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CO2 plunge linked to Antarctic freeze


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Lisa Wolfe
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« on: December 04, 2011, 08:00:10 pm »

CO2 plunge linked to Antarctic freeze

Stuart Gary
ABC

Scientists have linked a dramatic fall in carbon dioxide levels in the atmosphere with the formation of the Antarctic ice cap, 34 million years ago.

The new findings, reported in the journal Science, show how closely carbon dioxide levels are linked to major climatic changes.

Dr Willem Sijp of the Climate Change Research Centre at the University of New South Wales, says their research found atmospheric CO2 levels plunged by 40 per cent over a three million year period before and during the formation of the Antarctic ice sheet.

"The new report contradicts earlier work based on rock samples from the Southern Ocean apparently showing carbon dioxide levels were climbing while Antarctica was freezing over," says Sijp.

He says the new research factored in continental drift, which changed wind and ocean currents, as well as changes in the Earth's orbit.

"Earlier temperature estimates didn't take these into account, leading to inflated numbers showing increasing levels of carbon dioxide when in reality they were actually decreasing," says Sijp.

The research examined drill core samples looking at carbon isotope ratios in algae that died and fell to the sea floor 34 million years ago.

According to Sijp, changes in Southern Ocean currents and conditions meant temperatures were different and nutrient loads lower, directly affecting the algae and changing the inferred carbon dioxide levels.

"When we re-calculated atmospheric CO2, we found Antarctica's big freeze followed a fall in carbon dioxide levels," he says.
Colder Earth

Antarctic glaciation occurred during a geologic period called the Eocene to Oligocene climate transition.

"It was a time of dramatic changes triggered during a cold orbital cycle when precession of the Earth's axis and changes in its orbit aligned to make southern hemisphere summers colder," says Sijp.

"This allowed icesheets to survive year round and gradually increase in altitude as fresh snow and ice was added. As the altitude increased, the surrounding air got colder, which further aided in cooling, creating a positive feedback loop."

"At the same time continental drift ... allowed the creation of the Antarctic circumpolar current which also had a significant cooling effect on Antarctica."

Sijp says the growth of ice sheets also increased the Earth's albeo reflecting more of the Sun's energy back into space.

"But the main driver seems to be carbon dioxide, because that dropped 40 per cent over a three million year period as the planet cooled and Antarctica's ice sheets grew."

http://www.abc.net.au/science/articles/2011/12/02/3381495.htm?site=science&topic=latest
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Lisa Wolfe
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« Reply #1 on: December 04, 2011, 08:01:06 pm »



The finding strengthens the link between CO2 levels and global temperature (Source: Joe Mastroianni/National Science Foundation)
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If nothing we do matters, then all that matters is what we do. The smallest act of kindness can be the greatest thing in the world.
Volitzer
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« Reply #2 on: May 04, 2012, 03:30:27 pm »

CO2 gets absorbed by plants, combines with water and undergoes photosynthesis which allows plant sugars to forum.

Now if you want to complain about CO that just stays in the air and is a real pollutant then fine.
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