These criteria make their distribution fairly regular and therefore easy to find. This could be of huge importance due to the potential of methane clathrates as a huge energy source. The USGS conservatively estimates worldwide carbon bound in these formations as double the total carbon known from all fossil fuels on earth!
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| BGS diagram showing the distribution of organic carbon in Earth Reservoirs (note gas hydrates eqaute to over 50%) |
Zhang et al have this year looked in great depth at this source of hydrocarbon. 1m3 of hydrate contains the equivalent of 164m3 of methane under normal conditions! Therefore it could be a very efficient source of energy if harnessed. Due to the precise environment needed for the hydrates to form it is relatively easy and successful to predict where they occur.
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| Distribution of known methane hydrate deposits, concentrated on the continental slopes. |
However there is a great danger in doing so, as the risk of methane leaking to the atmosphere could be detrimental to global climate. Overpeck and Cole, 2006, discussed the risk of methane release, not only from accidental leakage if we were to mine them, but also from less invasive human interaction: climate change. Anthropogenic climate change results in the hydrates becoming unstable very quickly due to a warmer environment. Decomposition leads to decreased stability of the sea bed and therefore landslides, releasing huge quantities of methane into the ocean and (eventually) the atmosphere. It has ben estimated that 2000-4000 gigatonnes of carbon could be released if CO2 reaches 3x Pre-Industrial levels! This would kick-start a horrific climate feedback cycle, whereby the increased methane would keep further warming the planet, leading to further methane clathrate decay.
The possibility of this happening is all too real. It is thought that abrupt climate and ocean change at the PETM (see my colleague's blog, A Warning From the Past, for more information) was driven by methane clathrate release, and the affects lingered for 100,000 years! This led to decreased ocean pH, dissolution of seafloor carbonates and extreme global warming, resulting in the largest mass extinction Earth has ever faced!
So, by humans potentially causing methane releasing landslides from extraction and anthropogenic climate change, could we be facing a similar demise??
Currently we are not at imminent risk, even though methane is starting to become unstable and dissociate in the very Northerly latitude seas, resulting in traces of methane in the water column. In a "first of it's kind" report last year by Elliot et al, a simulation of how clathrate-derived methane is currently behaving in the oceans was made. The results of this test were surprising; currently although methane build up in the Arctic is enhanced it is not reaching the atmosphere. This is because fresh polar surface waters are working to block the escaped methane and transport it to deeper ocean. Further studies will of course have to be done to be sure of this mechanism, but it is reassuring to know that heightened methane levels are not leaking to the atmosphere yet.
As climate change continues to take a hold of our planet's processes, however, the likelihood is ocean currents shall be affected and may divert their paths or be weakened. What then, if the methane enahanced water is not dragged down to the depths? There are though to be far more methane hydrates on the continental shelves today compared to 55Ma, at the time of the PETM. I therefore worry that Earth's most powerful mass extinction is actually still yet to come.
Note: Institue log-ins may be required for the scientific papers linked to.
The possibility of this happening is all too real. It is thought that abrupt climate and ocean change at the PETM (see my colleague's blog, A Warning From the Past, for more information) was driven by methane clathrate release, and the affects lingered for 100,000 years! This led to decreased ocean pH, dissolution of seafloor carbonates and extreme global warming, resulting in the largest mass extinction Earth has ever faced!
So, by humans potentially causing methane releasing landslides from extraction and anthropogenic climate change, could we be facing a similar demise??
Currently we are not at imminent risk, even though methane is starting to become unstable and dissociate in the very Northerly latitude seas, resulting in traces of methane in the water column. In a "first of it's kind" report last year by Elliot et al, a simulation of how clathrate-derived methane is currently behaving in the oceans was made. The results of this test were surprising; currently although methane build up in the Arctic is enhanced it is not reaching the atmosphere. This is because fresh polar surface waters are working to block the escaped methane and transport it to deeper ocean. Further studies will of course have to be done to be sure of this mechanism, but it is reassuring to know that heightened methane levels are not leaking to the atmosphere yet.
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| Methane concentrations are rising fastest in the Arctic (yellow and red areas) |
As climate change continues to take a hold of our planet's processes, however, the likelihood is ocean currents shall be affected and may divert their paths or be weakened. What then, if the methane enahanced water is not dragged down to the depths? There are though to be far more methane hydrates on the continental shelves today compared to 55Ma, at the time of the PETM. I therefore worry that Earth's most powerful mass extinction is actually still yet to come.
Note: Institue log-ins may be required for the scientific papers linked to.
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