2011-04-19 09:56:22Wakening the Kraken; Fork inserted
Agnostic

mikepope_9@hotmail...
118.208.183.137

See below for updated version

2011-04-19 15:06:21
Ari Jokimäki

arijmaki@yahoo...
91.154.102.190

This just published paper suggests that methane release would enhance ocean acidification but on the other hand: "the impact of methane release on global warming, however, would not be significant within the considered time span." (Time span being next 100 years.)

2011-04-19 15:22:01Put it into blog format for you (working title has the link)
Daniel Bailey
Daniel Bailey
yooper49855@hotmail...
97.83.150.37
See updated version below.
2011-04-19 21:19:40
Hoskibui

hoskibui@gmail...
194.144.161.27

This is very interesting.

About this sentance - is it something that we know?

We also know that the PETM was initiated by changes of the orbital parameters of the Earth (eccentricity, obliquity and precession of axis) causing an increase in the intensity and distribution of solar radiation reaching the earth.

It is quite possible that I have missed something.

2011-04-19 22:48:15
Hoskibui

hoskibui@gmail...
194.144.161.27

I have another question about this:

We know from air trapped in ice cores, the composition of marine exoskeletons and other proxies, that in the past there have been sudden changes in global warming caused by releases of greenhouse gases

This is a bit confusing, sudden changes in global warming caused by releases of greenhouse gases, is it possible to spot that in ice cores? The time frame of the post is a bit confusing - it swithces to much between different timescales, i.e. PETM and glacier periods.

I see it like this - PETM was either caused by eruptions or impact. Glacier period on the other hand because of changes in orbital parameters.

The post is still very interesting - but confusing. I need some clarifications before my head explodes :)

2011-04-20 08:27:59Important nomenclature error.
Glenn Tamblyn

glenn@thefoodgallery.com...
124.176.165.152

Agnostic. You are calling the PETM the 'Permian-Eemian Thermal Maxima (PETM)' Thats incorrect. The Permian was around 286 to 248 MYr ago while the Eemian was the end of one of the most recent Ice Ages in our current era.

The correct name is the Paleocene-Eocene Thermal Maximum. You also need to be sure that the that the paleo-map you show is for the correct period. Not the Permian. Scotese doesn't have a map of exactly the PETM, probably the closest is this from the middle Eocene.

It would also be good to link as well directly to the Shakhova paper at Science, even if it just the pay-walled abstract, giving original source and not just news reports of it.

2011-04-20 09:12:38
Daniel Bailey
Daniel Bailey
yooper49855@hotmail...
97.83.150.37

Good catch on that name/map boo-boo, Glenn.  I missed it & compounded it by then grabbing the wrong map.  Closest I could find for now is from the Eocence (um, same as you found...would've saved me time if I'd have noticed the linky), circa 50 MYA.

2011-04-20 09:25:17scheduled
dana1981
Dana Nuccitelli
dana1981@yahoo...
64.129.227.4

I've got this one on the schedule for publication tomorrow.  Is that okay - is it ready to go?

2011-04-20 09:36:32
Agnostic

mikepope_9@hotmail...
118.208.29.191

Daniel Bailey

 

I thought this draft might get your attention, particularly since I have included two mistakes that I know of.

 

The map you inserted suggests massive volcanic activity and not changes in earths orbital parameters being responsible for rapid increase in temperature resulting in the PETM.

 

Wouldn’t volcanic activity of that magnitude lasting a million years and pouring our huge amounts of basalt, have produced sufficient aerosols to cool the planet? Would volcanoes have produced methane and if so would it not have burned and oxidised to far less warming CO2?  Would the quantity produced been sufficient to initiate an amplifying carbon feedback resulting in sudden rapid warming?

 

Volcanism could have contributed to melting of clathrates causing rapid release of methane.  I thought the carbon isotopic record tended to confirm the source of a rapid increase in atmospheric carbon as being methane – an increase sufficient to raise temperatures by 6°C (which is where I think we are now heading).  Then again, could methane have achieved that outcome in the presence of volcanic aerosols?

 

Another problem is that I do not know how to get in touch with you except by posting a draft article which is rather a public way of having a discussion.  I shall keep an eye open for your article in due course which I know will be far better informed and reasoned than my draft.  If you have no objection, I shall ask John to delete my draft which has done its job of perking your interest.  I still think the last word of Alfred Lord Tennysons poem should be “kill” for the context.  But that would probably horrify poetry purists.

2011-04-20 09:49:27
Agnostic

mikepope_9@hotmail...
118.208.29.191

Dana

Your joking!  Your surely not referring to publication of a first draft - at least not under my name.  It needs lots of critical comment.

 

Glen

Thanks, I know about the Eocene/Eemian thing.  It was one of two deliberate mistakes.

 

Hoskibui

PETM was caused by eruptions or impact.  On eruptions I have commented.  On impact, I did not know there was evidence of this?

2011-04-20 09:51:29Updated per Glenn's comments above
Daniel Bailey
Daniel Bailey
yooper49855@hotmail...
97.83.150.37

yooper49855@hotmail.com

 

Email anytime.

 

The End-Permian, which my wrong map featured, had the Siberian traps.  My bad.

 

Gotta run; back in an hour or two.

2011-04-20 09:53:08
Daniel Bailey
Daniel Bailey
yooper49855@hotmail...
97.83.150.37

Shakhova's full presentation can be found here (preScience publication version):

http://www.google.com/url?sa=t&source=web&cd=9&ved=0CFUQFjAI&url=http%3A%2F%2Fsymposium.serdp-estcp.org%2Fcontent%2Fdownload%2F8914%2F107496%2Fversion%2F1%2Ffile%2F1A_Shakhova_Final.pdf&rct=j&q=How%20Stable%20Is%20the%20Methane%20Cycle%3F%20shakhova%20et%20al%202010%20Science%20filetype%3Apdf&ei=Wh2uTe-PKYvurAHCwKBh&usg=AFQjCNFtVUZ--zStgra5BP2FYkTvGnmgRg&sig2=5IKFlH_e7fBnb5NPS8ZBqA&cad=rja

2011-04-20 11:05:05Not ready?
dana1981
Dana Nuccitelli
dana1981@yahoo...
69.230.97.203
Oh, I thought this was about ready. I'll take it off the schedule.
2011-04-20 11:15:11
Andy S

skucea@telus...
66.183.165.122

I've just glanced through this and there are a lot of errors and it's definitely not ready to go. It will take me quite a while to go through it in detail (and I have to finish my tax return and cook dinner first).

2011-04-20 11:15:29
Daniel Bailey
Daniel Bailey
yooper49855@hotmail...
97.83.150.37

Thanks, Dana; it really needs another 3-4 sets of eyes yet.

Including my own (2 job interviews tomorrow, so I haven't given't it much more than a cursory read yet, as evidenced by my missing the things Glenn found straightaway).


Hoskibui, I don't think Agnostic's draft was intended to specifically come down in favor of a specific causative "smoking gun" as the "trigger man" for the PETM.  On the contray, the point is that, based on what we already know, the PETM discussed in the draft looms as the most likely comp in the paleo record for the world of the 21st Century and beyond.

Between Carozza et al (2011) and Shakhova et al (2010), we have two strident, red-painted klaxxons (warning sirens) blaring away at full volume; sirens which we ignore to our peril.

So either we sober up and start taking action or we risk "Wakening the Kraken".

2011-04-20 14:53:35
Andy S

skucea@telus...
66.183.165.122

My comments in blue

 

Methane is an extremely potent greenhouse gas, 20-30 times more powerful than CO2, over a hundred-year period  

Fortunately it normally occurs in very low concentration in the atmosphere – about 0.3 to 0.4ppm during glacial periods and 0.6 to 0.7ppm during warmer periods.

In 1750 the concentration was ~0.7ppm.  By 2010 it had reached >1.8ppm, and is now at its highest level in 500,000 years. This is a better Wiki reference since it has graphs which show the actual concentrations of CH4 in the ice ages and recent times.

Methane produced on the sea bed in very cold conditions, or in deep water where there is high pressure, combines with water molecules to form an ice-like substance called a clathrate The methane is produced (biogenically) in the sediments below the sea bed and most of the hydrate is stored within shallow sediments and not usually on the the seabed.

We know from air trapped in ice cores, the composition of marine exoskeletons and other proxies, that in the past there have been sudden changes in global warming caused by releases of greenhouse gases.  These rapid, massive releases were characterised by unusual deficiency in carbon isotope 13 (∂13C ) and massive extinction of animals, most recently at the time of the Paleocene-Eocene Thermal Maximum (PETM), about 55.8m years ago. As far as I know, none of the ice-age cycles have been attributed to methane releases, so I would remove the reference to ice cores. The PETM (and maybe some other events in the Tertiary) was certainly related to a light isotope event but I'm not sure about older events. I'd have to check.

We also know that the PETM was initiated by changes of the orbital parameters of the Earth (eccentricity, obliquity and precession of axis) causing an increase in the intensity and distribution of solar radiation reaching the earth.  This in turn, over many thousands of years, triggered natural climate change, amplified by methane releases characterised by a ∂13C deficiency. No, we don't know the trigger of the PETM and the researchers (including Archer) at last years AGU were even casting some doubt on the role of hydrates because the amount of CH4 needed for the isotope effect would be insufficient for the temperature increase and (I think)the ocean acidification observed then.

The only difference between the PETM (Natural) and present (Anthropogenic) global warming is that the former was initiated by increased exposure to solar radiation causing carbon feedbacks and rapid global warming.  The latter is caused by on-going burning of fossil fuels, increasing CO2in the atmosphere, initiating carbon feedbacks. There are some very big differences between the PETM world and now but the similarity is that both events are caused by geologically sudden increases (of the order of doubling IIRC) in atmsopheric carbon.

Natural global warming rectifies by return to orbital parameters which reduce exposure to solar radiation.  This explains why post maximum temperatures are slow to fall.  The mechanism for reducing anthropogenic global warming, initiated through radiative forcing of greenhouse gases is to stop emissions and reduce their concentration in the atmosphere to levels which do not stimulate carbon feedbacks. I don't understand this paragraph.

Carozza et al (2011) find that Natural Global Warming occurred in 3 stages:  First, changing orbital parameters initiated the end of the glacial epoch; second, a rapid increase in greenhouse gases (possibly taking less than 100 years) then amplified the weak orbital signal; third, in the second half of the transition, warming was further amplified by decreasing albedo caused by melting of snow and the large ice sheets in the Northern Hemisphere. That paper has no mention of glacial epochs or orbital forcing changes.

-----

 

That's all I have time for for now.

As a quick additional commentI think that the rest of the article is a lttle too definite, even alarmist. I suggest that you read David Archer's RealClimate commentaries here and here on methane and perhaps tone it down a little.

Archer:

Anyway, so far it [the gas in the Shakhova paper] 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.

2011-04-21 12:51:51
Daniel Bailey
Daniel Bailey
yooper49855@hotmail...
97.83.150.37

Thanks for the input, Andy.  I'll take a gander at it in the morning & update it for further consideration.

2011-04-21 16:27:48
Rob Painting
Rob
paintingskeri@vodafone.co...
118.92.111.75

It is just me?, but I have to scroll across the page just to read this thing.

2011-04-21 16:46:31
Agnostic

mikepope_9@hotmail...
118.208.29.191

Nope, its not just you.  I copied it all on to a word sheet, so avoided the need to scroll.

2011-04-22 02:16:05
logicman

logicman_alf@yahoo.co...
86.148.172.104

Daniel: here's a cleaned up ( de-Googlegarbaged ) url for the Shakhova paper:

http://symposium.serdp-estcp.org/content/download/8914/107496/version/1/file/1A_Shakhova_Final.pdf

 

Andy:

"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."

 

My deepest concern is that various commercial interests see the melt out of the Arctic as an opportunity to access the methane for commercial gain.  We should be emphasising as strongly as possible that the denier argument "we don't know enough" is not applicable to global warming but is irrefutably applicable to the commercial exploitation of clathrates.

 

The Gulf oil disaster proceeded as long as it did precisely because the engineers did not know how to deal with substantial methane release in cold water at depth.  A disaster in the Arctic on the scale of the Gulf disaster, but involving methane extraction could conceivably involve an uncontrollable catastrophic release of methane.  Much of the oil released in the Gulf was pumped into ships.  That cannot be done with methane: an uncontrolled release of methane at the same scale as the Gulf wild well would, if ignited, make a fuel-air bomb look like a fire-cracker.

 

An oil well fire can be extinguished - with difficulty.  In my opinion, a methane fire would be so spread out that it would be imposible by any conceivable means to extinguish it.  The fire would continue to burn until all the methane was exhausted.  The effect on the global climate of such a massive atmospheric input of resulting CO2 would be horrendous.

2011-04-22 03:00:45
Daniel Bailey
Daniel Bailey
yooper49855@hotmail...
97.83.150.37
See update at bottom
2011-04-22 03:03:35
Daniel Bailey
Daniel Bailey
yooper49855@hotmail...
97.83.150.37

Above updated before logicman's comment.

2011-04-22 03:13:44comments
dana1981
Dana Nuccitelli
dana1981@yahoo...
64.129.227.4

"Natural sources of methane are include decaying organic material and volcanic activity. Large amounts are produced in anaerobic conditions by bacterial activity on the seabed as well as being slowly emitted by the earths crust.  Methane is thus biogenically produced..."

"By comparison, human greenhouse gas emissions since 1750 amount to some 350 billion tons." <= GHG emissions or methane emissions?  Sounds like GHG, but you might want to say something about this since you're comparing methane to all GHGs.  Maybe say "all human GHG emissions, including CO2", if that's the case.

"This would result in the further prediction by Hansen of a possible sea level rise of ~5 meters before by 2100 according to Hansen et al."

2011-04-22 03:28:34Gotcha
Daniel Bailey
Daniel Bailey
yooper49855@hotmail...
97.83.150.37

Updated per dana.

Tweaked closing paragraph per logicman.

 

Anything further?

2011-04-22 04:13:27
logicman

logicman_alf@yahoo.co...
86.148.172.104

"Evidence supports the massive release of methane over a relatively short period as having caused sudden climate change with fatal consequences, resulting in previous thermal maxima."

 

Suggestion:

Evidence supports the theory that sudden and massive releases of methane caused decade-scale climate changes - with consequent species extinctions - culminating in the Holocene Thermal Optimum.

2011-04-22 09:11:40
Daniel Bailey
Daniel Bailey
yooper49855@hotmail...
97.83.150.37

Good suggestion, Patrick; implemented.

Anybody else?

2011-04-22 13:11:04
logicman

logicman_alf@yahoo.co...
86.148.172.104

I like this version.  It is alarmist, but what the heck - I'm with Hansen on the problems with scientific reticence.

 

Be_afraid!_Be_very_afraid!_Subject_to the following_provisos

 

Scientific reticence and sea level rise, J E Hansen:

http://iopscience.iop.org/1748-9326/2/2/024002/fulltext

2011-04-22 13:37:28
Daniel Bailey
Daniel Bailey
yooper49855@hotmail...
97.83.150.37

When the building is on fire, is it wrong to point to the smoke and yell "fire"?

2011-04-23 02:36:29
dana1981
Dana Nuccitelli
dana1981@yahoo...
64.129.227.4

Post here whenever you're ready to publish this one.  Actually I don't think there's anything else scheduled in the immediate future, so if it's ready you can probably just go ahead and post.

2011-04-23 02:59:21
Daniel Bailey
Daniel Bailey
yooper49855@hotmail...
97.83.150.37

AFAIK, just waiting to see if Andy has time to give it one more eyeball once-over (I emailed him on it).

2011-04-23 07:41:14
Andy S

skucea@telus...
66.183.165.122

Logicman wrote:

My deepest concern is that various commercial interests see the melt out of the Arctic as an opportunity to access the methane for commercial gain.  We should be emphasising as strongly as possible that the denier argument "we don't know enough" is not applicable to global warming but is irrefutably applicable to the commercial exploitation of clathrates.

There's already a whole bunch of conventional discovered gas onshore in the Mackenzie Delta in the Canadian Arctic. This will be much easier to develop, Climate Change or not, than gas hydrates. Arctic gas probably won't be developed for decades and likely never, not because of climate change but because shale gas will likely keep prices so low that a pipeline south will not be economic. There's an onshore clathrate deposit called Mallik that is the subject of a big international research project. See here. There's currently no way to commercially exploit hydrates and they likely won't be touched until shale gas and conventional gas resources have been depleted and the gas price goes up. But I've been wrong before.

To be clear: I was only advising Agnostic not to be alarmist about clathrates contributing to climate change over the next century or so. On a longer timescale, they may well contribute significantly to warming and ocean acidification. And there's plenty, more immediate methane feedbacks in the Arctic to be concerned about, due to melting of the permafrost and oxidation of peat. I think that what Shakhova was seeing was the release of biogenic gas as the impermeable subsea permafrost layer melted and trapped gas underneath it was released, but that's a guess. To be honest, I didn't think much of that paper.

I have recently done some volunteer research work with the Geological Survey of Canada on gas seeps in the Mackenzie Delta. This is at a very early stage and there's nothing much to report but I may be able to persuade one of  the geologists there to do a SkSc post on this sometime soon.

I'll have another look at the Kraken article soon.

2011-04-23 09:46:41Round two!
Andy S

skucea@telus...
66.183.165.122

Corrections in green, comments in [brackets]

 

Methane (CH4) is an extremely potent greenhouse gas, 20-30 times more powerful than carbon dioxide (CO2) on a century timescale.  Fortunately it normally occurs in very low concentration in the atmosphere – about 0.3 to 0.4ppm during glacial periods and 0.6 to 0.7ppm during warmer periods.

In 1750 the concentration was ~0.7ppm.  By 2010 it had reached >1.8ppm, and is now at its highest level in 500,000 years.  This is largely due to human activity, particularly the keeping of large herds of cattle and flocks of chickens and the production of fossil fuels.  Methane has a relatively short life in the atmosphere where it oxidizes into CO2 over a period of 9-15 years.

Natural sources of methane include decaying organic material and volcanic activity.   Large amounts of methane are produced in anaerobic conditions by bacterial activity on in the sediments below the seabed as well as being slowly emitted by the earths crust  by chemical transformation of organic matter at greater burial depths. Methane hydrates are formed by bonding with water to make an ice-like substance in certain temeparture/pressure conditions that can be found at shallow water depths in polar regions and in water depths of several hundred metres or more in lower latitudes. is thus biogenically produced in the shallow sediments of the sea bed under very cold conditions, or in deep water where there is high pressure, and combines with water molecules to form an ice-like substance called a clathrate.[note: methane is formed everywhere, it's the hydrates that form in special conditions]  It yields 164 m3 of CH4 per m3 of solid clathrate.

Like Savoir Faire, Clathrates are seemingly everywhere

Clathrate occurs in the Antarctic and particularly in the Arctic where it is abundant in the relatively shallow though very cold seabed of the vast continental shelves which almost encircle the Arctic Ocean.  It also occurs in the sea bed of warmer waters where they are of sufficient depth to enable it to remain stable. [oops, that's repeated in my edit above]

Methane clathrate has accumulated in  below the seabed over millions of years.  Billions of tons of it lie in the seabed, dormant beneath permafrost, in the pores of sandstones or shrouded in silt.  As long as it remains under pressure or in cold conditions (below 0°C) it is stable and does not release methane.

We know from air trapped in ice cores, the composition of marine exoskeletons and other proxies, that in the past there have been sudden changes in global warming associated with releases of greenhouse gases.  These rapid, massive releases were characterised by unusual deficiency in carbon isotope 13 (∂13C ) and massive extinction of animals, most recently at the time of the Paleocene-Eocene Thermal Maximum (PETM), about 55.8 million years ago. [The ice cores are not relevant to the PETM. Besides the ice cores show increases in CO2 that do not have the light isotopes, indicating that that CO2 came from inorganic sources in the ocean, not from organic carbon]

PETM

The world at the approximate time of the PETM (courtesy Christopher Scotese)

It is believed that the PETM was initiated by changes of the orbital parameters of the Earth (eccentricity, obliquity and precession of axis) causing an increase in the intensity and distribution of solar radiation reaching the earth.  This in turn, over many thousands of years, triggered natural climate change, amplified by CH4 releases characterised by a ∂13C deficiency.

A major difference between the PETM (Natural) and present (Anthropogenic) global warming is that the former was initiated by increased exposure to solar radiation causing carbon feedbacks and rapid global warming.  The latter, geologically sudden increase is primarily caused by the on-going burning of fossil fuels, which yearly inject a massive bolus of COin the atmosphere, initiating further carbon feedbacks. [The ice age climate change events were certainly triggered by orbital varaitions but the orbital trigger for the PETM is, at best, only one hypothesis among many]

Natural global warming is self-rectifying by gradual return of Earth’s orbital parameters to what they were before the onset of global warming, thereby significantly reducing the amount of solar radiation reaching the Earth’s surface.  The result is cooling oceans able to gradually absorb and lower atmospheric CO2, enabling restoration of albedo at higher latitude/altitude, producing further slow global cooling. This explains why post-maximum temperatures are slow to fall.  [Again you are mixing up the ice ages with the older climate changes, like the PETM. For the older climate change events the weathering thermostat (absorption of CO2 by chemical processes related to decomposition of certain minerals) was more important.] The mechanism for reducing anthropogenic global warming, initiated through radiative forcing of greenhouse gases, is to stop emissions and reduce their concentration in the atmosphere to levels which do not stimulate carbon feedbacks. 

I know what you're thinking: Was it one shot or two?

Carozza et al (2011) find that natural global warming occurred in 2 stages:  First, global warming of 3° to 9° C accompanied by a large bolus of organic carbon released to the atmosphere through the burning of terrestrial biomass (Kurtz et al, 2003) over approximately a 50-year period; second,  a catastrophic release of methane hydrate from sediment, followed by the oxidation of a part of this methane gas in the water column and the escape of the remaining CH4 to the atmosphere over a 50-year period.

The description of Stage 2:  Very rapid and massive release of carbon deficient in ∂13C, does put one in mind of the Methane Gun hypothesis.  It postulates that methane clathrate at shallow depth begins melting and through the feed-back process accelerate atmospheric and oceanic warming, melting even larger and deeper clathrate deposits.  The result:  A relatively sudden massive venting of methane - the firing of the Methane Gun.  Recent discovery by Davy et al (2010) of kilometer-wide (ten 8-11 kilometer and about 1,000 1-kilometer-wide features) eruption craters on the Chatham Rise seafloor off New Zealand adds further ammunition to the Methane Gun hypothesis.

It has been known for many years that methane is being emitted from Siberian swamplands hitherto covered by permafrost, trapping an estimated 1,000 billion tons of methane.  Permafrost on land is now seasonally melting and with each season melting it at greater depth, ensuring that each year methane venting from this source increases.

Methane clathrate has accumulated over the East Siberian continental shelf where it is covered by sediment and seawater up to 50 meters deep.  An estimated 1,400 billion tons of methane is stored in these deposits.  By comparison, total human greenhouse gas emissions (including CO2) since 1750 amount to some 350 billion tons.

Significant methane release can occur when on-shore permafrost is thawed by a warmer atmosphere and clathrate at relatively shallow depths is melted by warming water.  This is now occurring.  In both cases, methane gas bubbles to the surface with little or no oxidation, entering the atmosphere as CH4 – a powerful greenhouse gas which increases local, then Arctic atmospheric and ocean temperature, resulting in progressively deeper and larger deposits of clathrate melting. [Onshore clathrates are unlikely to melt over a century timescale because they are located under a few hundred metres of rock and the low thermal conductivity of rock means that they will not warm up for ages]

Methane released from deeper deposits such as those found off Svalbard has to pass through a much higher water column (>300 meters) before reaching the surface.  As it does so, it oxidises to CO2, dissolving in seawater or reaching the atmosphere as CO2which causes far slower warming but can nevertheless contribute to ocean acidification.

A significant release of methane due to melting of the vast deposits trapped by permafrost and clathrate in the Arctic would result in massive loss of oxygen, particularly in the Arctic ocean but also in the atmosphere.  Resulting hypoxic conditions would cause large extinctions, especially of water breathing animals, which is what we find at the PETM.

Shakhova et al (2010) reports that clathrate on the continental shelf of East Central Siberia (ECS), with an area of over 2 million km2, is melting and emitting more methane than all other ocean sources combined.  She calculates that methane venting from the ECS is now in the order of 8 million tons per annum and increasing.  This equates to ~200 million tons/annum of CO2, more than the combined CO2 emissions of Scandinavia and the Benelux countries in 2007. [I doubt that the methane there is from clathrates because any clathrates in those shallow water depths would be covered by a hundred metres or more of insulating sediment and they would not have yet felt the effect of gloabal warming. It is more likely that the methane is from non-hydrate methan that was previously kept in place by thin and now melting permafrost at the sea bed.]

Release of ECS methane is already contributing to Arctic amplification resulting in temperature increase exceeding twice the global average.  The rate of release from the tundra alone is predicted to reach 1.5 billion tons of carbon per annum before 2030, contributing to accelerated climate change, perhaps resulting in sustained decadal doubling of ice loss causing collapse of the Greenland Ice Sheet (Hansen et al, 2011).  This would result in a possible sea level rise of ~5 meters before 2100, according to Hansen et al.

Evidence supports the theory that sudden and massive releases of methane caused decade-scale climate changes - with consequent species extinctions - culminating in the Holocene Thermal Optimum. [That Wiki reference has no mention of methane or hydrates. I'm not sure this is correct and I'd like to see a refrence for it.]

'Ware the Kraken

In summary, immense quantities of methane clathrate have been identified in the Arctic.  Were a fraction of these to melt, the result would be massive release of carbon, initially as CH4 causing deeper clathrate to melt and oxidise, adding CO2 to the atmosphere.  Were this to occur, it would produce sudden greatly worsen global warming.

While natural global warming during the ice ages was probably initiated by increased solar radiation caused by cyclic self-correcting changes to Earth’s orbital parameters, there is no evident mechanism for correcting Anthropogenic Global Warming over the next several centuries.  The latter has already begun producing methane and CO2 in the Arctic melting Arctic clathrate, starting a feedback process which may lead to uncontrollable, very dangerous global warming, akin to that which occurred at the PETM. 

This extremis we ignore - to our peril.

2011-04-23 12:41:55Unless there are any other takers, ready to go live (changes made per Andy's valued comments)
Daniel Bailey
Daniel Bailey
yooper49855@hotmail...
97.83.150.37

Wakening the Kraken

Posted on 23 April 2011 by Agnostic & Daniel Bailey

Methane (CH4) is an extremely potent greenhouse gas, 20-30 times more powerful than carbon dioxide (CO2) on a century timescale.  Fortunately it normally occurs in very low concentration in the atmosphere – about 0.3 to 0.4ppm during glacial periods and 0.6 to 0.7ppm during warmer periods.

In 1750 the concentration was ~0.7ppm.  By 2010 it had reached >1.8ppm, and is now at its highest level in 500,000 years.  This is largely due to human activity, particularly the keeping of large herds of cattle and flocks of chickens and the production of fossil fuels.  Methane has a relatively short life in the atmosphere where it oxidizes into CO2 over a period of 9-15 years.

Large amounts of methane are produced in anaerobic conditions by bacterial activity in the sediments below the seabed as well as by chemical transformation of organic matter at greater burial depths. Methane hydrates are formed by bonding with water to make an ice-like substance in certain temeparture/pressure conditions that can be found at shallow water depths in polar regionsIt yields 164 m3 of CH4 per m3 of solid clathrate.

Like Savoir Faire, Clathrates are seemingly everywhere

Clathrate occurs in the Antarctic and particularly in the Arctic where it is abundant in the relatively shallow though very cold seabed of the vast continental shelves which almost encircle the Arctic Ocean.  It also occurs in the sea bed of warmer waters where they are of sufficient depth to enable it to remain stable.

Methane clathrate has accumulated below the seabed over millions of years.  Billions of tons of it lie dormant beneath permafrost, in the pores of sandstones or shrouded in silt.  As long as it remains under pressure or in cold conditions (below 0°C) it is stable and does not release methane.

We know that in the past there have been sudden changes in global warming associated with releases of greenhouse gases.  These rapid, massive releases were characterised by unusual deficiency in carbon isotope 13 (∂13C ) and massive extinction of animals, most recently at the time of the Paleocene-Eocene Thermal Maximum (PETM), about 55.8 million years ago.

PETM

The world at the approximate time of the PETM (courtesy Christopher Scotese)

It is believed that the PETM was likely initiated by changes of the orbital parameters of the Earth (eccentricity, obliquity and precession of axis) causing an increase in the intensity and distribution of solar radiation reaching the earth (Sexton et al, 2011).  This in turn, over many thousands of years, triggered natural climate change, amplified by CH4 releases characterised by a ∂13C deficiency.

A major difference between the PETM (Natural) and present (Anthropogenic) global warming is that the former was likely initiated by increased exposure to solar radiation causing carbon feedbacks and rapid global warming.  The latter, geologically sudden increase is primarily caused by the on-going burning of fossil fuels, which yearly inject a massive bolus of CO2 in the atmosphere, initiating further carbon feedbacks.

Natural global warming is self-rectifying either by slow chemical weathering processes responsible for mineral sequestration of carbon or by gradual return of Earth’s orbital parameters to what they were before the onset of global warming, thereby significantly reducing the amount of solar radiation reaching the Earth’s surface.  The result is cooling oceans able to gradually absorb and lower atmospheric CO2, enabling restoration of albedo at higher latitude/altitude, producing further slow global cooling. This explains why post-maximum temperatures are slow to fall.  The mechanism for reducing anthropogenic global warming, initiated through radiative forcing of greenhouse gases, is to stop emissions and reduce their concentration in the atmosphere to levels which do not stimulate carbon feedbacks.

I know what you're thinking: Was it one shot or two?

Carozza et al (2011) find that natural global warming occurred in 2 stages:  First, global warming of 3° to 9° C accompanied by a large bolus of organic carbon released to the atmosphere through the burning of terrestrial biomass (Kurtz et al, 2003) over approximately a 50-year period; second,  a catastrophic release of methane hydrate from sediment, followed by the oxidation of a part of this methane gas in the water column and the escape of the remaining CH4 to the atmosphere over a 50-year period.

The description of Stage 2:  Very rapid and massive release of carbon deficient in ∂13C, does put one in mind of the Methane Gun hypothesis.  It postulates that methane clathrate at shallow depth begins melting and through the feed-back process accelerate atmospheric and oceanic warming, melting even larger and deeper clathrate deposits.  The result:  A relatively sudden massive venting of methane - the firing of the Methane Gun.  Recent discovery by Davy et al (2010) of kilometer-wide (ten 8-11 kilometer and about 1,000 1-kilometer-wide features) eruption craters on the Chatham Rise seafloor off New Zealand adds further ammunition to the Methane Gun hypothesis.

It has been known for many years that methane is being emitted from Siberian swamplands hitherto covered by permafrost, trapping an estimated 1,000 billion tons of methane.  Permafrost on land is now seasonally melting and with each season melting it at greater depth, ensuring that each year methane venting from this source increases.

Methane clathrate has accumulated over the East Siberian continental shelf where it is covered by sediment and seawater up to 50 meters deep.  An estimated 1,400 billion tons of methane is stored in these deposits.  By comparison, total human greenhouse gas emissions (including CO2) since 1750 amount to some 350 billion tons.

Significant methane release can occur when on-shore permafrost is thawed by a warmer atmosphere (unlikely to occur in significance on less than a century timescale) and undersea clathrate at relatively shallow depths is melted by warming water.  This is now occurring.  In both cases, methane gas bubbles to the surface with little or no oxidation, entering the atmosphere as CH4 – a powerful greenhouse gas which increases local, then Arctic atmospheric and ocean temperature, resulting in progressively deeper and larger deposits of clathrate melting.

Methane released from deeper deposits such as those found off Svalbard has to pass through a much higher water column (>300 meters) before reaching the surface.  As it does so, it oxidises to CO2, dissolving in seawater or reaching the atmosphere as CO2 which causes far slower warming, but can nevertheless contribute to ocean acidification.

A significant release of methane due to melting of the vast deposits trapped by permafrost and clathrate in the Arctic would result in massive loss of oxygen, particularly in the Arctic ocean but also in the atmosphere.  Resulting hypoxic conditions would cause large extinctions, especially of water breathing animals, which is what we find at the PETM.

Shakhova et al (2010) reports that the continental shelf of East Central Siberia (ECS), with an area of over 2 million km2, is emitting more methane than all other ocean sources combined.  She calculates that methane venting from the ECS is now in the order of 8 million tons per annum and increasing.  This equates to ~200 million tons/annum of CO2, more than the combined CO2 emissions of Scandinavia and the Benelux countries in 2007.  This methane is likely sourced from non-hydrate methane previously kept in place by thin and now melting permafrost at the sea bed, melting clathrates, or some combination of both.

Release of ECS methane is already contributing to Arctic amplification resulting in temperature increase exceeding twice the global average.  The rate of release from the tundra alone is predicted to reach 1.5 billion tons of carbon per annum before 2030, contributing to accelerated climate change, perhaps resulting in sustained decadal doubling of ice loss causing collapse of the Greenland Ice Sheet (Hansen et al, 2011).  This would result in a possible sea level rise of ~5 meters before 2100, according to Hansen et al.

Evidence supports the theory that sudden and massive releases of greenhouse gases, including methane, caused decade-scale climate changes - with consequent species extinctions - culminating in the Holocene Thermal Optimum.

'Ware the Kraken

In summary, immense quantities of methane clathrate have been identified in the Arctic.  Were a fraction of these to melt, the result would be massive release of carbon, initially as CH4 causing deeper clathrate to melt and oxidise, adding CO2 to the atmosphere.  Were this to occur, it would greatly worsen global warming.


While natural global warming during the ice ages was initiated by increased solar radiation caused by cyclic changes to Earth’s orbital parameters, there is no evident mechanism for correcting Anthropogenic Global Warming over the next several centuries.  The latter has already begun producing methane and CO2 in the Arctic, starting a feedback process which may lead to uncontrollable, very dangerous global warming, akin to that which occurred at the PETM.

This extremis we ignore - to our peril.

2011-04-26 23:47:54
Hoskibui

hoskibui@gmail...
194.144.161.27

I still want to know where this sentance comes from (reference if possible):

It is believed that the PETM was likely initiated by changes of the orbital parameters of the Earth (eccentricity, obliquity and precession of axis) causing an increase in the intensity and distribution of solar radiation reaching the earth. 

It is just my thirst for knowledge, I know it is late :)

2011-04-27 00:04:49
Rob Painting
Rob
paintingskeri@vodafone.co...
118.92.113.85

Hoskibui, have a read of this paper Eocene global warming events driven by ventilation of oceanic dissolved organic carbon - Sexton 2011. Figure 1c shows the "hyperthermals" including the PETM seem to be very regular and in sync with precessional changes. Note the citations too, James Zachos has published a few highly cited papers on the PETM - worth a read. 

2011-04-27 00:17:35
Hoskibui

hoskibui@gmail...
194.144.161.27

Cheers - will look at that.

2011-04-27 00:20:41
Daniel Bailey
Daniel Bailey
yooper49855@hotmail...
97.83.150.37

Thanks, Rob; I added that citation to support that paragraph in the post.