The Arctic spill has contaminated a swath of land that covers roughly 135 square miles (350 square kilometers), according to the BBC. It is believed that ground subsidence, or the sinking or settling of the ground, beneath storage tanks holding fuel at the plant is behind this spill. This incident comes during a time when unusually high temperatures are causing the Arctic permafrost to melt mains the damage control process even more difficult.
What is Permafrost?
Permafrost, ground that remains at or below 0’C for two or more years, underlies about a fifth of the land surface of the Earth. It consists of an active layer at the surface that freezes and thaws each year, underlain by perennially frozen ground.
Permafrost is any ground that remains completely frozen—32°F (0°C) or colder—for at least two years straight. These permanently frozen grounds are most common in regions with high mountains and in Earth’s higher latitudes—near the North and South Poles.
Over half of Canada and Russia, most of Alaska, and north-east China are underlain by continental perma- frost, while alpine permafrost is found at high elevations in middle and low latitude.
What is Permafrost Made of?
Permafrost is made of a combination of soil, rocks and sand that are held together by ice. The soil and ice in permafrost stay frozen all year long.
Near the surface, the soils also contain large quantities of organic carbon—a material leftover from dead plants that couldn’t decompose, or rot away, due to the cold. Lower permafrost layers contain soils made mostly of minerals.
A layer of soil on top of permafrost does not stay frozen all year. This layer, called the active layer, thaws during the warm summer months and freezes again in the fall. In colder regions, the ground rarely thaws—even in the summer. There, the active layer is very thin—only 4 to 6 inches (10 to 15 centimeters). In warmer permafrost regions, the active layer can be several meters thick.
What is Thawing?
As Earth’s climate warms, the permafrost is thawing. That means the ice inside the permafrost melts, leaving behind water and soil.
Thawing permafrost can have dramatic impacts on our planet and the things living on it. For example:
- Many northern villages are built on permafrost. When it is frozen, it’s harder than concrete. However, thawing permafrost can destroy houses, roads and other infrastructure.
- When frozen, plant material in the soil—called organic carbon—can’t decompose, or rot away. As permafrost thaws, microbes begin decomposing this material. This process releases greenhouse gases like carbon dioxide and methane to the atmosphere.
As the frozen ground warms much faster than expected, it’s reshaping the landscape—and releasing carbon gases that fuel global warming.
One of the potential danger associated with Permafrost thawing is the breakdown of methane hydrates, also known as “clathrates”. This is methane “ice” that forms at low temperatures and high pressures in continental margin marine sediments or within and beneath permafrost.
Of particular concern are the methane hydrates stored beneath the East Siberian Arctic Shelf (ESAS), a shallow coastal region to the north of Russia. Studies have suggested that thawing is releasing this methane, letting it bubble up and out of the seawater.
- When it thaws, so do ancient bacteria and viruses in the ice and soil. These newly-unfrozen microbes could make humans and animals very sick. Scientists have discovered microbes more than 400,000 years old.