Geology & Environmental Science Colloquium: Laura Lopera Congote | GES PhD Candidate, University of Pittsburgh

South American Summer Monsoon variability and water balance from the Lake Junín (Central Peruvian Andes) molecular isotopic record over glacial-interglacial timescales Presented by Laura Lopera Congote | GES PhD Candidate, University of Pittsburgh Talk Abstract: We are experiencing a period of rapid climate change driven by fossil fuel use, leading to unprecedented environmental change. I aim to understand the climate variability of the Andes and Amazon basin to better constrain future climate change scenarios. While meteorological records rarely extend beyond the past 100 years, we can use lake sediment records to expand our knowledge of how climate has changed over much longer timescales (700,000 years in the case of Lake Junin). Over the past 2.6 million years, the Earth’s climate has oscillated between cold periods (glacials) and warm periods (interglacials). Yet, most paleoclimate records focus on the Holocene (~12,000 years BP), but much less is known beyond this time, because reliable paleorecords of climate extending that far back into time are scarce, especially in tropical South America. However, long sediment cores from Lake Junin in the central Peruvian Andes, offer the opportunity to reconstruct climate, (i.e. temperature, precipitation, and water stress) over several glacial interglacial cycles, providing an unprecedented perspective on tropical climate change. In this sense, studying previous interglacial periods where controls on climate, such as greenhouse gas concentrations are different, is a powerful tool for understanding the drivers and consequences of climate change. Here, I present a paleoclimate record from the Central Peruvian Andes over the past ~22,000 years. Using molecular fossils (biomarkers), I aim to reconstruct South American Summer Monsoon intensity, water stress as a response to monsoon dynamics (water balance), and changes in temperature. The hydrogen (δ2H) and carbon (δ13C) isotopic composition of sedimentary plant waxes