On 5. August 2024, we were able to make the following observations on the Oberaar Glacier:
Oberaar Glacier
Oberaargletscher on 5. August 2024.
A larger part of the glacier was covered with snow than during the last visit on 17. July 2024. After several Saharan dust events in spring and summer 2024, the snow was covered with Saharan dust, which can be easily recognized by the yellow-brownish color of the snow. The Saharan dust accelerates the melting of the protective layer of snow.
Oberaargletscher and glacier gate on 5. August 2024.
In the area of the glacier terminus, the Oberaar Glacier has changed considerably within a year.
Glacier gate
Glacier gate of the Oberaar Glacier on 5. August 2024.
On 5. August 2024, the
glacier gate was relatively small and partially filled with snow.
Dead ice
Dead ice on the south side of the Oberaar Glacier on 4. August 2024.
On the south side of the glacier, there is still a lot of dead ice at the foot of the slopes to the east of the glacier gate. 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.
Signs of decay
Signs of decay on the glacier terminus on 5. August 2024.
The glacier terminus shows numerous signs of decay such as holes and tunnels. Unless a miracle occurs, the tongue of the Oberaar Glacier will continue to retreat rapidly.
Signs of decay on the glacier terminus on 5. August 2024.
Collapse structures
The collapse structures, which are located approx. 300 - 350m west of the glacier gate, have changed considerably within a year.
Collapse structures in the Oberaar Glacier from the east on 5. August 2024.
Legend:
1) The eastern
collapse structure has opened up. At its bottom, a lot of meltwater flows in a stream bed.
2) The middle collapse structure has partially opened.
3) The ceiling of the western collapse structure has lowered further, but has not yet opened.
View of the eastern collapse structure in the Oberaar Glacier from the east on 5. August 2024.
The meltwater flows in a stream through the gate visible in the photo into the open collapse structure.
Detailed view of the gate in the eastern collapse structure in the Oberaar Glacier from the east on 5. August 2024.
A considerable amount of meltwater flows through the gate. The gate will probably not last long.
Eastern collapse structure in the Oberaar Glacier from the west on 5. August 2024.
The meltwater flows out of the open meltwater channel through two large meltwater channels. The photo shows the portal of the northern meltwater channel. The pieces of ice lying on the ground indicate the progressive decay of the collapse structure and the meltwater channel.
Eastern collapse structure in the Oberaar Glacier from the west on 5. August 2024.
This photo shows the two arms through which the meltwater leaves the collapse structure. As the Oberaar Glacier is no longer particularly wide at this point, the situation will probably not be very pleasing in a year's time.
Western collapse structure from the east. Aerial view from 5. August 2024.
Melt water
Outflow of meltwater below the glacier gate on 5. August 2024 at 8:15 a.m.
Outflow of meltwater below the glacier gate on 5. August 2024 at 14:15.
On 5. August 2024, the outflow of meltwater following the
daily course could be observed on the Oberaar Glacier. During the cooler night, less snow and ice melts than during the day at higher temperatures and in direct sunlight. The level of the glacier stream reacts to this effect with a delay.
Erosion on the lateral moraines
The melting of the Oberaar glacier is having an impact on the lateral moraines. These are exposed to increased erosion due to the melting of the supporting glacier ice and the thawing of the permafrost.
The photos below show some of the effects on the southern lateral moraine from east to west.
Breakthrough of the southern moraine of the Oberaar Glacier on 5. August 2024.
Legend:
1) A few years ago, meltwater from the glacier on the northern flank of the Löffelhorn broke through the southern moraine, possibly with the support of heavy precipitation events. Since then, an impressive erosion trench and a large debris cone have formed. The cone of debris is so large that it has pushed the Oberaarbach to the north.
2) The cone of debris mentioned above.
Erosion gullies and debris cones on 5. August 2024.
Legend:
1) Erosion gullies (possibly even erosion trenches) have formed in several places. Meltwater, (heavy) precipitation and thawing permafrost are probably the reasons.
2) Boulders, debris and sand were deposited partly on the dead ice and partly in a debris cone. This photo also shows how the Oberaarbach was pushed northwards. Bit by bit, the Oberaarbach is eroding the debris cone and washing sand and debris into the nearby Oberaarsee.
Global warming means that more bed load and sand is being washed into the reservoirs. This has a negative impact on the capacity of the reservoirs.
Runoff of meltwater in the area of the glacier gate on 5. August 2024.
Legend:
See previous photo.
Slipped part of a moraine on 5. August 2024.
Legend:
1) Over a width of 140m (source: measurement on map.admin.ch), the entire moraine has slipped. In this case, dwindling permafrost may have played a role.
2 & 3) A debris flow broke loose in the area of 2), which only came to a halt in the area of 3) a little behind the glacier gate. The deposited debris covers the glacier ice, which delays the melting of the ice.
Meteo
Temperature: 22° at 1 pm on the glacier.
Zero degree limit: 4300m ü.M.,
the 7 previous days between 3700 and 4500m above sea level, on average at 4220m above sea level.
Published:
18.08.2024