A groundbreaking study has provided the first direct evidence that not just the edges but the very center of Greenland’s ice sheet melted in the recent geological past, transforming the ice-covered island into a green, tundra landscape.
Researchers revisited sediment samples from a two-mile-deep ice core drilled at the center of Greenland in 1993. Stored in Colorado for 30 years, these samples surprisingly contained pristine willow wood, insect parts, fungi, and a poppy seed.
“These fossils are beautiful,” remarked Paul Bierman, a scientist at the University of Vermont and co-leader of the study along with UVM graduate student Halley Mastro and nine other researchers. “But, yes, we go from bad to worse,” Bierman added, emphasizing the grave implications of human-caused climate change on Greenland’s ice sheet.
Published in the Proceedings of the National Academy of Sciences on August 5th, the study confirms that Greenland’s ice melted during a warm period likely within the last million years. This finding suggests that the ice sheet is more fragile than previously thought.
If the central ice melted, most of Greenland’s ice likely melted too, probably for thousands of years, allowing soil to form and an ecosystem to thrive. “This new study confirms and extends that a lot of sea-level rise occurred at a time when causes of warming were not especially extreme,” said Richard Alley, a climate scientist at Penn State, highlighting the potential damages from ongoing climate warming.
Currently, sea levels are rising over an inch per decade, accelerating rapidly. Bierman warned that without significant reductions in greenhouse gas emissions, Greenland’s ice could nearly completely melt over the next centuries to millennia, causing a sea level rise of about 23 feet.
“Think of Boston, New York, Miami, Mumbai, or any coastal city,” said Bierman. “Add twenty-plus feet of sea level rise – it goes underwater. Don’t buy a beach house.”
In 2016, Joerg Schaefer from Columbia University and his team analyzed rock from the same 1993 ice core (GISP2), suggesting that Greenland’s ice sheet could be no more than 1.1 million years old and that it experienced extended ice-free periods during the Pleistocene. This challenged the long-standing belief that Greenland’s ice had been solid for millions of years.
Then, in 2019, Bierman and an international team examined another ice core from Camp Century near Greenland’s coast. They found twigs, seeds, and insect parts, indicating the ice melted within the last 416,000 years. This suggested the ice fortress had failed more recently than previously thought.
“Once we made the discovery at Camp Century, we wondered, ‘What’s at the bottom of GISP2?'” said Bierman. Despite extensive studies on the ice and rock, the 3 inches of till at the bottom remained unexamined. Bierman and his colleagues requested a sample from the National Science Foundation Ice Core Facility in Colorado.
This new study in PNAS, supported by the U.S. National Science Foundation, confirms the 2016 “fragile Greenland” hypothesis and deepens concerns by showing a tundra ecosystem once thrived where ice is now two miles deep.
“We now have direct evidence that not only was the ice gone, but that plants and insects were living there,” said Bierman. “And that’s unassailable. You don’t have to rely on calculations or models.”
The discovery of intact biological material in the ice core was first made by geoscientist Andrew Christ, a former PhD student at UVM. Halley Mastro then closely studied the material, identifying spores from spikemoss, willow bud scales, an insect’s compound eye, and an Arctic poppy seed.
“It’s amazing,” said Mastro. “Poppies don’t grow on top of miles of ice, indicating that Greenland’s ice melted and there was soil.”
This discovery provides important insights into Greenland’s past and a stark warning about the potential future impacts of climate change.
Related Article: NASA Reports Record-Breaking Global Temperatures
For Firsthand Information, Join the ScienceNaija channel on WhatsApp
