Featured Research

from universities, journals, and other organizations

Carbon Dioxide Drop And Global Cooling Caused Antarctic Glacier To Form

Date:
February 27, 2009
Source:
Yale University
Summary:
Global climate rapidly shifted from a relatively ice-free world to one with massive ice sheets on Antarctica about 34 million years ago. What happened? What changed? Scientists offer a new perspective on the nature of changing climatic conditions across this greenhouse-to-icehouse transition -- one that refutes earlier theories and has important implications for predicting future climate changes.

Projection of the what the first Antarctic ice sheet might have looked like as the global climate cooled about 33.5 million years ago. Antarctica is in gray, with the ice sheet shown in meters of ice thickness. The ice sheet is continental in scale, but somewhat smaller than today. The estimate is based on prior modeling work of DeConto and Pollard and is supported by this new data study.
Credit: DeConto & Pollard / Nature

Global climate rapidly shifted from a relatively ice-free world to one with massive ice sheets on Antarctica about 34 million years ago. What happened? What changed? A team of scientists led by Yale geologists offers a new perspective on the nature of changing climatic conditions across this greenhouse-to-icehouse transition — one that refutes earlier theories and has important implications for predicting future climate changes.

Detailed in the February 27 issue of Science, their data disproves a long-held idea that massive ice growth in the Antarctic was accompanied by little to no global temperature change.

This report shows that before the Southern Hemisphere ice expansion, high-latitude temperatures were at least 10C (about 18˚F) warmer than previously estimated and that there was a 5˚C - 10˚C drop in surface-water temperature during the climate transition.

"Previous reconstructions gave no evidence of high-latitude cooling," according to senior author Mark Pagani, professor of geology and geophysics at Yale. "Our data demonstrate a clear temperature drop in both hemispheres during this time."

Their conclusions are based on sea-surface "temperature proxies" – calculations of temperature based on the distribution of specific organic molecules from ancient plankton that only lived at certain temperatures and were later preserved in ocean sediments. These molecules were assayed in ocean cores collected by the Integrated Ocean Drilling Program (IODP) and earlier marine programs that study Earth history by coring deep-ocean sediments and crust around the world.

"Temperatures in some regions, just before the Antarctic glaciers formed, were surprisingly higher than current climate models predicted, suggesting that these models underestimate high-latitude warming under high CO2 conditions," said lead author Zhonghui Liu, Pagani's postdoctoral associate who is now an assistant professor at the University of Hong Kong. Further, he said, the substantial cooling that occurred in both Northern and Southern high latitudes suggests that a decline in CO2 level, rather than a localized change of ocean circulation drove the climate transition.

The ice formed over Antarctica in about 100,000 years, which is an "overnight" shift in geological terms. "Just over thirty-five million years ago, 'poof,' there was an ice sheet where there had been subtropical temperatures before," said co-author Matthew Huber of Purdue University.

Another theory refuted by this study is the notion that ice-expansion also occurred in the Northern Hemisphere during this time — a supposition poorly supported by physical evidence of glacier formation in that region, say the Yale scientists.

There are about 70 meters of vertical sea level rise represented in the ice sheets of Antarctica. And, there are many questions regarding the glacier's stability, the temperature thresholds that would cause radical glacier melting, and the rate at which it would change, according to Pagani. "Our findings point to the difficulty of modeling accurate temperatures under higher CO2 in this critical region."

Other authors on the article were David Zinniker at Yale, Robert DeConto and Mark Leckie at the University of Massachusetts, Amherst, Matthew Huber at Purdue University, Henk Brinkhuis at Utrecht University, and Sunita R. Shah and Ann Pearson at Harvard. The research was supported by funds from the National Science Foundation and Yale University and computation was performed using resources of the Rosen Center for Advanced Computing at Purdue.


Story Source:

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


Cite This Page:

Yale University. "Carbon Dioxide Drop And Global Cooling Caused Antarctic Glacier To Form." ScienceDaily. ScienceDaily, 27 February 2009. <www.sciencedaily.com/releases/2009/02/090226141146.htm>.
Yale University. (2009, February 27). Carbon Dioxide Drop And Global Cooling Caused Antarctic Glacier To Form. ScienceDaily. Retrieved October 22, 2014 from www.sciencedaily.com/releases/2009/02/090226141146.htm
Yale University. "Carbon Dioxide Drop And Global Cooling Caused Antarctic Glacier To Form." ScienceDaily. www.sciencedaily.com/releases/2009/02/090226141146.htm (accessed October 22, 2014).

Share This



More Earth & Climate News

Wednesday, October 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Traditional Farming Methods Gaining Ground in Mali

Traditional Farming Methods Gaining Ground in Mali

AFP (Oct. 20, 2014) He is leading a one man agricultural revolution in Mali - Oumar Diatabe uses traditional farming methods to get the most out of his land and is teaching others across the country how to do the same. Duration: 01:44 Video provided by AFP
Powered by NewsLook.com
How Detroit's Money Woes Led To U.N.-Condemned Water Cutoffs

How Detroit's Money Woes Led To U.N.-Condemned Water Cutoffs

Newsy (Oct. 20, 2014) The United Nations says water is a human right, but should it be free? Detroit has cut off water to residents who can't pay, and the U.N. isn't happy. Video provided by Newsy
Powered by NewsLook.com
Hey, Doc! Sewage, Beer and Food Scraps Can Power Chevrolet’s Bi-Fuel Impala

Hey, Doc! Sewage, Beer and Food Scraps Can Power Chevrolet’s Bi-Fuel Impala

3BL Media (Oct. 20, 2014) Hey, Doc! Sewage, Beer and Food Scraps Can Power Chevrolet’s Bi-fuel Impala Video provided by 3BL
Powered by NewsLook.com
White Rhino's Death In Kenya Means Just 6 Are Left

White Rhino's Death In Kenya Means Just 6 Are Left

Newsy (Oct. 20, 2014) Suni, a rare northern white rhino at Ol Pejeta Conservancy, died Friday. This, as many media have pointed out, leaves people fearing extinction. 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