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The Methane Thread pt. 2

Re: The Methane Thread pt. 2

Unread postby dissident » Mon 06 Nov 2017, 20:28:38

The ocean anoxia CH4 cannon is going to go off this century. Due to the area coverage of the anoxic zones and the volume of biogenic carbon cycling through them, we are looking at massive amounts of CH4 pumped from the oceans. All the attention is on the crysophere CH4. The non-cryosphere CH4 will make sure that most of the cryosphere CH4 is released.

People have no instincts about ocean biochemistry. It is a very sensitive system and the assumption that the current chemical regime will stay intact until 2100 or later is simply wrong. Now that we have direct evidence of a major error in the estimate of past ocean temperatures (on the high side), the ocean anoxia regime is guaranteed and the trends seen in observations are not to be dismissed.

The trend that will lead to a tipping point by around 2035, is the progressive shallowing of the ocean surface mixed layer together with increased O2 depletion at its base. The surface waters will still be oxic, but near subsurface waters will be anoxic and the detritus rain that today is remineralized in association with CO2 release will be remineralized with CH4 and H2S release.

https://www.sciencedaily.com/releases/2 ... 063957.htm

H2S possibly contributed as the primary agent to the largest mass extinction 251 million years ago. I am going to go out on a limb and say that it would be physically impossible for it not to have been a prime factor.

H2S is a greenhouse gas:

H2S absorption intensity

but it is not as potent as CH4. Nevertheless, a layer of H2S above the ocean surface will only hammer in the last nail into the coffin.
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Re: The Methane Thread pt. 2

Unread postby dohboi » Tue 07 Nov 2017, 16:23:53

For those, unlike dis, who are a bit shaky on the science of it all I recommend the following article by Jenny Griffin.

https://www.climateemergencyinstitute.c ... ethane.pdf

There is a really good section on the basic science of what methane hydrates are and how they are formed, and then it goes on to discuss methane hydrate stability, and what happens when hydrates melt. Note the crucial importance of bacteria.

Most of the methane that is released is expected to be broken down by
bacteria as it rises up through the ocean sediments and through the water column before it
reaches the surface of the ocean. The decomposition of methane occurs at the result of
two biological processes:
• anaerobic oxidation of methane by bacteria in the sediments of the ocean floor
• aerobic oxidation of methane by bacteria in the water column. "

In particular aerobic decomposition involves the same chemical reaction as burning methane, i.e.

CH4 + 2 O2 → CO2 + 2 H2O

The result is not good ;-

"Aerobic Oxidation: When methane is broken down aerobically by bacteria in the water
column they use oxygen to facilitate the process, producing carbon dioxide which
dissolves in the seawater. This process negatively impacts marine environment in two
ways:
1. Carbon dioxide promotes ocean acidification.
2. Aerobic oxidation of methane utilizes oxygen within the water column which could
result in the expansion of oxygen depleted zones across the ocean. Oxygen
depletion can result in mass mortalities of marine organisms – oxygen poor zones
are unable to support animals that need oxygen for survival and are thus typically
devoid of marine life.


The article then refers to rapid methane release in shallow water - i.e. the ESAS scenario.

One final quote ;-
Mass Extinction Event

Even more alarming is that if ocean acidification is left unchecked it could potentially
initiate a Great Mass Extinction Event, as there is increasing evidence pointing to high
atmospheric carbon dioxide concentrations and rapidly acidifying oceans having triggered
four of the previous five Great Mass Extinctions.
Based on geological records it can be assumed that hydrates have broken down on a
large scale numerous times in the Earth’s history, leading to extreme global warming and
massive extinctions of organisms on the sea floor and beyond.


Thanks to ger at asif for links and text
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