The PAGE21 project has now been officially closed. The four years of research came to an end on October 31 2015, leaving only...
PAGE21 project was featured in a plenary session "Permafrost in the 21st century" at the 2015 Arctic Circle conference in Reykjavik,...
Blog Tundra Stories: Permafrost - What is it?
Tuesday 7 August 2012
Permafrost - in German, graphics: Alfred Wegener InstituteAfter we wrote the last post, on what sensitive ground we find ourselves, I would like to write some background to it. Those of you who associate with permafrost "permanent" or "always frozen ground", are quite correct. By definition, permafrost is "ground, soil or rock, including ice or organic material, that remains at or below 0°C for at least two consecutive years."
In Germany, in our homebase, the surface freezes only for short periods of time in the winter, which means that there is almost no permafrost in Germany. But you can find permafrost in the Arctic and Antarctic and in the high mountain areas of the earth.
Even though permafrost is defined as "continous", the ground is not frozen at all depths throughout the year. Over the summer time the top layer of soil oftens thaws because of the positive air temperatures. This layer is called "active layer". The continous frozen condition is actually good, because as long as the ground is frozen, there is very little reformation. About the same way we expect to be home in the freezer. Once the soil thaws, however, many different processes start to take place. With liquid water, all kinds of fabrics and heat are distributed in the soil. The annual freezing and thawing exerts forces on the ground, for example, the shape of the island endemic polygonal tundra.
A very great importance is the process that fits very well with the example of the freezer; a process where the bacteria begin to process the existing carbon in the soil resulting in carbon dioxide and methane. This makes the permafrost a particularly interesting element in the climate system. If the temperature keeps rising due to global warming also in the permafrost regions, it can accelerate the thawing or the permafrost might even completely disappear in certain places. That would result in significant increase in bacteria which in turn would release more carbon stored in the soil in the form of greenhouse gases. A so-called positive feedback.
The actual permafrost is thus below the depth of maximum thawing of the soil in summer. Here on Samoylov it is at about 40 centimeters below the surface. What it means exactly for our work is that we have over 40 centimeters of slush on top of rock hard frozen ground. At greater depths the temperature rises again steadily due to the heat flow from Earth's interior, so that the soil thaws again at a certain depth. How deep the actual permafrost is depends on current average temperatures, but also on the climatic conditions in the past. Here in northern Siberia the partial depth is about one kilometer, which can be explained by the fact that this area was higher than surrounding areas in the last ice age, and was not protected by layer of ice.
I hope we were able to explain you some important basics about the permafrost. But do not worry, the blog will not become an online textbook and in the next posting we will come back to you with some more current expedition news.
Max
To learn more about the basics of permafrost, please take a look at the PAGE21 Fact Sheet no.1
______________________________
Main page of the English translation of the blog "Tundra Stories" can be found here
Original blog in German: http://www.awi.de/de/go/Tundra-Stories
Permafrost - in German, graphics: Alfred Wegener InstituteAfter we wrote the last post, on what sensitive ground we find ourselves, I would like to write some background to it. Those of you who associate with permafrost "permanent" or "always frozen ground", are quite correct. By definition, permafrost is "ground, soil or rock, including ice or organic material, that remains at or below 0°C for at least two consecutive years."In Germany, in our homebase, the surface freezes only for short periods of time in the winter, which means that there is almost no permafrost in Germany. But you can find permafrost in the Arctic and Antarctic and in the high mountain areas of the earth.
Even though permafrost is defined as "continous", the ground is not frozen at all depths throughout the year. Over the summer time the top layer of soil oftens thaws because of the positive air temperatures. This layer is called "active layer". The continous frozen condition is actually good, because as long as the ground is frozen, there is very little reformation. About the same way we expect to be home in the freezer. Once the soil thaws, however, many different processes start to take place. With liquid water, all kinds of fabrics and heat are distributed in the soil. The annual freezing and thawing exerts forces on the ground, for example, the shape of the island endemic polygonal tundra.
A very great importance is the process that fits very well with the example of the freezer; a process where the bacteria begin to process the existing carbon in the soil resulting in carbon dioxide and methane. This makes the permafrost a particularly interesting element in the climate system. If the temperature keeps rising due to global warming also in the permafrost regions, it can accelerate the thawing or the permafrost might even completely disappear in certain places. That would result in significant increase in bacteria which in turn would release more carbon stored in the soil in the form of greenhouse gases. A so-called positive feedback.
The actual permafrost is thus below the depth of maximum thawing of the soil in summer. Here on Samoylov it is at about 40 centimeters below the surface. What it means exactly for our work is that we have over 40 centimeters of slush on top of rock hard frozen ground. At greater depths the temperature rises again steadily due to the heat flow from Earth's interior, so that the soil thaws again at a certain depth. How deep the actual permafrost is depends on current average temperatures, but also on the climatic conditions in the past. Here in northern Siberia the partial depth is about one kilometer, which can be explained by the fact that this area was higher than surrounding areas in the last ice age, and was not protected by layer of ice.
I hope we were able to explain you some important basics about the permafrost. But do not worry, the blog will not become an online textbook and in the next posting we will come back to you with some more current expedition news.
Max
To learn more about the basics of permafrost, please take a look at the PAGE21 Fact Sheet no.1
______________________________
Main page of the English translation of the blog "Tundra Stories" can be found here
Original blog in German: http://www.awi.de/de/go/Tundra-Stories