Cave Stalagmites in Tropical Borneo Reveal Over 100,000 Years of Climate Events

Ice cores and temperature readings aren't the only ways to find out about climate change. Researchers have now used cave stalagmites collected from tropical Borneo to learn a little bit more about past climate events and how to potentially prepare for them in the future.

Today, relatively subtle changes in the tropical Pacific's ocean and atmosphere have profound effects on global climate. However, there are few records of past climate changes in this region that have the length, resolution and age controls needed to reveal the area's response to abrupt climate change events. That why the researchers turned to the stalagmites.

"Stalagmites are time capsules of climate signals from thousands of years in the past," said Stacy Carolin, a Georgia Tech Ph.D. candidate who gathered and analyzed the stalagmites, in a news release. "We have instrumental records of climate only for the past 100 years or so, and if we want to look deeper into the past, we have to find records like these that locked in climate signals we can extract today."

In order to actually glean information from these stalagmites, though, the researchers sawed each rock formation open like a hot dog bun. They then used tiny drill bits to take samples of the calcium carbonate at the center of the stalagmites. Since these rock formations grew at varying rates, each sample represented as little as 60 years of time or as much as 200 years. The researchers then determined the ages of the samples by measuring uranium and thorium isotope rates.

So what did these stalagmites tell the researchers? The new record that resulted from the samples seems to indicate that climate feedbacks within tropical regions may amplify and prolong abrupt climate change events that were first discovered in the North Atlantic. The researchers also found that climate responded to abrupt changes known as Heinrich events. Yet another major type of event, known as Dansgaard-Oeschger excursions, left no evidence in the stalagmites.

"To my knowledge, this is the first record that so clearly shows sensitivity to one set of major abrupt climate change events and not another," said Kim Cobb, an associate professor at the School of Earth and Atmospheric Sciences at the Georgia Institute of Technology, in a news release. "These two types of abrupt change events appear to have different degrees of tropical Pacific involvement, and because the tropical Pacific speaks with such a loud voice when it does speak, we think this is extremely important for understanding the mechanisms underlying these events."

The findings have helped show the past history of the Earth's climate. In addition, it shows how a particular region adapted to massive changes and could allow scientists to better predict climate shifts in the future.

The findings are published in the journal Science.