Historic ice loss in Antarctica warns of potential climate catastrophe

By Isobel Williams via SWNS

The West Antarctic Ice Sheet shrunk by 450 meters - more than the height of the Empire State Building - in less than 200 years, reveals new research.

Scientists have discovered that around 8,000 years ago, at the end of the last Ice Age, part of the Antarctic ice sheet suddenly and dramatically thinned.

The University of Cambridge researchers fear that today’s rising temperatures might destabilize parts of this ice sheet in the future, and these new findings show just how dramatic the losses could be.

To get their results, published in the journal Nature Geoscience, the team studied ice cores, which they transported back to their Cambridge lab at -20°C.

Ice cores are made up of layers of ice that formed as snow fell and were then buried and compacted into ice crystals over thousands of years.

From analyzing these cores they could uncover the temperature at the time the snow fell, and the air pressure of the bubbles within.

These measurements told them that ice thinned rapidly 8,000 years ago.

Dr. Isobel Rowell, of the British Antarctic Survey, said: “We wanted to know what happened to the West Antarctic Ice Sheet at the end of the Last Ice Age, when temperatures on Earth were rising, albeit at a slower rate than current anthropogenic (man-made) warming.

“Using ice cores, we can go back to that time and estimate the ice sheet’s thickness and extent.

“We already knew from models that the ice thinned at around this time, but the date of this was uncertain.

“We now have a very precisely dated observation of that retreat which can be built into improved models.”

The researchers estimate that the thinning was triggered by warm water getting underneath the edge of the West Antarctic Ice Sheet.

This likely untethered a section of the ice from bedrock, allowing it to float suddenly and forming what is now the Ronne Ice Shelf, which then allowed neighboring Skytrain Ice Rise, no longer restrained by grounded ice, to thin rapidly.

They also discovered that the sodium content of the ice increased around 300 years after the ice thinned, which suggests that the ice shelf shrunk back so that the sea was hundreds of kilometers nearer to their site.

Model predictions suggest that a large part of the West Antarctic Ice Sheet could disappear in the next few centuries, causing sea levels to rise.

The team hopes that their findings will help them to accurately predict the speed in which this loss could happen.

Professor Eric Wolff, of Cambridge’s Department of Earth Sciences, added: “We now have direct evidence that this ice sheet suffered rapid ice loss in the past.

“Once the ice thinned, it shrunk really fast. This was clearly a tipping point — a runaway process.

“This scenario isn’t something that exists only in our model predictions and it could happen again if parts of this ice sheet become unstable.

“It’s now crucial to find out whether extra warmth could destabilize the ice and cause it to start retreating again.”