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Tuesday, December 13, 2011

Natalia Shakhova Science interview, June 2011, on subsea permafrost and "ready to go" methane

Shakhova Interview

This week’s Science podcast features Shakhova discussing the team’s findings. transcript

…subsea permafrost acts as a lid – the seal to prevent this methane escape. And being prevented for a period of time, being sealed for a period of time, means that this gas accumulates, and it accumulates under higher pressure –- this is what we have to give an example, this is what we have, for example, this bottle of champagne. So, you have a lot of gas inside, but it’s sealed for a period of time, and when you uncork this bottle, what you can see – it’s different from a bottle of mineral water left open for period of time, it’s just little bit of different. And I think that release of methane from this kind of seabed deposits disturbed by destabilization of subsea permafrost, provides a pathway for this methane – ready to go methane – because its release does not depend on production. It’s not time-dependent, it’s not temperature-dependent, it only needs the pathway to be released.

So, what we estimated recently is our first approach – we developed this original approach to incorporate two different components of emissions. And the initial numbers we currently reporting doesn’t sound alarming – this is between the 6.5 teragram a year to 10 teragram a year. And this is initial numbers, and we did not incorporate [a] few very important components of emission, which being incorporated might change our first estimate significantly, because what we did not incorporate is nongradial emission – nongradial, sudden or kind of outbursts-like emissions, which [are] usually associated with methane emission as bubbles from the seabed through the water column and directly into the atmosphere, which is associated with destabilization of seabed deposits, I think.

So the 8 teragram figure is just the estimate of the gradual component of the release, not the total annual release from the shelf.

And for me, destabilization of subsea permafrost not even everywhere because, for example, we have areas – fold zones, reef zones, tectonically active areas and so on – and destabilization of hydrates, if it takes place, also can simulate kind of endoseismic events due to sediment settlement and adjustment. And this is not even a gradual process, as every physical process when you go from one stage to another stage, it’s never even – it’s kind of jump start. It’s, for example, when you see one day when it is ice break time, and you see one day in the evening you see the huge lake covered with broken ice. And the next morning you cannot see a single piece of ice on this lake – that means that the melting of this ice reached the melting or thawing point, and it just jump into the next stage, which is fluid.

Interviewer – Robert Frederick
So, it sounds as if it’s not a linear process – it could become…

Interviewee – Natalia Shakhova
It’s not, it’s definitely not a linear process – this is what I mean, it’s not linear. That’s why establishing this first numbers, first estimates, this is just very first phase in our work. But now, we are thinking of providing details, and we do have some materials already from 2009 expedition, which we are just very are anxious to prepare for publication. But, speaking of this current paper, this is what my thoughts [are] about.

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