There are only a few places in the world where glaciers terminate on land in the form of an ice cliff. Such vertical ice walls are produced quite often by ice shields running out into the sea as a result of glacier calving – i.e. large chunks of ice breaking away. On land, however, the glacier needs to find very specific conditions to produce ice walls that show long-term stability. The majority of glaciers run out in shallower ice tongues, as typically found in the Alps, for example. The rare land-terminating ice cliffs exist only at the summit of Mount Kilimanjaro, in the dry valleys of Antarctica, and in northwest Greenland and the Canadian Arctic.
In a recently launched FWF-funded project, glaciologists Rainer Prinz of the University of Innsbruck and Jakob Abermann of the University of Graz want to study the ice walls in Greenland in more detail. The target of their research is the Red Rock ice cliff, reaching heights of up to 25 meters, which is found on the Nunatarssuaq ice cap in the northern part of Avanersuaq. This location holds two great advantages for the researchers. Firstly, it is the only ice cliff occurrence on Greenland that was already extensively studied in the 1950s and 1960s, at that time by U.S. researchers. Secondly, the location of the ice formations helps reduce the logistical effort of the expeditions, as it can be reached by a 30-minute helicopter flight from the U.S. Armed Forces’ Pituffik Space Base.
“The idea for the project came up many years ago during research on the glaciers at the summit of Mount Kilimanjaro. A first opportunity for investigations in Greenland arose in 2017, when we were already able to equip a smaller expedition to the Red Rock ice cliff,” Rainer Prinz looks back. “Now we want to deepen our research during two longer stays in Greenland. This will not only involve more detailed research into the factors influencing further development of the glaciers. We also want to use the formations, which are particularly sensitive to changes in environmental factors, as a tool for better understanding the local climate in Greenland in the context of global warming.”
Glaciers in the balance
If an ice cliff is to remain stable on land over time, it must have a stable mass balance, which means that newly created ice and the glacier movement have to be in balance with all melting and ablation processes that reduce the ice mass. External factors of influence, including air and ice temperature, humidity and radiation input, must not be too variable. The fact that ice cliffs occur in generally dry and very cold climates suggest that they are very sensitive to factors controlled by humidity, such as cloud cover and precipitation, which in turn have an effect on radiation fluxes.
In a study published by Prinz et al. in the Journal of Glaciology after the 2017 expedition, the researcher showed that in addition to a general trend of the ice layer thinning, there were also repeated advances of the ice cliff. The team wants to elucidate this circumstance, which initially seems contradictory, by investigating the various influencing factors.
In the context of the first expedition, which is to take place in 2024, the ice cliff will be precisely surveyed. The Austrian research teams also want to install sturdy instruments and weather stations able to survive the polar night. Imagery taken by camera drones during the expedition will permit the computation of accurate surface models of the cliff’s geometry. Towards the end of the project, these measurements will be repeated during a second trip to Greenland.
The researchers' on-site measurements will be combined with satellite data, further measurements from the Danish Programme for Monitoring of the Greenland Ice Sheet PROMICE , and new high-resolution metrological data produced by the European Copernicus Earth observation program. Among other things, these findings will be used to optimize energy, mass balance, and flow models of the glaciers that will lead to a better understanding of energy flows – both on the glacier surface and on the vertical cliff – and help to identify sensitivities to environmental factors.
Identifying climate signals
If the glaciologists’ models built on the basis of these evaluations can provide a good fit for the behavior of the ice cliffs, they will be able to gain important insights. “Changing climate signals very quickly affect glacier balance,” Prinz explains. “If we understand the way in which the ice reacts to changes in environmental factors, we can draw conclusions about a current development of the local climate.”
Climate researchers assume that in the course of global warming the Arctic will not only become warmer overall, but also more humid. The changes in the sensitive ice cliffs could serve as a climate sensor and an early warning system for the Arctic region, which is particularly relevant in the context of global climate development. This is because the cliff changes allow significant changes in the Arctic climate to be detected much more quickly and easily than complex climate modeling. Evaluating such models can be very time-consuming and small-scale phenomena can only be captured in simplified form or not at all. “We want to calibrate the ice cliffs as an instrument that gives us an immediate insight into the development of the Greenland climate,” Prinz concludes.
Rainer Prinz sstudied geography and atmospheric sciences at the University of Innsbruck, where he heads the Hintereisferneroutdoor glaciology lab. In his doctoral thesis, he showed that glaciers in the tropics are particularly sensitive to variations in precipitation and humidity and can be calibrated as measuring instruments for climate reconstruction. The idea for the Ice Cliffs in Greenland (LATTICE) project (2023 – 2027) arose during Prinz's postdoctoral stay at the University of Graz. The project has been awarded EUR 399,000 in funding by the Austrian Science Fund FWF.
o Steiner J. F., Buri P., Abermann J., Prinz R., Nicholson L.: Steep ice – progress and future challenges in research on ice cliffs, in: Annals of Glaciology 2023
o Abermann J., Steiner J. F., Prinz R. et al.: The Red Rock ice cliff revisited –six decades of frontal, mass and area changes in the Nunatarssuaq area, Northwest Greenland, in: Journal of Glaciology, 2020