We've known for some time that a huge crack opened up on Antarctica's Pine Island Glacier in 2012. But it wasn't clear how much time the 10.5-kilometre-long crack took to form. New research explains this: The crack appeared in about 5.5 minutes.
This means the crack shot through the ice at a speed of about 128 kilometers per hour, the researchers concluded in the journal Provided by the Arabian Gulf University. This is something they have never seen before. “To our knowledge, this is the fastest opening of a crevasse (in a glacier, ed.) ever observed,” confirms researcher Stephanie Olinger. “It shows that an ice shelf can – under certain conditions – break off.”
Ice shelf
The study by Olinger and colleagues looks at Pine Island Glacier. This glacier is located in West Antarctica and flows into the Amundsen Sea. In addition, once the glacier reaches the sea, it does not stop suddenly; Part of the glacier still lies on the water. This floating portion is also referred to as the Pine Island Ice Shelf. It is an important part of the glacier because it provides back pressure to the land portion of Pine Island Glacier and thus stabilizes it, or prevents the glacier from accelerating the flow of ice into the sea. However, in recent years, this ice shelf has become increasingly thinner. And not only that; Large pieces of ice also regularly break off from the ice shelf. A process also referred to as childbirth.
birth
Before such a breakup occurs, we often first see a large crack developing in the ice shelf. Such a crack often passes directly through an ice sheet hundreds of meters thick and gradually cracks more and more until it reaches the edges of the ice shelf. This is the moment when part of the ice shelf on the seaward side of the fissure can break off from the rest of the glacier.
Broken glass
In 2012, researchers saw in satellite images that a large crack had opened in Pine Island Glacier. But because the observing satellite only flew over Pine Island Glacier once every three days, it wasn't clear exactly how much time it took for the fissure to cover a distance of 10.5 kilometers. It could have been three days. But also much shorter. Scientists did not know. “Is the cracking a bit like breaking glass or something like that Fucking putty Differentiates? “That was the question,” Olinger said.
Seismographs
Satellites were unable to provide an answer, so researchers began looking for other witnesses. They ended up taking seismometers that other researchers had previously placed on the Pine Island ice shelf, and also listening to them in 2012. By combining this data with satellite images, they were able to make a good estimate of the speed at which the crack developed. Their calculations reveal that it moved through the ice at a speed of about 35 meters per second, or 128 kilometers per hour.
Surprisingly
“On the one hand, it was surprising, because we had never observed such rapid crack formation before,” says Olinger. Scientias.nl. “But on the other hand, it was not surprising, because we know that cracks in many other materials also develop quickly. In addition, we were also aware that we can only observe ice shelves on a limited scale. And so we have always known that many things happen.” There we can't see it.One of them is the rapid formation of cracks.
Pine Island is unique
It should be noted that the research definitely does not indicate that all cracks in glaciers develop this quickly. Pine Island Glacier may be a different story, Olinger explains. “Pine Island Glacier is flowing at a rate of 10 meters per day.” This makes it a fast-flowing glacier. “Because Pine Island Glacier is flowing so fast, its edges are also under great pressure, causing cracks to form and grow regularly. In addition, the ice front (the front part of the glacier) has retreated significantly over the past 20 years. As the front retreats During glaciation, the geometry of the ice shelf changes, redistributing the pressure on the edges of the ice shelf of such a fast-flowing glacier, causing the glacier to flow faster and destabilize. By comparison, the Ross Ice Shelf – the largest ice shelf in Antarctica – flows quickly A maximum of 3 meters per day. This ice shelf is quite stable in size and many of the cracks that have developed in this ice shelf have not changed in length since we started monitoring the ice shelves. In short, not all glaciers break like glass, but the conditions surrounding an island river “We know – from studying glaciers for years – that ice can flow very slowly,” Olinger explains, “but we also know that ice can break like glass: just drop Ice cubes in the kitchen or walking on a freshly frozen lake. When ice is quickly placed under great pressure, it breaks like glass. “And that's pretty much what's happening here (on the Pine Island ice shelf, ed.).”
Important research
Research is important. Because Antarctica's glaciers contain enough ice, when it melts, sea levels will rise dramatically. However, it is not entirely clear how these glaciers will fare in the future due to global warming. This is partly because we don't yet fully understand how cracks in ice shelves form and grow and what effect warmer oceans could have on them. The new research doesn't provide ready-made answers, but it does reveal that things can happen quickly under certain conditions. “It's certainly remarkable that cracks can open at such a high speed,” Olinger says. “But it is difficult to say whether this is a cause for concern, because we do not yet know whether this rapid formation of cracks is common or not. We also do not know yet whether this will happen more frequently if the Antarctic ice sheet persists.” “In response to climate change. As oceans warm and ocean currents change, Antarctic ice shelves will become increasingly thinner due to melting. What happens next to existing cracks (such as those in the Ross Ice Shelf)? We don't know yet.”
“I think the most important implication of this research is that cracks can open at such a high speed. It suggests that cracking could lead to rapid changes in ice shelf geometry, perhaps even leading to the complete collapse of such an ice shelf in a short time. But we don't We don't yet know exactly what conditions are needed to enable such rapid crack formation, so a lot of work needs to be done before we can draw conclusions about how frequently such rapid crack formation might occur in the future.
