Sixty years ago, at the height of the Cold War, American military scientists made a major achievement. They extracted a mile-long slender cylinder of ancient ice from the center of the Greenland ice sheet — the first ice core ever drilled directly from the surface into bedrock.
For decades, most of the samples sat half-forgotten in warehouses. But today, it’s helping scientists reconstruct Earth’s climate history — and potentially peek into its future.
The findings are sobering. The sample shows that less than a million years ago, much of Greenland’s present-day ice sheet was completely ice-free. There was less climate-warming carbon dioxide in the atmosphere then than there is today.
This raises the question: if it happened before, will it happen again?
“If you think about the future, how humans are pumping carbon dioxide and methane into the atmosphere, it’s going to keep our climate warm for a long time,” said University of Vermont geologist Drew Christer. That’s what’s melting most of these ice sheets. Get too hot for too long, and it’ll melt.”
Christ is one of the scientists currently exploring the secrets of ancient ice samples. Specifically, he’s studying ancient Earth fragments and deposits at the very bottom of ice cores — the part where ice connects to bedrock.
He also made some startling discoveries. The sediment is full of well-preserved insects and plants that have been frozen in place for hundreds of thousands of years.
These small snippets of ancient life offer a rare glimpse into the environment of ice-free Greenland. Clues so far point to a tundra landscape, dotted with mosses and cold-climate plants, complete with buzzing midges—not unlike the ice-free regions on the edge of Greenland today.
Christ shared his latest discovery last week promotion meeting at the American Geophysical Union’s annual fall meeting in Chicago.
“This type of record is unique because there are only about six ice cores collected from Greenland, all the way to the bottom,” he told E&E News. “And only a few are covered by sediment at the bottom of the climate record. So that’s one of the only ways you can say directly that this place in Greenland is ice-free.”
It’s a discovery that’s been waiting decades to be discovered — and likely never happened at all.
The ice core itself is a product of a strange period in U.S. military history. It was drilled from a site known as Camp Century – a military research center built directly into the ice of western Greenland.
Camp Century was one of several US military bases established in Greenland during the heightened Cold War tensions of the 1950s and 1960s. At the time, Greenland was seen as a point of defensive superiority between the United States and the Soviet Union, and it also became home to several radar stations designed to provide early warning of any potential nuclear attack.
The Century Camp, built in 1960, was officially designated as a scientific research station. According to its official purpose, it was supposed to study the feasibility of living in harsh polar conditions by building a small city deep in the ice. The camp has underground dormitories, kitchens and other day-to-day facilities connected by more than 20 tunnels dug into the ice and powered by nuclear reactors.
But the camp has another purpose.
Documents released by the Danish government show that the U.S. military is also carrying out a secret project called the “Ice Worm Project”-planning to build a network of nuclear missile launch sites under the ice. The project was not successful, mainly because of the dangerous and unstable conditions under the ice.
Camp Century was abandoned in 1966. Shortly thereafter, it collapsed rapidly beneath a changing wall of ice.
But its scientific legacy lives on. The Camp Century ice core has survived and has been used by researchers for scientific research over the years.
Even so, the sediments at the bottom of the core were ignored for decades. In the 1990s, parts of the sediment and core were shipped to Denmark and stored, mostly out of sight and out of mind.
It wasn’t until a few years ago that scientists rediscovered neglected deposits in jars in storage refrigerators.
This is the start of a new wave of interest in forgotten samples.
“We had a meeting of scientists who were interested in analyzing these types of materials from the bottom of the ice sheet and figuring out what we could do with them,” Chris said.
Christ was a postdoctoral researcher at the University of Vermont at the time. His lab was able to obtain several small sediment samples—just a few inches scraped from the top and bottom of a 12-foot sediment core.
Even these tiny samples yield enormous insights.
Trapped in the ancient soil are the remains of long-dead plants. Some samples may be as old as 2 million years. Others have less than a million.
The vegetation is the first sign that this corner of the ice sheet was once a very different landscape.
Chris added that this part of Greenland has historically been one of its cooler regions. That means it will take a long time to melt, and a significant amount of the ice sheet could be lost in the process.
Researchers published Their preliminary findings were published last year in a scientific journal.
Since then, they’ve been analyzing samples from the rest of the sedimentary core — all the middle parts they’d previously missed. What they found exceeded all expectations, Christ said.
“As a scientist, you’re just worried that it’s not going to be as successful as you think it is,” he said. “I was like, ‘There won’t be plants in this.'”
But when he sat in front of the microscope, he said, he was surprised to find that each sample contained ancient plants.
That’s exciting enough. But then the team noticed something else. As they screened the samples under the microscope, they noticed that “we’d see things that wobbled differently,” Chris said.
Upon closer examination, they realized they were seeing fragments of insects—evidence of animal life in ancient landscapes.
The more they look, the more they discover. The head of a midge larva swims into view. Then they saw a midge chrysalis whose wings had developed but were not yet ready to fly.
“We were looking and only saw little eyes looking up,” Christ said. “Then we found a whole beetle larva. All these little spines and these little legs and eyes — it was amazing.”
The team is still dating the new material, so they can’t date it yet. But Christ estimates it may be 400,000 years old.
This period of time falls within periods of Earth’s history known as interglacials — relatively warm periods between ice ages. At that time, Earth’s carbon dioxide levels were hovering below 300 parts per million—more than 100 parts per million lower than today’s levels.
As far as interglacials go, it wasn’t the warmest. But it also lasted about 30,000 years — long enough to melt most of the world’s iciest place.
Christ likened it to opening a cooler full of ice on a cool day. As long as the temperature is above freezing, the ice will eventually melt if the cooler is left on all day.
Things are a little different today. Carbon dioxide levels are higher and climbing rapidly. Some studies suggest that global temperatures are rising at the fastest rate in millions of years.
Meanwhile, the Greenland ice sheet is losing about 250 billion metric tons of ice each year.
That doesn’t mean the ice sheet is in imminent danger of losing all its ice. Scientists are still figuring out how quickly the ice sheet will melt under future warming, a process that could take thousands of years.
In the near future, though, ice sheets are expected to make a significant contribution to global sea level rise. a recent study found it was now inevitable that at least 3.3 percent of Greenland would eventually melt, adding nearly a foot to the rising water level of the ocean.
What happens to the ice sheets may depend on how quickly the planet continues to warm in the future. And that depends on the decisions the countries of the world make today to tackle climate change.
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