CAREER: Contextualizing recent extreme El Nino events over the late Holocene using trace element paleothermometry in tropical Pacific corals

This project will produce coral-based sea surface temperature reconstructions in the tropical Pacific Ocean. These records will document the El Niño-Southern Oscillation (ENSO) climate phenomenon during the last 3000-years. Today, ENSO drives changes in weather patterns around the globe every few years.

It originates in the tropical Pacific Ocean and atmosphere and can have severe and far-reaching impacts that affect the natural environment and the lives of billions of people. A series of extreme El Niño events over the last several decades suggests that rising atmospheric greenhouse gases may be causing ENSO events to intensify. However, how ENSO may change in a warmer world is not well known.

Advances in understanding ENSO are currently limited by the short duration of instrumental sea surface temperature records. Approaches that use paleoclimate proxy data provide a way to produce temperature estimates from before the instrumental era. However, those longer proxy temperature records rely on sparse networks of coral-based records.

This project will reduce that data gap by producing ~40 new decades-long coral-based temperature records from the central and eastern Pacific Ocean. The project’s education and outreach activities include efforts to recruit and retain undergraduates from groups underrepresented in the earth sciences and to strengthen active learning in the Florida State University undergraduate curriculum.

They also include development of cross-disciplinary graduate research opportunities and efforts to improve science literacy in northern Florida high schools. The project includes four years of graduate student support and support for undergraduate researchers each year.

The project will generate 40 new quantitative temperature records over the last 3,000-years from key regions of the equatorial Pacific Ocean spanning the eastern edge of the warm pool to the core of the cold tongue. An ensemble reconstruction approach will use smaller, more widely available coral archives than have traditionally been used in the past – coral rubble – and measurements will combine traditional Sr/Ca measurements with newer Sr-U techniques.

Rigorous screening tools for diagenesis, including microscale analyses, will be employed to extract reliable climate information from the fossil records. The reconstructions will provide unprecedented quantitative constraints on the evolution of equatorial Pacific sea surface temperatures on seasonal to millennial time scales, including characterizing whether and how the statistics of extreme ENSO events have changed since the industrial era, relative to the prior 3,000-years of Earth history.

The educational objectives of the project will increase the scope and impact of the research, while also addressing outstanding needs in geoscience education. These educational objectives focus on expanding professional development opportunities, skill building, and diversity and leadership training for graduate students and postdocs entering the scientific workforce.

The project will also integrate research with community needs and education at international field sites.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.