Awesome Jobs: Meet Sue Natali, Arctic Ecologist

By Erin Biba

Sue Natali has dedicated her life to watching the Arctic melt before her eyes.

Sue Natali has dedicated her life to watching the Arctic melt before her eyes. As an ecologist and biochemist at Woods Hole Research Center she travels to some of the most remote locations on Earth to dig holes in the ground and measure the carbon that seeps out. What she learns helps us better understand why permafrost is essential to the health of the planet. She chatted with us about what it's like working in the frozen North, why an increase in fires is damaging the frozen landscape, and how to preserve moose meat (and soil samples) in an ice cave in Siberia.

Photo credit: John Schade

Why do we care about permafrost?

My research focuses on permafrost--how much carbon is in the permafrost, and what happens to it when it thaws. That's important because there's a lot of carbon stored in permafrost in the form of organic matter, leaves, microbes, dead and decaying material. When a leaf falls in a warm environment it decomposes right away and returns to air as carbon dioxide and methane. But because the Arctic is really cold, when the plant material falls most of it doesn't decompose. A lot sits there and builds up and builds up. Some gets frozen into permafrost.

It's really cool depending on how the permafrost forms you can find whole plant material. There's a tunnel near Fox, Alaska, just outside Fairbanks that was dug in the 1960s. When you walk through the tunnel -- it's in the side of cliff -- as you walk in you're getting deeper toward the back going back 40,000 years, walking backwards in time. You can see giant ice wedges, you can see animal bones, and plant material that's not decomposed because it's frozen.

Photo credit: John Schade

So the reason I focus on permafrost thaw is because of the global implications. It stores a lot of carbon. There's twice as much carbon stored in permafrost as in the atmosphere, and three times more than in the all the world's forest biomass. This carbon is protected now because it's frozen. But when it thaws it becomes available to microbes, which eat the organic matter, use it for energy, and release carbon dioxide and methane.

If soils are well-aerated, the organic matter is decomposed to carbon dioxide. When the ground is wet, methane and carbon dioxide are released. Methane is important because it's 30 times more powerful as a greenhouse gas than carbon dioxide on a 100-year time scale.

What exactly is permafrost?

Permafrost is ground that remains below zero degrees for two or more consecutive years. It can contain any material, it's not just the soil. The ice is a really important part of the permafrost. You can have different types of ice formation like thin layers or larger ice wedges. I mean large -- bigger than a room. The ice content is really important because when the ice in permafrost melts, it doesn't support the structure of the ground, and you have very large ground collapse. You can have places that are very dry before thaw, but then if the ground collapses those same places can become very wet. Other areas may be wet because permafrost restricts drainage, but when the permafrost thaws, the water table can become deeper or drain away, and as a result some areas will become drier.

Photo credit: John Schade

It changes the whole landscape. In southeast Alaska where I work the ecosystem is peat plateaus with organic-rich soil. It's an interesting place because parts of the landscape are raised up because there's permafrost underneath them. You have other parts that aren't underlain by permafrost, and they've collapsed down so they're wet. You can go from dry to wet patches of landscape over space and time, and that dynamic interacts with changes in climate. And on top of these changes in air temperature, fire frequency has been increasing across many areas of the Arctic.

If everything is wet, how can fire increase?

Fire is increasing because the Arctic is warming and the fuel is drying, and because of increases in lightning. The place I work in southwest Alaska is quite wet. It was surprising there would be fires. But in a year with very low snow cover and warm spring, this creates a system that's flammable.

Fire puts the permafrost at higher risk of thaw. First fire comes through and burns off the plants and organic soil. Then you have a dark surface, which absorbs heat and lowers the albedo and creating this warm surface. But fire also affects soil insulation--moss and soil organic matter are great insulators. The air temperature can get warm in the summer in the Arctic, but moss protects the permafrost from the warm temperature. When you remove it you get an increase in ground temperature. It can take years to recover.

So how do we study permafrost?

I drill a hole in the ground and pull it out and look at it. The only way to really see permafrost is to drill into the ground or go to an exposure. Scientists are working on developing remote sensing tools to detect permafrost depth from the surface. But to know how much carbon is in permafrost or to learn about it's ice structure, mostly we drill out a core and look at it. It's one of the most exciting things I do. Each time I collect a new permafrost sample, I learn something that I couldn't see from the surface. Sometimes I'm completely surprised at what I find. Being in a tundra landscape and finding a large branch. Or seeing shifts in vegetation from moss-dominated to grass-dominated. That tells you that this landscape has changed over time. Sometimes you get a core that's 80- 90-percent ice. If you drill into an ice wedge, it's beautiful.

Photo credit: Stan Stotnicki

You can also see cryoturbation -- mixing that happens as the ground freezes and re-thaws. Organic material that's deposited on the surface mixes deeper into the surface.

The only way to find out how much carbon is the permafrost is by collecting and analyzing a sample. But our current knowledge about how much carbon is in permafrost is somewhat limited because there are many places of the Arctic that have yet to be measured.

There's permafrost in other places not just the North. I focus on arctic permafrost because that's where much of the carbon is located. There are also regional and local concerns as a result of permafrost thaw -- changes in infrastructure as a result of thaw is an important issue for many arctic communities.

Where are you working in Alaska, specifically?

One project is in the Yukon Kuskokwim Delta, a large river delta located in southwest Alaska. The area where I work is an inactive delta, it's a little bit inland. There were fires in this region in 2015, and in previous decades. In that project we're looking at the effects of fire on how much carbon was burned off, and how the terrestrial and aquatic components of the ecosystem are linked. The first time I flew over the arctic I asked myself how I could call myself a terrestrial ecologist in the Arctic because it's very wet in most places I work. There is always a transfer of materials from soil to ponds and streams and lakes, and especially after a fire.

Sue with an ice core in the Yukon. Photo courtesy of Chris Linder Photography

I'm also working on The Polaris Project, where we bring undergrad students to the arctic. This year we flew students by float plane into a remote field site in the Yukon Kuskokwim Delta.

Photo credit: John Schade

What kind of equipment do you need to do this work?

I bring instrumentation for measuring carbon dioxide and methane, for drilling permafrost cores, for sampling vegetation, measuring ground temperature and collecting water samples. On this trip, the National Science Foundation logistics team is helping us with setting up the camp, which was a major project for such a large group in a remote setting. We had about 20 people on this trip, 13 students.

We have such a large group so we have assistance with that end. We're responsible for the field supplies and thinking through everything you would do in the field. I need the drill, the motor, probes for measuring ground thaw, sensors for measuring temperature. Field notebooks and pencils.

Photo credit: John Schade

What I will do sometimes, if it's some sampling is new, I go outside and try it here at Woods Hole. I'll do a test runs before we head to the field. Working in a remote location requires assuming things will break, we need spare parts, a soldering iron, and a generator to run it. There's a lot of "what ifs" to think about, so I don't get stuck out there without the needed equipment.

How do you pick a spot to study?

We were exploring this area with a colleague when the fire happened. We got a floatplane to look around the area. We flew over the fire and thought "this is a really neat system"--a place where we could address questions about fire, about permafrost, and about terrestrial-aquatic linkages. We put in a grant to NSF to get money to do research there. It's called a "rapid grant" -- we want to get in right away to see the immediate effects of the fire.

We also spend time looking at maps. We have a geospatial specialist that traveled to the field with us and provided us maps so we can identify interesting landscape features. When we originally went to this place there's many lakes and a lot of them are shallow. Logistics also sometimes guides the decision making. We had to float plane into the field sites, so we needed to make sure we located near a landable lake where we could also walk to an unburned area and a burned area.

What is it physically like working in these areas?

Photo credit: John Wood

It's not that easy walking across the tundra. It's spongy. It's like a bouncy house. And in some places the sedges form tussocks, which is a growth form where the plant forms a big mound. It's a great thing to trip on when you're carrying heavy equipment. And this location is a mix of wet and dry so if you don't look at a map before you go, well, last year we wanted to go in a certain direction and we couldn't cross. It was wet and too wide. You want to know where you're going before hand.

The landscape does change quite a bit. I remember we landed someplace where I only had knee boots one year, not waders, and it was a bad decision. And we landed there the next year and it was dry. It definitely does change seasonally and yearly. But over longer time periods this place can change because of permafrost thaw. You get yearly and seasonal fluctuations and then you get long-term changes. Changes in vegetation tells us about the past history of the place. In a place that's raised up higher or dryer, we can find permafrost that's all moss, and we can tell the area was previously wet and then permafrost formed and it got raised up.

What's the camp like?

In previous years, we had small camps, but this summer with our large group, NSF logistics team set up our camp, which included a large kitchen tent, a science tent, and a common room for meals and gathering space. We all slept in individual or shared tents. The bathroom is basically a bucket. In past trips, it was literally just a bucket, but this year, we actually had a seat and a structure for privacy. For me it is fine, but some people have a harder time getting used to it than others. A lot of these students haven't camped out much. As long as people can anticipate it and recognize everybody else is in the same position, it's OK. It's a bonding moment.

When I'm doing other projects I usually know my team. I choose my colleagues because of the science I do, but I also choose people I like to work with. I know what it's like spending a lot of time in the field. With this student group we don't know them. So everyone participates in a field safety weekend that gives them a chance to learn about the field conditions. It allows us to learn about each other, identify people's strengths and weaknesses, and to see the way that people respond to situations differently.

You've also been researching permafrost in Siberia. What are you looking at there?

There's a couple projects I'm working on. This area of the Arctic has trees growing on shallow permafrost, so we're looking at how fire affects forest density and how that impacts carbon in soils in permafrost.

The place where I work is in Northeast Siberia. There's a research station there and there are two families that have been running it for decades now. The permafrost here is made up of yedoma deposits, which contain a lot of Pleistocene-aged organic-rich material and often a lot of ice. This ancient carbon is important when we think about thaw because there is the potential for emissions of carbon that hasn't been cycling in our system for tens of thousands of years and now may be released into the atmosphere.

Photo credit: Stan Stotnicki

Thaw sometimes is top down: air warms, soils warms, things thaw from the top. But here and across the arctic there can be very large melting of ground ice, which can cause abrupt ground collapse. You now make tens of meters of ground open to the air. It's not top down any longer. Sometimes it's a hole or an exposure that thaws from the sides. That's one of the reasons there's a lot of focus on this area.

Who are the families running the research station?

They're a family of russian scientists. Sergey Zimov and his son Nikita are now are in large part running the station. They also have a place called Pleistocene Park, where they're studying how the presence of large herbivores may protect the permafrost. They're trying to recreate a Mammoth Steppe ecosystem, which is a type of grassland.

They're bringing in moose, muskox, caribou -- herbivores -- to test the hypotheses that this system, which used to be highly populated by animals, will store more carbon and protect permafrost when the animals are present. You can see how prevalent these large mammals were from the bones that you find in areas where permafrost is thawing. At some thawing exposures, you can just walk along and find Pleistocene animal bones. There's a lot of bones--a surprising number. The hypothesis is that conversion to Mammoth Steppe will protect permafrost because grasslands absorb less energy than dark trees and shrubs, and the animals, by trampling the snow, reduce the snow insulation and and keep the soils colder in winter.

They're pretty interesting. They just used crowdsourcing for funding to really populate the park with animals. It's harder to keep a fence up in northern siberia then other areas.

So we stay at the Northeast Science Station research center. When the Polaris Project group traveled to Russia, we lived on barge at the station, or one summer we took the barge down river close to the Arctic Ocean and beached it and lived on the barge while we conducted research.

Photo credit: John Schade

The barge has rooms built on top of it. There's bunks inside, four people per room. There's a kitchen area, a porch and it has a sauna. Russians like their saunas. We also packed all of our research supplies onto the barge. At the research center there's labs and instrumentation. But on the barge you have to pack everything. We also brought a mini-barge that functioned as housing and lab space. We were doing soil incubation experiments in there, where you put soil samples in a jar and expose them to different temperatures and measure the gasses that come out.

Camped out at this location, we felt like we were in the middle of nowhere but there's a lot of old Soviet-era equipment and infrastructure lying around. There was an old road nearby. We were on the Kolyma River, an area where there had been a lot of labor camps. There are some remnants.

What is a typical session of sampling like?

It depends on what I'm doing, like if I want to know how much carbon dioxide is coming out of an ecosystem I bring equipment to measure gas fluxes. Working in the tundra, the vegetation is very short, often below my knee. I can take a plexiglass chamber, put it over the ground, and capture the air. Tubing comes from the chamber, and fans pump the air into a CO2 analyser. Sometimes I want to know how the carbon dioxide concentration changes over time. If it's daylight it will probably go down because the plants are taking up carbon dioxide. If I put a cover over the chamber and mimic nighttime I'm just getting respiration from plants and microbes so I'll see carbon go up.

Photo credit: John Schade

If I'm working longer term, over weeks, I'll set up bases and keep coming back over time to measure gas fluxes. I also often want to characterize the ecosystem: what's the vegetation composition, depth of organic layer of the soil, and depth of thawed ground. I will lay out transects. I take a long tape and measure vegetation composition every meter along the tape. I measure thaw depth from the top of the ground to where the ground is frozen, basically by sticking a metal pole into the ground. All of these measurements tell us something about what controls carbon cycling in arctic ecosystems. I want to figure out what's going to happen when the ground thaws and what are the important components of this landscape that control carbon fluxes.

If I can relate a flux rate to a temperature and a thaw depth and vegetation type I can then scale that up to the larger area. I work at a discrete locations, but the goal isn't to just find out about that plot, it's to use that information to learn something larger about the landscape.

What's it like working in Russia? Are there challenges? Our two countries aren't exactly friendly.

The Russian scientists that I work with are great colleagues and they facilitate our access to research areas--by helping to get permission to work in the region and to access remote field sites. Most of the permafrost region is in Russia. While it can be a challenge logistically to work there, once you're there the science opportunities are worth the challenges.

The biggest challenges are bringing equipment and data in and out. Especially bringing out samples and equipment.

Photo credit: John Schade

I have frozen permafrost samples currently sitting in an ice cave in Siberia and I'm trying hard to get them back.

Science is currently under threat in our country, especially science that focuses on climate change. Do you have any suggestions for how folks can help support and bolster research?

One thing everyone can do is contact their elected officials by writing a letter and picking up the phone. Tell them that climate science is important to them. In any political environment policy makers have a lot of decisions to make. Unless they hear that science and limiting climate change is important they may not make that decision.

People can also volunteer and reach out to scientists. Here at Woods Hole Research Center I'm happy if somebody wanted to volunteer to be part of the project of my projects.

And also just talking to other people about science and the relevance of science is important. We don't always have these conversations about science, and I think people are really influenced by the opinions of their neighbors and family and peers. If someone you know personally talks about work that is interesting and important for protecting the climate, that can have a big impact.

Not all science is done in a lab by guys in white coats staring into microscopes. Lots of discoveries require brave men and women to put their boots on the ground and get down and dirty in dangerous environments. We profile one of these field scientists, tell you how they do their job, and explain the science behind what they do. If there's a scientist or field of science you're dying to hear more about shoot us an email or a tweet: erin at erinbiba dot com, @erinbiba