Permafrost's Impact on the Environment
Written by Kaho Ishihara
What is Permafrost?
Permafrost is any ground that remains frozen for at least two consecutive years. The ground—soil, rock, and/or sediment—is held together by ice. It also contains organic carbon that is accumulated from dead organisms over thousands of years. It is often found in the North and South Poles, Russia, Greenland, China, and more.
Permafrost has a layer of soil on top called the active layer, which thaws in the summer and freezes again in the fall. During warmer seasons, the active layer becomes deeper, melting parts of the permafrost. When frozen, ice in the permafrost fills the gaps between the ground, preventing water from penetrating further into the soil.
How does Global Warming Impact Permafrost?
Rising global temperatures cause the active layer of the permafrost to thaw further, melting a larger portion of the permafrost. This allows water to penetrate deeper into the ground, changing soil moisture and ultimately affecting available vegetation. When water penetrates deeper into the ground, the surface becomes dry. Coupled with hotter, drier summers, this has led to “more large fires in the last ten years than in any decade since recordkeeping began in the 1940s” (U.S. Climate Resilience Toolkit).
As permafrost thaws, greenhouse gases are released, contributing to global warming, which causes more permafrost thawing, creating a cycle. Ancient bacteria and viruses are also released, which can pose a significant threat to humans who lack immunity to these newly released organisms. According to NASA, scientists have discovered bacteria up to 400,000 years old released from thawed permafrost.
New research has found that in the Arctic, more carbon is released than absorbed, due to the greenhouse gases emitted from permafrost thawing. The decreased levels of sea ice have also contributed to shoreline recession. Although previously, the average erosion rate at Arctic coastlines was 0.5 meters per year, the softer ground has caused this number to skyrocket, where one storm could erode up to 20 meters of shoreline (The Arctic Institute).
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