Scientists found frozen plant fossils, preserved under a mile of ice on Greenland. The discovery helps confirm a new and troubling understanding that the Greenland Ice Sheet has melted entirely during recent warm periods in Earth’s history — like the one we are now creating with human-caused climate change. The new study provides strong evidence that Greenland is more sensitive to climate change than previously understood — and at risk of irreversibly melting.
In 1966, US Army scientists drilled down through nearly a mile of ice in northwestern Greenland — and pulled up a fifteen-foot-long tube of dirt from the bottom. Then this frozen sediment was lost in a freezer for decades. It was accidentally rediscovered in 2017.
In 2019, University of Vermont scientist Andrew Christ looked at it through his microscope — and couldn’t believe what he was seeing: twigs and leaves instead of just sand and rock. That suggested that the ice was gone in the recent geologic past — and that a vegetated landscape, perhaps a boreal forest, stood where a mile-deep ice sheet as big as Alaska stands today.
Over the last year, Christ and an international team of scientists — led by Paul Bierman at UVM, Joerg Schaefer at Columbia University and Dorthe Dahl-Jensen at the University of Copenhagen — have studied these one-of-a-kind fossil plants and sediment from the bottom of Greenland. Their results show that most, or all, of Greenland must have been ice-free within the last million years, perhaps even the last few hundred-thousand years.
“Ice sheets typically pulverize and destroy everything in their path,” says Christ, “but what we discovered was delicate plant structures — perfectly preserved. They’re fossils, but they look like they died yesterday. It’s a time capsule of what used to live on Greenland that we wouldn’t be able to find anywhere else.”
The discovery helps confirm a new and troubling understanding that the Greenland ice has melted off entirely during recent warm periods in Earth’s history — periods like the one we are now creating with human-caused climate change.
Understanding the Greenland Ice Sheet in the past is critical for predicting how it will respond to climate warming in the future and how quickly it will melt. Since some twenty feet of sea-level rise is tied up in Greenland’s ice, every coastal city in the world is at risk. The new study provides the strongest evidence yet that Greenland is more fragile and sensitive to climate change than previously understood — and at grave risk of irreversibly melting off.