A VU Inside: Professor explores caves for clues to climate change


by Amy Wolf

It’s not your normal trip to the lab. For Vanderbilt Assistant Professor of Earth and Environmental Sciences Jessica Oster, getting data means getting dirty. Oster and her team are collecting mineral deposits deep inside caves to find clues to climate change.

“The potential is there to look at climate change over the last half million years, Oster said. “The thing I love the most is that we’re answering what we think are really cool questions about how climate changes on land. The caving is just a bonus to that.”

Oster is a member of a small group of earth scientists pioneering the use of mineral cave deposits in stalagmites, collectively known as speleothems, as proxies for the prehistoric climate.

“We are interested in understanding carbon and how carbon is transformed as it moves from the soil into the cave,” said Oster.

Blue Spring Cave

Oster’s latest research is in the Blue Spring Cave in Middle Tennessee. At least once a month the team, along with Vanderbilt undergraduates, samples rain water and drip water in the cave and takes measurements of the cave air to understand how the chemistry of that water is changing as it moves from the surface into the cave.

“We can look at how the water chemistry changes through time. But if we’re going to understand that we really need to have a good idea of the modern system in the cave. So what we’re doing at Blue Spring is trying to develop that understanding of the modern system,” said Oster. “We can look at times when things were getting much warmer. We can look at times of rapid climate transitions.”

Data through drips

It turns out that the steady dripping of water deep underground can reveal a surprising amount of information about the constantly changing cycles of heat and cold, precipitation and drought in the turbulent atmosphere above.

As water seeps down through the ground it picks up minerals, most commonly calcium carbonate. When this mineral-rich water drips into caves, it leaves mineral deposits behind that form layers which grow during wet periods and form dusty skins when the water dries up.

“These drips over thousands and thousands of years will precipitate a little bit of this mineral and that’s how they form. In that process, starting out as rain and seeping through the soil and the limestone it’s also picking up different chemical signatures of the environment,” said Oster.

Those signatures become crystalized.

“And that’s what we analyze when we look at these climate records,” said Oster.

Oster has done research in numerous caves around the United States and the world.

Read more about Oster’s research »