Featured Research

from universities, journals, and other organizations

Sunlight Has More Powerful Influence On Ocean Circulation And Climate Than North American Ice Sheets

Date:
November 7, 2008
Source:
University of California - Santa Barbara
Summary:
A study reported in Nature disputes a longstanding picture of how ice sheets influence ocean circulation during glacial periods.

A study reported in Nature disputes a longstanding picture of how ice sheets influence ocean circulation during glacial periods.

The distribution of sunlight, rather than the size of North American ice sheets, is the key variable in changes in the North Atlantic deep-water formation during the last four glacial cycles, according to the article. The new study goes back 425,000 years, according to Lorraine Lisiecki, first author and assistant professor in the Department of Earth Science at the University of California, Santa Barbara.

Lisiecki and her co-authors studied 24 separate locations in the Atlantic by analyzing information from ocean sediment cores. By observing the properties of the shells of tiny marine organisms, called foraminifera, found in these cores, they were able to deduce information about the North Atlantic deep water formation. Scientists can discern historical ocean temperature and circulation patterns through the analysis of the chemical composition of these marine animals.

Previously, scientists relied on a study called "Specmap," performed in 1992, to find out how different parts of the climate system interacted with one another during glacial cycles. Specmap analyzed ocean circulation at only one place in the Atlantic.

"What I found was that the one site that the Specmap study used actually didn't match most of the other sites in the Atlantic," said Lisiecki. "They just happened to have a strange site that didn't behave like most of the other sites. The other sites show that the circulation is not responding to the ice volume, but that it is responding to changes in the distribution of sunlight."

Previously, scientists believed that deep ocean circulation –– the amount of water formed in the North Atlantic that goes into the deep ocean –– varied or responded according to the amount of ice volume in the Northern Hemisphere. The prevailing idea was that when ice ages occur, with large sheets of ice over North America, the amount of North Atlantic deep water is reduced.

"That's an important part of circulation," said Lisiecki. "The Gulf Stream brings up warm water from the tropics and that water is turned into this North Atlantic deep water that then sinks and moves southward at depth so you have a cycle. Warm water moves northward and then cools and sinks. That's the North Atlantic deep water formation process."

When warm water in the Gulf Stream comes north, it brings heat to the North Atlantic and Europe and then sinks in the North Atlantic and flows back southward at a depth of 3,000 meters.

"This is fairly important for the climate because it brings this heat northward," said Lisiecki. "The Specmap study in 1992 found that circulation is reduced when you have large ice sheets –– presumably because you have less of this North Atlantic deep water forming. Our results show that this is not always true."

She explained that the new data changes our understanding about how the different parts of the climate system are interacting with one another and in particular the influence of the ice sheets on climate.

"Because the ice sheets are so large, it was a nice simple story to say that they were having the predominant influence on all the parts of the climate system," said Lisiecki. "But our study showed that this wasn't the only important part of the changes in climate. The distribution of sunlight is the controlling factor for North Atlantic deep water formation.

"Our study tells us a lot about how the ocean circulation is affected by changes in climate," she adds. "The ocean does not always follow the climate; it exerts its own impact on climate processes. In other words, the ocean circulation doesn't just follow along with the rest of the climate, it actually changes in different ways than the ice sheets during glacial cycles."


Story Source:

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


Cite This Page:

University of California - Santa Barbara. "Sunlight Has More Powerful Influence On Ocean Circulation And Climate Than North American Ice Sheets." ScienceDaily. ScienceDaily, 7 November 2008. <www.sciencedaily.com/releases/2008/11/081106153633.htm>.
University of California - Santa Barbara. (2008, November 7). Sunlight Has More Powerful Influence On Ocean Circulation And Climate Than North American Ice Sheets. ScienceDaily. Retrieved October 1, 2014 from www.sciencedaily.com/releases/2008/11/081106153633.htm
University of California - Santa Barbara. "Sunlight Has More Powerful Influence On Ocean Circulation And Climate Than North American Ice Sheets." ScienceDaily. www.sciencedaily.com/releases/2008/11/081106153633.htm (accessed October 1, 2014).

Share This



More Earth & Climate News

Wednesday, October 1, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Raw: 12 More Bodies Found on Japan Volcano

Raw: 12 More Bodies Found on Japan Volcano

AP (Oct. 1, 2014) — A dozen more bodies were found Wednesday as Japanese rescuers resumed efforts to find survivors and retrieve bodies of those trapped by Mount Ontake's eruption. (Oct. 1) Video provided by AP
Powered by NewsLook.com
Cultural Learning In Wild Chimps Observed For The First Time

Cultural Learning In Wild Chimps Observed For The First Time

Newsy (Oct. 1, 2014) — Cultural transmission — the passing of knowledge from one animal to another — has been caught on camera with chimps teaching other chimps. Video provided by Newsy
Powered by NewsLook.com
Raw: Trapped Scientist Rescued from Cave in Peru

Raw: Trapped Scientist Rescued from Cave in Peru

AP (Oct. 1, 2014) — A Spanish scientist, who spent 12 days trapped about 1300 feet underground in a cave in Peru's remote Amazon region, was rescued on Tuesday. (Oct. 1) Video provided by AP
Powered by NewsLook.com
Media, Industry Groups React To Calif. Plastic Bag Ban

Media, Industry Groups React To Calif. Plastic Bag Ban

Newsy (Sep. 30, 2014) — California is the first state in the country to ban single-use plastic bags in grocery, liquor and convenience stores. 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:

Strange & Offbeat Stories

 

Plants & Animals

Earth & Climate

Fossils & Ruins

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