Date of Award:

12-2023

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Geosciences

Committee Chair(s)

Donald Penman

Committee

Donald Penman

Committee

Dennis Newell

Committee

Simon (S.-Y.) Wang

Abstract

The Paleocene-Eocene Thermal Maximum (PETM) is a geologic climate event that is studied heavily due to the similarities to anthropogenic climate change. This event occurred approximately 56 million years ago (Ma) and is characterized by a rapid release of carbon into the atmosphere, which resulted in an increase in temperature and a change in global climate events such as changes in patterns of evaporation and precipitation. We see this effect occurring in modern anthropogenic climate change due to the burning of fossil fuels releasing carbon dioxide (CO2) into the atmosphere. In this study I use elemental data of foraminifera, microorganisms that form calcium carbonate shells, as proxies for temperature and salinity to determine climatic shifts over the PETM in the tropical Atlantic Ocean. Those reconstructions are compared to climate model simulations as a data-model comparison to evaluate the confidence of climate models. Based on the observed and modeled data, it is clear that the relationship between temperature and CO2 is well understood: as CO2 concentrations increase, there is an increase in temperature. Modern climate model projections (i.e. CMIP6) agree with this observation. The changes in evaporation and precipitation are not as well-understood as the changes in temperature. Modern climate projections predict an increase in evaporation in areas where droughts are common and an increase in precipitation in areas that experience extreme rain events, such as monsoons. The paleoclimate data shows that this simple relationship becomes more complicated at very high pCO2: both our reconstructions and climate modeling suggest a subdued or opposite response at the extremely high pCO2 of the peak PETM. Studying past climate events will help bolster our understanding of how the earth will respond to a large, rapid release of CO2 in the atmosphere.

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