It’s relatively common knowledge that ice cores provide insights into past climates. But researchers at the Environmental Physics Division of the University of Bern have developed a way to get similar information by extracting water from stalagmites and analyzing its hydrogen and oxygen isotopic composition.

The hydrogen and oxygen isotopic composition of rainfall is influenced by a variety of climatic factors, including air temperature, and the amount and origin of precipitation. Changes in this composition can be used to reconstruct past temperature patterns. Speleothems such as stalagmites, stalactites and flowstones are natural archives of paleo-precipitation since they’re formed by groundwater and rainfall. Speleothems contain very small amounts of water which is trapped in so-called fluid inclusions within and between the calcite crystals, similarly to gas bubbles in ice cores. Up until recently, measuring hydrogen and oxygen isotopes in fluid inclusions simultaneously was difficult, time consuming and therefore did not allow developing continuous and highly resolved isotope records.

In this blog, researchers at the Climate and Environmental Physics Division of the University of Bern, explain how they developed a new method to extract microliter amounts of water from stalagmites. And, also how they analyze the hydrogen and oxygen isotopic composition using a Picarro L2140-i water isotope analyzer. Through this method they were able to address the Holocene temperature conundrum, an important issue in the paleoclimate community.