Scientists stunned to discover fossil plants under deep Greenland ice

In the 1960s, US Army scientists dug nearly a kilometer of ice in northwest Greenland and extracted a tube of soil from the bottom.

Chester “Chet” Langway, who joined UB’s geology faculty in the 1970s, was one of the leaders of the drilling expedition, at a site known as Camp Century. The samples his team collected there, including the frozen sediments, followed him to western New York. Materials resided here for several years before moving to Copenhagen, Denmark. Then the dirt was largely forgotten.

But in 2019, University of Vermont scientist Andrew Christ examined the sediment through his microscope – and couldn’t believe what he was seeing: twigs and leaves instead of just sand and rock. This suggested that the region had been ice-free in the recent geological past – and that a vegetated landscape lay where a mile-deep ice cap as large as Alaska stands today.

Over the past year, Christ and an international team of scientists – including Elizabeth Thomas, an assistant professor of geology in UB’s College of Arts and Sciences – have studied these unique fossil plants and sediments from the bottom of Greenland. In addition to Christ, the research was led by Paul Bierman from the University of Vermont, Joerg Schaefer from Columbia University and Dorthe Dahl-Jensen from the University of Copenhagen.

“Our study examines in detail the sediments beneath the Camp Century drill site in the northwestern part of the Greenland Ice Sheet. Our results suggest that at some point in the last million years, the Camp Century site was free of ice,” says Thomas, who performed chemical analyzes that helped the team understand the types of plants that were on the site.

“Ice caps usually pulverize and destroy everything in their path,” says Christ, “but what we discovered were delicate plant structures – perfectly preserved. They are fossils, but they look like they died yesterday. It’s a time capsule of what once lived in Greenland.

The research was published March 15 in the Proceedings of the National Academy of Sciences. (PNAS).

The discovery helps confirm a new and disturbing understanding that the Greenland Ice Sheet melted almost completely during recent warm periods in Earth’s history. For example, in 2016, a study in Nature led by Schaefer and co-authored by UB geology professor Jason Briner estimated that a sample of bedrock beneath the Greenland Ice Sheet was exposed to the open sky. for at least 280,000 of the last 1.4 million years.

Understanding the Greenland Ice Sheet in the past is key to predicting how it will respond to global warming in the future and how quickly it will melt.

The material for the new PNAS study comes from Camp Century, a Cold War military base dug inside the ice sheet high above the Arctic Circle in the 1960s. The camp was the site of an effort secret, called Project Iceworm, to hide nuclear missiles under ice. As a cover, the army presented the camp as a polar science station.

The military mission failed, but the science team did important research, including drilling an ice core 4,560 feet deep.

The new study clearly indicates that the deep ice at Camp Century has melted entirely at least once in the past million years and that the landscape was instead covered in vegetation, including moss and possibly shrubs.

The team of scientists used a series of advanced analytical techniques to probe the sediments, fossils and waxy leaf coating found at the bottom of the Camp Century ice core.

The new study shows that not all ecosystems of the past have been erased into oblivion by the bulldozing ages of glaciers and ice caps. Instead, the history of these living landscapes remains captured under the relatively young ice that has formed above ground, frozen in place, and holds them still.