Research Symposium

BIO

My name is Sydney Garber and I am a Junior at Florida State University, studying Environmental Science. I'm from Tallahassee, Florida. I am planning to continue working with Dr. Atwood’s research lab through my undergrad. I am enjoying learning more about working in a geochemistry lab, and pursuing my research goals. After graduation, I plan to attend graduate school and continue research in a Master’s program. I am fascinated by the ocean, so in my free time I frequent the beach as much as possible!

Mid-Holocene Climate Reconstructions from Kiritimati Coral Records

Abstract

Paleoclimatology is the study of the climate system before direct measurements were available. We analyze oxygen isotopes and trace elements in coral aragonite to learn more about past climate variability. The oxygen isotope composition (18Ocoral) of the aragonite reflects the sea surface temperature (SST) and salinity of the surrounding ocean water as the coral grows. The corals we analyze are from Kiritimati Island, which is located in the central equatorial Pacific (1.87ºN, 157.43ºW). To obtain these 18O measurements, we slab the coral along the maximum growth axis and then drill along this line using a high resolution or bulk sampling technique. High resolution sampling requires drilling the coral millimeter by millimeter along the growth transect, while bulk sampling consists of drilling the growth transect in one continuous sweep. The high resolution data allows us to track seasonal and year-to-year changes, while bulk data only allows us to estimate mean changes.
Both methods show lower 18O values, indicating that the area was overall cooler and drier in the mid-Holocene (around 4,000 to 7,000 years ago). Compared to the high resolution records, the bulk records from the mid-Holocene show less coral-to-coral variability. It’s currently unknown whether this reduced variability in the bulk records reflects a true climate signal or whether it is due to secondary alteration of the aragonite. We are producing more high resolution data to fully resolve this discrepancy and reconstruct climate variability during the mid-Holocene. This data is important for contextualizing modern climate variations.

Keywords: Geochemistry, Coral, Oxygen Isotope