Sixty years ago, at the height of the Cold War, US military scientists accomplished a great feat. They extracted a mile-long, slender cylinder of ancient ice from the heart of the Greenland ice sheet – the first ice core ever drilled from the surface straight down to bedrock.
For decades, a large part of the sample lay half-forgotten in storage. But today it’s helping scientists reconstruct Earth’s climate history — and possibly glimpse into its future.
The results are sobering. The sample suggests that less than a million years ago, much of what is now the Greenland ice sheet was completely ice-free. And there was less climate-warming carbon dioxide in the atmosphere then than there is now.
This begs the question: if it has happened before, can it happen again?
“If you think about the future, how humans put carbon dioxide and methane into the atmosphere, it’s going to keep our climate warm for a very long time,” said Drew Christ, a geologist at the University of Vermont. “And that could melt away large parts of these ice sheets. It’s too warm for too long and it’s melting.”
Christ is one of the scientists currently investigating the mysteries of the ancient ice sample. In particular, he studies the bits of old earth and sediment at the very bottom of the ice core — the part where the ice connects to bedrock.
And he’s made some stunning discoveries. The sediment is filled with perfectly preserved insects and plants that have been frozen in place for hundreds of thousands of years.
These small fragments of ancient life offer a rare glimpse into the environment of an iceless Greenland. The evidence so far points to a tundra landscape dotted with mosses and cold-climate plants and teeming with mosquitoes—not unlike the ice-free zones on the fringes of Greenland today.
Christ shared the latest findings in a presentation at the American Geophysical Union’s annual fall meeting in Chicago last week.
“This type of record is unique because there are only about six ice cores from Greenland that reach the bottom,” he said in an interview with E&E News. “And only a few of them are covered with sediments at the end of the climate record. And that’s one of the few ways to say directly that there was no ice at that spot in Greenland.”
It’s a discovery that’s been waiting for decades to be unearthed — and might not have happened in the first place.
The ice core itself is the product of a strange period in US military history. It was drilled from a site known as Camp Century – a military research center built directly into the ice in western Greenland.
Camp Century was one of several US military bases established in Greenland during rising Cold War tensions in the 1950s and 1960s. At the time, Greenland was considered a defensive vantage point between the United States and the Soviet Union, and it also became the site of several radar stations designed to provide early warning of possible nuclear attacks.
Camp Century, completed in 1960, was officially designated as a scientific research station. Among its official purposes, it was to study the feasibility of life in harsh polar conditions by building a small city deep within the ice itself. The camp was complete with underground dormitories, kitchens and other facilities of daily life, connected by more than 20 tunnels carved into the ice and powered by nuclear reactors.
But the camp had another purpose.
Documents released by the Danish government have revealed that the US military was simultaneously working on a secret initiative known as Project Iceworm – plans for a network of nuclear missile launch sites to be built 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. After that, it quickly collapsed under the moving ice walls.
But his scientific legacy lived on. Camp Century’s ice core survived and has been used by researchers in scientific studies over the years.
Even so, the sediments at the very bottom of the core have been overlooked for decades. And in the 1990s, the sediments and parts of the core itself were shipped to Denmark and stored, mostly out of sight and out of sight.
Just a few years ago, scientists discovered the neglected sediments lying in jars in the freezer.
That was the beginning of a new interest in the forgotten rehearsals.
“We had a meeting with scientists who were interested in analyzing these types of materials from the bottom of the ice sheet and figuring out what we can do with them,” Christ said.
Christ was a postdoctoral fellow at the University of Vermont at the time. His lab was able to take several small samples of the sediments — just inches from the top and bottom of the 12-foot sediment core.
Even these tiny samples provided great insights.
Enclosed in the ancient earth were the surviving remains of long-dead plants. Some of the samples were probably as old as 2 million years. Others were less than a million.
These bits of vegetation were the first indication that this corner of the ice sheet was once a dramatically different landscape.
This part of Greenland has historically been among the colder areas, Christ added. That means it would have taken a long time to melt away, and likely a significant portion of the ice sheet would have disappeared in the process.
The researchers published their first results last year in a specialist journal.
Since then, they’ve analyzed samples from the rest of the sediment core — all the middle sections that they previously missed. And their discoveries have exceeded all expectations, Christ said.
“As a scientist, you’re just worried that things won’t go the way you imagined,” he said. “I was like, ‘There won’t be any plants in there.'”
But when he sat down at the microscope, he said he was amazed to find that every sample contained ancient plants.
That was exciting enough. But then the team noticed something else. As they viewed the samples under the microscope, they noticed that “we would see things that wobbled differently,” Christ said.
Upon closer inspection, they found they were looking at fragments of insects – evidence of animal life in the ancient landscape.
The longer they searched, the more they found. The head of a mosquito larva swam into view. Then they saw a mosquito pupa with wings developed but not yet ready to fly.
“We look and only see the little eye peeking up,” Christ said. “Then we found a fully intact beetle larva. All those little spikes and those little legs and eyes—amazing.”
The team is still in the process of dating the new footage, so they can’t say for sure how old it is just yet. But Christ estimates it’s probably 400,000 years old.
This period fell into an era in Earth’s history known as the interglacial period – a relatively warm period between ice ages. At that time, the Earth’s carbon dioxide concentration was mostly below 300 parts per million – more than 100 parts per million lower than today.
As for interglacials, it wasn’t the warmest. But it also dragged on for about 30,000 years—long enough to melt significant swaths of the world’s iciest places.
Christ compared it to opening a cooler filled with ice on a chilly day. As long as the temperatures are above freezing, the ice will eventually melt if the cooler is left open all day.
Today’s conditions are a bit different. Carbon dioxide concentrations are higher and still increasing rapidly. Some research suggests that global temperatures are rising at the fastest rate in millions of years.
Meanwhile, the Greenland ice sheet is losing around 250 billion tons of ice every year.
That doesn’t mean the ice sheet is in imminent danger of losing all of its ice. Scientists are still studying how quickly the ice sheet could melt under future warming scenarios, a process that could take thousands of years.
In the near future, however, the ice sheet is expected to contribute significantly to global sea level rise. A recent study found that it is now inevitable that at least 3.3 percent of Greenland will eventually melt, raising sea levels by nearly a foot.
What happens to the ice sheet will likely depend on how quickly the planet continues to warm in the future. And that depends on the choices the world’s nations are making today to address climate change.
E&E News reprinted with permission from POLITICO, LLC. Copyright 2022. E&E News provides important news for energy and environmental professionals.