March 22, 2021

What Tree Rings Can Tell Us About the U.S. Civil War

Posted by Shane Hanlon

Max Torbenson coring a bristlecone pine in central Colorado. Photo by Daniel Griffin.

Many of us know that tree rings can tell us how old a tree is. But there’s so much more we can learn from these seemingly simple lines.

 In the mid 1800’s, right before the start of the U.S. Civil War, North America began to experience unusually low rainfall that lasted approximately 10 years. This drought, on par with the Dust Bowl of the 1930’s, may have played a role in the near extinction of the American Bison due to the migration of people to areas that were lusher and more conducive to farming.

Max Torbenson, a postdoc at The Ohio State University in their Civil Engineering Department, studies tree rings to learn about past environments and climates. While he admits that it’s difficult to attribute the effects of the drought to altering any specific part of the Civil Wars, reports do describe issues in supply chains due to rivers drying up and shortages of water for troops and animals used for transportation.   

In the latest episode of AGU’s podcast Third Pod from the Sun, Max describes how the work he and others are doing can inform us about how climate change has been influencing wildlife and humans for hundreds of years. Listen as Max recounts his journey as a scientist, takes us to remote field locations full of danger, and fills us in on why he fell in love with U.S.  

This episode was produced and mixed by Shane M Hanlon (@EcologyOfShane).


Shane Hanlon:              Hi, Nancy.

Nancy Bompey:             Hi, Shane.

Shane Hanlon:              It’s been a while since we’ve done this.

Nancy Bompey:             I know. It has been a while. How are you doing?

Shane Hanlon:              Good. It’s good to see you. We live kind of close to each other, but winter is kind of rough seeing folks, especially now. Well, so we’re coming back today with an episode about… Let me just ask you. So, what’s one of your favorite things to do, Nancy? What’s one of your favorite hobbies?

Nancy Bompey:             You know, reading.

Shane Hanlon:              You love to read. I think in one of our previous episodes, you said that [00:00:30] you’d want a book on an island if that’s the only thing you could take with you or a library somehow. What’s some of your favorite genres to read? What kind of stuff do you like?

Nancy Bompey:             I mean, I’d love just general fiction. I really like historical fiction.

Shane Hanlon:              Define historical fiction.

Nancy Bompey:             Well, it’s like something that happens in history, but it’s a fictionalized account. It’s made-up people usually, or it could be a real person but they make up what happened to them [00:01:00] because the evidence is sparse, but it takes place around something that really happened like a war. There’s a lot of that like World War II stuff. Anything, really.

Shane Hanlon:              Have you ever gotten into the Civil War stuff?

Nancy Bompey:             A little bit. I’m not a huge civil war buff, but around here there’s a lot of civil war stuff around our area.

Shane Hanlon:              Yeah, I know. We live in Virginia. Well, lucky for you, we’re going to be talking [00:01:30] about a little bit of that today.

Nancy Bompey:             Oh, great. Maybe I’ll learn something.

Shane Hanlon:              Welcome to the American Geophysical Union’s podcast about the scientists and the methods behind the science. These are the stories you won’t read in a manuscript or hear in a lecture. I’m Shane Hanlon and I’m Nancy Bompey.

Shane Hanlon:              And this is the Third Pod from the Sun. So Nancy, it’s lovely to catch up with you even if it is virtually and we could just see each other outside by walking 20 minutes. [00:02:00] But the reason why I asked you specifically about your hobbies and, I guess, historical fiction which I’m interested to learn more about, is that we talked with someone for today’s interview who is a scientist, but has a connection to the Civil War.

Max Torbenson:            So my name is Max Torbenson. I’m a postdoc at the Ohio State University [00:02:30] in the Civil Engineering Department. And my background is quite diverse. I have a PhD in Geosciences, a master’s in Geography, and an undergraduate in Archaeology. And I guess what ties all those things together is tree rings. So we’re using tree rings to study past environments and climates. So that’s how [00:03:00] I try to sell that all these things are connected.

Shane Hanlon:              How did you make the transition from your PhD in more geospace area to civil engineering? you said, tree rings, but what is that connection?

Max Torbenson:            At Ohio State, there’s a big focus on water management. S o everything from bridges, building bridges to looking at flood and drought. [00:03:30] And one of the things that tree rings can do is to reconstruct climate and in this case, streamflow back in time. So my adviser there was looking for someone with the skillsets, paleo-climatic reconstruction.

Shane Hanlon:              This sounds like a perfect fit for what Max would be doing and the kind of project that his advisor put him on.

Max Torbenson:            [00:04:00] Starting around 1855, slightly before the US civil war, especially the central us but probably the continent as a whole, experienced unusually low rainfall. So from 1855, 1856 for another 10 years or so, there was persistent drought across North America, [00:04:30] but especially in the central part. So Northern Texas, Oklahoma, Kansas. We know this from historical accounts. We know this from tree ring studies and from climate model simulation. And this drought was on par perhaps even worse in places than the Dust Bowl drought of the 1930s. And it’s thought, for example, that played a role in the near [00:05:00] extinction of the American bison. So people moved into the plains around this time and the grazing animals were kind of pushed aside from the good spots or the good grass. And then on top of that was a big drought. So it’s thought to have played a significant role in that.

Shane Hanlon:              [00:05:30] So it’s a civil war drought more because of the timing in that time, did it have, or do we even have an inkling of whether or not this is true? Did it have an effect on the civil war itself? Like where troops were, how they advanced, how they were affected and how that might’ve actually altered the course of the war and how, and like the history behind it.

Max Torbenson:            So that’s always kind of iffy here almost bordering on [00:06:00] environmental determinism, right when you’re trying to, but there were definitely years during the war that were dry and there’re historical accounts of Tennessee, where some of the troops couldn’t get supplies because they transported down river so long. But I think the effect or [00:06:30] the drought itself was most severe in the central USO and the war, or, you know, in the 1862, 1863 was the big battles. And we’re mainly in Eastern United States. So the kind of trans Mississippi theater of the war, there were battles in Oklahoma and Arkansas that’s probably, if it had an impact, [00:07:00] that would be where that impact.

Shane Hanlon:              So, maybe, but since the war was concurring and I’m in DC area, so like my part of the country, more so less effect of the drought there than where it was really hitting hard.

Max Torbenson:            Yeah. That would be my end. And again, it’s likely that it had some effect, but because again, this was [00:07:30] the driest decade that we know of in Texas, Oklahoma, Kansas, and Arkansas so it’s likely that it had some effect, but probably I wouldn’t go as far as say that had an impact on the outcome.

Shane Hanlon:              Gotcha. How so you said, we know from like different accounts of, like from folks that this happened, what, who was recording at the time, are these just like [00:08:00] first person narratives of just people lived in the areas where these, where they like white people, where they native Americans, like who, what types of groups were recording these things?

Max Torbenson:            There is a wealth of information and including actual historical, what we now call instrumental data. So in the kind of frontiers, there were forts that [00:08:30] were stationing soldiers and they had some sort of, or they had instrumentation or measured how much rain fell. Carrie mock climate historian has done work in the central youth on this, but we also have newspaper accounts. We have some of the native american tribes in the great Plains used pictograms. So [00:09:00] painting, paint. Yeah, exactly. And different symbols meant different things. And there have been interpretations suggesting that for example, 1855 snow and as the sitting summer, and that has been interpreted in combination with other records serve in a very dry year.

Shane Hanlon:              Okay. So everyone was documenting it both from [00:09:30] a scientific perspective, basically it was affecting everyone and there’s a good record of it.

Max Torbenson:            Yeah, definitely. And, and again, this is time in that part of the continent where European immigrants were just starting to, so the 1850s is kind of where we’re starting to see expansion westwards and there. So, and that, again, [00:10:00] in combination with a drought is thought of played a role in how local wildlife, including the bison and was able to get on. I think the results suggest that places outside of this core region, they have experienced kind of waxing and waning influence events. So on local drought. So places like Arizona, Southern California, Eastern Texas, so for certain [00:10:30] periods, and so place an important role on drought probability while for other periods, or it’s not much of a relationship at all. And what that also means is that those changes that we’ve seen and the instrumental data for the 20th and 21st centuries, those types of changes appeared up in a somewhat stable feature of climate dynamics in the past 350 years.

Max Torbenson:            And in terms of the civil war drought. So the civil war [00:11:00] drought occurred during persistent Lanea conditions. It doesn’t necessarily mean that end, so cost the drought while it probably did to a certain degree, but it definitely played a role in the intensity and persistence and also spatial imprint. So the fact that for those 10 years, so 1855 to 64, a lot of the US, the continental us [00:11:30] was in drought conditions of various magnitude. The kind of final thing there is that these expansions and contractions [inaudible 00:11:42] influence, especially into the great Plains, which was where the civil war drought really hit the hardest. We speculate that those expansions and contractions could be tied to conditions in the Atlantic ocean,

Shane Hanlon:              The [00:12:00] sites you’re on, are they public lands? Are they private sites? What type of permissions do you need to get to do this type of work?

Max Torbenson:            They can be all sorts. And I’ve been very fortunate, especially during my PhD to travel and work and all over the U S and Mexico and Brazil and South America. So it kind of depends on where you are. And again, if you’re on public land, you usually need [00:12:30] permission from, let’s say it’s a national park or a state park, or, and there are private land owners that are really interested in knowing the history of their own land and understanding their surroundings better. So usually that’s not a problem. And of course, some of these sites are more remote than others. [00:13:00] I’ve definitely had people come up to me asking me what I’m doing and why I’m hurting the tree.

Shane Hanlon:              Do you, have you had any especially antagonistic interactions with folks?

Max Torbenson:            No, I can’t say to be honest, most people have been very good and interested. I think most people are interested in this. [00:13:30] I’ve heard stories and there are obviously you always want to get permission before. And sometimes that might actually be tougher sometimes to get the permission to core because a, they can be in places where wildlife tends to be connected where they don’t really want any [00:14:00] easier disturbance or so

Shane Hanlon:              I was interested in the interactions he had with people because sometimes he was on private land sometimes on public land, but also he’s on the field and some really interesting locations and had some, let’s say unsavory interactions with some wildlife

Max Torbenson:            Looking back at the field. I always want to go back. But then obviously when you’re there, especially early, when I started, [00:14:30] I, you think that you can do more than you actually can. Right. I, I had a, a spider pretty bad spider bite and out in Oregon when I just, when I just moved to the U S and I was kind of new and I also had some sort of, I don’t, I still don’t know what it was, but there was either a bite or a reaction to something in [00:15:00] the Amazon where I had something, a red Hatter and a started creeping up my arm that looked like along my veins, which was, yeah.

Shane Hanlon:              Did you have to go to like the hospital? Or I guess if you’re in the Amazon, I don’t know if you have that available, but

Max Torbenson:            We had gone back to civilization sort of say when this started happening, but [00:15:30] I was young and dumb and fortunately nothing really came of it, but the pictures look kind of grim now in hindsight.

Nancy Bompey:             So it sounds like he’s been all over the world doing this kind of work, which is super cool. And then I guess wound up in the States.

Shane Hanlon:              So you touched on this, but so you are, you’re not from the States.

Max Torbenson:            Yeah. I’m from Sweden originally. So

Shane Hanlon:              What, what drew you here? Was [00:16:00] it the work specifically, you were doing your lab? Was it something else? What really got your interest? Not only in the States, but specifically this type of work that you ended up doing?

Max Torbenson:            My undergraduate degree was in archeology and so slightly different. And there people use tree rings to date artifacts or date buildings, or, and I fell in love with tree rings during my undergraduate. And [00:16:30] I realized that a, I wanted to do continue to study, but I wanted to do it in a English speaking country, because a lot of European countries where tree rings are used are it’s either Germany or Switzerland or Spain.

Max Torbenson:            And I got an offer to do a masters at the university [00:17:00] of Minnesota. It’s been a journey, right. I think, I think I’ve been, again fortunate. Everyone’s been so nice. And we, I consider Arkansas probably more home than anywhere else right now. It w it was a bit of a change moving to the U S and I think that first step is probably the toughest, right? Sometimes you kind of just have to do it, [00:17:30] but of course there are cultural differences than I keep seeing them, but overall, and what really strikes me when, when people ask me why I like, why I love the U S is that it’s diverse from, especially from my point from an environmental standpoint, you can be in Arkansas and look at posts and bald [00:18:00] Cypress trees that are a thousand year old.

Max Torbenson:            And you can, if you don’t like that, you can go to California and be up in the mountains. Bristlecone pine, the redwoods and Oaks up in Minnesota, or, you know, wherever you have everything.

Shane Hanlon:              Talking with max really made me kind of appreciate, not necessarily just nature, but I guess trees, I’m [00:18:30] a more of an animal guy. And so I never really thought about, I don’t constantly think about trees a lot and how important they might be.

Nancy Bompey:             They’re really important. And like we said, we were chatting a little bit before about, being outside in the quarantine. And that’s kind of the things that you can do is be out in the woods. And there’s something so awesome about being among the trees being among the woods and that, we have so many different kinds of trees here, which is really cool. And you start to notice that all of that a lot more, I think when you’re really, [00:19:00] it’s the highlight of your day sometimes.

Shane Hanlon:              Yeah. Yeah. And it’s, it’s not Arkansas, but I, you and I both live in Virginia and I really appreciate what we have here as well. So really, really fortunate to, to be able to experience that. All right, folks. Well, that’s all from third pod from the sun.

Nancy Bompey:             Thanks so much to Shane for bringing us this story and to max for sharing his work with

Shane Hanlon:              This podcast was produced and mixed by me.

Nancy Bompey:             We’d love to hear your thoughts, please rate and review us, and you can find new episodes [00:19:30] wherever you get your podcasts, or [email protected]

Max Torbenson:            Thanks all. And we’ll see you next time.