A Homer scientist is bringing changes in Arctic permafrost into high-resolution
With permafrost thaw in the Arctic rapidly outpacing previous projections, researchers are racing to understand the impacts of an increasingly unstable future.
After growing up in Sweden, Anna Liljedahl moved to Alaska to study hydrology at the University of Alaska Fairbanks. She now lives in Homer, where she conducts research as an associate scientist at the Woodwell Climate Research Center, focusing on how climate change is impacting water in Arctic ecosystems.
Liljedahl is now leading a team to create more accurate, interactive maps of Alaska’s permafrost. Their project, called the Permafrost Discovery Gateway, is a novel effort to make Arctic research quicker to share and easier to access. That’s critical as the climate crisis accelerates thaw, impacting Alaskan communities and global carbon and methane emissions.
“Changes are happening so fast that we need to come up with automated ways of tracking this permafrost thaw through remote sensing imagery,” Liljedahl said, “and make automated tools that help us identify where change is happening.”
Permafrost is ground that remains frozen for at least two consecutive years, though some of it has been frozen for thousands of years. Scientists estimate that more than 80% of Alaska has permafrost. In some places, like the North Slope, it stretches continuously across the entire region, where it can be 2,000 feet thick. South of the Brooks Range, though, the permafrost layer is often much thinner, and broken up by patches of unfrozen ground.
The actual ice content of permafrost also varies. Liljedahl said regions with high ice content, called ice-rich permafrost, are exciting from a scientific perspective, but also create the biggest challenges for houses, buildings and roads.
“So imagine, if you melt that ice, it's going to become water,” she said. “Then suddenly the soil doesn't have any support anymore.”
Though damage to infrastructure may not be as immediate as other natural disasters, rapid thaw is already having a huge impact on Alaskans. Some people, for instance, have had to level their home foundations multiple times a year.
“There's insurance for flooding and hurricanes that people can buy and utilize, but when it comes to permafrost thaw, there's nothing,” Liljedahl said. “People are just left on their own.”
Getting a better sense of how much ice is in Alaska’s permafrost is also important for modeling potential greenhouse gas emissions as it disappears.
“You need to know how much carbon is in the permafrost to begin with, and that estimate depends on how much ice you have,” she said. Permafrost with less ice in it has more organic material, like frozen roots, which release more greenhouse gasses like methane when it thaws.
With temperatures rising across the far north, the climate crisis is rapidly changing the ground. Liljedahl said it can take a decade for research in the Arctic to get peer-reviewed and published, and with changes now outpacing many projections, that’s just not fast enough.
“Ten years is a long time frame in Arctic permafrost thaw,” she said.
The Permafrost Discovery Gateway provides a new level of detail and scale to mapping the Arctic, and could help fill these gaps with more automated tools, helping scientists better track how these ecosystems are shifting.
“We had to create our own software, our own visualization tool, where you can view this really, really big map at the pan-Arctic scale, and at the same time, zoom in and look at what's happening in your backyard,” Liljedahl said.
One of the features this high-resolution imagery can help researchers identify are called ice-wedge polygons. Over years of freeze and thaw cycles, water flows into cracks in the ground and gradually builds into walls of ice below the surface. These ice wedges push soil into distinctive shapes — visible to satellites — and stand out as they thaw, causing the ground above to slump or new ponds to form.
Being able to see these kinds of changes is shedding new light on Arctic trends. Elizabeth Webb is a postdoctoral researcher at the University of Florida who has shared research on the Permafrost Discovery Gateway database. She has been studying the connection between vanishing surface water and permafrost thaw.
Previous models projected thawing would initially increase water in lakes, and then decrease later this century with more sustained warming. But that’s not how things seem to be playing out.
“What my research was showing is that it's just the very beginning of the 21st century,” Webb said, “and we have already reached the latter part of that continuum.”
Instead, in some regions, surface water is disappearing more quickly than anticipated, according to research Webb and Liljedahl published earlier this year. Warmer temperatures lead to increased autumn rainfall in the Arctic, so having less surface water is a little counterintuitive, Webb said.
“You would think more rain would mean more water. But actually, more rain means more permafrost thaw — which means more drainage.”
This can be a big issue for Arctic communities. Not only can permafrost thaw damage homes and infrastructure like pipes, it can also impact the availability of reliable drinking water as lakes shrink or drain completely.
“People rely on lakes for household use and for drinking water. It's not like all the lakes are going to drain and then suddenly, there's not going to be any water left for them,” Webb said. “But it does mean that these communities are now more vulnerable.”
Researchers across the state are working hard to better understand these intricacies — and the unique Alaskan landscapes permafrost has created. On a recent virtual tour of the U.S. Army Corps of Engineers’ permafrost tunnel in Fairbanks’ Goldstream Valley, senior scientist Tom Douglas welcomed more than 500 viewers across the country on a journey back through time.
With geologic formations stretching millennia, Douglas said that there is no other tunnel quite like this one.
“You can wander through, and on the walls you can map different features. You can measure them, you can do statistics on them, [and] we can collect samples representing about 40,000 years of permafrost formation,” he said.
Getting field data from different areas around the state is still a huge challenge, making samples from the permafrost tunnel incredibly valuable. The tunnel offers a glimpse of geologic shifts in permafrost, and an up-close look at changes that satellites can’t see from above.
Douglas said permafrost researchers need to get better at talking to the public about their work, sharing data and making information more accessible. That includes everything from looking at historical mining pictures, to getting people across Alaska to share their lived experiences and observations.
“We really need any type of information possible and ways to basically accumulate, synthesize and display that information,” Douglas said.
Permafrost may be a northern phenomenon, but the consequences of carbon emissions released around the world have a huge impact on how quickly these changes are happening in Alaska. Permafrost holds twice the amount of carbon than is currently in the atmosphere, Douglas said. Accelerating thawing also has the potential to magnify the impacts of climate change globally — releasing more carbon and methane and speeding temperature rises.
Liljedahl said using tools like satellite imagery, mapping, and up-to-date visuals can help create a better picture of this rapidly changing area of the world.
“We're not just talking about 50 years from now. We're talking about what happened yesterday, and what's happening right now.”
You can take a digital stroll back through thousands of years of geology on a virtual tour of the permafrost tunnel outside of Fairbanks, and explore the growing database of permafrost research on the “Permafrost Discovery Gateway.”