17.07.2023: Observations Oberaar glacier (Bernese Alps)

The Oberaar glacier has lost a lot of mass since our visit on 2.7.2022.

The glacier gate appeared smaller than on 2.7.2022. The pieces of ice lying in the stream bed and the crevasses on the left above the glacier gate show that the glacier gate is constantly changing. It is continuously moving towards the west (to the right in the photo).

On the south side of the glacier, east of the glacier gate at the foot of the slopes, there is still a lot of dead ice. Some of this glacier ice is covered with debris and boulders, some of the dead ice is bare and directly exposed to the warm air. Currently, a horizontal layer of debris and boulders embedded in the ice can be seen on a bare surface (see photo on the right of 1).

The glacier tongue shows numerous signs of decay such as holes and tunnels. As it looks, the Oberaar glacier will continue to lose length and mass.

The eastern collapse structure has a length of 200m and a width of about 150m (source: measurement on map.admin.ch). It has two centres. The outer radial fissures enclose both centres. It was not clear to us whether the two centres reach the glacier bed or not.

This photo shows a bird's eye view of the eastern collapse structure from the west.

The western collapse structure has a diameter of about 150m (source: measurement on map.admin.ch) and has a centre.

During the processing of the drone panorama photos, we discovered radial fissures that indicate the formation of another collapse structure.
Legend:
1) Edge of the western collapse structure
2) Centre of the radial crevasses, which indicate the formation of another collapse structure.
3) The meltwater from the small glacier on the Scheuchzerhorn has carved several channels into the ice, which is covered with a lot of debris. The radial crevasses at 2) are probably related to the meltwater channels at 3).
The collapse structures are clearly visible in the drone panorama photos from 17 July 2023.
The section on the signs of another collapse structure was added on 29.12.2023.

Around a small stream flowing laterally into the glacier, an approx. 4m high tunnel (= meltwater channel) has formed. From the entrance it could be seen that after about 30 metres it opens into a meltwater channel running in the longitudinal direction of the glacier.

Legend:
1) Part of the meltwater, flows under the dead ice in the area of the glacier gate.
2) Here the meltwater flows into the young Oberaarbach, which disappears under the dead ice at 1).

In the afternoon, the Oberaarbach had a lot of water a little below the glacier.

A red pillar has been installed not far from the glacier gate of the Oberaar glacier. This is so that visitors from all over the world can be sure that they are at the source of the Aare and not at the gate of the Oberaargletscher, which is melting away due to climate change.
According to the official national maps, the Oberaarbach, not the Aare, flows out of the Oberaar glacier.
Tourism took over the area in front of the glacier gate before the first pioneer plants could gain a foothold.

Glacial polish was drilled for the mounting of the column. Glacial polish, which lay under the glacier ice for centuries (possibly millennia) and was shaped and polished by ice, stones and sand. The gate of the Oberaar glacier will move further west as a result of the glacier melt in the coming years. The column will therefore have to be mounted further west in about 2-3 years. For this purpose, glacier drift will probably be drilled again.
The Oberaar glacier is located in the 'UNESCO World Heritage Jungfrau Aletsch' as well as in the 'Grimsel' nature reserve and is part of the 'Federal Inventory of Landscapes and Natural Monuments of National Importance BLN' (No. 1507, sub-area 'High Mountain Landscape').