PM x Radiolab: Can the economy grow forever?

0:00Support for NPR and the following message come from Edward Jones. What does it mean to live a rich life? Maybe it's full of brave first leaps, tearful goodbyes, and everything in between. And with over 100 years of experience, your Edward Jones financial advisor can help. Edward Jones, member SIPC. This is Planet Money from NPR. A few weeks ago, we got this kind of mind-bending question. It was from our friends at Radiolab, which is a show about science and philosophy and, you know, just the sheer joy of curiosity. In this case, they were curious about growth, in particular, economic growth. How could it possibly go on forever?

0:47And can too much growth destroy us? And in trying to answer their big question, we ended up in some pretty heady and unexpected places. Hello and welcome to Planet Money. I'm Jeff Guo. And today we're doing something a little bit different. We've teamed up with Radiolab and we're going to try to answer one of the biggest questions that often goes unsaid in economics. Here's Latif Nasser from Radiolab to get us started. Hey, this is Radiolab. I'm Latif Nasser. What got me thinking about economic growth was not all the stuff that's in the news, the tariffs, the fear of the recession, all that stuff that everybody's talking about.

1:25What started it was a lecture I heard a little while back by, of all people, an astrophysicist. So I'm going to sketch what we know about Earth's history, cosmically speaking. Her name is Sandra Faber. She goes by Sandy. Brilliant scientist. She co-authored the standard model for thinking about how galaxies form. She won a National Medal of Science back in 2011. and she started the lecture by saying, we have a pretty happy little planet to live on. Earth is a good place to live for, let's say, of order 100 million years at least. Should be livable for a really, really long time. Okay. Except, she goes on to say, for us.

2:14Over the last century or so, we've been seeing planet-wide GDP growing exponentially. So what she did is she took the average gross domestic product worldwide, and that's a rough measure of economic growth, and that had been growing recently around 3%, which for economists is like a happy little growth number. You will recognize 1.03, 3 % as the... But Sandra took that 3 % and with some quick math, she started to just play it out year after year. And in her lecture, she's showing this chart where you can see this curve just shooting up. We can see this number is completely ridiculous. And she was basically like, look at all that growth.

2:59That's eating up Earth's resources. A large number here is bad because it means that we want more of that product. And so even though Earth should be good for 100 million years, we're going to just eat the planet up. We're going to devour the physical material level of this planet. We're going to eat it up in more like a couple thousand years. And my concern is that we're not talking about this. And when I heard that, that was breathtaking and horrifying. And honestly, like I haven't been able to stop thinking about that number. Three percent sounds like a specific thing, but also it's kind of abstract and mathy.

3:44And I wanted help. I wanted help to parse this out. Like, how bad is that really? How bad could that possibly be? And so I turned to someone whose job it is to literally make sense of this exact kind of thing. Hello. Hi, how are you doing? Hi, I'm doing well. How are you? And we had what I felt like was a kind of a roller coaster of a conversation. So I'm just going to play it for you right now. Yeah. Okay. So I am Jeff Guo. I'm one of the hosts of the Planet Money podcast at NPR. Terrific show. Thank you. um and uh i i guess what do i do i talk about economics all day that's oh my god that's what i'm i need you i need you to help me it's more than scratch and itch i need you to help me cure this existential dread that you have now that's exactly right yeah yeah okay um well i mean i guess where i would start is and you know i would hate to contradict a nobel prize winning astrophysicist.

4:49It sounds like, you know, starting out on dangerous territory there. I mean, well, she won the National Medal of Science, not the Nobel. She's gonna, she's gonna. It sounds like she's gonna win. Okay, yeah, sure, fair. But you did ask me to kind of look into what things are we going to run out of? Yes, yes, yes. Oh my gosh, I'm so excited.

5:10After the break, can we cure Latif's existential dread? Or did we just make it worse? support comes from our 2025 lead sponsor of planet money amazon business how can you free your team from time-consuming office tasks amazon business empowers leaders to not only streamline purchasing but better support their teams smart business buying tools enable buyers to find and purchase items fast so they can focus on strategy and growth it's time to free up your teams and focus on your future learn more about the technology insights and support available at amazonbusiness.com This message comes from NPR sponsor U.S.

5:50Bank. With U.S. Bank Business Essentials, you get more than just a bank. You get a dedicated partner that provides you a powerful combo of checking and card payment processing with quick access to the money you've earned, proving that there is nothing as powerful as the power of us. Visit usbank.com today to learn more. Member FDIC. Copyright 2025 U.S. Bank. Okay, Latif. So I looked into your question about growth and stuff that we might run out of, and I found a couple things that, you know, people are worried about. Okay, great. And I just did some very rough back of the envelope math. Like, this is so totally not precise.

6:30My favorite kind of math. My favorite kind of math. It's so hand-wavy. Great. I love it. Okay. So I don't know what should we start with. Copper? Yeah, that's a big one. Copper's a big deal, right? Very big deal. So if you look at copper consumption over the past century, since the Industrial Revolution, you know, our demand for copper has grown about 3 % every year. OK. Like, you know, in recent years, it's we've consumed about 26, 27 million tons a year of copper. Yeah. Yeah. So if you just, you know, extrapolate that out, if you just assume copper is going to keep growing at 3 % every single year.

7:10Right. Fair. Fair assumption. I looked up how much copper people think we have. According to geologists, what we know is out there and could theoretically get to. And that number right now is five to six billion tons. OK. It's not nothing, but we're using it pretty quickly. And if you just assume that that this number is going to keep growing at three percent a year. Yeah, yeah, sure. It would take about maybe another 70 years and then no more copper. That's it? 70 years? 70 years. OK, so that sounds terrible. It's true. It's true. That's assuming, of course, that, you know, we do keep consuming copper that quickly.

7:45Using copper and needing copper the same way that we are. Yeah, yeah, sure. T minus 70. Yeah. No copper. No copper. For anybody. No copper. Okay. Okay. So then what? But then, so that's, this seems to point exactly to Sandy Faber's point, right? It's true. It's true. It's true. Yeah. Do you want to do another one? Oh, that's the end of it? I thought you were going to be like, but there's a giant, there's a copper thing that we're going to. No, there's no but. That's it. It's just like, yeah, she's right about copper. Okay, but there's a but. There is a but coming up. There's a but. Yeah, okay, okay, okay, okay, okay, wait.

8:15You want to go through more of them before we get to the but? Is that the idea? Yeah, yeah. Okay, okay, okay, okay, okay. Next one, okay, next one. Okay, so another one I looked into is sand. Okay, yeah. Sand and gravel. Which seems like there should be a ton of that. Seems like there should be so much of it. Yeah. And you know the reason why we need sand, right? Why do we need sand? For concrete. Ah. So it's actually so important that we don't know how much we're using. Oh, my God. Like, we're using so much. We just, we actually don't know. But, like, ballpark estimates, we're using maybe 50 billion tons of sand and gravel every year.

8:53Okay, that sounds like a lot. I don't even know. I can't even visualize that. I don't know. It's a lot. Right. And I couldn't even find how much sand and gravel there is in the world. Like, nobody actually knows. This is one of those numbers where it's like, oh. But we're doing like back of the envelope math here, right? Right. So I was like, well, if we don't know how much sand and gravel there is in the world, surely we know how much rock there is in the world, right? Totally. Totally. So I looked it up and according to geologists, the Earth's crust, all of the Earth's crust, contains maybe like 23 quintillion tons of rock and stuff.

9:35Okay. Okay. But it does seem like the whole point of sand is that it's like teeny tiny. Like it would take a lot of energy to turn that rock into sand. It would. But assuming that we're able to do that, right? Okay, okay, great. Assuming that we're going to use sand and gravel at a rate that grows by 3 % every year, year after year after year. Yeah. It would take about, do you want to guess how long it would take to deplete the entire Earth's crust? Wait, so a quintillion based on the growth rate and the uses now. I would imagine this one is going to be, this one is not on Sandra Faber's side.

10:12I'm going to guess this one is like way, way, way far from now. Like this is going to be like a million years or something. Five to 600 years. That seems so short again. It does, doesn't it? That is way shorter for the whole crust. I know. Oh my God. God, that's not like it's long, but it's not that long. Like that's like that is nuts. All right. I got a couple more. It's just making me more and more existentially worried. Okay. That's how I felt. That's how I felt when I started on this journey. Right. I got a couple more. Okay, great. Love it. I got to pull up my spreadsheet. I'm going to talk about lithium.

10:53Okay, great. Good one. Good one. And lithium, you imagine there are like those giant deserts filled with those like sand flats or whatever. right? Yeah, in Bolivia. In Bolivia, yeah, yeah, yeah. Yeah, okay, so this one will be again, like, I think this one, I feel like there's gonna be a curveball in here where you're like, no, no, no, we have enough, that, enough for, you know, for millions of years. Anyway, okay, keep going. Okay, hang on, let me see, let me pull up my, where did my notes go on this? I can't wait when we have to fact check all of this.

11:25Okay, lithium. So we are using about 190, 200 ,000 tons of lithium every year. Right. That's kind of. So that's like in, that's in phones, electric cars, da, da, da, da. Yeah. Batteries. Batteries is a big one for lithium. Yeah. Very important. Lithium consumption, of course, has been exploding. So over the past decade, lithium has been growing. Do you want to guess how much it's been growing? What, like 5 % or 10 %? On average, around 20%. Okay. Wow. Okay. Wow. So we need a lot and we need a lot more lithium. Which is good, which is good, which means like more electric cars, more da da da da, right?

12:04More recyclable batteries and stuff. That's great. Yeah. So geologists think that of all the lithium that we know is out there, there's probably like 105 million tons of it. Like out there. That sounds a lot less than the sand you're talking about. Like this doesn't sound, this is going to get worrying. Okay, keep going. Right. And so, you know, if you do this whole, you know, the same math and you just if you assume if you just assume just, you know, for the sake of argument, it's only going to grow at three percent a year. Right. Yeah, sure. We'd probably run out of lithium around about March.

12:39I feel like you're going to say like I feel like you're going to say like so soon. Tomorrow. About about 100 years. OK, 100 years again. It's not bad. No, it's it is bad. It's bad, Jeff. It's bad. We need that. Like, we're going to need that later for even better stuff. It's true. Okay, keep going. I'll do one more. I'll do one more, which is, this is a big one, oil. Really scary one. Yeah. But hopefully we're weaning off of this one. So maybe this one is a different. Hopefully. Like it's going in the opposite direction. Hopefully. Doesn't seem like it's really happening yet. Oh, God. But. But.

13:16I don't think you have had a single piece of good news here. Just wait for it. Okay, all right. So if you look at oil, right, how much do we consume every year? About 37 billion barrels of oil as a world. How much is left? Probably 1.6 trillion barrels. Really? Yeah. So it's not. That's a lot. It's a lot, but it's maybe less. It's less than I thought. So another way to say 1.6 trillion is 1 ,600 billion. Right, right. So 37 billion a year. We have about 1 ,600 billion barrels left out there. Yeah, when you say it like that, it sounds quite alarming. Not great. So, you know, if you do the math again, exponential growth, very scary.

14:00But we do want to use less of it anyway. Right. Yeah. I'm ambivalent about this. We're trying to. Yeah, yeah. Okay. About 28 years. No way. That is nothing. 2052 might be the day we run out of oil. Wow. Maybe. Maybe. I was worried about when Sandra Faber said we had thousands of years and you're like you're you're taking me even an order of magnitude less. Yeah. Maybe decades. Yeah. So I started to get, you know, a little nervous. And so I thought, well, like what happened in the past? You know, like when we were over exploiting some resource and it looked like it was going to run out. and when I looked into it, there's this funny thing that happens.

14:48So just for example, let me tell you a story. Please. It's about medieval England. Okay. So it's the 1400s, okay? It's like medieval England, it's the 1400s and this amazing new technology has just arrived on the shores of Yolde, England and it is this new way of making iron. Okay. It's called the blast furnace. So just like very briefly, like before the blast furnace, you kind of had these backyard ovens, basically, where you kind of baked the iron ore to make the iron. And they were like super inefficient and really slow and not great. Okay. But this blast furnace, the scientific innovation was that if you blew air onto the fire, you could get it really hot.

15:32And then you could get it so hot that you could just melt the iron. And it was amazing. Got it. And this, like, revolutionized iron making. So these blast furnaces, they're these huge 20-foot tall stone towers. You would have these giant bellows at the bottom blowing in air. I was just imagining the bellows. I was just imagining the bellows. Okay, cool. Okay. So that's the key innovation here. Yes. And medieval England, iron was so precious, so important. You needed it for plows and spades, horseshoes, pots, kettles, nails, hammers. Yeah, whatever. And so now you had this technology that you could make.

16:09These blast furnaces, they could make a ton of iron a day. A ton, a literal ton. A literal ton, which is like just unprecedented. Yeah. The problem with all of this is what was the fuel that went into this blast furnace? At the time, it was charcoal. Which is charcoal is made out of wood, is that right? No. Yes. Yes. Yes. So this was not as good. So they're like slurping down forests, basically. Yes. Yes. Just picture the English countryside, right? You have these blast furnaces sending up these huge plumes of smoke. And then everyone's just chopping down trees as fast as they can to feed these giant blast furnaces.

16:45It's yeah. And it makes people really concerned. Yeah. Like really concerned. They're like, oh, my God, where are the trees going? But it got so bad that by the late 1500s, you have parliament banning new iron mills from starting up in different places. They're like, we cannot do this. We just cannot deal with this. Because we have one tree left and everyone's about to cut it down. We got to save the trees. The tree. Yeah. Yeah. You even have Queen Elizabeth I. Not the second, the first. Okay. All right. You have Queen Elizabeth I. She is issuing royal edicts saying, no more charcoal making in my royal forests.

17:26Wow. We just can't do this anymore. But then something happened. Okay. So in 1709, this English guy named Abraham Darby, he figured out how to use a different kind of fuel. So not charcoal. So maybe you want to guess what he figured out. Oil, probably, right? Coal. He figured out coal, yes. He figured out you can use this sort of modified coal to run these blast furnaces. And this changed everything. I'm not exaggerating. The iron industry took off. This led to the Industrial Revolution. We avoided the problem. We avoided the shortage. And it's not an isolated example. This is a pattern that comes up.

18:11We did this with whales. When we stopped using whale oil for lamps and started using kerosene, we did this with rubber. We started making synthetic rubber instead of getting all our rubber from trees. It's happened over and over again. We have stood at the edge of the cliff where it looked like, oh, crap, if we keep doing what we're doing, we are going to run out of some precious resource. Right. And then somehow at the last minute, catastrophe is averted. I mean, this has happened so often. I feel like we should give it a name. I know. I was going to say, do economists have some kind of like wonky name for this?

18:50Not that I could find. So I'm going to take the opportunity to give this a name. Jeff, it is yours. Yours to name. Okay. I think we should call this the Malthusian Swerve. Swerve. Malthusian Swerve. Mm-hmm. Okay. And why that? Because remember, do you remember Thomas Malthus? Yeah. And if I remember, his whole thing was like, you know, you tell me what his whole thing was like. Yeah. So he was this famous English philosopher type. He lived, you know, he grew up in the 1700s. pretty much around the time that coal was taken over england yeah yeah yeah right so he was seeing a lot of this happen and he's famous for predicting that humanity's growth would hit a limit that you know populations would grow faster than we could provide food for them right and so the future of humanity was to be limited and trapped by our own lack of resources and that everybody would just be miserable and sad and poor and hungry forever he he does not sound like he would have been fun at parties.

19:55Yeah, yeah. He's a real bummer. But maybe what he's more famous for is that none of that happened. The reason that Malthus' prophecy didn't come true is due to what I would say is the most important Malthusian swerve of all time. Okay. And this one is fertilizer. Right. Right? What was it, like the Green Revolution or whatever, right? Is that right? The fertilizer revolution. Yeah, Yeah, yeah, yeah. Yeah. So I don't know if you want to hear the guano story. Please. I love the guano story. We can do it quickly. I know the guano story, but I love the guano story. And I want to hear you tell the guano story.

20:33Okay, let's do it together then. Yeah. Okay, let's do it together. So this is like the 1800s, a little bit after Malthus's time. In the 1800s, Europeans are starting to realize you can really supercharge food production if you use better fertilizer. Yeah. Right? And specifically, there's this one fertilizer that indigenous people in South America were using that was amazing. Guano. Guano. Which is basically just bird poop. Yeah. Right. Okay, so basically you would have all these seabirds and they would poop on these rocky islands and coastlines along South America. And the poop would just accumulate.

21:09So the Europeans, so like in the 1800s, the Europeans are importing hundreds and thousands of tons. They're literally fighting wars over control of these guano islands. Like Spain is getting into wars with Peru and Chile. Yeah. Like, just who gets to seize the poop islands? Right. But the problem is, we were using guano way faster than the birds could, you know, make the guano. Yeah, yeah, yeah, yeah, yeah. And then, in the 1900s, in the early 1900s, some German chemists figured out a way to basically make synthetic guano. They invented an industrial process to literally pull nitrate. Nitrogen.

21:50Yeah, that's like the key ingredient in guano. Right, right, right. pull it out of the air and make synthetic fertilizer. And that is on the order of like alchemy discovery. Like that is like this thing that is super abundant in the air all around us. It is literally the majority of the air, but it was unusable. And then there was a hack where we then figured out how to make it usable. That seems like, that's like a miraculous technological breakthrough. Yeah, it's a miraculous story. And it is like maybe one of the best examples of this thing that I'm going to call the Malthusian swerve. Swerve.

22:28I like it. Right. I like it. And the swerve. So the swerve is like, it's like, like when you say swerve, I'm picturing like it's like a car about to collide into a cliff and then right at the last second. Whoop. Swerves out of the way. Yeah. And Malthus is driving the car thinking that, of course, we're going to hit the cliff. And then really it's like the passenger who then just like yinks the steering wheel. It's like, nope, not going to happen. Right at the last second we figured it out. Yeah. And if you look at human history, this is a pattern that happens over and over again.

23:08I find this somewhat of a relief. It is sort of encouraging. but it also seems like there's so much drama here. And there might be a time where we can't swerve in time. Like what happens if and when we can't swerve in time? And also I would argue sometimes the swerves, sometimes we swerve right into another cliff. So for example, the example you talked about From charcoal to coal, which is great for the trees, except after a while, it's also bad for the trees, right? Like, it's like global rising temperatures lead to wildfires, lead to trees not able to grow where they once were able to grow. Like, it's like we're— It's true, but we've bought ourselves more time.

24:06Fair. Right? We've bought ourselves more time. But then we just always use that time to step on the gas to the next thing, right? And then maybe when we do swerve, then we swerve into something worse, something that causes, you know, war or exploitation or just messes up the planet in a way that is unswervebackable from. I mean, yes, that is all totally right. It is a mess. But, you know, to help us unpack it, I think we should talk about a swerve that we are in the middle of right now.

24:44Actually, first, we're going to swerve to break, but only for a minute. Then we'll swerve back and step on the gas directly towards a currently oncoming cliff.

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25:43Adobe Acrobat Studio. Learn more at adobe.com slash do that with Acrobat. So we have been talking about a couple historical examples of this, this thing I'm calling the Malthusian swerve, where it looks like society is about to run out of some resource, but at the last minute, some new resource or idea or innovation comes along and saves the day. And when I was looking into this i was like okay is there a more recent example is there an example of a malthusian swerve that happened just in the last couple years and you know what there is one oil oh we're in the middle of the malthusian oil we are yes remember do you remember like in the 80s and 90s all of the talk about peak oil yeah do you remember yeah yeah yeah yeah yeah no and And even before that, like I think in the 70s and stuff, like it's like that we keep we keep having this conversation over and over again.

26:40Peak oil. Yes. Yeah, exactly. Yeah. You have you have people, you have geologists, distinguished geologists saying, warning us that, you know, we're going to run out of oil, that we're going to reach peak oil very soon. And that you just told you just said it in 52 years or whatever. Like you said, yeah, yeah. Same thing. Yeah. Yeah. Well, back in the 1990s, they were saying it's going to happen in the 2000s. They were saying, oh, crap, like we're going to start running out in the year like 2000 something. Yeah. And if you look at oil production, like, yeah, it does, especially in the U.S., yeah, it does kind of start to slow down in the 2000s.