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.
Why don't you just install a pipe from the med to the dead sea, and see how much that changes the weather?
Or dam the straits of Gibraltar, or rebuild Lake Chad?
Or bridge the Aleutian Strait, or build a tunnel under the Atlantic?
Basically because my interest is in space, and human exploration and colonization of it.
If you build a bridge over the Alutian Straits, I an't driving on it. Two different tectonic plates - sooner or later, it will fall down.
"that energy budget"
So, global climate needs a credit card now? Stupid garbage.
Just park your car in Southern California.
Sooner or later, you'll get to the Aleutian trench, and you won't need to use the bridge.
"Would the ice-dropped-upon desert residers complain?"
Hopefully, no. Explosive charges would be detonated at selected altitudes to bring the irrigation delivery to its destination as rain. Additionally, since the delivery is a requested one, persons who could perhaps be injured will have an opportunity to clear the area.
If they get hit with a bit of de-orbiting junk, it's on their own heads.
Not sure about the copper. It might be safer to use aluminum foil. We would have a period of time for testing and developing the proper techniques.
(It's a great fire-fighting possibility too. Australia would benefit enormously.)
You are going to need MUCH bigger capacitors than any I have seen.
The area is composed of sand dunes and salt lakes in a tear drop shaped formation with the point of the in a tear drop shaped formation with the point of the drop facing east and the broad deep area at the south west end. The large size of the Quattra Depression and the fact that it falls to a depth of 132 m below mean sea level has led to several proposals to create a massive hydro-electric project in northern Egypt rivaling the Aswan High Dam. The proposals all call for a large channel or tunnel being excavated from the Quattra due north about 80 km to the Mediterranean Sea. Water would flow from the channel into a series of hydro-electric penstocks which would release the water at 90 m below sea level. Because the Quattra is in a very hot dry region with very little cloud cover the water released at the 90 m level would spread out from the release point across the basin until evaporating from solar influx. Because the depression is so deep and broad, a great deal of water would be let in to maintain the artificial salt sea at the 90 m level and as the water evaporates more sea water would be sent through the penstocks to generate more electricity.
Keppler's Fault.
We use a helium tunnel at the range.
Deniers and heretics. /sarc
At the required level of activity to pay for the investment, I wouldn't want to bother with helium. I'm thinking maybe a cap of ice, and just evacuate the tunnel as much as practical, then brute-force everything else until you can get an effective launch.
Start with the Australian Outback. Set up some locations for irrigation, and deliver the water on a regular schedule.
Then move further, the Gobi and Sahara. The Sahara is three and a half million square miles of desert. It was once a breadbasket, and it could be again.
After these things have been set up and proved effective, (and paid for the cost of the infrastructure), move on to launching spaceships into orbit, or if decided on by that stage, ice loads to Mars.
One purpose in sending ice to Mars is to deflate the argument that this new source of irrigation water will cause an ocean level rise.
More atmosphere and water for Mars could be found among the gas giants and the comets, but first we'd have to launch huge ships to go after it. We could do that too.
Terraforming Earth and Mars will require incredible effort. This plan at least gives a means of paying for it.
Al Gore talks about possible problems from global warming. I propose we do something about it.
BTW, is is very considerate of you to fix our typo's in your replies. Thanks!
A launch facility not dependent on enormous quantities of rocket fuel.
A means of recovering investment costs, (irrigation).
Terraforming of two worlds.
Eventual recovery and utilization of an entire continent.
A massive presence in space, affording the opportunity to do remarkable things, including protecting the planet from errant asteroids.
Well, the biggest problem you have is that the poles are the worst places to launch - no angular velosity.
That's true, but a singular advantage that they offer is the 24 hour rotation that brings all destinations into range.
You can send ships to Mars, Venus, or into orbit around Earth or the moon.
It just depends on how much ooomph you put into the shove. We would undoubtedly need a few nuclear reactors.
Another place those reactors would be useful is in orbit. With plentiful ice available for reaction fuel, a nuclear rocket engine could move easily throughout the solar system.
We could have thousands of ships up there within the first decade of operation. They could bring over the asteroid we want to use as an anchor for the "beanstalk."
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