The Unseen World of Climate Change
The Arctic tundra of Alaska features a picturesque landscape, teeming with plants and wildlife. But below ground lies a significant threat to the environment. As temperatures rise around the globe, layers of soil known as permafrost, which have been frozen for up to thousands of years, are beginning to thaw. And with that, threatening to release massive amounts of trapped greenhouse gases into the atmosphere. To study these dramatic changes, the U.S. Department of Energy launched the Next-Generation Ecosystem Experiments, or NGEE Arctic, project. NGEE brings together an interdisciplinary team to study the complex scientific processes that occur as the permafrost starts to thaw. In this episode, you'll hear members of the team discuss their research, what it's like to work in the Arctic tundra - including a wildlife story or two.
COLLEEN IVERSEN: That’s climate change, right? How much greenhouse gases are going into and staying in the atmosphere.
PETER THORNTON: It’s daunting to get that realization. These changes are real and happening quickly on a very large scale.
STAN WULLSCHLEGER: There is a tipping point that comes with the freezing point of water. And when we reach that tipping point, the Arctic begins to unravel.
JENNY: Hello everyone and welcome to The Sound of Science.
MORGAN: The podcast highlighting the voices behind the breakthroughs at Oak Ridge National Laboratory.
MORGAN/JENNY: We’re your hosts – Morgan McCorkle and Jenny Woodbery.
JENNY: Imagine yourself in the middle of the Arctic tundra of Alaska. Before you is a sprawling landscape, untouched by human development.
MORGAN: The air is frigid and low-lying vegetation surrounds your feet, covering the ground for miles on end.
JENNY: It’s a desolate place where you’re more likely to run into a musk ox or a polar bear than you are another person.
MORGAN: And depending on the time of year, you may not even see the sun set.
JENNY: In a place so beautiful and serene, it may be hard to believe that below ground lies a significant threat to the environment.
MORGAN: As temperatures rise around the globe, layers of soil known as permafrost, which have been frozen for up to thousands of years, are beginning to thaw.
JENNY: And with that, threatening to release massive amounts of trapped greenhouse gases into the atmosphere.
MORGAN: And instead of vehicles, factories and power plants, we’re talking about soil, roots and microbes.
JENNY: This is the unseen world of climate change.
STAN WULLSCHLEGER: High-latitude ecosystems, most notably Arctic tundra, are warming at a faster rate, in fact, twice as fast as the planet is warming. And because of that, there is a concern that massive amounts of carbon that are stored in frozen soils or permafrost might be released to the atmosphere as carbon dioxide or methane.
MORGAN: That’s Stan Wullschleger. He’s the associate laboratory director for ORNL’s Biological and Environmental Systems Science Directorate. Since 2012, he’s been leading research in Alaska to investigate the changes happening in this delicate landscape.
JENNY: The project is called Next-Generation Ecosystem Experiments, or NGEE Arctic. It’s a collaborative effort between four Department of Energy national laboratories and the University of Alaska Fairbanks.
MORGAN: NGEE brings together an interdisciplinary team to study the complex scientific processes that occur as the permafrost starts to thaw.
WULLSCHLEGER: Almost right from the beginning, in 2012, we knew that thawing permafrost would be an important topic to study. The amount of carbon stored within those soils, the release of that CO2 and methane, was important. And so, we've spent a lot of time gathering information in order to best understand and represent those processes in sophisticated computer models. Now early on, we understood that thawing permafrost, for reasons of greenhouse gas emissions, was important. What we didn't know and what came as a surprise to us was that the Arctic landscape is held together by frozen soils and ice. And when those soils warm up above the freezing point, the Arctic landscape begins to unravel.
JENNY: These changes can have pretty drastic effects on the terrain in a rather short amount of time.
WULLSCHLEGER: Over short periods of time, a year or two, with rising temperatures, we can actually see a transformation of Arctic landscapes, the soils thaw, that ice melts, the ground begins to sink and subside. And rather quickly the landscape begins to take on hummocks and hollows, rims and troughs, a distribution of wet and dry in a patchwork mosaic across the landscape.
MORGAN: To monitor and study these changes, the NGEE team journeys to two field sites each year – with the exception of 2020 due to the COVID-19 pandemic – to gather data that inform climate models, which can help predict the future of the landscape – and the world.
COLLEEN IVERSEN: Part of what we do in our research that's funded by the Department of Energy is to try to make observations of the natural world that can inform the representation of the natural world in mathematical models, because we use those models to predict what might happen in the future so that society can make decisions about the future. And so, the Arctic tundra tends to be a place that is just really poorly represented in our current generation of mathematical models that are predicting the future. We do a really good job of measuring the temperate forest because that's where a lot of us live. And so, we tend do a great job of representing the temperate forests in these mathematical models. But we have less observations of what's happening in the Arctic tundra, because it's remote, because it's hard to get to, because we don't live there.
JENNY: That’s Colleen Iversen. She’s a senior staff scientist in ORNL’s Environmental Sciences Division.
MORGAN: As an ecologist on the NGEE team, you’re likely to find her digging in the Arctic tundra to collect soil samples and measure plants and their root systems.
JENNY: The project brings together experimentalists like Colleen and computer modelers to help predict the future of the changing Arctic landscape.
MORGAN: As you can probably guess, establishing a world-class research project in the Arctic tundra is no easy feat.
WULLSCHLEGER: During our first trip to Alaska, we had assembled our leadership team into a small plane, and our pilot hopped our way northward from one remote airfield to another. And I just recall, the remote feeling of isolation, as we landed the plane in those environments, and how daunting it was to actually think that we were going to execute sophisticated research in a large team in these really isolated and remote environments.
JENNY: The team was looking for field sites with a lot of variation in the terrain and vegetation so they could get a closer look at the relationship among the plants, soil and microbes in these areas.
MORGAN: They settled on two locations – one near Utqiagvik (UUT-kee-AH-vik), which is the northernmost city in the United States, and the other about 500 miles south outside of Nome on the Seward Peninsula.
IVERSEN: One of the things that was the most surprising and sort of delightful about going to the Arctic tundra was how much variation there is over really small spatial scales and over really big spatial scales. I always show people when I’m giving a talk, I show them a picture of what the tundra looks like from the boardwalk in Utqiagvik. So, you could walk out across this boardwalk, and you can look out and you just see what looks like green slime, just like kind of nothing. Like these plants, like hugging the surface of the soil. But when you get down into it, you put your nose into it, there's many, many different kinds of plants there. But they have evolved in this sort of harsh environment. And so, they’re hugging the ground; it’s hard to see that variation until you get up close. But then if you come more south, towards Nome, Alaska, where another one of our field sites is located, the shrubs that live there, a similar kind of plant, are taller than me. And so, there's this really interesting gradient of plants that live across this latitudinal gradient for Alaska, which is where we work on the NGEE Arctic project, but also across the Arctic tundra, sort of circling the top of the world.
JENNY: For almost a decade, these field sites have produced a wealth of data that has helped scientists develop better climate models.
MORGAN: But before we talk about the models, let’s dig in – no pun intended – to the research the team is doing in the field to gather this data.
JENNY: We’ll start with plants. As Colleen explains, the variation in plant life helps the team get a better understanding of the changes happening underground.
IVERSEN: The reason it's important to understand these plant characteristics is because depending on what plants are on the landscape, it can affect soil temperatures, which means it can affect permafrost thaw, which means it can affect microbial activity in the release of greenhouse gases back to the atmosphere. And it can also reflect how much energy is absorbed from the sun. So how much energy is absorbed or reflected back can actually heat up the surrounding atmosphere, which is sort of a feedback. And so, what were plants are, what they're doing, what they look like, is a really important component of understanding how the tundra will respond to changing environmental conditions.
MORGAN: To learn more about the unique plants found in the Arctic, the team turned to colleague Amy Breen, a vegetation ecologist with the University of Alaska Fairbanks.
JENNY: Amy’s expertise helped the team understand the six different plant communities that exist at the NGEE sites.
MORGAN: Plant communities are groupings of plant species that interact with each other, animal populations and the physical environment.
JENNY: In the Arctic tundra, these communities include herbaceous plants like shrubs and grasses, also known as graminoids.
AMY BREEN: These plant communities, and the species themselves, have the potential to respond differently to climate change. The plant community itself, if we take an approach where we look at it as being static, in which the plant community species assemblage doesn't change, there's potential in a particular site, over time with warming that we have a succession pattern of what we would expect to come into an area with warming. So, for example, we might have more of a graminoid tundra, but with warming, shrubs would come into that into that plant community. And then it would be transitioned to a different plant community.
MORGAN: As the climate warms, the plant communities that exist today could be totally altered, which could have a ripple effect on the ecosystem.
JENNY: Because of that potential, knowing exactly which plants live in these communities is important for informing models to predict future outcomes.
MORGAN: That’s been one of the shortcomings for previous climate models. Arctic plant life is often over-simplified or not accounted for in models, which doesn’t give the most accurate picture of what’s actually happening in the ecosystem.
BREEN: It's really important just on the ground to have that information so that as we scale up, and then we use this ground data for the modeling work. It's important because those plant functional types have different physiology and different responses to what could happen in a warming climate, whether it be warmer and drier versus warmer and wetter, or just sort of what direction we go, there are plants and species and PFTs that favor particular climate warming scenarios.
JENNY: Now, let’s go underground to look at what’s happening with the roots of these plants. Which happens to be a favorite subject for Colleen Iversen.
IVERSEN: Why do I love roots? We don't have enough time to talk about that. [Laughs] I think I find roots to be fascinating because people don’t think about them because they’re out of sight out of mind. So one of the things that fascinates me about my job is that I get to make measurements using cameras or robot cameras or, you know, digging holes and filling them up again, and get to see things that not a lot of people get to see. The reason roots are important is because they're doing all of the work of resource acquisition for the plant. And so, they're getting water that the plant needs to survive. They're gathering nutrients like nitrogen and phosphorus. And so, they're just as important as leaves. Leaves are the sort of carbon gathering organ for the plant and roots are sort of their sister below ground, but they don't get as much attention.
MORGAN: Colleen and her colleagues use a range of techniques to collect samples and measurements of plants and roots. These range from simple shovels to sophisticated drones.
IVERSEN: And so, the measurements we make on the ground are digging in the soil, looking at the roots and the little bacteria and the root houses, measuring the leaves above ground, measuring how tall the plants are, measuring how much of the ground surface they cover on the hill slope. And then another cool thing that we have is we have a crew from Brookhaven National Laboratory who uses un-crewed aerial vehicles to take pictures of the landscape. And so with these pictures, they can say, okay, we can see these plants from the air, and they're here and here and here. And they can make maps. And then if we can understand the links between, say, the spectral signatures and those pictures, or kind of the morphology of those plants, we can maybe predict further than we could walk in a day, what plant communities are out there. And then using those maps, we can then extend that inference from satellites, right. So further than anyone could ever walk, we can understand where these plant communities are out on the landscape. And because we know the characteristics of those plants and the soils under them, that can help the model infer processes across a much broader landscape than I could ever carry my shovel to.
JENNY: While plants on the Arctic tundra are often small in stature, the portion you see above ground is just the tip of the iceberg.
IVERSEN: I think one of the coolest things that we've discovered about roots in the Arctic tundra is that because it's such a harsh environment, plants tend to allocate or put a lot of their extra carbon below ground to make roots rather than stems or rather than a lot of leaves. And so, as we walk out across this boardwalk in Utqiagvik, Alaska, and look at out across the plants hugging the ground surface, if you were to dig up those plants, you'd see there's five times as much roots below ground as leaves above ground in some cases. They're investing there for the next year, or investing there to capture nutrients that are in short supply in a really cold, slow to decompose place like the Arctic tundra. And part of the reason that's important is because not just the resource acquisition, but because that's the way the carbon gets below ground. We know that soils store a lot of carbon -- twice as much carbon as the atmosphere if you average it across the world. And so how much carbon stays in the soils or how much is released as it’s decomposed by microbes and released as carbon dioxide or methane, is something that we think about a lot. I mean, that’s climate change, right? How much greenhouse gases are going into and staying in the atmosphere.
JENNY: As the permafrost thaws, so do the microbes frozen within. And this could potentially set off a feeding frenzy that releases tons of greenhouse gases into the atmosphere.
MORGAN: David Graham is a microbiologist at ORNL and member of the NGEE team. We talked with him to learn more about how something so small can have such a huge impact on a global scale.
DAVID GRAHAM: In the climate change realm, microbes are key to all kinds of biogeochemical transformations, all of the carbon cycling that happens once plants produce biomass, and that turns into litter. The microbes are really the catalysts, the change agents, of converting all of that organic matter back into nutrients or into carbon dioxide, into methane. They're really nature's recyclers. And that's critical for the way the planet functions but it also poses some interesting problems for greenhouse gas budgets when long frozen carbon, like the carbon that's stored in soils and permafrost, suddenly becomes available to microbes to degrade. And I like to describe this as imagining your freezer fails due to a power outage, it’s okay the first day, but after a couple days, when those peas that have been in the back of the freezer for ages suddenly start to thaw, and microbes and fungi start growing on them. They'll break down pretty quickly and no longer be recognizable vegetables, but they'll be recycling some of those nutrients, releasing a lot of carbon, and potentially methane, depending on the conditions that the thaw's happening.
JENNY: Thawing permafrost isn’t a novel concept in the Arctic. Some ground thaw happens every year in the warmer months, and then it refreezes once it’s colder. However, with warming temperatures, some of these thaw periods could last longer, and that could be a problem.
GRAHAM: The thaw season is longer. If you have an extra week until the ground freezes, that means it could be an extra week that those methanogens are living and an extra week in which they're making methane gas and dividing and increasing their biomass. So, we could see some very unexpected effects just by prolonging the freeze-up by a week.
MORGAN: Like his colleagues, Graham’s work begins in the field, collecting gas, water and soil samples and measurements to help understand and describe these complex processes. He then conducts research in the lab to further analyze the microbes.
GRAHAM: We also do a lot of laboratory-based experiments where we'll use some of the samples that we brought back, and we will incubate them, or we will perturb them or make other changes to the system so that we can measure how they respond. And in the laboratory, we have a lot of control over things, we can change the temperature, we can change the humidity or the water content, and then we can measure how the microorganisms are responding. And that gives us some ideas of the processes and how those processes are going to be influenced by change at a large scale in the future.
JENNY: As we’ve mentioned, all of the data gathered from the field work helps to inform computer models.
MORGAN: But don’t think the modelers have an easy job. The NGEE project takes modelers out of the confines of their comfy offices.
IVERSEN: We like to bring a modeler to the field so a lot of the trips that we have we will bring mathematical models with us so they can see the landscape that they're supposed to be representing in sort of virtual space. And also, I always enjoy sort of introducing them to the tundra for the first time. And it's really nice to see them, kind of get out there and love it as much as we do, the sort of the joy of digging a hole and discovering something that you didn't expect, is really fun.
JENNY: One of those modelers is Peter Thornton. He’s a section head for earth system sciences within the Environmental Sciences Division.
PETER THORNTON: It is, by far my favorite part of this project is that close coordination with the experimentalists, the observationalists and the modelers. I feel like the modelers get the better part of it. Because, you know, otherwise we'd be stuck behind a computer screen in our offices, but instead, we get to go out and really experience the ecosystem. It goes back to this abstraction concept that, it's just not possible to know what you're leaving out and to know where to begin with that process of simplification if you don't really understand what it is that you're looking at to begin with, what you're trying to predict.
MORGAN: And as an avid outdoorsman, Thornton doesn’t mind being put to work in the field.
THORNTON: It's so satisfying. You're actually down on your belly, on the tundra, the plants are only 50 centimeters tall or so and, and just, you know, digging into the soil with your hands and finding these roots and following them out. It's just so, I really love that being that close to the work. And then of course finding one, and it's like gold.
JENNY: By spending time in the field, Peter gained a first-hand view of the complex processes that his modeling efforts attempt to describe.
MORGAN: NGEE focuses on developing earth system models, which look at the interactions among the atmosphere, oceans, land and humans to predict climate change.
JENNY: But the massive scale of this challenge means that modelers have to try and simplify things for the models to even work at all.
THORNTON: Abstraction and simplification are kind of the name of the game there. And the way that we try to manage that complexity is to at least understand what it is that we are abstracting. So we have to start with the very fine scale processes. We have to start with an understanding of how microbes work and how they interact with each other, how they interact with mineral surfaces in the soil at a microscopic scale, how they interact with plant roots at a slightly more macroscopic but still pretty tiny scale. And by understanding those processes, we can begin to say, OK, here is a simplification, or here is an abstraction, which captures some important aspect of that system. And we're always updating that and trying to pick the things that are the most important, the most influential for the problems that we're trying to solve: these long scale large, long term and large-scale climate prediction problems.
MORGAN: While no model can predict the future with 100 percent accuracy, this work is giving scientists a look at what is likely to happen if warming continues.
THORNTON: The motivation for the whole project, as laid out by the Department of Energy when they asked for the original proposal, was to develop an improved predictive understanding of Arctic tundra ecosystems. And the predictive part of that is the key word there. In order to have an understanding that allows us to make predictions into the future, under conditions of a changing climate, we really depend on having capable models and lots of different ways you could think about the modeling, but we look at it from a process-based modeling understanding. So instead of just a statistical sense of what we've seen in the past, and what that tells us about what we might see in the future, we're trying to really get at a mechanistic-based understanding, of understanding how that the different physical, biological and ecological components work together, so that we can then make predictions about how all those things might interact and how they might change in the future as the climate warms, and as patterns of precipitation and humidity all are changing at the same time.
JENNY: Whether you’re a climate modeler, a botanist or a soil scientist, doing field work in the Arctic makes for tons of interesting stories.
MORGAN: We asked David Graham to describe an average day working in Alaska.
GRAHAM: In the fall when we're going up there, the days, the amount of sunlight in Alaska is quite long out there. They of course, have days in the Arctic where the sun doesn't set in the summer. And so, it can be hard to get situated to that kind of thing. We’re typically going early in the morning. And they're packing up our trucks, loading all of the sampling equipment materials that we have for the day, reviewing some of the plans and the safety precautions, getting people in the right place, and making sure everybody's got their food for the day, water and other things, and then heading out on a drive. And our field sites right now on the Seward Peninsula are anywhere from about 45 minutes to two- or three-hours’ drive away so we have plenty of time to get to know each other on the drive there, the radio stations broadcast out of Nome drop off after about the first 20 minutes or so. And the radio stations are a lot of fun up there. They're very local, they celebrate all the birthdays and all of the events going on, on there as well as some good music but after about 20 minutes or so when the radio cuts out there. It's either story time or observing the great landscape.
JENNY: Some of those safety precautions include training for wildlife encounters, because when you’re working in the Arctic tundra, you can have some unexpected visitors. Here’s Stan Wullschleger again.
WULLSCHLEGER: Part of working in Alaska is dealing with the challenges of wildlife. And doing that on a daily basis. It is simply part of how we go about doing our research. We certainly want to be safe when we have encounters with polar bears, grizzly bears, moose, muskox, caribou, foxes, and even little voles that like to run along the trail in front of you. So, these are just all examples of encounters that we have to safeguard and understand as we go about our research and Alaska. None of this was part of what we originally thought would be challenges. But nonetheless, we have dealt with them. Thanks to a lot of good input from our colleagues at the University of Alaska in Fairbanks and others that have gone before us.
MORGAN: And while they haven’t had any extremely close encounters with polar bears or grizzly bears, they’ve had plenty of sightings – including one that Amy Breen will always remember.
AMY BREEN: We did have one. It wasn't an encounter, but there were some bears on a hillside and they were a distance away from us. But the plants were low enough that we could actually see the bears and one of the bears are standing up on its hind legs. And you could see - the grizzly bears often can be blonde -- but you could see like the blonde, white belly. I think there were five of us and one of the group looked up and said, “are those berry pickers?” because they saw the bear standing on its hind legs. So, she's like, “Are those berry pickers? Did you see another car?” Because we will park our car, and then we will walk at the field site. And we hadn't seen another car. And there was one other grizzly, I think it may have been a sow with a cub. And she was up, like sniffing because she probably saw us in the vicinity and was like, you know, what is that? And so, we're looking on the hillslope. And I'm like, I just don't see them, you know, where are the berry pickers. And then somebody got out their binoculars and looked a little bit closer. And then I got in a visual and realized it was a bear and not a person. It was directly where we were headed. And again, we had, we had a large distance, and we were looking out for bears, or in this case, what we thought were people for a moment. And it's just one of those like aspects that really brings us together because we have to be communicating, we have to be looking at our landscape. And in a different way than we might in other environments that don't have those potential threats.
MORGAN: Of course, not all of Alaska’s wildlife has kept its distance.
WULLSCHLEGER: We've certainly had a lot of interactions with animals and insects in the form of mosquitoes. Most people don't know that there are 21 or 23 species of mosquitoes, but I can identify all of them for you having spent 10 years in Alaska.
JENNY: The NGEE team has spent nearly a decade chronicling the effects of climate change in Arctic Alaska.
MORGAN: After witnessing these effects first-hand, David Graham and Stan Wullschleger shared how the experience has changed their own understanding of what climate change means.
GRAHAM: I'm a microbiologist and biochemist. I'm used to thinking about really small things that we can't see. And I’m comfortable with looking at values of gas levels, the change and other things in the air. But the amazing thing about the Alaskan ecosystems is that you can visualize climate change up there, the geophysical changes that happen when ice melts, and ground subsides. And parts of hill slopes fall away due to erosion or solifluction, there you can visualize a changing landscape in a short amount of time that we just can't around here. And so, to see the impact of what warming and thawing and subsidence are doing to a landscape in a really short amount of time is pretty awesome.
WULLSCHLEGER: So early in my career, I understood climate change to be one of warming, of changing precipitation, of ecosystems getting drier. And then all of the consequences that would come from that. Working in Alaska has not only strengthened that perspective, but it has sharpened it because of the fact that ecosystems like those in the Arctic tundra, are simply held together by ice. There is a tipping point that comes with the freezing point of water. And when we reach that tipping point, the Arctic begins to unravel. And at no time during my career did I appreciate the sensitivity of our natural resources to a change like global warming. So I think my experiences in Alaska have not only strengthened my understanding of global warming, climate change and the consequences to our natural resources. But it's also made it much more relevant to the topics that we're interested in. But then also the consequences to animal migration, food production, and the fact that climate change does actually impact people that live in the native communities in Alaska. And without this project, I would not have had that full understanding and that appreciation for our changing climate.
MORGAN: Thank you for listening to this episode of the Sound of Science.
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JENNY: Until next time!