Lasers and Bubbles: Solving the Arctic’s Methane Puzzle

Phil Hanke (left) and Katey Walter Anthony determine if an Alaskan lake contains methane by igniting the gas flux. Credits: University of Alaska Fairbanks/Nicholas Hasson

by Emily Fischer

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.

Methane bubbles freeze in the ice as they leak from thawing permafrost beneath Alaskan lakes. These bubbles are measured by researchers to determine the amount of methane released. Credits: University of Alaska Fairbanks/Nicholas Hasso

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.

Methane bubbles freeze in the ice as they leak from thawing permafrost beneath Alaskan lakes. Credits: University of Alaska Fairbanks/Nicholas Hasson

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.”

ABoVE field researchers must navigate rough boreal terrain on foot or by dog sled to access remote permafrost lakes, pulling 200 pounds of scientific equipment behind them. Credits: University of Alaska Fairbanks/Nicholas Hasson

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.


ABoVE field researchers must navigate rough boreal terrain on foot or by dog sled to access remote permafrost lakes, pulling 200 pounds of scientific equipment behind them. Credit: University of Alaska Fairbanks/Nicholas Hasson

“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.”

Phil Hanke (left) and Nicholas Hasson measure methane seeps from a permafrost lake near Fairbanks, Alaska, using equipment hauled on an insulated sled, nicknamed “the coffin.” Credits: University of Alaska Fairbanks/Nicholas Hasson

Chasing Caribou Across a Changing Arctic

Katie Orndahl (left) and Rachel Pernick (right) scaling rocky slopes in search of caribou near the Yukon/Northwest Territory border. Photo credit to Aerin Jacob
Katie Orndahl (left) and Rachel Pernick (right) scaling rocky slopes in search of caribou near the Yukon/Northwest Territory border. Photo credit: Aerin Jacob


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.

The Firth River is a formidable obstacle for Porcupine caribou on their yearly migration. Photo credit: Katie Orndahl
The Firth River is a formidable obstacle for Porcupine caribou on their yearly migration. Photo credit: Katie Orndahl

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.

We felt the Porcupine herd’s presence in the things they left behind: tracks, dung, bones, antlers, hair, and signs of browse. Photo credits: Katie Orndahl and Aerin Jacob
We felt the Porcupine herd’s presence in the things they left behind: tracks, dung, bones, antlers, hair, and signs of browse. Photo credits: Katie Orndahl and Aerin Jacob

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.

The drone witnessed picked up signs of caribou, too. This drone image shows caribou trails weaving through spruce near Sheep Creek in Ivvavik National Park. Credit: Katie Orndahl
The drone picked up signs of caribou, too. This drone image shows caribou trails weaving through spruce near Sheep Creek in Ivvavik National Park. Credit: Katie Orndahl

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.

Using an iPad, Katie (left) and Rachel (right) monitor the drone as it completes its flight in a cottongrass tundra. hoto credit: Aerin Jacob
Using an iPad, Katie (left) and Rachel (right) monitor the drone as it completes its flight in a cottongrass tundra. Photo credit: Aerin Jacob

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.

Katie (left) and Rachel (right) carefully recording vegetation species, cover, and height on line transects. Photo credit: Aerin Jacob
Katie (left) and Rachel (right) carefully recording vegetation species, cover, and height on line transects. Photo credit: Aerin Jacob
Our field sites varied from luscious cottongrass …
Our field sites varied from luscious cottongrass … Photo credit: Katie Orndahl
… to bare rocks and hardy lichen …
… to bare rocks and hardy lichen … Photo credit: Katie Orndahl
… to thick riverside shrubs
… to thick riverside shrubs. Photo credit: Katie Orndahl

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.

Hundreds of caribou flee pursuing wolves near the Yukon/Northwest Territory border. Photo credit: Laurence Carter
Hundreds of caribou flee pursuing wolves near the Yukon/Northwest Territory border. Photo credit: Laurence Carter

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.

Rachel (left) and Kayla Arey (right) soak in our first caribou sighting as summer winds down in the Arctic. Photo credit: Laurence Carter
Rachel (left) and Kayla Arey (right) soak in our first caribou sighting as summer winds down in the Arctic. Photo credit: Laurence Carter

Grass, Shrub, Grass… Tree! Measuring Regrowth in a Burned Forest

A black spruce sapling growing among grass in an area of taiga forest that burned in 2015. Credits: NASA/Maria-José Viñas


“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?

Charlotte Weinstein (right) and Shannon Rose catalogue all growing in a one-by-one-meter square plot. Credits: NASA/Maria-José Viñas

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.

Mike Battaglia holds up a block of carbon-rich soil extracted from an unburned forest near Kakisa, Northwest Territories, Canada. Credits: NASA/Maria-José Viñas

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.

Students Traverse Land, Air, and Water in Canada with NASA’s ABoVE

Joanne Speakman helps scientists map wetlands near the city of Yellowknife in the Northwest Territories, Canada. Credits: Paul Siqueira


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:

Joanne Speakman sits behind the pilots during takeoff. Credits: Mandy Bayha

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.

The pilots, Terry Luallen (left) and Troy Asher, make flying look easy. It was remarkable to see them work and to listen to them over the headset, says Speakman. Credits:
At work in the Gulfstream III jet are flight engineer and navigator Sam Choi from NASA’s Armstrong Flight Research Center and radar operator Tim Miller from NASA’s Jet Propulsion Laboratory. Credits: Joanne Speakman
From left: NASA pilot Terry Luallen, Mandy Bayha, NASA ABoVE Chief Support Scientist Peter Griffith, Joanne Speakman, NASA pilot Troy Asher.

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.

Rock climbing isn’t the easiest in rubber boots, but Joanne Speakman and Paul Siqueira make it safe and sound. Credits: Mandy Bayha

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

Joanne Speakman admires a stunning view after the climb. The Northwest Territories has so many hidden gems, she says. Credits: Paul Siqueira

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.

Mandy Bayha and Joanne Speakman use their canoeing skills. With them is NASA scientist and engineer Bruce Chapman, who Joanne is excited to learn has spent time studying the surface of Venus. Credits: Joanne Speakman
University of Massachusetts Amherst scientist Paul Siqueira enjoys the last canoe ride of the day with Joanne Speakman and Mandy Bayha. Credits: NASA/Bruce Chapman

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!

In Arctic Tundra, It’s Getting Easy Being Green

A view of tundra and native spruce trees in the valley. Credit: NASA/Katy Mersmann


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.

In some places, the trail bisects the hill, with large deciduous plant life on one side and tundra on the other. Credit: NASA/Katy Mersmann

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.

Shrubs that grow as tall as a person further down the hill carpet parts of the tundra, waiting to take advantage of slightly warmer temperatures and more available water. Credit: NASA/Katy Mersmann

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.

Taking in Some Arctic Air

As the DC-8 spirals closer to Inuvik, Canada, a view emerges of the huge Mackenzie River and the standing water that flanks it. Credit: NASA/Katy Mersmann


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 DC-8 crew take turns flying out from Fairbanks, Alaska. Credit: NASA/Katy Mersmann

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.

As the DC-8 flies low over McGrath, Alaska, a tableau appears of spruce trees lining the Kuskokwim River. Spruce trees are native to the Arctic forest regions, but after frequent wildfires, some have been replaced by deciduous plants. Credit: NASA/Katy Mersmann

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.

Mapping Methane in a Bubbling Arctic Lake

by Kate Ramsayer / FAIRBANKS, ALASKA /

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.

Methane bubbles pop on the surface of a lake near Fairbanks, Alaska. Thawing permafrost in the lakebed soils releases old carbon, which microbes eat up and turn into methane. Credit: NASA/Kate Ramsayer

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.

A lake near Fairbanks shows signs of thawing permafrost below the surface – including "drunken trees" that tip over as the soil shifts around its roots. Credit: NASA/Kate Ramsayer
A lake near Fairbanks shows signs of thawing permafrost below the surface – including “drunken trees” that tip over as the soil shifts around its roots. Credit: NASA/Kate Ramsayer

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.

Methane bubbles in a lake.
A methane seep releases bubbles in the grasses close to the shore of a lake near Fairbanks, the site of thawing permafrost. Credit: NASA/Kate Ramsayer

“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.

Burrowing into the Arctic’s Carbon Past and Future

The Permafrost Tunnel provides a look back in time, allowing for research into the frozen ground of interior Alaska. Credit: NASA/Kate Ramsayer
The Permafrost Tunnel provides a look back in time, allowing for research into the frozen ground of interior Alaska. Credit: NASA/Kate Ramsayer

by Kate Ramsayer / FAIRBANKS, ALASKA /

“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.

Scientist in a permafrost tunnel
Matthew Sturm points to some grasses and sticks that were buried during the Ice Age and frozen in the ground and now exposed in the ceiling of the permafrost tunnel. Credit: NASA/Kate Ramsayer

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.

Man working outside
Dmitry Nicolsky demonstrates how sensors are inserted into a borehole to measure the temperatures of layers of soil and permafrost at different depths. Credit: NASA/Kate Ramsayer

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.  

Taking Measure of a Remote Slice of Alaskan Forest

Kate Legner points out the next tree in the survey site as other crew members measure key information about the vegetation in a 53-foot diamter plot. Credit: NASA/Kate Ramsayer
Kate Legner points out the next tree in the survey site as other crew members measure key information about the vegetation in a 53-foot diamter plot. Credit: NASA/Kate Ramsayer

by Kate Ramsayer / SALCHA, ALASKA /

In a birch forest in interior Alaska’s Tanana Valley, there’s a stake with pink plastic tape attached. More than three decades ago, a plane flew over it to take stereoscopic pictures of the surrounding plot, and scientists trekked out to survey the trees and vegetation. Now, scientists are re-flying and re-surveying the site, using advanced airborne instruments and satellite images to track changes in interior Alaska.

“This is going to be 10.3,” called out Sean Cahoon, a scientist with the University of Alaska, Anchorage. He was standing at the end of a tape measure radiating out from the stake, using another tape measure to check the diameter of the base of a birch tree.

Birch trees, numbered in yellow, have been measured as part of the site survey. Credit: NASA/Kate Ramsayer
Birch trees, numbered in yellow, have been measured as part of the site survey. Credit: NASA/Kate Ramsayer

Kate Legner, with the University of Washington in Seattle, recorded the number as well as the diameter at breast height, the distance from the stake, and the azimuth (angle from due north) of the tree’s location.

“That’s all you need to recreate this whole area,” Legner said. The area in question is a circle with a 53-foot radius out from the stake. Mostly birch, with a few aspen and white spruce trees, just sparse enough to let some sun filter through to shrubs, seedlings, moss and lichens thick on the ground.

ABoVE scientists measure a field site in interior Alaska's Tanana Valley, which has been monitored from the ground, airborne instruments and satellites to track changing ecosystems. Credit: NASA/Kate Ramsayer
ABoVE scientists measure a field site in interior Alaska’s Tanana Valley, which has been monitored from the ground, airborne instruments and satellites to track changing ecosystems. Credit: NASA/Kate Ramsayer

The recreation of this and other plots in the Tanana Valley is a key part of the NASA-funded Arctic Boreal Vulnerability Experiment, or ABoVE. Scientists will compare ground surveys to surveys from 35 years ago, along with aerial photos from similar time periods. They’ll also incorporate data from NASA Goddard’s Lidar, Hyperspectral, and Thermal (G-LiHT) airborne imager, which provides vegetation heights and composition information along sample strips throughout the valley.  The times between these ground and airborne observations are filled by periodic image data from Landsat satellites. Landsat provides a more continuous record of change, but the coarse resolution of the data does not capture tree-scale information.   

“Our overall objective is to make use of a really rich historical inventory dataset that we have available,” said Hans Andersen, an ecologist with the U.S. Forest Service and co-investigator on the project. “We’ll be interested in changes in the vegetation cover that could be due to climate change over that period of time.”

The different sources of data complement each other, he said. Ground surveys allow researchers to identify and count individual trees, while aerial photos can cover more ground. The strips of G-LiHT data, covering the valley and collected by NASA Goddard’s Bruce Cook, who is leading the project, provide high-resolution data of tree heights, species composition and moisture conditions of the site.

Every time a Landsat satellite passes overhead and captures a cloud-free image, the team adds that to the data record as well. It’s not a coincidence that the 53-foot-radius plot matches up with a single Landsat pixel, Andersen said.

And it’s not just tree composition that the crew is interested in. As Legner and Cahoon were measuring and marking trees, Andersen and the fourth member of the survey crew were nearby digging a hole, collecting soil samples in plastic zippered bags.  

“The soil samples are all about the carbon,” said Robert Pattison, with the U.S. Forest Service’s Anchorage Forestry Sciences Laboratory. “For interior Alaska, it’s really the biggest story.”

One new element to the survey protocol: taking soil samples at different depths to check carbon content. Credit: NASA/Kate Ramsayer
One new element to the survey protocol: taking soil samples at different depths to check carbon content. Credit: NASA/Kate Ramsayer

This summer, the crew is refining their field sampling protocols and investigating “road-accessible” sites. The birch site was a half-mile scramble up a hillside covered in prickly bushes and thick shrubs, with fallen trees and branches providing additional obstacles.

Next year, the crew will use helicopters to get to even more inaccessible sites across the Tanana Valley. They’ll survey about two dozen representative sites, measuring trees, soils and other sources of carbon, with the goal of making computer models to relate those findings to sites across the valley.

“The end product is essentially an estimate of carbon in various places across the entire Tanana,” Andersen said.

Living Off the Land in a Changing Arctic Climate

Moose are one of the main resources for subsistence hunters in Alaska. Areas that are recovering from a low-severity wildfire can attract the ungulates. “If we didn’t have fires ripping through, we would have fewer moose walking through here and fewer full freezers,” said Todd Brinkman, an assistant professor at the University of Alaska, Fairbanks. Credit: NASA/Kate Ramsayer

by Kate Ramsayer / FAIRBANKS, ALASKA /

Scrambling up the bank of the Tanana River south of Fairbanks, Theresa Hollingsworth was looking for examples of how the forest recovers after a wildfire. She found an unexpected sweet surprise.

“Blueberries!” she yelled from the banks.

Gathering handfuls, she instantly planned a return trip later in the week to go picking. “You fill your freezer with as many berries as you can.”

It’s a way of life for many Alaskans, said Hollingsworth, a research ecologist with the U.S. Forest Service’s Pacific Northwest Laboratory. People have favorite—often secret—berry spots they go back to year after year. They also hunt and fish, stocking freezers with moose and salmon and other game.

For many Alaskans, summer is time to stock freezers with blueberries. Credit: NASA/Kate Ramsayer
For many Alaskans, summer is time to stock freezers with blueberries.
Credit: NASA/Kate Ramsayer

Many of the rural villages in this giant state—more than twice the size of Texas—aren’t connected with roads, said Todd Brinkman, an assistant professor at the University of Alaska, Fairbanks.

“The road network for a lot of these rural communities is on the rivers, or trail networks through the woods,” he said. “That’s their access to the grocery stores—grocery stores being the forests around them.”

But many residents are reporting that the changing environment is creating obstacles to how they reach these resources. So Brinkman and Hollingsworth are working on a research project with the NASA-funded Arctic Boreal Vulnerability Experiment, or ABoVE, to investigate how access to game, berries, and neighboring villages is changing in a warming climate.

In March, Brinkman gave camera-equipped GPS units to subsistence hunters in eight or so villages across Alaska. Over the next year, the residents will document anything that blocks or hinders their travel, whether it’s an early thaw of river ice, a wildfire, a trail sunk by thawing permafrost or something the researchers haven’t yet thought of.

“We’re letting the subsistence users really drive the research,” Hollingsworth said.

In one area, for example, women were wary of collecting blueberries in their traditional spot, since a wildfire had torn through and left dead trees in danger of toppling over. Wildfires can also change the types of plants that grow back, which in turn could impact the wildlife as well as the people living nearby.

Scientist looks at plants.
Theresa Hollingsworth examines the moss and lichens on a forest floor. Credit: NASA/Kate Ramsayer

Rural residents have also noted changes to the rivers, Brinkman said. People boat along rivers in summer and use them as a snowmachine trail in winter, but the in-between periods while the ice is breaking up or forming make travel incredibly difficult. If a warming climate means early ice break-up, it’s significant to people who depend on that river, he said.

The character of some rivers is also changing. Residents are noting that the permafrost in the banks is thawing, leading to erosion. More erosion means wider rivers, which also means shallower rivers.

“Where the permafrost is exposed, it’s challenging navigating on a lot of these river systems,” Brinkman said.

A river.
The Tanana River south of Fairbanks, Alaska. For many rural residents, rivers are an important transportation route.
Credit: NASA/Kate Ramsayer
A riverbank.
Brinkman looks at a riverbank of thawing permafrost, which is dripping water and sending clumps of soil into the river. Credit: NASA/Kate Ramsayer

After a year’s worth of these disturbances are recorded, Hollingsworth and others will examine the sites. They’ll analyze remote sensing images, including those from Landsat satellites, for before-and-after comparisons. They’ll visit the site, inventory the ground cover and trees and take soil samples and other measurements to get a sense of what is happening with the ecosystem. The researchers can also use remote sensing images to relate changes to access in one place to changes that could be happening in similar ecosystems.

And they’ll talk with the residents about how these changes are impacting their everyday lives, Brinkman said. “We’ll start to understand the types of disturbances we should dig into.”