Date:  March 1, 2011






WASHINGTON — Rocks and sediments that are millions of years old could hold clues to how the Earth's future climate would respond in an environment with high levels of atmospheric greenhouse gases, says a new report from the National Research Council.  Through an integrated, "deep-time" climate research program, these ancient geologic records could enable scientists to better understand how climate behaved during past warm periods and major climate transitions, as well as provide insights into greenhouse gases' role during warmer climates and the critical climate thresholds at which rapid and potentially permanent changes may occur.


Earth has had two fundamentally different climate states -- an "icehouse" state with periods of growth and depletion of continental ice sheets and a "greenhouse" state characterized by much higher temperatures globally and small or no ice sheets.  Although Earth has been in an increasingly cool icehouse state for the past 30 million years, a warmer greenhouse state was more common for most of the past 600 million years.


"Ancient rocks and sediments hold the only records of major, and at times rapid, transitions across climate states and offer the potential for a much better understanding of the long-term impact of climate change on atmosphere and ocean circulation, ice sheets, sea-level rise, ocean acidification, and the health of Earth's ecosystems," said Isabel Montañez, chair of the committee that wrote the report and a professor in the department of geology at the University of California, Davis.  "Analyzing the planet's deep-time climate past will provide important insights into various climate processes that have not operated or have operated quite differently during our existing icehouse state."


The committee identified several elements needed for an integrated, deep-time climate research program that would study how climate responded over Earth's different climate states.  With the potential to produce important results over the next decade, this program would examine how climate responds to increased atmospheric carbon dioxide and other greenhouse gases, and it would clarify the processes that lead to anomalously warm polar and tropical regions and the impact on marine and terrestrial life.  In addition, the program would focus on the stability of sea level and ice sheets, changing regional climates, tipping points and abrupt transitions, and ecosystem thresholds and resilience -- all in warm world environments.


The report was sponsored by the National Science Foundation, U.S. Geological Survey, and Chevron Corp.  The National Academy of Sciences, National Academy of Engineering, Institute of Medicine, and National Research Council make up the National Academies.  They are independent, nonprofit institutions that provide science, technology, and health policy advice under an 1863 congressional charter.  Committee members, who serve pro bono as volunteers, are chosen by the Academies for each study based on their expertise and experience and must satisfy the Academies' conflict-of-interest standards.  The resulting consensus reports undergo external peer review before completion.  For more information, visit  A committee roster follows.




Jennifer Walsh, Media Relations Officer

Luwam Yeibio, Media Relations Assistant

Office of News and Public Information

202-334-2138; e-mail 


Pre-publication copies of Understanding Earth's Deep Past: Lessons for Our Climate Future are available from the National Academies Press; tel. 202-334-3313 or 1-800-624-6242 or on the Internet at  Reporters may obtain a copy from the Office of News and Public Information (contacts listed above).

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Division on Earth and Life Studies

Board on Atmospheric Sciences and Climate


Board on Earth Sciences and Resources


Committee on the Importance of Deep-Time Geologic Records for Understanding Climate Change Impacts

Isabel P. Montanez (chair)
Department of Geology
University of California

Thomas J. Algeo
Department of Geology
University of Cincinnati


Mark A. Chandler
Associate Research Scientist
Center for Climate Systems Research
Columbia University
New York City

Kirk R. Johnson
Vice President of Research and Collections, and
Chief Curator
Denver Museum of Nature and Science

Martin J. Kennedy
School of Earth and Environmental Sciences
The University of Adelaide


Dennis V. Kent *
Board of Governors Professor
Department of Earth and Planetary Sciences
Rutgers University
Piscataway, N.J.


Jeffrey T. Kiehl
Senior Scientist
Climate Change Research Section
National Center for Atmospheric Research
Boulder, Colo.

Lee R. Kump
Department of Geosciences
The Pennsylvania State University
University Park


Richard D. Norris
Professor of Paleobiology
Scripps Institution of Oceanography
La Jolla, Calif.  

A. Christina Ravelo
Professor of Ocean Studies
Department of Ocean Sciences
University of California
Santa Cruz

Karl K. Turekian *
Sterling Professor
Department of Geology and Geophysics
Yale University
New Haven, Conn.




David Feary

Study Director



* Member, National Academy of Sciences