Lapworth Lecture - Unlocking the Secrets of Vietnam’s Past Climate: Insights from Stalagmites

Stalagmites in Vietnamese caves preserve tens of thousands of years of monsoon history, but cave processes can modify the climate signal. They grow over long periods, can be dated by uranium-thorium methods, and can preserve geochemical records of rainfall, temperature and vegetation. Rainwater is filtered through soil and bedrock before it reaches the cave, and the cave atmosphere changes seasonally. Without understanding these processes, climate signals may be misinterpreted.

Central Vietnam is a good place to examine this. The Northeast and Southwest Monsoons, which draw moisture from different oceans, alternate seasonally over mainland Southeast Asia, and the Trường Sơn mountains influence how each reaches the caves. Records from this region may help show how both monsoon systems responded to major climate changes, provided the cave processes are understood first.

More than rainfall can now be investigated in a single stalagmite. Temperature can be estimated from microbial membrane lipids (TEX₈₆), and vegetation changes traced using lignin-derived compounds, alongside oxygen and carbon isotopes. However, these measurements do not always respond together, and cave conditions can bias what each one records. This raises a key question: how confidently can past climate be reconstructed from a stalagmite?

This lecture has two parts. The first uses six years of monitoring of atmosphere and drip water in Soong Cave to show how outside weather and the movement of water through the rock influence what the cave records. The second applies this understanding to a stalagmite from Soong Cave spanning the last deglaciation, roughly 34,000 to 10,000 years ago, to examine how temperature, vegetation and monsoon rainfall changed as the climate warmed.

About Chloe

Dr Chloe Riviera is a cave scientist, explorer and palaeoclimatologist. She completed her PhD in Earth and Environmental Sciences at Northumbria University, where her work focused on reconstructing past changes in the Asian monsoon from Vietnamese stalagmites. Her research combines long-term cave monitoring with geochemical records from stalagmites in Vietnam.

The lecture is free and open to all, and is available to watch in-person on campus or on Zoom.