Paleoceanographic studies have shown that early Pliocene warm period (~3.0 to 4.5 million years ago) was characterized by a permanent El Niño-like mean state. However, it is unclear how high frequency climate variability (e.g., the El Niño Southern Oscillation, or ENSO) was different (if at all), and more generally, how ENSO was impacted by changes in the mean state of the climate system. Questions remain about potential biases in the data, and little is known about high frequency tropical Pacific climate variability during the early Pliocene warm period.
This accomplishment-based renewal aims to address these outstanding issues by building on over fifteen years of prior research by the lead investigator, a professor at the University of California at Santa Cruz. Her pioneering work has established much of what is known about the Pliocene, the most recent period in Earth's history when when the average global temperature was higher than today for a sustained period of time. This two part study will include 1) synthesis and review of existing records of early Pliocene variability on different time scales, and 2) generation of new paired Mg/Ca-d18O analyses on single foraminifer shells in order to evaluate within-sample variability thought to be related to high frequency ENSO variability.
The principal investigator has trained a generation of students in the techniques and questions framing this research. A graduate student will also be involved in this research and synthesis. A significant part of the proposed work will be a workshop on tropical Pacific climate variability during times of global warmth, especially significant because the Pliocene warm period is thought to be a potential analog for future climate.
