Quirks & Quarks

Antarctica's rising bedrock could stabilize the ice melt

Ice is melting and land is rising - the ups and downs of Antarctica
Rising bedrock will help stabilise the melting West Antarctic Ice Sheet. (Getty Images)

Rising bedrock in the Antarctic is coming to the rescue of a rapidly melting glacier.

The West Antarctic Ice Sheet is part of the continental ice that covers the western portion of Antarctica. It comprises just under 10 per cent of the Antarctica's total ice mass, which is about 25.4 million kilometres cubed.

It is well documented that melting Antarctic glaciers are already contributing to sea level rise by an estimated 0.24 millimetres per year, and the problem is very quickly getting worse.

The West Antarctic Ice Sheet is melting at an alarming rate.

Dr. Valentina Barletta, a post-doctoral researcher at the Technical University of Denmark, has been studying the West Antarctic Ice Sheet.

Ice sheet in trouble

"This ice sheet is one of the most massive reserves of freshwater in the form of ice," says Barletta. "The thickness is up to three kilometres and it is all grounded or below sea level. And this is a very important characteristic of this place, and what's going on now is that a part of this is slowly melting. And if in the future all these ice sheets melt, it would raise the sea level by three metres. So that's a huge amount of water."

Scientists have predicted this glacier is doomed because of the effects of climate change. But Barletta's study published this week in the journal Science has found there could be a rare glimmer of hope for the ice sheet as a result of bedrock in that part of the continent rising.

Rapidly rising bedrock

As the glacier melts, it becomes lighter and reduces the load on the bedrock below. In a process known as "rebound" or "uplift," the bedrock actually rises, reducing the amount of sea water around the ice.

For the part of the West Antarctic Ice Sheet that is currently below sea level, Barletta says this feedback is good news.

Earth's squishy interior gives rapid rise to West Antarctica: 

"Reducing the depth of the water will help the ice to stay grounded and not to float. This is the opposite action [from melting], so mechanically, it will make the ice sheet bigger and more stable," says Barletta.

What this could mean for the ice sheet

"This is one action, and of course it's just counteracting all the erosion from the ocean," says Barletta. "So the action that is faster, I would say, wins. If the erosion from the ocean is too fast, of course there's nothing we can do. But if this uplift from the Earth is fast enough, it could balance the effect of the erosion."

According to this latest study, the uplift from the bedrock does seem to be fast enough to stabilize the glacier.

"In this region, where the ice is melting, a lot the uplift is very fast," says Barletta. "It is up to 41 millimetres [per year]. However, below the ice, where we don't have measurements, I can do simulations and calculate this. We have much more like 50 or 60 millimetres [per year], and that is going to increase in the future."

Rift in the Pine Island Glacier ice shelf.

It was once thought that uplift could take thousand of years before it made a difference to the glacier, but now scientist feel it will only take decades because the process is well underway. It is predicted that by the end of the century, the bedrock below part of the West Antarctic Ice Sheet, known as the Pine Island Glacier, will rise an astounding 8 metres.