While rising temperatures in the Arctic are increasing glacier mass loss by extending the melt season, they may also lead to an increase in snow accumulation as warmer air can carry more moisture. While the first effect dominates overall and at lower elevations, enhanced snow accumulation might locally compensate the mass loss, at higher elevations in particular. On Freya Glacier in NE-Greenland above average winter precipitation 2018 combined with widespread avalanche activity slowed down the mass loss and even led to a positive mass balance within an 8-years measurement period 2013 – 2021.

Freya glacial monitoring, drone flight over glacier. (© Bernhard Hynek)

Location of Freya Glacier (74.38°N, 20.82°E) on Clavering Island in Northeast Greenland. (from GoogleMaps)

Land ice in Greenland is usually divided into the vast Greenland Ice sheet in the interior and more than 20.000 peripheral glaciers on the margins of the island. While the peripheral glaciers comprise only 4% of the total ice covered area of Greenland, their recent contribution to mass loss from Greenland is disproportionately high (11 %), as smaller glaciers react faster to climatic changes. But unlike in the Alps only very few of these glaciers (currently 6) are permanently monitored by in situ measurements. Two of them are situated in the Northeast Greenland National Park, the largest national park of the world, in close vicinity of the research station Zackenberg. Monitoring of Freya Glacier, a small coastal mountain glacier and A. P. Olsen Ice Cap was initiated within the last International Polar Year in 2007/08. Since then mass balance measurements are carried out in close cooperation by Danish and Austrian glaciologists. To better understand the interrelation between climatic changes and glacier changes we measure the surface mass balance on several locations as well as atmospheric parameters at a weather station on the glacier.

Picture of Freya Glacier and its surrounding ridges in August 2008. (© Bernhard Hynek)

However, these annual measurements provide mass changes at a specific location on the glacier, and by extrapolating the values to the whole glacier systematic uncertainties might be introduced. Therefore, volume change measurements in a decadal frequency are recommended to get a more accurate result and to eliminate a possible bias. Travel restrictions due to the pandemic made it impossible to visit the glacier in spring 2020 and 2021, so we took the opportunity to visit the glacier again in summer 2021. We used a drone to survey the glacier surface, and calculated the volume since the last survey in 2013.

As avalanches are not only linked to climate, but also to local topography, it is important to separate the effect of avalanches on the mass balance from other processes. We already assumed that Freya Glacier is prone to receive avalanches from the steep slopes on both sides of the glacier, but we were not able to quantify the mass input of these avalanches. In April 2018 it was possible to reach the glacier with a snow scooter and to conduct a detailed snow survey with a radar. Two months before the survey, 1.5 m of snow had been fallen within 5 days, and several large avalanches went down on the glacier surface. We found avalanche deposits on more than 30% of the glacier area, with snow depths up to 15 m. The mean snow depth on the glacier was 4.8 m, the overall contribution of snow avalanches was more than 0.8 m which is close to 20% of the total winter mass balance.