What happens when permafrost thaws?
Just like a gigantic freezer, permafrost stores tremendous amounts of organic matter. Unlike in tropical or moderate climate zones, this organic material can’t be broken down by microbes, since these bacteria only become active when the permafrost thaws. But if our climate continues to grow warmer, the door of that gigantic freezer is left open and the organic matter starts to decompose - carbon will be broken down and be released into the atmosphere as greenhouse gas, which will in turn accelerate the climate-warming process. The permafrost carbon feedback would affect the global climate system as a whole. Further, melting of ground ice present in permafrost can have drastic consequences for arctic landscapes and settled areas, because the land surface settles unevenly where ice turns to water and streets, railroad tracks, runways, buildings, and oil and gas pipelines become damaged.
Unfortunately, predicting the physical and biochemical development of permafrost is an extremely complex undertaking. Many surface characteristics change simultaneously, like snow cover and vegetation, which produces varied and often opposing effects. Further, human beings are increasingly interfering in landscape development. As such, predictions still involve a great deal of uncertainty. However, studies of past climate change such as during the period immediately after the last ice age when the Arctic warmed very rapidly have shown that permafrost was dramatically affected by warming, suggesting that permafrost may not be so permanent at last.