Home https://server7.kproxy.com/servlet/redirect.srv/sruj/smyrwpoii/p2/ Science https://server7.kproxy.com/servlet/redirect.srv/sruj/smyrwpoii/p2/ Two Antarctic glaciers are collapsing and this could have major consequences for sea level rise

Two Antarctic glaciers are collapsing and this could have major consequences for sea level rise

The Pine Island and Thwaites glaciers, which sit side by side in West Antarctica on the Amundsen Sea, are among the fastest-changing glaciers in the region, already accounting for 5% of global sea level rise. Scientists say glaciers are highly sensitive to climate change.
A new study, published in the Proceedings of the National Academy of Sciences on Monday, found that glaciers are weakening at the base, and that damage over the past few decades has accelerated their retreat and possible future collapse of their ice shelves.

Researchers led by Steph Lermit, a satellite expert at Delft University of Technology in the Netherlands, used satellite data to document the growth of damaged areas from 1

997 to 2019. The images show heavily cracked areas and open fractures in glaciers.

While the rapid loss of ice and the melting of these Antarctic glaciers are well documented, the new study suggests that there may be future disintegration of the ice shelves that lie ahead.

“We knew that giants were sleeping and these were the ones who were losing many kilometers (ice), but how far and how much uncertainty still remains,” Lermit said. “These ice shelves are in the early stages of disintegration, starting to break.”

The Tweets Glacier is one of the largest and most unstable ice streams in Antarctica. It is a gigantic mass of more than 192,000 square kilometers (74,000 square miles) – an area close in size to the US state of Florida or the United Kingdom.

The two glaciers effectively act as arteries connecting the West Antarctic ice sheet with the ocean. They are based on permanent floating ice shelves, which act as a support for the fast-flowing ice behind it. According to NASA, the region has enough ice to raise the sea level by 1.2 meters (4 feet).

So what’s happening to the glaciers now?

Man-induced warming of our oceans and atmosphere due to the increasing release of heat-absorbing greenhouse gases weakens the planet’s ice sheets.

This warming of the ocean has increased the melting and thawing (breaking off of ice) of the Pine Island and Twate glaciers, studies show, while declining snowfall means that glaciers cannot be filled.

The researchers found a weakening of the glacier shear boundary – areas at the edges of the floating ice shelf where fast-moving ice meets slower-moving ice or rock below.

“Usually the ice shelf acts like slow traffic. It floats on the ocean, but it supports the ice traffic behind it,” Lermit said. “So if you weaken this slow car, the ice melts faster.”

This is exactly what the researchers observed – and they believe that these highly weakening parts of the glacier will accelerate the mass loss of ice. The study argues that this process should be included in models that project sea level rise, of which it is currently not a part.

Researchers found that while the rupture of the Pine Island Glacier cut-off line has been documented since 1999, their satellite imagery shows that damage increased dramatically in 2016.

Similarly, damage to the Thwaites Glacier began to move upward in 2016, and fractures quickly began to open near the ground line of the glacier, where the ice meets the rock bed.

Researchers warn that the process creates feedback – where the weakening ice shelf accelerates the damage to the vulnerable boundaries of the glacier, which in turn leads to more damage and disintegration of the ice shelf.

Isabella Velikonia, a professor of terrestrial system science at the University of California, Irvine, who was not involved in the study, said that “with the weakening of the ice shelf included in the models, it is likely that the glacier will accelerate earlier and will be larger in size, which means that sea levels will rise faster than currently projected. “

Velikonia said there were other processes that played a “much bigger role” in the evolution of the glacier, such as the “rate of retreat of the ground line forced by a warmer ocean.”

Glaciers in trouble

The study is the result of a study published last week that found deep channels under the Twates Glacier that could allow warm ocean water to melt the bottom of its ice.

The quarries hidden under the ice shelf are likely to be the path through which warm ocean water passes under the ice shelf to the ground line, they said.

In the last three decades, the rate of ice loss from Twain and its neighboring glaciers has increased more than fivefold. If the Thwaites collapse, it could raise the sea level by about 25 inches (64 centimeters).

According to a new study, the ice sheet of Greenland has melted to a point of no return
And there is more bad news about glaciers on the other side of the world. On Monday, scientists announced that a piece of ice 44 square miles, approximately twice the size of Manhattan, had broken the largest remaining ice shelf in the Arctic in northeastern Greenland in two years, raising fears of its rapid disintegration.

The ice sheet of the territory is the second largest in the world after that of Antarctica and its annual melting contributes more than a millimeter to sea level rise each year.

These recent discoveries in Antarctica show that glaciers are “weakening from all angles,” Lermit said.

“Most weight loss in this part of Antarctica comes from below,” he said. “The warm ocean water reaches the base (of the glaciers) and weakens them. What we’ve seen is that it becomes so weakened that they accelerate, and once they accelerate, the shear fields accelerate and begin to collapse.”

Velikonia said the study “points to another Achilles’ heel of the system that is conducive to a faster retreat and caused by climate change.”

“It seems that the more we look at these systems, the more we see reasons for them to disappear faster than we thought,” she said. “We need to act quickly to control climate change to save our future. The time for action is now.”

Source link