Unveiling the Arctic’s Dynamic Transformation: Permafrost Thaw Amplified by Climate Change

Across the Arctic, a remarkable transformation is taking place in the landscape. Vast lakes, spanning several square miles, are vanishing within a matter of days. Hillsides are slumping, and the ground is collapsing, creating uneven terrains and sunken polygons. These changes are clear indications that permafrost, the frozen soil beneath the surface, is thawing. This is concerning not only for the communities living above permafrost but also for the global climate.

As an ecologist who specializes in studying these interactions within landscapes, I have been documenting the accelerated changes caused by permafrost thawing over time. The hidden transformations occurring in the Arctic serve as a warning for the future.

So what exactly is permafrost? It refers to perpetually frozen soil that covers approximately 25% of the Northern Hemisphere’s land, particularly in Canada, Russia, and Alaska. A significant portion of permafrost contains the organic matter of ancient plants and animals that have been frozen in time.

This frozen soil provides structural stability to the northern landscapes, similar to load-bearing support beams in buildings. However, as temperatures rise and precipitation patterns shift, permafrost and other forms of ground ice become vulnerable to thawing and collapsing. The destabilization of the ground due to warming then disrupts the intricate fabric that has shaped these dynamic ecosystems over thousands of years. The increasing prevalence of wildfires in the Arctic further escalates the risk.

Beneath the surface, another process is at play, exacerbating global warming. When the soil thaws, microbes start to decompose the organic matter that has been frozen for countless millennia. As these microbes feed on the organic material, they produce carbon dioxide and methane, two potent greenhouse gases. When released into the atmosphere, these gases contribute to further climate warming, creating a feedback loop. The warmer temperatures result in more soil thawing, leading to the release of more organic material for the microbes to decompose and produce additional greenhouse gases.

One of the most stunning pieces of evidence demonstrating human-induced climate change in the permafrost regions is the disappearance of large lakes covering several square miles. These lakes are draining either through wider and deeper drainage channels or gradually through unfrozen soil. The surface water across permafrost regions has noticeably dwindled, as confirmed by satellite observations and analysis. Colleagues and I have found a correlation between lake drainage and permafrost degradation, with an increase in warmer and longer summer seasons.

In northwestern Alaska, we have observed some of the highest rates of catastrophic lake drainage, which happens within a few days due to permafrost degradation, over the past five years. The vanishing lakes will likely impact the livelihoods of indigenous communities as it affects water quality, availability, and their necessity for waterfowl, fish, and other wildlife.

Additionally, the thawing of buried glacial ice is causing hillsides to slump across the Russian and North American Arctic, resulting in the downward movement of soil, plants, and debris. A recent study in northern Siberia revealed that disturbed land surfaces have increased by over 300% in the past two decades. Similar studies in Canada have also shown an accelerated rate of slumping with warmer and wetter summers.

In areas with flat terrain, ice wedges can form, giving rise to unique geometric patterns and changes across the land. Over time, melting snow seeps into cracks in the soil, forming ice wedges that create troughs on the ground’s surface, resulting in the formation of polygons. These polygonal features occur naturally due to the freezing and thawing process, resembling patterns seen in drying mud flats. As the ice wedges melt, the ground above them collapses.

Even in extremely cold high Arctic environments, a few unusually warm summers can drastically reshape the landscape, transforming previously flat terrain into undulating areas as the surface sinks into depressions caused by melting ice in the soil. The thawing of ice wedges has accelerated in response to climate warming.

Wildfires have also contributed to increased thawing in many Arctic regions. In a recent study, my colleagues and I discovered that wildfires in permafrost regions lead to a faster rate of thawing and vertical collapse of frozen terrain, which persists for up to eight decades after the fire. Given the projected increase in both climate warming and wildfire occurrences, the rate of landscape change in northern regions is expected to escalate.

The effects of recent climate and environmental changes have even spread to lower latitudes in the lowland boreal forest. Ice-rich permafrost plateaus – elevated islands of permafrost above adjacent wetlands – have rapidly degraded across Alaska, Canada, and Scandinavia. These plateaus can resemble cargo ships sinking into wetlands, carrying sedges, shrubs, and trees.

The significance of these transformations lies in the fact that frigid temperatures and short growing seasons have historically restricted the decomposition of dead plants and organic matter in northern ecosystems. As a result, nearly 50% of the world’s soil organic carbon is stored in these frozen soils.

The abrupt transitions witnessed today, such as lakes turning into drained basins and shrub tundra transforming into ponds, will hasten the decomposition of buried permafrost carbon and above-ground vegetation, as they collapse into water-saturated environments.

Permafrost is most extensive in Russia, which holds the largest permafrost area in the world. However, scientific studies in Russia faced interruptions when Western institutions suspended funding following the country’s invasion of Ukraine in early 2022.

It is estimated that permafrost currently holds twice as much carbon as the atmosphere. The depth of permafrost varies widely, with some parts of Siberia reaching depths exceeding 3,000 feet. Northern Alaska has permafrost depths of around 2,000 feet, whereas Fairbanks, Alaska, averages about 300 feet. Shallow permafrost, which is less than 10 feet deep, is likely to thaw if the world continues along its current warming trajectory.

In oxygen-deprived, water-logged environments, microbes produce methane, a greenhouse gas that has 30 times more warming potential than carbon dioxide. However, methane does not persist in the atmosphere for as long.

The degree to which thawing permafrost will become a significant climate problem remains uncertain. Currently, we know that it is releasing greenhouse gases, but the causes and consequences of permafrost thaw and associated landscape changes are active areas of research.

One thing is clear: the thawing of formerly frozen landscapes will continue to alter high-latitude ecosystems for years to come. For people residing in these regions, the slumping land and unstable soil pose risks and liabilities, including damage to infrastructure like roads and buildings.

This article was originally published in The Conversation and written by Mark J. Lara from the University of Illinois at Urbana-Champaign.