According to a new study published in the journal Nature, increasing ocean temperatures combined with changes in the structure of the Gulf Stream are causing the rapid destabilization of large amounts of methane off the US East Coast. What the study shows is that the Gulf Stream is getting warmer due to human-caused global warming and that the warmth is pushing deeper and deeper into the ocean. As the warmer waters encounter the Continental Shelf they begin to affect massive frozen reserves of methane called methane hydrates or clathrates on the sea bed.
Clathrates are a frozen combination of methane and water. The substance is very unstable and, once disturbed, can rapidly transition from its frozen state to methane gas. Hundreds of gigatons of methane lie trapped in clathrate in the region affected by the Gulf Stream. If even a fraction of these clathrates were to destabilize, it could result in a powerful amplifying feedback to global warming, ocean and atmospheric anoxia (oxygen loss) and worse.
The study postulates that ocean warming of 5 degrees Celsius may have caused a massive release of methane about 50 million years ago resulting in a large release of methane that caused both wide-spread ocean acidification and a major increase of about 5-7 degrees Celsius in world temperatures. The sea bed in the region in question is shown to have warmed by about 8 degrees Celsius since the last ice age with rapid warming occurring since the advent of human greenhouse gas emissions.
The study found than an area of 10,000 square kilometers off the East Coast showed rapidly destabilizing clathrates. The total volume at immediate risk of destabilization was 2.5 gigatons. Because methane is many times as potent as carbon dioxide, a single release of methane of the size estimated would triple or quadruple the amount of heat forcing produced by human greenhouse gas emissions in one year. Futhermore, this study focused only on the US East Coast as a potential methane source. Other studies have found large methane releases coming from the Alaskan Continental Shelf, the East Siberian Arctic Shelf, and other regions of the Arctic. This was the first major mid-latitude study and it is also likely that vulnerable methane deposits exist in other continental shelf zones around the world.
In total, the East Coast methane store of about 300-500 gigatons of methane clathrate adds to another 1000-1400 gigatons of Arctic clathrate, 1000+ gigatons of methane stored in permafrost and at least 100 gigatons of methane stored beneath Antarctica. This total contains more carbon than all the world’s remaining conventional fossil fuels and has a very large potential to greatly enhance human-caused warming. Furthermore, unknown amounts of methane hydrate lie in wait in other world ocean regions.
Continued human CO2 emission creates an added forcing that is likely to increase the risk of a large methane release from frozen permafrost and from clathrates. It has been hypothesized that large releases of this kind caused a major temperature spike and mass extinction in the ocean about 50 million years ago. A larger release of methane about 250 million years ago called the Permian extinction event is thought to have caused a major die off of 96 percent of ocean species.
Russian Arctic researcher Shakhova has estimated that it is possible for as much as 50 gigatons of Arctic methane to be released in single large events called pulses. Such large events, if they were to occur, would have terrible regional, local, global and oceanic impacts. Large regions of the ocean would be stripped of oxygen. The local atmosphere, as well, would be at risk of becoming anoxic. Areas where atmospheric concentration of methane exceeded 5% (5000 ppm) would be at risk of severe firestorms.
But even a more gradual release of the methane would be devastating, causing an amplifying feedback to human CO2 emission that could raise world temperatures by as much as 18 degrees Fahrenheit by the end of this century. The difference between Shakhova’s large pulse and the more gradual release expected by other scientists is the difference between a flash fire or a slow bake. But the end result is the same — a world that really isn’t livable for human beings or for many other creatures either.
The Recent changes to the Gulf Stream causing widespread gas hydrate destabilization study shows that the Arctic Ocean is no longer the only region of concern for rapid methane release due to human climate forcings. Now, the Eastern Continental Shelf of the United States is shown to contain a substantial methane reserve and that 2.5 gigatons of this methane is undergoing rapid destabilization. And all of these studies, when taken into context show that continued human greenhouse gas emission is a severe and unconscionable risk. Each year, as more of these gasses enter the atmosphere, there is more and more risk of a catastrophic methane release event. Each year, as the heat builds up, we are at greater risk of entering an age when the heat content of the atmosphere is so great that large methane releases continue to occur for centuries and may result in a world that is devastated and unlivable for humans.
So for each year that we continue to emit CO2 we continue to play a game of Russian Roulette with the largest weapon on the planet — the Clathrate Gun. We know the bullet is in the chamber. We have found evidence for it in the Arctic, the Antarctic and now just off the US East Coast. But we don’t quite know whether this year’s trigger pull of another 30+ gigatons of human CO2 emission will spark a series of unstoppable and terrible events. Or if it will be next year. Or the year after.
Only one thing is certain. If we pull the trigger enough, that terrible gun is bound to go off. The best course of action is to stop pulling the CO2 trigger. To put the gun down and step away from the burning of fossil fuels which have become so very dangerous.
Links:
http://www.nature.com/nature/journal/v490/n7421/full/nature11528.html?WT.ec_id=NATURE-20121025
http://en.wikipedia.org/wiki/Clathrate_gun_hypothesis
http://www.skepticalscience.com/Wakening_the_Kraken.html
robertscribbler 
Gail Griffith
/ August 28, 2014Ocean acidification depends on menthanophils to oxidize methane. Is there evidence of widespread methanophil activity?
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robertscribbler
/ August 28, 2014The methane oxidizes in the presence of oxygen in water and breaks down into CO2. This process leeches oxygen from the water column and enhances acidification. Microbes can oxidize methane in anaerobic environments, but that’s not what the article specifically references. So the question is a bit of a red herring.
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