Methane hydrate column

In the article “It’s a gas” on the website slweekly.com ( http://www.slweekly.com/editorial/2007/straight_2007-08-02.cfm ), Cecil wrote about oceanic methane hydrate deposits, but he neglected to fully cite the estimated 400 billion tons of methane (CH4) in permafrost deposits.

The reason those deposits of methane hydrate (for the sake of brevity I’ll skip explaining about methane hydrate-see the article) in permafrost are important is that the National Center for Atmospheric Research (NCAR) estimates that half of the surface permafrost will melt by 2050, and over 90% by 2100.

By the way, a sudden release of less than 30 billion tons of methane into the atmosphere would be like doubling the CO2 level in the air.

To be fully honest, a newer paper published in the Geophysical Research Letters (Vol. 34, 2007) titled “Near-surface permafrost degradation: How severe during the 21st century?” contradicts the NCAR model. In my opinion, this newer model is inaccurate for three reasons:

  1. It doesn’t take into consideration radiant heat (i.e. after the shiny snow melts from over the permafrost, the darker earth absorbs the radiant energy of the sun).

  2. It doesn’t take into consideration the positive feedback loop of the melting permafrost emitting greenhouse gases leading to more regional warming and to a more rapid melting of permafrost.

  3. It doesn’t take into consideration the paleoclimatological evidence of rapid temperature rises associated with previous permafrost melting episodes.

Anyways, the speed at which that permafrost melts is crucial in determining the temperature at which dangerous melting occurs. In Siberia alone, there is a patch of permafrost the size of Germany and France combined, the methane level there is reported to be 20 times normal, and it has seen one of the biggest temperature rises on the planet.

Dr Hansen from NASA bases his red-line at 450 ppm of CO2 (or about a 1C further rise in temperature) on the effect it would have on the speed of permafrost melting.

The theory is that our emissions would act like a fuse that would ignite the detonator of permafrost methane hydrate deposits, which would set off the bomb of oceanic methane hydrate deposits (estimated at abou 10,000 billion tons of methane).

By the way, rarely do people bring up the crucial factor of shallow oceanic methane hydrate deposits. A temperature pulse would have to be really large (about 6 C air temperature rise), and take a long time, to reach down to the deep ocean where most of the methane hydrate is. On the other hand, there is a small fraction (i.e. a small fraction of 10,000 billion tons is still a very large amount) located in shallow water off shore in the ocean.

Last year there was the smell of natural gas (i.e. rotten egg smell put into natural gas to warn us of leaks in pipes) in Manhattan, New York. I bet that was methane hydrate melting and bubbling up from off shore. There has been reports of “explosions” heard on shore around the world from the ocean that could be the start of methane hydrate melting and bubbling up (it shoulds really loud when it cuts loose-the same principle as people farting).

Remember just a sudden release of 30 billion tons would be like DOUBLING the CO2 level of the air. Even a “little” release, combined with mankind’s already enormous greenhouse gas emissions, could be big big trouble.

To summarize, while the sexy subject of oceanic methane hydrate deposits is fully discussed in Cecil’s article, the less stunning, but more immediate subject of melting permafrost methane hydrate deposits is mostly neglected. The fate of our civilization and climate could well hang on the speed at which methane hydrate deposits in permafrost melt.

I think you might not have written what you intended. Unless the methane hydrate release was coincident with a sulfur-based compound release, it is highly unlikely that methane hydrates would produce the same smell as ethyl mercaptan, the compound which gives natural gas its odor.

IIRC the explosions often heard on the East coast of the US (similar, some say, to the creepy “Seneca Guns”, which I’ve interviewed local residents about for my own personal research), are most likely thought to be the result of tectonic stress, or other geophysical phenomena. However, there is a school of thought that large methane or other gaseous eruptions could be the driver behind the sounds. I don’t think that is likely to be determined anytime soon, unless some sort of real-time monitoring of multi-level atmospheric methane is focused on those areas.

What I’d like to know is the answer to a question that popped into my mind after reading this in the column:

Since this happened 8,000 years ago, what physical evidence was left behind that led scientists to say that the tsunami was 13 feet high, and not 12 feet or 14 feet?

The coast of Scotland is pretty big, and highly irregular (lots of “crinkly bits”). That’s obviously an average figure.

What was up with the little reference to the Bermuda Triangle? I thought Cecil himself had a column explaining that the statistics for this area show no more loss of ships then is to be expected for the size and traffic in the area.

Was he just being cute?

If so, he left a dangling morsel for the crazies to use to quote him.

Jim

I miss the good old days, when the only external force likely to kill me was the USSR.

I’m guessing he’s referring to the fact that even though statistically speaking the Triangle isn’t so scary, some folks contend that methane gas eruptions could be responsible for ship losses in the Triangle area. They even insist that giant methane eruptions could be responsible for plane losses, with the plane flying through the cloud and igniting it…

Methane is not completely stable in the presence of oxygen; even the current level of methane in the air is higher than equilibrium because of gas continually released by swamp bacteria and farting cows. Does anyone know how long even a big one-time methane release would screw up our climate before it oxidized away to nothing (well, CO[sub]2[/sub] and water)?

Ah, thanks for the clarification. I can just see some nutter thinker that, that sentence means Cecil is entertaining that maybe the Bermuda Triangle theories have merit.

Jim