An example from the past shows how the great Antarctic ice sheet can suddenly and dramatically disappear when the climate changes: In less than 200 years, the West Antarctic ice sheet became 450 meters thinner at one point, a research team reported in the journal Specialized in “Natural Earth Sciences”. This shows that once the tipping point is reached, the ice in Antarctica could disappear very quickly.
The group led by Eric Wolff from the University of Cambridge (Great Britain) used a 651-meter-long ice core from the so-called Skytrain Ice Rise. This peninsula-shaped ice dome is located on Ellsworth Land in West Antarctica. “We wanted to know what happened to the West Antarctic ice sheet at the end of the last ice age, when global temperatures were rising, albeit more slowly than the current warming caused by activity,” said Isobel Royle, co-author from the British Antarctic Survey. “The human being.” Cambridge.
The ice sheet consists of layers formed by falling snow and compressed over thousands of years. Each layer of ice contains bubbles of ancient air and materials introduced at that time. The proportion of certain molecules in the ice, the presence of certain substances, and the air pressure within the bubbles in the ice have now been analysed. In this way, events that occurred thousands of years ago can be reconstructed.
After the end of the last ice age about 8,200 years ago, the dome lost about 450 meters of ice in just 176 years. On average, the ice mass was shrinking by 2.5 meters per year.
Skytrain Ice Rise is located on the edge of the Ronne Ice Shelf, where the rock base lies below sea level. During the last ice age, the ice shelf was frozen to the bottom. Researchers believe that when the air and sea became warmer after the Ice Age, the sea undermined parts of the ice shelf. The ice now floated on the water and the resistance of the glacial ice pushing down from the ice dome was reduced. “Once the ice got thinner, it shrank very quickly,” Wolf explained. “This was clearly a turning point – a process that spiraled out of control.”
The scientists also found that between 7,700 and 7,300 years ago, the amount of sodium – which comes from salt in sea spray – in the ice gradually increased. Taking into account previous studies, they concluded that during this period the sea moved about 270 kilometers closer to the ice dome due to the retreat of the ice shelf.
Overall, according to Wolf's team, the new measurement data confirm that ice loss in Antarctica can occur relatively quickly. Scientists fear that current global warming could destabilize parts of the West Antarctica ice sheet, beyond the tipping point and lead to collapse. “This scenario is not only present in our model projections, but it could happen again if parts of this ice sheet become unstable,” Wolf said.
The West Antarctica Ice Sheet is particularly vulnerable because much of it lies on rocks below sea level. It is much smaller than East Antarctica, whose ice is considered more stable. According to the researchers, overall, the Antarctic ice sheets contain enough fresh water to raise global sea levels by about 57 metres.
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