Never in the history of the Swiss Alps has a glacier caused such destruction as the one that collapsed in stunning fashion on May 28. After a few days of ominous advances, coupled with rockslides pipeline on top, the front section of the Birch Glacier, or Birchgletscher, hurtled into the Lötschental Valley at speeds of up to 200 kilometers per hour (120 mph).
Most of the evacuated villages Blatten (Pop. 300) are buried in fragment cones up to 100 meters (328 feet). One person is missing and assumed to be dead.
“The collapse of the birch glacier is unprecedented in terms of the amount and extent of damage caused by the Swiss Alps,” Zurich, Switzerland reported in an updated press release on June 4.
Although the full collapse of the glacier was not confirmed until it happened, there are many warning signs that help prevent large-scale loss of life. On May 17, a major landslide from Kleines Nesthorn reached 500 meters (1,640 feet) of the Lonza River, prompting parts of Blatten to evacuation. Within a few days, hundreds of cows, sheep and rabbits were crossed through the dangerous area.
The disaster in Blyden is not a typical landslide or avalanche. Recently, glacologists have grown in interest in many small but high-impact situations where large rock landslides landslides on glaciers that land on top of glaciers resulted in a complex series of events that ultimately led to large, large teams known as “sudden large-scale low-altitude mountain glaciers.”
These dramatic destructions vary greatly in their location, evolution and impact, but scientists have discovered some key themes. As human-changing climates transform alpine landscapes (including permafrost in rocky slopes as well as the glaciers themselves), it seems to lay the foundation for more such events.
Anatomy of glacier collapse
Most glaciers around the world are retreating, their front edges collapse and their depth thins as the climate warms. However, unlike any other glacier in Switzerland, the birch glacier has been advancing and thickening towards the front edge. This is a particular paradox, as warming in alpine regions is faster than the global average. Switzerland has heated around 2.9°C since the late 1800s, about twice the speed of the world, while glaciers in the Alps lost 10% of their mass in 2022 and 2023 alone.
Strangely, it seems that over the past few years it has helped to make the front of the birch glacier interact. The generated layers of rocks and deposits appear to distort the front of the glacier and separate it from the snow below. Usually, thin dust or pollution will help enhance glacier melting by absorbing more heat, rather than the shallow snow and ice that is covered. However, once a layer of rock or sediment is more than a few centimeters thick, like a birch glacier, the insulation effect exceeds absorption and helps reduce net melting. Therefore, even though the upper layer continues to be sparse, the frontmost part of the glacier has been increasing for many years.
According to Eth Zurich, the front edge of the glacier is up to 15 meters (50 feet) thick from 2017 to 2023. In the last six years, about one-third of the collapsed portion of the birch glacier has advanced about 50 meters (165 feet).
Starting from May 17, with millions of cubic meters of rock in the upstream mountain shed, huge sediments fell on the top of the lower birch glacier. The added weight and the compression and warming generated appear to annoy the glaciers with melting (up to 1 cm or 0.4 inches). It only adds to the load after raining later this month. Once the glacier starts to accelerate, friction at its bottom causes additional warming and produces 0.5 cm (0.2 inches) of fusion water per day.
A new avalanche
Events like the collapse of birch glaciers are not as weird as we once thought. A paper in the 2021 frozen circle led by Andreas Kääb of the University of Oslo analyzed 20 events, most of which were most of the activities since 1990, grouped into large batches of sudden Low-horned glaciers. A considerable range of these cases exceeds approximately 9.3 million cubic meters and 20 million tons of debris produced in the birch glacier disaster.
“The vast catastrophic detachment of glaciers so far has not yet recognized the rare but enormous potential of life and huge losses in mountainous areas,” Kääb and his co-authors wrote.
These events are a subset of rock ice avalanches (a mixture of rock and ice) that can occur from a wider range of conditions that are not related to climate change. The most notorious rock avalanche in modern history was caused by a magnitude 7.9 earthquake off the Peruvian coast. On May 31, 1970, a magnitude 7.9 earthquake occurred on the coast of Peru. The huge rocks of ski rocks from Huascarán Mountain slipped into large glaciers and eventually fell into saturated soil, potentially creating muddy mud, about 10 times the size of Birch Glacier Collapse. At a speed of up to 435 km/h (270 mph), the mudslide consumed the city of Yungay and several nearby villages, with estimated deaths ranging from 7,000 to 20,000 (thousands killed in other places except the earthquake).
What seems to distinguish the newly recognized subset of rock avalanches is the role of various factors in lubrication of relatively low angle glacial foundations. While the typical snow avalanche fell from 30 to 45 degrees slopes, many of the collapsed glacier slices analyzed by Kääb and colleagues sat on milder slopes from 10 to 20 degrees. In the main events shown in the figure below:
- down: Flat Creek, Alaska (2013 and 2015)
- Chile: Aparejo (1980) and Tinguguarica (1994 and 2007)
- Argentina: Leñas (2007)
- Russia/Georgia Border area: Devdorak (18th and 19th centuries) and Korka (1902 and 2002)
- Tajikistan: Rasht (2017 and 2019)
- Tibet: ARU (2016), Amney Machen (2004, 2007, 2016 and 2019), Sedongpu (2018) and Zelunglung (1950, 1968 and 1984)
- Mongolia:tsambaragav (1988)
The deadliest such glacial detachment in recent years was the collapse of part of Kolka Glacier, in the Caucasus Mountains near the Russia-Georgia border, on September 20, 2002. A volume of rock similar to that atop Birch Glacier helped force a section of Kolka Glacier some 40 times larger than the lower Birch Glacier (close to 130 million cubic meters) to detach. As it raced from a 13-degree slope and pushed downstream for more than 16 kilometers (10 miles), the flow of rocks and ice buried a village, killing at least 125 people.
Compared to this and other analyses, the lower birch glacier moved away from the steep slope – about 28 degrees.
“This does not mean that the Birch Glacier case is completely different from the case we described in 2021!” lead author Kääb said in an email. “We face the scope of the same processes that are combined in different ways in a single disaster. For all practical means, the results are very same: a highly mobile large-capacity avalanche including rocks, ice, snow, water, mud, mud, mud and anything that occupies on the road.”
Climate link Leaving to the glacier
As Kääb and colleagues analyzed, the tendrils of warming climates appear to stare at the glaciers’ disengagement in several ways. When melting or high altitude rainfall occurs in places that are rare or non-existent in modern times, it increases the instability of rock and glacier structures. Damage to permafrost can help damage the rock walls above the glacier. And in the birch glacier case, heavy rock sediments seem likely to increase pressure near the bottom of the glacier and cause melting of the foundation and sudden advancement and/or collapse.
Kääb said four years since the 2021 paper 1749485486 We are more convinced that climate change can contribute to glacier detachments and rocky ice avalanches. For individual cases, it is difficult to prove that climate change is the main cause. But it is also clear that climate change can promote these events in different ways. ”
Thanks to intensive monitoring in advance and careful reviews in the days before the collapse, the Birch Glacier case may prove to be a gold mine for research and a model for life-saving alerts.
“Switzerland is lucky that once the severity of this situation is obvious, there are resources to build a wide range of monitoring systems. Few mountainous regions in the world have the same capabilities,” said Jane Walden, a doctoral student at Eth Zurich and WSL Sion in Zurich in an email.
As for technology, “ground-based radar systems are the best choice for monitoring mobile slopes or glacier movements because they work in harsh weather, but they are also very expensive and end up struggling with very fast movements.” GPS sensors and other simpler, lower materials may be more suitable for hard-to-reach areas, but they can also be fragile: A type of such GPS device was destroyed in the Nesthorn Mountain before the birth glacier collapsed.
Mylène Jacquemart, a glacologist at Eth and WSL Sion in Zurich, is one of the people who have been jointly analyzing rock ice avalanches. She noted that there is an urgent need to understand the multi-layered thermal structures within the glaciers, which may lead to acceleration and detachment.
“There is a portion based on cold ice (freezing to the bed without liquid water), which comes from warm ice (below the point of pressure melting and usually present liquid water), which can lead to high English water pressure and can lead to large outbreak events, although more research is needed to determine how the heat state is associated with blue breasts,” he said.
She added that in terms of slope-related hazards, “we have seen an increase in rock landfall and landslides in previous glacier areas, so it is important to understand how the rapidly changing ice circle environment affects the stability of the adjacent rock slopes of the glacier and what factors may cause Slope slope of DeStabilized or fail or fail.”
The lower birch glacier has now disappeared, and the valley below looks safe from the rocky ice fall for the time being. But even after the glacier collapse, areas near the Kolkata glacier, including areas near the Kolkata glacier, may not be in trouble.
“Reloading is definitely a problem,” Kabu warned. “The only advantage we have now is that we know that these glaciers have the potential to separate. It's important that these events will not be forgotten.”
Jeff Masters contributed to this article.
Repost our articles for free under the Creative Commons license, online or in print.
