Publication Date September 28, 2018

Global Warming Is Destabilizing Mountain Slopes, Creating Landslide Risks

Storms have triggered landslides in the Alps that have sent mud and debris pouring into villages. Bondo, in the Swiss Alps, has been hit more than once in recent years. The video below shows the destruction from 2017. Photo: Miguel Medina, AFP/Getty Images

It's not just the atmosphere and the oceans that are heating up. An ever-denser blanket of greenhouse gases is also sending warmer air and water deeper into the planet's rocky bones.

In the mountains of Switzerland, scientists have measured startling temperature increases, with jumps of as much as half a degree Celsius in just a decade 20 feet deep into the rocks. On Svalbard, an Arctic island north of Norway, similar warming has been measured more than 100 feet deep in the permafrost.

Tracking these changes is critical to assessing growing threats to people, said Bjørn Samset, research director at the CICERO climate research center in Oslo.

The warming, combined with other climate effects like extreme rainfall, is speeding up some basic geological processes. Softer rocks and soils that used to stay frozen most of the year, like permafrost, are thawing and eroding faster. Seemingly monolithic slabs of solid granite are peeling off mountainsides like the layers of an onion. And powerful rock glaciers—wide swaths of slow-moving ice and rock rubble that can pulverize granite—are speeding up, in one case from 40 feet per year to 226 feet per year.


Thawing Permafrost Can Destabilize the Land

The effects of heat-trapping pollution are showing up in the high peaks of the Alps. In Austria, a historic mountain weather and climate observatorynearly tumbled from the craggy summit of the Sonnblick peak as global warming thawed permafrost and melted ice that had held the rocks together.

A team of scientists monitoring the Swiss peaks above Andermatt say they've detected some warming as deep as 300 feet into the rocks. In a few places, some giant rock slabs have moved more than 4 feet in a year, a possible warning sign of a large collapse.

Continued warming and the thawing of permafrost also increases the chances for big mudslides and debris flows. As more and more of the previously frozen soil thaws, it can easily be set into motion by rain, said climate scientist Ketil Isaksen of the Norwegian Meteorological Institute.