Earth's Climate Changes in Tune with Eccentric Orbital Rhythms

Scientific American.com ^ | December 22, 2006 | By David Biello

[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.

[Robert A Cook PE]

Darn

Somebody else wrote it down first.


Can I still claim to have thought of it first?

OK, now Death Valley is a little too far from the sea (got to be practical, ya) but the Salton Sea and Imperial Valley is low, and closer to the Gulf of California.

So, we import salt water from Mexico to the (new) salt flats instead of importing poor Mexicans, and then sell the power (a little bit) and evaporated salts for a prophet. And I fortell that CA will not want to do this ...)

[Robert A Cook PE]

Crash ice-filled comets into Mars. Sounds good. If we can steer comets into Mars then we should be able to steer them away from earth when need be,

(Crash them into Iran first to test the theory of bringing civilization to desert environments?)

[NicknamedBob]

No purpose to be served wasting icy comets on Iran.

Besides, the people of Iran are not our targets. What we need are those smart bees the Israelis are developing.

"May the fleas of a thousand camels infest your beard" takes on a new and personal menace when you consider that possibility.

The tricky part is collecting the specific DNA for targeting, and developing the targeting sensors.

We should open up Upper Class Sperm Donor Banks in Iran. Give them a hand with their suicidal tendencies, so to speak.

[patton]

Merry Christmas, my friends. Lol. the food is smelling good.

[Robert A Cook PE]

Well, you can't send mosquitos to a mid-desert landing site. ....

Well, for one generation I guess. Second generation might find it a bit dry though.

Now, abnout that box of ten billion no-see-ums imported from Alaska and Saschewannanananinainananann (never could tell when that province ended actually) into the Iran uclear test site.....

What will bee will bee,

[RightWhale]

The moon needs women ice comets.

[NicknamedBob]

"The moon needs women ice comets."

Why?

[RightWhale]

Oh, don't ask why. Just send icy comets and repeal the Treaty.

[NicknamedBob]

No problem. I still haven't figured out how to soft-land them, though.

And if it were up to me, the treaty would be as gone as the Soviet Union, START, and Krushchev's shoeshine.

[Robert A Cook PE]

Send women.

Let the comets will follow naturally?

(Are is that "Men are from Mars, Women come Mons de Venus.")

[NicknamedBob]

Comets don't follow women.

In fact, Comet and Cupid lead the pack, if I recall correctly. Of course, if you're Blitzen, the view never changes.

And you sound like you're blitzin'. Sampling the Christmas punch?


We need women on Mars. On the Moon, we need robots.

[cogitator]

Do these scientists have any reason to assume a constant rate of sedimentary addition for millions of years?

Magneto-stratigraphy defines the age boundaries for the sediments being studied.

[cogitator]

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.

Atmospheric methane oxidizes to CO2. Google phrase: "Paleocene-Eocene Thermal Maximum" (PETM for short)

[cogitator]

Diatomaceous earth is silica (chalk); made out of diatoms. This article is about calcium carbonate sediments composed primarily of foraminifera.

[cogitator]

As CH4, it doesn't really decompose into anything.

See post 93. CH4 does convert to CO2 over time (decades) in the atmosphere. Summarized grabbed from Wikipedia:

"This is the case for methane. It is oxidized by reaction with naturally occurring hydroxyl radical, OH· and degraded to CO2 and water vapor at the end of a chain of reactions (the contribution of the CO2 from the oxidation of methane is not included in the methane GWP)." GWP = global warming potential

[cogitator]

Something else caused global climate change in the past.

Lots of things cause climate to change. Name your process.

[cogitator]

ALL THE MODELS I have seen about climate shows we are due for a mini if not maxi ice age.

A recent paper in Nature predicts that the current interglacial (this one) will last another 50,000 years. All three of the Milankovitch cycles have to superimpose negatively to cause an epochal hinge point.

Google the phrase "exceptionally long interglacial" -- I'm not sure which links will be accessible, so keep clicking.

[Robert A Cook PE]

Good info and updates to all. Thank you, and Merry Christmas this New Year.

[SunkenCiv]

The Real Inconvenient Truth About Global Warming: Skeptics Have Valid Arguments
Capitalism Magazine | December 19, 2006 | Tom DeWeese
Posted on 12/20/2006 10:46:46 PM EST by ancient_geezer
http://www.freerepublic.com/focus/f-news/1756621/posts

[SunkenCiv]

Note: this topic is from December 22, 2006.

Heiko Pälike, a geologist at the National Oceanography Center in Southampton, England... 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.

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