A newly discovered core pulled from the Greenland ice sheet decades ago has revealed that much of the country was ice-free around 400,000 years ago, when temperatures were similar to those the world is now approaching, according to a new report — an alarming finding that could have disastrous implications for sea level rise.
The study overturns previous assumptions that most of the Greenland ice sheet has been frozen for millions of years, the authors said.
Instead, moderate natural warming has led to large-scale melting and sea level rise by more than 1.4 meters, according to the report published Thursday in the journal Science.
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“When you look at what nature has done in the past, as geoscientists, that’s our best clue for the future,” said Paul Bierman, a scientist at the University of Vermont and lead author of the study.
What this indicates is “scary,” he told the CNN .
Carbon dioxide levels in the atmosphere are 1.5 times higher now than they were 400,000 years ago, and global temperatures continue to rise.
If the Greenland ice sheet underwent rapid melting during a period of moderate warming, it “may be more sensitive to human-caused climate change than previously thought — and will be vulnerable to rapid, irreversible melting over the next few centuries,” the study authors said in a report. declaration.
This would have significant impacts on sea level rise. If the Greenland ice sheet completely melted, sea levels would rise by about 7 meters, causing devastation for billions of people living along the world’s coasts.
To complete the research, Bierman and a team of international scientists spent years analyzing frozen sediments from an ice core collected in 1966 at Camp Century, a US military base in northwest Greenland.
Scientists drilled through more than 1370 meters of ice to extract a 3.6 meter long sample of soil and rock under the ice sheet.
At the time, there was no technology to understand the sediment very well, so it was lost in a freezer for decades, Bierman said. Then, in 2017, it was rediscovered in Denmark.
Bierman went to Copenhagen and brought back two samples to test at the University of Vermont. When the scientists began to sift through the sediment, they were surprised to see twigs, mosses, leaves and seeds.
“We have a fossilized frozen ecosystem here,” Bierman said, “and what that means, of course, is that the ice sheet is gone because you can’t grow plants under a mile of ice.”
Scientists still needed to figure out how long the plants had been growing. To establish the deadline, the samples were passed to a team at Utah State University, which uses luminescence technology – a technique that allows dating the last time the sediment was exposed to daylight.
Scientists calculated that the sediment was deposited in an ice-free environment about 416,000 years ago.
“It’s really the first bulletproof evidence that much of the Greenland ice sheet disappeared when it got warm,” Bierman said. “Greenland’s past, preserved in 3.6 meters of frozen ground, hints at a warm, wet and ice-free future for planet Earth,” he added.
The potential implications for sea-level rise are enormous, said Tammy Rittenour, a professor at Utah State University and a co-author of the study in a statement.
“We are looking at meters of sea level rise, probably tens of metres. And then look at the elevation of New York City, Boston, Miami, Amsterdam. Look at India and Africa – most global population centers are close to sea level.”
In addition to contributing to sea level rise, ice loss also accelerates global warming, as white ice, which reflects the sun’s energy away from the Earth’s surface, is replaced by darker rocks and vegetation, which absorb the sun’s energy.
“There’s a feedback that occurs when you start to get rid of the ice sheet where we warm up even faster,” Bierman said.
Andrew Shepherd, head of geography and environmental sciences at Northumbria University in the UK, who was not involved in the study, said the research is important because it “boosts our confidence in predictions of how much melting we can expect in a warmer climate.”
Jason Box, professor of glaciology at the Geological Survey of Denmark and Greenland, who was also not involved in the study, said the results could force a reassessment of established thinking.
“The current warming caused by greenhouse gas emissions could reduce the Greenland ice sheet faster than predicted,” he told the CNN .
For Bierman, it all adds up to evidence that the Greenland ice sheet is fragile.
Unless the world takes radical measures to reduce the levels of pollution that warms the planet to zero and simultaneously works to remove the carbon pollution already in the atmosphere, he said: “we are dooming the Greenland ice sheet and much of this rise in sea levels will come quickly”.
“Geologists are generally not too upset about what we find,” he said. “But this is really disturbing.”
Source: CNN Brasil
Bruce Belcher is a seasoned author with over 5 years of experience in world news. He writes for online news websites and provides in-depth analysis on the world stock market. Bruce is known for his insightful perspectives and commitment to keeping the public informed.
