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  (Source: Travelvivi)
But scientists say it did not contribute to global warming today

Lawrence Livermore National Laboratory (LLNL) scientist, along with his team, recently used radiocarbon dating to trace carbon dioxide released to the atmosphere from the deep ocean at the end of the last ice age.

Radiocarbon dating employs the use of radioisotope carbon-14 to figure out the age of ancient and prehistoric carbonaceous materials. This process can be used on materials as old as 62,000 years old. 

Tom Guilderson, a scientist at the LLNL's Center for Accelerator Mass Spectrometry and an author of the study, found that an increase in atmospheric CO2 concentrations corresponded with a decreased amount of carbon-14 relative to carbon-12 in the atmosphere. 

"This suggests that there was a release of very 'old' or low 14/12CO2 from the deep ocean to the atmosphere during the end of the last ice age," said Guilderson. He noted that CO2 release may increase the rate at which ice melts after an ice age. 

Ocean circulation regulates radiocarbon in the atmosphere, and in turn, this regulates the sequestration of carbon dioxide in the deep ocean by atmosphere-ocean carbon exchange. Around 110,000 to 10,000 years ago when the last ice age occurred, lower atmospheric carbon dioxide levels coincided with increased atmospheric radiocarbon concentrations, which have been "credited to great storage of CO2 in a poorly ventilated abyssal ocean." The circulation of the ocean was drastically different back then, and Guilderson admits that he and his team do not fully understand the manner in which carbon was stored in deep ocean at that time. 

The team dated two sediment cores from the subtropic South Pacific near New Zealand and the sub-Antarctic to be approximately 13,000 and 19,000 years old. Guilderson was able to determine when the large CO2 release occurred using the carbon-14 in the cores. Also, he was able to determine the ocean pathway by which it escaped. 

"In this case, the absence of a signal is telling us something important," said Guilderson. "Deeper waters substantially depleted in carbon-14 were drawn to the upper layers and this is the main source of the CO2 during deglaciation. Data suggests that the upwelling of this water occurred in the Southern Ocean, near Antarctica. In our cores off New Zealand, which lie in the path of waters which 'turn over' in the Southern Ocean, we don't find anomalously low carbon-14/12 ratios.

"This implies that either water which upwelled in the Southern Ocean, after 16,500 years ago, had a vigorous exchange with the atmosphere, allowing its 14C-clock to be reset, or the circulation was significantly different than what the current paradigm is. If the paradigm is wrong, then during the glacial and deglaciation, the North Pacific is much more important than we give it credit for."

This carbon dioxide release sped up the melting, but when asked about CO2's contribution to

global warming today, Guilderson said this release of CO2 from the last ice age "is not relevant." But he did mention that he has used radiocarbon dating on CO2 in the atmosphere today, and that isotopic signature shows that use of fossil fuels is what is causing global warming. 

The study was published in the August 26 edition of Nature



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RE: Slow news day
By PaterPelligrino on 9/2/2010 12:22:08 PM , Rating: 2
Let me see if I follow you here.

You're saying that conservatives like yourself, who claim that AGW was thought up by the left "to ban Capitalism outright in Rich Western countries", are "hyper-informed", while your liberal opponents don't share your grasp of the issues.

Then in the 2nd sentence you state that because liberals are confident of the correctness of their position, and certain that they'll prevail in the end, they openly admit what they're after, and therefore it's easy to figure out what they want - which is, as you previously stated, the "outright banning of capitalism in the rich West".

Have I got that right?

Odd, though, that I've never heard an AGW proponent admit to wanting to ban capitalism in the West, let alone brag about it, but let's not quibble about details.

All in all, a very convincing argument you have there. I feel I should apologize. I clearly did you a disservice when I lumped you in with all those other conservatives who distort and misrepresent your opponents' positions.

It's not often that one encounters a guy with such an "acute understanding of human nature". Hats off to you bro.


RE: Slow news day
By Ammohunt on 9/2/2010 2:16:44 PM , Rating: 2
Reading comprehension not one of your strong points I see. Sorry i don’t have the patience to day to dumb it all down for you rest assured it will all come clear to you eventually.


RE: Slow news day
By PaterPelligrino on 9/2/2010 3:41:17 PM , Rating: 2
quote:
rest assured it will all come clear to you eventually.


I wouldn't count on it Ammohunt; after all, not everyone possesses your "hyper-informed" knowledge of the issues, and "acute understanding of human nature".


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