The Danger of Melting Permafrost
The areas where the grounds has always frozen since centuries past, comprises 24% of Northern Hemisphere land and is also found in the Southern Hemisphere to a lesser extent. In a normal world without the climate change, only the upper layer of the permafrost, the so called active layer is thawing in the summer. Recent studies12 shows that the thaws will release several billions of tonnes of carbon to the atmosphere. To the extent that if the Carbon is released as CH4 (Methane, a greenhouse gas) they would contribute significantly to the climate forcing, further accelerating warming and causing feedback loops as more and more of the remaining permafrost begins to decompose. Not to mention, it will absolutely change the face of the earth, with the most grim model predicted the loss of 4.8 square kilometers of land.
How did Permafrost Contain That Much Carbon?
Carbon was buried in the permafrost by processes that took millenias. For instance, during the last ice age, great sheets of ice covered much of the continents on earth, as they spread out and then shrunk back, the heavy fields of ice ground up the rock underneath theme into a very fine dust. This dust in turn deposited to the soil by winds and rain3. As the ice sheets added loess to the soil, the soil got thicker, and as it builds up, the active layer on top stayed the same thickness. This active layer freezes and thaws each year, and plants can grow in it. But underneath it, roots and other organic matter were frozen into the permafrost where they cannot decay. This in turn added carbon to the already carbon-rich permafrost. Over the years, Earth’s permafrost contains almost twice the amount of carbon in the atmosphere.
As we briefly mentioned at the top, there are several ways the thaw will impact the planet. There are also others we have not mentioned yet, for instance:
- Grounds became unstable as can be seen recently in Alaska.
- There are some potentials for the previously frozen bacterials, and viruses to spread when permafrost thaws.
- Walvoord, Michelle A. , Striegl, Robert G, Increased GroundWater to Stream Discharge From Permafrost Thawing in the Yukon River Basin: Potential Impacts on Lateral Export of Carbon and Nitrogen. Published in June 2007 by Geophysical Research Letter. [return]
- Edward A.G. Schuur, Jason G. Vogel, Kathryn G. Crummer, Hanna Lee, James O. Sickman, T.E. Osterkamp, The Effect of Permafrost Thaw on Old Carbon Release and Net Carbon Exchange From Tundra. Published in 2009 by Macmillan Publisher Ltd. [return]
- https://nsidc.org/cryosphere/frozenground/methane.html [return]