101st Annual Meeting of the Pennsylvania Academy of Science Keynote Address
Saturday April 18, 2026
Co-evolution of Earth’s Biosphere and Geosphere: Past, Present and Future of a Living Planet
Dr. Dork Sahagian, Ph.D.
Lehigh University
How did we get here? Where are we? Where are we going? Earth is a living planet, and our own history is bound to the rocks, water, air and sunlight that surrounds us. While geologists can tell us how we got here and sociologists may be able to explain where we are, where we are going is a more complicated question because it depends on what we and our descendants decide to do. Although human history is a blink of the eye in the geologic record, it is founded on the co-evolution of biological and geological processes over the past 4.6 billion years without which we would not be here to tell the story. This presentation will describe how biology and geology co-evolved to bring us to the present state and contemplate where we may be headed.
Dork Sahagian (B.S. in Physics from Rensselaer Polytechnic Institute, M.S. in Geosciences from Rutgers University, Ph.D. in Geophysics from the University of Chicago) is a Professor of Earth & Environmental Sciences at Lehigh University. He served the Navy as a NORDA Oceanographer at Dartmouth College, Associate Research Scientist at Lamont-Doherty Earth Observatory (Columbia University), and Research Scientist at the Byrd Polar Research Center (Ohio State University). He then served as Executive Director of the Global Analysis, Integration, and Modelling Task Force of the International Geosphere Biosphere Programme (IGBP/GAIM) at the Institute for the Study of Earth, Oceans, and Space at the University of New Hampshire after which he moved to Lehigh University, where he served as Director of the Environmental Initiative from 2004 to 2010.
Professor Sahagian conducts research in paleoclimatology, volcanology, stratigraphy, geodynamics and tectonics, global hydrology, sea level, the environmental impacts of human activities, and science education. Part of his research led him to coauthor the pivotal reports of the Intergovernmental Panel on Climate Change (IPCC), which was jointly awarded the 2007 Nobel Peace Prize with former vice president Al Gore. He also served as the Principal Scientific Reviewer for Global Environmental Outlook (GEO-5) of the United Nations Environment Programme (UNEP).
He recently wrote a third edition of his book, “A User’s Guide for Planet Earth” which is used as a textbook in Environmental Science courses nationwide. Toward the goal of understanding of Earth’s processes and sustaining the global environment, he continues to work toward the integration of disparate disciplines in geology, environmental science, technology, policy, and the myriad interactions between people and the world in which we live.