Robert A. Berner

Robert A. Berner
Robert A.
Earth and Environmental Science
Benjamin Franklin Medal
Yale University | New Haven, Connecticut
For deepening our understanding of the Earth system through studies of the chemistry of geologic processes and their influence on the atmosphere and oceans.

The processes and cycles that arise through the interactions of Earth's biota, its soil and rocks, its ever-changing atmosphere, and its vast oceans are as intricate as the workings of the most complex organism. Geochemistry is the study of the chemical elements that comprise our planet, their distribution through the ages, and their effect on the planet through various processes. For nearly 50 years, Robert Berner has been exploring the cycles of time and geochemical phenomena that shape the past, present, and future of the Earth.

Berner earned B.S. and M.S. degrees from the University of Michigan, then his Ph.D. in geology from Harvard. A fellowship at Scripps Institution of Oceanography started him on the work that first brought him wide recognition—the formation and composition of marine sediments. Just as fossils of plants and animals depict the history of life, sediment layers tell the story of changing environmental conditions over Earth's history. More than simply repositories of the past, sediments are active chemical systems, controlling the amounts of important elements such as oxygen, carbon, and sulfur in the environment. His studies of diagenesis, the changes undergone by sediments after their deposition but before their solidification, highlighted the role of biology in how elements are distributed. His book, Early Diagenesis: A Theoretical Approach, is widely regarded as one of the seminal works in the field.

The amount of organic carbon from plants and animals buried in rocks and sediment is largely responsible for controlling atmospheric oxygen content, and Berner demonstrated that in some marine sediments, organic matter is not buried but instead converted to pyrite (an iron sulfide), possibly accounting for approximately 20% of the oxygen in our atmosphere. The formation and burial of pyrite also affects the sulfur content of the world's oceans, and seawater pH is also strongly tied to calcium carbonate from marine sediments. He translated his masterful fieldwork into influential computer models that show the vital linkage between the Earth's carbon, sulfur, and oxygen cycles. Berner's BLAG model (incorporating the names of collaborators Tony Lasaga and Bob Garrels) was recognized as the first truly large scale, dynamic geochemical model of the chemical cycles that have governed the composition of Earth's atmosphere and oceans over eons. The model was confirmed by the geologic record and by experimental proxy research. Berner expanded and revised it into GEOCARB, an even broader and more ambitious model that does nothing less than explain the changes in atmospheric carbon dioxide over Earth's past. Berner's robust models have provided the context with which to better understand the impact of rising levels of carbon dioxide and other greenhouse gases. He has provided expert consultation to the U.S. Senate and the general public on this subject. Berner's research has also had a major impact in the study of weathering processes, particularly of silicate minerals. Weathering is another means by which rocks are broken down with chemical compounds and interact with the atmosphere, and thus provides another part of the grand picture of Earth's geochemical processes.

Based at Yale University for most of his career, Robert Berner has spent decades ranging through the limits of Earth, from the shadows of the past to our troubled present and uncertain future, moving from the depths of the ocean to the atmosphere around us to the ground beneath. His work in understanding the cycles of geologic dissolution, change, and renewal serves to emphasize the fundamental ties that bind together the workings of our planet.

Information as of April 2013