Climate Emergency Institute
Climate Science Library
Methane gas hydrates: A potential threat to climate stability
George Papadakis, UK
Original Post: Dec. 22, 2011

What is methane hydrate?

The term ‘clathrate’ is used to describe a situation of non-bonding molecules that co-exist on a host/guest relationship. It is used specifically to describe “the inclusion of molecules of one kind within the crystal lattice of another” (Webster, 1994). ‘Hydrate’ is a term used to describe a special case of Clathrates where the host molecule is water and the guest molecule is a gas. Therefore, when we speak of methane gas hydrates, we refer to methane gas occupying the lattices of the crystalline structure of frozen water .

How was methane hydrate created?

Methane gas in hydrates has been 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 atmosphere or more), methane combines with water and condenses into methane hydrate, which looks like dry ice[…]Review of previous gas hydrate studies indicates that 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 ”.

Where does methane hydrate exist?

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 and very low water temperature. “Promising inventories of methane hydrates have been described in Alaska, Antarctica, the Canadian Arctic, and 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 ”.

How much methane hydrate is there?

Scientific consensus currently holds that the global quantity of methane hydrate amounts to 21 x 1015 m3. This estimate has been made independently by Kvenvolden (1988) and Macdonald (1990). Other estimates, both larger and smaller from the consensus estimate, have been made by other scientists. These lie between 1 x 1015 m3 (Ginsburg and Soloviev, 1995) and 139 x 1015 m3 (Gornitz and Fung, 1994). Harvey and Huang (1995) proposed a few estimates but chose 46 x 1015 m3 as their best one. It is likely that the global amount of methane in gas hydrates exceeds 1015 m3 but that it is less than 1017 m3 “with the actual value in the lower or intermediate part of the range ”.

The quantity of methane stored in the ocean seabed has been estimated to 10,000-11,000 Gt C . It is estimated that in Siberia alone there are 1,400 billion tons of methane gas hydrates . Although there are methane deposits in Antarctica, estimation about their quantity has not been proposed yet. There is believed to be significantly more methane in oceanic gas hydrates than in arctic ones .

The image below shows the available carbon content in methane hydrates in comparison to other carbon sources, including fossil fuels.


​​​Figure 1:



How is methane hydrate threatening climate stability?

Frozen water containing methane gas is either already melting or in immediate danger of melting due to global warming. As permafrost thaws, methane gas that had been safely trapped in the ice is escaping to the atmosphere. The warming of the oceans is also causing methane to be released from underwater permafrost.

Thawing of permafrost followed by an increase in methane concentration has been observed by scientists in Alaska, Siberia and the Arctic. Scientists have also observed methane leakages from the ocean floor off Norway that is believed to be occurring due to recent warming of the ocean . Methane that leaks from the ocean floor was previously thought to dissolve in the water and converted to CO2 by chemical reaction; however a study commissioned by WWF showed that some of the methane escaping from the shallow depth of the arctic shelf reaches the atmosphere without dissolving . “While most of the methane currently released from the seabed is dissolved in the seawater before it reaches the atmosphere, methane seeps are episodic and unpredictable and periods of more vigorous outflow of methane into the atmosphere are possible ”.

Deferred over 100 years, methane is 25 times more potent than CO2 as a GHG but methane lasts in the atmosphere about 12 years. The IPCC gives a methane global warming potential of 72 over 20 years and over 10 years it is 100 times CO2. Methane is classified as a long lasting atmospheric GHG by the IPCC. However methane emissions carry on heating after 12 years because this life time is due to atmospheric oxidation to other greenhouse gases notably water vapor and CO2. If Methane release due to melting of permafrost increases, methane will accumulate in the atmosphere faster than it is converted to CO2 and therefore atmospheric concentration of methane will increase. It is estimated that if 10% of methane stored in permafrost was released, 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 with 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 of 230 years.

Has methane gas been linked to past catastrophic events or climate change?

Increased atmospheric concentration of methane has been linked to environmental changes during the Paleocene-Eocene Thermal Maximum (PETM) approximately 55.5 million years ago . Temperatures increased by 5oC during the PETM which caused extensive melting of arctic ice. The increase in temperatures and the acidification of the ocean that occurred during the PETM have led scientists to assume that Carbon release was associated with the event, with the most likely candidates being CO2 and CH4 (methane). According to Carozza et al, “more than a single source of carbon is required to explain the PETM onset ”.

Methane is also believed to have been involved in a mass extinction event during the end of the Triassic period, 199 million years ago, according to research by Micha Ruhl et al. The outcome of this event was the extinction of half of the life forms known to have existed at that time. Initially, it was assumed that widespread volcanic eruptions that were occurring during that period caused the Earth to warm up and lead to mass extinction. The study of Micha Ruhl et al. suggests that the initial warming caused by the eruptions triggered a positive feedback by causing underwater permafrost to melt and release methane gas to the atmosphere which amplified the warming even more. As a result more methane was released from further melting and caused further warming until conditions became inhospitable and eventually led to mass extinction .

How is methane hydrate dealt with nowadays in scope of climate change?

Although scientist are alarmed by recorded incidents of methane leakage from methane gas hydrates and by recorded increases in the atmospheric concentration of methane, the majority admits that more data and further investigation is required before assessing how potentially dangerous this might be. However, if the vastness of the methane deposits in naturally occurring methane hydrates is considered, as well as the fact that only a small fraction of available methane is needed to be released in order to trigger abrupt warming caused by a positive feedback effect, it follows that this should be carefully considered in proposed warming scenarios and climate models.

At present, this is definitely not the case. The Intergovernmental Panel on Climate Change (IPCC) that operates under the United Nations (UN) is assigned to review scientific evidence and make predictions on future climate change as well as assessments on its socioeconomic impact. Feedback effects, such as the release of methane from gas hydrates, are ignored in current IPCC scenarios and are completely absent from any existing models that the IPCC uses to predict future climate change. The IPCC has therefore received significant criticism from members of the scientific community which characterize their future projections for global warming as ‘conservative’ .

How widespread is really methane release from terrestrial and underwater permafrost?

Scientific research has shown that the release of methane is far more widespread relevant to the attention it is currently being given. This has been proven by extensive research on methane hydrates in the East Siberian Shelf undertaken by Natalia Shakhova. In a study published in 2008 she writes:

“Methane release from continental margins is widespread and contributes methane to
the biosphere, hydrosphere, and atmosphere, thus making up an important part of
the global carbon cycle. The contribution of arctic shallow seabed sediments to the
global carbon budget and, particularly, to the marine methane budget, has received
little attention because the area of these sediments is small in extent and because,
due to low temperatures that characterize these sediments, they are not considered
conducive to methanogenesis. In addition, in the case of the East Siberian Shelf (ESS),
shallow sediments have not been considered a methane source to the hydrosphere
or atmosphere because seabed permafrost (defined as sediments with a 2-year mean
temperature below 0°C), which is considered to underlay most of the ESS, acts as
an impermeable lid, preventing methane escape. However, our recent data showed
extreme methane supersaturation of surface water, implying high sea-to-air fluxes. .”

Shakhova’s research has shown that methane hydrates in the East Siberia Shelf are highly destabilized. She concludes that:

 “Further immobilization of stored methane could cause abrupt methane release and unpredictable climatic  consequences.”

Shakhova has made similar observations in earlier research on the East Siberian Shelf methane hydrates. Quoting from a study published in 2006:

“A hypothesized climate-change-driven increase in methane emission from the Arctic Ocean could dramatically alter not only the regional budget, but also the global cycle .”

Based on Shakhova’s conclusions, it is obvious that there is an increased probability of large quantities of methane gas to be released from methane hydrates. As discussed previously, a large atmospheric concentration of methane may have catastrophic consequences. Therefore, if we apply a risk based approach, that is Risk = Probability x Magnitude, we can infer that there is great risk involved in the current processes that methane hydrates, particularly in the East Siberian Shelf, are undergoing. Therefore, it is a global emergency that this matter is considered and taken into account in climate policy planning.

Is it possible to use naturally occurring methane hydrate as an energy source? Is this already happening?
Methane gas that exists in natural hydrates can be used as fuel upon extraction. It can either be used directly, as pure methane, or converted to methanol and other synthetic fuels. As we approach - if we have not already done so - the peaking of global oil production, methane hydrate will naturally be seen as a very attractive, untapped energy source, “especially when it occurs relatively close to the Earth’s or seabed surface ”. A Literature review of online and offline sources reveals some interesting facts on Research and Development activities of various countries on methane hydrate as a fuel source:
“In certain parts of the world characterized by unique economic and/or political motivations, gas hydrate may become a critical sustainable source of natural gas within the foreseeable future, possibly in the next five to ten years ”.

“In 1997, the U.S. Department of Energy (DOE) initiated a research program that would ultimately allow commercial production of methane from gas hydrate deposits by 2015. Three years later, Congress authorized funding through the Methane Hydrate Research and Development Act of 2000. The Inter-agency Coordination Committee (ICC), a coalition of six government agencies, has been advancing research on several fronts. Much of what we know about the basic science of methane hydrate -- how it forms, where it forms and what role it plays, both in seafloor stabilization and global warming -- has come from the ICC's research ”.

“Off the coast of Japan, the first offshore well to test the potential of methane hydrates in the seafloor was drilled in 1999. A second round of drilling here took place in 2003. Japan may be the first country to produce methane from hydrates on a commercial basis. But the head of DOE’s hydrate program has said that the US is determined to be the first to mine them ”.

Is methane gas extraction from methane hydrates a wise thing to do?

There are many dangers associated with methane extraction from gas hydrates. “Some scientists fear that drilling could destabilize hydrate deposits, triggering major submarine landslides. Around 7,000 years ago, unstable gas hydrates caused a huge landslide off Norway that produced a tidal wave that swamped much of the Shetlands […]. Additionally, there are concerns that a vast new source of fossil fuels will only serve to delay the adoption of more climate-friendly renewable energy technologies ”.

Conclusion: Tipping points in the Earth’s Climate

The fact that methane is a potent greenhouse gas and that it exists in enormous quantities under the protective shield of terrestrial and underwater permafrost are both scientifically valid and beyond any doubt. Uncertainties do exist as to the involvement of methane in past catastrophic and climate change events but much evidence is in place to suggest that it has played a role in such events and that it may do again. Furthermore more evidence is accumulating which is showing that methane from melting permafrost due to global warming, is escaping to the atmosphere and that atmospheric concentration of methane has increased in hotspot areas such as Siberia . The magnitude of harm that may follow a sudden methane release may very well be nothing less than catastrophic with major consequences to the environment and the well-being of societies, particularly in regions that are most vulnerable.

The magnitude of harm that may follow a sudden methane release may very well be nothing less than catastrophic with major consequences to the environment and the well-being of societies, particularly in regions that are most vulnerable. The 1992 UN climate change convention invokes the precautionary principle that measures are to be taken to prevent dangerous levels of atmospheric GHGs accumulating in the atmosphere; even the science is not conclusive. Extreme precaution is required to prevent increasing atmospheric methane concentrations from gas hydrates.

Therefore the exclusion of positive feedback effects associated with methane hydrate from climate models and future projections for climate change by the world’s leading organization for climate monitoring , the IPCC, is inexcusable.

Tipping Point theory provides a very strong argument for the need to consider the catastrophic potential of methane, were it to be unleashed from naturally occurring methane hydrates. The term was introduced by Malcolm Gladwell in a sociological concept to describe how little causes can have enormous and unpredictable effects . Such a tipping point is very likely to have existed in the Triassic mass extinction event, for example, where a small temperature increase caused by volcanic eruptions escalated to further increase in a non-linear fashion by way of positive feedback triggered by methane release from melting methane hydrates and which eventually led to the wiping out of 50% of known life existing at the time. A characteristic of tipping points is sudden and abrupt change once the threshold is passed. What seems negligent and insufficient to cause an enormous change may only appear so before the tipping point is reached. Thereon, change will occur abruptly and non-linearly.

Clearly global climate change risk assessment demands the inclusion of methane hydrates. Risk = Probability x Magnitude. The possible magnitude of Arctic methane destabilization by global warming (regional ocean warming) is enormous and therefore so is the risk. In conclusion the current situation of Arctic methane hydrate instability is a dire planetary emergency for all populations and all future generations.

End notes:

“Natural Gas Hydrate in Oceanic and Permafrost Environments”, Edited by Michael D. Max, Kluwer Academic Publishers, 2003
“Methane Hydrate: Little Known Energy Resource of the Future”, Kaushik Nath, 2007
“Natural Gas Hydrate in Oceanic and Permafrost Environments”, Edited by Michael D. Max, Kluwer Academic Publishers, 2003
“A sleeping giant?” Nature Reports Climate Change Published online: 5 March 2009
“Natural Gas Hydrate in Oceanic and Permafrost Environments”, Edited by Michael D. Max, Kluwer Academic Publishers, 2003
“Methane hydrate stability and anthropogenic climate change”, D. Archer, University of Chicago, Department of the Geophysical Sciences, USA, 2007
“Methane and environmental change during the Paleocene‐Eocene thermal maximum (PETM): Modeling the PETM onset as a two‐stage event”, Carozza et al, 2011
“Anomalies of methane in the atmosphere over the East Siberian shelf: Is there any sign of methane leakage from shallow shelf hydrates?”, N. Shakhova et al, 2008
“Anomalies of methane in the atmosphere over the East Siberian shelf: Is there any sign of methane leakage from shallow shelf hydrates?”, N. Shakhova et al, 2008
“Methane release and coastal environment in the East Siberian Arctic shelf”, Shakhova and Semiletov, 2006
“Natural Gas Hydrate in Oceanic and Permafrost Environments”, Edited by Michael D. Max, Kluwer Academic Publishers, 2003
“Natural Gas Hydrate in Oceanic and Permafrost Environments”, Edited by Michael D. Max, Kluwer Academic Publishers, 2003,1518,547976,00.html
“The Tipping Point – How Little Things Can Make a Big Difference ”, Malcolm Gladwell, 2000