The change back then—discovered through an incredible sample collection during the cold war era—is attributed to the extreme warming period. The warming, which occurred in the recent geologic history of the Earth, eventually swept out the entire ice cover, resulting in vegetation sprouting out from the land beneath.
“Our study shows that Greenland is much more sensitive to natural climate warming than we used to think—and we already know that humanity’s out-of-control warming of the planet hugely exceeds the natural rate,” says Andrew Christ, geologist, who led the research.
Messenger from Cold War in a cookie jar
In 1966, a team at Camp Century—a Cold War military base—dug the ice sheet and excavated samples from a 1.4-km depth to examine the sediments. Although the real mission—named Project IceWorm—was to bury about 600 nuclear missiles, the camp was projected as a polar science station mission. However, the mission was not successful, but the team did collect thousands of feet deep samples of ice cores that could shed light on the ancient history of Earth.
But, there was a plot twist! The collected core tube sample—packed in a cookie jar—was lost, as it travelled from one army freezer to another for decades. The sample was rediscovered in 2017 and landed in the hands of scientists at the University of Vermont in 2019—after a gap of nearly 53 years! Disregarded until then, the sample turned out to be the first-of-a-kind fossil plants excavated from the bottom of Greenland.
Studying half-a-century-old samples
When the international team of scientists investigated the sediments under the microscope, they stumbled upon the evidence of something very peculiar in nature. To their surprise, scientists found remnants of twigs and leaves instead of just sand and rock. The results show that Greenland once hosted moss, lichen, spruce and fir trees, that too within the last one million years!
The team conducted a study on rare isotopes of aluminium and beryllium to understand for how long the vegetation was there and it turns out that the plants grew in the ice-free ground for a long duration. “Ice sheets typically pulverize and destroy everything in their path, but what we discovered was delicate plant structures—perfectly preserved. They’re fossils, but they look like they died yesterday. It’s a time capsule of what used to live on Greenland that we wouldn’t be able to find anywhere else,” says Christ.
Moreover, the radiocarbon and luminescence dating examination helped to find the exact time, which stated that melting took place within the last million years. Over the Earth’s history, the climatic conditions varied a lot, from ice ages to warmer interglacial periods. And Greenland’s sensitive environment seems to have reacted drastically to these changes.
What was Greenland like?
Among academicians, there have been continuous debates on what exactly Greenland’s ecosystem was like before the last interglacial warm period, which ended about 120,000 years ago. As per the official statement from the University of Vermont, this research is crucial evidence of ancient plant material that once thrived in northwestern Greenland. Their findings highlight that Greenland was ice-free within the last million years due to Earth’s warming.
Today Greenland’s 80% landmass is covered with ice sheets, however, it may face similar trends of greening again due to increased warming. Understanding the pattern of past melt-off can help scientists predict what the future holds for the white continent. It is estimated that the melt-off of Greenland’s ice can result in an increase of twenty feet of sea-level, which would inundate almost every coastal city on the globe.
“This is not a twenty-generation problem. This is an urgent problem for the next 50 years,” says Paul Bierman, a geoscientist at the University of Vermont, who led the study along with Andrew Christ.
The new research will be published in the journal Proceedings of the National Academy of Sciences on March 30 and can be accessed here.