The permafrost is a frozen land or soil beneath the Earth's surface or topsoil that has been completely frozen for at least two straight years.

On the land, permafrost usually lies beneath the ‘’active layer” of soil which freezes and thaws annually.

The frozen ground can consist of many materials such as bedrock, sediment, organic matter, water or ice. The ice binds all the components in the permafrost together.

During the thawing process, ice content of the soil melts and this melting water starts draining through soil weakening the soil structure by turning it to mud slurry which can not support the soil and vegetation above it and also increases erosion as soil and sediment are easily washed away without ice.

Layer on the permafrost is called the “active layer” as it does not remain frozen all round the year. It freezes in winters and melts in summers.

Only plants with small roots or have limited rooting zones can survive in presence of permafrost for example, black spruce with its small and wide spreading roots is the dominating flora species of the extensive permafrost.

A third of 99% of the world's permafrost could melt if emissions of greenhouse gases continue unabated as per UN draft reports.

Impacts of Permafrost Thawing

The permafrost thawing will have a profound influence on global climate in future. The effects of permafrost thawing will not only be concentrated in the area where it is located but extends globally by impacting Earth’s climate system.

The large amounts of dead biomass that have accumulated through millennia is contained within the permafrost. That makes the tundra soil a carbon sink. If temperature rise continues unabated, emission of this carbon from thawing will have a sufficient impact on the climate.

Due to the effects of climate change, the risk of wildfires also increases in the Arctic which can speed up carbon emissions from permafrost.

The plant materials trapped within the permafrost won't decompose or decay until permafrost starts thawing. As temperature rises, permafrost thaws, which increases the biological activities within it (ground) such as decomposition of organic matter (like remains of plants) by microbes which results in the release of carbon back into the atmosphere.

Recently Big Trail Lake, a newly emerged lake due to permafrost thawing in Alaska is releasing methane gas into the atmosphere because microbial activities have started as permafrost is thawing.

Emission of carbon from the permafrost in forms of carbon dioxide and methane into the atmosphere further contributing to global heating which in turn causes permafrost to thaw.

The amount of carbon that has already been released into the atmosphere due to modern human activities is only one fourth (1/4th) of the carbon currently stored in the permafrost, according to some study.

The permafrost holds large biomass, thawing of permafrost will also result in releasing the long-dormant bacteria and viruses that were trapped in the permafrost and can potentially lead to disease spread. In 2016, an anthrax outbreak in Siberia caused 200,000 deaths of reindeer as the result of permafrost thawing.

Permafrost thawing can severely impact humans and the environment. For instance, If the permafrost packed with ice thaws, it can turn into a mud slurry that is too thin to support flora and soil above it.

In addition to its impact on climate, permafrost thaw also produces other risks such as Infrastructures such as roads and buildings are damaged and slope failure events in high mountain ranges as the ground above the permafrost destabilises during thawing.

Since the temperature of permafrost depends on the soil types, vegetation above the ground and snow cover depth, hence it can vary across the region. The changes in land use such as agriculture practices, urban development also influences permafrost temperature. Ex, permafrost in northern Alaska is more cooler and continuous than the interior permafrost.

Permafrost temperature is rising at a much faster rate than the air temperature in the Arctic. It has risen between 1.5 to 2.5°C in the last 30 years. In previous times, the Arctic region was considered a carbon sink but now it is emitting more carbon than what it is absorbing, largely because of permafrost thawing as permafrost emits carbon when it thaws.

It has been estimated by the researchers that fires in the Arctic region along with the permafrost thawing could lead to an increase of carbon emissions of up to 40% by the end of this century if the current pace of fossil fuels burning is not drastically reduced as the burning of fossil fuels is the main source of carbon emission.

Carbon contained within permafrost across the world, is almost double the amount of carbon in the Earth’s atmosphere and is four times what humans have emitted since the Industrial revolution. If all permafrost thaw, disastrous effects would be felt across the world.

The Global Carbon Budget has not fully incorporated the permafrost as a source of emissions, despite knowing the potential consequences of permafrost thawing (The Arctic Institute).

Where Is the Permafrost found In the World?

The permafrost is found on land or below the ocean floor or even on mountain ranges. It is typically found in cold climates where annual air temperature remains below the freezing point of water. In the Northern Hemisphere, it is found in the Arctic regions such as Alaska, Greenland, Siberia, Canada and in the Tibetan Plateau, which is a high mountain region.

Majority of permafrost is found in the Northern hemisphere, covering a large land area over 25%.

In the southern hemisphere, it is found in the mountain slopes of the Andes, the Southern Alps or in high mountains of Antarctica.

There are some exceptions as it is also found in the humid boreal forests, such as in Northern Scandinavia. The permafrost is generally distributed in continuous and discontinuous forms. In Siberia, it is found in continuous form and Canada has discontinuous permafrost.

Deep sinkholes have formed in some areas of the ocean floor due to thawing of submarine permafrost. And in other areas, pingos ( ice-filled hills) have risen from the seafloor.

The permafrost carbon cycle (Arctic Carbon Cycle)

Carbon from permafrost soils is transferred to terrestrial vegetation and microbes, to the atmosphere when permafrost thaws, and again back to vegetation (through photosynthesis), and finally, back to permafrost soils through burial and sedimentation, is called as permafrost carbon cycle.