Date of Award

1-24-2024

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Earth Sciences

Advisor(s)

Tripti Bhattacharya

Keywords

Climate dynamics;Climate model;CMIP6;Organic geochemistry;Paleoclimate;Pliocene

Abstract

Anthropogenic climate change impacts will vary spatially, temporally, and in magnitude due to Earth's complex climate dynamics. Though the sheer quantity and resolution of climate data and observations is increasing, analyses of these data alone will not permit a complete and thorough examination of our current and, more importantly, future climate scenario. Paleoclimatology provides the sole analogue for projected 21st century equilibrated climate under anthropogenic carbon emissions, and must be studied in order to understand and anticipate the potential future impacts of increased atmospheric greenhouse gas concentrations. Here I conduct a comprehensive study of climate dynamics through the use of theoretical and observational methods, including climate modelling, organic geochemistry, and various computational methods. I focus my research initially on the warm Pliocene epoch due to its relative proximity to today in comparison to other geologic periods that might be considered an analogue for future climate change scenarios. I also conduct analyses on historical climate later in my research when studying marine heatwaves (MHWs). Through this work I resolve organic geochemical records of paleo-sea surface temperature (SST) in the north Pacific with fully-coupled climate models from the PlioMIP2 (Pliocene Model Intercomparison Project 2) project. This work clarifies model accuracy in recreating the region's ocean surface warming, thus permitting the thorough examination of simulated climate dynamics in this critical marine region in current climate models. Next, I analyze terrestrial organic biomarkers to study hydroclimate changes through time in the western continental US, a region already experiencing rapid climate change. Finally, I undertake a rigorous analysis of CMIP6 historical model simulations to clarify MHW dynamics and model-observation discrepancies. Ultimately, this work contributes to the understanding of some of the more pressing and complex questions in climate science, including (1) the role of clouds in climate models and in a warmer world; (2) future hydrologic changes in the American west; and (3) the ability of climate models to study and recreate extreme climate phenomena like MHWs.

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Open Access

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