Reconstructing past sea surface temperatures near the Iceland-Faroe Ridge using alkenone paleothermometry (Uk’37 )

• Main Author: Mellon, Stefanie
• Format: Report
• Language: unknown
• Published: 2019
• Subjects: Greenland; Greenland ice core; Greenland Ice core Project; ice core; Iceland
• Online Access: http://hdl.handle.net/10222/76545

ENVS 4902 Environmental Science Undergraduate Honours Thesis Understanding the ocean and its past behaviour is important because it gives insight into rates and amplitudes of global change. This thesis uses a paleoceanographic technique (Simplified Ketone Unsaturation Index (Uk’37)) that reconstructs sea surface temperatures (SST) of the past ocean in deep-sea sediment cores. SST is an important parameter because it is the temperature of the interface between oceanic and atmospheric heat reservoirs. The study site is located southeast of Iceland, which is of particular interest to oceanographers because it is a key region of deep-water formation. These data can be used to test the reliability of general circulation models (GCM). If GCMs can accurately simulate conditions of the past, then we can have more confidence in the models’ predictions of future climate change. Results of the study show two warm periods in the past that were both warmer than present day SSTs, and that the amplitude between warm and cold periods was 9 ±1.5°C. The exact age of the observed trends cannot be determined due to a lack of radiocarbon dating, therefore three potential age models are discussed in this thesis, based on lightness data of the core and the Northern Greenland Ice Core Project δ18O record. Assuming that these age models are correct, we can conclude that the late Holocene (present day) was cooler than the early Holocene (11,700 years BP), and that the Last Glacial Maximum was warmer than present day SST values, based on Uk’37 paleothermometry. The causes and implications of these findings will be discussed in the context of the literature. It is suggested that further research take place using another proxy measure and more sediment cores in order to better illustrate the past climate of this region.