Year

2015

Degree Name

BEnviSci Hons

Department

School of Earth & Environmental Science

Advisor(s)

Helen McGregor

Abstract

The coupled oceanic-atmospheric convective system in the tropical Pacific Ocean, known as the El Niño Southern Oscillation (ENSO), is one of the most significant climatological phenomena on the globe. Due to the relatively short length of time covered by instrumental records over the equatorial Pacific Ocean, the variation of this phenomenon through time has been difficult to evaluate. By characterising past climate variability we gain insight into how ENSO behaved under different climatic regimes, and this provides predictive power to forecasting future climate. The implementation of proxy climate records can provide valuable windows into past climate variability and extends our current understanding of such phenomena. This study presents a 46-year long fossil coral Sr/Ca reconstruction of past sea surface temperature (SST) from Kiritimati Island (2ºN 157ºW) in the central equatorial Pacific Ocean during the 15th century. The fossil coral record shows slightly cooler SST’s during this time period and an 18% reduction in ENSO variability compared to modern climate. This is consistent with other paleoclimate records from around the Pacific Ocean that also show a reduction in ENSO variability during this time period. The results of this study, along with other studies from around the Pacific, indicate that the increase in ENSO variability in recent times may be an indication of increasing El Niño strength under a warming climate.

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