Somewhere deep within a Greenland glacier lie the remains of Camp Century, a short-lived experiment in Cold War warfare. In 1959, the U.S. military began building a network of tunnels dug into the ice, hoping to turn them into launch sites for nuclear missiles.
By 1967, the military had abandoned the idea and the base. But samples of ice and frozen sediment that scientists extracted from the depths of Camp Century continue to provide new insights into the history of the planet.
When Paul Bierman, a geologist at the University of Vermont, began studying some of these samples, he made a surprising discovery. Scientists believed that the Greenland ice sheet had been stable for the past 2.6 million years. But what Dr. Bierman and his colleagues saw under a microscope provided clear evidence that parts of the ice sheet had temporarily melted much more recently. About 400,000 years ago, the site was ice-free.
Dr. Bierman spoke to The New York Times about this discovery, which he recounts in his new book, “When the Ice Is Gone.” This conversation has been condensed and edited for clarity.
We wouldn’t have these samples if it weren’t for Camp Century. What was the Army doing in Greenland?
It started in World War II. Greenland is upwind of the European theater of operations, so to make weather forecasts, they needed boots on the ground in Greenland. It was also the shortest route to get planes from the U.S. to the Allies.
The United States settled in Greenland and realized that they did not know much about the science of cold regions. The men who were stationed there did not have the proper sleds, they could not move across the ice safely, they did not understand how ice and snow behaved.
So the U.S. military started investing a lot of money in the ice. They built several camps under the ice and started drilling a deep ice core at Camp Century. When they got to the bottom of the ice sheet, they went ahead and pulled out almost 12 feet of what we call sub-ice material, which is frozen soil and water. It was a first.
After a couple of years of drilling out that core and looking at just the clear ice part, they discovered more than 100,000 years of climate history. But they ignored the bottom sediment. In 2019, they gave us samples of that bottom material. And that’s when things got really fun.
In your book, you say that these samples gave rise to the only real eureka moment of your scientific career. Tell me about it.
The samples arrived on a hot July afternoon in a DHL box with lots of frozen packages. We could smell the incredible smell of diesel fuel, because in the 1960s they used a mixture of diesel fuel and trichloroethylene (dry cleaning fluid) to keep the hole in the ice open while they were drilling.
We were sifting through these samples, which involved trying to sort them by grain size. So we took out the pebbles, the sand, and the silt. Everyone was hot and tired, and I was staring absentmindedly at the bucket of water with the sandy fraction. Suddenly, I saw some little black specks floating on top and was startled. I looked at the two people with me and said, “I think we have fossil plants here.”
I grabbed a pipette and squeezed out these little black specks. Drew Christ, who was a postdoc with me, put them under the microscope. And there was about 10 seconds of deathly silence before he poked his head out with a string of cheerful expletives.
We were observing plants growing where the ice cap is today. When the three of us stopped chattering, we quickly realized that this was probably the greatest discovery we had ever made in our scientific lives.
From then on, we continued to find fossils: fungi, insect parts, small pieces of wood, leaves, moss, a poppy seed. It’s amazing.
What was so impressive?
It makes your stomach turn to see a poppy seed where today there are miles of ice. It’s the kind of evidence that everyone understands: Today it’s ice, and yesterday it was plants.
It wasn’t long before we had one of those moments that day of, “Wow, this is cool, and wow, this is scary.” Because this was all before we started changing the climate. So, now we know that Greenland can melt on its own – and what are we doing? We’re giving it a big kick in the butt to melt even faster.
But humans were clever enough to figure out, in the 1950s, how the ice sheet worked, how to live on it, and how to drill an ice core. I don’t think saving the Greenland ice sheet is impossible. I think it will take the same determination.
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