took samples from deep beneath the island's ice sheet.

This frozen time capsule was forgotten for decades, until it was accidentally unearthed from a storage freezer.

Now, researchers are using these samples to gain insights into Greenland's climate history

and to get a clearer picture of its future as Earth's climate warms.

"We finally picked this plateau. A smooth, white plane of ice for as far as you can see."

Back in 1959, the U.S. army created Project Iceworm to hide hundreds of nuclear missiles

under the ice of northwestern Greenland. Their cover story?

Project Iceworm was just a polar science station named 'Camp Century!'

The base had twenty-one tunnels, a movie theater, hot showers, a chapel, chemistry labs,

enough room for 200 residents, and the world's first portable nuclear reactor.

Project Iceworm, and Camp Century, were eventually abandoned due to a heady mix of political disagreement and unstable ice conditions.

But since Camp Century was, after all, a polar science station,

researchers had already done some important work before the whole operation shut down.

Although they may not have realized it at the time.

In 1966, the team dug nearly 1400 meters down into the ice sheet.

When they finally hit dirt, they took a few cookie jars worth of samples before stopping.

Those samples were labeled, preserved in a freezer, and subsequently forgotten.

Fast forward half a century later, when after their accidental rediscovery,

scientists began investigating them for the first time.

And what they found was stunning.

Not only did the samples contain sand and rock, but they also contained the fossilized remains of plant material!

Let me emphasize that again, these are perfectly preserved plants!

Unlike bones or teeth, soft plant tissues are usually destroyed before they become fossilized.

You need really specific conditions and a little bit of luck, to preserve them.

Past studies have suggested that Greenland was free of ice more than a million years ago.

But these Camp Century samples contained perfectly preserved fossilized plants, which throws that entire timeline into question.

Ice sheets tend to destroy what's in their path, and since plant tissue is especially delicate,

this means Greenland may have been ice-free much more recently than we previously thought.

To help figure out this timeline, the team first looked at an oxygen isotope within the pores of the sediment.

After running tests on the isotope, they hypothesized that precipitation must have fallen at much lower elevations than the ice sheet's current height

which means the ice sheet that we know today wasn't there at the time.

Next, the scientists looked at the radioactive isotopes of aluminum and beryllium.

These two isotopes form in minerals that are on Earth's surface, left exposed to the Sun's cosmic rays.

While the aluminum isotope forms seven times faster than beryllium, it decays twice as fast once cut off from Earth's surface

in this case, by the ice.

By comparing the degradation rate of these two isotopes, the team was able to figure out

how long all of that plant material in the ice core samples was on Earth's surface

and how long it had been buried for.

And their findings have some pretty scary implications.

They estimate that the soil and plant remains could be from over a million years ago, or as recent as 400,000 years ago.

This may spell trouble. A Greenland that's melted off in recent geological history is a sensitive Greenland.

That said, by knowing the history of Greenland's ice sheet, we can better predict the consequences of our intensifying climate crisis.

Greenland's ice sheet is about three times the size of Texas, and if it all melts, the seas would rise by as much as seven meters.

That's as tall as a two story building, enough to flood coastal cities all around the world,

from New York to London to Dhaka.

And according to NASA observations, Greenland has been steadily losing ice for the past 30 years.

If this trend continues, we will be on course for the “worst-case” scenario of sea level rise.

The best part of these studies is that they can help us understand what Earth's climate may be like in the future,

which can then help us make decisions about how to prepare and act.

Who would have thought that a Cold War military base would lead to an international collaboration to fight a common enemy: the climate crisis?

To learn more about the mysterious Camp Century, check out this Focal Point episode here.

Make sure to subscribe to Seeker and thanks for watching. I'll see you next time.