to trace CO 2 levels of long ago
Yale geologist Mark Pagani and his colleagues have mapped the first detailed history of atmospheric carbon dioxide between 45 million and 25 million years ago based on stable isotopes of carbon as part of a National Science Foundation study reported in Science Express.
"Through the energy we consume, each of us makes a contribution to increasing greenhouse gases, such as carbon dioxide and methane, in the Earth's atmosphere," says Pagani, assistant professor in the Department of Geology and Geophysics. "To understand the implications of these actions for the future, scientists look to the past to gain a better understanding of Earth's climate system under high greenhouse gas conditions."
The findings were based on calibration of carbon-containing compounds produced by ancient sea surface algae that were recently isolated in deep sea drill cores.
The data indicates that between 45 million and 34 million years ago the atmospheric carbon dioxide level was up to five times greater than today, with a sharp decrease and then stabilization to near modern day levels between 34 million and 25 million years ago.
During the early part of the Paleogene Period, from 65 million to 34 million years ago, global climates were much warmer than today with very little ice present at the poles. The boundary of the Oligocene and Eocene Epochs 33.7 million years ago was marked by rapid global cooling and the formation of large continental ice sheets on the Antarctic.
"Before this study, the relationship between the global climate and the concentration of carbon dioxide in the atmosphere during the late Eocene and Oligocene was largely unknown," says Pagani, who is recognized for his reconstruction of past atmospheric carbon dioxide levels between 25 million and 8 million years ago.
They also present intriguing evidence that the sharp drop in carbon dioxide level between 33 million and 25 million years ago prompted the origin of economically important land plants that are sensitive to atmospheric carbon dioxide levels, such as corn and sugarcane.
"The onset and stabilization of ice sheets at the same time as a decline in carbon dioxide illustrates the importance of atmospheric carbon dioxide as an agent of both climate and biological change," Pagani says.
Collaborators were Brett Tipple from Yale, James C. Zachos and Stephen Bohaty from the University of California at Santa Cruz and Katherine Freeman from Pennsylvania State.
-- By Janet Rettig Emanuel
T H I S
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New alumni fellow elected
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Study: Monkeys ape humans' economic traits
Richard Shaw departs for Stanford post
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Exhibit features post-Civil War works by 'artful storyteller'
Yale alumni, teachers win Tony Awards
ENDOWED PROFESSORSHIPS
Philosopher Keith DeRose: Allison Foundation Chair
Phyllis Granoff: Hixon Chair in World Religions
Thomas Kavanagh: Street Professor of French
Jeffrey Sonnenfeld: Crown Chair in ManagementLaw School project exploring the information society . . .
Poll shows public's distaste with foreign oil dependence
Scientists discover how plants protect themselves from infection
Team seeking 'perfume' to control malaria-carrying mosquitoes
Geologists use ancient sea algae to trace CO2 levels of long ago
Study shows how sex discrimination in job hiring is able to endure
YSN study shows effectiveness of preschool health screenings
SCHOOL OF MEDICINE NEWSTeam to develop new system for testing potential vaccines
Senior citizens' television-watching habits affect their views . . .
Grant funds study of intestinal condition common in tiny babies
Yale center joins with Bike Across America to raise funds . . .
Alzheimer's disease patients sought for testing . . .
Scientists' discovery of protein amplification in melanoma . . .
Discovery of breast cancer growth regulator may help . . .
Patients disfigured by facial trauma suffer host of problems
Study shows how sex discrimination in job hiring is able to endure
New studies aim to benefit women's health
Study links an inherited pain disorder to specific gene mutation
Spotlight on Sports
Athletics archive now in library's collection
Three promoted to post of associate provost
Event to explore role of faith in the corporate world
In Memoriam: Dick Wittink, marketing expert and SOM teacher
Five faculty members awarded Guggenheim Fellowships for research
Event explored how libraries can benefit city schools
New alumni lauded for efforts to improve public schools
Yale Books in Brief
Campus Notes
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