What happens when the soil thaws?

The ice in permafrost acts as a glue that holds it together. The overlying thaw layer is interspersed with partially decayed organic material. Permafrost can be very thin, or it can reach a depth of up to 1500 meters. The thaw layer, also called the active layer, usually thaws every summer. It contains carbon from vast amounts of dead plant material deposited in the soil. When the permafrost thaws, microbes become active and begin to metabolize the carbon, consuming oxygen and producing carbon dioxide.

As climate change progresses, it threatens to thaw deeper permafrost layers, not only downward from the overlying layers but also through erosion on coasts and riverbanks, and through lakes that “thaw their way” into the landscape. The latter process, called thermokarst, is particularly important as it thaws permafrost up to a depth of 30 meters in only a few years, making organic material from the last ice ages available again. Current studies show that permafrost regions are warming much more strongly than others, and their soils are thawing much faster than expected.

The carbon stored in the ground is being released in more and more places. That can result in serious consequences for the global climate, biodiversity and society