Scientists find evolution of life

EurekAlert ^ | 10/30/03

[Dales]

LIVERMORE, Calif. -- A trio of scientists including a researcher from the Lawrence Livermore National Laboratory has found that humans may owe the relatively mild climate in which their ancestors evolved to tiny marine organisms with shells and skeletons made out of calcium carbonate.

In a paper titled "Carbonate Deposition, Climate Stability and Neoproterozoic Ice Ages" in the Oct. 31 edition of Science, UC Riverside researchers Andy Ridgwell and Martin Kennedy along with LLNL climate scientist Ken Caldeira, discovered that the increased stability in modern climate may be due in part to the evolution of marine plankton living in the open ocean with shells and skeletal material made out of calcium carbonate. They conclude that these marine organisms helped prevent the ice ages of the past few hundred thousand years from turning into a severe global deep freeze.

"The most recent ice ages were mild enough to allow and possibly even promote the evolution of modern humans," Caldeira said. "Without these tiny marine organisms, the ice sheets may have grown to cover the earth, like in the snowball glaciations of the ancient past, and our ancestors might not have survived."

The researchers used a computer model describing the ocean, atmosphere and land surface to look at how atmospheric carbon dioxide would change as a result of glacier growth. They found that, in the distant past, as glaciers started to grow, the oceans would suck the greenhouse gas -- carbon dioxide out of the atmosphere -- making the Earth colder, promoting an even deeper ice age. When marine plankton with carbonate shells and skeletons are added to the model, ocean chemistry is buffered and glacial growth does not cause the ocean to absorb large amounts of carbon dioxide from the atmosphere.

But in Precambrian times (which lasted up until 544 million years ago), marine organisms in the open ocean did not produce carbonate skeletons -- and ancient rocks from the end of the Precambrian geological age indicate that huge glaciers deposited layers of crushed rock debris thousands of meters thick near the equator. If the land was frozen near the equator, then most of the surface of the planet was likely covered in ice, making Earth look like a giant snowball, the researchers said.

Around 200 million years ago, calcium carbonate organisms became critical to helping prevent the earth from freezing over. When the organisms die, their carbonate shells and skeletons settle to the ocean floor, where some dissolve and some are buried in sediments. These deposits help regulate the chemistry of the ocean and the amount of carbon dioxide in the atmosphere. However, in a related study published in Nature on Sept. 25, 2003, Caldeira and LLNL physicist Michael Wickett found that unrestrained release of fossil-fuel carbon dioxide to the atmosphere could threaten extinction for these climate-stabilizing marine organisms.

[jennyp]

Here's a frozen lake. What are these people doing, and why?

[RadioAstronomer]

Welcome back :-)

[f.Christian]

The Bible does say we will not be tempted above our rank - ability ... if you do see truth - love you will see power and evil --- the righteous will run to one and flee - eschew the other !

[jennyp]

Particularly when there's a powerful heater at the bottom of the lake.

Totally false! The snow on the surface would quench any heat coming from the core! <whoa, must be channeling someone... feeling lightheaded... must go eat dinner...>

[Alamo-Girl]

Sorry, but I cannot resist this! Your chart at post 88 mentions the 3.5 billion year dating which you and Nebullis and I were discussing on a previous thread. This are evidently the Schopf cyanobacterium-like pre-Cambrian fossils.

Lurkers might be interested in knowing that there is a dispute about the fossils:

Ancient Fossils or Just Plain Rock

And that dispute will be a subject of a seminar scheduled for November:

First Announcement: The Hunt for Precambrian Life: An Integrated Approach

[Doctor Stochastic]

I should point out that increasing the amount of heat energy in the atmosphere and oceans may not lead to just global heating. One could have more evaporation and snowfall leading to hotter tropics and ice covered poles. The average temperature may be hotter but the extremes more pronounced than at present. Current climate models don't predict things in this detail. Or one could have desert conditios around the equator and warm poles (this is the press's view.) Or the first scenario could lead to a higher albedo (ice and snow reflect more heat than land) and thus trigger a cooling effect. About all that is known is that more carbon dioxide and more methane in the atmosphere will lead to more solar energy deposit; what happens after that isn't so clear. (My guess is just longer summers and more violent storms.)

[JethroHathAWay]

That little christian wont play

knock knock

[Semper]

The Bible does say we will not be tempted above our rank - ability

And is this ability not "evolving" as we experience life - both individually and as a civilization?

[Doctor Stochastic]

Snowcone Earth?

[VadeRetro]

Indeed, the article is from January, 2000. Dispute over Schopf's claim of 3.5 giga-year-old cyanobacterial look-alikes dates from after that, maybe a year ago.

[f.Christian]

Evil is evolving !

[general_re]

About all that is known is that more carbon dioxide and more methane in the atmosphere will lead to more solar energy deposit; what happens after that isn't so clear.

Those chaos theorists ruined everything... ;)

[AndrewC]

Welcome back :-)

Well thank you very much for the welcome, but as I said to general_re, I'm just passin' through, friend. And as I also said to him, I do mean friend ;^). God bless you.

[Alamo-Girl]

Thank you for your reply!

Indeed, I figured the Lurkers here might not have been following the previous thread and thus might not know about this upcoming seminar. I wonder how long it will be before we hear the results of it?

[Physicist]

whoa, must be channeling someone...

channeling - Devil's cable -- occult/EVO-(Ouija)-lution! // chaneg channels...Bible/ANTENNA -- creation!!1!

[Doctor Stochastic]

Buffering means having a repository of the item being buffered. So while the carbon dioxide levels swing wildly in the atmosphere, the plankton absorb excess to keep the active amount in the atmosphere more nearly steady. It's the same idea of a buffer in an acidic solution. Or a buffer in a computer I/O system. (Not the same as a buffer to polish a car.)

Calcium just exists in the crust. (Ultimate it was produced in a nova or supernova.) Calcium is very active and comines with acids such as carbonic acid to produce limestone (and marble.)

[Alamo-Girl]

Welcome back, AndrewC - for however long you'll be staying!!!

[VadeRetro]

This part in particular hurts Schopf the most:

Brasier says his examination of the specimens revealed structures "indistinguishable from graphitic mineral growths that occur alongside [the purported fossils] - they frequently branch chaotically in the same way and intergrade continuously with the shapes of inanimate matter."

I tend to only quote Schopf now on matters rather far from his Apex chert fossils.

[AndrewC]

Thanks, God bless you, Ali

[Ogmios]

Buffering placemarker