Sarah Ludwig fell in love with the Arctic as a teenager. Now in her research, she is measuring how permafrost, an integral part of that ecosystem, is beginning to thaw, which would have serious consequences not only for the Arctic and the people who live there but on the entire planet.
Ludwig is a biogeochemist with the Woods Hole Research Center, studying how nutrients like carbon, nitrogen and phosphorous move throughout tundra ecosystems. Her work has taken her to remote places in Alaska and Siberia to measure how a warming planet is affecting permafrost, the layer of frozen ground found around the Earth’s poles. Historically, the permafrost has been a carbon sink, freezing organic matter and keeping it from decomposing. However, scientists have recently found that the permafrost is beginning to thaw, with the potential to release billions of tons of carbon dioxide into the atmosphere.
“When you talk about permafrost, we always say its thawing instead of melting.” Says Ludwig. “I like to think of how when you take chicken out of your freezer.”
I got the chance to speak with Ludwig about her research and the consequences of a thawed permafrost. Below is a transcript of our conversation edited for length and clarity.
Chris Anderson: Of all the things to research, you chose to literally go to the ends of the world and study permafrost. What made you get interested in that?
Sarah Ludwig:I grew up in Minnesota, and I spent my summers canoeing in Northern Minnesota and Canada. I was part of a YMCA program that sent kids further and further north each year and culminated in a 2-month long trip to Canadian Arctic when you were 18. I didn’t really know that much about science then, but I loved being in the Arctic and being outside.
When I went to college, I just enjoyed my environmental science classes. Then I found an undergraduate research experience with one of my professors to do permafrost research in Siberia on biogeochemistry and permafrost ecosystems for the summer. I learned that being outside is just as much fun as when I am doing science as it is when I am canoeing!
CA: What kind of science are you doing in the Arctic? Where are you doing it?
SL: I study carbon cycling, nitrogen cycling, and phosphorus cycling. I look at where these elements are in the ecosystem and how they move and change into different components. For carbon that might be measuring plant biomass or soil organic matter. We look how it’s being decomposed or if it’s becoming dissolved organic matter. We measure if the carbon is being transformed into gases like methane and carbon dioxide and being released into the atmosphere or if it’s being consumed by microbes in soils and sediments. It’s about following an element throughout its life in an ecosystem and I do this in permafrost ecosystems, mostly in Alaska and Siberia.
CA: Most folks haven’t had the opportunity like to you to get all the way up to some of the high latitudes close to the poles. If you aren’t familiar with the permafrost, what does it do in the ecosystem?
SL: The permafrost provides a lot of different services, both for Arctic ecosystems and for the world at large. Permafrost keeps things from decomposing, keeping nutrients, which are important for plant growth, locked away in the frozen ground instead of being recycled when they get decomposed. This allows organic matter to build up and stay preserved for thousands of years, storing massive amounts of carbon.
Permafrost also completely changes the hydrology, which is how and where the water moves in an ecosystem. Normally, water will infiltrate down quite deeply into the soil and make its way into an aquifer for example, or make its way down into a river or something like that. But in landscapes with permafrost, there might be frozen ground all the way up to the surface in the winter or the ground might be thawed only as much as half a meter deep at the most in the summer. So, water is going stay close to the surface, restricting its movement.
This is very important for the ecology of the area. If the permafrost thaws, it will affect the nutrient availability, which will not only have a huge impact on the plants and soil microbes but the rest of the ecosystem as well.
CA: How is this impacting the people who live there and how are they coping with the changes?
SL: The biggest factor that will affect people is the structural component of permafrost. If you have a house, or a road, or an airport runway on permafrost and then the permafrost thaws, whatever you are building is going to collapse. There are even instances where historic graveyards are collapsing into the ocean due to permafrost thaw.
Residents have had to build their homes on stilts because the heat of the building will start to thaw the ground beneath it. You must build all your pipelines above ground, which makes having running water difficult. Fairbanks, where I lived for several years, is on discontinuous permafrost, some people live on permafrost and some people don’t. Some people can sink a well through the permafrost to get running water, while some people live without running water. The largest city that exists on continuous permafrost Yakutsk, Russia and that’s a few hundred thousand people, with skyscrapers even, all built on permafrost. Permafrost thaw is going to affect the lives of a lot of people.
Sometimes it can be hard to see climate change happening. Even with all the extreme weather events we’ve had this year, there are still people who will argue that the climate is not changing. But in the Arctic, it’s just obvious, you don’t have to be a scientist to realize that. It doesn’t matter what people’s backgrounds are up north, people accept climate change because they see it happening in front of them. They see it in changes in weather, changes in snowpack, changes in the length of the growing season, and it’s because the Arctic is warming at an accelerated rate relative to the rest of the world. They have already seen major changes and they are going to continue to see them faster.
CA: What about for people who don’t live in the Arctic?
SL: For the rest of us who don’t live year-round on places with permafrost, the biggest service that permafrost provides is carbon storage. Permafrost is hundreds of meters deep in many places. That’s a lot of soil and because it’s not decomposing, that’s a lot of organic matter. There’s twice as much carbon in the permafrost as there is in the entire atmosphere right now.
CA: Wow! That’s got to be carbon stored form living things from thousands, maybe millions of years!
SL: Oh, thousands definitely! The most carbon-rich permafrost is called yedoma, which is from the Pleistocene Era. Remember, the permafrost is providing a service for the entire planet by storing carbon dioxide and keeping it out of the atmosphere. If we thaw permafrost, we are going to reverse that and there’s not a great way to prevent that from happening. Now that’s not all going to thaw at once, and all that does thaw isn’t going to be decomposed at once, but it was a huge carbon sink and a lot of it will go into the atmosphere.
CA: You are on the front lines, making direct observations of the permafrost thawing. What’s have you seen on your research trips?
SL: Permafrost thaw is already happening in a lot of places. There’s quite a large area of permafrost that is right around 0°C (32°F), so it’s still frozen, but it won’t take much warming to thaw. There’s other permafrost that is -5° C (-23°F), so it only has to warm up a little bit more before it becomes vulnerable to thawing.
A lot of what we are trying to figure out where permafrost is vulnerable, how much carbon is in that permafrost, how much ice is in that permafrost, the amount of ice that is relative to soil or rock or other things will affect how it will collapse when it thaws.
CA: How do you measure how much carbon is being released from permafrost areas? What are you guys seeing with that?
SL: We try to have a landscape approach to the puzzle of carbon cycling. When we are in the field, we measure how much and what form of carbon is in streams, lakes, and soils. We then drill cores in the permafrost and take them back to the lab and measure how much carbon, what form it’s in and at what depths.
What we have seen in that there are huge amounts of carbon being released into the atmosphere. There’s a lot more carbon buried at depth than we expected. A lot of that is because these are hard measurements to get, so a lot our estimates aren’t from as many data points as we would like.
CA: Have you found that the level of atmospheric carbon above the permafrost is higher compared to other parts of the globe?
SL: We don’t have the instrumentation to measure that. You would need a pretty intense weather station to make a regional carbon dioxide measurement and we are working in places where we are camping with generator-powered equipment for the summers. But if you know where carbon is moving throughout the ecosystem, you can measure the change of carbon in the ground and estimate how much has been released into the atmosphere.
CA: As you are collecting data on ground that is literally falling out from underneath you and others, what is the scariest part of this? What do you think the most serious consequences are, not just for people who live the Arctic, but for all of us?
SL: I think the most serious part of this is not the part that I do any work on. The immediate human impacts are by far the most serious. People who live on permafrost are already struggling to deal with those changes and that’s something we don’t have a way to address as a society yet. There’s no rainy-day fund for that kind of disaster.
But for the consequences of carbon cycling, we might not be able to do anything in the Arctic to change that. We have some collaborators in Russia working on an experiment going called Pleistocene Park, trying to return the tundra to the mammoth steppe ecosystem, which was much more productive. The idea is in a mammoth steppe ecosystem you have grassland instead of tundra, so you are storing a lot more carbon, grasses are more productive and have deeper roots. You also have a large number of herbivores trampling the snowpack, which increases the winter cooling factors, which allows for permafrost to accumulates faster because your wintertime soil temperatures are colder. Ideally, this is a negative feedback to the carbon cycle, reestablishing a carbon-rich permafrost. But that’s not exactly applicable on a large scale.
CA: It sounds like this is an accelerating problem. Is there anything that anyone can do to help permafrost ecosystems?
SL: You don’t have to go the Arctic to be able to make a difference. Take climate change seriously and make sure the people who are making decisions about our policies are also taking this seriously. We might be seeing a bad situation in the Arctic right now, but it’s going to be rough in lots of places around the US eventually.
There are steps forward out there but it’s going to take a concerted effort to be better at managing our carbon outputs. Right now, our policies don’t consider things like permafrost. We are planning on reducing our anthropogenic outputs a certain amount to decrease global warming by a certain threshold, but we aren’t accounting or the fact that outputs are being matched by potential permafrost thaw. That’s going to make us overshoot the thresholds. We need to be even better at reducing our emissions to account for all the natural changes that will happen with climate change.