Ralls reported in late April 2025 that Greenland’s ice-covered landscape looks like an immovable block on satellite maps. Yet the story locked beneath its center suggests a very different past, one that places future coastal cities in a tight spot.
Willow bud scale, arctic poppy seed, fungal bodies, and rock spikemoss megaspores
found in the GISP2 soil sample viewed under a microscope at the University of Vermont.
Credit: Halley Mastro/University of Vermont
During the Pleistocene – the geologic chapter that began about 2.7 million years ago and ran through innumerable swings between cold and mild – the island’s ice waxed and waned in tune with global climate. New evidence hints that those swings were more dramatic than scientists once believed. In 1993, drillers hauled a two‑mile‑deep ice core up from the island’s highest point and stowed the entire column in a Colorado freezer. The surprise awaited in the bottom three inches of sediment: perfectly preserved traces of a tundra ecosystem. That sliver of soil, shielded for ages by roughly 1.9 miles (3 km) of ice, now refocuses the conversation about future sea level and the stability of polar ice in a warming world.
Tundra hidden beneath Greenland’s ice
Once the drill broke through that 1.9‑mile roof of ice, the researchers retrieved those three inches of till.
“These fossils are beautiful,” says Paul Bierman, a scientist at the University of Vermont who co‑led the new study with UVM graduate student Halley Mastro and nine other researchers.
“But, yes, we go from bad to worse,” Bierman added, referring to what this finding implies about the impact of human‑caused climate change on melting of the Greenland ice sheet.
The till holds poppy, spike‑moss, woody willow tissue, fungal sclerotia, insect parts, and a band of soil capped by about 16 inches of erratic boulders. This is clear evidence that central Greenland once lay ice‑free under a cold, dry sky where late‑lying snow lingered through early summer. Because the material sits undisturbed, the team is confident it was not swept in from elsewhere as ice advanced.
Inside a deep Greenland ice core
“Once we made the discovery at Camp Century, we thought, ‘Hey, what’s at the bottom of GISP2?’” Bierman recalled.
High‑energy isotope ratios show that the summit last saw open air within the past 1.1 million years, while argon trapped in overlying clear ice indicates at least 250,000 years of continuous cover since then. Basal ice at another drilling site about 19 miles away is roughly 1 million years old. A separate core from Camp Century near the coast yielded plant remains no older than 416,000 years, underscoring the ice sheet’s flickering presence across the Pleistocene. These findings draw on material that had been stored at the National Science Foundation Ice Core Facility in Lakewood, Colorado, for three decades.
Fossils divulge a warmer Greenland
Under the microscope, what had looked like no more than specks floating on the surface of the melted core sample was, in fact, a window into a tundra landscape.
“It was amazing,” Mastro exclaimed.
Mastro and colleagues picked out spores of spike‑moss, the bud scale of a young willow, and the compound eye of an insect – life‑forms adapted to chilly air and long summer daylight.
“And then we found Arctic poppy – just one seed of it. That is a tiny flower that’s really good at adapting to the cold. It lets us know that Greenland’s ice melted and there was soil, because poppies don’t grow on top of miles of ice,” Mastro continued.
Sea‑level risks for global coasts
Sea level today is rising more than an inch each decade. “And it’s getting faster and faster,” said Bierman. The extra water comes from a warming ocean that expands as well as from melting glaciers worldwide. Near‑complete melting of Greenland’s ice over the next centuries to a few millennia would lead to some 23 feet of sea‑level rise.
“Look at Boston, New York, Miami, Mumbai, or any other coastal city around the world, and add 20‑plus feet of sea level. It goes underwater. Don’t buy a beach house,” Bierman advised.
Sea level is likely to be several feet higher by the end of this century, when today’s children are grandparents.
Greenland’s fragile ice fortress
Richard Alley, a leading climate scientist at Penn State, reviewed the new research.
“This new study confirms, and expands upon earlier evidence, that significant sea‑level rise occurred at a time when the causes of warming were not especially extreme, providing a warning of the damage we might cause if we continue to warm the climate,” Alley noted.
“We now have direct evidence that not only was the ice gone, but that plants and insects were living there,” Bierman concluded. “And that’s unassailable. You don’t have to rely on calculations or models.”
The fossil soil at Greenland’s summit, locked beneath nearly two miles of ice, speaks plainly: polar ice sheets can retreat far and fast when the climate tips, and the coastlines of the future will trace that story in real time. Whether that warning is heeded remains a decision for policy makers and citizens alike.
The full study was published in the journal Proceedings of the National Academy of Sciences.
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