Written by: Mansi Samre || Graphics by: Mansi Samre|| SEO : Aarushi Mahajan
Permafrost is used to describe any terrain (from soil to rock formations) that remains frozen for 2 or more consecutive years, on the land or the ocean floor. It can extend up to a few feet or can last up to several miles underneath the surface of the earth. A frozen terrain is not the same as permafrost. If a terrain freezes and thaws every year it is considered seasonally frozen. Permafrost is usually found in areas with a cold climate. Most of the present-day permafrost was formed during the ice age. lets discuss how to stop permafrost melting .
Just above the permafrost, is a layer of soil called the active layer, which thaws each summer and refreezes each winter. The thawing and refreezing of the active layer creates interesting patterns on the ground known as ice-wedge polygons. Ice wedge polygons often point towards the presence of permafrost underneath.
Thawing permafrost climate change
How does it form?
Permafrost forms when the water trapped between the rocks, soil, and sediment formations freezes and turns into ice when the temperature drops below 0°C (32°F). It does not always exist in one solid mass. Therefore it is divided into two categories called continuous and discontinuous permafrost.
Continuous permafrost is a continuous mass of frozen ground under the surface of the earth. It occurs when the temperature in a region remains below freezing temperatures (-5°C or below) all year round. Since the temperatures are not high enough to thaw the permafrost persists. It is stretched out under all surfaces except large water bodies in the area.
Discontinuous permafrost is characterized when the mass of frozen ground is broken up into separate areas. It occurs when the temperature in a region keeps varying from season to season. If the annual temperature of the region is anywhere between 0°C to -5°C, permafrost will only form in the places that are screened like areas with thick vegetation or areas in the shadow of a mountain.
Magnitude on earth
Most of the permafrost in the present day is found in the northern hemisphere. About 24 percent of the ground or 19 million square kilometers of the northern hemisphere is covered in permafrost. Most of this belt is in Greenland, Serbia, Alaska, and Northern Canada.
In the southern hemisphere, most of it would lie in the southern ocean if there were land there. It is therefore found in the discontinuous state in the regions such as the South American Andes and New Zealand’s Southern Alps. The continent of Antarctica is covered in glaciers. The terrain under this is largely covered in permafrost.
A brief timeline
Throughout the earth’s history, evidence suggests that permafrost has gone through expansion and corrosion. Its existence dates back to 2.6 million years ago. The recently found remains of the wooly mammoth and other Pleistocene animals in Serbia, Alaska, and Canada, provide us with a confirmation. More evidence comes from studying the frozen layers of the earth’s crust. In some regions, the upper layer of permafrost lies below the modern seasonal freezing. The temperature lowers as we get deeper. This indicates the existence of relict cold. Finally, the presence of permafrost on continental shelves underneath Kara and Beaufort seas tell us that it was formed millions of years ago as it could have only been formed when the sea levels were low.
Thawing and its impacts
By definition, permafrost remains frozen for two or more years. The permafrost on our earth has gone through significant changes over time but human activities have sped up this process. The thawing of permafrost has negative effects on ecosystems, economies, landscapes, and topography.
Damage to the environment
Due to the warming temperatures because of global warming, the active layer penetrates deeper into the ground. If the active layer thaws too deep it is difficult for the permafrost to recover each year. Under the surface of the earth, it acts as a binding component, binding soil, rocks, and other loose sediments. Therefore the melting of permafrost makes the ground unstable and increases the chances of erosion and landslides, particularly in coastal areas. New sediment is introduced into the rivers and streams as a result of soil erosion. This can alter the trails of rivers and streams and also damage the quality of water, affecting the quality of water in the area.
Thawing permafrost can lead to water in the ground sinking deeper which makes us more vulnerable to forest fires. Forest fires can cause more thawing of permafrost and the cycle repeats.
Damage to infrastructure
In towns and cities built in these regions, infrastructure was laid assuming that the solid foundation of permafrost would not change. Thawing can cause the ground to cave in or crack. This can cause a lot of damage to the infrastructure in these areas and can cost millions in repairs. In high altitude areas, thawing can cause landslides which can be a threat to human life. Thawing will also increase the sea levels and cause flooding in major cities further damaging the infrastructure.
One of the most striking examples of permafrost thaw is in Russia called the Batagaika crater. Also known as the gateway to the underworld, it’s over half a mile wide and 300 feet deep and is the largest crater caused by permafrost thaw. As the exposed crater continues to thaw, it expands about 60 feet every year. If this were to happen in any area habituated by humans, it would cause great damage to life and property. Scientists say this is the first of many and should be taken as a warning sign.
Due to climate change, the melting of permafrost is gaining pace faster than ever. When plants and animals die they release methane, carbon dioxide, and other greenhouse gasses. This organic matter has been preserved in the permafrost for thousands of years now. Due to thawing, this organic matter is now exposed to microorganisms which will start the process of decomposition. This will lead to huge amounts of carbon dioxide and methane being released into the environment.
There is more carbon locked in the permafrost than humans have released in the atmosphere since the beginning of the industrial age. There is about 1.8 trillion tons of carbon locked which has already begun to thaw. Once these greenhouse gasses are released into the environment, they are trapped in our environment and increase the temperature of our atmosphere. This in turn results in more rapid thawing of the permafrost. Thus the cycle keeps repeating. This cycle is called the “permafrost feedback carbon cycle”. An increase in the atmospheric temperature will lead to the growth of more trees, which in turn will remove carbon from the atmosphere on a small scale. But it is still not enough to reverse the cycle.
The reemergence of ancient diseases
Along with the various greenhouse gasses, there are also several microbes that have been frozen into the permafrost for thousands of years. As it thaws, along with the gasses, these microbes would also be emitted into the atmosphere. It is believed that some bacteria and viruses can lie dormant for thousands of years. As the temperature gets warm, these bacteria and viruses will become active again, causing an outbreak.
In December 2016, a far off secluded community in Siberia experienced a bizarre outbreak of a disease. Russian officials identified the disease as anthrax. There had not been an anthrax outbreak in the area in nearly 70 years. The outbreak started in raindeers and spread to humans. They burned over 2000 reindeer carcasses. The scientists then began looking underground. The scientists believe that the anthrax outbreak was caused by the carcass of a long-dead reindeer that thawed out along with the permafrost. But it’s not just anthrax. Scientists believe that the thawing will bring back the diseases that we thought we had under control like smallpox and Spanish flu.
The history of permafrost suggests that it is decaying now faster than ever as a result of global warming. As it thaws more, the atmospheric temperature starts rising and the cycle continues. The discontinuous permafrost will be the first to disappear followed by the continuous. Scientists have predicted widespread thawing of permafrost by 2100. This will cause catastrophic effects on our environment and the human population. Therefore the issue of climate change should be of utmost priority to us right now or it could cause irreversible damage to our environment.