Changes in glacial ice thickness are central to modeling the effects of climate change in high-altitude mountain areas. They allow a wide range of predictions, from regional water supply to the threat of mudslides in high mountain valleys. The more accurately the ice thickness can be determined, the more accurately such scenarios can be predicted.
Researchers at the Institute for Interdisciplinary Mountain Research of the Austrian Academy of Sciences (OeAW) have achieved an important result in this field. Using a new method, they have not only confirmed glacial retreat, which has been observed globally, but also calculated more precise results for the entire ice mass in Austria’s high-altitude mountains. This research success, which was achieved within the framework of the project "FutureLakes" funded by the Academy, has now been published in the current issue of the journal "Frontiers in Earth Science".
"Until now, the ice mass has been estimated primarily on the basis of the glacial area", explains OeAW mountain researcher Kay Helfricht. "But we wanted to find out how thick the ice layer is at different points of a glacier." The researchers used the so-called Austrian Glacier Inventories, including glacier boundaries and altitude models based on aerial photographs and laser scanning images. They combined these with ice thickness measurements of 58 Austrian glaciers to develop a model calculation. This made it possible to determine, as realistically as possible, the ice thickness under the respective topographical conditions for all glaciers in Austria.
Using this method, the researchers were not only able to make more precise statements about the current distribution of the ice mass, but also about changes over time. "In 2006, the total volume of glaciers in Austria was just under 15.9 km³. This would be enough to cover the whole of Austria with 16 centimeters of water. But by 2016, Austria's glaciers had already lost a fifth of their ice mass", Helfricht says. The new approach thus confirms the average loss of glacial ice of around one meter of ice thickness per year.
At the same time, the new modeling approach reveals large regional differences in the global phenomenon of glacial retreat. Especially on glaciers with an ice surface of less than one square kilometer, such as the Stubacher Sonnblickkees or the Brandner Glacier, there has been, depending on topographical conditions, a comparatively strong decline in the remaining ice mass. These findings open up new opportunities for more accurate assessments of regional and local climate change impacts; in terms of hydrology, natural hazards and effects on the economy.
In addition, the results already obtained provide new insight into the possible future course of glacial retreat in Austria: "In the next two to three decades, much of the ice thickness, rather than the surface area, will be lost, as the large glaciers in particular still have relatively thick tongues", says Helfricht. But thereafter, according to the mountain researcher's sobering outlook, if the conditions do not change, the loss of surface area will be even faster.