Department Seminar: Hai Cheng

Title: Speleothem: The fourth pillar of paleoclimate research

Abstract: Speleothems, secondary cave deposits of carbonates, encode a wealth of hydroclimatic information and have been extensively studied globally. In particular, over the past 25 years, speleothem-based paleoclimate research has achieved major advances in reconstructing Earth’s climate history across a broad range of spatial and temporal scales. As the field matures, the drive for new breakthroughs has intensified, giving rise to several emerging frontiers. This talk highlights three frontiers particularly. First, recent progress in carbonate U-Pb dating has extended the reach of speleothem archives to “deep time”, beyond the traditional U-Th limit of ~600,000 years. This has enabled investigations of global climate change throughout the Quaternary, including low-latitude perspectives on the Mid-Pleistocene Transition, etc. Second, the growing availability of high-resolution, precisely dated speleothem records now allows for the development of a comprehensive correlation framework across key components of the Earth system—a potential “Paleoclimate Rosetta Stone”. Of note is that it enables us to establish an important geochronological benchmark for potentially defining the beginning of a new epoch—the Upper Pleistocene GSSP (Global Boundary Stratotype Section and Point). Third, analyses of interdecadal variability and early warning signals preceding abrupt shifts (tipping) in these records offer new opportunities to understand dynamics of future climate change, illustrating the enduring relevance of the idea that “the past is one of the keys to the future”. These advances have positioned speleothems as a vital fourth pillar of paleoclimate science.