Radiolab - The Fellowship of the Tree Rings

Episode Date: July 14, 2023

At a tree ring conference in the relatively treeless city of Tucson, Arizona, three scientists walk into a bar. The trio gets to talking, trying to explain a mysterious set of core samples from the Florida Keys. At some point, they come up with a harebrained idea: put the tree rings next to a seemingly unrelated dataset. Once they do, they notice something that no one has ever noticed before, a force of nature that helped shape modern human history and that is eerily similar to what’s happening on our planet right now. With help from pirates, astronomers and an 80-year-old bartender, this episode will change the way you look at the sun. (Warning: Do not look at the sun.)  Special thanks to Scott St George, Nathaniel Millett, Michael Charles Stambaugh, Justin Maxwell, Clay Tucker, Willem Klooster, Kevin Anchukaitis EPISODE CREDITS Reported by - Latif Nasserwith help from - Ekedi Fausther-Keeys and Maria Paz GutierrezProduced by - Maria Paz Gutierrez and Pat Walterswith help from - Ekedi Fausther-Keeys and Sachi MulkeyMixed by - Jeremy Bloomwith mixing help from - Arianne WackFact-checking by - Natalie Middletonand Edited by  - Pat Walters CITATIONS: Books:  Tree Story (https://zpr.io/ULX279uzgW9q) by Valerie TrouetSweetness and Power (https://zpr.io/cUEGqGGWMSaQ) by Sidney Mintz Our newsletter comes out every Wednesday. It includes short essays, recommendations, and details about other ways to interact with the show. Sign up (https://radiolab.org/newsletter)! Radiolab is supported by listeners like you. Support Radiolab by becoming a member of The Lab (https://members.radiolab.org/) today. Follow our show on Instagram, Twitter and Facebook @radiolab, and share your thoughts with us by emailing [e-mail].   Leadership support for Radiolab’s science programming is provided by the Gordon and Betty Moore Foundation, Science Sandbox, a Simons Foundation Initiative, and the John Templeton Foundation. Foundational support for Radiolab was provided by the Alfred P. Sloan Foundation.

Okay, wait, you're listening. Okay. Listening to radio lab. Radio from WNYC. Okay, I'm just going to start. Tree walks into a bar. Okay, bartender asks, what do you have? Tree says, yeah, are you on a guess?

Well, no, I'm just, I'm already, I'm already dismayed by your concept, because trees, as I last check, can't walk, they're rooted to the ground. They just go with it. Lulu, just go with it. Come on. Okay, tree walks into a bar. Okay. Yeah, bartender says, what do you have?

Come on, okay, tree walks into a bar. Okay, yeah. Bar tender says, what do you have? I've got a branching decision ahead of me, but I'll go with a logger. Anything but a logger. Oh, anything but a logger. Okay. That's right. That's right.

Another one. Okay. Three dendro chronologists walk into a bar. And... Okay, wait. Yeah. Dendro chronologists are people who look at dendrads in your brain. No, there are people who study tree rings.

Oh, they just look at the rings inside a tree stump. That's what they do. That's what they study. Okay, so three dendro chronologists walk into a bar and... I mean, that's not a joke. Okay, so three dendro chronologists walk into a bar. And? I mean, that's not a joke, that's the beginning of the story. Okay. The rest of the story is basically

three tree ring scientists walk into a bar and as the night goes on and as the talk gets a little boozeer, they come up with this kind of hair-brained idea to take this one particular set of tree rings To put it next to a seemingly unrelated thing But in doing that they start to see All kinds of new things that they've never seen before that maybe nobody has ever seen before including an invisible hand

shaping the history of our planet and the history of us. All right, well before we take off on this wild tale, should we do the who we are? I'm Lathif Nasser. I'm Lila Miller. This, of course, is radio lab. All right, so set it up for us. Where did it all start? Okay, so we're in Tucson, Arizona, at a bar called Tigers Taprim. Okay. It's more than a hundred years old,

and it's sort of famous locally for its very old bartender who has been serving drinks there since 1959. Cool. All right, now I'm picturing Gandalf, like serving drinks to these three tree rings scientists sitting there looking at the bar, in the rings on the bar. We're not freaks. We go to a bar, we go and drink, we don't count rings.

This is Valerie. Valerie Truet. Scientists number one. And I'm professor of dendrochronology at the University of Arizona. Which is in Tucson. Where you would not necessarily expect a tree ring laugh because there's not many trees around. But kind of weirdly, she says this is actually where the modern field was born.

Because the first dendrochronologist was actually an astronomer who was studying the sun. And relic a Douglas. That happened because... He thought to himself, well, trees, they're sensitive to the sun. You know, they eat sunshine. And they get to be very old,

so maybe I can learn something about the sun from You know, they eat sunshine. And they get to be very old. So maybe I can learn something about the sun from the rings and trees. Like trees are the original astronomers recording their solar observations. Yeah, exactly. But what could you actually learn about the sun from the rings? Isn't it just like each year the tree grows, it gets a ring and you learn how old it is by counting them. Like, is there a thing beyond accounting the ring? Yes, so it's a very good question. So Valorie explained, yes, it's true. Most trees grow a new ring every year.

But what fewer people know is that not every ring is equally wide, not every ring is equally dense, not every ring has the same chemistry. And it's in those differences, Valorie says, where you can learn all kinds of stuff about the tree and even stuff not about the tree. Exactly. So like what?

Like what? Well, you could learn about the weather. How hot or how cold it is. You can see how much it rains, or it didn't. You can see trauma, you know, which could create a very skinny ring. You can see fires, which leave scars, or bugs, which leave these red or blue stains human history as well All kinds of stuff Okay, continue so back to two son

Valories at this bar to meet up with two other scientists because they're all in town for this big conference an international Tree ring conference for all of the dendocrinologists in the Americas Is it like four people? Okay, how many people is it? Oh it total? Yeah an international tree ring conference. For all of the dendocrinologists in the Americas. Is it like four people? No. OK. How many people is it? Oh, it total?

Yeah. I don't know, maybe 200, 200, and 50 people. A lot. And among them were Valerie's bar buddies, Marta. Marta do Minga Del Mas. Spanish scientists. Specialized in dendroarchaeology. Studies the wood in shipwrecks.

What? Yeah. Like she dives down and examines the rings in the wood of the hulls of the ships that wrecked hundreds of years ago. Ah, yeah, the trisha is the wood. Third one. It's my name is Grant Harley. Grant.

Originally from Florida, I was born in the year. He's a paleoclimatologist. A associate professor of geography at the University of Idaho. Use his tree rings to study past and future climate. So it's one of the nights of this conference. So I think it was the last evening of the conference that they hit the bath. That they hit the bath. So they're sitting there drinking some beers.

Yeah, like we're sitting around this table and we start talking about this research project that I had to go on. And Grant says something like, I've got a puzzle and I'm not quite sure how to solve it. And I'm wondering if you two can help me out. Okay. So he says, for the last few years, I've been doing this research down in Florida, like all the way, like, almost to Key West, right near the southernmost point of the U.S. On this island called Big pine key big pine key studying

He's really gnarly pine trees that are basically like big bonsai trees and he tells Valerie and Mark to one day who's out there you know just doing his normal research which is like taking these pencil shaped core samples from these trees and he notices something he hadn't seen before core samples from these trees. He notices something he hadn't seen before. He said he saw these trillions. He's like really, really narrow rings. So narrow, he could barely see them. Super, super narrow, really, really small.

That automatic tells you that, wow. Something bad happened here. That tree was really stressed. So he's going through the list of things that he knows can stress out a tree. Drought. Maybe it didn't rain that much. And six can have a different... Maybe the tree got attacked by beetles. Or it was unusually cold.

Keep on going back to the drawing board to find out what is the signal in these tree rings. Until he comes up with a theory. Hurricane. Hurricane. But wouldn't... wouldn't Hurricane make a fat ring? Because it's bringing so much rain well I mean a hurricane as you know, it's pretty powerful. Yeah, according to Valerie a hurricane just Shred a tree. It doesn't just lose its needles. It can also lose its

Big branches obviously, but how would you prove that turns out? No one know what as in the government weather people As this data says it's just a big list of all the hurricanes that have happened in the Atlantic since 1851 that the government made by combing through old newspapers. And we compared that list to those years that he saw with very narrow rings. And they matched. Bingo.

In other words, he was right. They were caused by hurricanes. And Valerie says this match was exciting on a couple of different levels. For one thing, I don't think I'd heard about using tree rings to reconstruct hurricanes. It just felt like a new way to use tree rings to understand the world.

But also, it gave us new hurricane data, which we don't have a lot of. Because there are so few of them. So it's hard to calculate how frequently they happen Because you have so few data points coming data points exactly and what grant realizes is He might be sitting on a lot more hurricane data points because his trees the trees with the skinny rings that seem to represent hurricanes They go back Way further than the government data correct. They go back way further than the government data. Correct. They go back another 150 years

to 1707. So, grand thinking he might be able to use his tree rings to almost double the amount of historical hurricane data we have for this part of the world. Problem is he now needs something outside of the tree rings to prove that. And this is essentially the puzzle that he brings to Valerie and Marta at the bar. How do I prove this that this is hurricanes?

And Marta. Marta Dominguez del Mas is like, it's funny you say that because a lot of the shipwrecks I die that wrecked because of hurricanes. Entire fleet going down because of hurricanes. Entire fleets going down because of hurricanes. And so I just spit it out. And I'm like, what if we, what if we link the two? Like, what if you put the tree ring data, where you have the skinny rings that you think are hurricanes,

next to a big list of all the shipwrecks that happened for the last few hundred years, would they match up? Because if they do, we're seeing what? Because if they do, it's like the shipwrecks that happened for the last few hundred years. Would they match up? Because if they do, we're seeing what? Because if they do, it's like the shipwrecks and the tree rings are both showing us hurricane. It's like double reference, huh? Got it. So, okay, so they have this idea at the bar that night, literally the next morning they get together

and start looking around for a list of all the shipwrecks that have happened in that part of the world. And fortunately, there's a very good record, written documentary record of the Spanish shipping trade from 1492 up until it ends around 1825. And when they would wreck, they would keep track of where they wreck, when they wreck, why they wreck, whether it's pirates or hurricanes. To get their hands on this list, they eliminate the shipwrecks they know were caused by something other than hurricanes or that are in the wrong area or that, you know, we're not in the right time of year. And then Grant takes that shipwreck spreadsheet

and merges it with the free ring spreadsheet. And... I kid you not, they're almost identical. They match. You see the exact same pattern when you compare the shipwreck years to hurricane years with the tree rings. So it's like, okay, fat ring, no shipwrecks,

fat ring, no shipwrecks, fat ring, no shipwrecks, fat ring, no shipwrecks, narrow ring, tons of shipwrecks. And that, yeah, that was the moment where I'm like, yeah, this is it, this is working. Wow. There's something so like satisfying about possibly catching an objective possibly, an objective truth, an objective happening with these silent

bystanders is just like a tree. Yes. It just feels harder to come by these days. Yeah, you're spot on. That's what I really like about trees. You can't say the tree's saying this or a tree's saying that because you can see it right there in the wood. You can't make it up.

It's right there. Trees on light. Okay, and just so I am clear on what they are not lying about, I think what we've just learned is that the shipwreck data confirmed that grants skinny tree rings are, in fact, hurricanes, which means tree rings are now doubling the amount of hurricane data that we have? Tripling.

So, okay, so the hurricane data the government had at the beginning of all this went back to 1850, right? Then the tree rings extended it back to 1700, so they added like 150 years. But now the shipwrecks extended back even further all the way to 1495. Yeah, 150 to 450 years. Yeah, oh my god. So these three tree ring scientists basically tripled all of the historical hurricane data that we had with the Caribbean just by like winding up these three different data sets. So after they gathered this data, they sent it off to the people who make the hurricane models that, you know, predict how hurricanes are going to develop in the future. So,

now, those models can make better predictions, which could in turn, you know, save tons of money and That is so cool. Very cool. Actually, we're still just at the beginning of this story. So our tree ring scientists sent off this data to the hurricane modelers, but they also kept it for themselves because they're scientists. Trying to ring that spunk dragon as much science out of that is possible. And they want to see what else can we notice here. Cut to a few months later.

I was staying in this really cheap motel and flagstaff in a Northern Arizona. Valerie was actually on a research trip for a different tree ring project. But I was feeling really under the weather. And so while I was staying in and getting bored out of my head because I couldn't go to feel the work. I went to a coffee shop. She's at the coffee shop. I ordered a coffee. I set myself at the window.

And she's like, I'll just gonna work here. Pulled up the graph. The graph of the 300 years of shipwrecks, which also kind of stand in for the hurricanes. But anyway, she'd been toying around with it. She hadn't really found anything interesting in it yet. But then, I went to grab my coffee, Phantomone, I went back. From the counter, towards my laptop.

She noticed something in the graph that she hadn't seen when she was looking at it up close. Dis-dip. From 1645 to about 1715, where there were virtually no wrecks. No wrecks. That feels not hurricaney. Yeah, so like kind of like a grace period or something. Like it was like a 70 years of almost no hurricane. And what's you see? You can't.

I'd see it. All the weathermen between 1645 and 715 were like back to you, Doc. Yeah. So she's just like, that's weird. What is, what is that period? She's like, that's weird. What is that period? And the answer to that question,

it does do things, it reveals the secret about the sun that you almost certainly did not learn in school. Okay. And it also shows how this moment, this 70 year stretch, this clear skyd time of very few hurricanes. Sort of shaped the world we live in today. Huh. And we'll get to that after the break.

Lulu. Lutth. Radio lab. Lulu, why don't you just tell me what you have gotten? Where we are? Yeah, where we are. Okay. Okay, okay, okay. So we started a story.

This is a story about a drunk idea with follow-through. That's right. They woke up the next morning and actually went and chased it out. Nice. So the scientists have chased down this wild idea. They've matched tree ring data with shipwreck data. It's allowed them to look deeper in the past than ever before at hurricanes.

They discovered this weird lol. This time where there were less hurricanes. And then you were about to tell us how that lol shaped the modern world we live in today. Right. So Valarice is just lol. And she's like, that's weird, but also familiar. The dates were 1645 to 1725.

I'm like, I know those dates somewhere. From what is that period? It came to me pretty quickly. This period is exact period is to mounderminim. The mounderminim also called the monderminim. Okay. What the heck is a monderminim? It's a very well-known period of low solar activity.

A period when the sun was weak. Apparently the sun, the kind of solar radiation that comes from the sun, it's not constant. What? So the periods when the sun is like, my burners on high, my burners on low. Yeah, when the sun is at its peak, it's called maximum, at its lowest point, minimum. Huh. So does that mean that during the monitor minimum,

it was actually colder? It was colder than, yeah. And would it be darker? It would be just as bright. Just as bright. Just as bright, but just cooler. Yep, exactly. I don't know if you've heard of a little ice age.

I haven't. Started at've heard of the little ice age. I haven't. Started at the beginning of the 14th century and lasted roughly 500 years. And it's kind of the opposite of what we're experiencing now, right? Rather than glaciers retreating, you have glaciers advancing. According to Valerie, the coldest period of that little ice age was the monitor minimum. The fact that the sun didn't have as much energy

contributed to it being colder. And the colder temperature of that period that little ice age was the monitor minimum. The fact that the sun didn't have as much energy contributed to it being colder. And the colder temperature of that period might have meant cooler oceans, which in theory could mean less hurricanes. Because the fuel that drives hurricanes is really warm as he serves temperatures. If you don't have that, you know, it'll have a hurricane.

Huh. So then that could explain why there were fewer shipwrecks. During that time? Yeah. That makes me feel weird. Why? I just feel like for the deniers, for the human cause climate change deniers,

the phrase they bandied about all the time was like, no, there's natural cycles. It warms up, then it cools down. Yeah, natural cycles can't predict the weather. No, they do say that. Yep. So then is this showing that the sun does play some kind of role in climate change? No, not at all. This actually shows the opposite.

Check this out. Record breaking temperatures, record breaking heatwave. Dangerous heatwave. As we all know, in the last few years We have had the hottest years in the history of our planet some heat way unprecedented heat way It's gonna be a brutal couple days. It's like we're setting records all over the place, right? Yeah Whether stations are logging a sea of red as temperatures hit record high all of this has happened at a time when We're not even at a maximum yet.

We're in a week even though it's so hot. Yeah, exactly. Right now, we're in the middle of a smaller 11-year solar cycle. We hit the minimum in 2019. We're still ramping up. A lot more heat is coming our way. Oh, no. Yeah.

Okay, so back to Oh no. Yeah. Okay, so back to the story. Okay. So Valerie was in the coffee shop, saw the lull and the shipwreck data, and she recognized it as the Mondar minimum. But when Grant looked at that same time period, period of the coldest period of the little,

I say 1645 to 1750. He recognized something else. The Golden Age of piracy. The Golden Age of piracy? something else. The Golden Age of Piracy? The Golden Age of Piracy. Grant is a big fan of pirates, has been ever since he was a kid. Turns out this is common knowledge among pirate nerds, but in almost these exact same years, there was an explosion in bands of pirates, basically robbing and hijacking ships, in the Caribbean specifically,

and in the Atlantic more broadly. Like, it was when piracy became, first of all, more common, but also became way more culturally visible. Many of the most famous pirates, you know, have came out of this very period. Are you going to tell me who? Henry Morgan, aka Captain Morgan. Captain Morgan. He's real? Yeah.

We have Captain of Spanish galleon. And Bonnie and Mary Reed. If I had a pistol, I'd shoot at your gizzet pen. Black beer. Black beer. I'd be black beer. Huh? And even if you've never heard of any of those people,

you've definitely heard of... Parks the Caribbean. Oh my gosh, really? Yeah. You are without doubt the worst. Pirate of the bad. This is the age where the mythology of Pirates of the Caribbean emerged.

This, by the way, is Matt Casey. I am a specialist in the 20th century history of Haiti and Cuba that the University of Southern Mississippi. He and Grant actually met on a bus, on a field trip. To our bus, right? To New Orleans. And I'm not even sure that we talked the whole two hours, but very quickly within the conversation,

we realized that we had a lot in common. Among the things they're love for the golden age of piracy. And at some point, Grant asked him, do you think that this law in hurricanes that we found in our data could have caused the golden age of piracy? And I became really excited because, yes, for a historian of the Caribbean, this just makes so much sense.

Huh. Matt says, of course, there's no one cause for anything in history. There are million explanations for the Golden Age of Piracy. There are social reasons, political reasons, economic, cultural, all these different reasons, why pirates were in ascendancy at this time. But the fact is, pirates spend a lot of time on the water. And so, as fun as it is to see them as these kind of masters of the sea who just take a licking and can do whatever they want, they're absolutely vulnerable to the elements like hurricanes. So less hurricanes could mean a better environment for

pirating. Yes. But that was not my first thought. Matt Casey says when he looks at this period of time, this this lull in hurricanes that lines up with the Mondra minimum, that lines up with the golden age of piracy, he sees it lining up with the whole other thing. This is the moment that shaped the history of the world in a way that people don't always recognize. The world? It sounds like an exaggeration,

but that is not too hyperbolic. And this moment Matt says is the sugar revolution. The sugar revolution. One of the first places where sugar production occurred on a large scale is in the Caribbean. Probably 1620s or 1630s. It was this massively pivotal moment in world history, Matt says, where European plantation owners brought thousands of people against their will. Enslaved Africans, indentured Europeans, out to these islands in the Caribbean to produce sugar.

On an enormous scale, people refer to a sugar plantation as a factory in a field. Between 1615 and 1725, hundreds of thousands, by some accounts nearly a million, people were kidnapped to work in the Caribbean Many died horrendous and in the scale of human tragedy and in roughly that same time period Sugar consumption in Europe quadrupled that sugar produces

massive amounts of wealth so much so that European industrialization was actually paid for by so that European industrialization was actually paid for by how lucrative sugar was in the Caribbean. A lot of historians, including Matt, argue that the profits from the sugar plantations were the startup capital of industrial capitalism in England. And that these profits not only funded the industrial revolution, but essentially gave birth to modern capitalism itself. And the way Matt sees it, part of what allowed for all of that to happen, the boom in sugar production, the expansion in slavery, the birth of capitalism, is this decades-long, modern minimum, lull, in hurricane. It was it was a moment of calm weather that let the plantations flourish,

the ships sail filled with pirates, but also enslaved people and sugar and money. This period of stability, it subtly enabled all of that to happen. Okay, we're okay, okay. What does this all have to do with trees? Right. So trees is kind of the way they notice this like subtle, rubbed, goberg machine that has been playing out over centuries, right? Okay.

Meaning what? Yeah. What are the bells and whistles? Right. Okay. What are the bells and whistles? Right, okay, well so basically these three scientists in this bar, they use a combo of information they got from tree rings and information about shipwrecks to discover this 70 year period where the sun was dimmer, which somehow led to fewer hurricanes. The sun was dimmer, which somehow led to fewer hurricanes. And that 70 year period had this sort of disproportionate effect on agriculture, on basically

slavery, on capitalism, on the way our modern world gets made. Maybe. This is not a big theory. And I think the thing that makes this story worth telling right now is like all of that, the modern minimum, their estimate is that that was about one degree Celsius of cooling. And now we are doing, we are doing this to ourselves,

but like in the reverse, we are now the sun. Whereas the sun called the planet down by one degree, we are now turning up our own thermostat by two degrees, maybe. Can we keep it to two degrees? To me, it's like we're changing our climate and what new possibilities, and even kind of, what new cruelties, like, are we gonna unleash, are we gonna open up? I don't know, I don't know if you can say for sure,

it's unimaginable. This story's just ramping my fear. Like does that give you anything other than just like, make you wanna lie down and, and, and, I think it does. Like I think it's like, I think it's like, so we're like mere cats, you know? How so?

We're like running around foraging for little grubs. And then every once in a while, like one of us stands up and looks around. Like that's to me what they did in the bar. Like it's like one of those moments of like, standing up, looking around, being like, whoa, there's a big picture here. Mm-hmm.

Standing up, looking around, being like, whoa, there's a big picture here. Mm-hmm. It takes those kinds of, uh, like, bar, bus, whatever, wherever, moments to, like, kind of, sit back and be like, wait a second, all this stuff is connected. Like, all this stuff is, like, we're trying to, like, divide up the world to make it comprehensible, but it's actually all woven together. This episode was reported by Lachifnasser, with help from Aketi Foster Keys and Maria Paas Gutierrez, produced by Maria Paz Gutierrez and Pat Walters with help from a Kedi Foster Keys and Sachi Kichijima Mokki. Mixed by Jeremy Bloom with mixing help from Aryan Wack, fact-checking by Natalie Middleton and edited by Pat Walters.

Big thanks to this episode to Scott St. George, Nathaniel Millet, Michael Charles-Stamba, and Justin Maxwell. That's all from us. Thank you so much for listening. Go thank a tree. Go thank a tree. For its service to history. And for its shade that helps keep you cool by maybe one degree Celsius. Who knows? Yeah. All right. See you soon.

Okay. Bye-bye. Alright, see you soon!una, David Gabel, Maria Paz Gutiades, Sinden Yana Sanbanbaum, Matt Kilti, Annie McEwan, Alex Neeson, Sara Curry, Anna Vaskudbaz, Sarah Sandbach, Erin Wack, Pat Walters, and Molly Webster, with help from Satchikita Gimomolki. Our fact-truckers are Dian Kelly, Emily Krieger, and Natalie Middleton. Hi, this is Jeremiah Marba,

and I'm calling from San Francisco, California. Leadership support for Radio Lab Science Programming is provided by the Gordon and Betty Moore Foundation, Science Sandbox, Simon Foundation Initiative, and the John Templeton Foundation. Foundational support for radio lab was provided by the Alfred P. Sloan Foundation.