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:
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).
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.
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.