USU Lab Contributes to New Documentary on Findings Beneath Greenland Ice Sheet

The idea of anything being preserved beneath a mile of glacial ice seems like something out of a science-fiction movie. But a new documentary, The Memory of Darkness, Light, and Ice, chronicles not just how scientists in the 1960s discovered evidence of a time when there was life where the Greenland Ice Sheet is now, but also how researchers today are using new technologies to understand what those findings mean for our planet’s future. And at the heart of that undertaking is the Utah State University Luminescence Lab.

During the Cold War, the documentary explains, the United States saw Greenland as a strategic asset in a future war against the Soviet Union. The U.S. Army established Camp Century, billed as “the city under the ice,” just below the surface of the ice sheet in 1959. While the military cited scientific research as the facility’s primary purpose, there was another mission: to test the viability of housing nuclear warheads in the Greenland Ice Sheet. The goal of the operation, codenamed Project Iceworm, was to create a military base that could easily reach the Soviet Union and potentially survive a nuclear first strike.

The ice proved too unstable, and Camp Century was ultimately abandoned in 1967. However, prior to its closure, scientists and engineers drilled the first-ever core through an ice sheet and retrieved a 1.3-kilometer-long record of the ice. It contributed greatly to researchers’ understanding of the climate, and the sediment at the bottom of the core included an intriguing mix of trace plant and insect remains, hinting at a time when Greenland wasn’t covered in an ice sheet.

But while researchers at the time were able to study things like the chemical composition and stratigraphy of the ice, they couldn’t date the sediment itself, meaning they couldn’t be sure when this warmer period had occurred. The core moved from the University of Buffalo in New York to the University of Copenhagen in Denmark, where it sat at the back of a freezer for decades, waiting for a time when new technologies could unlock its secrets.

That time came in 2019, when a scientist saw the core listed in the Niels Bohr Institute’s ice core storage facility in Copenhagen. They reached out to USU Geosciences Professor Tammy Rittenour at the Luminescence Lab to use a technique called luminescence dating, which can date when sand was last exposed to sunlight.

All soils emit a very low level of ionizing radiation, according to Rittenour, and even tiny amounts of quartz or feldspar absorb that radiation, with negatively charged electrons from the radiation gathering in defects in the crystal due to their slightly positive charge.

“It’s the same process as charging a battery,” she said. “The electrons are stored in the crystalline structure, and as long as the quartz or feldspar isn’t exposed to light or heat, they remain there and accumulate over time. In the lab, we can stimulate them to luminescence, which is just those electrons being removed from the crystal and releasing light in the process. The number of trapped electrons is proportional to how long the material has been buried and in turn the amount of light released as a luminescence signal.”

Because their samples would lose the electrons they accumulated if exposed to light — “bleached” is the term used by scientists — the Luminescence Lab takes great pains to avoid white light. An opaque revolving door blocks out the rest of the world, while the orange overhead lights that illuminate the lab distort color, making red objects appear black The computers in the lab have their power lights taped over, and they can only be turned on after samples are stowed away. Even with a filter applied to the monitor, a small white square appears onscreen at boot up, and that’s enough to cause bleaching.

Much of Rittenour and the Luminescence Lab’s work ties into the Earth’s climate, with project topics spanning from how the dry lakes in Antarctica might have responded during past warming intervals to the history of Lake Bonneville, the large body of water that once covered much of Utah.

But because of the versatility of luminescent dating, she and the lab have been involved in a wide variety of projects. In one case, they worked with the Laguna Pueblo in New Mexico to prove they had been using water in the area before European settlers arrived and secure their water rights; in another, they assessed the stability of the landscape around a Dominican Republic gold mine to see if expansion was viable.

The lab also supports archaeologists in dating artifacts and sites of human activity, such as when one of Rittenour’s students dated a large, 500-year-old bison jump in Wyoming.

In the case of Camp Century, the sediment from the ice core proved to be much older than just five centuries, yet surprisingly recent nonetheless. A parallel team of scientists had already used other methods to determine that base of the sediment record had to be less than 3 million years old, while the upper part was less than a million years old. After Rittenour carefully extracted sediment grains from a domino-sized piece of frozen sediment and completed the monthslong analysis, however, the date came back at a mere 400,000 years old.

“That sounds super old to most people, but it’s actually quite young to a geologist and much younger than when the Greenland Ice Sheet first formed,” Rittenour said. “Over the last million years, the planet has swung between colder and warmer glacial and interglacial periods as a result of variations in the Earth’s orbit around the sun, and we’ve known there was an exceptionally warm interglacial more recently that might have led to melting in Greenland. Now we know that 400,000 years ago, it was warm enough to at least melt this one section of the ice.”

Rittenour and other scientists are still working out how much of the ice melted. But a more troubling question raised by the findings is what might happen to Greenland today. While there was already evidence in the ’60s of rising carbon dioxide levels and subsequent warming due to human activity, the scale of the situation wasn’t as well understood.

For instance, when Camp Century was abandoned, most of the facility and all the chemical, nuclear and biological waste housed within it were left behind under the assumption that they would stay safely frozen for millennia. Yet judging by how the ice melted 400,000 years ago after a slower, natural warming period, that assumption is increasingly unlikely to hold up in today’s world, when greenhouse gases introduced by people are accelerating rapid warming. And that’s going to cause problems, Rittenour said.

“The movie touches on all of this,” she said in reference to The Memory of Darkness, Light, and Ice, “but if you melt substantial parts of the Greenland Ice Sheet, sea levels will rise, and it impacts communities across the globe. If the ice sheet is gone, you also lose this big, white reflector of solar radiation, and that means the Earth is absorbing more energy, which speeds up warming even faster. We have satellite images that show this has been occurring for decades, and not just in Greenland, because the same thing is happening to the West Antarctic Ice Sheet.”

While Rittenour was excited by the findings of the lab, she also acknowledged that they were sobering.

“We as a species evolved under climate conditions of the last glaciation,” she said. “And while we’re smart and can maybe adapt with technology, we’re also dependent on a web of ecosystems and Earth systems that support our food, air and water resources. Atmospheric carbon dioxide levels are over 100 parts per million higher today than at any time in the last million years, and it will take thousands of years for it to naturally get out of the system. Given the link between carbon dioxide and climate change, it’s a wakeup call.”

The Memory of Darkness, Light, and Ice released for streaming in October on Amazon Prime, iTunes, Fandango, YouTube, Vimeo, and cable tv (Xfinity, Comcast and Armstrong).