CNN
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Recently discovered ice was taken from below Greenland ice sheet Decades ago According to a new report, much of the country was ice-free 400,000 years ago, with temperatures similar to those the world is now approaching – an alarming finding that could have catastrophic implications for sea-level rise.
The The study overturns previous assumptions that most of Greenland’s ice sheet has been frozen for millions of years, the authors said. Instead, moderate, natural warming has led to massive melting and sea-level rise of up to 1.4 meters (4.6 feet), the report says. Published Thursday in the journal Science.
“As geoscientists, looking at what nature has done in the past is the best clue to the future,” said Paul Bierman, a University of Vermont scientist and lead author of the study.
It’s “terrifying,” he tells CNN.
Levels of carbon dioxide in the atmosphere are now 1.5 times higher than they were 400,000 years ago. Global temperature continues to rise.
If Greenland’s ice sheet sees faster melting during moderate warming, it “may be more sensitive to human-induced climate change than previously understood — and at risk of irreversible, rapid melting in the coming centuries,” study authors said in a statement.
This will have a significant impact on sea level rise. If Greenland’s ice sheet completely melts, sea levels will rise About 7 meters (23 feet) wreaking havoc on the billions of people living along the world’s coastlines.
To complete the research, Pearman and an international team of scientists analyzed frozen sediment from an ice sheet collected in 1966 at Camp Century, a US military base in northwest Greenland. Scientists drilled through more than 4,500 feet of ice and took a 12-foot-long sample of soil and rock beneath the ice.
At the time, the technology didn’t exist to better understand the sediment, so it was lost in the freezer for decades, Bierman said. Then, in 2017, it was rediscovered in Denmark.
Bierman traveled to Copenhagen and brought two samples to the University of Vermont for testing. When the scientists began sifting through the sediment to separate it, they were surprised to find twigs, algae, leaves and seeds.
“We have a fossilized frozen environment,” Beerman said, “and, of course, the ice sheet means that the ice sheet is gone because you can’t grow plants under a mile of ice.”
Paul Bierman/University of Vermont
The Camp Centennial supplemental snow sample was processed at the University of Vermont.
Scientists still need to figure out how long ago the plants grew. To establish a timeline, the samples were sent to a team at Utah State University, which uses luminescence technology—a technique that allows us to determine when the sediment was last exposed to daylight.
Scientists estimate that the sediments were deposited in an ice-free environment about 416,000 years ago.
“This is the first bulletproof evidence that much of Greenland’s ice sheet has disappeared as it warmed,” Bierman said. “Greenland’s past, preserved in 12 feet of frozen soil, suggests a warm, wet and mostly ice-free future for Earth,” he added.
The potential implications for sea-level rise are enormous, study co-author Tammy Rittenour, a professor at Utah State University, said in a statement. “We’re looking at meters of sea level rise, probably tens of meters. Then look at the heights of New York City, Boston, Miami, Amsterdam. Look at India and Africa – most global population centers are near sea level.
In addition to contributing to sea level rise, the loss of ice accelerates global warming, as white snow that reflects the sun’s energy from the Earth’s surface is replaced by dark rock and vegetation, which absorb the sun’s energy.
“Once you start removing the ice there’s a feedback loop where we warm even faster,” Biermann said.
Andrew Shepherd, head of geological and environmental sciences at Northumbria University in England, who was not involved in the study, said the research is important because it “increases our confidence in predictions of how much melting we can expect to see in a warmer climate”.
Jason Box, professor of glaciology at the Geological Survey of Denmark and Greenland, who was not involved in the study, said the results could force a reevaluation of established thinking.
“Current greenhouse gas emissions-driven warming could shrink the Greenland ice sheet faster than predicted,” he told CNN.
For Bierman, this adds to the evidence that Greenland’s ice sheet is fragile.
Unless the world takes serious action to bring the level of planet-warming pollution to zero, while at the same time removing the carbon pollution already in the atmosphere, “we’re destroying the Greenland ice sheet, and sea level rise is going to come faster,” he said.
“Geologists generally don’t get too upset about what we find,” he said. “But it’s really sad.”
