The Alps, the majestic mountain range that stretches across eight European countries, are not only a source of awe and wonder for millions of people, but also a treasure trove of scientific information.
By studying the landforms and erosion rates of these mountains, researchers can uncover the history of climate change and its impact on the Earth's surface.
Moreover, they can also explore the possible scenarios of the future, as the Alps continue to evolve under the influence of natural and human factors.
The Legacy of the Ice Age
Marco Meyer/Unsplash
One of the most striking features of the Alps is the presence of glaciers, the massive sheets of ice that carve and sculpt the landscape.
Glaciers are formed by the accumulation and compaction of snow over thousands of years, and they move slowly downhill due to gravity.
As they move, they erode the underlying rock and leave behind distinctive landforms, such as U-shaped valleys, moraines, and cirques.
The Alps have been glaciated several times during the Quaternary period, the last 2.6 million years of Earth's history, which was marked by repeated cycles of glacial and interglacial periods.
The most recent glacial period, known as the Last Glacial Maximum, occurred about 20,000 years ago, when the glaciers covered about 60% of the Alps. Since then, the climate has warmed and the glaciers have retreated, exposing new areas of rock to erosion.
One of the places where this process can be observed is the Rothorn Glacier in Hungerli Valley, Switzerland, a bowl-shaped depression cirque glacier and the study site of rockwall erosion.
Researchers from Utrecht University, Netherlands, have been studying this glacier and its surroundings for decades, using various methods such as field measurements, laboratory experiments, and numerical modeling.
They have reconstructed the glacial retreat history of the valley and calculated the erosion rates of the rockwalls, the steep slopes of bedrock that border the glacier.
Their findings, published in the journal Earth and Planetary Science Letters, reveal that the erosion rates of the rockwalls have declined significantly in the last 10,000 years, compared to the earlier stages of the Holocene, the current interglacial period.
They attribute this decline to the reduced glacial load and debuttressing, which means that the removal of the ice reduces the pressure and support on the rockwalls, making them less prone to fracture and collapse.
However, the erosion rates of the rockwalls are not only influenced by the glacial history, but also by the current and future climate conditions.
One of the factors that affects the stability of the rockwalls is the presence of permafrost, the permanently frozen layer of soil or rock that lies below the surface.
Permafrost acts as a glue that holds the rock fragments together, but it can also cause damage when it thaws and refreezes, creating cracks and fissures.
Permafrost is sensitive to changes in temperature, and it is expected to decline in the Alps as the climate warms. According to a recent study, the Alpine permafrost could lose up to 90% of its volume by the end of the century under a high-emission scenario.
This could have serious consequences for the rockwalls, as they would become more vulnerable to erosion and rockfall events, which pose a threat to the infrastructure and the people living in the valleys.
Another factor that affects the erosion rates of the rockwalls is the frequency and intensity of precipitation, which can trigger landslides and debris flows.
Precipitation patterns are also likely to change in the Alps due to climate change, with more extreme events such as heavy rainstorms and droughts.
These events could increase the erosion and sediment transport in the Alps, altering the landscape and the water quality.
The Alps are a dynamic and complex system, where the interactions between climate, tectonics, and erosion shape the topography and the environment.
By studying the past and present changes in the Alps, researchers can gain insights into the future of this region and its implications for the society and the biosphere.
The Alps are not only a natural wonder, but also a natural laboratory, where the secrets of the past and the future are revealed.
