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Dr Graham Phillips Introduction: Carbon dioxide is synonymous with climate change but what about the other greenhouses gases that we hear little about. Dr Paul Willis reports on a gas that is 20 times more potent than carbon dioxide, and unleashed could have devastating consequences.


Narration: We know that global warming is complex.


Dr Evelyn Krull: We are not looking at the whole picture.


Narration: Perhaps we’re missing something important.


Dr Andrew Smith: Increased in concentration by something like two hundred and fifty percent.


Narration: A climate player with a murky past


Dr David Etheridge: warming the globe for very long periods.


Dr Paul Willis: When it comes to climate change, carbon dioxide gets all the attention, but these cows here are producing a greenhouse gas that is more potent than carbon dioxide. It’s a gas that’s been implicated in the greatest mass extinction of all time, and we’re pumping it out at an ever increasing rate.


Dr Etheridge: It has some fairly complex roles in our climate and in the chemistry of the atmosphere.


Dr Smith: It is an important player.


Narration: It’s methane, the forgotten greenhouse gas. And it’s a gas that’s surrounded in myths. Contrary to popular opinion, it doesn’t smell, and no, it’s not a major component of farts. More methane is actually pumped out from the other end… In fact one cow can belch out an astounding 700 litres of methane in a day! But there are many other sources of methane…


Dr Smith: The sources of methane can be broadly categorized as biogenic, of biological origin, pyrogenic, which is basically combusted biomass, and fossil sources.


Narration: Some of the methane in the atmosphere today has natural origins. But more than half of it was put there by us… And of that landfill, agriculture and mining account for about a third each. The atmospheric methane concentration today is just under 2 parts per million compared to carbon dioxide which is currently 384 parts per million. But atom for atom methane is far more potent than CO2 and it accounts for a whopping 20% of the green house warming effect. Working out where atmospheric methane has come from is a tricky business but it is a vital part of developing strategies to control it.


Dr Etheridge: So one way we do it, is we take air off the roof there, down a line, into a pump, and then take it over here where we analyse it for Methane.


Narration: Dr David Etheridge measures air samples from the roof of his CSIRO lab in Melbourne.


Dr David Etheridge: This is the methane concentration right now from above our roof top.


Narration: And with new technology they are now able to analyse bottled atmosphere from this library of air archive. Some of these canisters were stored 30 years ago.


Paul: This is the oldest specimen it comes from Cape Grim and it was collected in 1978.


Dr Etheridge: These are remote stations which have been placed to capture air coming off oceans, which is pretty much what we call background or baseline air.


Narration: So what’s the picture so far?


Dr Etheridge: From 1978 onwards (the earliest measurements) there was a rapid increase in methane concentration.


Narration: And this was mainly because of an increase in agriculture and industry. But then something unexpected happened –


Dr Etheridge: Methane has stabilized in concentration ah beginning in about 1999. And it wasn't too clear what that was…


Narration: We’ll deal with the future of methane later, but how do we investigate what happened prior to 1978? The answer is trapped in ice.


Dr Smith: That’s a nice sample.


Narration: CSIRO scientist, Dr Andrew Smith and his colleagues have been drilling ice cores in Antarctica as well as recovering samples from Greenland. And the challenge is enormous …


Dr Andrew Smith: Aiming to produce a five microgram carbon sample after having liberating the air from a hundred kilograms of ice - this is tough.


Paul: This is a cut section of the ice core, and you can actually see the tiny bubbles of ancient atmosphere that these guys are interested in.


Narration: After painstakingly extracting the methane gas from the ice core, it’s converted into carbon, and then, it’s ready for analysis.


Paul: This is ANTARES the Australian National Tandem for Applied Research. It’s an extremely accurate atom counter and it’s just the tool you need to work out the history of methane in the atmosphere.


Narration: Samples are mounted on a sample wheel, ionised, accelerated, have their polarity reversed, stripped of their electrons all in a trillionth of a blink of an eye and they end up here.


Paul: So how sensitive is this? How many atoms can you count?


Dr Smith: Well this equipment, it gives us the ability to detect just one carbon fourteen atom in amongst ten to the sixteen stable carbon atoms. That's a very big number. Ah it's equivalent for example to finding one yellow grain of sand in amongst twenty tons of orange sand.


Paul: One in a gazillion.


Narration: Thanks to the work of scientists around the world, we can now track the history of atmospheric methane back some 800,000 years. Generally levels go down when there’s an ice age and they come up again in the interglacial periods. But something alarming has happened to methane levels since the beginning of the industrial revolution.


Dr Smith: The methane concentration has increased by two hundred and fifty percent over the agro-industrial period.


Narration: While that rise is alarming and its consequences unknown, there is an upside to the methane story. We can do something about it – by harnessing its energy.


Paul: Most of the methane in the atmosphere today has been put there by humans through landfill, coal mining, agriculture and other activities; But unlike CO2 it’s relatively easy to capture methane before it gets loose… and it pays to do so.


Narration: As the rubbish decomposes methane is released and captured in these pipes. It’s then pumped to this power station. The energy generated here has the potential to provide electricity to 16,000 homes… and even though CO2 is being produced in the process, the original methane is 20 times more harmful as a green house gas. While it looks like we can control the release of methane from some sources we shouldn’t be too complacent. There could be a spectre of doom lurking, a vast hidden source of methane… They’re called clathrates. It’s methane that’s been locked inside the crystal structure of water ice. They are found around the continental margins of oceans and polar regions, in very cold, high pressure conditions. They’re also locked up in the frozen tundra…


Dr Smith: There's an enormous amount of this stuff. Something like five thousand gigatonnes of carbon locked up as methane clathrate. That's about the same as all the carbon that's locked up in oil, gas and coal reserves.


Narration: But if temperatures rise or if the tundra melts they could be destabilised, releasing massive amounts of methane.


Dr David Etheridge: So you'd only need to release one percent of them and you have multiplied your atmosphere by about ten times concentration of methane.

Catalyst: Methane - The Forgotten Gas - ABC TV Science

This is (potentially) huge. Potentially, because the reports remain spotty on some critical details. Most important question: is this coming from frozen methane hydrates? If it's not, the potential release of methane could be bad, but probably something we could deal with. If it is... we're in a lot of trouble.


Here's why: according to (soon to be published) details about the region, that's 50 gigatons of methane that could be released. And methane, as has been reiterated time and again, is 23 times more powerful a greenhouse gas than CO2.


Except it's not. It's actually worse. That 23x figure refers to the impact of a given quantity of methane over a 100 year period -- a standard way of comparing the effects of different gases. But methane cycles out after a decade, so a better way of comparing its impact is over a shorter time period -- say, 20 years. Compressed to two decades, then, the relative power of methane as a greenhouse gas is 72 times that of carbon dioxide.




So that 50 gigatons of methane? That's the equivalent of 3600 gigatons of carbon dioxide, in terms of greenhouse effect.


To put that into comparison: the Earth's atmosphere holds a total of about 3000 metric gigatons of carbon dioxide.


This would more than double the concentration of CO2e in the atmosphere.


So this is not just huge, it's really freaking huge.

Open the Future: Methane: It's Not Just From Your Cheeseburger


As shown by a chemistry "ball and stick" model, a methane molecule is composed of one atom of carbon surrounded by four atoms of hydrogen.


Methane hydrate consists of a cage of water molecules trapping a methane molecule within. This can form large crystals of hydrate in cold and heavily pressurized situations (mainly on the continental slope in the oceans). (Image: Slim Films for Suess et al., Scientific American, Nov. 1999, pp. 76-83).

Methane Clathrates and Climate


Clathrates are a class of compound that consist of a cage of molecules that can trap gases, such as methane, in a solid form. For methane, the most important "cage" is one that is made of water molecules, and so is described sometimes as a hydrate. Some key facts about clathrates make them particularly interesting to climatologists.

First, they may make up a significant portion of total fossil carbon reserves, including coal and oil. Current best guesses suggest that maybe 500 to 2000 gigatonnes of carbon may be stored as methane clathrates (5-20% of total estimated reserves).

Some estimates are as high as 10,000 gigatonnes. They occur mainly on the continental shelf where the water is relatively cold, there is sufficient pressure and enough organic material to keep the methane-producing bacteria happy. Most importantly, clathrates can be explosively unstable if the temperature increases or the pressure decreases — which can happen as a function of climate change, tectonic uplift or undersea landslides.


The importance of these clathrates in climate change has only recently started to be appreciated. The first clue was some puzzling data from a period 55 million years ago. In the early 1990's, Jim Kennett of Scripps Institute of Oceanography and his colleagues noticed that during an extremely short amount of time (geologically speaking) at the transition between the Paleocene and Eocene epochs, carbon isotope ratios everywhere (the deep sea, on land, at the poles and in the tropics) suddenly changed to favour the lighter 12C isotope of carbon at the expense of 13C. The rapidity and size of this change was unprecedented in the period since the demise of the dinosaurs, and this excursion was simultaneous with a short period of extreme global warming (around 3 to 4 degrees globally, more in the high latitudes).

NASA GISS: Research Features: Methane: A Scientific Journey from Obscurity to Climate Super-Stardom

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Methane Cathrates, it sounds like a disease that Preparation H should cure. Methane cathrates have been a concern of mine since I saw evidence that huge amounts of MC could be the cause of loosing ships in the Bermuda Trianglethis was in the early 80's. I started looking and found evidence that massive bubbles of MC have been erupting in historical times from the ocean bottom just off shore of where I live. In the North Atlantic there are huge holes in the ocean bottom thought to be the result of huge releases of MC. Methane is a super greenhouse gas and it consumes oxygen as well. Greenhouse warming could release so much of this gas it could change the very composition of our atmosphere and make it difficult to breath not to mention hot enough to make it difficult to live. This has been one of the reasons I am so rabidly pro nuclear power. No matter how you explain global warming the increase in temps threatens to release megatons of MC and this could indeed end our civilization. We as a civilization need to take steps to mitigate this problem. It probably wouldn't end life on Earth but it does have the power to end human life on earth.

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i was promted to start this thread when i read a letter to the Editor in the local paer insting that methane was NOT agreen house gas.


The Methane Clathrates were a nasty suprise.


The seafloor off Santa Barbara just burped up a huge eruption of methane - and scientists caught it on video. Now, at about 5,000 cubic feet at the surface, this methane cloud was huge by people-watching-with-videocameras standards. That’s not to say massive by vast-limitless-ocean standards. But still, it gave the scientists a chance to do some number-crunching on an imaginary massive eruption of methane.


And why are the scientists stretching their imaginations in this way, you might ask? Well, it turns out that there are actually massive (not just huge) deposits of methane on the ocean floor (and in Arctic permafrost, too, but that’s another story). The ocean deposits are quiescent at the moment, frozen into sort of waterlogged crystals called methane hydrates, a.k.a. clathrates (here’s a bit more blogging on clathrates).

Pulling the Clathrate Trigger surf.bird.scribble.


Gas Hydrates (Clathrate Hydrates)

Clathrate hydrates constitute a class of solids in which the guest molecules occupy, fully or partially, cages in host structures made up of H-bonded water molecules. The usually unstable empty clathrate is stabilised by inclusion of the guest species. In case of guest molecules which are gaseous at ambient conditions the resulting clathrate hydrate is often called a gas hydrate. These compounds are interesting for several reasons: much could be learned about water-water interactions in these topologically rather complex systems, especially if one could follow the pressure dependency of the host structure over a wide pressure range. Likewise, much could be learned about the guest-host interactions in a wide range of guest species from noble gas atoms to large (and polar) organic molecules. Clathrates are believed to occur in large quantities on some outer planets binding gas at fairly high temperatures, which is an interesting issue for planetologists.

Werner F. Kuhs: Clathrate Hydrates

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