The discovery of fossils in Greenland surprises scientists and confirms that the ice core has recently melted

Greenland’s story keeps getting greener—and scarier. A new study provides the first direct evidence that the center—not just the edges—of the Greenland ice sheet melted in the geological past and that the now-ice-covered island was home to green, tundra.

A team of scientists re-examined a few inches of sediment from the bottom of a two-kilometer-deep ice core taken from central Greenland in 1993—and held for 30 years in a Colorado reserve . They were amazed to find soil with willow wood, insect parts, fungi and poppy seeds in pristine condition.

“These traces are good,” says Paul Bierman, a University of Vermont scientist who led the new study with UVM graduate student Halley Mastro and nine other researchers, “but, yes, we’re going from bad to worse.” of the worst,” in what this means about the impact of human-caused climate change on the melting of the Greenland ice sheet.

Study, published in Bulletin of the National Academy of Sciences on August 5th, confirms that the Greenland ice sheet melted and the island became green during the pre-warm period perhaps within the last million years – suggesting that the great ice of ice breaks down more easily than scientists realized until a few years ago.

If the ice that covered the center of the island melted, most of the rest would have to melt as well. “And maybe for thousands of years,” Bierman said, enough time for the soil to form and for the ecosystem to take root.

“This new study confirms and expands that the sea level rise occurred during a time when the causes of global warming were less severe,” said Richard Alley, a senior climatologist at Penn State. who reviewed the new research, “providing a warning. what damage we can cause if we continue to warm the climate.”

Sea levels today are rising more than an inch per decade. “And it’s growing rapidly,” Bierman said.

It is likely to be several meters tall by the end of this century, when today’s children are grandparents. And if emissions of greenhouse gases—from burning fossil fuels—are not reduced significantly, he said, the complete melting of the Greenland ice sheet in the next few centuries to a few thousand years will lead to a sea level rise of about 23 meters.

“Look at Boston, New York, Miami, Mumbai or pick your coastal city around the world, and add 20 feet of height,” Bierman said. “It goes underwater. Don’t buy a house on the beach.”

Basic ideas

In 2016, Joerg Schaefer at Columbia University and his colleagues tested rock from the same 1993 glacier (called GISP2) and published a controversial study showing that its ice Greenland is now more than 1.1 million years old; that there were extended ice-free periods during the Pleistocene (a geological period that began 2.7 million years ago); and that if the ice had melted in the GISP2 area then 90% of the rest of Greenland would also melt. This was a major step in overturning the long-standing myth that Greenland is an immovable ice fortress, frozen for millions of years.

Then, in 2019, UVM’s Paul Bierman and an international team examined another piece of ice, this one quarried at Camp Century off the coast of Greenland in the 1960s. They were amazed to find twigs, seeds and insect fragments at the bottom of the ridge – indicating that the ice there had melted 416,000 years ago. In other words, the walls of the ice castle had failed more recently than previously thought.

“Once we discovered Camp Century, we thought, ‘Hey, what’s below GISP2?'” said Bierman, a professor at UVM’s Rubenstein School of Environment and Natural Resources and a partner in the Gund Institute for the Environment.

Although the ice and rock in the middle had been analyzed extensively, “nobody had ever looked at 3 inches of till to see if it was soil and if it had plant or insect remains,” he said. said so. So he and his colleagues requested a sample from the GISP2 core at the National Science Foundation Ice Core Facility in Lakewood, Colorado.

Now this new lesson has entered PNAS confirms that the theory of “weak Greenland” of 2016 is correct. And it deepens the reasons for concern, showing that the island was warm enough, for a long enough time, that the whole tundra environment, probably with stable trees, made itself where today another ice two kilometers deep.

“Now we have direct evidence that the ice was gone, but plants and insects lived there,” Bierman said. “And that’s indisputable. You don’t need to rely on numbers or models.”

From flowers

The first discovery of life—not just gravel and rock—at the bottom of the ice was made by geologist Andrew Christ who completed his Ph.D. worked at UVM and was a postdoctoral fellow in Bierman’s lab. Halley Mastro then took the bag and began to study the information closely.

“It was amazing,” he said. “Under the microscope, what looked like just specks floating on the molten core sample was actually a window onto the tundra landscape.

Working with Dorothy Peteet, a macrofossil expert at the Lamont-Doherty Earth Observatory and a co-author of the new study, Mastro was able to identify spores from spikemoss, the scale of a small willow, the compound eye of an insect , ” and we found an Arctic poppy, just one seed of that,” he said. “That’s a little flower that can really adapt to the cold.”

But that’s not the case. “It tells us that the Greenland ice sheet melted and there was land,” said Mastro, “because poppies don’t grow on miles of ice.”