Permafrost

Permafrost is most commonly found in polar regions and high mountains, where temperatures stay cold enough to preserve frozen layers year after year.

Although it might sound like a static block of ice, permafrost plays a vital role in the Earth's climate system. It helps store carbon, shapes entire landscapes, and supports human infrastructure in Arctic regions. As the planet warms, this frozen ground is beginning to thaw—triggering wide-ranging effects that stretch far beyond the Arctic.

More than just frozen soil

Permafrost can consist of many different materials, depending on location and local geology. In most cases, it is a frozen mix of:

• Mineral soil such as sand, silt, or clay
• Rock and gravel, often held together by ice
• Organic material, including ancient roots, leaves, and peat
• Ice, which fills the pores and spaces between soil particles or forms solid layers

In some regions, ice can make up more than half the volume of permafrost. These high-ice-content zones are especially vulnerable to thaw, since melting ice leads to ground collapse and surface deformation.

Above the permafrost lies the active layer, which freezes and thaws with the seasons. The depth of this layer can vary widely—from about 20 centimeters in colder zones to over 3 meters in warmer permafrost areas. This layer supports tundra vegetation and provides the only surface where roots, animals, and microbes are active during the summer months.

Arctic regions and high-altitude zones

Permafrost is not spread evenly across the globe. It is mostly concentrated in the Northern Hemisphere, where it covers roughly twenty to twenty-five percent of land areas. Key locations include:

• Siberia and the Russian Arctic, home to some of the deepest and oldest permafrost layers
• Northern Canada and Alaska, where communities and infrastructure depend on stable frozen ground
• Greenland, especially along the coastlines and ice-free interior valleys
• Mountain regions, including the Tibetan Plateau, the Alps, the Andes, and parts of the Rocky Mountains
• Underwater areas, particularly along Arctic coastlines, where permafrost can extend beneath the seafloor and remain frozen under sediments

Permafrost zones are categorized as continuous, discontinuous, or sporadic—depending on how consistently frozen the ground is in a given region. In continuous zones, permafrost exists almost everywhere beneath the surface. In discontinuous zones, patches of frozen and unfrozen ground alternate.

How rising temperatures affect permafrost

As global average temperatures rise, permafrost is beginning to thaw more deeply and more quickly than in the past. Even small increases in temperature can have major effects, especially in regions with high ground ice content.

Thawing permafrost destabilizes landscapes, changes water drainage patterns, and transforms ecosystems. Forests growing on permafrost can begin to lean or fall as the ground becomes soft and uneven—a phenomenon known as drunken forests. In lowland tundra, the thaw can create wetlands or thermokarst lakes as ground ice melts and the land sinks.

Worse, thawing releases carbon dioxide and methane, potent greenhouse gases trapped for millennia in frozen organic matter. Microbes begin to break down this material as soon as it thaws, turning permafrost into a new source of emissions. Scientists estimate that permafrost contains nearly twice the amount of carbon currently in the atmosphere, meaning its thaw could significantly accelerate global warming.

Risks associated with permafrost thaw

The thawing of permafrost brings a wide range of risks—not just for Arctic communities, but for the planet as a whole. Some of the most serious risks include:

Climate feedbacks

Thawing permafrost contributes to a climate feedback loop, where warming causes emissions, which cause more warming. This feedback is already visible in northern regions where permafrost is degrading faster than predicted.

Infrastructure instability

Many buildings, roads, airports, pipelines, and other infrastructure in cold regions were constructed on the assumption that the ground would remain permanently frozen. As permafrost softens and subsides, this infrastructure becomes unstable, leading to costly repairs and engineering challenges.

Coastal erosion

In Arctic coastal areas, permafrost thaw combines with rising sea levels and increased wave action to cause rapid shoreline retreat. In some communities, erosion is forcing relocation and displacing long-standing settlements.

Public health concerns

Thawing ground can expose ancient biological material, including viruses, bacteria, and pathogens that have been dormant in frozen layers. It can also disturb long-buried industrial waste, abandoned military sites, or improperly stored chemicals and fuel tanks.

Why permafrost matters for everyone

Permafrost may seem like a frozen relic of the far north, but its stability affects the entire planet. As the ground thaws, it releases carbon, changes landscapes, threatens infrastructure, and transforms local ecosystems—all with global consequences.

Scientists around the world are studying permafrost closely to understand its role in the climate system and to prepare for the changes that are already underway. Whether you live near the Arctic or far from it, the thawing of Earth’s frozen ground is one of the clearest signals of a warming planet—and one of the most urgent to watch.