Mars with Oceans ...
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.
"2. 'Eccentric Orbital Rhythms' makes a really catchy name for a rock band..."
I think you're confusing them with the 'Electric Light Orchestra' or 'Orchestral Maneuvers in the Dark' (aka OMD, which made some VERY pretty music in the 80's.)
But you're right. What goes around comes around and we haven't had an elegantly named band in a few decades now, LOL!
Only guessing 'cause my track record over millions of years has yet to be established. ;-)
I'm rather partial to "Frankly Scarlet."
I got'cha covered, pal. I'm certified to be older than dirt.
Now that's cute! :)
Husband was listening to a band called "Hinder" the other night,. Being German, I pronounced it "Hine-Der" versus "Hin-Der." LOL!
Stupid marketing IMHO, but they got a luagh out of me. ;)
TCM aired Taxi Driver recently. In the publicity it was mentioned that DeNiro ad-libbed the famous line. A great film.
Methane is the largest component of natural gas, a large percent of our energy resources. As CH4, it doesn't really decompose into anything.
(You do need large quantities of concentrated gas to make use of it though: Diffuse little bits mixed in amidst tons of muck isn't practical to even gather, much less transport and try to use.)
Only problem I see with orbit eccentricities is that they are long-period, very slow transitions: How can you explain a sudden (few hundred year) drop in temperature when the period of change of the earth's orbit (precession for example) is a few hundred thousand years with only a very small total change in sunlight.
Something else caused global climate change in the past.
We can't address today's (possible) global climate change UNTIL we can figure out WHY it changed in the past.
(Having said that, can we recover the gasses from those entrapped methane sources naturally present in the Superdome after a chili and beer cookoff Louisiana style?)
Let's have the truth. No more political agendas. If the media would just report the facts I would make up my mind without their help. When they "report" in such as way as to try to convince me of something, I don't believe them.
Very perceptive. In truth, we can examine orbital eccentricities, Solar variations, and possibly even Galactic rotations as predictable variants, but there are also unpredictable factors which can affect global climate.
Very widely spread forest fires, vulcanism, and even uncharacterized animal or plant climax populations could have had randomizing factors at critical times in Earth's wobble-dance.
Climatological profiles and computer models can not take advatage of these possibilities, so not every excursion is explicable. Sometimes things just happen, like meteoric impacts.
There are some other things we might wonder about concerning earth's orbit. If it changes eccentricity does that affect the length of the year? What is the length of the Great Year? We see estimates from 12,000 to 26,000 years, but do we actually know based on our relatively short set of observations? Can we calculate these things accurately enough based on measurements made in the past couple centuries?
.. really great thread , I hope it goes on for hundreds of posts
( although I know a Grozny O'Donnell thread would race past one like this in mere minutes , *sigh* )
Also, doesn't the axis of the Earth tilt from somewhere between 20 degrees and 25 degrees or so? At maximum tilt, 25 degrees, the climate is more temperate. At minimum tilt, or about 20, the climate cools down dramatically.
Interesting that we are about midrange now at 23, and headed downward.
ALL THE MODELS I have seen about climate shows we are due for a mini if not maxi ice age.
Drilling rig with a nuclear power plant on top - pump steam down into the deposit thru one pipe, methane comes up out another.
Something tells me, Robert, that our friend Patton didn't read the whole question you asked.
As for mining methane hydrates, I puzzled about why a nuclear reactor -- then I realized it's two birds with one stone. The reactor coolant water gets injected into the lithosphere, and clean methane can be collected for refrigeration and exported use.
Or maybe not, I just toss out ideas, the PE's get to impliment them.
(That's why I am a scientist. LOL)
bump
Mars with oceans? How are you going to do that?
Oh, you just had to ask, didn't you?
All right. I'll be brief. (Hah!)
I want to build an electromagnetic launch facility in Antarctica, where ice-shrouded ships will be launched into orbit, perhaps with enough momentum to continue to Mars.
Two advantages accrue to this scheme: One can launch ice-only shipments to desert areas of Earth as an irrigation technique.
And secondly, this procedure does not require any rocket fuel. With nuclear engines, the ice can become a fuel in orbit, being heated into steam to act as a regular rocket.
The overall goal is to terraform Earth and Mars, providing at least double or triple the living space we have now, and feeding everyone.
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