Every year, most often on Earth Day, we hear about how the permafrost is melting or rather thawing and how that is very bad. But in what ways and how bad is this whole process really?
Permafrost is soil that remains at temperatures below or at freezing point (0°C/32°F) for at least two years at once. It is mainly found around the Arctic, covering roughly 25% (23 million km²) of the land area in the Northern Hemisphere alone and reaching depths of more than 1500 meters.
Most of it formed during glacial periods, millions of years ago, and has persisted through warmer, interglacial periods. As such, the permafrost is of huge importance to the whole geological landscape.
Though it remains frozen all year through, during warmer months, when the temperature rises to over 3°C, the surface layer of the permafrost thaws, this way enabling the soil to incorporate plants and animal bodies. Once the temperatures fall back under 0°C, these can be preserved for thousands of years, along with the pathogens they may carry.
Besides the carbon of organic provenance, there are also pockets of carbon; naturally occurring soil carbon, buried under layers and layers of permafrost.
With temperatures rising due to global warming, the whole cryosphere is in great danger.
Right now, the permafrost keeps all that organic matter from decomposing. It also prevents the release of greenhouse gasses such as methane and carbon dioxide into the atmosphere and preserves the bacteria and viruses which, though not active while frozen, are still able to infect whenever released. These are known as zombie-pathogens.
Not only does this alone pose a great threat to the environment and to humans, should the permafrost melt completely, but carbon pockets also create underground low-oxygen environments which, when waterlogged, are likely to contain methane-producing microbes, thus increasing the volume of greenhouse gasses released when that area of permafrost melts.
Thanks to several studies of the chemical structure of sediments drilled from the bottom of the Arctic Ocean, scientists were able to determine that during interglacial periods, when large areas of permafrost thaw, substantial portions of soil collapse into the ocean as a result of massive landslides. The number of such events has reached a spike since 1984, according to data collected in the northernmost areas of Canada.
Studies into the exact amounts of greenhouse gasses released yearly due to thawing permafrost are still in process. One estimate puts the number at 1,700 billion tonnes of organic carbon — double the amount already existent in the atmosphere.
This creates a positive feedback loop where the increase in the quantities of greenhouse gasses in the atmosphere leads to higher sea levels, which in turn leads to more of the cryosphere being affected and more greenhouse gasses (and infectious pathogens) being released.
Overall, it’s just a hellish cycle feeding itself into oblivion. We are making it happen and we are going to pay the price for it all.
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