Skip to comments.Earth's Climate Changes in Tune with Eccentric Orbital Rhythms
Posted on 12/22/2006 11:53:58 AM PST by aculeus
The useless shells of tiny ocean animals--foraminifera--drift silently down through the depths of the equatorial Pacific Ocean, coming to rest more than three miles (five kilometers) below the surface. Slowly, over time, this coating of microscopic shells and other detritus builds up. "In the central Pacific, the sedimentation rate adds between one and two centimeters every 1,000 years," explains Heiko Pälike, a geologist at the National Oceanography Center in Southampton, England. "If you go down in the sediment one inch, you go back in time 2,500 years."
Pälike and his colleagues went considerably further than that, pulling a sediment core from the depths of the Pacific that stretched back 42 million years. Limiting their analysis to the Oligocene--a glacial time period that lasted between roughly 34 million and 23 million years ago--the researchers found that global climate responds to slight changes in the amount of sunlight hitting Earth during shifts in its orbit between elliptical and circular. "Of all the records so far, this is both the longest and, also, the clearest that most of the climatic variations between glacial and interglacial at that time [were] most likely related to orbital cycles," Pälike says.
The researchers pulled specific foraminifera samples from the core and then dissolved the shells in acid. They pumped the resultant carbon dioxide gas into a mass spectrometer and determined exactly what elements comprised the shells. This allowed them to distinguish between shells composed of the relatively lightweight isotopes of carbon and oxygen versus those made with a higher proportion of heavier isotopes.
The isotopes, in turn, reveal a picture of the climate eons ago. Oxygen (O) with an atomic weight of 16 evaporates more readily than its heavier counterpart 18O. Thus, when ice caps form, ocean water bears a higher ratio of the heavier isotope. Because the tiny creatures build their shells from materials in seawater, their calcium carbonate homes reflect the ratio of the two isotopes in the seas of that time. "They are a recorder of how much ice is present on the earth at any given time," Pälike notes.
The same is true for the various isotopes of carbon, 12C and 13C. Because plants preferentially use the lighter isotope, its scarcity is a record of how much life the oceans supported. By matching these isotope ratios to the astronomical cycle--Earth's orbit oscillates between an elliptical and circular path on a roughly 400,000-year cycle--the researchers found that patterns of glaciation and ice retreat followed the eccentricity of our planet's orbitthey report in the December 22 Science.
But the eccentricity of Earth's orbit does not cause that much of a flux in the amount of sunlight the planet receives; that energy budget is much more strongly impacted by variances in the degree ofEarth's tilt toward or away from the sun, which would lead one to expect glaciation to occur on a shorter cycle. Instead, the long times required to move carbon through the oceans apparently acts as a buffer. "Each carbon atom that you put in the ocean stays there for about 100,000 years," Pälike explains. "The climate system accentuates very long periodic variations and dampens shorter term variations."
Earth is currently nearly circular in its orbit and, if this Oligocene pattern were to be followed, would next be headed into another ice age in about 50,000 years. But the amount of carbon dioxide in the atmosphere has reached levels not seen for millions of years prior to the Oligocene. Thus, to get an accurate picture of what the climate might be like in coming years, scientists will have to continue back even farther in history to a period known as the Eocene.
It is already clear, however, that the effects of the carbon released now will affect the oceans for years to come. "Another effect of this residence time of carbon in the ocean is that it takes a long time to flush the system out," Pälike says. "It will take a very long time to go back to the level that existed before a large excursion of CO2. It's not going to be doomsday, end of the world, but a rise in sea level would affect a very large percentage of humankind." Not to mention the shells laid down today on the deep ocean floor of the Pacific.
© 1996-2006 Scientific American, Inc.
1. Out Mayor here accuses people like me who disagree with him of having Eccentric Orbital Rhythms all the time.
2. "Eccentric Orbital Rhythms" makes a really catchy name for a rock band...
An inconvenient truth.
Once again CO2 responds to earth cycles and not the other way around.
Eccentric describes Algore to a T.
How inconvenient for Algore.
On the front: MERRY CHRISTMAS
On the inside: Put out that damn Yule Log. It causes Global Warming
Source: Jay Leno
Except this sediment doesn't settle in nice neat, undisturbed layers. Ocean currents pile them up is some places, sweep them away in others, not to mention earth quakes and other catastrophic events that have happened over the centuries. There are huge deposits of methane ice off the coast of near every continent containing so much energy that it dwarfs that of all the worlds oil deposits. This stuff releases methane and co2 constantly, but for some reason it's never taken into account, nor is it's potential for alternative energy.
Methane Hydrates. Since the 1970s, methane has been discovered in ice lying on, or hundreds of feet below, the deep ocean floor off coastlines. The ice molecules form tiny cagelike structures containing one or more methane molecules. The total energy value of this methane-ice combination, called methane hydrate, may be twice that in all the worlds known coal, oil, and natural gas combined
Water will freeze at slightly warmer temperatures if it is under high pressure and contains dissolved methane. Such temperatures and pressures exist 2,000 feet or more below sea level. There, vast methane deposits are found trapped in ice on and under the deep sea floor, but primarily along coast lines. This methane is escaping into the atmosphere at a rate that would be dangerous if it continued for a million years or so. So obviously it isn't millions of years old. We'd all be dead.
The pacific floor is dished in, and the mid atlantic ridge pushes the sea floor up; it slopes from the coastlines down to a point that's deepest between the mid atlantic ridge and the coastlines. Wanna bet that sediment drifts slowly towards the deepest parts of these formations? Using core samples of this stuff as measurements of the earths age is just plain silly.
There is no way to predict how much is slides towards these centers a year or how many events have effected it, the rate at which this sediment is produced, that it was always constant, etc etc. What about so called continental drift?
Surely that moved it around a lot in 42 million years. Not to mention that we'd all be dead or very stoned from breathing all that methane gas released from the Methane Hydrate ice formations. There is no way that this stuff can be used to determine what the weather was at any point in history because of these underterminable variables.
Heiko Pälike had better head back to the guessing board if he wants to get more grant money. Surely he could have come up with something more believable than this. It can't be that hard.
If we dont oil the drive shaft once a week, Melmacs orbit will start to squeek.
And if we ever have an ocean inversion...well, hold your breath.
I think that depends on how many dinosuars are being supported on the orbital surface vs those that are turning into oil wells below the orbital plain.
Whatever you do, don't flick that bic!
Seriously, I wonder why that stuff isn't being explored as at the very least a very cheap natual gas supply? It would be better to burn it rather than it allowed to go to waste bubbling up and being released naturaly into the atmosphere.
I can only guess that it's being saved for "discovery" at a later time once big oil has extracted all they can from oil.
but doesn't that depend on the rate at which methane is removed from the atmopshere?
However...you make a good point, it is just the next energy supply, bugger all those peak oil idiots.
but doesn't that depend on the rate at which methane is removed from the atmopshere?
I really don't know. I haven't looked into this much other than reading about it once. I can only gather from this that methane is slowly building up in the atmosphere at a rate greater than the other gases to the point where it become toxic to us. Maybe our bodies will adapt and it won't bother us except when we try light up a smoke. Does it escape the atmosphere, or combine with other gasses and become something else? I thought only hydrogen was light enough to escape the earths gravity.
So.....it's not the Sun's fault ......it's the Earth's fault.......or the Solar system........or the galaxy
You mean "scientists" have only now figured out what makes "winter" in northern climates? In fact isn't today the earths max. tilt away from the sun at the north pole? (the shortest day of the year)
(I really don't buy this "shift" in the earths orbit around the sun changing from circular to elliptical and back again either. Maybe it's just the earths wobble stabliizing slowly, makes more sense.)
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