eAn international research team discovered the oldest permafrost in Siberia. A 50-meter layer of soil froze for about 650,000 years, like this Alfred Wegener Institute (AWI) announced on Tuesday in Bremerhaven. This means that this permafrost layer has already survived several cold and warm periods.
According to experts at the Helmholtz Center for Polar and Marine Research, this is important because it shows that permafrost does not have to thaw completely, even in the warmest times. The permafrost examined apparently survived the particularly warm phases about 130,000 years ago, when it was about four to five degrees Celsius warmer in the Arctic in summer than it is today.
On the other hand, the discovery near the Batagay community in eastern Siberia also shows how sensitive permafrost is to human disturbances. The 650,000-year-old permafrost is located on a mountain slope at a depth of about 50 meters, where there is a constant temperature of about minus ten degrees Celsius.
However, the slope was partially deforested between the 1940s and 1960s and was transported by heavy-track vehicles from a nearby mine. As a result, the protective and insulating vegetation was lost. As a result, the smaller permafrost at the surface thawed in summer until the ground finally began to slide and expose the old permafrost.
The damage is irreparable because the exposed permafrost continues to thaw each summer. AWI researcher Thomas Opel explained that in the past 50 years, the landslide has expanded to a width of about 900 metres.
Permafrost consists of permanently frozen soil and rock, sometimes several hundred meters deep. They occur mainly in North America and Siberia, but also in high mountains, such as the giant freezer, preserve huge amounts of dead biomass, mainly plant remains, but also animal remains from the last Ice Age such as mammoths and woolly rhinos.
When the permafrost thaws, the bacteria become active, breaking down the old biomass and, through its own metabolism, releasing greenhouse gases carbon dioxide and methane. Because of climate change, experts fear it will exacerbate global warming.
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