I agree with iceaura's post 381 comments, but also note that this link is a well documented statement basically to the effect that something like 99% of the methane hydrates will not become unstable for at least 103 years. One can not rationally take any more comfort in that than in the statement that 99% of the existing nuclear bombs will not be fired in an all out nuclear exchange as the first 1% will so disrupt the command and control systems that the safety controls, release codes, etc. can not be delivered or, if delivered, exercised (all already dead at the surviving silo site, etc.). Here, in blue, is most of the link's conclusion:
"
Catastrophic*, widespread dissociation of methane gas hydrates will not be triggered by continued climate warming at contemporary rates (0.2ºC per decade; IPCC 2007) over timescales of a few hundred years. Most of Earth’s gas hydrates occur at low saturations and in sediments at such great depths below the seafloor or onshore permafrost that they will barely be affected by warming over even 103 yr. Even when CH4 is liberated from gas hydrates, oxidative and physical processes may greatly reduce the amount that reaches the atmosphere as CH4. The CO2 produced by oxidation of CH4 released from dissociating gas hydrates will likely have a greater impact on the Earth system (e.g., on ocean chemistry and atmospheric CO2 concentrations; Archer et al. 2009) than will the CH4 that remains after passing through various sinks.
Contemporary and future gas hydrate degradation will occur primarily on the circum-Arctic Ocean continental shelves (Sector 2; Macdonald 1990, Lachenbruch et al. 1994, Maslin 2010), where subsea permafrost thawing and methane hydrate dissociation have been triggered by warming and inundation since Late Pleistocene time, and at the feather edge of the GHSZ on upper continental slopes (Sector 3), where the zone’s full thickness can dissociate rapidly due to modest warming of intermediate waters. ... "
* Clear from the text and even in the part of the conclusion, I made bold, that
his "Catastrophic" means / is when a large fraction, (not just ~1%, of the methane hydrates), is released in less than 103 years. A mere 1% "burp" released over a decade, which would only produce NTE (Near Term Extinction), and does not qualify as "Catastrophic." With this definition of "Catastrophic" , I agree, "Catastrophic" methane release from the deep, pressure-stabilized, methane ice hydrates is impossible in the next 103 years.
When little dog Toto of Wizard of Oz pulled the curtain back, the "Wizard" said: "Pay no attention to that man behind the curtain." Unlike Toto, I can type, so say:
"Pay no attention to assurances that "Catastrophe" is impossible because neither 99% of nuclear nor methane ice hydrates "bombs" will explode in the next 103 years."
Also very miss-leading and falsely reassuring is the "denier's" reassurances of no danger based on true facts that life has made it thur ancient periods when CO2 was much higher than current levels. This high level of CO2 developed over many thousands of years, not the current rapid rate. Thus every century a little more methane was released, and quickly oxidized to water and CO2, so the CH4 concentrations were not as high as they currently are. Back then natural processes could and did produce the OH radial, main destroyer of tropospheric methane. I.e. the half life of newly released methane was certainly less than one year with OH radical at it's dynamic steady state concentration. Now the rate of CH4 release is so rapid the OH radical concentration is much lower and dropping. I.e. the half life of CH4 about a decade ago (in 2004 as I recall) was 9.6 years but in 2013 was 12.6 years and still increasing.
SUMMARY: Back when CO2 was much higher than now, methane concentrations were much lower and rapidly being converted to an insignificant part of the CO2 concentration. Now methane has entered into a positive feed back system: More GW, more CH4 released each year, so more OH radical destroyed each years with OH concentrations falling, so every CH4 molecule last longer (about 0.3 years per year now) and more are being release this year than last year. - more living longer is a very strong positive feed back system and already in the first 10 years, it takes 104Kg of CO2 to do the same GW, averaged over those 10 years, that one Kg of CH4 does. (assuming falsely that the current OH radical were not being reduced).
This positive feed back system mainly operates in the Arctic, and strongly re-enforces the melting sea ice positive feed back system (Floating ice reflects more than 80% of the incident sun light, but when that area has open water instead of ice more than 80% of the sun light is absorbed in the sea to melt ice every more rapidly.) Also as the wind now has larger open sea to build strength, the waves are larger and stronger so the thinned ice still un-melted is broken up and melts faster. There are a total of 34 known mutually re-enforcing positive feed back systems. Almost none of which were even significant positive feed systems back when CO2 took thousands of years to increase as much as it now does each decade!
