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Sunday, October 17, 2021

Blast from the past

From using solar energy to replace fossil fuels to using robots to perform everyday tasks, science looks often into the future to solve the world’s problems, but the past could also be a link to the future. UC Davis geophysicist Gary Acton and his collaborators are using centuries old fossil records to make predictions about tomorrow’s climate changes.

Acton spent two months on board the drilling vessel JOIDES Resolution collecting sedimentary deposits from deep below the ocean floor. This sedimentary record, if analyzed correctly, could contain thousands of centuries of climate records – giving scientists ample data to make more accurate predictions for our planet’s climatic future.

From Nov. 17 through Jan. 17, the JOIDES Resolution collected data as it toured the Mediterranean Sea through the Strait of Gibraltar, which connects the Mediterranean to the Atlantic Ocean.

“This area is especially important and unique in that it contains thick, rapidly deposited sedimentary rock layers,” Acton said at a recent seminar in the UC Davis geology department.

This arrangement has many different rock layers piled one on top of another, with the oldest on the bottom and newest on the top.

Rock layers are created by currents, which are a major contributor to climate changes. Each time the current changes, the rock layer will change. This phenomenon is analogous to a sand dune; each time the wind changes direction or force, it moves the sand around with it and creates distinctive patterns and layers. Thus, each rock layer represents a different climatic signal.

Taking samples from this unique and rare rock formation allows geophysicists and other scientists to obtain an accurate record of prehistoric climatic conditions and changes to our global climate that have occurred over the past 100 million years or more.

“Only a few places in the world have this type of rapid sedimentary build up,” Acton said. “They are virtual prehistoric observatories.”

The drilling vessel, JOIDES – Joint Oceanographic Institutes for Deep Earth Sampling – has the unique ability to core far into the bottom of the sea floor. JOIDES is equipped with 10 meter long steel tubes called core drills that jut out from the bottom of the vessel. Scientists use a pressure core sampling technique that allows them to stack these 10 meter long core drills, one on top of another, to collect sediment samples 30 meters down.

Then, by analyzing the difference in sediment layers, scientists are able to make inferences about the ancient climate record. For example, sea sediments often reveal how much ice existed during a certain time period and thus hint about past temperatures and weather patterns.

Acton explained that the importance of understanding this climatic sequence is that climate change happens in cyclic patterns.

“If we understand the patterns and cycles of climate change, we may be able to show how climate change affected evolution and how it will impact us in the future,” Acton said.

Now that Acton and his collaborators have such important records at their fingertips, they are currently summarizing their data to present to the National Science Foundation in the hopes they will fund further research.

This past cruise on the JOIDES Resolution was Acton’s 10th cruise. In the future, he plans to continue research on sedimentary deposits and ocean drilling expeditions. He said this research is one of the best ways to analyze the past and make predictions about the future.

He also admits he likes being out at sea and says that after scientists go on cruises they have one of two opinions: they thought it was fun but never want to go again, or they look for the next opportunity to go on another one.

“I’m definitely in the second group,” Acton said.

CLAIRE MALDARELLI can be reached at science@theaggie.org.

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