Posted on 02/26/2003 11:23:11 AM PST by blam
Source: Woods Hole Oceanographic Institution
Date: 2003-02-26
Fossil Records Show Methane In Seafloor Sediments
Released During Periods Of Rapid Climate Warming Scientists have found new evidence indicating that during periods of rapid climate warming methane gas has been released periodically from the seafloor in intense eruptions. In a study published in the current issue of the journal Science, Kai-Uwe Hinrichs and colleagues Laura Hmelo and Sean Sylva of the Woods Hole Oceanographic Institution (WHOI) provide a direct link between methane reservoirs in coastal marine sediments and the global carbon cycle, an indicator of global warming and cooling.
Molecular fossils from methane-consuming bacteria found in sediments in the Santa Barbara Basin off California deposited during the last glacial period, (70,000 to 12,000 years ago), indicate that large quantities of methane were emitted repeatedly from the seafloor during warmer phases of the last ice age. Methane, one of the major greenhouse gases, is stored on the seafloor as an ice-like solid known as methane hydrate.
Previous evidence for such massive eruptions was based on isotopic properties of calcite shells of foraminifera, microscopic marine animals commonly called forams. Because a variety of factors could lead to very similar signals in their shells, that evidence has remained controversial.
The preserved molecular remnants found by the WHOI team result from bacteria that fed exclusively on methane and indicate that large quantities of this powerful greenhouse gas were present in coastal waters off California. The team studied samples that were deposited between 44,000 and 37,000 years ago.
"For the first time, we are able to clearly establish a connection between distinct isotopic depletions in forams and high concentrations of methane in the fossil record," Hinrichs, an assistant scientist in the Institution's Geology and Geophysics Department, says. "The large amounts of methane presumably released during one event about 44,000 years ago suggest a mechanism different from those underlying the emissions at warmer periods, i.e. slow decomposition of methane hydrate triggered by warming of bottom waters. The sudden release of these enormous quantities of methane was probably caused by landslides and melting of the methane hydrate."
Since there was already indirect evidence of methane eruptions in the Santa Barbara Basin area, Hinrichs and colleagues looked for fossil remnants of bacteria that would have flourished only under high concentrations of methane. In a 44,000-year-old sediment sample, a distinct type of biomarker representing bacterial communities that oxidize methane in the absence of oxygen provided evidence for an abrupt, catastrophic release of methane, presumably trapped as hydrate below the sea floor.
The WHOI team's data, from sediment cores taken by the Ocean Drilling Program off southern California, show that substantial quantities of methane were released at least several times during the past 60,000 years, leading to periodic fluctuations in the levels of methane in deep waters in the Santa Barbara Basin.
The researchers say increased bottom water temperatures could mobilize or release significant amounts of methane hydrate in shallow waters. According to some current estimates, there are about 10,000 billion tons of methane stored beneath the ocean and on continents. In comparison, the contribution of humans to the atmosphere's inventory of greenhouse gases by fossil-fuel burning amounts to about 200 billion tons of carbon in the form of carbon dioxide. If even a small portion of the stored methane were to escape into the atmosphere, the resulting greenhouse warming would be catastrophic.
"It was a surprise to find this sort of evidence," says Hinrichs, who was originally looking for evidence indicating mechanisms other than methane. "Although this research tells us something about the amount of methane consumed by bacteria in the ocean, it doesn't tell us anything about methane emissions into the atmosphere because neither forams nor methane biomarkers record the portion of methane that escaped out of the ocean. But one thing is for sure, our results clearly show that relatively minor environmental changes can have a major impact on sensitive coastal regions with yet unknown consequences for climate and biota."
Hinrichs plans to look for similar evidence elsewhere to determine whether this process, as a driver of climate variation, happened simultaneously at other locations around the world. This work, Hinrichs says, is just the beginning of better understanding of the role of methane in the carbon cycle and ultimately on climate on geologic time scales.
"We have a very poor understanding of the biogeochemical mechanisms that control production, destruction and accumulation of methane in sediments underlying the ocean," he notes. "We need to understand the big picture of what drives methane and the carbon cycle and the actual impact of methane emissions from hydrates on climate."
WHOI is a private, independent marine research and engineering, and higher education organization located in Falmouth, MA. Its primary mission is to understand the oceans and their interaction with the Earth as a whole, and to communicate a basic understanding of the ocean's role in the changing global environment. Established in 1930 on a recommendation from the National Academy of Sciences, the Institution is organized into five departments, five interdisciplinary institutes and a marine policy center, and conducts a joint graduate education program with the Massachusetts Institute of Technology.
Does this methane deposit and release help that theory at all?
We will probably find a way to contain and harvest it before too many years, as it contains many times more petrochemicals than all todays known reserves.
Some have theorized that huge methane hydrate bubbles rising under ships could drop them deep into the ocean, and that that is the cause of the Bermuda Triangle mysteries.
SO9
We will probably find a way to contain and harvest it before too many years, as it contains many times more petrochemicals than all todays known reserves.
The main problem appears to be that it very unstable and evaporates as it’s brought to the surface.
That really doesn’t sound like too formidable a technological obstacle.
Clive Cussler wrote a book about a bad guy doing just that, along the East Coast, to trigger Tidal Waved.
No big deal. Methane has long been transported by ship as Liquified Natural Gas (LNG). Harvest it under water under pressure, bring it up in sealed containers, let it revert to gas, cool it to liquid state again, store it on ship until you get to port.
Actually, methane, CH4, is a so-called greenhouse gas just like CO2. The difference is that methane absorbs infrared (i.e. heat) energy at a different wavelengths than CO2. CO2 absorbs around 2350 cm-1 and methane absorbs around 2900 cm-1).
That's why greenies are worried about methane. The IR absorbing properties of CO2 absorb almost all the IR radiation at those wavelengths, so adding more CO2 isn't, at least in my opinion, a major contributor to green house gasses. All the IR that can be absorbed by CO2 is being absorbed by existing CO2 levels. (That's why I'm one of the scientist skeptical of global warming. My work uses the physics behind IR absorption and I have to worry about CO2 interferring with my experiments on a dialy basis.) However, there isn't as much methane in the atmosphere, so adding methane would increase the amount of IR absorbed dramatically, which, in turn, would contribute significantly more to global warming. Same reason why greenies what to ban cattle ranching - too much CH4 from cow f@rts.
Actually, what Gold maintains is that there is large amounts of primordial methane, some of which is converted to higher molecular weight hydrocargons by geological processes--not that it is formed by bacteria.
The theory was controversial at one time, but evidence in favor of it is piling up rather steadily.
[This ping list is for the evolution -- not creationism -- side of evolution threads, and sometimes for other science topics. To be added (or dropped), let me know via freepmail.]
He believes the idea that petroleum is a residue of ancient animal and plant life is absurd. There's far too much of it at depths which simply don't make sense. Also, depleted oil wells that are left dormant for a number of years somehow seem to "refill" for no reason which the conventional theories can explain. He lampoons all the "experts" who were saying that we'd have used up all the earth's petroleum reserves by 1980 while in fact the known reserves are far larger now than they were in the 70's. Finally, and remember the man is a professor of astronomy, he points to the huge amounts of hydrocarbons that are now being detected throughout the known universe.
I think this information does have a tie in with his theories in that Methane is an organic compound the origin of which has nothing to do with earlier life forms. What seems also important is that periodic warming and cooling of the earth has been going on for eons with or without the presence much less the influence of man.
Professor Emeritus of Astronomy at Cornell University; founder and for 20 years director of Cornell Center for Radiophysics and Space Research.
Fellow, Royal Society (London)
Member, National Academy of Sciences (US)
Member, American Academy of Arts and Sciences
Member, American Philosophical Society
Fellow, American Geophysical Union
Honorary Fellow, Trinity College, Cambridge
Gold Medal, Royal Astronomical Society (UK)
Doctor of Science, Cambridge University
Honorary M.A. Harvard University
Previous employment:
John L. Wetherill Professor of Astronomy, Cornell University;
Chairman, Department of Astronomy Assistant Vice President for Research, Cornell University
Robert Wheeler Willson Professor of Applied Astronomy, Harvard University
Chief Assistant to British Astronomer Royal Lecturer in advanced physics, Cambridge University
Radar development work, British Admiralty during World War II
280 publications in various fields of science, including cosmology, mechanism of mammalian hearing, nature of pulsars as rotating neutron stars, aspects of solar system research, origin of planetary hydrocarbons. For 7 years a member of the President's Space Science Panel (US).
Invited Lectureships:
Vanuxem Lecture, Princeton University
Welch Lecture, University of Toronto
Milne Lecture, Oxford University
George Darwin Lecture, Royal Astronomical Society, London
Lindsay Lecture, National Aeronautics and Space Administration
Yup. I've seen this on one of the documentary program. In the experiment, the ship sank.
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