2017-2018 Schlanger Fellow – Sarah White

Sarah White

University of California, Santa Cruz

Constraining the effect of dissolution on Pliocene West Pacific Warm Pool SSTs and the “permanent El Nino-like state”

Abstract

Pliocene tropical sea-surface temperatures (SSTs) are hotly debated. Foraminiferal Mg/Ca records show no long-term trend in west Pacific warm pool (WPWP) SSTs, despite higher Pliocene pCO₂, and a reduced east-west SST gradient. However, modeling results and TEX86 records disagree with these findings. These discrepancies may stem from changes in dissolution (driven by Δ[CO₃^2-]), which biased the Mg/Ca records. I propose using benthic foraminiferal B/Ca, a proxy for Δ[CO₃^2-], to constrain the effect of dissolution on Pliocene Mg/Ca temperatures. This study would be the first to correct Mg/Ca data for time-varying dissolution. Validating Pliocene SSTs has broad significance; the WPWP is crucial for calculating climate sensitivity, and the east-west SST gradient affects climate variability.

Biography

Living in California, I have observed firsthand the importance of interannual climate variability, particularly El Nino-Southern Oscillation (ENSO). During my undergraduate studies at UC Santa Barbara, I worked in Jim Kennett’s lab, and fell in love with the big-picture insights that paleoceanography can give into the climate system. My master’s research with Tessa Hill at UC Davis, which focused on millennial-scale climate oscillations along the California margin, focused my interest in high-frequency climate shifts, and drove me to seek out the largest source of interannual climate variability: the tropical Pacific. Under the guidance of Christina Ravelo at UC Santa Cruz, I have developed my PhD research on the response of tropical Pacific climate variability and mean state to varying boundary conditions over the past five million years. My Schlanger Fellowship project, on Plio-Pleistocene tropical Pacific sea-surface temperatures, will help constrain climate sensitivity to pCO₂, and inform my concurrent work on Pliocene ENSO. Data generated for my Schlanger project will also have implications for deep ocean circulation, which I’m looking forward to learning more about.