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Author Topic: When will Sea Methane Vapourise?  (Read 6746 times)

Offline Titanscape

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When will Sea Methane Vapourise?
« on: 01/11/2011 22:58:32 »
When will the frozen sea methane vapourize and come to the surface? Could under sea projects accidentally speed this up?

How would this effect surface life and temperature?


 

Offline yor_on

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When will Sea Methane Vapourise?
« Reply #1 on: 02/11/2011 19:50:17 »
Nobody knows, it depends on what depth the methane is, and the temperature of the water, underwater currents, etc. But it is bubbling away already in the shallow waters of the arctic. What is might do is to kill of the marine life where it is concentrated as it consumes the oxygen, after that as the ocean gets saturated it will reach the surface to join our atmosphere. Methane is a more intense 'heat holder' (20 times more over a 100-year period about) that CO2, but also has a much quicker 'turnover' in the atmosphere, some decades only as compared to CO2 that stays for centuries up to millennium (its 'tail'), showing its strongest effect inside a century. We have already seen it come up (2008).

"At some locations he said concentrations of the gas were 100 times the background level. These anomalies were documented in the East Siberian Sea and the Laptev Sea, covering several tens of thousands of square kilometres.

Gustafsson added: "The conventional thought has been that the permafrost 'lid' on the sub-sea sediments on the Siberian shelf should cap and hold the massive reservoirs of shallow methane deposits in place.

"The growing evidence for release of methane in this inaccessible region may suggest that the permafrost lid is starting to get perforated and thus leaking methane."

Estimates for the amount of carbon locked up in the hydrates vary from 500 to 5000 gigatonnes. Scientists predict that warming will release some of these deposits, but modeling the temperature rise that would trigger significant releases has proved extremely difficult."

The Methane cycle in the atmosphere can be divided in three parts.

"
1. Oxidation of methane and formation of formaldehyde;
2. Oxidation (removal) of formaldehyde and formation of carbon monoxide;
3. Oxidation (removal) of carbon monoxide and formation of carbon dioxide.
"

So it ends up as carbon monoxide and carbon dioxide, which will be a bigger problem in the long run. But it's seen more as the icing on the cake, not the cake itself which CO2 is judged to be, due to its much longer life length. It may become what some call a 'tipping point' though, defining the place of no return for us.
 

Offline yor_on

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When will Sea Methane Vapourise?
« Reply #2 on: 02/11/2011 20:47:17 »
You will also find methane in rice field, and all sort of organic debris and wastes. So the Siberian tundra for example is releasing a lot as it warms up. But this is a new phenomena geologically, and even though we have found strong evidence for swift, as in decades, not centuries, geological shifts before and there found no clear evidence of it being a 'methane kick' that made them possible, we can't use that as evidence that it can't happen. There are worrying factors to consider. One is the micro organisms living under the ice sheets in Antarctica.

" Trapped within the ice were high concentrations of methane, Wadham said, as well as methanogens themselves — up to 10 million cells per gram in the Antarctic sample and 100,000 cells per gram in Greenland. That’s comparable to the concentration of methanogens found in deep-ocean sediments, she said. The species of microbes were also similar to those found in other polar environments, such as Arctic peat or tundra. The team then put scrapings from both sites into bottles and incubated them with water to see which microbes might grow. For the Antarctic samples, Wadham said, “nothing happens for 250 days and then bam! You get tons of methane.” " From Methane Under Antarctic Ice

And then you have Thawing permafrost. "    The thaw and release of carbon currently frozen in permafrost will increase atmospheric CO2 concentrations and amplify surface warming to initiate a positive permafrost carbon feedback (PCF) on climate…. [Our] estimate may be low because it does not account for amplified surface warming due to the PCF itself….  We predict that the PCF will change the arctic from a carbon sink to a source after the mid-2020s and is strong enough to cancel 42-88% of the total global land sink. The thaw and decay of permafrost carbon is irreversible and accounting for the PCF will require larger reductions in fossil fuel emissions to reach a target atmospheric CO2 concentration."

Combine those with what already is happening with the phytoplankton and the marine life world wide, due to our global warming and overfishing, and we get a very bleak picture of our kids prospects. So are we humans just plain dumb? I don't think so, but all BS aside we never have been in the place of being the caretakers of this planet before. We've just been the smartest animals around. But now we need to take a step more, we need to be what some idiots already claim us to be, caretakers.
 

Offline yor_on

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When will Sea Methane Vapourise?
« Reply #3 on: 07/11/2011 07:58:03 »
What is worrying is also the way we, as oxygen based life, seem to have a very precarious balance with other types . Some of the mass extinctions we've found is now believed to come from nature losing its ability to produce oxygen, due to anaerobic microbes getting a boost by methane and CO2 (Carbon dioxide) from  volcanoes etc.

Have a look at Peter Ward Mass extinctions. What he is talking about is also those underwater currents regulating and distributing cold and heat "This extinction is ominous given current conditions.  The oceans and land now have life-giving circulation – cold, oxygenated water sinks and flows along the bottom from the poles to the tropics, and warm tropical water flow from the equator north to high latitudes, warming Europe and other regions."

And that, friends, is a question of the melting of the Arctic and Antarctic. With our 'global thinking strategists' expecting it to just become a new and exciting 'geopolitical game' with new gains (profits) in sight. And you trust them more than this, don't you? They promise you 'new jobs', and better 'living standards' :)

Also take a look at this. Mass extinction easier to trigger than thought.

"The cataclysmic extinctions that scoured Earth 200 million years ago might have been easier to trigger than expected, with potentially troubling contemporary implications. Rather than 600,000 years of volcanic activity choking Earth's atmosphere with carbon dioxide, just a few thousand years apparently sufficed to raise ocean temperatures so potent greenhouse gases trapped in seafloor mud came bubbling up."

" "Anthropogenic carbon dioxide emissions dwarf global volcanic carbon dioxide emissions," study researcher Terrance Gerlach, of the U.S. Geological Survey, said in a statement. Carbon dioxide, or CO2, is the main greenhouse gas responsible for climate change. Gerlach crunched the carbon dioxide numbers from earlier studies of volcanic output, finding a range of 0.13 to 0.44 billion metric tons, or gigatons, of CO2 per year. In comparison, the estimated rate of human carbon dioxide emissions for 2010 alone is 35 billion metric tons. "

We are the ones creating this tipping, the worst problem being that we already have passed a tipping point, well, as I suspect anyway.

Mankind is a selfish species, and not really as wise as we think, intelligent yes, fast to make personal gains, but adaptive? Depends on what you mean I think, We're not as 'far' ahead as we think from other animals. And the way we walk over each other to get those 'personal rewards' is to me no different from any other animal trying to survive, with the difference that we learnt how to mass produce. The problem as I think is the way we 'shortcut evolution' to get our 'rewards'. That's what made our man-made global warming possible, not that anyone knew it then, as our industrial revolution started.

Now we have all developing countries mimicking our 'industrial revolution', saying that they too 'deserve' the same 'rewards'. America, a 'spear point' of modern technique, is still being the second, or third, largest producer of CO2 (with 18 tonnes emitted per person) in the world. Soon USA will be overrun though, not by reducing carbon emissions, but by the need of those developing countries to get to to our western 'standard of living', as China already done, and India etc, soon too. World carbon dioxide emissions data by country.

So what is the lesson here, that we can't learn? That's not true, but 'unpleasant learning' is the one we always postpone, it gives us no personal benefit to go down in living standard for example, and so we hope for politicians, or/and 'scientists', to promise us a way out that will keep our benefits, what I call the 'Jules Verne scenario'. Well, that one you can forget, as I see it. There will be a personal decline of 'benefits' for us all.

The question is if we are wise enough to share our resources, and do the best of it, or if we will fall into some 'feeding frenzy' over the limited resources soon to come. We have the knowledge and the technology to start reform our societies into a sustainable living, and actually give us all a better way of living, but we also have the capability as well as 'patriotism' to kill of most of the population on this planet, depending on country, and propaganda.

Personally I don't think we can stop this global warming process, but we may make it endurable if we start to realise that we're on one small, small, planet. And that we only have what we see. We desperately need to become our planet caretakers, not 'conquerors', because that one was a true 'dead end game'. Nature have given us a ultimate challenge, whether we act on it or just let it act upon us? That's what I expect to show us if we really are 'adaptive', or just another oxygen based species, soon to become endangered.
==

Just to get that 'perspective' on where we're heading. We've already gone soo far past the Kyoto treaties intentions, failing miserably in reducing our CO2 emissions. Instead we're gaining 'speed', fouling our planet up, throwing a very big, man made, CO2 wrench in our delicate climate balance.

Why not have a look?
« Last Edit: 07/11/2011 08:47:02 by yor_on »
 

Offline Mazurka

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When will Sea Methane Vapourise?
« Reply #4 on: 07/11/2011 16:16:19 »
I think the question relates to methane clathrates, which form in cold water/ oceanic sediment at depths between 300 -  500m.  In a very simplistic way, most of it is thought to be created by methane (from microbial sources) percolating up through sediments hits the cold water and precipitates out as a clathrate.  As this is a question of phase stabillity, at lower pressures/ higher temperatures, the methane will either disolve or bubble up through the water.

If the oceans warmed at depth the stability of the methane ice will decrease and some will be released into the water column.  If this reaches the surface (as other posters have pointed out) this will contribute to global warming, this may in turn result in increased temperature at depth...

Issues with this is that ocean mixing is poorly understood and the effects of global warming on oceanic circulation may not be as anticipated. Clathrate deposits are generally located on the continental shelf.  There is possibly about twice as much clathrate as there is proven natural gas reserves and it seems likely that commerical exploitation will occurr sooner rather than later.

There are suggestions that the Paleocence Eocence Thermal Maximum (PETM) was linked with a massive release of methane from destabilised clathrates - possibly in relation to the hotspot that is Iceland.
The PETM is the clearest example in the geological record of increased concentration of CO2 ahead of increases in temperature.   

 
 

Offline yor_on

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When will Sea Methane Vapourise?
« Reply #5 on: 07/11/2011 20:51:10 »
If you check you will see I mention that in my first post, also stating that we already (2008) found it 'bubbling up' in the shallow water of the Arctic. That's three years ago, soon to be four Mazurka. So the clathrate gun is already cocked. None of what I write about the methane in the Arctic is news.

And we have a pretty fair notion of what it will mean if it, and the tundra, start to release Methane (and CO2) in greater amounts. But it's new science and we constantly find new triggers and combinations to worry about. If you follow the links I mentioned some, but there are a lot more. As for climate scientists saying that they 'know' what will happen? They're not soothsayers, they're just trying to do do as good as they can, but the evidence for a 'tipping' is growing with every day that goes.
 

Offline Airthumbs

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When will Sea Methane Vapourise?
« Reply #6 on: 08/11/2011 00:55:22 »
Yor_on, here here, very well written and I totally agree on all of your points.  I have a question, if someone can put the current situation into such a concise description then why the hell are we all not having a revolution and over throwing our corrupt governments?

It seems most people just either do not believe we have destroyed the planet or as I suspect, just don't care!

The people who do care really must step up before all is lost, I think it is too late already, we are on a one way ticket to a very, very different world.

When you study conservation today you do not learn how to protect the environment but how to try and save it, mainly it's all about damage reduction and control management.

The true extent of our poisoned planet is yet to be realised but we continue to put toxic chemicals into the environment at a growing rate. 

When all that methane gets released it is going to make our carbon footprint look like a needle in a haystack!
 

Offline CliffordK

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When will Sea Methane Vapourise?
« Reply #7 on: 08/11/2011 05:44:42 »
Most of the ocean is very deep, from one mile deep to several miles deep.

Water's maximum density is at about 4°C, or a little colder for salt water (around 0°C). 

There is a very sharp thermal gradient that keeps the deep water cold at very close to its maximum density around 0°C, in part due to the massive pressure of over a mile deep water column above it.  This force bringing high density water to the bottom of the ocean, and low density water to the surface creates the global ocean currents. 

As I understand it, nearly all of the ocean temperature changes have been near the surface, with very little change recorded at depth. 

The axial tilt of the planet brings total 24 hour darkness during the winter in the area north of the Arctic circle, or in the south, south of the antarctic circle.  And, thus can provide a large supply of very cold water.  Less ice in the winter actually increases the ocean's ability to radiate heat.  Whether that can actually overcome absorbing more energy in the summer is hard to tell.  Certainly this summer's sea ice extent was the second to the least recorded in recent years. 

Anyway, while some shallow methyl-hydrates may be at risk, the deep ones are not at risk at this time.
 

Offline yor_on

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When will Sea Methane Vapourise?
« Reply #8 on: 08/11/2011 19:04:57 »
Read this Deep Ocean Heat Is Melting Antarctic Ice.

And read the comment section.

"When we say “warm” water in polar regions, we are talking relative to the freezing point. So in the above report, warm refers to waters that are 3.5 to 4 degrees warmer than freezing. That is blazing hot for ice (water will melt over 4300 times more ice than air given air and water of the same volume and temperature). But, this hot water is still so cold I wear special scuba gloves when sampling it. Anyway, in most of the oceans where the water temperature is actually warm as you and I would think when touching it, the density of water is controlled by temperature, but in cold regions it is controlled by salinity. So, my “warm” water that is really cold, sinks when it gets saltier (it gets saltier when sea ice forms, since that process only freezes the pure water trapping the ocean salts in a dense salty brine that drains into the ocean raising its salinity and increasing its density so that it sinks). Hope this clarifies this reasonable question for you…"


In a way it is a question of chaos. Namely what a 'tipping' is about. Think of our Earth as a 'heat machine', no, not global warming now, even if it is that I'm talking about too. It has to do with all kinds of stuff, from your wallet and work, to what the temperature might become.

In Chaos theory, which is a description about how small initial differences to, otherwise very similar, 'systems' leads to big, and unpredictable, differences  you find a lot of information of what we can expect.

So think of Earth as a 'heat machine'. The more heat you put into it, the more chaotic you can expect the system to become, and the more unpredictable, with bigger 'swings'. The 'heat' is our needs, and our expectations of the economy to keep growing, 2-3 % at least every year, add infinitum. It's not even logical that idea, but it is the way we seem to look at it. And the faster a country 'grow', the better they expect it to become for their citizens.

So we put in a lot of 'heat' trying to make this happen, and we trust that 'the market' will be able to find its own 'balance'. But in Chaos theory this will have the direct opposite effect, the more complicated the system and the more we 'grow', the more probable that we will meet a tipping that will throw us back. Although a 'tipping' is when a system, like a ball falling down from some precarious high point, finds its new 'semi stable' balance, it may well be foregone by 'swings' up and down before it does so. And as we infuse the climate system with CO2 we also make that 'tipping' more and more certain.

So, can we stop it? Well, we can 'slow down'. And that means slow down economically too. And we can share, our resources and 'green technology'. We can do this, and it will work. It might not stop a Global warming, but it may make it endurable.

As I see it there are two ways to go, one is 'economic wars', nation against nation, competing over dwindling resources. The other is one where we all 'slow down' a little, share and build for a slower economy, but also for a more stable. That includes getting rid of our CO2, finding new and cleaner ways to industrialise, and create that future we all want for our kids.
 

Offline CliffordK

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When will Sea Methane Vapourise?
« Reply #9 on: 08/11/2011 20:40:44 »
There are several different ice structures in Antarctica.
  • Seasonal Sea ice.
    At least, over the last few decades the sea ice extent has been generally stable in Antarctica.  This seems to be the most vulnerable to ocean currents.  See diagram from the article.
  • Multi-Year Sea Ice.
    Again, relatively stable over the last few years in Antarctica, at least in terms of extent.
  • Ice Shelves
    There is some concern about these.  They are generally glacial ice that has extended out into the ocean so that they are floating.  Loss of lower layers of ice will cause an imbalance, and could lead to them collapsing.  A couple of ice shelves along the Antarctic Peninsula have collapsed in recent decades.  However, more research needs to be done to understand the long-term dynamics of the ice shelves.
  • West Antarctic Ice Sheet.
    This is considered vulnerable because, while it is sitting on the ground, the ground level is actually below sea level.  So, there is risk of erosion from the sea.  Note, that some of Greenland is also below sea level, but Greenland is somewhat U-shaped opening northward, with a very thick ice layer generally making it a very high altitude area above the ice.
  • East Antarctic Ice Sheet
    This is considered most stable, as it is situated on high elevation ground, and extremely cold year-around.

Anyway, when you look at the map in the article linked above:



They seem to be discussing the area under the seasonal sea ice...  which lately has been generally stable as far as annual sea ice extent and loss.

This research should not be extended to any of the ice that is not floating. 

And, as always, this needs to be backed up with long-term recorded water temperature trends.  Without the long-term comparative data, it explains little more than the deep sea currents which we already know about.
 

Offline CliffordK

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When will Sea Methane Vapourise?
« Reply #10 on: 08/11/2011 23:52:54 »
It should be relatively easy to carbon-date the trapped methanogens and methyl hydrates which should give a map of the vulnerability of the various methyl hydrate reserves.  Unfortunately I've been unable to locate a comprehensive map of the age of the trapped methane.

This article notes that the methane trapped in some of the Russian permafrost bogs dates back 9,000 and 11,500 years ago to the early Holocene period (when there presumably was a temperature spike).

I don't believe any of the animals being discovered in the Russian permafrost date back to the pre-Eemian period. 

Anyway, one should be able to make a map.

Those methyl-hydrates that date back to less than 15,000 years would be most at risk, but perhaps also should be of least concern.

Those methyl-hydrates that date back to less than 100,000 years (post-Eemian) would be of moderate concern.

Those methyl-hydrates that date back to more than 150,000 (pre-Eemian) would be relatively stable.  Especially since the temperature maximum during the Eemian interglacial period was believed to be significantly higher than in the current Holocene interglacial period.
 

Offline yor_on

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When will Sea Methane Vapourise?
« Reply #11 on: 09/11/2011 09:42:20 »
Clifford, nice posts :) West Antarctica is what Hansen worried about already in the nineties. The mechanism by how that ice sheet may shrink is explained by lubrication from under it, moving it outwards into deeper water, where it then will break up into ice bergs that drift away with the winds and currents to melt. It's not only those underwater currents that can do it, you also have the 'ice streams' inside/under the ice that lubricates and moves the sheets. And ice is much more plastic that what we first thought, it adapts like some jello and will find the way 'down hill', much faster than expected when it starts moving. It seems to be a result of the bubbles trapped inside as I remember, that allow this shape changing.

As for how much methane is frozen into 'methane ice' I think you're right. Nobody can predict for sure how much there is, it's about getting as educated guesses we can. But so it is with most of our physics, even though the mathematics behind it might be impeccable there are always possibilities of something new, changing the whole picture. I know this will upset some, but history validates my opinion here.

This is from Natalia Shakhova and Igor Semiletov discussing the East Siberian Arctic Shelf (ESAS)

" Arctic Shelf and the Potential for Abrupt Climate Change (2010)."

University of Alaska, Fairbanks, International Arctic Research Centre, USA;
Russian Academy of Sciences, Far Eastern Branch, Pacific Oceanological Institute, Vladivostok, Russia;





"The East Siberian Arctic Shelf (ESAS) is 2.1×106 km2 area (~25% of the Arctic shelf, ~8% of the total area of the World Ocean’s continental shelf; 

~75% is shallower than 50 m  (mean depth of the continental shelf is 130 m)this provides very short conduit for methane to escape to the atmosphere with almost no oxidation.

The highest rates of carbon rain to the bottom provides required amount of organic carbon to be buried in the seabed; Annual sediment accumulation is about 10×1012 G Corg (Carbon ORGanics) yr-1, which approximately equals the amount of sediment accumulated over the entire pelagic zone of the World Ocean; Stable conditions of the continental margin lead to formation of very thick sedimentary basins (up to 20 km thick), which  provide temperature and pressure conditions required for methane production.

"Specific features of the Arctic shelf methane hydrates:

More sensitive to warming: because only 1/3 of energy required to convert deep ocean hydrates to free gas (54.2 kJ/mol) requires to convert to free gas Arctic hydrates (18,2 kJ/mol);

More vulnerable because they have naturally been experiencing warming by as much as 17˚C while deep oceanic hydrates were warmed by less than 1˚C;

More significant in their accumulations: because their spatial concentration is many folds greater as well as pore occupancy (20-100% vs. 1-2% of deep oceanic hydrates)

More potential for abrupt releases: Long-lasting permafrost impermeability determines huge potential of postponed emissions (alike pressure-cooker keeps all the steam inside till you."

So how far has it gone according to them?

A) Modeling results suggest that area of predicted taliks over the ESAS composes 3-5% of the total area Romanovskii et al., 2005).

B) Observational data suggest >80% of the ESAS East Siberian Arctic Shelf sea floor serves as a source of methane to the water column Shakhova et al., 2010).
 
Observed warming on the ESAS (March-April-May; MAM, 2000-2005 versus 1970-1999, NOAA) is the strongest in the entire Arctic and the region is now 5˚C warmer compared with average springtime temperature registered during the 20th century"

They also say that the area of open water in winter is increasing drastically. "Flaw polynyas (open sea water) start their formation in November, when wind breaks apart fast ice and drifting sea ice. Area of the ESAS open water in winter is equal to the total area of Siberian thermokarst lakes open in summer."

The bottom water in the ESAS has warmed, up to 3 degrees C, in the last three decades. As for how much Methane we're speaking of there?

"Accumulated methane potential of the ESAS:

1) Corg in permafrost ~500 Gt;
2) Methane accumulation in hydrate deposits ((gas hydrate stability zone) GHSZ=100m) ~1000 Gt;
3)Free gas beneath the GHSZ ~700 Gt;

OR:

Postponed emissions: 1 year – 8Tg (Tg=1012g); 1000 years – 8Gt (Gt=1015g); 90 000 years – 720 Gt;

And here is a map (not very clear, but still) showing the most probable locations of methane.



« Last Edit: 09/11/2011 09:47:00 by yor_on »
 

Offline Mazurka

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When will Sea Methane Vapourise?
« Reply #12 on: 09/11/2011 15:19:02 »
Yor-on, whilst I do not disagree with the hazard or the presence of clathrates in the Arctic ocean, I disagree with the potential risk posed as there is not enough infromation.  I am not aware of any atempts to constrain how much disolved methane is oxidised by other microbial activity. (Is such a process in some form of equilbrium with methane evolved?  Is it otherwise limited by temperature or nutrients?)   

I would sugest that the subject is quite complicated, with several different potential sources of methane - including marsh gas capped with ice in permafrosted blanket bog; shallow hydrates in polar oceans and deep hydrates on continenal shelves.

I would also suggest that citing research that does not relate (except in the most hypothecated way) to a central argument is one of the reasons that those that argue against anthropogenic global warming have such an easy time.

(Personally I am happy that the IPCC has a better handle on the issue of AGW than any one individual can possibly have and their forecasts are "the state of the art" this is not to say that things are cast in stone - the state of the art improves with every peer reviewed paper, merely that the our current "best" understanding, thus forecast modeling does not include the so called clathrate gun.)
 

Offline yor_on

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« Reply #13 on: 09/11/2011 17:04:40 »
Well, everyone has the right to their own opinion. What I presented is mine, and the material I've used comes from expeditions and research. Maybe we can wait for us to 'know it all', but I wouldn't bet on it :)
 

Offline yor_on

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When will Sea Methane Vapourise?
« Reply #14 on: 09/11/2011 18:52:20 »
By the way, methane clathrates can be formed at greater depths too, although what I was talking about here was the Arctic/Antarctic. There it is the cold that allows the methane clathrate to be so close to the surface, but.

Methane clathrate formation is considered in terms of water depth, temperature, and O2 concentration. There are three places to find methane clathrates:  oceanic sediment of continental slopes and rises greater than 300 m (ocean pressure is approximately 0.3 MPa) , deep-water sediment of inland lakes and seas greater than 300 m (where the pressure is approximately 0.3 MPa, and polar sediment of both continents and continental shelves. When the pressure is high (greater than 0.6 MPa) and temperature is low (less than 300 K), water can freeze and incorporate a fraction of produced methane. (1 MPa = 1×106 Pascals, 0.6 MPa is approximately equal to six times greater than the atmospheric pressure). 

Therefore, depending on the conditions, clathrate hydrates can exist at temperatures below or above the normal freezing point of water.  In shallow waters, clathrates most likely do not form below 600 m due to warm sea temperatures.  However, in the Arctic Ocean, clathrates form in only 250 m because of cold sea temperatures.  In deeper waters, methane clathrates are commonly found in depths of 1000 to 3000 m. At these depths, these clathrates are located in the top few hundred meters of marine sediment... 

Methane clathrates, as part of the global carbon cycle, can change with varying environmental conditions.  Methane can dissociate and leave the clathrates in sediment in two possible forms:  dissolved gas and bubbles. Dissociation which occurs through a change in temperature and pressure are usually considered the largest threats to methane clathrate stability. Methane clathrates dissociates rapidly under laboratory conditions because the temperature and pressure needed to maintain their stability is not found under standard conditions.  In their natural environment, methane clathrates also dissociate, but at a slower rate. Buffett and Archer (2004) indicate that changes in sea level have very little effect on the overall inventory of methane clathrates but a change in ocean temperature or oxidation could have a great effect on the dissociation of methane clathrates... 

Many other environmental concerns exist for methane clathrates besides the sudden release of methane to the atmosphere.  With approximately 90% of global methane clathrates occurring at depths of less than 1000 m, their stability is highly sensitive. A large concern is related to the sediment sections around and near the methane clathrates.  These large unstable volumes of sediment, methane, and water have resulted in huge slides off the Norwegian coastline. The movement of marine sediment (from the dissociation of methane clathrates or other physical changes) causes slumping, which can quickly release methane from the sediment (called outgasing). As a result of the displaced water from the slumping, tsunamis could develop.

One of the Norwegian gas-hydrate linked slides produced a tsunami which deposited sediment up to four meters above the high water line in Scotland. In addition, the quick release of methane is a big deal because methane has a very low water solubility (22 mg/L @ 298K). Thus, the methane would not be dissolved or oxidized in the water column when released, but would reach Earth’s atmosphere.  Zonenshayn et all in 1987, indicated that a “large pulsating gas plume” in the Sea of Okhotsk (located on the northwestern edge of the Pacific Ocean) was due to volcanic heating of overlying gas hydrates. Gas-driven eruptions are commonly known for lakes but are also possible for oceans.
 
Sudden releases of methane due to slumping or dissociation can not only cause atmospheric problems but also the cause of geohazards such as landslides, earthquakes, and tsunamis. The petroleum industry is seeking to search deeper for energy reserves, which produces a strain on the fragile depths of the ocean methane clathrates.   Kvenvolden in 2000 notes of the “superficial slides and slumps on the continental slop and rise of West Africa;
slumps and collapse features on the U.S. Atlantic continental slope; large submarine slides on the Norwegian continental margin; sediment blocks on the sea floor in fjords of British Columbia; and massive bedding-plane slides and rotational slumps on the Alaskan Beaufort Sea continental margin”.

Archer and Buffett (2005), found that an increase of methane in the sediment column from the bubbles could cause a series of oceanic landslides over a period of thousands of years. The dissociation of methane clathrates can also be caused by heat transfer during petroleum production and can cause collapse of engineering structures, such as platforms and pipelines. There is no doubt that many geohazards can be environmental dangers."

From 'Deep Ocean Methane Clathrates:  An Important New Source for Energy? by Justin P. Barry.

As for me citing the 'wrong research'. I don't think I do.
 
 
 

Offline CliffordK

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When will Sea Methane Vapourise?
« Reply #15 on: 09/11/2011 22:37:22 »
I agree that methyl hydrates likely exist in the polar regions at much shallower depths due to colder ocean surface temperatures than in equatorial regions where they can only exist in deep ocean sediments. 

And, those in shallow water are at greatest risk to melting due to surface temperature fluctuations.

Undoubtedly there are some methyl hydrates at the bottom of the Mariana Trench at 10+ km deep...  which would be perfectly safe from melting.

What we need is a better understanding of the age and quantity of methyl hydrates in each deposit to better understand what is at risk, how much, and what has happened in the past, for example during the Eemian interglacial period.
 

The Naked Scientists Forum

When will Sea Methane Vapourise?
« Reply #15 on: 09/11/2011 22:37:22 »

 

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