Navigation Links
CO2 drop and global cooling caused Antarctic glacier to form
Date:2/26/2009

New Haven, Conn. 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 transitionone 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."


'/>"/>

Contact: Janet Rettig Emanuel
janet.emanuel@yale.edu
203-432-2157
Yale University
Source:Eurekalert  

Related biology news :

1. Global Warming and the Habitability of Planet Earth, Sept. 26
2. Green skies: Engineers work may reduce jet travels role in global warming
3. Scientists in first global study of poison gas in the atmosphere
4. North Americas northernmost lake affected by global warming
5. IEEE-USA innovation forum will help prepare US tech leaders to prosper in a global marketplace
6. Majority of Americans want local action on global warming, says poll
7. International team of scientists warns of climate changes impact on global river flow
8. Changing the global dietary environment
9. Global deal fuels QUTs world-changing research
10. NIH hosts event to launch Council of Science Editors global theme issue
11. Agricultural soil erosion is not adding to global warming
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
CO2 drop and global cooling caused Antarctic glacier to form
(Date:4/15/2016)... , April 15, 2016  A new partnership ... more accurate underwriting decisions in a fraction of ... competitively priced and high-value life insurance policies to ... With Force Diagnostics, rapid testing (A1C, ... data readings (blood pressure, weight, pulse, BMI, and ...
(Date:4/13/2016)... CHICAGO , April 13, 2016  IMPOWER physicians ... are setting a new clinical standard in telehealth ... By leveraging the higi platform, IMPOWER patients can ... weight, pulse and body mass index, and, when they ... quick and convenient visit to a local retail location ...
(Date:3/29/2016)... , March 29, 2016 ... "Company") LegacyXChange "LEGX" and SelectaDNA/CSI Protect are pleased to ... ink used in a variety of writing instruments, ensuring ... of originally created collectibles from athletes on LegacyXChange will ... analysis of the DNA. Bill Bollander ...
Breaking Biology News(10 mins):
(Date:6/23/2016)... ... June 23, 2016 , ... ... of its second eBook, “Clinical Trials Patient Recruitment and Retention Tips.” Partnering with ... in this eBook by providing practical tips, tools, and strategies for clinical researchers. ...
(Date:6/23/2016)... , June 23, 2016   Boston ... of novel compounds designed to target cancer stemness ... has been granted Orphan Drug Designation from the ... treatment of gastric cancer, including gastroesophageal junction (GEJ) ... inhibitor designed to inhibit cancer stemness pathways by ...
(Date:6/23/2016)... 23, 2016 A person commits a crime, and ... to track the criminal down. An outbreak of ... Drug Administration (FDA) uses DNA evidence to track down the ... Sound far-fetched? It,s not. The FDA has increasingly used a ... of foodborne illnesses. Put as simply as possible, whole genome ...
(Date:6/23/2016)... ... June 23, 2016 , ... Charm Sciences, Inc. is ... has received AOAC Research Institute approval 061601. , “This is another AOAC-RI approval ... Bob Salter, Vice President of Regulatory and Industrial Affairs. “The Peel Plate methods ...
Breaking Biology Technology: