What Fossils Reveal about Today’s Climate Change
This episode is brought to you through a collaboration with the Smithsonian’s National Museum of Natural History in Washington DC, and the Field Museum in Chicago, Illinois. [Emily VO] Hey, so my time is almost up here in the US capital. But, before I left, I had a chance to sneak in and see part of the construction of the Natural History Museum’s new “Deep Time Hall”, which is reopening in 2019 after being completely overhauled and rebuilt over the last five years. When it’s done, visitors will be able to learn about the history of our planet from the formation of the earth, to present-day, with a look to the future. To help us understand this concept of “deep time”, let’s use the Washington Monument as a scale bar. Here’s the formation of our planet, down here at the base – 4.5 billion years ago. The earliest evidence of life took the form of single-celled organisms around a billion years later. Then, the first multi-cellular life shows up. Very early animal groups join the party during the Cambrian Explosion around here. Oh and here’s our friend Dimetrodon, who by the way is not a dinosaur. But, around 232 million years ago we get our earliest dinosaurs, and they largely get wiped out by an asteroid here. The first known flowering plant is pretty late to the party, but honestly so are we. The earliest humans, Homo habilis, evolved a little over two million years ago. And, Homo sapiens didn’t make it on the map until just around 300,000 years ago, right up here. To get another perspective on this concept of “deep time”, I went to chat with Dr. Kirk Johnson. He’s the Sant Director of the Natural History Museum, and a paleobotanist. He studies fossil plants, and has been working on the Deep Time Hall renovation project for years. Emily: So, how do you deal with that interplay between technology accelerating at an unprecedented rate, but you’re focusing on a Deep Time Hall? Kirk: We live in a world where it’s not just changing, but the rate of change is changing, which means that this Hall has to be future-proof to some degree. And, what we’re doing is actually challenging our visitors to see themselves in their part on the story of our planet, which is what other halls don’t do, and also see themselves as agents for a positive future of the planet. Emily: How do you do that? I mean you as a paleontologist – I mean you’re constantly looking at the fossil record, your work is in the fossil record, your research is looking at things that when extinct or died, you know, tens of millions of years ago. How do you take your background as a paleontologist and interject that into this idea of looking to the future to make decisions that are going to be better off for our planet? Kirk: Well, I mean, paleontology is all about discovery. You’re looking for things and you find things, and that’s what’s so cool about it. And, for me, it’s really helpful to know the history the planet, because it helps me understand what’s going on now. Take climate change for instance, we know a ton about climate change by looking at what’s happened in the past. And, for almost all the stuff we’re presenting in the exhibit, we’re using specimens that we’ve had for 200 years, but concepts we’ve had for as little as 10 years. So the science that’s going through this hall is the latest science, and it’s got this “future-cast”, which is quite amazing. [Emily VO] On the topic of both the discoveries in paleontology, as well as looking to the fossil record to better understand current climate change events, we went to interview the Curator of Fossil Plants, Dr. Scott Wing. Like Kirk, he’s a paleobotanist, but his research is focused on something called the “Paleocene-Eocene Thermal Maximum”, or the PETM for short. Simply put, the PETM was a massively significant global warming event that happened around 56 million years ago, or about here on the Washington Monument. During the PETM, something triggered a huge release of carbon into the atmosphere that lasted for a few thousand years, and it significantly warmed the planet. The global temperature increased by five to eight degrees Celsius or around nine to fourteen degrees Fahrenheit. This led to a variety of ecological and environmental changes. There was ocean acidification and deep sea extinctions. On land, many vertebrates began to shrink in size, as the CO2 in the atmosphere caused plants to become less nutritious. And, there were other floral and faunal changes occurring, as sea levels rose and the planet became warm and wet. The PETM lasted for around 180 thousand years. And, although the impact of the PETM carbon release happened over a period of time that’s a hundred times longer than the human caused carbon release that’s happening today, it’s still the best proxy for helping us understand the long-term effects of today’s human-caused climate change on our planet. But, there’s still a lot of work to be done. And, as you’ll hear from Scott, it can take years to scratch the surface. Emily: How is this event even discovered? Scott: Well, it was discovered initially in drill cores from the Southern Ocean from off of Antarctica. Antarctica is where the coldest densest water in the ocean forms today, and that really has a huge influence on the circulation of water in the global ocean. So the question was, how long has that been true, has that been true for millions of years, what about back when it was generally a lot warmer than it is today? So, you have to imagine a big drilling ship, a bunch of scientists on board, [and] labs – they’re bringing up cores. So, they were there to get a sort of long-term record of what happened over the last 70 million years. And, what they had noticed was there’s an extinction event that they didn’t really expect to see. So, people published papers on these cores from Antarctica. The next year a couple of other scientists working in Wyoming, where I had been working for a long time, said, “Oh, we see, what we think is the same event, in rocks deposited on land in Wyoming”. I thought, well, if there’s a warming event, I work on fossil plants – plants are really sensitive to climate change – I should go find plant fossils in the period of time when there was that sudden warming, because that’s gonna be really interesting. Emily: So how did you find these fossils? Did you just get out of your truck and walk 20 feet in the other direction, and boom there they were? Scott: No, no. Yeah, that would have been really nice. I knew sort of about what level I was needing to look at, but I didn’t know exactly where, and I didn’t know where the plant fossils would be, because I hadn’t looked for them exactly in that zone. This warm period is about a hundred thousand years long. A hundred thousand years sounds like a lot, but it’s a hundred thousand years in the middle of a pile of rocks, in that part of Wyoming that represents about ten million years. You know? Emily: You’re looking for a tiny sliver. Scott: It’s the needle in a haystack. Emily: The needle in the haystack, a PETM fossil deposited in the Big Horn Basin in Wyoming. Scott: Right. Emily: That’s a less relatable analogy. Not that (Scott: Just a little bit, yeah.) that people are finding needles in haystacks, right? Scott: Yeah, so I set out looking for them. That was 1993. I went out every summer for the next 10 years. Emily: It took you 10 years?! Scott: Yeah, well 10 years before I found an area where it looked like there were going to be plant fossils, and then it another 2 years to find really good ones. I mean, there were other things too. I wasn’t just wandering around like a crazy guy lost in the desert. [Saying] like , “Where my fossils? They must be here someplace!”. Emily: So, what was this moment of discovery like? Scott: It was very storybook. I was out with a guy who just graduated from college, and he had never been in the field before. And so, we walked for a couple of hours up into these hills where I knew the rocks would be the right age, in general. I said, “Oh, you know, I just need to check that out”, because I saw something that looked like maybe [the right fossils]. I dug into the hillside with a shovel, and out pops a little plant fossil. It kind of looked like this and I knew immediately I had never seen anything remotely, like it. I get down and I’m digging with the shovel on my knees, trying to see what else is in there. Out pops another leaf! I just started to laugh, because this is absurd, because it was exactly what you’d expect! So I started laughing, and then I started to cry because I was really happy! And then I remembered that I wasn’t by myself. Emily: [laughs] Scott: I had kind of forgotten that I had somebody with me, because it was very exciting! In science, I had not had many “Eureka” moments, you know that sort of, “Oh, that’s it!”. That doesn’t really happen very often because it’s usually more incremental. So, you usually sort of slowly realize something. But no, no, it was like 4:04 p.m. on July 3rd, 2005. Emily: [Sarcastically] It’s not like you committed that date to memory? Scott: Yeah. No, I did. Yeah, that’s actually it. Both: [laugh] Emily: So what did you do with that information? I mean, because now the search is over and now the work begins. Scott: Right, exactly! Well, we made a big collection. That took two years – two summers of work, because that’s what it takes. Emily: Rocks are heavy. Scott: Rocks are heavy, they’re hard, they’re fragile. So, [then] I spent basically another 10 years looking for more places. Emily: Why is this a significant climatic event in our Earth’s history? Scott: It is the closest thing we have in the geological past to what we’re doing right now. Along with the warming, we have really strong evidence for a huge release of carbon into the atmosphere. We think that the the carbon release may have been triggered by a volcanic activity. It’s quite possible that that triggered the release of other reservoirs of carbon. And, then you change the climate, and you may start to cause the bacteria in soils to get very happy because it’s warmer, and they eat more of the organic matter in soils, and that puts even more CO2 in the atmosphere. So basically, it’s a trainwreck and it just goes “pew”, and that’s why it warms so quickly. Today, carbon release is a little bit simpler. It’s mostly caused by burning fossil fuels. 15 percent of it’s caused by deforestation, land-use, activities of humans. Except, what’s happening now is happening even faster. Emily: How does it resolve itself? Does it resolve itself? Scott: After about a hundred and fifty thousand years of being really warm, it starts to cool off again. A combination of weathering and productivity are pulling the CO2 out of the atmosphere. Emily: So at one point you mentioned that it’s important for us to think in a geologic timescale, rather than thinking in a human time scale, especially as there are policies and and other decisions being made today, that are contributing to the overall warming of our planet. What is that? What does it mean to think about thinking a geologic time scale versus a human time scale? Scott: Yeah, I think it just means to be aware. We can’t just think about next year, or ten years from now, or a hundred years from now. Because, the things that we’re doing today are going to have an impact in a hundred, or a thousand, or 10,000 years. It’s really like “Spider-Man”. Emily: Really? Scott: Yeah, yeah, you know well… Both: “With great power comes great responsibility.” Emily: It’s true. Scott: Yeah, and there’s the time dimension to that responsibility. Emily: So what does this mean for Natural History Museum’s looking to the future? Kirk: I mean, if you think about it, these museums all were built during the time of big urbanization between 1880 and 1920. So at the end of 19th century, was the formation of the big temple-like buildings in urban areas. And, people are moving into the city, away from the countryside. They were learning that there was stuff to be preserved. Like, herds of bison were disappearing, and people naming National Parks. And then the 20th century happened! The 20th century went by fast, but it had the World Wars, it had the Depression, it had the Cold War, it had Sputnik, and it had the rise of science centers. And all that time, the natural museums got lower and slower, and lower and slower, and lowered. So by the early 80s, they looked like 19th century institutions, but they weren’t because they were these places where families work to learn about the natural world and people kept going. So, they really are 19th century organizations that are dialing forward into the 21st century. And our message is the same, but changed. Right? The same because we’re really worried about the natural world and humans’ impact on it. That was our original mission. It’s our mission now. And, we’re trying to prepare people to realize what the impact of humanity on the evolution on their planet is. And, this is how we do it: by telling the story of our planet, and then making them realize that they’re part of that story. Emily: I’m convinced. Kirk: Okay, good, done. Emily: Yeah, you’ve got my money, but you’re a free institution. Kirk: Oh, that’s right, but we’ll still take your money. Emily: [laughing] Okay? Emily: It still has brains on it.