Antarctica's 'Doomsday Glacier' Worst-Case Scenario Won't Collapse

Thwaites Glacier in Antarctica earned its nickname “Doomsday Glacier” because of its potential to flood coastlines around the world if it were to collapse. It already contributes about 4% annual sea level riseas it loses ice, and one theory suggests the glacier may soon start falling into the oceanlike a row of dominoes.

But is such a rapid collapse really as likely as feared? New research into Thwaites Glacier's susceptibility to what is known as sea ​​ice cliff instabilitygives some hope. But conclusionsdoes not mean that Thwaites is stable.

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Polar scientist Mathieu Morlighemwho led the study explains the results.

Why is Thwaites Glacier important?

Thwaites Glacier drains a huge area of ​​Antarctica's ice sheet – about 74,000 square miles(192,000 square kilometers), an area larger than Florida. If a snowflake fell into this drainage system, it would eventually become part of an iceberg in the ocean off Thwaites.

What we are seeing now with Thwaites Glacier is a catastrophe in slow motion.

The bedrock beneath the Thwaites Glacier is below sea level and slopes down towards the interior of the countryso the glacier gets deeper toward the inside of the ice sheet. Once the glacier starts losing more ice than it gains from new snowfall and starts to retreat, it's very difficult to slow down because of that slope. And Thwaites is already retreating at an accelerated rate as the climate warms.

Thwaites Glacier contains enough ice to raise global sea levels by more than 2 feet(0.65 meters). Once Thwaites begins to destabilize, he will also destabilize neighboring glaciersSo what happens to Thwaites affects the entire West Antarctic Ice Sheet, and that affects sea level rise along coastlines around the world.

What is sea ice cliff instability?

Instability of sea ice cliffs is a relatively new conceptproposed by scientists over the past decade.

Many glaciers around Antarctica have huge floating extensions called ice shelvesthat support the glacier and slow its movement into the ocean. As the climate warms, we've seen some of these floating extensions collapse, sometimes very quicklyover several weeks or months.

If the Thwaites Ice Shelf were to collapse, it would expose a very high ice cliff facing the ocean along its 75-mile (120-kilometer) frontIce can only support so much force, so if a cliff is too high, it will collapse into the ocean.

Once this happens, a new ice cliff further back will be exposed, and the new cliff will be even higher because it is further from the shore. The theory of sea ice cliff instability suggests that if the cliffs collapse quickly enough, may have a domino effectEver higher ice cliffs collapse one after another.

However, no one has observed sea ice cliff instability in action. We don't know if it will happen because a lot depends on how quickly the ice breaks up.

What have you learned about the risk to Thwaites?

When sea ​​ice cliff instability theoryThe model presented for the first time used a rough approximation of how ice cliffs might collapse after an ice shelf disappeared.

Research conducted since then has shown that ice cliffs will not collapse systematicallyuntil the ice reaches a height of about 442 feet (135 meters). Even then, they will erode more slowly than expected until they are much higher.

We used three high-resolution models to explore what implications this new physical understanding of ice cliff instability will have for Thwaites Glacier this century.

Our results show that if the entire Thwaites Ice Shelf were to collapse today, its ice front would not retreat rapidly inland only because of the instability of the sea ice cliff. Without the ice shelf, the glacier ice would flow much faster toward the ocean, thinning the glacier front. As a result, the ice cliffs would not be as high.

We found that Thwaites will remain fairly stable until at least 2100. We also modeled the collapse of the ice shelf in 50 years, when glacier grounding line– where its squat ice meets the ocean – would have retreated further inland. Even then, we found that the instability of the sea ice cliff itself would not have caused a rapid retreat.

The findings cast doubt on some recent estimates of how quickly Thwaites could collapse. This includes a worst-case scenario that the Intergovernmental Panel on Climate Change outlined in its latest appraisal reportbut is marked as “low probability”.

Thwaites is the glacier that worries everyone. If you model the entire ice sheet, this is where the sea ice cliff instability starts and where it spreads far into the country. So if Thwaites is not as vulnerable to ice cliff collapse as we thought, that's a good sign for the entire ice sheet.

But sea ice cliff instability is only one mechanism for ice loss. This finding does not mean Thwaites is stable.

What else is causing glaciers to retreat at an accelerated rate?

There are many processes that make the Antarctic ice sheet unstable, some of which are well understood.

The interaction of ice and the ocean explains most of the recent ice mass lossbye. Antarctica is very cold placeso atmospheric warming is not having much of an effect yet. But warm ocean currents are penetrating under the ice shelves, and they thinning of ice from belowwhich weakens the ice shelves. When this happens, the ice flows faster because there is less resistance.

Over the last few decadesIn the sector of the Amundsen Sea where the Thwaites and Pine Island glaciers are located, there was an intrusion of warm water from the Antarctic Circumpolar Current, which was melting ice from below.

What does climate change have to do with this?

Antarctica may seem like a faraway place, but human activities that are warming the planet– such as burning fossil fuels – have dramatic effects at the poles. Ice loss contributes to sea level rise, affecting coastal regionsall over the world.

The choices people make today will determine how quickly the waters rise.

This article was originally published on Talk. Read original article.