Katey Walter Anthony, an ecologist at the University of Alaska-Fairbanks, dips her paddle into the water as her kayak glides across the lake. “Years ago, the ground was about three meters taller and it was a spruce forest,” she says.
Big Trail Lake is a thermokarst lake, which means it formed due to permafrost thaw. Permafrost is ground that stays frozen year round; the permafrost in interior Alaska also has massive wedges of actual ice locked within the frozen ground. When that ice melts, the ground surface collapses and forms a sinkhole that can fill with water. Thus, a thermokarst lake is born.
Walter Anthony is a researcher collaborating with NASA’s Arctic Boreal Vulnerability Experiment (ABoVE) project. She’s studying the formation of these thermokarst lakes and how this process is caused by and contributes to Earth’s changing climate.
“Lakes like Big Trail are new, they’re young, and they are important because these lakes are what’s going to happen in the future,” she explained.
They’re also belching methane – a potent greenhouse gas – into the atmosphere.
At first glance, Big Trail looks like any lake. But look closer and there’s something disturbing the surface: bubbles.
Two things happen as the permafrost layer thaws beneath lakes: microbial activity increases and pathways form in the permafrost . At Big Trail Lake and other thermokarst lakes in the Arctic, microbes digest dead plants and other organic matter in the previously frozen soil in a process that produces carbon dioxide and methane. More rarely, permafrost thaw can form ‘chimneys’ under lakes that allow methane and other gases – previously trapped deep underground – to escape. This release of ‘geologic’ methane is happening at Esieh Lake, another of Katey Walter Anthony’s ABoVE study sites. In all thermokarst lakes, the gases bubble up to the lake surface and release into the atmosphere.
“At Big Trail Lake, it’s like opening your freezer door for the first time and giving all the food in your freezer to microbes to decompose. As they decompose it, they are belching out methane gas,” says Walter Anthony. She leans over and pushes her paddle into the spongy ground under the water, causing clusters of methane bubbles to erupt on the surface.
As the lake freezes in the winter, the bubbles can prevent ice from forming and create pockets of open water that continue emitting methane throughout the season. In other areas, the methane bubbles create frozen domes of ice on the surface of the lake.
“Once ice has formed on these lakes, the rising methane bubbles will freeze into the ice,” explains Franz Meyer, Chief Scientist at the Alaska Satellite Facility in Fairbanks. Meyer is also one of the chief scientists for NISAR, a joint NASA and ISRO satellite that will study our planet. One of the instruments that will be on NISAR is a radar similar to the instrument the ABoVE team is flying over Arctic and boreal regions to study the ground, ice and lakes below.
“These bubbles that we see in the ice change the way that the radar signal interacts with the ice surface,” he explains. The radar can detect roughness – like from frozen methane bubbles – on the surface of the land, ice and water below. Thermokarst lakes with a high roughness, or more bubbles, tend to have higher methane emissions compared to smooth lakes. Combining the airborne radar data with measurements collected in the field allows scientists to estimate how much methane lakes are emitting across a large region.
Walter Anthony says she has something to show us and paddles over to what looks like a piece of trash: an upside down plastic bottle sticking out of the water. It’s a methane collection device, she says, explaining that the bottle traps methane as it bubbles up through the water. Walter Anthony turns a valve and collects a sample of the gas in a smaller bottle, which her team will chemically analyze to determine the age and concentrations of the various gases within.
But there’s a faster way to know if the lake is releasing methane.
Walter Anthony opens the valve, lights a match, and holds it to the opening. A burst of flame ignites. She lets the flame burn for a few seconds and then turns off the valve. It’s like a more extreme version of lighting a gas stove.
There are millions of lakes in the Arctic, but only the newer ones are releasing high amounts of methane. That’s because most Arctic lakes are hundreds or thousands of years old. Those lakes used to be just like Big Trail Lake, but the microbes there have since run out of permafrost organic matter to decompose, and instead are emitting methane from more modern carbon sources. That means the older lakes are no longer emitting as much old methane.
“So what’s a concern for the future, when we think about permafrost carbon feedback, are areas that are newly thawed,” says Walter Anthony. Just like Big Trail Lake.
Far up in northern Alaska, Logan Berner’s legs are burning with pain from trekking over tussocks in grassy valley bottoms and rugged, cloud-choked mountain passes. He’s spending a couple of weeks of 2021’s summer traversing the mountainous Brook Range, carrying just the essentials to sustain him in the expanse of the Alaskan Arctic. There, where North America ends, tundra and mountains make up one of the continent’s most pristine landscapes.
The Brooks Range is not the sort of environment where people just go for a hike. It’s too remote, too wild, and too cold. There are no human trails other than what’s left behind by moose, bears and other wild animals roaming the region. It’s the kind of terrain that will get you in trouble, the kind that would put you face to face with a hungry grizzly bear or give you hypothermia.
Rain gear is non-negotiable. 2021 marked one of the wettest summers on record in the range, and some days in the trek feel like an endless walk through a car wash. Stopping for more than a few minutes (even to eat) will make your body too cold from the whipping wind and pouring rain near freezing temperatures.
Berner, a research ecologist from Northern Arizona University, went out there to join a group of biologists led by Roman Dial, a professor of biology and mathematics at Alaska Pacific University who had been traversing the range on foot for nearly a month. Covering nearly 800 miles in about three months, the team used their smartphones to take pictures and jot down extensive notes about the vegetation they passed, noting when and how the type and density of trees, shrubs and other plants changed along their way.
By combining those notes with techniques that analyze greenness from space, the team wants to gain a better understanding on the extent and nature of the impacts of climate change right at the boundary between Arctic tundra and boreal forest. The idea is to use that data, recorded the old-fashioned way with boots on the ground, and link them with NASA’s long-term satellite observations.
The Arctic is warming nearly twice as fast as other regions on Earth, and the impacts extend beyond glaciers melting, sea ice shrinking and other types of vanishing polar ice. They reach most deeply into places such as the Brooks Range, where Arctic tundra—a harsh, treeless ecosystem where mostly small plants grow—has become increasingly greener.
Over the last four decades, satellites have detected that greening, as well as some browning, where extreme weather, insect pests, and other disturbances reverse the greening trend. But even though satellite records suggest Arctic tundra ecosystems are changing in response to atmospheric warming, important details remain unclear about why specific regions have greened or browned in recent decades.
“Arctic greening is really a bellwether of global climatic change,” Berner said. “We know that this greening signal in part reflects warmer summers, increasing the amount of plant growth that’s occurring on the landscapes, so that the satellites are seeing this increase in leaf area.”
Already, the effects of these vegetation changes point towards other impacts as the Arctic tundra becomes more productive and shrubbier.
For example, Berner explained, thriving shrubs could out compete smaller plants that serve as important subsistence resources, like blueberries, which help sustain northern human communities. Dial also has observed that these vegetation changes can re-shape the landscape and affect how caribou and other migratory animals navigate the Brooks Range, also affecting the availability of subsistence resources for isolated villages depending on wildlife.
On the flip side, new spruce tree forests can also help insulate the thawing permafrost and possibly reduce the release of deep pools of carbon stored within it, adding more heat-trapping gases into the atmosphere.
“In that sense, [greening] might slow the rate of climate change by keeping that organic-rich permafrost carbon soils frozen and locked away,” Berner said.
Because of the unknowns revolving around Arctic greening and browning, field data serves as a crucial complement to satellite observations. Gradients of vegetation stripe the Brooks Range, making it an ideal location to sample from, as the mountains form a natural barrier that separates the boreal forest of Alaska’s interior from the Arctic tundra of Alaska’s North Slope.
NASA’s satellites can track large-scale vegetation changes from space. But 700 miles up in space, they mostly get a top-down view of the terrain. By venturing into the wilderness to collect the extensive ecological field data that is impossible to capture from space, Berner and Dial’s team are helping the satellites “see” more and better.
The team is combining their detailed notes from the ground with satellite observations of the region by the Landsat program. Ultimately, linking both datasets can help scientists learn more details about where, why, and how large patches of the Arctic’s flora are changing.
“Being on the ground and walking through these landscapes gives you a much better sense for what these landscapes are,” Berner said. “It gives you an understanding of these ecosystems that you just can’t get by sitting at a computer and crunching data.”
The team was able to trek and take data largely thanks to Dial, who has travelled over 5,000 miles throughout the Brooks Range during the last four decades. As part of that exploration, Dial developed ingenious ways to travel light for extended periods of times, making it more manageable to collect data from the field.
“When doing fieldwork in remote Arctic, Antarctic and alpine environments, survival comes first, so you can sometimes feel lucky to perform any research along the way at all,” Dial said. “But our methods of travel have evolved to the point where we can travel light and comfortably—dealing with rivers and bears and rain and wind. By integrating that light and comfortable mode of travel with smartphones and simple tools like tape measures and tree increment borers, as well as other apps on our phones that can measure heights, we can actually collect valuable and useful data across vast swaths of wilderness.”
What really makes recording data on the field possible is what Dial named “pixel walking,” a unique way in which a group of trekking scientists document observations about the vegetation as they see it on the ground, logging changes in plant types, attributes, and location continuously. Their protocols to record that information cover 30-square-meter plots of land, or a pixel of a view from a Landsat satellite.
Most previous field research has involved establishing field plots and meticulously characterizing the plant community in each one. That does provide valuable information, but the approach is expensive, limited in extent and time-consuming. Because field plots tend to be small and few, it can be difficult and prohibitively expensive to cover large areas accurately, and to match them with observations from space.
With a smartphone app developed by Dial’s team, the trekkers note the tallest plant community and its physical structure as might be seen from an orbiting satellite. They also record what isn’t so easy to see from space: the understory and ground cover. As they walk, they record on their smartphones’ app the identity and density of each of three layers of vegetation. The app also records the geographic location with the phone’s GPS.
“It’d be very expensive to collect this kind of data with a helicopter,” Dial said. “This is a really important aspect of ground truthing and calibrating what the satellites see with what’s on the ground. From satellites we only know that the reflectance values are changing over time, but we don’t know what it is that’s changing on the ground. So this is a way to find out what is really happening with plant communities and the Earth’s surface and relate it to the last 20 years of satellite data.”
Berner, supported by NASA’s Arctic Boreal Vulnerability Experiment (ABoVE for short) and Dial’s team, supported by NASA’s Alaska Space Grant, the National Science Foundation’s Established Program to Stimulate Competitive Research, and the Explorers Club/Discovery, are already working to link their field observations with satellite data. What they’ll learn can also help inform future research in other parts of the Arctic.
“What is the greening that we see? Is the greening an increase in willows, for example? Is it an increase in birch? Or is it an increase in alders? Or is it an increase in trees?” Dial said. “Having a small team like mine actually on the ground to provide the ABoVE program with ground-based data—that’s really what ABoVE is doing well. It’s just a really wonderful marriage between field data collection and remote sensing.“
Trudging through snow up to their thighs, researchers Nicholas Hasson and Phil Hanke pull 200 pounds of equipment through boreal terrain near Fairbanks, Alaska. Once they reach their destination – a frozen, collapsing lake — they drill through two feet of ice to access frigid water containing copious amounts of methane.
Hasson lies flat on his stomach and reaches both of his arms into the subzero water. The stench of 40,000-year-old rotting vegetation floats up from the permafrost. He attempts to open the valve on a piece of equipment underneath the water’s surface using his fingers, but his thick protective gloves (water would instantly freeze onto his arms, otherwise) make simple tasks challenging. Finally, he manages to collect his sample, close the valve, and put a stopper in the vial, which is now full of methane gas.
The researchers then trek back to their lab to analyze these samples as part of ongoing field research to fill in a key knowledge gap in climate science: What happens to thawing permafrost in winter?
Hasson, a student researcher with NASA’s Arctic Boreal Vulnerability Experiment, or ABoVE, has been studying Alaskan lakes for three years. His team at the University of Alaska Fairbanks researches how thawing permafrost in Arctic regions contributes to climate change.
Permafrost is ground in mainly polar regions that stays frozen throughout the year, for multiple years. Almost 25% of the Northern Hemisphere contains permafrost. Partially decayed plant matter is trapped within the permafrost, creating a sort of “dirty, dusty, carbon-rich” layer of icy soil, as Hasson described.
Permafrost, he continued in analogy, is like a giant carbon freezer that has been storing organic material for tens of thousands of years. Over the past several decades, as climate change warmed the region, it’s as if someone has left the door open and all the contents of the freezer are thawing. As permafrost thaws, trapped plant matter is broken down by microbes; as a result, carbon dioxide and methane—a greenhouse gas 25 times more potent than the former—are released into the atmosphere.
Thawing permafrost can also collapse, creating depressions that fill with rain and melting snow to form thermokarst lakes, accelerating permafrost thaw and the subsequent release of greenhouse gases.
As the methane bubbles to the surface of lakes in the winter, it freezes in the ice, forming pockets of varying sizes and shapes. These pockets create unique patterns on top of the frozen lakes. In the summer, visitors can watch little bubbles burst at the water’s surface like a hot spring, releasing methane into the atmosphere. This scene illustrates how much the environment here has changed in a region warming twice as fast as the rest of the planet. Only a few decades ago, Arctic winters were colder, many of these lakes didn’t exist and the permafrost was rock solid.
How permafrost behaves in winter has largely been a mystery, but basic physics tells us there’s a lot to learn about its behavior during those darker months. For instance, heat travels slowly through water, so the water in Alaskan lakes holds heat and thaws permafrost partway into the cold season. It’s like lying on the beach in the sun and then walking into an air-conditioned building: your skin still feels warm for a while. Scientists can’t get the whole picture on methane emissions unless they take consistent measurements year-round.
Because planes can only take airborne methane measurements in the summer when there isn’t much snow coverage and because field researchers don’t usually take mid-winter measurements, there is an eight-month gap in the data set – eight months that could completely change how scientists model methane emissions, which have nearly tripled in the past 200 years. These models are crucial in understanding methane’s role in climate change. And that’s why Hasson and his colleagues are in the middle of the Alaskan wilderness: to study methane emissions year-round and provide data for developing climate models.
Hasson and Finke’s university lab will age the gas samples they collect in the field using carbon isotopes to better understand how ancient carbon is being transported into the atmosphere. Even now, in the summertime when airborne measurements are possible, the field team still collects samples at thermokarst lakes and takes them to the lab for analysis.
Hasson said a combination of many different types of measurements and methods is vital to their success. The ABoVE team uses absorption spectrometry to measure methane emissions by shooting lasers through large chambers placed in the water. They also use an insulated sled nicknamed “the coffin” to protect their delicate equipment from the cold while traveling in the field. The team even carries around a giant magnet that can image the ground layers below them, mapping thawing regions of the permafrost. All these methods are the pieces to understanding the puzzle of Arctic permafrost.
Field researchers make observations and collect data so that others can put the pieces in computer models and see the greater picture. “I don’t actually make the predictions,” Hasson said. “I’m just gathering the evidence so that people can put the puzzle together and try to figure out what’s going to happen.”
But “just” gathering the evidence underestimates the task at hand. Even in the cold, Hasson must walk hours to each remote Alaskan lake, pulling his equipment along, following densely forested trails that are too narrow for snow machines.
To save time in a season when daylight is limited and the cold unbearable, Hasson and Hanke, an ABoVE research technician, had the idea to use Hanke’s sled dogs for field travel. The dogs are used to running through winding trails and rough terrain while pulling heavy cargo. And this way, the two researchers get a much-needed break from hauling equipment.
“What’s unique is that [dog mushing’s] original intent was to supply healthcare to remote places in Alaska,” Hasson said. “And now, a century later, we’re staying true to that philosophy and collecting long-term data to know the health of our ecosystems.”
By Katie Orndahl /YUKON AND NORTHWEST TERRITORIES, CANADA/
I spent my summer searching for arctic spirits: barren-ground caribou who are, somehow, both omnipresent and elusive.
My journey, it turns out, would trace the migration route of the Porcupine caribou herd, linking boreal forest and arctic tundra ecosystems unlike any other northern mammal. The wild landscape I traveled forms the northern extent of the North American Cordillera, one of the last intact mountain ecosystems on Earth.
As I prepared, gathering groceries and loading the truck with scientific equipment and camping supplies, I heard whispers of the entire Porcupine herd moving southeast through the Richardson Mountains. Our small research team drove hurriedly north – hoping for a (figurative) collision course with hundreds of thousands of caribou at the Yukon/Northwest Territories border.
Anticipation ran high, but the border was eerily quiet. A gentle breeze blew and the sun shone through thin clouds. We climbed mountain after mountain, rocks clattering underfoot, to scan the horizon. Looking, hoping, wishing, we even tried to conjure up caribou in our minds to fill the vacant tundra. But the landscape remained still and the disappointment palpable.
We sampled vegetation and drove on.
At Imniarvik Base Camp we missed the herd again. Just a few weeks before, the rocky benches above Sheep Creek in Ivvavik National Park had swelled with thousands of caribou. The pulsing mass filled the spaces between spruce trees, blending together first as life personified, and then in death as the roaring Firth River canyon claimed frenzied victims attempting to cross.
Although no longer near, the caribou had made their presence clear – tracks, hair, droppings and browsed willows everywhere we looked. And this, it turns out, was the point. It is hard to be convinced of things we cannot see. As scientists it is our duty to make these things more tangible.
I am a PhD student at Northern Arizona University. My collaborators and I study how millions of migrating caribou interact with their environment: the habitat selection choices the caribou make, as well as the impacts they impart on the landscape. We are particularly interested in how these interactions fit into a complicated web of processes: climate warming, carbon cycling, wildfire and vegetation change. We hope by including caribou we can “animate the carbon cycle” and fill in gaps in scientific understanding about climate change in the Arctic.
This brought me to the Canadian Arctic.
Fieldwork helps us map above-ground biomass of different types of plants in Alaska and northwest Canada. We identify species of shrubs, flowering plants, lichens and grasses/sedges, estimate the amount of ground they cover, measure their heights, and harvest them to weigh in the laboratory. This gives us closest to true estimates of how much plant matter (caribou food) exists in each place.
However, these measurements are small points on a large landscape. I am particularly excited about new technology that can help us map plant matter (“above-ground biomass”) across the entire region. This means future researchers can choose anywhere on a map and understand how much caribou food exists there. And, what’s more, we can link these maps with GPS data from the movements of collared caribou to understand the relationship between caribou density and on the ground vegetation.
For this reason, at each location where we sample vegetation, we also use a drone to collect super high resolution photographs. Not only are these images beautiful, but they also act as a bridge between fine-scale field data and satellite images that cover the whole globe, but contain less detail. We hope drone images might also make future vegetation surveys more efficient.
This summer, we sampled cottongrass tundra as fluffs of wind dispersed seeds floated by, tall willow thickets that bruised our shins and hummed with mosquitoes, and barren ridgelines with little but lichen and resilient dwarf shrubs. Caribou use many different habitats—from the boreal forests of central Alaska to the flat plains of the Yukon North Slope—and our field sites reflect this variety.
At each site, the drone buzzed overhead on a pre-programmed flight, taking detailed photos I’ll use to classify plant cover and create 3D models of vegetation and topography.
Meanwhile, we scurried about on the ground, getting our hands dirty measuring vegetation cover and height, then meticulously harvesting and bagging vegetation.
At each site, I thought about caribou.
Eventually, the midnight sun started dipping below the horizon and the arctic summer sputtered out. As I made the long drive back to Fairbanks, I finally stopped obsessing about finding the caribou. Only then did they appear.
We crawled out of our tents early one morning to see 100 or so caribou nearby. Steaming coffee in hand, our field team watched as the animals we had talked and dreamed about for months grazed peacefully. A sharp intake of breath broke the silence. My colleague pointed into the distance as two small white dots appeared beside the unsuspecting caribou. Moving slowly at first, the wolves broke into a sprint and chased the caribou across the tundra. Kicking up their long legs, the caribou sped away in unison – up a ridge and through a saddle to the other side of the mountains. Defeated, the wolves slowed to a stop and slumped into the grass. This time, caribou won.
Our summer unfolded like a game of hide-and-seek. We found caribou in intricate tracks woven across the landscape, in bits of hair left behind in birch boughs and in willows stripped bare. We found caribou in satiated grizzly bears that gained strength from the unlucky few washed ashore on the Firth River banks. We found caribou in our data which will help us understand how they interact with the changing arctic environment. And finally, we found caribou in the flesh, outrunning two wolves, where the Yukon and Northwest Territories meet.
by Maria-Jose Viñas / NORTHWEST TERRITORIES, CANADA
“Oh, and here’s a black spruce!” exclaimed Charlotte Weinstein, an assistant research scientist at Michigan Tech Research Institute (MTRI), while pointing at a delicate sapling barely the height of a thumb that was almost hidden among the tall grass.
Weinstein and her colleague Shannon Rose, a research fellow at University of Massachusetts-Amherst (UM-A), were painstakingly counting and cataloguing each plant growing in a one-by-one-meter square plot set up in a taiga forest in a remote corner of Canada’s Northwest Territories. The forest burned in 2015, and the wildfire left behind an austere landscape of blackened thin trunks sticking out from the ground, interspersed with patches of exposed limestone rock that had previously been covered by a thick mat of organic soil that burned during the fire.
Four years after the event, vegetation is growing again. But how different will it be from the original taiga forest? Will the new shrubs and trees and the reforming organic soil layer be able to store a similar amount of carbon? Will the changes in plant composition and soil moisture also affect the animal species dependent on the forest?
To answer those questions and more, groups of researchers from all over the United States and Canada are flocking to the Northwest Territories in summer 2019 to carry field work under the umbrella of NASA’s Arctic-Boreal Vulnerability Experiment (ABoVE), a comprehensive field campaign that probes the resilience of Arctic and boreal ecosystems and societies to environmental change – including wildfires.
Weinstein and Rose worked together with Mike Battaglia (MTRI) and Paul Siqueira (UM-A), who took measurements of soil moisture and active layer depth (the top layer of soil that thaws during the summer and freezes in autumn) while the women counted plants. The researchers had all been doing field work for days when a small team of NASA communicators, including this writer, visited them in the field on Aug. 17; they still had about a dozen field sites to explore in the upcoming days. After sampling the burned area, the group moved on to a nearby swath of intact forest – in there, under the canopy of the intact trees, the carbon-rich soil was incredibly squishy and would sink under one’s steps, enveloping my hiking boots in bright green moss.
The active layer and soil moisture measurements were repeated in the unburned forest, but this time the researchers were also gauging plant biomass. Weinstein and Rose started measuring the diameter and height of all trees within a 10-by-10-meter square, while Battaglia dug a pit and extracted a large cube of dark soil to measure and take samples of the organic layers. Because the soil is frozen most of the year in the Arctic and boreal regions, the organic matter within doesn’t decompose. As a result, soils in those parts of the world often sequester more carbon than the trees and shrubs growing on them.
After their field campaign, the team’s measurements of plant composition, biomass, soil moisture and active layer will become part of ABoVE’s wealth of publicly-shared data.
“Our end game is to incorporate all field and remote sensing measurements into computer models to understand the long-term change of the land,” Battaglia said.
by Joanne Speakman / NORTHWEST TERRITORIES, CANADA /
My name is Joanne Speakman and I’m from the Northwest Territories (NT) in Canada. I’m indigenous to the Sahtu Region and grew up in Délįne, a beautiful town of about 500 on Great Bear Lake. Now I live in Yellowknife, NT, and study environmental sciences at the University of Alberta. I was a summer student this year with the Sahtu Secretariat Incorporated (SSI), an awesome organization in the NT that acts as a bridge between land corporations in the Sahtu. My supervisor, Cindy Gilday, helped organize a once-in-a-lifetime opportunity for me and a fellow student from Délįne, Mandy Bayha, to fly with NASA. It was a dream come true.
One of NASA’s projects is called the Arctic-Boreal Vulnerability Experiment (ABoVE), which is studying climate change in the northern parts of the world. People from the circumpolar regions have seen firsthand how drastically the environment has changed in such a short period of time, especially those of us who still spend time out on the land. Weather has become more unpredictable and ice has been melting sooner, making it more difficult to fish in the spring. Climate change has also contributed to the decline in caribou, crucial to Dene people in the north, both spiritually and for sustenance.
Studies like ABoVE can help explain why and how these changes are happening. Along with traditional knowledge gained from northern communities, information collected by ABoVE can go a long way in helping to protect the environment for our people and future generations.
Wednesday, August 22, 2018:
It was exciting to meet the ABoVE project manager, Peter Griffith, and the flight crew because it’s amazing what they do, and to fly with them was an incredible opportunity to learn from one another. Although we were from different parts of the world, at the end of the day we are all people who care about taking care of the environment. We flew on a Gulfstream III jet to survey the land using remote sensing technology. We flew from Yellowknife to Kakisa, Fort Providence, Fort Simpson and then back to Yellowknife.
During the flight, crew ran the remote sensing system and they explained to us how it works. It got complicated pretty quickly, but from what I understood, a remote sensor is attached to the bottom of the plane and sends radio waves to the ground and bounce back, providing information about the land below and how it is changing from year to year.
August 24, 2018
NASA’s also working on building a satellite called the NASA-ISRO Synthetic Aperture Radar, or NISAR, which will help study the effects of thawing permafrost. Two of the lead scientists working on NISAR are Paul Siqueira and Bruce Chapman. While they were in Yellowknife, Mandy and I got invited to join them for a day to help collect field data.
We met with Paul and Bruce early in the morning and then drove out on the Ingraham Trail until we reached a small, marshy lake. We got out and walked along the lake’s edge, making measurements of the amount of marshy vegetation from the shore
to the open water, an area that I learned is called inundation. We used our own estimations and also a cool device that uses a laser to tell you exactly how far away an object is. Paul and Bruce will use the information we collected that day to figure out the best way to map wetlands, which will help the ABoVE project study permafrost thaw and help with development of the NISAR satellite by comparing our results to satellite images of the area.
In the afternoon, we surveyed a second lake, this time using a canoe. The sun came out and we saw ducks, a juvenile eagle, and many minnows swimming around. Nothing’s perfect, but this day was close to it and we learned a lot along the way.
Meeting and spending time with the NASA team, especially Bruce, Paul, and Peter, was the highlight of the two days. They’re incredibly kind and thoughtful and took the time to share their knowledge with us. ABoVE is a 10-year program and I hope there will be many more opportunities for northern youth to participate in such an exciting, inspiring project. There is so much potential out there. Thanks again for an amazingly fun learning experience!
As I walk up the Alpine Trail in Denali National Park, I can see the vegetation changing before my eyes. Deciduous plants, like willows and smaller shrubs, start huge, as tall as my head and shoulders. But as the trail leads up, and as the altitude grows, the vegetation shrinks.
Over the course of the roughly 1,300-foot elevation gain, the plant life gets shorter and shorter until suddenly it’s almost gone—we’ve reached the tundra. By climbing up the side of this hill, we’ve mimicked traveling north into the colder parts of the Arctic, reaching the tundra much faster.
Tundra is like the Arctic’s desert: an expanse of treeless land with little available water. Most water in the tundra is below the ground in a layer of continuously frozen soil known as permafrost. Between the tundra’s low temperatures and the permafrost, it’s not a hospitable location for much plant life.
On the tundra, Peter Griffith, project manager for the Arctic Boreal Vulnerability Experiment (ABoVE), points out the same shrubs we encountered lower down, although here, instead of towering over our heads, they’re only a few inches above the ground.
But that could be changing. It’s one element of the ABoVE team’s research: understanding how native Arctic vegetation responds to a warming climate.
Griffith describes the shrubs as “ready and waiting to march up the mountain.” They’re opportunistic plants, and all it takes is a little warmth and thawed ground for them to dig in and start growing larger, a process known as “shrubification” and one of the causes of the greening trends seen from long-term satellite records.
As greenhouse gases change Earth’s climate, the Arctic is warming much faster than the rest of the world. And the changes are staggering. Permafrost is thawing, and the shrubs aren’t the only ones taking advantage. Within the soil, bacteria are growing and beginning to metabolize organic matter that’s been frozen in permafrost for thousands of years.
As they feast, bacteria release carbon dioxide and methane, which are released into the air. Plants like shrubs use carbon dioxide to grow even faster. In some ways, it seems like a race.
Will the bacteria respire more carbon dioxide than the growing plants can absorb? At some sites, that already seems to be the case. How this race plays out across the Arctic is another question the ABoVE team is investigating.
Using measurements of carbon dioxide and methane taken from flux towers sitting directly on the tundra, to instruments mounted on airplanes and satellites in low Earth orbit, NASA scientists are finding out how the land ecosystem influences the atmosphere in a greening Arctic, and what the consequences are for not only the Arctic but also the world.
The Arctic Boreal and Vulnerability Experiment (ABoVE) covers 2.5 million square miles of tundra, forests, permafrost and lakes in Alaska and Northwestern Canada. ABoVE scientists are using satellites and aircraft to study this formidable terrain as it changes in a warming climate.
In some ways, NASA’s DC-8 feels like a commercial airplane, with its blue leather seats and tiny bathrooms in the back. But once the plane starts to spiral down over Arctic towns, I remember I’m riding on a flying laboratory studying the amount and distribution of carbon dioxide and methane in the atmosphere.
Over the course of these big, looping spirals, the plane descends from a cruising altitude of about 30,000 feet down to just about 100 feet above the ground. The pilots fly us over the runway, as though we’re about to land, before pulling up at the last minute and returning to the sky, a maneuver known as a “missed approach.”
The whole process of spiraling down is a little scary the first few times we do it, but it’s necessary as an accuracy check for our science instruments, and by the third or fourth spiral down, it’s become a somewhat routine experience for me.
From the windows, I get a good look at the varied Arctic landscapes—twisting, braided rivers, carpets of spruce trees, and broad expanses of flat tundra all spread out underneath us. Each of those landscapes offers interesting scientific insights into how carbon emissions are changing as the climate warms.
The plane is carrying five instruments designed to measure the spatial distribution of carbon dioxide from the air. They’re placed along the plane in place of some the seats and are operated by scientists monitoring screens mounted on their sides.
Someday, a descendent of these instruments will fly on the Active Sensing of Carbon dioxide Emissions over Nights, Days and Seasons, or ASCENDS, satellite, and the spiraling helps the researchers verify their measurements by flying right through the columns of air they’re studying from far above.
Jim Abshire is the project lead for the ASCENDS campaign. He sits near the front of the plane, plugged into the communications system and periodically checking with each instrument’s operators, making sure everything is running smoothly and requesting the occasional altitude change from the plane’s navigators.
He describes the spiral down maneuvers as a check on the lidar measurement systems, specifically ensuring that the instruments are sensitive enough to make precise measurements from space.
As Earth’s climate continues to warm, the Arctic warms much faster, and the subsequent changes in the Arctic regions are resulting in some soils releasing more carbon. More carbon in the atmosphere traps heat, causing more warming, which in turn causes the Arctic soils to release even more carbon, a process called the carbon-climate feedback.
Understanding this vicious cycle is one of the primary goals of the Arctic Boreal Vulnerability Experiment (ABoVE), a NASA campaign that includes the ASCENDS flights, as well as many other experiments, all designed to better understand how the rapid environmental change in the Arctic regions of the world impact ecosystems and society.
At first glance, it looks like a typical, picture-perfect lake. But scan the reeds along the shore of this pool on the outskirts of Fairbanks, or glance at the spruce trees lining the banks, and you notice something different is going on.
Bubbles. There are bubbles popping up among the reeds, like bubbles from a fish tank aerator. A couple clusters, steady streams of small half-circles, vent near the shore. Then another group appears in deeper water.
And the trees. Some of them are not growing in the directions trees normally do. They stick out drunkenly over the lake, then take a turn upwards at the top.
The explanation for both of these features is in the soil. Permafrost—soil that remains frozen year-round—lies underneath the moss, needles and topsoil of the site. As that permafrost thaws, the ground above it can sink, knocking trees askew and forming pools of water called thermokarst lakes.
“The carbon locked in permafrost for thousands of years is released to the lake bottom,” said Prajna Lindgren, a postdoctoral researcher at the University of Alaska, Fairbanks, Geophysical Institute.
These lake beds, she explained, provide a perfect environment for microbes to eat up the carbon released from the thawing permafrost. This produces methane—a potent greenhouse gas that is released in bubble seeps. As part of the NASA-funded Arctic Boreal Vulnerability Experiment, or ABoVE, Lindgren and her colleagues are studying these seeps and mapping how thawing permafrost is affecting the changing lake edges.
“We’re trying to establish the amount of methane that’s released from these lakes,” she said.
To do that, the scientists are combining old aerial photos with satellite images and new surveys of lakes across Alaska. They’re looking at how the shapes and sizes of lakes are changing over time, which is an indication of where permafrost thaw is altering the landscape. Then, they examine how changing landscapes are associated with the methane seeps. In the fall, as soon as the lakes freeze over, the bubble-measuring fieldwork begins.
“If there’s no snow on the lake and its just black ice, when you walk out you see distinct bubbles in the lake ice,” Lindgren said. The methane bubbles get trapped in the ice, fusing together in pancake shapes, that the researchers can plot and measure.
“We see a lot of these seeps clustered where the lakes are changing,” she said. The next steps will be to estimate methane release based on the extent of lake changes. And for lakes beyond the researchers’ reach, such as those in remote areas of Alaska and northwestern Canada, the goal is to estimate methane release based on how the lakes are changing, as seen in satellite images.
A new study, funded in part by ABoVE, compared old aerial photos from the 1950s with recent satellite images to measure changes in lake outlines, for example. Using this information, methane measurements, radiocarbon dating and other techniques, the scientists calculated how much old carbon, stored for thousands of years in the permafrost, has been released over the past 60 years.
“What we’re going to do is walk back in time,” said Matthew Sturm, standing in front of a doorway that led into a hillside north of Fairbanks, Alaska.
Through the doors was a tunnel that provides access to the Alaska of 40,000 years ago, when bison and mammoths foraged in grassy valleys. Now, however, the grasses and the animal bones are frozen in the ground in the Permafrost Tunnel.
The tunnel, run by the U.S. Army’s Cold Regions Research and Engineering Laboratory, was dug in the 1960s and is the site of much research into permafrost—ground that stays frozen throughout the year, for multiple years. Sturm, a professor and snow researcher at the University of Alaska, recently led a group with NASA’s Arctic Boreal Vulnerability Experiment (ABoVE) to the site. The walls of the tunnel expose the silt, ice, and carbon-rich plant and animal matter that has been frozen for tens of thousands of years.
“It’s a legacy of the Ice Age,” Sturm said. Roots of long-buried grasses hang from the ceiling, in a few places bones of Pleistocene mammals are embedded in the wall.
What will happen to the carbon contained in permafrost in the Alaska interior and elsewhere in the northern latitudes is a major question for NASA’s ABoVE campaign, which is studying the impacts of climate change on Alaska and northwestern Canada. Temperatures are rising in the Arctic region, which means permafrost is thawing at faster rates—and when it thaws, it releases carbon dioxide or methane into the atmosphere.
One ABoVE project is taking steps to monitor the temperatures of the permafrost across Alaska to see how far below the surface it is frozen and whether the temperatures of the soil layers are changing.
“We’ll get temperature data across large territories to supplement the existing data,” said Dmitry Nicolsky, with the University of Alaska, Fairbanks. Most of the existing data is along easy-to-access roads—but there aren’t many roads in Alaska. Nicolsky and his colleagues are working with researchers at USArray, which is establishing earthquake-monitoring stations across the state. Those crews are also drilling about 20 boreholes for thermometers this year, with more planned.
Nicolsky has been getting the instruments ready for deployment. Crews will install lines that have six temperature sensors at six different depths, from just below the top mossy layer to more than 6.5 feet below the surface. They’ll take readings several times a day for three to five years to help the scientists get a more complete picture of how temperatures in Arctic soil are changing.