Where is most of Earth's water?

00:00:08
Speaker 1: Katie, I've got an alien hypothetical for you. Okay, I'm i the alien in this hypothetical. No, you need the aliens in this scenario. Cool. I've always wanted to get drinks with aliens. So my question is, you're at the bar, you're sipping space martinis, whatever. How do you describe to aliens what Earth is like? Well, first of all, I would be sipping a cosmic cosmo, and I would describe Earth. Well. I'd want to be fair about Earth, but if I'm too nice about it, they might want to take it from us. So you know, I'd have to really walk the line between playing it up too much, making it sound too good, or making it sound too bad. Yeah, that's a delicate balance between honesty and like a species of self preservation. I guess I could tell them that it used to be amazing and gorgeous, but then we ruined it, and we're not going to get an invite to their planet. I mean, would you invite us depends on your cosmic cocktail recipe. Hi, I'm Daniel. I'm a party gold physicist and a professor at UC Irvine, and I would definitely not invite me to your alien planet. And I am Katie Golden. I'm stepping in for Jorgey. I host the podcast Creature Feature and the secret to the Cosmic Cosmo is just a little bit of sprite. What if you get to the alien planet and you want to make this famous cocktail the reason they've invited you across the light years, and they don't have sprite. I mean, I guess Dr PIB would do fine. Well, I'd be worried that if I got invited to that alien planet, I'd bring with me some crazy microbes that would like wipe out this alien species, and I'd be so desperate to learn from them and talk to them about the secrets of the universe, and then I would be the cause of their death. That's why it's always important to cover your mouth when you cough when you're on an alien planet or on a train. Right. I guess I'll just have to wear my mask or my has mat suit when I finally read Aliens. But that makes it quite difficult to drink a cocktail. It does, so I think if we are going to master interstellar flight, we may want to also master a mask that you can drink through. Well. Welcome to the podcast. Daniel and Jorge explain the universe in which we try to mix up a cosmic cocktail of craziness for you. The ingredients are all of the insanity in our universe, the crazy things that the universe does, from bending space and time to bizarre states of matter, to the squishiness of life on Earth and how it all works he losing radiance. We mix them all up with a healthy dose of silly jokes, and we serve it to you because we think that everybody deserves to understand the universe, or at least do share in our common ignorance and wonder at its majesty and at its crazy insanity. Curiosity, and also peach schnops are very important for the cocktail. Absolutely and horror. He can't make it today. So I'm very grateful to Katie for joining us today for an exploration of questions about the universe. Thanks very much, Katie. Yeah, I'm so happy we here, and I am excited to talk about I guess we're talking about some form of cocktail, aren't we. We are exactly today. We are exploring not the deep depths of black holes or what's going on in far away galaxies, but questions that are right here at home, questions that are literally under our feet, and questions that inform how we make our own cocktails. That's right. I really like when we talk about Earth because I am a little bit biased about Earth because I live on it, and I do like it. You're in the pro Earth camp. Yeah, yeah, it's very controversial. Take their Katie. I mean it kind of is, no, but you're right. It's important that we understand not just our origins here on Earth, but how things here on earthwork. From a practical point of view, we need to understand the systems that we are affecting, that we are influencing. When we say, oh, the oceans are basically infinite, it's okay to throw plastic in them. It's important that we understand the water cycle and how that actually works, and so questions about the nature of our home are very important as well as just feeding our curiosity for how everything came together to create the conditions that allow for us to exist. It feels so much like it was made for us. I love this quote from I think it was Douglas Adams, who wrote The Hitchhiker's Guide to the Galaxy series, who talked about how when you have a ditch in the road, the puddle of water that forms, and it thinks, Wow, how convenient that this ditch was made just for me, And maybe that's how we feel about the Earth. It was made just for us. In fact, we were made just for the Earth. But speaking of water, that is one of my favorite things about the planet Earth, how much water there is. As a living organism. I certainly enjoy that aspect to life on this planet. One of my favorite things about studies of the Earth is just how much those stories have changed over the years, how many mind blowing ideas we have unearthed in our studies. You know, the picture of how the Earth is formed shows that it's not just like a planet that's been zipping around the Sun for the last few billion years, but that there is crazy chaos involved. You know that there might have been a huge mar size impact or which helped to form the Moon. The Earth might have been very different early on, and really basic questions about what's going on inside it, how it's magnetic field works, and where all the stuff that made it came from. These questions are still unanswered, which means that there might be exciting discoveries still ahead. We might change dramatically our whole concept of like what the Earth is, just by asking pretty basic questions about what's in it and you put your finger on a juicy one literally, because one of the important features of Earth, of course, is it's water. I mean, if you looked at Earth from outer space, you would say, oh, the Earth is a water planet. We mostly walk around on the surface, so we think of like you know, the continents as the sort of main part of the Earth, but really if you look at it from space, it's mostly water. Yeah, And that's so interesting. We feel so our world is so restricted to the land because we are terrestrial organisms, but so much of life and so much of the world is in the water, which is particularly hard for us to study, as of course terrestrial creatures. We can't just dive in there with our bare, flimsy human bodies and air breathing lungs, and so it's this vast, vast area of mystery. But it's also full of life and physics and chemistry. So it's not just this void space right like where we have our land masses and just this blue nothingness in between them. It's full of stuff that is so interesting to explore. And discover and so much is left unknown about it, like you were saying earlier, and it's another lesson about how to avoid being biased by your point of view. We do this thing over and over as scientists, where we study like our little ditch, as you say, and we imagine we generalize from that that maybe everything is just like this, and then we discover, oh, our ditch is actually weird or unusual, you know, the way that we've learned recently that our kind of matter is very strange in the universe. It's a tiny fraction of the kinds of matter that are out there. You can't generalize from the way our particles work to the way the whole universe works. In that same way, we can't generalize from like how a life on the surface on the dry ground works to how life in general works. Is as you say, most of it's in the ocean, And so today we'll be exploring that question what is going on with the water on Earth? And more specifically, on today's podcast, we'll be asking the question where is most of Earth's water? If you look at it from space, of course you imagine, wow, it's mostly in the oceans. But is that the whole story. I am so interested to find out. It makes me feel like Earth is one big Easter egg and inside is maybe chocolate or maybe water. Yeah. Absolutely, And if you talk to geologists, it turns out that water is important not just for life and for cocktails, but also for important geological processes. It allows for volcanoes, or for mantle flow and plate tectonics. And there's a lot more going on inside the Earth than you might have a imagined. And that makes it sound like Earth is constantly moving under our feet. The Earth basically is a cosmic cocktail, and we are just finding out the recipe. So I was wondering how much people knew about the mysteries of Earth's water, where it came from, and where it is right now. So I went out into the Internet to ask our volunteers this question, where is most of the water on Earth? If you'd like to participate for a future episode, please don't be shy, right to me two questions at Daniel and Jorge dot com and I'll shoot you email instructions with how to play at home. But if you're listening at home today, before you hear these answers, ask yourself, where do you think most of the Earth's water is Here's what people had to say. Shouldn't you understood the question correctly? The most water on Earth, it's uh, we have it in in the oceans. Where is it from? That's fro a different salvage. I think most of the water is in liquid form, specifically the Pacific Ocean. Have a hard time believing there's more water, uh, in solid form in Antarctica or the North Pole, or in any form of water vapor in the air. My first case is the poles, the pole cats and the poles. And maybe it's a trick questions. I might say in the atmosphere, I'm pretty sure it's right around the area of the Mariana Trench. And do you think where it's deepest. I would probably have to say in the Earth's crust, because I know water seeps down in there. But I remember hearing at one point that it was a different consistency or different chemical structure, but still water. I'm gonna take a step at this and say it's not actually on Earth, it's actually in the Earth's crust. This is a tricky one. Of course, I would say the ocean, But then why would we be asking this question. So I'm guessing that it's trapped in like the atmosphere in particles, in particle form, I would assume it's in Antarctica, like in the polar ice caps. And that's why we're so worried about global warming, because the sea levels would rise in the temperature would rise as well. Um, So yeah, I'm gonna say it's in those giant mountains of ice, basically like a continent of frozen water. Most of the water in the in the in the on Earth should be in the Pacific Ocean because it's the biggest ocean, and also because you have like the Myra and Mariana Trench, which is like ten thousand, ten thousand meters deep. I believe most of the water on Earth are underground, somewhere in between the surface and the center of work. All the all the oceans are once we see most and we we have more access to they are just like a thing, a layer of our planet. They are really really tiny compared to the diameter of Earth. The obvious answer is the oceans, but that's probably too obvious. I'm guessing it's wrong if you're talking about freshwater. I did some work a while ago on modeling the glaciers in Antarctica and Greenland, so I'd say the ice sheets there have the largest amount of freshwater, and even more if you include the Arctic ice Cap and the rest of the glaciers around the world. I think the obvious answer is in the oceans, but I suspect that's not correct. I think most of the water on on our planet is in the crust, so it's in the plates of the crust, and maybe a little bit deeper as well, So I think that's where the vast majority waters um in the in area, not in the atmosphere or the oceans. All right, Katie, what do you think of these answers? I mean, that's really interesting, much more creative than my brain would go like, because I think, of course oceans, lots of water in the oceans. But yeah, I do like this idea that maybe there's some secret water tucked away deep inside the Earth, because when you think about it, you know, we can't there's so much of the planet at this point in our state of technology we cannot explore without being very much melted or crushed. Yeah, that's absolutely true. There are mysteries deep in the Earth. I really like that the listeners point out the variety of different kinds of water just here on the surface. Obviously you've got your oceans, but then there's water in the atmosphere. There's the polar ice caps, there's lakes and rivers. There's so many different kinds of water just here on the surface with us. And like how some folks were wondering, like how much water could be in the atmosphere, how much water could be in the polarized caps. Yeah, because water so versatile. It comes in a solid, a liquid, and a gas, so there's much more opportunity for it to exist than just in you know, the big old puddle of the ocean. And one of my favorite things about geology of water is that geologists talk about water in a crazy unit. They use a unit of oceans, Like how many oceans of water are we talking about? So one ocean of water is basically all the water on the surface of the Earth, And if you had like five oceans, that's like five times all the water on the surface. It's a crazy unit. I love when people invent insane units because they're just talking about vast quantities of stuff. You know, now, how many Olympic swimming pools. Would an ocean be some very big number, more cocktails than you could drink in an evening with aliens, that's for sure. I love of water. I like to drink it. Uh, it is good for my body to be alive. But has it all it seems so convenient for life. How did it even get here? How did we even get water on the planet Earth. It's a really fascinating question. It turns out to be a really important one to understand where the water is, is to figure out where it came from, how it formed with the Earth, or whether it formed with the Earth. So these are all really interesting, interconnected questions. And this sort of a standard story you hear in science and we've talked about on the podcast. It turns out to be a little bit more complex. Recent studies have sort of cracked open some questions about that. But the standard tale, the one we begin with, it goes all the way back to the origins of the Solar System, so you know, the Sun and the planets didn't exist throughout the whole history of the universe. The universe existed for like nine billion years before our Solar system came together, before our star even shined, which is sort of hard to imagine. Again, we think about like our little ditch as the most important place in the universe, But almost ten billion years went on before our ditch was even form. But our solar system came together from a huge cloud of gas and dust, and lots of those bits were left over from other stars that lived and then blew up and spread their materials out into the universe. We're kind of a recycled solar system. You know, at the end of the night, you take all the half drunk cocktails from the bar, you pour them all together, make a mix. That's basically our solar system. That is called a brain smash or not a cosmic cocktail. Well, you mix all that stuff together, and you know, you have a lot of hydrogen. Most of it is hydrogen because that's just what the universe started with after the Big Bang. But you have bits of oxygen and carbon and heavier stuff in their uranium from neutron star collisions, etcetera. And then something triggers a collapse. The cloud gets cold enough and maybe there's a super and over shock wave that comes by, and you start to get a gravitational elapse and things start to condense. Most of the stuff, of course, goes to the Sun. The hygrogen gets pulled in, and then you get the formations of this planetary disk, which becomes all of the planets. And again a lot of it goes to Jupiter, but some of it pulls together and forms like the inner rocky planets. But then it's fascinating because you get different compositions of stuff further out and closer into the Sun. Like closer into the Sun, of course it's warmer. You've got lots of solar radiation, so things like water, for example, can't exist in solid form in the inner Solar System. You've got like molecules of water. They get blown out to the outer Solar System because their vapor, whereas in the outer Solar System water can freeze so it can participate in like you know, gravitational accumulation. That's why you get like ice planets. Further out in the Solar System, you don't get ice planets like near Mercury and Venus. And it's so nice that we happened to be right in the middle there where we're not an ice planet, but we're also not just avoid of any water. Otherwise we couldn't be here yeah, that's true. Although we think that the young Earth was probably born dry because the conditions were not good for water to be liquid on the surface. It would just to get vaporized and then it would sort of float away and get blown out into the rest of the Solar System. And so they think that like, while there may have been water as part of the formation of the Earth, any of it that existed on the surface probably got blown away, got blasted clean very early on in the Solar System's history. So that is very different from the ocean filled planet that I know of in terms of like, you know, the early oceans just being these huge chaotic masses of water and chemicals with some land around. But how did we get from being just a dried out, desiccated planet to being one that is so full of these huge oceans. It's a question that people are still exploring. But one of the ideas is that after the chaos of the Earth's formation and the drying out actually of the Earth's surface and then the Moon forming collision, right where some huge object comes and smashes like vaporizes the entire crust and forms the Earth and the Moon, you know, oceans could never have survived any of that. But they think that after all of that initial chaos, water came back to the Earth. You know, the initial water that would have formed primordial oceans is gone, but that water was redelivered to the surface by icy messengers. And so sometimes people say it might be comets, because comets are basically snowballs, and you land enough comets on the surface of the Earth to basically fill an ocean. Some people think it might be more like asteroids, that asteroids have a lot of water in them as well, essentially the form of ice, and that these carbonaceous chondrites they're called might have the right mix of the special kind of water to basically replenish Earth with one ocean, like deliver an ocean of water to Earth. That's amazing. I love the idea that little baby Earth just got pummeled with enough snowballs that oceans started a form. It's crazy to imagine that you could deliver an entire ocean. I mean, the quantities of water in the ocean are just incredible. I live here in southern California. We go out to the beach all the time and it's just, oh my gosh, it's so much water. You know, and we can hardly see a tiny little slice of it. And you can sail for a thousand miles and remember flying once for an academic conference in Tahiti, which is quite a boondoggle, but you just spend like hours and hours flying over water which is like miles deep. It's really hard to imagine filling that up with snowballs. Like if your job was to throw snowballs at the Earth until you had an ocean's worth, it feels like you'd be there forever. And then when you look at some of these diagrams of like the deepest points of the ocean and how are you're just kind of stacking up statues of liberty. There's an immensity to it that's almost intimidating, exactly. And I think the way to reconcile that is to realize that that immensity is actually absolutely tiny on the scales that we're talking about. I mean, the ocean, you right, it's vast, it's deep, it's incredible. On the other hand, it's also a very very thin layer on top of the Earth. So like the ocean in terms of like fraction of the Earth's volume is paltry. You know, like if you were holding the Earth in your hand, it would like feel a little bit wet. The oceans just sit as a very thin layer on top of this massive Earth. And that's the clue, because there's so much material out there in the Solar System that if you smash a fairly large meteor or comet onto the Earth and its friends could easily contribute enough water to replenish this fairly thin ocean we have on our surface. So it's kind of a soggy marble rather than a water balloon. So is Earth is holding all this water because the water is pulled in by Earth's gravity? And is it protected at all from the universe? Like, why doesn't it just evaporate? It does actually still evaporate. Water is fairly light, and if it's in the upper atmosphere, it can get blown away by the Solar wind. And the Earth is constantly losing atmosphere to space all the time, and water is a big part of that. And so we are still losing some water and then we're getting some more water as things hit the upper atmosphere. It's not like the Earth is isolated from the rest of the Solar System. It's part of this whole complex network. Things are moving much slower than they did very early on. But you know where we are today is like a snapshot of a very slow moving process, sort of like when you think about the continents. You know, the continents, you don't think about the moving, but you know in your heart that in a million years and in a hundred million years, the surface of the Earth will look very different. I mean, if you live in California, you probably do think about the continent's moving, because it does happen. Yeah, exactly there this shaken and sometimes stirred, but you know, I love getting this glimpse as to these geological time scales that the Earth really is changing, the solar system really is changing, and that water itself is flowing around the Solar system from here to there. It's super fascinating and the way that they figured this stuff out is also really an incredible piece of detective work. Ah, the suspense is killing me. Well, I'll just drink a big glass of water while I wait. Let's take a quick break, and then we'll talk about how we figure out where water on Earth has come from. Okay, we're back and we're talking about Earth as a cocktail. It's got lots of nickel, and it's got a delicious drop of cosmic sprite. You left us on a cliffhanger about how we discovered where this water came from. And I have to know, I've been sweating buckets and I've been trying to replenish my water by drinking glasses of water. Just I guess kind of like, maybe is this, what is this? How we discovered it? People we're thinking about how maybe Earth got its water, and then they started sweating because they were thinking so much, and then drinking and wedding, and then came to them all of a sudden. I don't know that much about the personal history of those scientists, but the scientific history of it is quite interesting. It turns out that water is not the same everywhere. Mostly water has an oxygen and then two hydrogen's right H two O, and hydrogen is the most common element in the universe. It's just a proton with an electron around it, right, Well, that's the normal hydrogen, but there's another form of it. You can also add a neutron. So if your nucleus has a proton and a neutron in it, we call that deuterium. So it's exactly the same electric charge, and the properties of it are very very similar. But it's a little bit heavier than normal hydrogen. And so if you then form water with deuterium instead of hydrogen, you get something we call heavy water. And so it's got a normal hydrogen, one heavier hydrogen deuterium and then oxygen, and it has very similar properties to normal water. Okay, so if you're looking at a glass of deuterium water versus normal water, can you really visually or physical really tell a difference on a human level. That's a great question. Well, heavy water is like ten percent denser than normal water, so you might notice if you pick it up, you're like, this feels a little bit heavy. Suppose if you're like very sensitive to the contents of your cocktails, But otherwise it seems sort of normal. We use heavy water on Earth for various industrial things. Is it drinkable? Heavy water can't participate in biological functions in the same way, But if you drank it, it wouldn't be that big a deal because you have to replace like a very large fraction of your body's light water with heavy water before became toxic. So, like you know, accidental poisoning with heavy water is not something to worry about. If you, like are in a lab and there's a glass of heavy water and you accidentally drink it, you're not going to die. Okay, that's good, So drink heavy water responsibly. I wouldn't recommend drinking anything. I'm just saying if you just did, don't panic. So I'm assuming like you're not going to go out to a lake or a stream and just find, you know, spot of heavy water. Where would you find heavy water on earth? Or do you have to create it? Heavy water is everywhere. All the water on Earth has some heavy water in it. So it's less than like one part per mill of deuterium to hydrogen. So every glass of water you drink, as you know, it's less than like one thousands heavy water, but it's there. It's everywhere. I just spit out my water. You couldn't hear it, but I did do it. Well, you shouldn't reject it because you're also one part in the thousand's heavy water, like you have deuterium in you. Yeah, But one of the really interesting things is that this fraction how much heavy water there is how much deuterium there is changes depending on where you are in the Solar system. So like you can use this as sort of a fingerprint. If you get a glass of water, you can get a clue as to where it came from in the Solar system based on what fraction of it is heavy water. Wow, so can we tell where the Earth was hit by these visitors from the Solar system based on concentration of the heavy water. Well, most of the water on Earth has about all the same heavy water ratio, Like all the oceans have the same heavy water ratio. It's all mixed together. But what we can do is say, like, where else in the Solar system has this same heavy water ratio? And then we can say that's probably where the water came from. And it turns out that Earth's oceans have a higher fraction of heavy water than you would expect to have been formed in this region of the Solar system. It's more like the heavy water ratio as you find further out in the Solar system, like in the asteroid belt or in the ort Cloud where they think there was more deuterium early on. So we got our water imported from the or cloud. Yes, And so that was one of the clues that led to this idea that the water might have come from comets and from asteroids because those that they thought had this kind of heavy water. For a long time, people thought, oh, it's probably commets, because comets are snowballs and asteroids are are rockier. But remember on our recent podcast episode we talked about comets and how big they can get and how crazy they are, and you asked what we had learned by recently landing something on the surface of a comet. And that's actually relevant to today's podcast because when they did that, when they sent the Rosetta spacecraft up and they sent a lander down onto the surface of the comet, one of the things it did was measure the deteriorum fraction of the water in that commet, to ask like, is it the same as the heavy water fraction here on Earth or is it totally different? So what did we find. Are we getting our water from comets or from asteroids? Well, what they found is that one commet had a lot of heavy water on it, more than we have here on Earth, like a higher fraction. So then people, oh, maybe comets didn't contribute that much to Earth's water. Maybe it was more asteroids because asteroids that they've sampled have a heavy water fraction that's more similar to Earth. But the picture is sort of confusing because then they sampled from another comet and they found a fraction that is more similar to Earth. So the story is like, wow, those comments are a mixed bunches. You can't just say, like, all the comets in the cloud have one heavy water fraction, some of them have a lot, some of them don't have very much at all. It's really an evolving story right now. It's not something we understand very well. You can't judge a comment by a single surface lander, as the old A Dodge goes, Yeah, We'll remember, the Orc Cloud has trillions of objects in it, so you can't just like pick one and say this one is like all the rest of them. Right now, we've like sampled two of these things and we get two different pictures. That suggests that there's a lot of crazy stuff going on there in the Orc Cloud. So we got our water imported from the Orc Cloud, which it makes me feel like a fancy planet, like, yes, this is water imported from the Orc Cloud. If your career as a scientist doesn't work out, I think you should start marketing water as Orc water I imported from the Orc Cloud and make a killing that's even fancier than Fiji water. It's like, Wow, I've protet is from the Orc Cloud. That's awesome. And to be totally clear, I think the sort of leading scientific hypothesis right now is that comments did contruy me to the water on Earth, but not all of it, maybe ten to twenty percent, and people think the rest of it probably came from asteroids. There's this one really big asteroid Vesta, which is the largest in the Belt, and they found chunks of it on Earth like it's been involved in collisions and bits broke off and then fell to Earth, and they've cracked those open and found water inside them, like samples of water from other places in the Solar System that have agreed with the heavy water fraction here on Earth. So I think the leading theory right now is that comments played a role, but that asteroids probably brought the bulk of the water to Earth. But you know, it's an open question and it's evolving, and we may have a different picture in ten years. It is an actual water cocktail, which sounds very boring but actually seems very fascinating. We got this water now, and it seems like it's all on the surface, like we're, you know, a wet marble, not a water balloon. But is that really true, Like is there some hidden pockets of water somewhere that we don't know about. It's a great question, and it turns out that there might be water deep in the Earth. But first I thought it'd be fun to talk about where the water is on the surface, because a lot of our listeners were guessing it's like, maybe it's in the atmosphere, maybe it's in the polar ice caps. And some of these numbers, when I looked them up, they surprised me a little bit. I mean, of course, the surface of the Earth is water, and on the surface, of course, most of that is the oceans. So if you look at like the breakdown of where water is on Earth, seven percent of all the water on the surface of the Earth, so we're talking about like one unit of water one ocean of water on the surface of that is in the literal oceans, with almost half of all the surface water on Earth being in the Pacific, Like the Pacific is like half the budget all the surface water on Earth. It's incredible. I'd love to be at that board meeting of early Earth, like where should we allocate all this water? Exactly? It's like it's the biggest cocktail on the planet. And that's right. So already now you're talking about just three of the Earth. Water gets broken up into things like snow and glaciers. You know, like a percent and a half is snow and glaciers, and most of that is in Antarctica. Like Antarctica by itself is more than a percent of all the water on Earth. That's kind of incredible. Yeah, yeah, I mean it may not seem like a lot, but one point five percent of all of the water on the surface, that's a huge amount of water. And that reminds me of one of the listeners answers was thinking, maybe a lot of the water are in these ice caps because we're very concerned about them with global warming, But it really doesn't take that like proportionally, it doesn't take that much water to cause sea levels to rise. And so even if this is just one point five percent of the total water, that's huge, huge amounts of water. And the other missing one and a half percent and oceans percent and a half basically in Antarctica and other snow and glaciers. The missing percent and a half is groundwater. So that's water that's underground that we can tap and we can drink, and that's most of the water on Earth. But you notice we haven't talked about like the atmosphere and lakes and rivers, and that's because those are almost negligible. Like all the water and all the lakes on the surface of the Earth is point zero one percent of the surface water on the Earth. Almost nothing. And I mean I've seen lakes. It doesn't look like nothing to me from a human perspective. No, And I've lived in Chicago near Lake Michigan, which is amazing. Right in Lake Superior, they're vaft. If you're in the middle of them, it feels like you're on an ocean. I mean, there's waves and everything in storms, and you can capsize and you can die. And basically a puddle. That's zero point zero one percent of the water on Earth. So you should definitely take it seriously. And then as you keep going, like point zero zero one percent of the water on Earth is in the atmosphere and the form of vapor and clouds. It's just like the tiniest tiniest fraction. Do you feel vulnerable somehow? Yeah, it does. And then zero point zero zero zero zero one is in rivers, right, Rivers are basically irrelevant, though of course they play a vital role in you know, life on Earth and in salmon and all sorts of ecosystems. Yeah, you better not go around talking about how rivers are negligible to beavers, because they will they have sharp teeth, they're dangerous. And then something I was curious about is like what about the water in life? You know, there's all sorts of life in water, right, there's every sample of water you take, every cup of water has like zillions of microbes in it. But what fraction of water on Earth is in living systems? Right now? You know, all the elephants and all the whales and all the microbes add them all up together, and that's zero point zero zero zero zero zero eight per cent of the water on Earth. So you know, like that's basically negligible from the point of view of like how much water there is, But of course it's important to us, right, so you can't just weigh these things by their fractions. Obviously. That is so incredible, I mean, it really puts in perspective almost to me more importantly, not like how small we are, but how massively, massively huge the oceans are. It's just mind boggling. I told this number to my wife, who's a biologist, and she asked me, well, what fraction of water on Earth has ever been in life? Like which molecules have participated in you know, some microbe or some beaver somewhere. That has a great question. I don't know the answer, I imagine it's probably a large fraction, right, Probably every water molecule has gotten to be alive at some point. Yeah, that I mean, I often think about whether the water I'm drinking used to be dinosaur pp often really that's like a deal. Yeah, I mean, you know, if I'm I put the water through my bread of filter and I'm drinking it and thinking like, you know, I can purify this water. But chances are this was in some kind of dinosaur or maybe even in some kind of early human. You know, why don't you think about maybe it used to be in some early human cocktail caveman cocktail when he was like, you know, fermenting something in the back of the cave for a special celebration. With cave women partner. You know, maybe they were making early cave juice. I wonder if there's been any studies as how far back people have been making alcohol. I mean, I know that animals will imbibe alcohol when they come across fruit that is fermenting, so probably even our primate ancestors would imbibe alcohol. I would imagine we probably only started to make alcohol once we started agriculture, because that's when you could actually collect things like wheat and have the time to ferment it. But there there is a theory that fermentation was an important stage in our evolution because it can break down sugars into a very nutritious and fun uh form Alright, Well, probably most of the water on Earth has played a rule in somebody's cocktail or in somebody's biological function, and at some point in the same way that like we're all breathing in part of Julius Caesar's last breath. It's all a big part of the cycle, and it's all mixes together. And it turns out that the water on the surface of the Earth, it's only a part of the water cycle of the Earth, and some of it might not be on the Earth, but in the Earth. So let's take another break, and when we come back, we'll dive deeper into the Earth and understand whether or not there is more water than just what sits on the surface. All Right, we're back and we're talking about where is the water on the Earth. And we've talked about how most of the water that's on the surface is in the Pacific Ocean, and most of that probably came from distant parts of our learned neighborhood, the asteroids and the comets that delivered it after the young Earth had been dried out, and so that water in particular and sort of a larger heavy water fraction than you would expect from what would have formed in our neighborhood. But of course we can look deeper than just on the surface. We can drill down and ask like could there be water deeper down? Drilling for water it's a it's just you know, that's that's what you gotta do in Texas these days. And geologists have long known that there's water in the Earth's crust. Right, you drill down, you drink ground water, and we know that this water sort of very close to the surface, and that plays an important role in like vulcanism and play tectonics, you know, the way that the geology of how these things flow and what pressures and temperatures depends on how much water there is mixed in with them. Yeah, I mean you you also see with these deep sea geothermal events that are spewing, you know, these this hot, chemical filled water out at the events. So even though it seems that we've got all the water we need on the surface, there is this constant kind of chaotic activity coming from below the surface, right Yeah, And so for a long time people thought, well, maybe that was the whole story. You know, there's water on the surface and some of it gets like forced down deeper into the crust because of the crazy geology. But then people were wondering, like what about even deeper? And so to remind yourself, like what the sort of structure of the Earth is. We have this crust which sits on top of the mantle. The mantle is like rock that's not exactly liquid. It's under very very high pressure, and so it can sort of flow a little bit, and the crust is basically floating on top of this mantle, so the upper mantle, and then we have a mantle transition zone to the lower mantle. And the deeper you go, the higher the temperatures and the higher the pressures. Right, these things, every layer has more and more stuff on top of it. It's gonna be a little bit hard for people to imagine sometimes, like why is there's so much pressure in the center of the Earth or in the middle of the Earth. And you know, imagine like diving down in a swimming pool. You go really really far down in the deep end, your ears start to feel the pressure. That's because all all the layers of water that are now on top of you, gravity is pulling them down and squeezing on top of you. That's why I could go like really deep in the ocean. Your submarine could like implode, you could get crushed. So as you go deeper deeper into the Earth, there's greater and greater pressure, right, So and that pressure, that is that what is creating that heat. Yeah, that's what's creating that heat. Remember that temperature. A simple model for it is sort of like how fast the particles are moving. So you're like a box of gas. You measure it's temperature that tells you like how fast the particles are zipping around and if you then shrink that box, you're like pushing in on all of the walls. Then basically you're adding speed to those particles. Why you're adding speed is by pushing in on those sides. So if the particle is going to like bounce off the walls of that box, now the box instead of just being like a flat wall, it's like a train moving in towards the center. Bounce a tennis ball off of the train, it's going to come back at you faster. So you take a box of particles and you squeeze it with pressure, then you're speeding up all those particles, and that leads to the increased temperature. The same thing is happening inside the Earth. All these layers of stuff above you are squeezing down on you. That effectively heats up everything. So that's why the center of the Earth is hot. That plus a bunch of like radioactive decay that's still happening inside the Earth that provides more temperature to heat things up just offhandedly. Oh and also radioactive decay. But you know, I mean that reminds me of like if you've ever played ping pong ball and you have a paddle and you have the ping pong ball, as if you you're bouncing the ball on the table. As you bring the paddle down against the ball, the bouncing starts to increase in speed, in frequency. Exactly, it's exactly the same thing. The whole earth is basically a big ping pong paddle on all of these ping pong balls, and near the center it's very very high. You know, we're talking about like five thousand, six thousand degrees kelvin in the very core um and you know the transition region is like two thousand degrees kelvin, And so as you get closer towards the center, it gets hotter and hotter. So you have the mantle, and then you have a core, and you've got a bunch of layers. You've got upper mantle, mantle, transition zone, lower mantle, outer core, and then inner core. So you're like five major regions, and people have been setting like what kind of things form in those regions, Like when you have this very high pressure in these very high temperature and the sort of ingredients that we think make up the core, you know, the silicas and the nickel and the iron, what kind of things happen? And so in the upper mantle sort of like the layer just below the crust, it tends to form this mineral they call olivine, which is basically, under these temperatures and pressures, you take those ingredients to squeeze them together, you get this certain chemical structure that likes to form called olivine, which sounds to me like sort of like a tasty Italian snack, but they tell me it's not very good. I was gonna say that would be a very popular concept. And here in Italy if the center of the world was filled with olive oil, which is delicious, this does not sound so delicious. So so olivine is like this under high pressure material exactly. And the interesting thing about the structure of olivine is it really cannot hold water, Like the hydrogens and the oxygen's don't form as part of olivine like you form alivin. It like expels any water. So they think that probably the upper mantle is pretty dry. There might be some water in there, but it's like, you know, a hundred or two hundred parts per million. So you know, as they're asking these questions like where is the water on Earth, the first question to ask is like, could there be water. Do the temperatures and pressures and the things down there can they hold water? And so for the upper mantle the answer probably no. But fascinatingly, if you go deeper into the mantle transition region, then this olivine turns into something else. This becomes under the higher temperatures and the higher pressures, becomes something called wadsleyite. And I have no idea who's responsible for these names. They're totally bonkers. Could you just repeat that again. It's Wadsleyite, Wadsleyite, haads leite, which does not sound like something I would order on the menu of an Italian restaurant. You know, I'd be like, no, thank you. It sounds like it was discovered by someone named Wadsley and they were like, I'm going to call this wadsleyite. And you know, it's hard to imagine what these things are like. It's not like we're just heating something up on like you heat something up on your stove and it melts, you know. He we're talking about increasing the pressures of the temperatures too, really crazy amounts. You know, in a transition region, we're talking about like two thousand pounds per square inch of pressure. You take a rock and you squeeze it that much, it's going to cause it to flow. It's not necessarily melting. It's still technically a solid, but it's under such pressure that it can flow, it can be soft. It's sort of like hot unmelted wax. That is so hard to imagine something like rock in a liquid ish state. But it is not melted, and it's not a liquid. That's so weird. It's really weird. And one of the fascinating things about it is that this chemical structure is different from olivine, and it has little spaces in it, little like gaps where hydrogen and oxygen can slip in. So when they reproduce this stuff in the laboratory, they take like the same materials and they squeeze it down into crazy temperatures and pressures. They find that it can hold like one to three percent of its weight in water. You like take the ingredients and you squeeze them down, the water like disappears into the rock. It's crazy. It's like sort of like a sponge. Well, so it's like so those water molecules just get all integrated in with the rock, in with the rock, and so you have wadsleyite in this transition region, and if you go deeper into the lower mantle, it becomes something called ringwoodite, which you know, sounds like a condition and you definitely don't want to be died. But this stuff can also hold water, and so the transition to zone, this Wesley I could have like twenty thousand parts per million of water, and ringwoodite in the lower mantle can have like two thousand parts per million. But the lower mantle is huge, like the volume is enormous. So if you add up like all of the capacity of this, they think that the mantle could hold like five to ten oceans of water. Oh my god, that's incredible. So it would be absorbed into the Wadsley I or ringwoodite, and we wouldn't necessarily see this water. But if you wanted to like extract this water, would you squeeze it like a sponge or would you unsqueeze it like a reverse sponge? Exactly, you would unsqueeze it, And so this is something called dehydration melting. It's all sort of backwards because of the crazy pressures. But if slabs of this stuff come up, like float up through the mantle, closer to the surface with a pressure is lower, and then actually melt because of the weird chemistry. Sometimes you can melt something just by changing the pressure right without increasing the temperature. So as the pressure decreases that they melts and becomes a liquid and they produce water. So you take this rock, you like, unsqueeze it and it melts and produces water. Also, it's like water comes out of the rock when it melts. It's really crazy stuff that's really hard for me to get my mind around. So it's a reverse sponge where you unsqueeze it, you remove the pressure for the water to come out. Yeah, exactly, And you know, so far what we're talking about is like capacity for water. They've discovered that these materials that are in the mantle can have water. That doesn't necessarily mean that they do right, like a sponge could be dry. So then the second question is like, is there actually water in the mantle or is this just sort of like a capacity for water. So how would we I mean, can we even get that far down? I mean, if it's so hot and under so much pressure, how do we study the smith material Because it seems like any little obviously no human can go down there. But even if we had tools that could get that far down, how those tools even survive? How can we study this? Yeah, it's a great question, and you're right, and we can't just like drill down to the center of the earth and sample this stuff. But we do have a few ways to study this. So number one is just like proof of principle. In the laboratory. You can take these materials, you can squeeze them, you can get them the whold water, so you can prove like that this is possible. You can put them under pressure changes, you can see the water releasing. So they've been doing these studies, you know, please folks at like living more National labs confirming like that the chemistry is right. But then of course, how do you actually see that it's there. There's a few really cool ways to do it. We can't go down into the earth, but one thing we can do is let the earth spit up samples for us. So sometimes, for example, in a volcano, you'll get like little bits that come up from really really far down and have survived their journey. So for example, like sometimes volcanoes will spew up diamonds, diamonds that were formed very very far underground, sometimes hundreds of miles under the ground, you know, hundreds of kilometers under the ground. Diamonds were formed and in the heart of them can be like a little sample of the mantle. And because their diamond they will survive the journey up other little bits of the mantle. If they get spewed up from a volcano, you know, they change as they come up, but a diamond will preserve what's inside it. So they've actually found some of these diamonds, like down in Brazil, they went digging around and they found diamonds that have little bits of the mantle inside them, and some of them have this like ringwoodite, and they found water in them. So you can squeeze water from a diamond or from I guess unsqueeze it not from the diamond, but from the ringwoodite inside it. So that old I guess old ancients saying had some truth to it, except the opposite. So that's incredible. So it does have water. We know that not only can't store water, but it does have water in it. So what conclusions can we draw though from such a small sample. We can't draw that much from just a few diamonds that it's very exciting, you know, to concretely see like actual water come out of a rock from inside the earth. The better way to study it to draw larger conclusions is to try to do larger scale studies, and so we can sort of see inside the earth without actually going there, you know, one thing that we do to understand like all these structures of the Earth. You might wonder like, well, how do we know that there's mantle, and there's lower mental, and there's core. How do we even know about any of that. We know about that by sending sound waves through the earth. Every time there's an earthquake that shakes the earth, and those sound waves propagate through the earth. And every time sound hits a barrier, you know, like when sound hits glass or when sound it's water, it changes direction and some of it reflects. And so by listening to like the reflected sound, we can tell something about the densities and the transition regions and the sort of interfaces underground. So this is sort of like seismic studies to tell us about what's inside the earth. So we just set up a couple of speakers, put them against the ground, and play some a C D C and kind of listen for how it comes back up. How do we actually send out and receive sound waves. Do we kind of create a mechanical bat situation. We can't do that, unfortunately. We can't create sounds strong enough to penetrate the Earth with these studies, but the Earth generates it for us. You know, there's thousands of tiny earthquakes going on all the time, and these are great sources. We can do the same thing. For example, on Mars, they have a seismic listener on the surface of Mars now listening to Mars quakes to try to understand whether the core of Mars is solid or is liquid. We have a whole podcast episode about that. By very carefully listening to these essentially ringing of the earth like a bell due to these earthquakes, they can get a sense for what's going on underneath, and very specifically they listen for like what's going on in these transition regions. And so this ring would it if it has water in it, then it can sink. It makes a little bit heavier, and as it drops out of the transition zone, then the pressure comes in and some of the water comes out of it. Causing the mineral to melt because it doesn't have the water in it anymore. And then just below the transition zone where this mantle materials descending, these like pools of molten minerals form, So you get like different behavior at the transition regions between like the mantle and the core, the different parts of the mantle, as some of these things, if they have water in them, rise up through it and release water as they drop down through it. So all of this sort of activity at the transition regions can create these like pools of molten material and these will change how seismic waves propagate, so they can sort of tell if water is there because it changes how the seismic waves propagate, especially at these transition regions. And they've done these studies and they found what they think is like a massive ocean of water basically deep under North America. So we think there's a mass ocean of water because is I mean, from what you you described, it kind of almost sounds like a lava lamp where you have this material sort of melting and then unmelting and then dropping down. So we're measuring the water based on the pools of the molten material not, and assuming that because those exist, then the water must exist, right exactly, the water is necessary for these minerals to have these properties that create these sort of special layers that we can see with seismic bouncing. That's I know, and the picture is becoming clear and clear. They do these other really cool studies where they look at the electrical conductivity of the earth, right, like, how well does electricity propagate through the earth? You might imagine, like, well, how do you do that? You just like stick you know, a wire in one part of the Earth and then another one and see if you can, like you know, send electricity through it like your finger and shove it in the dirt. Exactly. But again we have really large sale questions. We can't generate those kinds of currents. But what we can do is look at the magnetic field of the Earth, which is generated we think by flowing currents of ionized particles deep inside the Earth and the magnetic field, of course, in the electric field are closely connected. You have this dynamo effect where the magnetic field pushes on these things and makes them to spin faster and creates an electric field which creates the magnetic field sort of self propagating. So by studying the details of the magnetic field, we can get a sense for how electrically conductive the earth is, and the presence of water in the mantle will change that conductivity. And again they see evidence for conductivity changes that are consistent with there being a lot of water underground. That's amazing. So so it seems like we do have a good amount of water underground. What does that mean? Does that mean that we're constantly surfing from our upper levels? I mean, I guess we are, because even without water, the lower layers are moving around and sort of like this unmelted wax situation. But what is next for this water? Are we going to try to drill down and import it for rich people to drink? It's a really cool question. One study I read recently found a spot in the Baffin Islands in Canada where sort of the mantle is much closer to the surface, where it's like actually maybe accessible. There's less crust and more mantle, and they found samples that have a lot less heavy water than the surface water. So what that suggests is that this ocean of water that makes up Us and the Pacific and the Lake superior and all that kind of stuff may have been like late arrivals from comets and asteroids, but the Earth may have had five to ten oceans of water inside it from when it formed, so like the true Earth water, the original Earth water is still deep underground somewhere, and it's not mixing very well. Like people don't think that the water that was in the Earth could have gotten there from asteroids and commets. There isn't time for it to like flow all the way down to the mantle, even in the billions of years. So it's almost like we have two separate water cycles, you know, the surface water and then the internal water, and the two haven't really mixed very much. If that's really interesting. It makes me wonder, do you know if there's any importance in terms of the fact that this water hasn't mixed with our surface water in terms of the chemical composition of Earth's water, Like what having you know, less heavy water change our oceans at all. I don't think having less heavy water would make much of a difference on like our biology or anything like that. It's really tiny, tiny fraction. It's more useful. It's like a fingerprint. It's I think most helpful for understanding like how do these planets form? Where is the water on them? It's also really useful for thinking about other solar systems. You know, we're looking at other planets out there and other solar systems and wondering like is there water on them? Now we can also be wondering like is there water in them? Some of the models I read suggested that, you know, while most of the water that was on the surface got vaporized, the water may have like clumped together with blobs of dust as the Earth was forming and protected itself sort of, and these primordial blobs of water then got like tucked deep into the earth. And we've talked so far about like what's in the mantle, but people wonder like it does the core also have water? You know, the core they think is iron and nickel, But for a long time there's been a question about whether there's anything else in there. We knew know that the core is a little bit less dense than we expect, Like if you imagine the core is just iron and nickel, it should be a little bit heavier than the core that we have. So now they're wondering, like maybe there's a bunch of water mixed in with the core. That's what's making it less dense. And one study irate suggested it might have up to eighty oceans of water. That's eight zero oceans of water mixed into the core. So you know, a tiny fraction of the surface water is us It turns out a tiny fraction of the water on Earth might be the surface like the Pacific could just be a drop in the oceans that are inside the Earth. That's incredible. And so no owing or suspecting that there may be a lot of water content, say in the core or at least in the lower mantle, does that change how we understand how geology works. It certainly is. It's affecting our ideas for how these layers form and what they can do because they have water in it. You know, this is early days. This is like a pretty basic question about what's in the Earth, like how much water is there that we're only beginning to probe. And so what it tells you is that, like we have very little understanding of what's going on inside our own planet. Very basic stuff is just now being investigated and probably there are future discoveries ahead, you know, about what's going on inside the Earth that will blow our geologists minds and send them all to the bar for more cosmic cocktails. And they didn't even need to send Bruce Willis in a giant drill to the center of the Earth. That's right exactly. And I love how we can sort of see inside the Earth using all of these clayer techniques. And maybe there are more ways to auty of this stuff that nobody has thought of it. Maybe somebody out there who's listening will invent a new way to probe inside the Earth, to X ray it, to give us a sense for like where that water is. Because I suspect that we're in for a lot more surprises. Yeah, I think tickling the Earth and see if it sneezes anything out of its volcanoes. All right, well, thanks everyone for coming along on this journey inside the Earth as we drink deep into the mysteries of the Earth's formation and it's current composition. And thanks Katie very much for joining us today and drinking deeply of the mysteries of the universe. Thanks for having me. And now I am only going to have water if I know it was imported from the art cloud. Very high maintenance and look out for our new fancy influencers supported bottles of Water Water Water. Thanks everyone for joining us. Tune in next time. Thank you're listening, and remember that. Daniel and Jorge Explain the Universe is a production of I Heart Radio. For more podcast for my heart Radio, visit the I Heart Radio Apple Apple Podcasts, or wherever you listen to your favorite shows.