Berner, Robert A. (1935- )

American geochemist

Robert A. Berner's research in sedimentary geochemistry led to the application of mathematical models to describe the physical, chemical, and biological changes that occur in ocean sediment. Berner, a professor of geology and geophysics at Yale University, also developed a theoretical approach to explain larger geochemical cycles, which led to the creation of a model for assessing atmospheric carbon dioxide levels and the greenhouse effect over geological time. A prolific researcher, Berner has written many scientific journal articles and is one of the most frequently quoted earth scientists in the Science Citation Index.

Robert Arbuckle Berner was born in Erie, Pennsylvania, on November 25, 1935, to Paul Nau Berner and Priscilla (Arbuckle) Berner. As a young man, Berner decided to become a scientist because of his propensity for logical thinking. "Science forces you to seek the truth and see both sides of an argument," he told Patricia McAdams. Berner began his academic studies at the University of Michigan where he earned his B.S. in 1957 and his M.S. a year later. He then went to Harvard University and earned his Ph.D. in geology in 1962. He married fellow geology graduate student Elizabeth Marshall Kay in 1959; the couple have three children.

Berner began his professional career at the Scripps Institute of Oceanography in San Diego, where he won a fellowship in oceanography after graduating from Harvard. In 1963, he was appointed assistant professor at the University of Chicago, and two years later he became an associate professor of geology and geophysics at Yale University. Since 1968, Berner has also served as associate editor or editor of the American Journal of Science. He was promoted to full professor at Yale in 1971, and in 1987 he became the Alan M. Bateman Professor of geology and geophysics.

Principles of Chemical Sedimentology, which Berner published in 1971, reflects the interest that has fueled much of his research. Berner sees the application of chemical thermodynamics and kinetics as a valuable tool in unveiling the secrets of sediments and sedimentary rocks. Thus, Berner's is an unconventional approach to sedimentology (the chemical study of sediments rather than the study of chemical sediments). Berner identifies his goal in Principles of Chemical Sedimentology as illustrating "how the basic principles of physical chemistry can be applied to the solution of sedimentological problems." Berner's Early Diagenesis, published in 1980, is a study of the processes over geological time whereby sedimentary materials are converted into rock through chemical reactions or compaction. Because of the frequency with which Early Diagenesis has been quoted, it was declared a Science Citation Classic by the Institute for Scientific Information.

Berner observes in Scientific American that "the familiar biological carbon cycle—in which atmospheric carbon is taken up by plants, transformed through photosynthesis into organic material and then recovered form this material by respiration and bacterial decomposition—is only one component of a much larger cycle: the geochemical carbon cycle." Berner has studied an aspect of this geochemical carbon cycle that is analogous to the transfer of carbon between plants, animals, and their habitats—the "transfer of carbon between sedimentary rocks at or near the earth's surface and the atmosphere, biosphere and oceans." Carbon dioxide is vital to both these aspects of the geochemical carbon cycle, as carbon is primarily stored as carbon dioxide in the atmosphere. Berner's research has contributed to the "BLAG" model (named after Berner and his associates Antonio L. Lasaga and Robert M. Garrels) for assessing the changes in atmospheric levels of carbon dioxide throughout the earth's geological eras. First published in 1983 and subsequently refined, the BLAG model quantifies factors such as degassing (whereby carbon dioxide is released from beneath the earth), carbonate and silicate rock weathering, carbonate formation in oceans, and the rate at which organic matter is deposited on and buried in the earth that enable scientists to assess the climactic conditions of the planet's previous geological eras.

Berner's research on atmospheric carbon dioxide levels includes the study of the greenhouse effect, whereby carbon dioxide and other gases trap excessive levels of radiated heat within Earth's atmosphere, leading to a gradual increase in global temperatures. Since the nineteenth-century industrial revolution, this phenomenon has increased primarily because of the burning of fossil fuels such as coal, oil, and natural gas; also because of deforestation. Berner reports in Scientific American that "slow natural fluctuations of atmospheric carbon dioxide over time scales of millions of years may rival or even exceed the much faster changes that are predicted to arise from human activities." Thus, the study of the carbon cycle is essential to an objective evaluation of the greenhouse effect within larger geological processes. In 1986, Berner published the textbook The Global Water Cycle: Geochemistry and Environment which he co-authored with his wife Elizabeth, who is also a geochemist. The Global Water Cycle reviews the properties of water, marine environments, and water/energy cycles, and includes a discussion of the greenhouse effect. Berner's research has since focused on Iceland where he is investigating how volcanic rock is broken down by weathering and by the plant-life that gradually takes root on it.

Berner enjoys traveling that is associated with his research and likes to help students learn to think creatively for themselves. "I'm very proud of the…graduate students that have received Ph.D.s working with me. I've learned as much from them as they have from me," he told McAdams. Berner served as president of the Geochemical Society in 1983, and he is a member of the National Academy of Sciences, the American Academy of Arts and Sciences, the Geological Society of America, and the Mineral Society. He has chaired the Geochemical Cycles Panel for the National Research Council and served on the National Committee on Geochemistry, the National Science Foundation Advisory Committees on Earth Sciences and Ocean Sciences, and the National Research Council Committee on Oceanic Carbon. He has received numerous awards, including an honorary doctorate from the Université Aix-Marseille III in France in 1991 and Canada's Huntsman Medal in Oceanography in 1993. His hobbies include Latin American music, tennis, and swimming.

See also Greenhouse gases and greenhouse effect; Weathering and weathering series