The Past is the Key to the Present: Reconstructing Changes in Seasonal Precipitation Triggered by Ancient Climate Change

• Main Author: Ward, William
• Format: Text
• Language: English
• Published: Western CEDAR 2020
• Subjects: Plant biomarkers; Paleoclimates; Climate change; Geology; Ocean acidification
• Online Access: https://cedar.wwu.edu/scholwk/2020/2020/56; https://cedar.wwu.edu/context/scholwk/article/1673/viewcontent/Ward_Past_is_Key_to_the_Present_SW2020_Bo_Ward.pdf

Plant biomarkers have grown in use for defining paleoclimates in the geologic record, especially during major climate change events. Research utilizing these biomarkers often looks at leaf waxes within preserved organic matter in the rock record. These waxes are resilient to decomposition and thus are invaluable to paleoclimate reconstruction. Specifically, changes in the composition of hydrogen isotopes (D/H) in leaf wax lipids (n-alkanes and fatty acids) reflect changes in precipitation and can be used to model variability in the hydrologic cycle during major climate change events, such as abrupt global warming events (e.g. hyperthermals). The Paleocene-Eocene Thermal Maximum (PETM), about 56 Mya, was the largest of these hyperthermals and is characterized by global warming, ocean acidification and poor organic matter preservation. It is thought that these changes had a global impact on the hydrologic cycle. Despite successful uses of biomarkers in paleoclimate research, biomarker analyses during the PETM have so far been unsuccessful. This study applies new methods of bulk sampling to isolate n-alkanes from PETM rocks and measure changes in hydrogen isotopes during this global warming event. Our research aims to answer outstanding questions concerning how climate change affects seasonal rainfall in the continental interiors. Given the PETM event is often used and analog for anthropogenic climate change, our results can improve our understanding of future climate scenarios.