 Everybody ready to go? Okay. I will gavel this session to order. Welcome everyone to the science circles continuing program of panel discussions. I just want to take a moment to point out that the science circle is a grant funded nonprofit organization. So we appreciate your sort of abiding by our code of conduct and apparel and so forth. So you know, don't be a troll, please. So we have with us today, Phil Youngblood, Vic and Mike Shaw, who is Charza, and Alex Hastings, who is eroticious. Can you correct that pronouncing for me? It's Akkaranta Sukas. Akkaranta Sukas. Okay, thank you. It's a fossil crocodile that I named. Fantastic. I think we're all familiar with Phil and Mike. They've participated in a bunch of panels with us. So I want to especially acknowledge Alex being with us today. Alex is a published paleontologist. He's currently the Fitzpatrick chair of paleontology at the Science Museum of Minnesota and has held a number of other sort of curatorial and postdoctoral positions in paleontology. He has interests in the evolutionary relation to temperature and body sizing in ectotherms and factors influence turnover and extinction fossil predators. So it's a real honor and a pleasure to have Alex here. And there is a reason he's here. For today, we're going to talk about extinction. Modern extinctions. Many may be aware that there's an emerging consensus that we are in the midst of the sixth great extinction, sometimes also called the Holocene extinction. So today, I hope we can kind of unpack that idea in some detail because the story has more wrinkles than you might think. So I originally kind of thought of this idea because I kept hearing news stories about various types of animals becoming populations declining, insects, birds, corals. You just kind of hear these stories from time to time all the time now and it is a little bit alarming. And I had originally thought that, well, maybe we could look at some specific instances of population declines in specific species. But the more I looked into the topic, once again, I kind of changed my focus. And I really just kind of think it would be worthwhile to just kind of explore what extinction means and why we think that we may be in the midst of a new great extinction. And just, it turns out to be have, like I say, just seems that the whole story seems to have a little more wrinkles than you might expect. So I'm hoping we can kind of dig into it. And with that introduction, let me introduce Alex and let him make some an initial presentation regarding his thoughts on the subject. So Alex, take it away. Great. Thanks. So this is just a kind of brief little overview of kind of extinctions in the past, kind of leading into the extinctions that we're seeing now. So we've got Sean is in charge of slides here. So if you can advance the slide, kind of dodo to set the tone here a bit. Perfect. Thanks. So the big thing kind of looking into the past course, there have been many, many, many, many extinctions going back throughout the hundreds of millions of years or billions of years really of life. But we generally consider there to have been fit five big mass extinctions in the past. So when we're looking at the chart here there's these five call outs the end or division and Devonian and Permian and Triassic and then usually when we think of a big extinction in the past we're usually thinking about the end Cretaceous, which was the end of the age of the dinosaurs at about 66 million years ago. But there have been certainly other large extinction events in the past. In fact, the largest of which was the end Permian extinction that really, really tall spike in the middle. And that was the extinction that was right before the end of the age of the dinosaurs what kind of began the next age. And when we're kind of breaking up these big chunks of time. We often use these mass extinction events as markers for how we divide chunks of time. And by the age of dinosaurs is bracketed by two major extinction events and then kind of some of the subdivisions is also one of them is bracketed by the and Triassic extinction. These are times we have massive changeovers in the kinds of life that we see across earth on one end of the extinction versus other. And this is one of many reasons why we're currently looking at defining a new era, the Anthropocene or the human era, because we're going through kind of by a lot of measures a mass extinction event right now. There's also other things that we're doing that are affecting our worlds. This is kind of the idea behind defining a new era. Now when you talk to paleontologists often, we kind of view extinction in a little bit of a different light because it is a natural process. So the fact that their extinctions happening right now is not surprising you would actually expect that it really comes down to the rate of extinction and it also comes down to the cause of that rate increase, which will be getting into a little bit more here and then I'm assuming as we But these big extinction events are often kind of defining time or at least how we define it. Can we go to the next slide or loading a bit or at least on my end we're still. So we'll give that a second. What is it? I'll read some questions here. Oh what so question was what is the threshold that defines extinction. Really an extinction is just kind of the the absence of species now when you get into modern extinctions it kind of gets a little bit hazier because we're In the past it's just literally not finding any more of the things so like you have a species of a trilobite in one place, and then it just disappears. So we're talking about modern extinctions it's often the last individual dying out so there's no living representatives. But things like hybridizing can start, you know, bringing up some questions so if you know it's not the quote your genetics but it's still kind of some, you know, genetic information then it kind of starts to get hazy and then you Really have de extinction where things die all living representatives died out but then you clone a representative so then that extinct so it gets into some really weird gray area and then as Benny just brought in what is a species gets a little hazy there too. So as we'll kind of be discussing here today there's not everything is clearly well defined with nice bracketed ends on either side. The diet is totally not. Oh, there we go. Okay. Finally loaded for me. Hopefully others can see it basically it's just a concept picture, which reinforces the idea that when we're looking into the past we're really only seeing a piece of the overall picture of extinction. So when you think about the way that things fossilize. We're looking at kind of a whole ecosystem and typically things that have hard parts or what are actually fossilizing. So things that have bones, especially large things that have bones like dinosaurs or crocodiles and turtles have a much better chance of fossilizing. So if you think about all the tiny little things all the insects all the slugs the amoebas really have very very little chance of even becoming a fossil and then being able to actually recognize what those things were and the diversity of them and how they went extinct. And when we're looking into the past we're really just getting a biased glimpse of the past now relatively speaking we can say well a lot of the things that we are finding are going extinct at this time so regardless we are looking at a massive change over things but it could actually be far worse than what we're seeing. And especially when we start to consider something like the number of species that are alive today, which is also really hard to get a handle on we're at over a million of just named species of things. But when you start trying to factor in the kinds of things that we don't know that are even alive today, it's potentially even getting into over 8 million species alive today. That's one geologic moment in time if we go back in time, we're looking at quite likely billions and billions of species going into the fossil record far far far more than we've actually been able to recognize. And so it's this problem where extinction is, we're losing things that we don't even know we have. And that's true, not only for the past but even for our modern ecosystem. So can we go to the next slide. And I'll catch up on some. Oh, that one loaded real quick. So there have been some attempts to try and put some numbers on extinction rates right now. So this neat study in 2015 basically used the IUCN. I should have looked up it stands it's a conservation network that basically keeps track of the endangered and threatened species across the world today. Now this has very strict guidelines behind what actually counts as extinction. So when you look at this graph you're actually looking at a highly conservative estimate of the rates of extinction here. And we're looking at based on the bottom is more or less historical records so since we're able to start keeping track of that. And if you look at the bottom there there's a dotted line that says background, that is the rate at which we would naturally expect things to go extinct. Because things come and go that's a normal thing. What we're looking at is basically no matter how you break down the records and these are pretty biased towards vertebrates. The rates are increasing rapidly as we go towards the more modern era. This is under kind of the most conservative ways that we can possibly put this together. We're still looking at rates of extinction that are much, much higher than we would expect as background rates of extinction. And those rates are rapidly increasing it towards the modern era. So that means that even by the most conservative versions that we can find those extinction rates are far exceeding what we would naturally expect. That's a good indicator that you're going into a mass extinction event and not just normal kind of ups and downs you would normally get. Also is a pretty good correlation towards kind of the effects that humans are having on their environments and giving you kind of better support for us defining a new geologic era based on the kinds of things that were to our environments and to these things. So it's putting into real terms and putting some numbers on something that we're also seeing quite. So it's often typical to kind of think of the big elephants and stuff like that and okay we still have elephants we still have cheetahs even though they're rare. But there's a lot of other things that we're you know maybe less familiar with that are dying out. This is kind of feel. Can we go to the next slide? So Lonesome George. Lonesome George is a good example of modern extinctions now. George was a Galapagos tortoise. He lived specifically on the island of Pinta and he was the last known representative of a subspecies of the Galapagos tortoise. And the reason why we can say that pretty darn confidently as they made a massive effort is really just one island that was known from and they basically combed the whole thing and a massive survey got people climbing over every square inch of that island and did not find any other tortoises. They did find a few bones of one and that was. So they relocated Lonesome George to a wildlife preserve on another island in the Galapagos where he lived out the rest of his days and they made strong very very strong efforts to try and get him to successfully breed with any female Galapagos tortoise. Realizing that you know any children would be hybrids but trying to conserve some of his genetic information. Ultimately those efforts failed. They did collect genetic information from George so he could be cloned. He did live over 100 years old so that's pretty darn good and he lived out the end of his life quite comfortably and he was taxidermied so you can still go and see him on display in on the big reserve on Santa Cruz and the Galapagos. So perhaps his genetic information will still live on in the future. But this is a case where we're able to really document the very very end of a species and by most definitions that subspecies is now quite extinct. Then potentially could bring it back and then through cloning and then that becomes a little bit more hazy again whether constitutes extinction. But there are a few cases in modern systems in which we can really document exactly very very end. There's a similar scenario for the Tasmanian tiger and the passenger pigeon and the quagga which are all animals that died out within human time. And the last known representative died within activities so we know exactly what happened. There's of course many other examples in which these wild some definitions where if they die out in the wild they're already considered extinct. But then if you bring them back into the wild does that make it non extinct. It's a lot of gray air. And we go to the next slide and I'll read some read up here. It is incredibly sad. There was a reason why George was called lonesome George in the end or Solitario Jorge. So this is a vulnerability map that was done just a couple of years ago showing basically kind of when you're trying to conserve not just a single species but you're trying to conserve ecosystems. This is a far better way to try and conserve species on the whole. So if you imagine trying to just save the elephant which is great we should save elephants. But a much better way to save the elephant is to save the habitat that it lives in and then by proxy you're saving a lot of the other animals in its environment some of which you may not even know exists there. So that also gives the elephant a much better chance of moving on and propagating and being successful by giving it all the cohabitants that it needs in order to survive. So this is kind of the kind of perhaps more effective way of conserving species in the futures by going to these areas of high vulnerability and these are areas that are typically quite species rich. The darkest colors in terrestrial ecosystems are the Amazon and Central Africa and Southeast Asia to the places where we have the most species just in general, as well as the darkest blues in the tropical areas of the Caribbean and Southeast Asia again. So these are areas that are at highest risk, as well as maybe a bit more surprisingly into kind of more temperate landscapes across Central Asia and into Europe. Now a lot of this is from habitat degradation as well as climate change. So this is where we're anticipating the greatest need for conservation based on changes happening to. Of course those are not exclusive areas, huge areas of North America and in other parts of South America, Africa basically the world over has areas that are quite at risk as well and we shouldn't necessarily ignore those. That's probably where there are the greatest vulnerability and that's probably where it just can serve as much species and as many as much ecosystems that's where it could be most common. I think I had one more slide. Can we advance that? Nope, that was it. So that's kind of a little bit of a depressing overview. Extinction is not the most uplifting topic. Hopefully we'll hit some hopeful notes in there that make it a little less depressing, but so I'll turn this over to, I think, was it Mike had a few slides as well. Yeah, before we move on to, I think, I think actually was Phil or slash Vic was going to go next. And but Alex, I wanted to follow up on one of your slides that suggested or indicated that mass extinctions are associated with geological eras. What I'm thinking about I saw when I was sort of preparing for today I saw a chart showing sort of the shrinkage in the in the ranges of like certain animals for example one that stuck at stuck out of me was the shrinkage of the range of lions in Africa, which at one time roamed huge swaths of the continent. But but now their ranges have have shrunk down basically what looked like basically sort of national parks in various African countries. And so that seems to be due to habitat loss and deforestation and so forth, the sort of turning over a lot of the land into farmland for example and things like that. And then of course there is also climate change. So my question is, is so assuming we are in the midst of a new mass extinction. Is it such that we would predict it would be reflected in the in the geological record is there sort of what kind of what what do you what. How would it be reflected in the geological area to kind of conform with the idea that mass extinctions are correlated with geological eras. That makes sense. Yeah, yeah, no. And it's one of those that's kind of one of the whole issues with defining the Anthropocene is that these are usually defined on geologic boundaries which geology is a slow process. So the idea is that you would find as fossils, a large change over in the kinds of animals from one side of the boundary to the other. So that you would go from potentially a very species rich fossil record with bones and other remains of creatures across the board. And then a lot of those lineages dying out, more or less simultaneously when I say simultaneous I mean on a geologic scale. So something even over the course of 1000 or 10,000 years is still more or less considered the same time. Yeah, and that's certainly within kind of, you know, a lot of the historical extinctions are well within that timeframe. So the idea is that you would have less things going into the pipeline to become fossils. So you would see a lot of things dying out and I think a lot of the expectation is that that would be well documented but it's something that wouldn't really be able to be compared to past extinctions until that geologic process can take its time, which, you know, could take 1000 years and by which time all of us talking right now would be dead. So it's hard to really define while you're going through it when you're talking about geologic systems. But the idea is that that should carry through in a very, very similar way in the form of those fossils not showing up as we go into the Anthropocene because those lines have gone. Yeah, you know, one also preparing today what an example that kind of stuck out at me about how these things can be reflected in the rock layers is as the Earth's as the atmospheric CO2 has fluctuated throughout the Earth's history. There have been periods where, you know, a lot of CO2 in the atmosphere which acidifies the oceans, which makes it hard for shelled creatures to make shells, so they go extinct. And those periods are reflected by dark layers because, you know, there aren't any shelled animals. And then as the CO2 drops again, shelled creatures reappear, and those periods are reflected in layers that are white because they're full of shells. So that's just kind of another kind of an example of how of how the this history is recorded in the rock layers. Great. And ocean acidification, which is something we are facing currently as we're basically it's all carbon driven is was one of the the major factors thought to be the major factor in the largest extinction of all time the one that ended the era before the age of the dynamic. Yeah, so it can absolutely be a mass extinction driver. Fascinating. Okay, well, thank you very much. That was a really, really good presentation. And, Vic, why don't you take over and give us your thoughts. Sure. Okay, first thing is I'm not an expert. I'm a concerned scientist. Okay. I like to study lots of different things. So it's nice to hear from people that actually do it for a living. There's some thoughts on the slides up there. There's some thoughts that kind of cover some of the areas that we've talked about a little bit is one is kind of definition. So here again, since I'm not an expert, I like I love to hear the audience talk about things so that they can correct anything I say or agree or disagree or whatever that sort of thing. Yeah, citizen scientists right world, world citizen scientists so under definition I was thinking. Technically extinction means like there's no more. Okay, species is gone but when you say what about in the wild. In other words, we have several species. Now that basically there are more in zoos in captivity or than there are in the wild. So you could say extinction in the wild, which in zoos and such like that they you're not going to have a very diverse gene pool either. So the idea is that once you get to a point where the gene pool is so low, you also risk in other words you also risk extinction and you also risk higher vulnerability. There are humans if you actually study it a bit. There's a lot of studies that say that humans got down to only 200,000 individuals in Africa during a big change in climate. Some time ago and that's basically everybody on earth is related to those 200,000 humans that's why we can trace the mutations and such through the world for people that did those things. So why distinctions occur? Well, as I'm not going to read the slides up there, but I'm just going to talk a little bit about it, but why does extinction, why does extinction occur? Well, basically failure to adapt for, yeah, colocanth. Okay, that's actually one of the things I was going to mention is sometimes we think things are extinct, but they may just be on islands or in the case of the colocanth they were found off of eastern Madagascar someplace, but there again they're probably fairly vulnerable as far as the species. So failure to adapt. Now in some cases failure to adapt, remember that there were like 5 billion passenger pigeons. If I've got the right ones, passenger pigeons about 100 years ago and they were all killed by hunters and other people in the United States even though they were quite numerous, killed within a fairly short period of time. So failure to adapt, certainly an asteroid is not something you can adapt to quickly or hunting or habitat loss is difficult. So the big thing is, as the slide showed earlier, is at what rate would we expect changes, speciation stuff to occur. And in this case there are a lot of plants, animals of all kinds, which are not adapting well to the changes, whether the changes are climate changes, lots of habitat changes, acidic ocean conditions, all of that. So it'd be very interesting to see that. So that's kind of why we're saying that there is a recent extinction because there are a lot of animals which populations. Interestingly enough, I was at a real, not real, sorry, this is as real as it gets, but I was at a first life class just in between the events this morning talking about bird population. And one of the things they mentioned was that in the case of grassland birds, for example, the population is 50% lower than it was in 1970s. It was or in the cases of other birds anywhere from 30% to 50%. So bird populations have gone down tremendously. I'll show you a couple slides here in a minute. Let me continue with some of the ideas on this one. First of all, remember that extinction is a natural process. I mean, that's partly what evolution is all about is to try to adapt to different niches and changes and such. And that everything is going to go extinct, including humans one day, a little faster than we want to if we don't watch it. Running out of chicken, not sure. But see, that was part of the problem with the Dodo, of course, is that they didn't have chicken on Mauritius. And so the Dodo's were big flightless birds that were easily preyed on. And same thing with a lot of the flightless birds on islands in the world. I don't know, probably tasted like chicken. Okay. So in any case, species typically may last about 10 million years, although we know for a fact that there are species that are hundreds of millions, if not a billion years old that haven't changed very much at all, including the arid, the crocodiles, okay, and other species that haven't changed a lot. So there, yeah, island biogeography is very interesting about how the animals adapt to islands by becoming smaller and such like that. So in any case, in order in order to because there's not a lot of food and other sources. One of the things by recent extinctions is that we can, whether you like it or not, we can trace a lot of them to human cause with 7.7 billion people in the world with technology. We can wreak havoc on habitats so we can build freeways, we can take out trees, we can change the climate and that sort of thing. So we really are changing what would normally occur by way of natural extinction or evolution. So why should we care? I mean, okay, we can easily live in Antarctica or we can live in the tropics. In other words, humans, it's going to take a while for us to die out unless we kind of do things to ourselves. But why should we care? Well, partly because can somebody tell me what that game is? I've been trying to think about that all morning. The one where you stack stuff up and then you have to take the blocks out or you have to take little pieces out. Anybody remember what that game is? Yeah, that one. Okay, my grandkids love it. And we were playing it, well, Tetris also. But on the Jenga game, essentially you pull out little blocks. And the objective is to keep pulling out blocks until the whole thing collapses. And that's part of the problem. It's like, okay, maybe there's some frog in a pond in Death Valley or something. But it's not just the frog in the pond in the Death Valley, it's the whole ecosystem. Something eats that frog or the frog eats something and you're going to change the conditions of the ecosystem. And then you're going to have a domino effect to where it's going to change things to where it's noticeable. The other thing I wonder about is the do we care more about the species that we like? In other words, if the tiger dies, we're going to be very distressed. But what about the little frog in the pond in the whatever? In other words, which one has the greater impact on the world? Let me show you a couple of the slides that I have here. Yeah, mosquitoes, for example. In other words, a lot of people go, yay, let's get rid of mosquitoes, but mosquitoes have an ecological niche. Now here's another slide of the extinction of dense and I looked it up as to what kinds of things happen. And you'll notice that there's quite a few things happening in the early part of the Earth because the Earth was changing a lot. I mean, at one time we didn't have any oxygen. So there were extinction events long ago until the anaerobic organisms came into being. And then there was snowball and then there were lots of other... In other words, the world's life was a bit fragile back in the old days. And so you can see a little bit of some of those mass extinctions. Now notice that the blue is everywhere. In other words, there are extinctions that happen all the time. It's just not quite as many, quite as much percent. And then again, for example, with the dinosaurs, you've got things that were smaller than 5 kilograms on Earth actually survived. So you had birds survived. You had mammals survived. It was just the really large creatures who could not last that nuclear winter, so to speak, when the asteroid hit. And also, on a lot of these extinctions, it's not one event. I once had, when I was in the military, one of my jobs was as investigating accidents. And invariably, it's not one event. In fact, somebody mentioned it earlier that one of the issues of some of these extinctions, like I think the Dodo, somebody mentioned, is that there were also things happening on that island at the time. So in other words, you have very fragile ecosystems where lots happening. It may be, in the case of, if you look at the extinctions up there, it may be vast lava fields. Changes due to tectonic forces, like the Deccan Plateau thing, I believe, in India. And also in the Siberian areas where you have huge lava fields changing the composition in the air. Sometimes you have asteroids, they do come. And then, of course, we're bombarded by particles every day, tons of particles in the upper atmosphere. We don't usually have the really large ones hit except for every once in a while. And somebody mentioned perturbations in their orbit due to the Oort cloud and other things. And then, of course, global cooling and warming and things. Sometimes people, yeah, exactly the volcanism and stuff. So basically, a lot of people, sometimes people who don't want to face the idea of extinctions or the idea that humans are involved. Yes, we are. Okay. We'll say, well, you know, there were times of the Earth's history where there was more carbon dioxide or more of this. Well, I got to tell you, I don't want to go back to Snowball Earth. I don't want to have all the species we recognize disappear. And I don't want to live in the swamps of the dinosaur ages. The other thing is, as we, no one showed the population. Did somebody show population? No, I think that was the other class that was actually the first life class. Whatever they're showing population of humans is we are in a very tenuous speaking of tenuous situations as we continue to grow in population in the Earth. We're becoming in a more tenuous situation ourselves. Part of it is because a lot of people live right within a meter of sea level. Part of it is because with climate change, we're getting changes in the availability of water. We're getting changes in climate and that is more difficult to support. More difficult to support the types of crops. In fact, there was kind of a study that said that the middle of the United States, it won't be long within the next century that the conditions will be not right for a lot of the bread and basket of the United States. And that it will basically go up to Canada. And so basically Canada will become, or can, will have the same sorts of conditions that we have now in the middle of the United States. And maybe they'll become more of a bread and basket. Okay, so that's something to think about there. The next one that I'm going to show you here was actually a slide that I had in a presentation this morning. And it has to do with the natural cycles of plants and animals. And this has to do a bit with the ecological side of this. So let's take a look. I learned a new word. It's a phenology. Phenology is basically the study of life cycles that are influenced by seasonal and annual variations in climate. And what, let's take a look at how this might happen. So for example, I hope not tagline, frankly, I hope they become extinct. But that's my own opinion is. So here's how it can happen is birds have evolved over time period to take their migratory. They don't just go, okay, let's go south for the winter and because we want to go down to Rio and then come back up here, that kind of stuff. They have evolved over years to go along migratory routes and to stay in places where there's an abundance of food. And then they come back when there is a, it basically coincides with the peak availability of food sources. Okay. And so what's happening is that as things get warmer in the northern latitudes is plants grow up earlier and then they get their nice young leaves early and insects don't have as hard a time. And so they come out earlier. They eat the young leaves. They become whatever they become because insects have their own life cycles, you know, butterflies flying around, and then boss, that sort of thing. And so the birds go arrive late, kind of like, you know, flying in general where you arrive late. But in case birds come back to where they hope that there's a lot of food and then they find, oh, my, we're a little late. You know, plants are already out, plants have been eaten. The insects are, yeah, birds may have lost their luggage or just, they're all flying in mass. And so, you know, you get delayed on the tarmac and that kind of stuff. Okay. So in any case, so in any case, the birds come back. There isn't as much food sources as they were expecting. And so the poor little baby birds don't have as much food as they need to. Some of them starve. And so the populations of the bird populations go down. Well, by how much? Well, let's take a look at this. We may not like insects as much as we like tigers or little baby birds. But this is a slide of the insect decline. And so once you start having the base part of, in other words, like in the oceans, when you start having sick conditions, now you have animals that have calcium shells. You know, it's not just the reef. It's the diatoms and others that you're going to have less of. Well, they're the chain. Everybody eats them. So at least at the bottom of the food chain. So now you have the same problem that the birds have where there's not the food to support the population. And then you have those go down. And so it just ripples all the way up to the top of the food chain, which is us. You see the thing with the caddis flies, butterflies, beetles, bees, et cetera, going down. A lot of those are food sources for higher parts of the population. So why should we care about insects? Well, I added a few things to this slide here is one, their major food source. Okay. The other thing is they do things for us that we may not always recognize such as pollinate plants. They prey on pests. They break down dead plants and animals and done. They aerate and fertilize the soil. So without insects, there probably wouldn't be the plants that we eat. Or if they're in the plants, we eat and there aren't humans. Okay. So that's one of the issues. Now you go up a little further on the food chain and you got the birds. We've already mentioned something about birds decreasing. This is part of the issue right here is that part of it has to do with loss of habitat, which by the way, hey, how did that happen? Well, part of it's us, part of it's climate change, that sort of thing. And it's increasing. As I mentioned, anything from 30 to 50% of bird population since 1970 have decreased. Back a long time ago, I used to hear a lot more birds. And there were a lot more insects hitting my windshield than there are today. And it's not just because I'm getting old and I can't hear the birds. It's real. Okay. And so why should we care about birds? Well, almost the same reason is we care about the insects. Birds eat the insects that are harmful to us. Birds help pollinate plants. Birds disperse seeds. Well, remember, extinction is kind of like statistics. Extinction is the larger picture. I mean, for, you know, death is 100% certain for all individuals, but death of a species is extinction. So birds disperse seeds. And there are a lot of trees and other plants that count on birds to basically poop out the seeds and make sure that they continue to grow with a little bit of fertilizer. Okay. And birds eat animal pests. They eat dead animals. They are aesthetically pleasing to us. Yeah. All of that with all of the changes and the types of things we do that you might not even expect. And let me see if I have one other slide. Oh, that's the, that's the one that I did this morning and that you can see again later. So I'll take that copy out quick. Okay. All right. Fantastic. That was very helpful. Before we move along to Mike, I wanted to inject an additional thought just to kind of push back on this idea a little bit before we get too worked up. And I was particularly struck by your Jenga analogy because there is a school of thought that thinks that this notion that we are in the midst of a new great extinction is hysterical and that we, that it's not that bad. And the, the, I think it's kind of a two pronged argument. One is that it fails to recognize the true scale of previous mass extinctions and how cataclysmic they really were. They were, you know, a complete, you know, a practically complete loss of life on earth. And I think especially the, well, I forget the terms and so forth. So they are really absolutely catastrophic. And the idea is that they are the result. These great mass extinctions are the result of essentially a network failure. And so, so to understand this, you have to understand sort of the theory behind networks. And the idea is that once a network collapses, there is nothing you can do about it. And the analogy is that once the Jenga tower begins to fall, right, there's nothing you can do. You can't go back and start inserting bricks into the tower to reconstitute it. It simply collapses automatically. And there's no intervention possible. So the idea is that if we are, in fact, in the midst of another great mass extinction, it's too late to do anything. The network has collapsed. So, and I think there is some controversy about really where are we? Are we, is the network collapsed? And there's nothing we can do. It's just going to play out before our very eyes. Or are we, is it still early enough to have some useful interventions? And then finally, I just also want to make the point that there are some people who believe that this new mass extinction has been going on for a long time, like maybe as early as the Middle Ages for like 500 years. Because these things happen over geological time periods. And it's possible that human activities are accelerating the phenomenon during the Anthropocene age. But I should say, I guess, the result of industrialization and conversion of forest to farmland and all of that sort of stuff may be accelerating it, but did not start it. That it started earlier on also. And I guess I'm not quite sure what the factors are, because I'm not sure how much human influence was, how much the, how much pre-industrial human activity could account for that. So it may have started really without much human, without much being attributed to human activities. But then humans just poured gasoline on the fire, so to speak. So I just wanted to make those points before we move on and hopefully we can kind of hash that out a little bit about what, you know, has the network collapsed or is it only about to collapse. And with that, I'm going to turn it over to Mike and let him throw in his two cents on all this. Wow, the network collapse. Okay, this is a fun note to end on. And I think I'm going to pick it up and go with it. And talking about network collapse. So everything we know about the extinctions comes from the geological record. And we can read the geological record in many ways. We can look at the fossil record and the orders of the fossils in the rocks. And presumably rocks found deeper down are older than rocks that are found on top. Of course, if there's mountain building and the like, there may be some flipping of orders. But generally there's an agreed on order in which different species show up in the fossil record. And that gives us very good relative dates, you know, basically from different places on the planet. If you see the same sorts of fossils, you can generally think that the rocks are the same ages. We can also do better than relative ages. We can do various dating-type analyses. And dating rocks is actually very interesting. Radioactive dating is wonderful. It's not carbon-14 dating. Some of you may be familiar with C14 dating. C14 doesn't live long enough for us to really go back into the geological record. It's really good to about 70,000 years or something. Things like potassium argon dating, where radioactive potassium turns into argon. I think it's potassium 40. Looking at how various types of uranium, uranium 238 has half-life of a couple of billion years. Now it turns into lead. Basically looking at these traces of elements in rock samples can give us a good idea of their absolute ages. So what the comment I'm trying to boil the stem to is that we know a lot of things about biodiversity from the fossil record. We may not be able to see every single life form that has ever existed in the fossil record. It's pretty much a crapshoot as to how things are going to fossilize. But we can see these events where all the different types of life suddenly cease. And we've seen graphs. We've seen either five or some people count previous extinction of events. And each of these events carries with it a signature or several signatures in the rocks. So things that can cause extinctions include climate change. Include volcanism and volcanoes, spew carbon dioxide and sulfur things into the atmosphere. Combinations of events can lead to weakness in the biodiversity which may be tipped into a mass extinction by some precipitating event too. A couple of examples of these types of events. Things that we can be careful of, things that might have been seen in the past. There's, for example, a hypothesis about hydrogen sulfide being emitted from the oceans, H2S. May not smell like rotten eggs and in small doses it's merely unpleasant. You guys are very sensitive to this chemical. It smells terrible. But it doesn't take much of it, doesn't take many parts per million of it for it to quickly build up into toxic levels. If we have anoxic ocean floors perhaps because of global climate changes that changed the way in which ocean currents run then there's a risk of H2S, another hypothesis, is the melting of clathrates. Clathrate is a term of like one compound crystallizing with another and the one I'm thinking of is methane clathrate. It's basically methane hydrate. So methane and water under high pressure form a solid. And it's thought that there's all sorts of this solid on the margins of the continents where it's cold enough and high pressure enough. Almost like a snow line on a mountain in reverse. The deeper you go the more of this stuff would be. For oceans warm up that stuff destabilizes and pumps methane into the atmosphere. There's a greenhouse gas and that accelerates the climate change. So moving forward we are going to leave traces in the fossil record. I believe we're already doing so. There's going to be a micro plastics layer in rocks and sediments around the world that will define at least our advent on the stage much like the iridium traces at the KT boundary define or point to an asteroid impact 66 million years ago. This layer is going to also probably show things like unusual isotope abundances. We can expect different isotope levels than we would expect from a baseline simply because we've had clear accidents and we've had above ground atomic testing. So going into the future there are all sorts of weaknesses in the biosphere that we need to be careful of. We need to have an environment that supports agriculture. Fertilizers are necessary for to feed everybody on the planet. The nitrogen infertilizer is primarily coming from the Haber-Bosch process and basically you have to take nitrogen and hydrogen which is made from hydrocarbons giving you CO2 and you have to pressurize them over iron powder at like 500 degrees Celsius. Again heated up with fossil fuels. This is a way of turning fossil fuels into ammonia which is used as fertilizers to feed people. Not really sustainable thing. Especially when you consider there's other elements in fertilizers we have to be careful of. Phosphate comes from rocks it's mined and when we look at how many more phosphate bearing like rich deposits there are that's going to put an upper limit on the type of agriculture but maybe it's a couple of hundred years more or less. So essentially I didn't want to give a huge presentation but I did want to give confidence in how we know what we know about the geologic record and these extinction events and emphasize that the extinction event we're going through we are not immune to it from our activities. And with that I'll pass it back on to Mike. Thanks Mike. I appreciate that perspective. I do kind of want to take this opportunity even though we're a little bit low on time. I do want to kind of expand on this notion of the network collapse. I think what I'd like I linked to an article up there just to kind of it's a little bit of a contrarian view I suppose but I think it is worth talking about. Let me see if I can find the section here. So this is a guy Doug Irwin who I don't really know who he is but apparently he is a member of the Geological Society of America I guess he's a Smithsonian paleontologist so in this Atlantic article he has a couple of he has some interesting thoughts if we're really in a mass extinction then go get a case of scotch people who claim we're in the sixth math extinction don't understand enough about mass extinctions to a certain extent they're claiming it as a way of frightening people. He says it's a network collapse problem just like power grids network dynamics research has been getting ton of money from DARPA. They're all physicists studying about it. The secret to power grids is that nobody knows how they work and it's the same problem in ecosystems. Irwin's other point that the magnitude of the big five mass extinctions and there's past dwarfs humanity's destruction thus far as he talks about passenger pigeons and how there were enough of them to blacken the sky at one time but now they're all gone and he questions but would there be any fossil record of them? This massive population might not leave any fossil record and he says when mass extinctions hit they don't just take out the big charismatic mega fauna like elephants or niche ecosystems like cloud forests they take out hardy and ubiquitous organisms as well like clams and plants and insects. This is incredibly hard to do but once you go over the edge and flip into a mass extinction mode nothing is safe mass extinctions kill almost everything on the planet. So that's a pretty compelling statement and again sort of begs the question about sort of where are we in this process? The idea he mentions insects specifically and the idea that insects populations are declining is alarming because insects I think would be a significant trip hammer into a mass extinction network collapse. Right so I mean I think the point is you know we should still be acting whether or not we consider this to be a current mass extinction or not and I mean because you're defining things geologically and humans don't live on geologic time it becomes very difficult to compare those things really to each other but I think there's at least some benefit to having that discussion hopefully in order to help enact action and changes in policy and in the way that we handle conservation there is some value to considering this as a large extinction event that is largely human driven. Yeah and I think you know one thing that makes this current six mass extinction different is that humans are alive to observe it. You know in the past you know this was the you know the life was just a victim of the circumstances leading to extinction but now humans exist and we are seeing it happen and we're documenting it and maybe that is maybe that's a new wrinkle in this phenomenon where you know whereas perhaps in the past maybe it would have been too late the network would already be collapsing and there's nothing we could do there's nothing that could stop it but now humans exist and maybe there is an opportunity to intervene there you know in other words the the we can we can change the algorithm of the network collapse and there still may be time to do that. So if no one has any other I guess concluding remarks or thoughts do we have any comments in our nearby chat here? Let's see let me scroll up a little bit here see what people are talking about. So I'll just say like I don't think we're at the point where we can't do anything I certainly think there's lots of efforts that we can and should be doing so I think in that sense you know we're not at a point where everything's going to just collapse and we might as well just drink ourselves to death so I think there's opportunities there to to really make impactful changes and even if we can't fully stem the tide of change we can at least kind of lessen the blow a little and I think that's definitely worth our time and energy. Yeah Alex I also just saw your comment in nearby chat that there is a fossil record of passenger pigeons. So that's it yeah so that's very interesting okay so okay well I think that's pretty good I think that's a pretty good stopping point I think there's some looking through the comments here and I think what you all have been saying I have come down to that also I did want to put in that contrarian view I just feel like it wouldn't be fair to exclude it from this discussion but it does seem to me that evidence suggests that it is certainly worth making whatever efforts we can to you know to save what we can and so with that I so hopefully on that optimistic note why don't we go ahead and and bring today's discussion to a close I want to thank my panelists for all their work preparing their slide presentations and gathering their thoughts for this topic and also thanks to all the students here attending today and we'll look forward to another one next month.