Shrinking ice sheet in the West Antarctic made a 'surprising comeback' 10,000 ...

Shrinking ice sheet in the West Antarctic made a 'surprising comeback' 10,000 ...
Shrinking ice sheet in the West Antarctic made a 'surprising comeback' 10,000 ...

A special issue of Nature has published a series of studies looking at how monitoring Antarctica from space is providing crucial insights into its response to a warming climate. 

Here are their key findings: 

Three trillion tonnes of ice has been lost from Antarctica since 1992

The Antarctic Ice Sheet lost around three trillion tonnes of ice between 1992 and 2017, according to research led by Leeds University.

This figure corresponds to a mean sea-level rise of about eight millimetres (1/3 inch), with two-fifths of this rise coming in the last five years alone.

The finds mean people in coastal communities are at greater risk of losing their homes and becoming so-called climate refugees than previously feared.

In one of the most complete pictures of Antarctic ice sheet change to date, an international team of 84 experts combined 24 satellite surveys to yield the results.

It found that until 2012 Antarctica lost ice at a steady rate of 76 billion tonnes per year - a 0.2mm (0.008 inches) per year contribution to sea level rise.

However, since then there has been a sharp, threefold increase.

At some point since the last Ice Age, the West Antarctic Ice Sheet was smaller than it is today

Researchers previously believed that since the last ice age, around 15,000 years ago, the West Antarctic Ice Sheet (WAIS) was getting smaller

However, new research published by Northern Illinois University shows that between roughly 14,500 and 9,000 years ago, the ice sheet below sea level was even smaller than today.

Over the following millennia, the loss of the massive amount of ice that was previously weighing down the seabed spurred an uplift in the sea floor.

Then the ice sheet began to regrow toward today's configuration.

'The WAIS today is again retreating, but there was a time since the last Ice Age when the ice sheet was even smaller than it is now, yet it didn't collapse,' said Northern Illinois University geology professor Reed Scherer, a lead author on the study.

'That's important information to have as we try to figure out how the ice sheet will behave in the future', he said. 

The East Antarctic Ice Sheet was stable throughout the last warm period

The stability of the largest ice sheet on Earth is an indication to scientists that it could hold up as temperatures continue to rise.

If all the East Antarctic Ice Sheet melted, the sea level would rise by 175 feet (53 metres).

However, unlike the Greenland and West Antarctic ice sheets it seems it would be resistant to melting as conditions warm, according to research from Purdue University and Boston College.

Their research showed that land-based sectors of the East Antarctic Ice Sheet were mostly stable throughout the Pliocene (5.3 to 2.6 million years ago).

This is when carbon dioxide concentrations in the atmosphere were close to what they are today - around 400 parts per million.

'Based on this evidence from the Pliocene, today's current carbon dioxide levels are not enough to destabilise the land-based ice on the Antarctic continent,' said Jeremy Shakun, lead author of the paper and assistant professor of earth and environmental science at Boston College.

'This does not mean that at current atmospheric carbon dioxide levels, Antarctica won't contribute to sea level rise.

'Marine-based ice very well could and in fact is already starting to

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