Sand is not the only thing on the move in the waters off the eastern United States — a shift in the Gulf Stream is melting methane hydrate in sediments that could release methane gas.
Image: David A. Harvey/National Geographic/Getty Images
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Somewhere off the eastern coast of North Carolina, a frozen mixture of water and methane gas tucked in seabed sediments is starting to break down. Researchers blame a shifting Gulf Stream — the swift Atlantic Ocean current that flows north from the Gulf of Mexico — which is now delivering warmer waters to areas that had previously only experienced colder temperatures.
“We know methane hydrates exist here and, if warming continues, it can potentially lead to less stable sediments in this region,” says Matthew Hornbach, a marine geologist at the Southern Methodist University in Dallas, Texas, who led the study that is published online today in Nature. The results suggest that the warmer temperatures are destabilizing up to 2.5 gigatons of methane hydrate along the continental slope of the eastern United States. This region is prone to underwater landslides, which could release the methane, a powerful greenhouse gas.
Whether that methane would make it to the atmosphere and worsen global warming is unclear, but scientists think that it is unlikely. “We don’t need to worry about any huge blow of methane into the atmosphere,” says Carolyn Ruppel, a geophysicist at the US Geological Survey in Woods Hole, Massachusetts. Rather, she says, Hornbach and his co-author Benjamin Phrampus, also of the Southern Methodist University, have uncovered a powerful new way to use data from the geological record to catch non-anthropogenic climate changes that are already happening.
Frozen zone
The authors' approach combines models of subsurface temperature dynamics with seismic images to directly detect the depth at which the methane hydrate is no longer stable and shifts from a frozen solid to free gas. Because hydrate formation is dependent on temperature, the position of the bottom of this frozen zone can be used to estimate subsurface temperature dynamics.
Using seismic data collected in 1977 to model where they expected the frozen methane to become gaseous in the western North Atlantic margin, they found that the observed interface between the frozen solid and the free gas was much deeper than predicted. After systematically checking every detail, the team ruled out several factors that could have explained their observations — including sea-level changes, increased sedimentation rates or decreased heat flow through the sediments. They eventually realized that the only thing that could cause the discrepancy was that the water was cooler in the past. Phrampus ran the model again using data from much cooler waters 100 kilometers northwest of the Gulf Stream, and got an almost perfect fit.
Next, the authors modeled heat flow through the methane hydrate sediments in relation to time, and estimated that it would take around 5,000 years of warmer waters for all of the methane to sublimate and become gas. “We don’t know where we are in the 5,000-year time frame, but our best approximation suggests we are 800 to 1,000 years in,” says Phrampus.
Trouble ahead?
This work promises to reinvigorate an ongoing debate over the risk of methane release from the oceans and whether destabilized hydrates make the continental slopes more unstable.
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Add Comment"Whether that methane would make it to the atmosphere and worsen global warming is unclear, but scientists think that it is unlikely. “We don’t need to worry about any huge blow of methane into the atmosphere,” says Carolyn Ruppel, a geophysicist at the US Geological Survey in Woods Hole, Massachusetts."
Reply | Report Abuse | Link to thisMakes one wonder why this "perceived" catastrophe, is constantly being flung out in the MSM. I'm sure it won't be long before Sci-Am publishes another story, claiming the exact opposite. Alarmism can never be falsified, because there are always potential catastrophe and some of those catastrophes will happen, as they have historically from time to time.
The skeptics job is to try and sort out "The sky is falling" from the natural variations which could cause problems. This ensures resources are not miss-deployed, and are available for real emergencies, both prophylactic and direct. We need no climate "cane toads" nor "run for the hills" confusion added. GK
GK:
Reply | Report Abuse | Link to thisHave you not heard of AGW caused by an increase in CO2? The troubling part about your attitude is that you fail to acknowledge that "resources" (dollar bills) may be invested in alternative energy, an investment that has already been proven to be profitable in the current economic environment, and one that, most likely, will be the only way forward.
Karst is an AGW denialist. He cherry-picks data and quote-mines like a champion. He's irrationsl; don't pay attention to him.
Reply | Report Abuse | Link to thisYou can tell that GK gets all of his information from Fox News, because of his genius use of the term "MSM". How many more studies do we need showing that Fox News viewers are the least-informed viewers on TV? People who don't read newspapers or watch the news score higher than Fox News viewers in information tests.
Reply | Report Abuse | Link to thisThe below article lists no less than SEVEN studies showing that Fox News Viewers are one step above pet rocks when talking about knowledge of anything of importance in the news.
STUDIES:
1. http://climateshiftproject.org/wp-content/uploads/2011/11/FeldmanStudy.pdf
(this one is MSNBC vs CNN vs Fox News - guess which one is dead last...
2. http://woods.stanford.edu/docs/surveys/Global-Warming-Fox-News.pdf
3. http://www.kff.org/healthreform/upload/8148.pdf
4. http://firstread.msnbc.msn.com/_news/2009/08/19/4431138-first-thoughts-obamas-good-bad-news
5. http://www.comm.ohio-state.edu/kgarrett/MediaMosqueRumors.pdf
6. http://www.pipa.org/OnlineReports/Iraq/IraqMedia_Oct03/IraqMedia_Oct03_rpt.pdf
7. http://www.worldpublicopinion.org/pipa/pdf/dec10/Misinformation_Dec10_rpt.pdf
Queue GK talking about how all studies are made up by bad scientists - all science is wrong - and the MSM is the problem.
"Reality a well-known liberal bias!!: ~ Stephen Tyrone Colbert
Oops... "Reality has a well-known liberal bias." Sorry for messing up your quote, S Tyrone Colbert!
Reply | Report Abuse | Link to thisI haven't a clue how "FOX" enters the discussion. I retired to a farm (in the middle of nowhere) many years ago. If I had a tower antenna, I probably could pick up a signal, but it certainly wouldn't be FOX.
Reply | Report Abuse | Link to thisThere was a "fox" in my barnyard the other day, but I introduced him to my "little friend" and he is no more.
Perhaps y'all have spent too long sniffing methane (NG), in your ovens, to know sh*t from putty. GK
G.K. You are on the receiving end of programmed responses in the style of Ingsoc or DuckSpeak ( George Orwell )where political responses are set up on automatic.
Reply | Report Abuse | Link to thisThomas Paine
To argue with a person who has renounced the use of reason is like administering medicine to the dead.
Else we wouldn't have to listen to the drivel discarding scientific method in favour of Authority, which asserts AGW and claims to 'scientifically' predict the future. That's an interesting problem in experimental verification.