Collapse of marine ice cliffs is not always inevitable

Scientists have made several disastrous predictions of global warming and sea level rise.

Friday, 18th June 2021

In connection with global warming and rising sea levels, scientists have made some terrifying predictions. One of the biggest disasters is the widespread collapse of ice cliffs along the edge of Greenland and Antarctica, which can raise the sea level to 4 meters by 2200. Now, new simulations suggest that giant glaciers in the ocean may not be affected by such collapses, as they once believed.

 One hypothesis that predicts a fatal sea level rise is called ocean ice cliff instability. Ice cliffs fail towards the sea, which is over 100 meters high, and are to be taken off to expose fresh ice. Those new cliffs then plunge into the collapsing ocean and rise, causing a relatively rapid retreat of the glacier that underpins sea level rise.

 Although it has been discussed for years, the phenomenon has yet to be seen in today's glaciers, says Jeremy Barsis, a glaciologist at the University of Michigan's Ann Arbor campus. "But that might not come as a surprise, because the record of outdoor or satellite observations is relatively short," he says.

 Due to the lack of field data, the Bassis decided to investigate the behavior of the ice cliffs using computer simulations. Unlike previous models, the researchers' simulations took into account how ice flows under pressure and how the ice breaks under excessive stress. This blended model is "a pioneering composite," says Nicholas Gorledge, who was not involved in the study as a glaciologist at the University of Victoria Wellington campus in New Zealand.

Also Read: Glaciers Worldwide are Melting Faster Than Ever Before.

 First, the researchers simulated the collapse of an ice cliff 135 meters high on dry land. In fact, for several weeks, the surface of the cliff shattered and fell to the base, so ice debris supported the cliff from further collapse. Researchers say these results are common in the field, Barsis.

 The following team simulated a 400-meter-high glacier, flowing in water 290 meters deep. These dimensions flow into deep fjords and are typical of Greenland's huge glaciers, says Vasis. When the cybercliff collapsed, ice that had fallen into the water floated up from the base of the cliff, and the failure was repeated, causing the glacier to run high and collapse. However, Vasis and his team reported in June 18 science that the runaway collapse was prevented by adding even a little back pressure to the bottom of the cliff to occur if the iceberg is stuck and cannot drift or if the iceberg is frozen in place, however. "I didn't think this was right," Bassis says. "But if a small cliff stuck to the shoal in front of the icy cliff, it was enough to support the face of [the cliff]," he says. Similar results were obtained in a simulation of an 800-meter-high glacier with a height of 690 meters, which is comparable to the size of the

 Antarctic Thwaites and Pine Island glaciers. Researchers have also found that at relatively warm ambient temperatures, the flow of ice upstream of the cliffs creates thinner glaciers, reducing the height of the cliffs and reducing the likelihood of runaway collapse.

In the simulation of the study, Science in the same issue, "I capture the realistic behavior I'm thinking of," says Golledge, who co-authored the comments for this study. In the future, field surveys can help validate the results of the group. Golledge says that less horrifying results if the simulation is maintained can mean that sea-level rise is slower in a shorter period of time than expected.

An analysis of  Bassis and his colleagues says "important work" and Ted Scambos, a glaciologist at the University of Colorado Boulder who has not participated in the study. The results "provide a balance between the potential for serious runaway collapse and the more realistic potential," he says.

The News Talkie Bureau

Source:

Sciencenews.org