P2C2: P-E Land-C: Terrestrial Mediation of Carbon Cycle Response Through the Paleocene-Eocene Thermal Maximum

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This award to the University of Utah will support field, laboratory, and modeling studies to constrain the role of terrestrial biogeochemical change in modulating the environmental and climatic evolution of the Paleocene-Eocene thermal maximum (PETM). The PETM is a well-documented geological episode of carbon-cycle induced global change that had major repercussions on Earth's environmental and biotic systems. Although a general understanding of the causes and nature of PETM change has been established, a number of anomalous characteristics of the event, including its long duration, high apparent climate sensitivity, and rapid termination, remain unexplained. This project will determine whether changes in the terrestrial critical zone, including carbon storage in land plants and soils, formation of inorganic soil carbonate, and burial of organic and inorganic carbon in continental sedimentary rocks, occurred during the PETM and contributed to the pattern of global change observed during the event. Field studies and lab analyses will document critical zone carbon storage changes at sites in the western USA and Spain and reconstruct local environmental conditions that accompanied these changes. New computer model components will be developed and applied to evaluate the degree to which the observed changes were globally significant and the patterns of global climatic and carbon cycle change that they would have induced, thus providing a more comprehensive understanding of the PETM event. This new information will be incorporated in educational materials, targeted at the graduate, undergraduate, and high-school levels, that communicate the role of the carbon cycle coupled Earth system change over geological and human timescales.Continental ecosystems store a vast amount of carbon, which is potentially easily transferred to or taken up from the atmosphere, affecting global climate. The response of these systems to global change represents a major source of uncertainty in projections of future environmental conditions, as well as a fundamental unknown in our understanding of the geological record of past climate. This work will test ideas about how carbon storage changes as global climate warms, developed based on the study of modern ecosystems, through a focused study of one of the best-documented episodes of rapid climatic warming in the geologic record. The results will improve our understanding of the role of terrestrial carbon cycle feedback as a mediator of global change, advancing our ability to interpret the paleoclimate record and project future changes in Earth's climate.