Permafrost soils: If the permafrost soil thaws, the world will feel it | BR.de

Around one sixth of the total surface of the earth is considered a permafrost area. It is characterized by the fact that the ground there is permanently frozen for at least two years. Often the cold in such regions has been buried in the ground for thousands of years, so that the permafrost can reach a depth of several hundred meters, in extreme cases around one and a half kilometers. Permafrost consists of rocks, sediments, earth – and varying amounts of ice. Permafrost soils are found in the cold climates of high latitudes and in high mountains. You can find the special soil in Alaska, Scandinavia, Russia, Canada, China and Greenland, but also in Germany: on the Zugspitze.

If permafrost soils soften, it affects the world

Thawing permafrost soils have far-reaching consequences: If they soften, this affects the global climate and entire ecosystems, but also the landscape, infrastructure, economy and local population: greenhouse gases are released that accelerate global warming. Permafrost is actually impermeable to water – when it melts, the water lying above it can seep away and lakes and wetlands dry up. The ground becomes unstable and shifts, coasts collapse, houses, bridges and lines collapse. Landslides and rockfalls pose an additional risk to the population.

Permafrost - what is it?  |  Image: Alfred Wegener Institute, Helmholtz Center for Polar and Marine Research (via YouTube)

Permafrost – what is it?

Greenhouse gases are escaping from thawing permafrost soils

Permafrost carbon feedback

Permafrost heats up and releases carbon dioxide and methane. The greenhouse gases contribute to global warming. And that in turn means that the permafrost soil continues to thaw and release even more greenhouse gases into the atmosphere. A self-sustaining and even accelerating system. The process is also called “permafrost carbon feedback”.

You can imagine permafrost ground like a huge freezer in the ground. The remains of plants and animals have been preserved in it for thousands of years. Usually it’s frozen and solid like cement. However, with global warming, temperatures also rise underground. When the organic, carbonaceous material thaws in the soil, it is broken down by microorganisms. Carbon dioxide (CO2) and methane are released, which as greenhouse gases intensify the greenhouse effect, drive the warming of the atmosphere and thus increase the global temperature. Methane is 25 times as powerful as carbon dioxide. That is why there is often talk of the threatening “methane bomb” from permafrost soils. According to the Alfred Wegener Institute (AWI), it is currently assumed that the organic material of the permafrost soil contains up to 1,500 gigatons of carbon – almost twice as much as the current amount in our atmosphere.

“Methane only occurs in low concentrations, but it is particularly dangerous because its warming potential is many times higher than that of CO2”

. Nikolaus Froitzheim, geologist, Institute for Geosciences, University of Bonn

Thawing permafrost causes the temperature to rise worldwide

A global comparative study by the international permafrost network GTN-P (Global Terrestrial Network for Permafrost), in which the Alfred Wegener Institute (AWI) was also significantly involved, showed that in all areas with permafrost worldwide the temperature in more than ten meters depth increased by an average of 0.3 degrees Celsius between 2007 and 2016. The Arctic was observed as well as the Antarctic, but also the high mountains of Central Asia and even the Alps. In their study, the scientists assume that the greenhouse gases from thawing permafrost soils could raise the global temperature by a further 0.13 to 0.27 degrees Celsius by the year 2100.

Forecast: Thawing permafrost will increase temperature by 0.2 degrees by 2100

Most previous projections assume that the greenhouse gases from thawing permafrost will contribute around 0.2 degrees Celsius to global warming by 2100. By then, the permafrost will probably even be responsible for a higher value – and not just because climate change is accelerating ever more. For the model calculations, mostly only the emission values ​​that arise when plant and animal remains decompose in the permafrost soils have so far mostly been used. It is now known, however, that greenhouse gases in thawing permafrost areas can also escape from stone soils – and that these values ​​still have to be taken into account in the forecasts.

Permafrost soils release environmental toxins such as mercury

However, permafrost soils that become warmer as a result of climate change do not only affect the temperature and thus, in turn, climate change. Environmental toxins are also stored in the permafrost – for example large amounts of mercury. In the gaseous state, they reach the poles with air currents, land there on the ground and freeze. If the soil thaws, the toxins enter the environment and the food chain.

Danger to streets and houses: If the permafrost thaws, the ground sags

When the permafrost thaws, the local people literally lose their feet: especially in the Arctic, houses, roads, airports and pipelines have been built on the permafrost. Worldwide, more than a thousand settlements and cities with a total of around five million people are built on frozen arctic soil, says Mathias Ulrich, geographer at the University of Leipzig. “Forecasts assume that in 30 years 42 percent of these settlements will be free of permafrost.” And when the ground warms up, it can sag and sweep away the buildings.

Thawed permafrost: Damage to up to 50 percent of the infrastructure

An international research group around Jan Hjort from the University of Oulu (Finland) published figures on this problem in the specialist journal “Nature Reviews Earth & Environment”: According to the calculations, between 30 and 50 percent of the buildings and infrastructure facilities in the northern permafrost areas are likely to be threatened by damage of various degrees of severity by 2050. The researchers identified the endangered areas with the help of statistical analyzes based on geospatial data. Canada, Alaska, Greenland, the plateau of Tibet and Russia are particularly affected.

In Russia in particular, the largest country in the world in terms of area, the slow thawing of permafrost is likely to become a major problem. Because almost two thirds of the floor area is permanently frozen there. The forecast of the research group: The repair costs for permafrost-related damage to the Russian road network for the years 2020 to 2050 will amount to around seven billion US dollars.

Building protection: Houses are built on stilts

As in many permafrost regions, in the northernmost city in the world, the Russian city of Norilsk, the houses are on stilts ten to 30 meters long. This is to prevent buildings from collapsing in the event of temperature fluctuations. But when it gets warmer and warmer, the ground sinks deeper and deeper: If the ground thaws three to five meters into the depth, it can sink up to a meter, reports engineer Ali Kerimow, director of the research and production company Fundament. Then the piles can no longer save the houses from collapsing. It becomes particularly dangerous when pipelines or tanks are damaged and fuel seeps into the ground.

Protection for the infrastructure: solutions for thawing permafrost soils

In order to protect the infrastructure and thus also the population in permafrost areas, new ideas and developments are required. Engineer Kerimow advocates regular monitoring of frozen soils: “The monitoring system should be set up in such a way that changes in the soil temperature and a possible lower load-bearing capacity of the foundation can be predicted five to ten years in advance.” Then there would be enough time to find ways and means to implement suitable measures for more security in good time.

Only small buildings left on permafrost

Foundations and floors are already artificially cooled in many places so that houses do not collapse on melting permafrost. The experts use so-called thermal stabilizers. Research is being carried out into new materials for foundations that can cope better with temperature fluctuations. Since damage and thus dangers are inevitable, no new buildings should be erected in permafrost areas without such novel approaches. Norilsk has already done without new high-rise buildings: since 2002, only smaller buildings have been built on the thawing ground.

Sources and further information on permafrost

You can find more background on permafrost soils here:

broadcasts:

  • nano | Knowledge. Good question: permafrost. December 2nd, 2020, 10:45 am, ARD alpha.
  • nano | Knowledge. Heat in Svalbard – When the Arctic thaws. September 15, 2020, 5:45 pm, ARD alpha.

Reference-www.br.de

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