What is the methane hydrate threat from global warming?
Since at least 1992 (US GS report) scientists have regarded methane hydrate as a potential huge source of fossil fuel energy and a catastrophic potential climate change danger. The risk of global climate catastrophe has been dismissed as 'uncertain' or 'unlikely' till recently .
This dismissive attitude in science publications and opinion on the risk prevails to this day and methane from hydrates is planned to enter the worlds natural gas supplies in just a few years.
In a 2006 report risk analysis for the German Advisory Council on Global Change Davod Archer said that
The risk of climate impact in the coming century from the methane hydrate reservoir is speculative but could be comparable to climate feedbacks from the terrestrial biosphere and from decomposition of melting peat deposits. This is at least 2C by 2100.
"Methane hydrate seems intrinsically vulnerable on Earth; nowhere at the Earth's surface is it stable to melting and release of the methane, and it floats in water, so the only factor holding it at high pressure is the weight of the mud overlying it in coastal margin sediments. A few degrees of warming in the deep ocean can have a significant impact on the stability of the hydrate, and it is known that the temperature of the deep ocean responds to changes in surface climate, albeit with a lag of centuries to millennia. Hence, there are concerns that climate change could trigger significant methane releases from hydrates and thus could lead to strong positive carbon-climate feedbacks (Schiermeier, 2008)." David Archer, 2009, Gas hydrates: Entrance to a methane age or climate threat?
Global warming through ocean warming will, when the sea floor is warmed up enough, destabilize methane hydrates, releasing methane gas. The feedback is shown by a 2006 global warming assessment for the German government (see chart to the right).
It is estimated that if 10% of methane stored in permafrost was released into the atmosphere, it would have an effect similar to a ten-fold increase in CO2. Abrupt warming would occur if the concentration of methane, or CO2, increased suddenly; this would in turn cause further melting of permafrost and release of even more ancient methane deposits; and therefore it would intensify global warming even further. This phenomenon is known as a "positive feedback." Even if methane accumulates at a slower pace, it will still intensify global warming by oxidizing to CO2, which is a less potent greenhouse gas but with a much longer lifetime (a mean of 100 years).
Where are methane hydrate deposits situated?
Vast quantities of methane are stored in terrestrial and underwater permafrost. Methane deposits in frozen underwater sediments are found along the outer continental margins where there is ample organic matter supply (deposited over many thousands of years by rivers) and low water temperature.
Methane hydrates are known to occur both within and below permafrost in polar areas. Several areas in the Arctic show potential for having gas hydrate accumulations. Three areas are in North America and four are in Russia: (1) northern Alaska, (2) the Mackenzie Delta-Beaufort Sea region, (3) Sverdrup basin of Canada, (4) Western Siberia basin, (5) Lena-Tunguska province (Vilyuy basin), (6) Timan-Pechora basin, and (7) several sedimentary basins in northeastern Siberia and the Kamchatka area. Additionally, (8) the Svalbard archipelago (Norway) and (9) sedimentary basins under the ice cap of Greenland (Denmark) may have pressure and temperature conditions favourable to the formation of gas hydrates (US Department of Energy).
"'Promising energy inventories' of methane hydrates have been described in Alaska, Antarctica, the Canadian Arctic, India, the continental shelf off Japan, Nigeria, the South China Sea, Norway, Peru, and Australia. Most promising for the US are Alaska’s North Slope, Blake’s Ridge, and the Gulf of Mexico.”
In the cold Arctic waters, methane hydrate can form under relatively lower pressure than other regions and so occurs in shallower water, making it stable but particularly vulnerable to global warming, which destabilizes the solid hydrate, releasing methane gas. It is especially vulnerable in the shallow East Siberian Arctic Shelf (ESAS), where 90% of Arctic methane hydrates are situated.
Unexpectedly, a team of Russian scientists researching Siberian methane emissions have been discovered methane gas venting from methane hydrate below the East Siberian Arctic shelf.
Large methane releases erode the ocean’s ability to consume methane released from hydrate.
large methane releases erode the ocean’s ability to consume methane. Methane hydrates will destabilize as the Arctic ocean continues to warm. The simulation shows oxygen levels in the ocean plummet and acidifcation rises. “The amount of methane entering the ocean is huge and it changes the water chemistry dramatically.... It consumes oxygen, the microbes stop eating, and methane can reach the surface.... Large-scale methane releases have a greater impact than we anticipated.... When this happens, microbes cannot consume all of the methane because there isn’t enough oxygen to fuel them."
Methane hydrates and past extinction events
Methane hydrate is the most likley source of large atmospheric increase at the paleo-eocene thermal maximim (PETM) extincion 55 million years ago
How was methane hydrate created?
Most methane gas hydrate was produced by the anaerobic decomposition of organic matter dating back to the Pleistocene age. When the temperature is around the freezing point of water and the pressure is extremely high (26 atmospheres or more), methane combines with water and condenses into methane hydrate, which looks like dry ice. The formation and occurrence of gas hydrate is controlled by formation temperature, formation pore pressure, gas chemistry, pore water salinity, availability of gas and water, gas and water migration pathways, and the presence of reservoir rocks and seals. Essentially, methane hydrate forms under a combination of high pressure and low temperature limited in a particular situation with a "stability zone."
Arctic continental shelf methane hydrate has been warming extremely slowly from deep earth heat below the sediment ever since the retreat of the last ice age.
What is methane hydrate?
Frozen solid pressurized methane gas hydrate in ice- descibes its features A Good explanation is at World Ocean Review Climate Change Impacts on methane hydrates
How much methane hydrate is there?
Marine sediments contain about 500–10,000 Gt of methane carbon, primarily in gas hydrate. This reservoir is comparable in size to the amount of organic carbon in land biota, terrestrial soils, the atmosphere and sea water combined (John W. Pohlman et all Nature 2010)
Estimates vary greatly being based on theoretical suitable regions of water temperature and pressure (10.000- GT carbon Univ Washington). Latest research off the coasts of Oregon and of Russia and of Japan indicates there could be much more going by conditions suitable for hydrate formation.
The Arctic is estimated to contain up to one third of global deposits (US D.Energy) and N Shakhova's figure is not less than 1400 Gt.. Global estimate is put at more than all fossil fuels combined. 2,500 gigatonnes of carbon - 3X atmospheric carbon). Release to the atmosphere of only 0.5 per cent of Arctic the Arctic shelf hydrates could cause abrupt climate change.
Antarctica has methane deposits, potentially in enormous amounts.
Methane gas has 160 x the volume of the solid hydrate containing it, and therefore methane hydrate destabilization will tend to be explosive — on a large or small scale. An MIT model has found this effect and it has been suggested that this property makes the hydrates more vulnerable to warming because destabilization could be self propagating. "This indicates that we may be greatly underestimating the methane fluxes presently occurring in the ocean and from underground into Earth's atmosphere" (Ruben Juanes, 2009 MIT energy research).
A 2010 review by Masin et al (Gas hydrates: past and future geohazard?) of the global threat from methane hydrate on a global basis found global warming could result in hydrates emitting methane from around continental coasts, the Arctic, Greenland and Antarctica; the Arctic being the most definite danger. . Models of the global inventory of hydrates and trapped methane bubbles suggest that a global 3C warming could release between 35 and 940 GtC, which could add up to an additional 0.5◦C to global warming.
The final conclusion is "more research is required to (i) quantify the amount of methane stored in and below gas hydrate deposits and (ii) increase our understanding of the possible limits of stability of these deposits, before we can successfully evaluate the future risk they pose to both the local and global environment." So much for precaution in avoiding catastrophe.
The 2008 US Abrupt Climate Change Synthesis found that "acceleration of persistent release
from hydrate reservoirs is likely, but its magnitude is difficult to estimate."
\A comprehensive online scientific book about methane catastrophe, by Dr. Dan Dorritie
2010 Methane released from ocean hydrates is a cause
For many years and to the present day scientists have viewed methane hydrates as an : entrance to a methane age or climate threat? This 2009 paper by V, Krey J Canadell N Nakicenovi D. Archer & 13 others comes down in favour of using methane hydrate as a fuel.
It has been assumed that methane hydrate may have been a source of huge atmospheric increases at the time of mass extinction events. There is more direct evidence of the potential from research New Zealand: Evidence of massive release of methane from hydrates. However methane hydrate scientists say that the largest global temperature increases cannot be explained by methane hydrate. Research of 2011 of large methane releases on the atmospheric chemical interactions suggest methane hydrate could have the cause.
Methane hydrate self preservation may make the hydrates even more vulnerable,
This 2010 Royal Society paper cites the risk of global warming detonating methane hydrates by melting ice sheets and the risk that methane hydrates can cause tsunamis.
Evidence for large methane releases to the from deep-sea gas-hydrate dissociation during the last glacial episode. PNAS 2004 Thibault de Garidel-Thoro
What is not known is how fast the methane will be released and hom could reach the atmosphere.
In a 2009 presentation James Hansen says global warming is a 'time bomb' because of tipping points in the climate system, one of which is frozen solid pressurized methane gas hydrate. They exist round continental shelves world wide, but the most dangerous are Arctic.
In a 2007 paper James Hansen said that the tipping point for methane hydrate is 1.6C warming greater than 1C (more) raises the likelihood of a large positive feedback from methane hydrates.
Siberian Permfriost craters There is methane hydrate very deep below land
permafrost, assumed to be too deep for destabilization by surface warmin\g,
but Russian scientists on the spot say this is the cause for the apperwnce of
large permafrost craters on the Siberian Yamal peninsula. .
2012 research Atmospheric impacts and ice core imprints of a methane pulse from clathrates shows evidence of large methane hydrate outgassingsd and larger ones cannot ecluded because of ice core smoothing.
2010 Climate change impacts
on meathe hydrate
Feb 2008 Possible Origin Of Methane In Ice Core Records
Aug 2014 Widespread methane leakage from the sea floor on the northern US Atlantic margin.
Aug 2014 Widespread methane leakage - sea floor Northern US Atlantic margin Science
Dec 2014 Dissociation of Cascadia (N.west Pacific N America) margin gas hydrates in response to contemporary ocean warming
22 Sept 2015 Danger of methane explosions on Siberian Yamal Peninsula, scientists warn
July 2013 Offshore permafrost decay and massive seabed methane escape in water
depths >20 m at the South Kara Sea shelf. Alexey Portnov
14 Jan 2019 Past (17K yrs ago) ocean methane venting
June 2016 Methane Hydrate: Killer cause of Earth's greatest mass extinction