When the ground remains frozen a whole calendar year we call it permafrost. In Norway, permafrost is most common in mountain terrain and areas upland, and just a small change in permafrost can have serious consequences for the mountain landscape and neighboring areas.
The Department of Geosciences at the University of Oslo has developed a strong expertise when it comes to permafrost and Professor Bernd Etzelmuller explains why the decrease in permafrost is worrying.
Permafrost glues the landscape together
If you get high enough in the Norwegian mountain terrain the ground will stay frozen the year through.
Norway is a country full of mountains. However, the presence of permafrost is decided by the local climate.
In southern Norway the permafrost boundary varies from 1 600 meters above sea level in the west to 1 300 meters in the east. In Northern Norway we see a lower boundary with approximately 900 meters above sea level in the west and 400 meters in eastern parts of Finnmark.
Sporadically, in some part of Finnmark you might find permafrost at sea level where permafrost is bound to marshlands, so called palses.
Where we find permafrost the ice will sculpture and shape the surrounding landscape and in the mountains it will act as glue: It keeps the ground stable and the terrain together.
– When water transforms into ice it swells and the other way around. Consequently, in areas where freezing and melting occurs regularly, cracks will develop and expand, says Etzelmuller.
These cracks can make the mountainside unstable.
– When water freezes to ice inside the crevice it becomes a part of the mountain. In many ways the ice glues the mountain together. If we see a temperature increase, ice will disappear and the mountain will rapidly become unstable. When the foundation of ice is gone the risk of landslides will increase, Etzelmuller explains.
Observations made by the Norwegian Meteorological Institute and the Department of Geosciences reveal that the ground temperature in Norway on the whole has increased by a whole degree.
Other observations also show that the permafrost is on the decline in many areas.
– We have several ways of making these observations. Either a group of scientist travel and make their own observations. Or, additionally, we make measurements and observations from planes and drones. At Finnmarksvidda (The Finnmark plateau) in Northern Norway observations show that the permafrost in marshlands many places have been reduced with as much as 50 percent since the 50s. This is a substantial decrease, says Etzelmuller.
A tsunami waiting to happen
That the permafrost is on the decrease has many consequences.
– As I mentioned the risk of landslides will increase. Initially, this is not that dangerous. Most mountains in Norway are far away from important infrastructure and populated areas. However, there are mountains like Nordnes in Lyngenfjorden and the significantly more famous "Mannen". In these places a lot can happen. Naturally, where landslides may reach populated areas and infrastructure they can cause a lot of damage. That is why NVE (Norwegian Water Resources and Energy Directorate) has a continuous surveillance of these areas if they are known to them.
The melting of permafrost can also have more substantial catastrophic consequences. A mountain crag may fall into the sea and cause a gigantic wave, a tsunami.
This could wipe out whole communities, something that actually happened when a tsunami hit Tafjord in 1934. What happened was that a 3-4 million cubic meter large mountain crag crashed into the fjord from an altitude of 750 meters.
- Yes, this can happen today. Nordnes in Lyngen have a large area that is unstable, and there is also a mountain with deep ice filled crevices. If the permafrost continues to melt inside the crevices the mountain will become increasingly unstable and parts of the mountain might split and fall. Sooner or later this will happen. And if climate change continues, this will become reality other places in Norway too. Climate change can put local communities and infrastructure under substantial pressure, says Etzelmuller.
Adds to climate change
The continuous melting of permafrost will simultaneously increase the emissions of greenhouse gasses. The frozen ground conserves CO2 and other gasses especially in marshlands where a lot of organic material from plants are located. If the ice melts the gasses will be released and contribute to the greenhouse effect.
– Decomposed organic material is stored inside the permafrost. When it melts greenhouse gasses will be released into the atmosphere. If the temperature continues to increase this is something we have to include in the climate calculus, Etzelmuller claims.