A new documentary is shedding light on a remarkable period in Earth’s history—one when large parts of Greenland, now buried under thick ice, were open land touched by sunlight and air.
The film, The Memory of Darkness, Light and Ice, explores how scientists uncovered evidence that some regions of northwest Greenland were ice-free around 400,000 years ago.
This discovery helps researchers better understand how Earth’s climate has changed over long stretches of time and what it may look like in the future.
The documentary follows a team of international scientists as they study ice and sediment samples that were originally collected in the 1960s but forgotten for decades.
These samples came from Camp Century, a Cold War–era U.S. military base built beneath the ice in northwest Greenland.
From 1959 to 1967, the base served both military and scientific purposes. During that time, researchers drilled more than 1,000 meters through the entire ice sheet to reach the soil below—soil that now serves as a key to understanding Greenland’s ancient past.
Director Kathy Kasic, a former evolutionary biologist, traveled to research labs around the world to film scientists analyzing these historic samples.
She visited the University of Washington, where professor Eric Steig, one of the featured researchers, helped lead the scientific effort to re-examine the old material.
Steig explains that the project started when researchers at the University of Vermont formed a plan to analyze the rediscovered samples.
He invited Kasic to document the process as it unfolded. Her early involvement meant she could capture the real-time excitement and challenges of piecing together a picture of Greenland’s past climate.
In Steig’s lab, researchers focused on isotopes—different versions of elements like oxygen, hydrogen, carbon and nitrogen found in tiny pockets of preserved water and ancient soil.
The ratios of these isotopes reveal important details: how temperatures changed, what kinds of plants once grew there and how ecosystems shifted over time.
Working together with European scientists analyzing the ice layers just above the soil, the team built a clearer understanding of what happened when the ice sheet melted in the distant past.
So far, the research confirms that during a long warm period about 400,000 years ago, parts of Greenland were ice-free.
Although the climate may not have been dramatically hotter than today, it stayed warm for a very long time—long enough to melt major sections of the ice sheet. These results match climate model predictions and offer a real-world reference point for understanding what could happen as modern temperatures continue to rise.
Steig says the samples collected in 1960 are now incredibly valuable because drilling new holes through the ice sheet is expensive and technically challenging.
Only a few successful drilling projects have ever reached the sediment beneath Greenland’s ice, making these historical samples rare and essential.
The film highlights a major shift in climate science. For decades, researchers focused on understanding ice ages—times when Earth was much colder.
Now, as the Greenland Ice Sheet melts and sea levels rise, scientists are urgently studying past warm periods instead. The documentary shows how looking back in time can help us prepare for the future, offering a deeper understanding of what a world with much less ice may look like.
