A 30,000-year Thermocline Temperature Paleo-reconstruction using Mg/Ca Analysis on N. dutertrei: Implications for Eastern Equatorial Pacific Paleo-ENSO

Undergraduate Honors Thesis

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Citeable URL: https://scholar.colorado.edu/concern/undergraduate_honors_theses/8c97kr771

Abstract

The equatorial Pacific is a body of water that plays a vital role in regulating the regional weather and global climate. Understanding the long-term ENSO variability during Last Glacial Maximum (LGM) and Holocene is critical for future climate predictions and assessments. However, the proxy records and models show mixed results. Thermocline temperature reconstruction may be a potential indicator of the mean state of the tropical Pacific associated with ENSO as it is less affected by surface seasonal variation. In this research, we reconstructed the last 30,000 years' thermocline temperature record using core RC13-140 from the Eastern Equatorial Pacific (EEP) region. The temperatures were calculated using Mg/Ca data from shells of thermocline-dwelling planktonic foraminifera species, Neogloboquadrina dutertrei. Our record shows a cooler thermocline temperature during the LGM than the Holocene and brief cooling during ~7,000 yr BP. By comparing our EEP thermocline temperature record with the data from the Western Equatorial Pacific (WEP), we suggest an El Niño-like state during the LGM.

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