Idaho State University scientists reported on Apr. 1 that shifts in the Atlantic Ocean’s currents influenced Alaska’s climate roughly 13,000 years ago, according to a new paper published in Nature Communications. Bruce Finney, professor at ISU, collaborated with Lesleigh Anderson of the United States Geological Survey and W. Brad Baxter, an Idaho State alum, to investigate how these oceanic changes led to cooler winters in Alaska during that period.
The findings are significant because they connect events in the North Atlantic—such as disruptions of the Gulf Stream due to freshwater from melting glaciers—to climate changes far away in Alaska. The team analyzed sediment cores from three Alaskan lakes and compared them with ice cores from Greenland to trace environmental conditions over time.
“In the Atlantic, off the east coast of the United States, the Gulf Stream flows north, delivering a lot of heat to northern latitudes,” said Finney. “This northward flow can be interrupted if a lot of freshwater is dumped into the North Atlantic in areas around Greenland. As glaciers melted at the end of the last ice age, a lot of freshwater was discharged into this region, halting the flow of heat northward. This caused a well-known climate reversal back to glacial-like conditions that affected the North Atlantic region, including Scandinavia and Europe, for about 1,000 years.”
By examining oxygen isotope ratios in both lake sediments and glacier ice cores, researchers found similar decreases occurring at about the same time period—evidence that supports their theory about interconnected climatic events between oceans and continents centuries ago.
“Because previous strong evidence for this event in this region was lacking, we did not expect to see it,” said Finney. “We determined that the climate cooling was mainly in winter, which explains why most records in Alaska hadn’t found it as they studied things like pollen which don’t tell us much about winter.” Baxter added: “Comparing different climate proxies and their distinct expressions of climatic events was intriguing… It gave us multiple perspectives on the story.”
The research group continues its work by analyzing additional lake cores across Alaska for further verification. Looking ahead at modern concerns over changing ocean currents’ effects on global climates—including regions such as Idaho—Finney said: “The new data from Alaska gives insight into how such changes might affect the other side of the globe.”
