B33: Characterizing Indian Summer Monsoon hydroclimate over the last 3,000 years using leaf wax biomarkers in lacustrine sediments
Presenter(s)
Sam Schultz
Faculty research mentor
Bronwen Konecky
Poster/exhibit session
11:30AM - 12:30PM: Poster session B
Acknowledgments
Office of Undergraduate Research, NSF-EAR P4CLIMATE Award 2303255, A David and Lucile Packard Foundation Fellowship in Science and Engineering to B. Konecky
Abstract or Description
The Indian Summer Monsoon (ISM) provides rainfall to billions of people on the Indian subcontinent. Understanding the evolution of ISM hydroclimate during recent geologic time is critical to evaluating its response to current and future global changes. Currently, there are few terrestrial paleoclimate records that exclusively capture past ISM variability without competing signals from the East Asian Summer Monsoon (EASM). Plant leaf waxes preserved in sediment cores recently collected from Loktak Lake, Manipur (24⸰N 93⸰W) provide valuable means to reconstruct past ISM changes without interference from the EASM. Here, we show the first results of a leaf wax n-alkane hydrogen (δ2Hwax) and carbon (δ13Cwax) isotope record extending back roughly 3,000 years at centennial-scale resolution. The δ2Hwax record primarily conveys changes in regional precipitation driven by ISM intensity. The δ13Cwax record is expected to capture changes in the surrounding vegetation community linked to shifts regional effective moisture. Characteristics of n-alkanes, such as average chain length (ACL) accompany isotope data. These reveal changes in the source of n-alkanes preserved in Loktak Lake, which also reveal past hydroclimatic and environmental changes. The ISM is expected to respond significantly to global forcings occurring during the last 3,000 years, such as those during the Little Ice Age. Our leaf wax n-alkane records will augment previous speleothem and marine records in helping to better understand ISM dynamics.