The Department of Geology and Geophysics at Yale University pioneered Earth system science and continues exploring the complex interplay between the biosphere, ocean, land surface, atmosphere, and climate. Interests in the department are broad and far-reaching, encompassing a wide range of temporal and spatial scales from the Precambrian to the Present, surface to subsurface, from astrobiology to microbiology.

Our interdisciplinary approach applies a range of paleontological, chemical, biological, and numerical techniques. Stable isotope compositions of specific organic molecules (biomarkers), biodiversity of microfossils, and isotope and elemental chemistries of biogenic phases are used to study the physical and chemical character of ancient oceans, atmospheres, and modern marine systems. Oxygen isotope proxies from biogenic phosphate are being developed to study paleotempertures, microbial P utilization, and phosphorous cycling in modern marine and terrestrial systems. We apply radiogenic isotopes to help resolve elemental mass balances and provide a history of continental weathering. These results and data from a variety of fields are combined in numerical Earth system models to calculate the composition of ancient atmospheres, with a focus on the global carbon cycle and the history of atmospheric oxygen. Finally, as part of the continued expansion of the areas encompassed by geology the integration of the data and techniques from biomineralization and medical geology offer direct applications to today's important environmental questions.

Faculty members and research affiliates associated with the group include Robert Berner, Ruth Blake, Derek Briggs, David Evans, Leo Hickey, Mark Pagani, Danny Rye, Ellen Thomas, and Karl Turekian.

We have several laboratories, including the lab for Microbial Geochemistry and Geomicrobiology and the Earth System Center for Stable Isotope Studies.