Featured Research

from universities, journals, and other organizations

Ice Age carbon mystery: Rising carbon dioxide levels not tied to Pacific Ocean, as had been suspected

Date:
October 4, 2011
Source:
University of Michigan
Summary:
After the last Ice Age peaked about 18,000 years ago, levels of atmospheric carbon dioxide rose about 30 percent. Scientists believe that the additional CO2 -- the source of which was thought to be the deep ocean -- played a key role in warming the planet and melting the continental ice sheets. But a new study suggests that the deep ocean was not an important source of carbon during glacial times. The finding will force researchers to reassess their ideas about the fundamental mechanisms that regulate atmospheric CO2 over long time scales.

Scientists sampling a deep-sea sediment core.
Credit: Image courtesy of Alan Mix

After the last ice age peaked about 18,000 years ago, levels of atmospheric carbon dioxide rose about 30 percent. Scientists believe that the additional carbon dioxide -- a heat-trapping greenhouse gas -- played a key role in warming the planet and melting the continental ice sheets. They have long hypothesized that the source of the gas was the deep ocean.

But a new study by a University of Michigan paleoclimatologist and two colleagues suggests that the deep ocean was not an important source of carbon during glacial times. The finding will force researchers to reassess their ideas about the fundamental mechanisms that regulate atmospheric carbon dioxide over long time scales.

"We're going back to the drawing board. It's certainly fair to say that we need to have some other working hypotheses at this point," said U-M paleoclimatologist David Lund, lead author of a paper in the journal Nature Geoscience.

"If we can improve our understanding of the carbon cycle in the past, we will be better positioned moving forward as CO2 levels rise due to anthropogenic causes," said Lund, an assistant professor in the U-M Department of Earth and Environmental Sciences. Lund's co-authors are Alan Mix of Oregon State University and John Southon of the University of California, Irvine.

The study, which involved radiocarbon-dating of sediments from a core collected at a deep-ocean site (water depth 8,943 feet) off the coast of southwestern Oregon, was supported by the National Science Foundation and the University of Michigan.

The work involved radiocarbon dating dozens of sediment samples that contained microscopic shells created by plankton. The samples were collected from various locations in the core, spanning the period from 8,000 to 22,000 years ago. Over thousands of years, ocean water circulates from the surface to the bottom, then back to the surface. The radiocarbon results revealed the basin's circulation or "ventilation" rate, the amount of time that had passed since the various deep-water samples were last in contact with the atmosphere.

The scientists expected to find that the ventilation rate in the basin slowed during glacial times, allowing carbon dioxide to accumulate in the abyss and depleting atmospheric levels of the gas.

Surprisingly, they found that the ventilation rate during glacial times was roughly the same as it is today, suggesting that the Pacific was not an important reservoir of carbon during glacial times.

"Frankly, we're kind of baffled by the whole thing," said Oregon State University paleo-oceanographer Alan Mix, one of the co-authors. "The North Pacific was such an obvious source for the carbon, but it just doesn't match up."

"At least we've shown where the carbon wasn't," Mix said. "Now we just have to find where it was."


Story Source:

The above story is based on materials provided by University of Michigan. Note: Materials may be edited for content and length.


Journal Reference:

  1. David C. Lund, Alan C. Mix, John Southon. Increased ventilation age of the deep northeast Pacific Ocean during the last deglaciation. Nature Geoscience, 2011; DOI: 10.1038/ngeo1272

Cite This Page:

University of Michigan. "Ice Age carbon mystery: Rising carbon dioxide levels not tied to Pacific Ocean, as had been suspected." ScienceDaily. ScienceDaily, 4 October 2011. <www.sciencedaily.com/releases/2011/10/111003180440.htm>.
University of Michigan. (2011, October 4). Ice Age carbon mystery: Rising carbon dioxide levels not tied to Pacific Ocean, as had been suspected. ScienceDaily. Retrieved April 20, 2014 from www.sciencedaily.com/releases/2011/10/111003180440.htm
University of Michigan. "Ice Age carbon mystery: Rising carbon dioxide levels not tied to Pacific Ocean, as had been suspected." ScienceDaily. www.sciencedaily.com/releases/2011/10/111003180440.htm (accessed April 20, 2014).

Share This



More Earth & Climate News

Sunday, April 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Drought Concerns May Hurt Lake Tourism

Drought Concerns May Hurt Lake Tourism

AP (Apr. 18, 2014) Operators of recreational businesses on western reservoirs worry that ongoing drought concerns will keep boaters and other visitors from flocking to the popular summer attractions. (April 18) Video provided by AP
Powered by NewsLook.com
Man Claims He Found Loch Ness Monster With... Apple Maps?

Man Claims He Found Loch Ness Monster With... Apple Maps?

Newsy (Apr. 18, 2014) Andy Dixon showed the Daily Mail a screenshot of what he believes to be the mythical beast swimming just below the lake's surface. Video provided by Newsy
Powered by NewsLook.com
First Ever 'Female Penis' Discovered In Animal Kingdom

First Ever 'Female Penis' Discovered In Animal Kingdom

Newsy (Apr. 18, 2014) Not only are these newly discovered bugs' sex organs reversed, but they also mate for up to 70 hours. Video provided by Newsy
Powered by NewsLook.com
Ark. Man Finds 6-Carat Diamond At State Park

Ark. Man Finds 6-Carat Diamond At State Park

Newsy (Apr. 18, 2014) An Arkansas man has found a nearly 6.2-carat diamond, which he dubbed "The Limitless Diamond," at the Crater of Diamonds State Park. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

More Coverage


Rising CO2 Levels at End of Ice Age Not Tied to Pacific Ocean

Oct. 3, 2011 At the end of the last Ice Age, atmospheric carbon dioxide levels rose rapidly as the planet warmed; scientists have long hypothesized that the source was CO2 released from the deep ocean. But a new ... read more
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins