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The Habitable Planet: A Systems Approach to Environmental Science 

Many Planets, One Earth Scientists

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Daniel P. Schrag
Daniel Schrag is professor of Earth and planetary sciences and environmental engineering at Harvard University and the director of the Harvard University Center for the Environment. Schrag studies climate and climate change over the broadest range of Earth history. Schrag received a B.S. from Yale in 1988. He majored in political science and geology, beginning an interest in science and policy that continues to this day. As a graduate student at Berkeley, Schrag was introduced to geochemistry and paleoclimatology through his work developing new methods for reconstructing ancient climates. After receiving his Ph.D. in 1993, Schrag taught at Princeton until 1997, when he moved to Harvard’s Department of Earth and Planetary Sciences. In his research, Schrag applies a variety of techniques from analytical chemistry to a wide range of Earth materials including trees, corals, and deep sea sediments, using the data to understand the chemical and physical evolution of the atmosphere and ocean and the relationship to the evolution of life. He has studied the physical circulation of the modern ocean, focusing on El Niño and the tropical Pacific. He has worked on theories for Pleistocene ice-age cycles over the last few hundred thousand years. He helped develop the Snowball Earth hypothesis, proposing that a series of global glaciations occurred between 750 and 580 million years ago that may have contributed to the evolution of multicellular animals. He has also worked on the early climates of Earth and Mars nearly 4 billion years ago. He is currently working with economists and engineers on technological approaches to mitigating future climate change. Among various honors, Schrag was awarded a MacArthur Fellowship in 2000.


Featured Scientists

Paul F. Hoffman
Paul Hoffman is the Sturgis Hooper Professor of Geology in the Department of Earth and Planetary Sciences at Harvard University. As a life-long field geologist, he has studied the inception of the North American continent, the sequence of supercontinents prior to Pangea, and the global ‘snowball’ glaciations from which the first complex animals emerged. // Read interview transcript


Andrew H. Knoll
Andrew Knoll is the Fisher Professor of Natural History in the Department of Organismic and Evolutionary Biology at Harvard University. He is broadly interested in the evolution of life, the evolution of Earth surface environments, and the relationships between the two. His work focuses in part on the first four billion years of Earth’s history – Archean and Proterozoic paleontology and biogeochemistry, including the early diversification of prokaryotic metabolisms, the initial radiation of eukaryotic life, and the rise of large complex algae and animals. He is also actively involved in Mars exploration, both as part of NASA’s 2004 MER missions and in the planning for future landings. // Read interview transcript

Series Directory

The Habitable Planet: A Systems Approach to Environmental Science 


Harvard Smithsonian Center for Astrophysics in association with the Harvard University Center for the Environment. 2007.
  • ISBN: 1-57680-883-1