Scientists drilled down an ice core from Antarctica and were alarmed by what they found

CNN
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Evidence from a 2,000-foot-tall ice core reveals that the West Antarctica ice sheet suddenly and dramatically shrank about 8,000 years ago, according to new research — providing a chance… An alarming vision How quickly Antarctica's ice will melt and sea levels will rise.

Part of the ice sheet thinned by 450 meters (1,476 feet) — a height greater than the Empire State Building — over just 200 years at the end of the last ice age. According to the study Published Wednesday in the journal Nature Geoscience.

This is the first direct evidence showing such rapid ice loss anywhere in Antarctica, according to the study authors.

While scientists knew that the ice sheet was larger at the end of the last ice age than it is today, it was much smaller. Eric Wolff, a glaciologist at the University of Cambridge in the United Kingdom and author of the study, said scientists did not know exactly when this shrinkage occurred.

This study changes that, he told CNN. “We were able to determine exactly when it retreated, but we were also able to determine how quickly it declined.”

Wolf said it is now clear that the ice sheet retreated very quickly in the past, and the danger is that it could start again. “If it starts to decline, it will do so very quickly,” he added.

This could have serious consequences for global sea level rise. The West Antarctica ice sheet contains enough water to raise sea levels by about 5 meters – more than 16 feet – which could cause devastating flooding in coastal towns and cities around the world.

Ted Scambos, a glaciologist at the University of Colorado Boulder, said the study is “excellent detective work” on much of the Antarctic ice sheet.

The main message, he told CNN, is that “the amount of ice stored in Antarctica could change very quickly — at a pace that is difficult to handle for many coastal cities.”

Ice cores are historical archives of the Earth's atmosphere. Made up of layers of ice Formed by falling and compressed snow Over thousands of years, they have contained bubbles of ancient air as well as pollutants that provide an environmental record Changes over thousands of years.

The ice cores analyzed in the study were drilled from the Skytrain Ice Rise located at the edge of the ice sheet, near the point where the ice begins to float and becomes part of the Ronne Ice Shelf.

Scientists extracted it in 2019, in a painstaking process that involved drilling continuously for 40 days, pulling out a thin cylinder of ice a few feet at a time. They then cut the heart into pieces, packed them in insulated boxes kept at minus 20 degrees Celsius, and sent them to the UK via plane and then ship.

Once in the UK, scientists measured water isotopes found in the ice cores, which provide information about past temperature. Warmer temperatures indicate lower ice — think of it like a mountain, Wolf said, the higher you climb the colder it gets.

They also measured the pressure of air bubbles trapped in the ice. Lower, thinner ice contains higher pressure air bubbles.

Wolf said: It was a surprise when the data revealed how quickly the ice melted at the end of the last ice age. “We spent a lot of time checking that we had not made anything wrong with the analysis.”

The West Antarctica ice sheet is particularly vulnerable to climate change, because the land beneath it lies below sea level and slopes downward. When warm water reaches the bottom, it can melt very quickly. “It could have a runaway process, and that's clearly what happened 8,000 years ago,” Wolf said.

What makes the findings so worrying is that once this escape occurs, “there is very little, if anything, we can do to stop it,” said Isobel Royle, a glaciologist at the British Antarctic Survey and co-author of the study. She told CNN.

The crucial thing “is not to test it too much,” Wolf said, and that means tackling climate change. “We can still avoid these tipping points,” he said.

The report says the new data will help improve the accuracy of models that scientists use to predict how the ice sheet will respond to global warming in the future.

David Thornalley, an oceanographer and climate scientist at University College London, said the study data was “astonishing”. He cautioned that when the study looked at a period 8,000 years ago, when climate conditions were different, the results were not a direct example of what would happen today. But he added that they could still provide “insight into the way ice sheets might collapse.”

The study comes as scientists continue to sound the alarm about what is happening to the most isolated continent on Earth.

For example, Thwaites Glacier, also in West Antarctica, It dissolves quickly. A 2022 study said the Thwaites River – dubbed the “Doomsday Glacier” because of the catastrophic effect its collapse could have on sea level rise – was devastating. Hanging by her nails As the planet warms.

This new study heightens those concerns, Scambos said. “(It) shows that the same processes we are seeing, which are just beginning in areas like the Thwaites Glacier, have occurred before in similar areas in Antarctica, and in fact, the pace of ice loss has been on par with our worst fears about runaway ice. Loss.”