Over the last couple weeks, the climate blogosphere has been lighting up over a recent report that enormous plumes of methane are bubbling to the surface off the coast of eastern Siberia in Russia. (Original article in the Independent online.)
So, what does this mean? It's a lot of methane, to be sure. The discovery was first made in 2010 and estimated at over 7 million tons (roughly equivalent to the methane emissions from the rest of the whole ocean). Now scientists report even more methane coming up, in plumes over a kilometer wide, although they aren't estimating exactly how much more yet.
One of the researchers described the plumes in the Independent as "continuous, powerful and impressive seeping structures." I'm imagining a loose strand of gas bubbles rising up through the ocean to the surface, more like scuba diving CO2 emissions than Old Faithful. The authors use the term "ebullition" to describe the process -- a new word for me and an instant favorite.
Left unsaid in all this buzz, but nevertheless implied is the worry that human-caused global warming triggered the methane release. Buried deep under the seafloor of the Arctic Ocean is a reservoir of carbon called methane hydrates, methane gas trapped in a cage of ice. Some scientists estimate they hold more carbon than all remaining fossil fuel reserves combined.
IF these things melted and released all their methane, it would be catastrophic for climate change. Methane is more than 20 times as powerful as CO2 and a major contributor to climate change, typically from emissions from livestock and landfills. Could that be what these scientists discovered? Answer: No. Under closer examination, it turns out that although recent climate change has indeed warmed up the Arctic Ocean and a thin layer of the seafloor beneath it, it hasn't gotten anywhere close to where the methane hydrates lie buried 200 meters below the seafloor. Before human warming began, buried permafrost (permanently frozen mud) started about 25 meters below the seafloor. Now, rising sea temperatures have increased that depth to 26 meters below the seafloor. (A meter's not a lot, but it's incredible to me that our CO2 emissions have done anything at all below the floor of the Arctic Ocean -- more evidence that the effects of climate change are real and in progress.)
But let's dig a little deeper (pun intended). Where did these methane hydrates come from in the first place? Are they the source of the methane or not? And if we're not melting them, where are the methane plumes coming from?
I blogged on the mysterious methane hydrate back in April, but they're cool enough (last pun, promise) to warrant a second look. They're sensitive entities that can only exist under cold, high-pressure conditions, such as at or below the seafloor. Because they've got methane in them, you can burn them, which is why their nickname is "fire ice." The methane inside comes from ancient marine plankton that got buried over time in the mud and decomposed, eventually ending up at just the right temperature and pressure conditions to get trapped within a cage of ice.
Usually, methane hydrates exist 300-500 meters below the seafloor, but in the Arctic, where it's colder, they can exist at shallower depths, around 200 meters. This is what makes them more susceptible to warming. But the same researchers who discovered the plumes of methane calculate that even if humans keep on cranking up the Earth's thermostat for another 1000 years, we'll still only defrost the top 75 meters of seafloor, so they seem pretty safe for the time being.
But these methane hydrates aren't the only bits of methane buried beneath the ocean. The rest of the permafrost has methane trapped in it, too, even if it's not in the cool form of fire ice. And it appears to be this methane that's the source of the current ebullition.
Prior to 8000 years ago, this part of Siberia was actually land. But as sea level rose after the last ice age, the ocean flooded this part of the coast, putting the land under water, where it's been ever since. The researchers believe that the methane leaking out today is left over from the permafrost adjusting to being submerged by the ocean 8000 years ago.
If this is the case, it brings up some new questions as well: We know where the methane is NOT coming from, but aren't any closer to knowing exactly where it is coming from. What depth? (Somewhere below 26 m but above 200 m, I'm guessing.) How much is down there? Has the methane always been bubbling up in this part of the Arctic and are scientists just now discovering it? (It's a remote spot for sure and may have eluded detection as a result.) Or is this a new phenomenon and if so, what's changed?
And lastly, what does this mean for climate change? 7 million tons is about 2.5 percent of global methane emissions, making it a small, but meaningful factor to add to the mix of gases currently warming the planet. Not one that we have much control over, though. For now, it's another reminder that while we know climate change is poised to change human life forever, many of the details keep getting more complicated -- and more dire.
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http://web.mit.edu/newsoffice/2009/roulette-0519.html
PWR
Once, in the so-called MWP, and in the last 30-40 years. It simply hasn't been warm enough to melt the ice cover, the permafrost (on land) and for the heat of the sun to penetrate to the supercooled salt water that keeps such things relatively stable at depth.
In that 30-40 year span, it is really the last 20 years that becomes of issue with regard to the mass release.
I don't know any of this for a fact, but given what we know about hydrates, how they form, and what conditions they are stable under, it seems to be consistent.
As the article states, more research is necessary.
Also, while methane is a potent GHG (20 times more powerful than CO2), it is less than 1.5 ppm presently (projected to be at that number in 2100). CO2 is 391 ppm by current measurements.
Doing some crude math, we can see that while methane is significant to the GHE, it is less so than CO2 by almost 20 times. Or, methane only accounts for 0.05% of the warming observed (there are other contributors, but for the purpose of this illustration, we're only going to look at the relationship between the two).
Which means that the mathematical relationship between exogenous and 'natural' emissions cannot be completely wrong.
You don't want to light up anywhere around a methane leak.
Apart from that--
The article says that methane is "more than 20 times as powerful as CO2 and a major contributor to climate change".
Lay a large plastic cover over the leaks. Capture the methane and use it for fuel. Since the major POC's of methane are CO2 and water, we can eliminate a sizable portion of the nastier greenhouse gases by converting them to not as nasty greenhouse gases and solve the enrgy crisis at the same time.
Makes as much sense as windmills............................
1. Accord to a study sponsored by NOAA and the National Climate Data Center, there are about 1.5 trillion tons of carbon in the permafrost (http://onlinelibrary.wiley.com/doi/10.1111/j.1600-0889.2011.00527.x/full).
2. This does not include methane hydrates which are estimated to contain another 3 trillion tons of carbon (http://marine.usgs.gov/fact-sheets/gas-hydrates/title.html)
3. Over the past half-decade, we have observed methane emissions increasing from Arctic permafrost melt on land resulting in increased emissions of 30% (http://www.guardian.co.uk/environment/2010/jan/14/arctic-permafrost-methane)
4. Last year, an NSF funded study found large methane seeps measuring tens of meters across in the East Siberian Sea. The study also discovered a perforated sea bed leaking large volumes of methane and warned that the methane cap was very unstable and could dissolve, releasing large amounts of methane. http://www.nsf.gov/news/news_summ.jsp?cntn_id=116532
5. This year, we have reports from the East Siberia Sea showing huge volumes of methane, much larger than those reported last year, coming from the ocean. Though unconfirmed, these reports show a disturbing trend.
6. Methane levels in the atmosphere are increasing. http://www.esrl.noaa.gov/gmd/aggi/aggi_2011.fig2.png
7. Arctic methane release is one of the key climate feedbacks to human caused global warming.
What we are seeing is, most likely, not the apocalypse. At least not this year ;). But it is a very bad set of indicators that show the carbon sinks in the arctic turning into carbon sources. It does make the job of containing human-caused global warming that much more difficult. It also underlines the urgency and need to transition away from fossil fuel sources of energy now and not later.
Indian legend has a story of an evil smell coming ashore and killing whole villages. ?
Speculation of a large methane hydrate release creating a bubble in the ocean and causing various ship to disappear, as in the " Bermuda Triangle". The hydrate is extremely interesting that's for sure.
"Dr Semiletov's team published a study in 2010 estimating that the methane emissions from this region were in the region of 8 million tons a year but the latest expedition suggests this is a significant underestimate of the true scale of the phenomenon."
http://www.independent.co.uk/news/science/vast-methane-plumes-seen-in-arctic-ocean-as-sea-ice-retreats-6276278.html#disqus_thread
http://en.wikipedia.org/wiki/File:Methane-global-average-2006.jpg
Finally, the analysis about methane hydrates and permafrost methane is inaccurate. Methane hydrates are stable at about 200 meters below the surface water. But if ocean temperatures increase, the layer of stability goes down just as increasing ocean temperatures will destabilize methane in permafrost below 25 meters. In short, it is just as likely that the massive volumes of methane are coming from permafrost as hydrate.
That actual emissions for the area of the ESAS surveyed appear to have increased by more than 18x in a single year is indeed cause for concern. For an example of how the permafrost cover can be very much less than represented, see Figure 2 of “Modeling sub-sea permafrost in the East Siberian Arctic Shelf: the Dmitry Laptev Straitâ€.
This is available at: http://iopscience.iop.org/1748-9326/5/1/015006 .
Oh, and by the way, Shakhova estimates that 360 billion tons of methane exist in free gas form below the permafrost. Over the last five years, she has in fact been repeatedly saying that the actual emissions far exceed the estimates derived from models. In a single year, the largest plumes increased by more than 100x. When are we going to take this seriously?