Department Seminar: Nadia Sae-Lim

Title: Unraveling Tropical Monsoon Variability: Case Studies from the Andes and Southeast Asia

Abstract: Tropical monsoons are critical to the water security of billions, yet their variability on long timescales remains elusive. This seminar presents two case studies that combine paleoclimate proxies with climate models to illuminate the complexities of monsoon dynamics and their consequences for regional rainfall and hydrological balance. The first case, based on high-elevation lakes in the Peruvian Andes, leverages leaf-wax isotopes and microbial glycerol dialkyl glycerol tetraethers (GDGTs) to reconstruct South American summer monsoon variability throughout the Common Era, shedding light on precipitation-evaporation patterns and glacial changes in the highlands. The second case, focused on Mainland Southeast Asia, employs a proxy-isotope-enabled data assimilation framework that integrates speleothem archives with climate model ensembles to unravel hydroclimate variability over the last millennium. Together, these studies demonstrate how Pacific and Indian Ocean variability shape regional hydroclimate and underscore a broader objective: building comparative perspectives on tropical monsoons across the Pacific basin to inform our understanding of long-term climate-society interactions.