Two glaciers in Antarctica are weakening at their foundations: what does it mean?

2 Antarctic glaciers begin to disintegrate 0:43

(CNN) ––

Satellite images show that two large glaciers in Antarctica suffer rapid damage at their most vulnerable points.

This can lead to the breakdown of vital ice sheets, leading to serious consequences for global sea level rise.

The Pine Island and Thwaites glaciers, located side by side in West Antarctica in the Amundsen Sea, are among the fastest changing glaciers in the region.

Currently, they represent 5% of the global rise in sea level.

Scientists indicate that glaciers are very sensitive to climate change.

• READ: Antarctica's colossal Thwaites glacier is rapidly melting and scientists may have discovered why

According to a new study, published in the

Monday, glaciers are weakening to their foundations.

The report notes that this damage in recent decades has accelerated its retreat and the possible future collapse of its ice sheets.

Stef Lhermitte, a satellite expert at Delft University of Technology in the Netherlands, led the team of researchers.

The scientists used satellite data to document the growth of damaged areas from 1997 to 2019. The images revealed areas with many open cracks and fractures in the glaciers.

The rapid loss of ice and the melting of these Antarctic glaciers have been well documented.

However, the new study suggests that there could be a future disintegration of the ice sheets that support the glaciers.

"We knew that these were sleeping giants that lost many kilometers (of ice), but how far and how much is still a great uncertainty," said Lhermitte.

"These ice sheets are in the initial phase of disintegration, they are beginning to break up."

Glaciers melt from high temperatures 2:11

The Thwaites Glacier is one of the largest and most unstable ice currents in Antarctica.

It is a giant mass of more than 192,000 square kilometers, an area similar in size to the state of Florida, the US or Great Britain.

The two glaciers effectively act as arteries connecting the West Antarctic ice sheet to the ocean.

At its base are permanent floating ice sheets that function as buttresses for the rapidly flowing ice behind them.

The region has enough ice to raise global sea level by 1.2 meters, according to NASA.

What is happening to the glaciers in Antarctica?

Human-induced warming of the oceans and the atmosphere, due to the increasing release of greenhouse gases, weakens the planet's ice sheets.

• LOOK: Melting glaciers in the Russian Arctic reveals five new islands

This warming increased the melting and detachment (breaking of pieces of ice) of the Pine Island and Thwaites glaciers, according to studies.

Also, the decrease in snowfall means that glaciers cannot be replenished.

The damage the researchers found pointed to a weakening of glacier cut margins in Antarctica.

That is, areas at the edges of the floating ice sheet where fast-moving ice meets slower-moving ice or rock below.

“Usually the ice sheet acts like slow traffic.

It floats in the ocean but reinforces the ice traffic behind it, ”Lhermitte explained.

"So if you weaken this slow car, the ice discharges more quickly."

They record in slow motion the collapse of a glacier 0:58

That is exactly what the researchers observed.

In that sense, they believe that these severely weakened parts of the glacier will accelerate the massive loss of ice.

The study argues that this process should be included in models that project sea level rise, of which it is not currently part.

The researchers found that while the breaking of the cutting margins of the Pine Island Glacier has been documented since 1999, their satellite images show that the damage accelerated dramatically in 2016.

We use satellite imagery to show how the shear margins of both @AntarcticPIG and @ThwaitesGlacier have weakened.

Here you see a @NASA_Landsat 🛰️ time lapse of @AntarcticPIG showing how the shear margin is tearing apart [2 / n] pic.twitter.com/u7vRfFxcOH

- Stef Lhermitte (@StefLhermitte) September 14, 2020

Similarly, damage to the Thwaites Glacier began to move upstream in 2016. Additionally, the fractures began to open rapidly near the glacier's grounding line, which is where the ice meets the bedrock.

We hypothesize that this damage preconditions these ice shelves for further disintegration.

First, because it already compromises the integrity of both ice shelves.

[4 / n] pic.twitter.com/HqaPjg8OHv

- Stef Lhermitte (@StefLhermitte) September 14, 2020

The researchers warn that the process is creating a feedback loop, where the weakened ice shelf accelerates damage to the glacier's vulnerable shear margins.

Which in turn leads to further damage and disintegration of the ice shelf.

An example of this preconditioning can be seen in the unprecedented retreat of the @AntarcticPIG ice shelf front over the last years where the ice shelf lost 30% of its area.

[5 / n] pic.twitter.com/cCccu3QQTS

- Stef Lhermitte (@StefLhermitte) September 14, 2020

Isabella Velicogna, a professor of Earth System Sciences at the University of California, Irvine, who was not involved in the study, said that “with a process of weakening the ice sheet included in the models, the speed of the glacier is likely to increase. before and will be of greater magnitude.

"Which means that sea level will rise faster than is currently projected," he added.

Velicogna said there are other processes that play "a much larger role" in the evolution of glaciers.

For example, "the rate of retreat of the land line forced by a warmer ocean."

Glaciers in trouble

The study comes after research published last week, which found that channels deep under the Thwaites Glacier may be allowing warm ocean water to melt the bottom of its ice.

Hidden cavities under the ice shelf of glaciers in Antarctica are likely the route by which warm ocean water passes under the ice sheet to the grounding line, they said.

In the past three decades, the rate of ice loss from Thwaites and its neighboring glaciers has increased fivefold.

If Thwaites were to collapse, it could cause a rise in sea level of around 64 centimeters.

And there is more bad news for glaciers on the other side of the world.

On Monday, scientists announced that a 113-square-kilometer chunk of ice, roughly twice the size of Manhattan, has broken off the largest Arctic ice shelf in northeast Greenland in the past two years.

This fact raises fears of its rapid disintegration.

The ice sheet of the territory is the second largest in the world behind Antarctica.

Its annual melting contributes to a rise of more than a millimeter in sea level each year.

Recent findings over Antarctica show that glaciers are "weakening from all angles," Lhermitte said.

"Most of the weakening in this part of Antarctica comes from below," he said.

“The warm water from the ocean reaches the bottom (of the glaciers) and weakens them.

What we see is that it gets so weak that it accelerates and once it accelerates, the cutting margins accelerate and start to break.

Velicogna said the research "points to another Achilles heel of the system conducive to a more rapid reversal and triggered by climate change."

"It seems that the more we observe the evolution of these systems, the more reasons we see for them to disappear more quickly than we think," he said.

“We have to act quickly to control climate change to preserve our future.

The time to act is now".

Antarctica melting glaciers