The discovery helps confirm that the Greenland Ice Sheet has melted entirely during recent warm periods in Earth's history similar to the one being created now with human-caused climate change. It also 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 there. This frozen sediment was lost in a freezer for decades and was accidentally rediscovered in 2017.
Understanding the Greenland Ice Sheet in the past is critical for predicting how it will respond to climate warming in the future, and how fast it will melt. Since around 20 ft of sea-level rise is tied up in Greenland's ice, and 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 risks irreversibly melting off.