly important paper regarding CH4
Post by: ChrisReynolds on October 17, 2013, 07:57:56 AM
The CaCO3 drop is extremely rapid (fig 3) - as they say, this is due to rapid effect of increased atmospheric concentration of CO2 taking weeks to effect the ocean column. Note that it is also present as a steep drop in all the sediment columns considered (fig 4a), and it happens just as the 13C drop starts.

The longer term decline of 13C is due to the physical infiltration of 13C atoms (in molecules) into the sea water column, as Revell/Suess find this takes about ten years.

Therefore the process was intiated by a massive increase of atmospheric carbon, taking no more than a few years, and sustained by continued high levels of atmospheric carbon. By my reading of those two graphs it looks like a period of no more than 4 years (8cm - assuming the bands in the clay are annual).
Title: Re: Possibly important paper regarding CH4
Post by: johnm33 on October 17, 2013, 11:47:47 AM
My guess as to the possible origin of such a large release would be the disturbance of a massive natural gas field by tectonic movement. Either India or Australia colliding with Asia would suffice. 
Title: Re: Possibly important paper regarding CH4
Post by: idunno on October 17, 2013, 07:11:31 PM
Or  disturbance of a large gasfield by meteor impact? Like liquor, that'd be quicker. The meteor can then be much smaller.
Title: Re: Possibly important paper regarding CH4
Post by: ggelsrinc on October 18, 2013, 02:33:03 AM
The CaCO3 drop is extremely rapid (fig 3) - as they say, this is due to rapid effect of increased atmospheric concentration of CO2 taking weeks to effect the ocean column. Note that it is also present as a steep drop in all the sediment columns considered (fig 4a), and it happens just as the 13C drop starts.

The longer term decline of 13C is due to the physical infiltration of 13C atoms (in molecules) into the sea water column, as Revell/Suess find this takes about ten years.

Therefore the process was intiated by a massive increase of atmospheric carbon, taking no more than a few years, and sustained by continued high levels of atmospheric carbon. By my reading of those two graphs it looks like a period of no more than 4 years (8cm - assuming the bands in the clay are annual).

Quote
The longer term decline of 13C is due to the physical infiltration of 13C atoms (in molecules) into the sea water column, as Revell/Suess find this takes about ten years.

I see it this way.

Quote
Deep sea carbon isotope and CaCO3 records across the Paleocene/
Eocene thermal maximum (PETM) and associated
carbon isotope excursion (CIE) (55.8 Mya) require a massive
addition of 13C-depleted carbon to the ocean–atmosphere system
in a geologically short interval of time (1–3).

Source: http://thingsbreak.files.wordpress.com/2013/10/evidence-for-a-rapid-release-of-carbon-at-the-paleocene-eocene-thermal-maximum.pdf (http://thingsbreak.files.wordpress.com/2013/10/evidence-for-a-rapid-release-of-carbon-at-the-paleocene-eocene-thermal-maximum.pdf)

bold is my addition.

Quote
Isotopes of carbon are atomic nuclei that contain six protons plus a number of neutrons (varying from 2 to 16). Carbon has two stable, naturally occurring isotopes.[11] The isotope carbon-12 (12C) forms 98.93% of the carbon on Earth, while carbon-13 (13C) forms the remaining 1.07%.[11] The concentration of 12C is further increased in biological materials because biochemical reactions discriminate against 13C.

Source: http://en.wikipedia.org/wiki/Carbon (http://en.wikipedia.org/wiki/Carbon)

In simple English, they are looking for a source of carbon that is 12C richer than what is normally found on the Earth's surface to explain the changes in isotope ratios discovered in a carbon isotope excursion (CIE) event. Think of it this way! Life on Earth prefers 12C over 13C and life sequesters carbon. It therefore removes more 12C than 13C producing a richer 13C environment than the substance originally making up the proto-Earth. Changing that ratio points to carbon sequestered by life or incoming carbon from outer space.

With today's technology, measurements of isotopic ratios isn't hard to do. Accurately dating the past is very hard to do. The title of this thread is misleading, but still correct in a way. The carbon isotope excursion could be the result of adding CH4 or any carbon sequestered by life, which is 13C-depleted. All fossil fuels have different carbon isotope ratios than the normal carbon we live with on the surface of the Earth. It could be the addition of extra-terrestrial carbon or done in a way to add more biologically sequestered carbon. That's why methane hydrates and bolide impact are suspected.

I can totally understand the need to spend grant money getting the most scientific evidence it will produce. The potentials for advancements in chronology are not dependent on the couplets being annual, any periodicity serves the same purpose for an event that happened around 55.8 million years ago. With my limited knowledge of clays and sedimentary rocks, I think the couplets are annual and capture nearly the moment of the CIE, as far as a shallow water column can show.

The evidence I see in the clays is consistent with weathering from the Delaware and Susquehanna rivers of today. I believe such weathered materials separate on the ocean floor and produce those layered sedimentary rocks we see so often and some do reflect seasonal changes. The chemistry between kaolinitic clay and (smectite clays and micaceous silts) should allow the ocean to separate them in distinct annual layers under the right conditions of deposit. If such deposits aren't weathered away, they can reveal details of Earth's past history.

Personally, I believe it's a mistake to go too far trying to tie the past to our present global warming problems. If someone doesn't believe adding or subtracting CO2 will change the environment, then they don't know the history of the Earth, because it certainly does. I also think the doomsday message is a mistake. Harping on a message of fear just shows a lack of understanding of human nature. People don't respond to fear unless it's attacking them at the moment. Our children were born that way and even as adults we will behave that way. It's in our very nature. There is nothing wrong with using a little creativity and putting a spoon full of sugar to make the medicine go down in our message. You have to provide people with hope.

The last paragraph wasn't anything personal to you. I have a hard time reading your blog, because it is white on black background and I don't know what your position is on that issue, based on what I've read elsewhere. I can understand how someone thinks they are doing a service by saying such things, but I know it's a mistake. If it doesn't work, so try another approach! My interests aren't in my vanity of being right, but making sure the future is brighter for humanity.
Title: Re: Possibly important paper regarding CH4
Post by: ggelsrinc on October 18, 2013, 03:42:37 AM
My guess as to the possible origin of such a large release would be the disturbance of a massive natural gas field by tectonic movement. Either India or Australia colliding with Asia would suffice.

The problem with that hypothesis is India was only getting close to Asia and Australia was still near our present Antarctica. Another problem is we have never discovered a natural gas field nearly of the size needed to supply the amount of carbon needed to produce the CIE PETM event and to do so as rapidly as indicated by many studies. Our ability to date the past is very limited, because much of it depends on particular fossils existing widespread throughout the Earth and dying off at a particular moment. They are called index fossils. They can give us a black on white picture of approximately what happened in the past, but can't provide a full color version. 

Scotese is a good site for Paleogeography, but here is another useful site with both links:

http://www.scotese.com/ (http://www.scotese.com/)

http://www.palaeogeography.net/palaeogeography/cenozoic_maps/pg_eocene1/pjmg1eoc1.html (http://www.palaeogeography.net/palaeogeography/cenozoic_maps/pg_eocene1/pjmg1eoc1.html)

When talking about the past, you have to look at the world as it once was.
Title: Re: Possibly important paper regarding CH4
Post by: ChrisReynolds on October 20, 2013, 08:38:41 AM
Ggelsrinc,

Sorry for not getting back, I've been busy. I've had a few complaints about the white on black format at my blog, following your complaint I've decided to change it to a black on white template.

I agree that dating is problematic with regards the PETM, but I suspect you'll agree that this paper doesn't attempt to date as it's key message, it just assigns a timescale based on an argument about the timescale of the banding of the clay cores. Whether or not the timing of that banding is correct determines how fast the event happened. I do think the timescale is based on sound argument, but I'm still having massive problems accepting a minimum 1200Gt addition of 13C depleted carbon in such a small period of time.

I agree that this means little for current GW, losing an analogue doesn't change observations such as Semiletov/Shakhova. In any case with the PETM 13C excursion being driven by marine clathrates the analogue would still be flawed due to the Azolla event.

This paper still leaves me very puzzled.
Title: Re: Possibly important paper regarding CH4
Post by: ggelsrinc on October 20, 2013, 08:21:25 PM
Ggelsrinc,

Sorry for not getting back, I've been busy. I've had a few complaints about the white on black format at my blog, following your complaint I've decided to change it to a black on white template.

I agree that dating is problematic with regards the PETM, but I suspect you'll agree that this paper doesn't attempt to date as it's key message, it just assigns a timescale based on an argument about the timescale of the banding of the clay cores. Whether or not the timing of that banding is correct determines how fast the event happened. I do think the timescale is based on sound argument, but I'm still having massive problems accepting a minimum 1200Gt addition of 13C depleted carbon in such a small period of time.

I agree that this means little for current GW, losing an analogue doesn't change observations such as Semiletov/Shakhova. In any case with the PETM 13C excursion being driven by marine clathrates the analogue would still be flawed due to the Azolla event.

This paper still leaves me very puzzled.

I have no dispute that quickly adding CO2 to our atmosphere is a very dangerous thing to do and understand why people look and find examples from the past to try to prove their global warming case, such as PETM.

I hope the annual hypothesis is correct, whether it involves the moment of PETM or any event that occurred, because accurately finding any event of the past around 55.8 million years ago offers the potential to calibrate other dating methods, which aren't very good.

Their consideration that the CIE event during PETM was nearly spontaneous is reasonable, based on all the studies I have read. Their proof is lacking, because it needs solid evidence beyond a footnote linking their clay samples to that exact period of the past. Finding an index microfossil in the specific samples they took that dates to the PETM period is much more convincing than claiming the carbon isotope change they found has to come from the PETM period, because so and so dated the Marlboro Clay to that period, which is the reason they looked. Their samples should contain something like a foraminifera that became extinct during PETM and other contemporary microfossils of that period.

Everything about PETM is a puzzle to me. The amount of methane clathrates in the oceans are believed to be less then than exist today. The only volcanic event during that time I've ever heard about is that kimberlite field in Canada. That material is believed to originate deep within the Earth and is carbon rich. Could the Earth burp up that much carbon, as some scientists believe? Evidence of shocked quartz points to a bolide event, but linking that evidence to a particular event isn't an easy task.

If the paper's findings hold up, I would be thinking the area isn't that unique and try to find similar areas dating back to that time containing similar records. I'm sure it wasn't the only area on Earth with a river flowing to the ocean and leaving evidence of it's sediments.       
Title: Re: Possibly important paper regarding CH4
Post by: Steven on September 23, 2014, 07:27:07 PM
From Skeptical Science:

http://www.skepticalscience.com/the-perplexing-PETM.html (http://www.skepticalscience.com/the-perplexing-PETM.html)


" One paper last fall suggested that the onset of the PETM occurred in as little as 13 years, based on seemingly annually-layered clays in New Jersey. Those authors concluded the PETM was likely caused by a comet exploding in the atmosphere, and was too fast to be a useful analog for modern global warming. "

" But that paper’s conclusions were demolished in a series of responses, which pointed out that the heat capacity of the oceans required centuries to warm to the PETM extent, that an instant release of carbon in the atmosphere would produce a carbon isotopic shift far larger than observed, and that microfossils ruled out the sedimentary rates claimed. "

" Currently the PETM emissions are estimated to have been spread over between 1,000 and 6,000 years, based on their effects on ocean chemistry and the carbon isotope excursion."
Title: Re: Possibly important paper regarding CH4
Post by: ccgwebmaster on December 21, 2014, 03:09:44 PM
This paper still leaves me very puzzled.

I think it was worth linking to this in the context of this thread. It appears to suggest there were two seperate isotopic shifts, which would tend to undermine the cometary idea further.

http://arstechnica.com/science/2014/12/record-of-past-warming-event-shows-carbon-was-emitted-fast-and-twice/ (http://arstechnica.com/science/2014/12/record-of-past-warming-event-shows-carbon-was-emitted-fast-and-twice/)

I haven't looked into this much, just stumbled over it and thought it worth adding into this discussion. I think I'm leaning towards the timescale must be wrong with the original paper that prompted all this - but either way - I think clathrates win the day when it comes down to the potential for multiple events.