CNN
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Evidences from a 2,000-foot-long ice core unveil a sudden and massive shrinkage of the West Antarctic Ice Sheet about 8,000 years ago, according to a recent study. This provides insight into the potential rapid melting of Antarctic ice and its impact on sea level rise.
Part of the ice sheet decreased by 450 meters (1,476 feet) — a height greater than the Empire State Building — over a period of just 200 years at the end of the last Ice Age. This was detailed in the study published Wednesday in the journal Nature Geoscience.
The study’s authors state that this is the first direct evidence showing such a rapid loss of ice in Antarctica. According to Eric Wolff, a glaciologist at the University of Cambridge in the UK and a study author, scientists were previously aware that the ice sheet was larger at the end of the last Ice Age, but knew little about when exactly the shrinking occurred.
With this new study, Wolff told CNN that they are now able to determine when and how quickly the ice retreated.
Now it is evident that the ice sheet retreated and thinned very rapidly in the past, Wolff said, highlighting the potential for it to happen again. “If it does start to retreat, it really will do it very fast,” he added.
Such a scenario could have catastrophic consequences for global sea level rise, as the West Antarctic Ice Sheet contains enough water to raise sea levels by about 5 meters – more than 16 feet — which would cause devastating flooding in coastal towns and cities around the world.
The study was hailed as “an excellent piece of detective work” by Ted Scambos, a glaciologist at the University of Colorado Boulder, who added that the key message is that the amount of ice stored in Antarctica can change very quickly, which would be challenging for many coastal cities to cope with.
Ice cores are historical records of the Earth’s atmosphere, consisting of layers of ice that formed over thousands of years. They contain ancient air bubbles and contaminants that provide a record of environmental changes over millennia.
The ice core analyzed in the study was extracted from Skytrain Ice Rise near the point where the ice starts to float and become part of the Ronne Ice Shelf.
The process of extracting the ice core involved drilling constantly for 40 days, and then shipping the samples to the UK for analysis.
The ice core’s water isotopes provide information on temperature in the past, while the pressure of trapped air bubbles in the ice reveals the ice thickness and elevation.
It was surprising for the researchers to discover just how rapidly the ice had thinned at the end of the last Ice Age, according to Wolff, who added that the West Antarctic Ice Sheet is particularly vulnerable to climate change due to the underlying land being below sea level, making it prone to rapid melting if warm water gets underneath.
Isobel Rowell, an ice core scientist at the British Antarctic Survey and a study co-author, expressed concern that once a runaway melting process starts, it would be difficult to stop.
Wolff emphasized the importance of addressing climate change to avoid reaching critical tipping points such as this.
The new data from the study will enhance the accuracy of models used to predict how the ice sheet will respond to future global heating.
David Thornalley, an ocean and climate scientist at University College London, described the study’s data as “striking,” while cautioning that it depicts a period 8,000 years ago and may not directly apply to current climate conditions, but still offers insight into how ice sheets can collapse.
The study adds to ongoing concerns about what is happening in Antarctica, including the rapid melting of the Thwaites Glacier in West Antarctica, known as the “Doomsday Glacier” for its potential catastrophic impact on sea level rise.
According to Scambos, the study indicates that the same processes currently observed in areas like the Thwaites Glacier have occurred before in similar areas of Antarctica, with ice loss occurring at a pace equivalent to worst-case scenarios for runaway ice loss.
