The real mission was to build a top-secret missile base. But, in the early 1960s, the U.S. Army publicly trumpeted the creation of a scientific station called Camp Century—a “city under the ice” they called it, in northwestern Greenland, far north of the Arctic Circle. A series of twenty-one horizontal tunnels spidering through the snow—complete with movie theater, portable nuclear reactor, nearly two hundred residents, hot showers, a chapel, and chemistry labs—all, they said, in aid of research.
As part of the effort, a team led by U.S. glacier scientist Chester Langway drilled a 4,560-foot-deep vertical core down through the ice. Each section of ice that came up was packaged and stored, frozen. When the drill finally hit dirt, the scientists worked it down for twelve more feet through mud and rock. Then they stopped.
For decades, this bottom-most layer of ice and rock from the core was lost in the bottom of a freezer in Denmark. Last year, it was rediscovered—in some cookie jars.
Last week, more than thirty scientists from around the world gathered at the University of Vermont for four days to decide what this one-of-a-kind sample of silty ice and frozen sediment might tell us—and how best to study it.
UVM geologist Paul Bierman, who led the workshop, thinks it may be “the key, the Rosetta Stone,” he said, to understanding how durable the ice on Greenland was during past warmings and coolings. And this, in turn, can give scientists a much clearer sense of how fast Greenland might melt in the warming world of the future. Since some twenty feet of sea-level rise is bound up in that vast ice sheet, the answer to this question is of dramatic global consequence.
The preliminary results that Bierman and two scientists in his lab—Drew Christ and Lee Corbett—presented at the workshop are troubling. “We should be hoping that this dirt has been covered for two or three million years or more,” he said. Instead, the team’s analysis of the sediment, with support from the National Science Foundation, suggests the massive ice sheet over Greenland must have been greatly reduced within the past million years or less—during a warm time when the Earth’s climate was similar to today.
“This is tentative. We did most of this work in just the last few days, going like mad to be ready for the workshop,” Bierman said, “but, if this first look holds true, this is big-time bad news.” A Greenland that melted off recently, when the past was like today, is a Greenland that is likely to quickly melt again.
Worming in the ice
To recreate the Camp Century ice core now would cost tens of millions of dollars. To understand how the bottom few yards of it was lost—the rediscovery of which attracted scientists from France, Denmark, China, Belgium, Canada, and ten U.S. universities to come to UVM to discuss—requires a trip back to the Cold War.
All the scientific effort at Camp Century was cover for the super-secretive Project Iceworm. Even the Danish government that controlled Greenland didn’t know that the camp’s actual purpose was to build a system of tunnels more than 2,000 miles long to hide 600 nuclear missiles under the ice close to the Soviet Union.
Project Iceworm failed. The vast ice sheet, thought to be an unmovable mass, was shifting and flowing much faster than expected. The tunnels were deforming and a rapidly accumulating overburden of snow threatened to make them collapse. Camp Century was abandoned by 1967.
But the ice core lived on. Initially, it was shipped to an Army laboratory in New Hampshire. Then, in the early 1970s, it was moved to a freezer at the University at Buffalo where Chester Langway was a professor. There, he and others studied its many layers. The temperature record they extracted from this ice helped re-write our understanding of the ancient past, how climates could shift, ice ages come and go.
“With all the scientific focus on the ice,” said Bierman—a professor in both UVM’s Geology Department and Rubenstein School of Environment and Natural Resources, and also a fellow in the Gund Institute for Environment—“the mud and rock that Langway’s team brought up from the frozen depths were forgotten.” And by 1993, the Camp Century core itself had been mostly forgotten, pushed aside by the excitement over two other even-deeper ice cores—GISP2 and GRIP—that drilled down two miles in the center of Greenland.
“Chet Langway was so fed up,” recalled Jørgen Peder Steffensen who traveled from Denmark to attend the UVM workshop and is professor and curator of the ice core repository at University of Copenhagen. No scientists were writing to him to request samples from the Camp Century core or seemed interested in what its ice might reveal. “He said, ‘you come over here and get the ice,’” Steffensen recalled, “otherwise it goes into Lake Erie.” Soon, crates and shipping containers full of ice, including the Camp Century cores, were on their way back across the Atlantic to Denmark.
Technicians in Copenhagen repacked and relabeled the boxes of ice from Langway. Among the thousands of containers, “some were oddly labeled ‘Camp Century sub-ice,’” Steffensen said. "I never thought about what was in those two boxes.”
From the cookie jar
Then, at the end of last year, he and Dorthe Dahl-Jensen, an esteemed glaciologist at the University of Copenhagen, were going through the extensive collections of ice cores—from Antarctica, Greenland and other places—stored at the university, preparing them for a move to a new freezer.
Steffensen again spotted the strange “sub-ice” boxes—and opened them up. They were full of glass jars. “Well, when you see a lot of cookie jars, you think: who the hell put this in here? No, I didn't know what to make of it. But once we got it out, we picked it up to see these dirty lumps, and I said: what is this now?” Steffensen said. “And all of a sudden it dawned on us: Oh s--t, this is the sediment underneath it. The ‘sub-ice’ is because it's below the ice. Whoa.”
They knew that what was an overlooked bit of dirt collected in the 1960s was a treasure for scientists with modern techniques for dating the last exposure of sediment. So they contacted Paul Bierman at UVM and Joerg Schaefer at Columbia University—both experts on new techniques for measuring the ages of ancient landscapes. They soon were on a plane to see for themselves what was in the Danes’ freezer.
This summer, with less than two pounds of material—a sample from the top and the bottom of the whole twelve-foot column —Bierman, Christ and Corbett set to work in UVM’s Community Cosmogenic Facility, an NSF-supported public laboratory. When they looked under the microscope they were amazed. Instead of just rock and sand, they saw bits of moss and wood. This meant that the ice at Camp Century was probably frozen in place on top of soil and hadn’t scraped off feet of bedrock like many moving glaciers and ice sheets do.
Bierman is an expert at analyzing tiny amounts of radioactive isotopes that form in quartz when soil and rock is exposed to the sky, bombarded by cosmic rays. The longer the exposure, the more isotopes form. In quartz, aluminum-26 forms seven times faster than beryllium-10—and it decays twice as fast. The ratio between the aluminum and beryllium isotopes serves as a kind of clock to let the scientists measure how long it has been since a landscape was not covered with ice.
But these isotope data can be hard to interpret because it’s not necessarily clear that the material being tested is from the top-most layer of land; a glacier could scrape away many feet of soil and rock. But having organic matter—probably remnants from a time when Greenland was covered with forest—gave them confidence that they could put a limit on the maximum time the dirt had been buried under ice.
The UVM scientists knew they had a treasure, and soon Christ was shipping out bits of it to other scientists around the world. These colleagues went hunting for oxygen isotopes to measure temperature; electrons that reveal when the samples were last exposed to sunlight; plant waxes, freeze-dried plants, the age and chemistry of rock chips and sand grains in the long-frozen soil—and a host of other clues about how long ago the land under Camp Century was last ice-free and what the climate and landscape was like.
At the end of October, all the scientists (plus one reporter from Science Magazine) came to Vermont to talk about the first modern data gathered from the core collected there more than half a century ago, and what else they could learn from its bottom stretch of soil and rock. Over posters and technical talks—and with support from UVM’s geology department, Gund Institute for Environment, College of Arts and Sciences, the offices of the provost and the vice president for research, as well as Columbia University, “plus lots and lots of coffee,” Bierman said—they pondered what it might mean.
The UVM team’s data, compiled literally the evening before the workshop began, fell in line with results from the one other deep core to ever reach the bedrock of Greenland, GISP2. Both indicate that the ice where they were drilled can’t be older than one million years. Another scientist, Tammy Rittenour, geologist at Utah State University, Skyped into the workshop to report brand-new luminescence data from the material Drew Christ had sent her. It suggested Camp Century may have been ice-free as recently as 400,000 years ago.
For most of the Earth’s history, the planet has been free of ice. During these long greenhouse periods, tropical forests sometimes extended north, even close to the North Pole, and the oceans were hundreds of feet higher than today. Paul Bierman and the many scientists gathered at UVM would like to avoid this happening again in the coming centuries—and to find out what a unique sample of mud in old cookie jars can show about what it took in the past to melt the ice on Greenland and cover it with trees.