Scientist Finds Historical Precedent for Warm Water Melting Antarctic Ice Shelves

Dr. Minzoni samples sediment cores

Dr. Minzoni samples sediment cores

From the March 2017 Desktop News In the last few decades, oceanographers have recognized that warm currents running underneath modern ice shelves in Antarctica are compromising ice sheet stability and contributing to rising sea levels, but there has been little evidence of historical precedent, until now.

University of Alabama assistant professor Dr. Rebecca Totten Minzoni recently completed a study proving that the relatively warm Circumpolar Deep Water Current caused melting on the underside of ice shelves in the Amundsen Sea thousands of years ago.

“Plenty of people have made this assumption because we know Deep Water is present in these basins today,” Minzoni said. “But this is the first time we’ve been able to show it in the geological record.”

Minzoni did her research in Ferrero Bay studying the Cosgrove ice shelf, and using cores taken from the sea floor, she and her team were able to date when there had been an ice shelf in the area and when the ice shelf retreated or broke up.

Retrieving core samples from the ocean floor

Retrieving core samples from the ocean floor

The cores taken by Minzoni and her team captured the last 11,000 years of sedimentation on the continental shelf below where ice shelves used to sit. Through analyzing the color and size of the particles in the sediment, marine plankton, and seafloor dwelling organisms, Minzoni and her team were able to construct a record of oceanographic and glacial change in the area.

For example, by identifying algae in the core, Minzoni and her team can determine when the ice shelves broke apart. Similarly, by identifying the presence of sea floor foraminifera that are associated with warm water, they can determine when there were warm water currents in the past.

“As a paleoclimatologist, what worries me the most is how the loss of modern ice shelves and acceleration of continental glaciers will contribute to sea level,” Minzoni said. “This research of past changes may be key to evaluating the stability of these glacial systems and better estimating their contribution to sea level rise.”

Minzoni’s research will be published in Holocene, and has already gained the attention of one of the biggest earth sciences news periodicals Eos.