Greenland Ice Sheet’s Recent Melting Unearthed by Hidden Cold War Military Project’s Ice Core

About 416,000 years ago, a significant part of Greenland transformed from an icy expanse to an ice-free tundra, possibly resembling the current Greenland landscape, reveals a recent study published in the journal Science. This research challenges the long-standing belief that the Greenland ice sheet had existed for a significant part of the past two and a half million years. Instead, the study suggests that a period of moderate warming between 424,000 and 374,000 years ago resulted in dramatic melting. This understanding implies that the Greenland ice sheet might be more sensitive to anthropogenic climate change than previously assumed, making it prone to swift and irreversible melting in the forthcoming centuries. Credit: Joshua Brown/UVM

The recovered ice core shows that a majority of Greenland bore a green landscape approximately 416,000 years ago.

Approximately 416,000 years ago, a substantial portion of Greenland was characterized by an ice-free tundra, possibly dotted with trees and inhabited by woolly mammoths, the new study in the journal Science reveals. The research, carried out by scientists from the University of Vermont (UVM), Utah State University, and fourteen other institutions, utilized sediment from an ice core retrieved from a covert U.S. Army base in the 1960s. This information, alongside advanced luminescence and isotope techniques, provided direct evidence of the duration and timing of the ice-free period.

The Unexpected Discovery: Greenland’s Green Past

During the Cold War, a covert U.S. Army mission at Camp Century in Northwestern Greenland drilled a 4560-feet deep hole into the ice and retrieved a twelve-foot-long tube of soil and rock from beneath the ice. This sediment, forgotten in a freezer for several decades, was rediscovered in 2017, revealing evidence of an ice-free landscape, potentially a boreal forest.

A team of international scientists was astounded to discover that the frozen island had a verdant landscape just 416,000 years ago (with a margin of error of approximately 38,000 years). Their novel study was published in the journal Science on July 21, 2023.

Robust Evidence of Melting

Previously, geologists held the view that Greenland had remained mostly frozen for millions of years. However, two years ago, using the rediscovered Camp Century ice core, this team of scientists presented evidence that the ice likely melted less than one million years ago. Today, thanks to advanced luminescence technology and rare isotope analysis, the team paints a more concerning picture: large parts of Greenland’s ice sheet melted much more recently than a million years ago. This new study provides solid evidence that sediments just beneath the ice sheet were deposited in an ice-free environment during a period of moderate warming known as Marine Isotope Stage 11, from 424,000 to 374,000 years ago. This melting was responsible for at least a five feet rise in sea levels globally.

A Matter of Global Concern

The new study provides compelling and precise evidence that Greenland’s ice sheet is more susceptible to climate change than previously assumed and is at serious risk of irreversible melting. “Greenland’s past, preserved in twelve feet of frozen soil, suggests a warm, wet, and largely ice-free future for planet Earth,” says UVM geoscientist Paul Bierman. “Unless we can dramatically lower the concentration of carbon dioxide in the atmosphere.”

Insight From the Dark

In Utah State University’s laboratory, the sediment from the Camp Century core was examined for its “luminescence signal”. The number of released electrons gives an indication of when these sediments last saw sunlight. Combining these powerful new data with insights from UVM’s lab, which studied quartz from the Camp Century core, the scientists determined that the sediment was exposed to the sky less than 14,000 years before it was deposited under the ice. This information helped to pinpoint when that part of Greenland must have been ice-free.

A Forgotten Treasure

Camp Century was a secret military base under the Greenland ice sheet in the 1960s, initially intended as a top-secret operation to conceal nuclear missiles near the Soviet Union under the guise of an Arctic science station. Although the missile mission failed, the science team conducted unprecedented research, including drilling an almost mile-deep ice core. This ice core was lost for decades until it was found again during a freezer relocation.

Sea Level Implications

The study shows that the region around Camp Century, which is situated 138 miles inland from the coast and only 800 miles from the North Pole, melted entirely and was covered with vegetation during Marine Isotope Stage 11. The team’s models show that during that period, the ice sheet melted enough to cause at least five feet, and perhaps as much as twenty feet, of sea-level rise. The research indicates that melting even a part of the Greenland ice sheet will cause a significant sea level rise, threatening coastal cities and low-lying areas globally.

Reference: “Deglaciation of northwestern Greenland during Marine Isotope Stage 11” by Andrew J. Christ, Tammy M. Rittenour, Paul R. Bierman, Benjamin A. Keisling, Paul C. Knutz, Tonny B. Thomsen, Nynke Keulen, Julie C. Fosdick, Sidney R. Hemming, Jean-Louis Tison, Pierre-Henri Blard, Jørgen P. Steffensen, Marc W. Caffee, Lee B. Corbett, Dorthe Dahl-Jensen, David P. Dethier, Alan J. Hidy, Nicolas Perdrial, Dorothy M. Peteet, Eric J. Steig and Elizabeth K. Thomas, 20 July 2023, Science.
DOI: 10.1126/science.ade4248

Frequently Asked Questions (FAQs) about Greenland Ice Melting

More about Greenland Ice Melting

• Greenland Ice Sheet Melt ‘Off the Charts’ Compared With Past Four Centuries
• Greenland’s Rapid Ice Loss Continues, Even in Winter
• Greenland’s Melting Ice Nears a ‘Tipping Point,’ Scientists Say
• Understanding Climate Change and Sea Level Rise
• Hidden History of Camp Century
• Luminescence Dating: Guidelines on Using Luminescence Dating in Archaeology