“We had always assumed that the Greenland ice sheet formed about two and a half million years ago-and has just been there this whole time and that it’s very stable,” says Tammy Rittenour, a scientist at Utah State University and co-author on the new study. The team’s new study in Science, combined with their earlier work, is causing a major and worrisome rethinking of the history of Greenland’s ice sheet. “Greenland’s past, preserved in 12 feet of frozen soil, suggests a warm, wet, and largely ice-free future for planet Earth,” says Bierman, a geoscientist in UVM’s Rubenstein School of the Environment and Natural Resources and a fellow in the Gund Institute for Environment, “unless we can dramatically lower the concentration of carbon dioxide in the atmosphere.” The new study provides strong and precise evidence that Greenland is more sensitive to climate change than previously understood-and at grave risk of irreversibly melting off. Since about twenty-three feet of sea-level rise is tied up in Greenland’s ice, every coastal region in the world is at risk. Understanding Greenland’s past is critical for predicting how its giant ice sheet will respond to climate warming in the future and how quickly it will melt.
He co-led the new study with lead author Drew Christ, a post-doctoral geoscientist who worked in Bierman’s lab Professor Tammy Rittenour from Utah State University UVM professor Nicholas Perdrial in the Department of Geography and Geosciences UVM research scientist Lee Corbett and sixteen other scientists from around the world. “It's really the first bulletproof evidence that much of the Greenland ice sheet vanished when it got warm,” says University of Vermont scientist Paul Bierman. This melting caused at least five feet of sea level rise around the globe. The new study presents direct evidence that sediment just beneath the ice sheet was deposited by flowing water in an ice-free environment during a moderate warming period called Marine Isotope Stage 11, from 424,000 to 374,000 years ago. Now, using advanced luminescence technology and rare isotope analysis, the team has created a starker picture: large portions of Greenland’s ice sheet melted much more recently than a million years ago. Other scientists, working in central Greenland, gathered data showing the ice there melted at least once in the last 1.1 million years-but until this study, no one knew exactly when the ice was gone. But, two years ago, using the rediscovered Camp Century ice core, this team of scientists showed that it likely melted less than one million years ago. Until recently, geologists believed that Greenland was a fortress of ice, mostly unmelted for millions of years. Their new study was published in the journal Science on July 21, 2023. It was accidentally rediscovered in 2017 and shown to hold not just sediment but also leaves and moss, remnants of an ice-free landscape, perhaps a boreal forest.īut how long ago were those plants growing-where today stands an ice sheet two miles thick and three times the size of Texas?Īn international team of scientists was amazed to discover that Greenland was a green land only 416,000 years ago (with an error margin of about 38,000 years). Then this icy sediment was lost in a freezer for decades. Army mission, at Camp Century in northwestern Greenland, drilled down through 4560 feet of ice on the frozen island-and then kept drilling to pull out a twelve-foot-long tube of soil and rock from below the ice.
This indicates that the ice sheet on Greenland may be more sensitive to human-caused climate change than previously understood-and will be vulnerable to irreversible, rapid melting in coming centuries.ĭuring the Cold War, a secret U.S. A large portion of Greenland was an ice-free tundra landscape-perhaps covered by trees and roaming woolly mammoths-in the recent geologic past, new UVM-led research shows.
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