Climate Change Is Creating Strange ‘Polygon Fields’ In the Arctic, and Scientists are Worried

Weird polygonal landscapes are emerging in remote reaches of the Canadian High Arctic, a discovery that exposes the extreme changes that polar regions are experiencing as a result of human-driven climate change, reports a new study. 

Scientists reconstructed the evolution of Muskox Valley—a five-mile-long hollow on Axel Heiberg Island in the Arctic Archipelago—across 60 years using aerial photos, satellite data, models, and a field expedition that took place in the summer of 2019. 

The results revealed geological formations called “polygon fields,” named for the shape of their outlines in the ground, that are produced by the freezing and thawing of frozen soil called permafrost. These polygon structures are forming on a scale of decades in the Canadian Arctic, much faster than previously expected. The polygons could hasten the erosion and thawing of Arctic permafrost, potentially releasing vast stores of greenhouse gasses that are trapped in the frigid soil—an outcome that would further exacerbate the climate crisis.

Temperatures are increasing all around the world as a result of climate change, but nowhere is as deleteriously affected as the Arctic. Average temperatures in this region are rising at least three times faster than the rest of Earth, an effect known as Arctic amplification. The Arctic climate has profound impacts on the whole planet; the thawing of permafrost, in particular, could unleash irreversible changes to the global climate. 

Now, researchers led by Shawn Chartrand, an environmental scientist at Simon Fraser University, have discovered rapidly forming polygon fields in the Canadian High Arctic that may increase rates of permafrost thaw. The team notes that “cascading effects” from permafrost thaw “can enhance the release of greenhouse gasses within these environments,” a finding that helps to “raise recognition and awareness of process-based positive feedbacks with climate warming,” according to a study published on Tuesday in Nature Communications.

 “Possible implications of the polygons is that their presence can speed up the rate at which new channel networks develop,” Chartrand told Motherboard in an email. “This means faster rates of erosion. As channel networks grow and deepen, more summer heat can enter the ground and speed up ground ice and permafrost melt.” 

“As a result, we hypothesize that this introduces a new positive feedback, which could enhance the rates of greenhouse gas release to the atmosphere, which depends, in general, on how much carbon is stored in the ground locally, and how quickly bacteria start breaking it down,” he continued. “We have no idea how important (or even if) this process may be at the global scale, but the hypothesis merits further exploration and testing to better situate the idea in the conversation.”

Chartrand, who is an expert on rivers, developed an interest in Muskox Valley years ago after examining satellite imagery of Axel Heiberg Island taken by NASA’s ICESat-2 spacecraft. The images revealed interesting river and ground patterns that could be linked to recent anthropogenic climate change, and its amplification in the Arctic, making it an ideal site to explore the complex dynamics of permafrost in a warming climate.

“We had no idea what we would find when we arrived at the valley, and when we pulled over the ridge leading down into the valley a big smile cracked over all of our faces,” Chartrand said. “We worked off of basic intuition. Something in the ICESat-2 imagery was intriguing, mainly the fact that a small river looked like it's course was rectilinear, and controlled by ground patterning not observable in temperate climates.”

“The 60-year reconstruction came later,” he added. “I searched for historical aerial photographs and the oldest with good views of the valley are from 1959—this set our clock on what we could try to piece together.”

With this approach, the researchers were able to recreate the complex evolution of the Muskox Valley as global temperatures began to rise over the past several decades. This long-term view of the area revealed that polygon fields can form rapidly, and that these features influence watery runoff in the valley, which is in turn linked to erosion.

“One thing that surprised us was the apparent development of polygons over time scales of just decades,” Chartrand said. “This is a relatively rapid time scale compared to expectations from existing theory (more on the order of a century or more time is needed, or an equivalent number of freeze-thaw cycles). This introduces uncertainty in our understanding, and represents a key question to examine in more detail—what are the relative time scales involved in the development of polygons in permafrost landscapes?”

“The question is also more broadly exciting because we see similar features on the surface of Mars (although their geometry is much larger than that on Earth, in general),” he noted. “Another aspect that was surprising is that our attempts to understand the valley profile using metrics that are useful for rivers in temperate climates offered nothing but confusion. This is also exciting because it points to knowledge gaps in our understanding of river systems in cold environments, leaving the door open for more exploration.”

To better understand the polygons, and their implications for the Arctic, Chartrand and his colleagues are working to unravel the mysterious physics that govern sediment particle erosion in frozen, or semi-frozen, environments. By piecing together parts of the permafrost puzzle, the researchers hope to anticipate the changes that this important region will experience in an age of Arctic amplification. 

Indeed, even as Chartrand and his colleagues reconstructed the past and future of Muskox Valley, they could not ignore the obvious transformation of the Arctic in the present. 

“We just happened to be on Axel Heiberg during a quite warm period during the summer of 2019; this relates to the elevated warming in the Arctic that everyone hears of in the news,” such as intensifying heat waves, he said. “On the ground this means we saw hillslopes falling apart in real time because of accelerated ground ice and permafrost melt, rivers were running at flood stage for extended periods due to accelerated ice cap melt (this made getting drinking water a real challenge), etc.” 

“The whole landscape was literally changing right in front of us," he concluded.