The History Of Earth's Five Mass Extinction Events [4K] | The Next Great Extinction Event | Spark

[Music] there's a way to make an entrance my destiny it was now a conspiracy of witches download veli today [Music] so [Music] [Music] [Music] extinct the very word is chilling it means that a species no longer survives in this world already there have been five great extinction events in the history of our planet what if the next species to be obliterated were us we pay scant regard to the planet-sized mechanism churning below our feet and over our heads we are after all the apex species of planet earth we flourish we consume and we drive the natural world to oblivion only when a dramatic event strikes earthquake eruption tsunami are we reminded of nature's awesome force sometimes for reasons we shall explore earth and the species on it come to blows are we next to be knocked out history teaches us only what to expect we have at least those five catastrophic planetary events to learn from if we are to avoid a human calamity [Music] the earth has suffered five great mass extinction events and this has been since the last half a billion years these have been dubbed the the great five or the big five the first recognized one is the end or vision x mass extinction which brought to an abrupt whole sort of a big diversification event where lots of new groups evolved it's not known whether there were really any plants at all on land before that and it's now thought that the main reason this happened was a massive ice age very brief probably less than a million years in length for comparison our current ice age that we're in has lasted for at least two and a half possibly five million years so this was very brief and very sharp so sea levels fell very quickly lots of environments were lost and then it ended abruptly again sea levels rose again so it caused more disruption certainly after that we've got evidence hard evidence of pollen from the land and even some insects and things showing that life had moved out onto the land during the late autovision and into the solarium but after that soon after that they actually started to evolve into large trees during the devonian like saline and into the devonian and so there are what we see today known as lycopods are club mosses little moss like things that live near water still um and today they're quite small but they were able to grow into these large trees the first large trees and first forests and these forests actually altered we have evidence they altered the carbon cycle because these large trees were able to grow across the empty landscapes they their roots dug down into the soils and they and they caused extreme erosion and so soils were actually then washed away into the oceans and this changed the whole carbon cycle the next one was the late devonian mass extinction um in that case it appears that lots of the ocean just suffocated basically there were things going on that caused the ocean to lose a lot of its oxygen possibly newly evolved land plants caused a lot more erosion by digging in their roots and causing nutrients to run off causing algal blooms which sucked oxygen out as they decayed and it a lot of evidence does point towards the change these significant changes on the land and to the carbon cycle as um being one of the primary drivers of the mass extinction and so the ocean floors became sort of dead zones and and there were several pulses it wasn't just one individual event so this spread out over millions of years quite different to the previous one as i mentioned it's hard for people to really imagine this but there are more types of animals in the past than there are today so even during right before um like before the dinosaurs at this point in time we're talking about the permian right before the biggest extinction event ever the permian triassic mass extinction there were huge diversities of different types of animals and really complex so-called ecological tearing as well arguably as complex as today and people don't realize that there are just so many more different types of animals and with each subsequent extinction we keep losing body plans so as today we if we're on the verge of another great extinction we can actually show in the past that this has happened where we lose all these body plans and there are some organisms which are really rare today and they're on the brink of extinction and we can actually see we're going to lose major body plans again unless they're conserved but we can actually look and learn a lot from the fossil record to show what actually can happen after a mass extinction and how the world changes or can change [Music] the largest mass extinction event ever to occur almost entirely wiped life from earth the greatest extinction event to ever strike the earth occurred about 252 million years ago this is called the great dying but it's at the permian transit mass extinction boundary so at this point in time as far as we know from all of the the fossil studies that have been done in terms of all the geological sections around the planet on land and in the sea we know that that the extinction magnitude was on scale that we just really can't imagine that about 95 of all life on the planet becoming extinct it was the only mass extinction that affected insects as far as we know the other ones seem to not affect insects as much and it um it's thought to probably be caused by a whole combination of uh of events that caused this perfect storm of bad environments so you had things like a major greenhouse event spike a place warmed by up to 10 degrees very quickly probably possibly multiple times there's even the thought that a new type of bacterium evolved that was able to decompose carbon on the sea floor and turn it into methane which is a powerful greenhouse gas so this affected the carbon dioxide in the atmosphere and there's also a lot of acids and toxins released into the atmosphere so this would have really affected the life on the land and particularly the plants themselves so these huge forests were actually wiped out at this time and probably a lot of hydrogen sulfide came out of the oceans because they were stagnating and hydrogen sulfide is quite a toxic gas um and it caused a lot of things to maybe die out from that um and that took a long time to recover from it was sort of a what's known as a coal gap meaning there were no forests for about five years five million years um and a coral gap which means that there were no reefs um in the in the oceans for a long time um and the uh the oxygen levels in the atmosphere plummeted from something close to about 30 in the atmosphere um compared to today's 21 um possibly dropping down to 10 so that's like being on mount everest basically at sea floor in terms of the oxygen density as for the big dying that's that's more complicated because there's such a bad environment for such a long time that was caused by this these various factors and we can see in the fossil record that there's um the climate seem to just fluctuate wildly for a good five million years after the mass extinction so species that survived that initial dying still had to weather all these big changes that came afterwards and it seems like a lot of the ones that survived were generalists so we say today oh if there's another catastrophe it'll be the rats and the seagulls and the cockroaches that will survive and they're they are quite good generalists they can survive on just about anything um they're not specialized to any particular food or and they have rapid breeding cycles as well which helps so things like say an elephant that has a long breeding cycle they might not survive so well and only few offspring and that seems to be the pattern back then as well but there are other groups that seem to have weathered previous environmental changes that were knocked out some organisms such as the seafloor scavenging trilobites survived numerous extinction events one of the most successful organisms in the sea uh were the trilobites which were a type of arthropod they were successful for several hundred million years they evolved in the latest pre-cambrian as far as we know so we're talking about 550 or so a million years ago but they were extremely successful in the sea for various reasons um they also replaced several organisms that were really uh diverse such as the so-called cup animals or archaeocents okay which disturb their habitats and basically there was an arms race at this time so probably trilobites are in the top three groups that people know about when that when you talk about extinct things just after the dinosaurs and the ammonites they certainly were one of the very first groups that were quite dominant in the oceans thousands of species right early on some of the very best eyesight with the compound eyes and a lens made out of a crystal of calcite quite amazing the only animal to ever do that but they they had weathered many different events including i assume various different apex predators coming in from initially large nautaloids and then to the sea scorpions and then the armor-plated fish and they seem to weather all of those with all these defenses very spiny but at the end devonian extinction events they were heavily impacted and almost none of them made it through except for one small group that sort of still struggled on until finally getting wiped out in the permian so they were almost all um bottom dwelling on the ocean floor um really reliant on on seafloor so you have the legs you can sometimes see their tracks where they shuffled up the sediment and they they ate the uh the animals and and other creatures that lived in the sediment so if the seafloors were really starting to die and nothing sort of lived there their whole food chain collapsed so that i'm assuming is is a major reason why they just couldn't quite make it through they were heavily reliant on the on the sea floor as being full of oxygen and full of life it's quite sad because they're very cool animals i mean such a diversity and beautiful shapes one adaptable organism survived the great dying lystrosaurus went on to become the ancestor of dinosaurs and mammals alike including humans so during the permian in pangea we know from the fossil record that there are high diversities of tetrapods so four-legged organisms like this guy here which is called lysosaurus for some reason it had attributes that enabled it to cross this boundary relatively unscathed so we know by looking at the skeleton it probably did scavenge it had a barrel chest in terms of air capacity as well we know that the air was probably fairly thin it was basically life under a green sky very different from today because of the hydrogen sulfide gas very few other organisms persisted across this boundary and of course these were very important tetrapods because they evolved eventually into mammals okay including us in terms of recovery we estimate that it took about 100 million years for the ecosystems to recover after that mass extinction and then not too long after i guess a few tens of millions of years later the end triassic extinction occurred it's possibly one of the most mysterious ones because i think there's fewer causes that have been identified for it but it might again be uh big volcanic eruptions that caused big climate changes to occur massively volcanism can have amazing impacts on climate and the environment in several different ways so first of all if you have a big volcanic eruption there's lots of dirt and dust and chemicals that get added to the atmosphere and one part of those are sulfide oxides or maybe even hydrogen sulfides and these can first of all form sulfate aerosols these are really tiny particles that actually get into the really high atmosphere and they can stay there for a long time and by doing so they will shield the atmosphere it's like a blanket so incoming solar radiation actually doesn't get quite through when it becomes cold for a few days month maybe even years if it's a big eruption and it becomes darker if it's a really big eruption it might even become so dark that photosynthesis becomes a problem well um a lot of people think that the triassic was pretty much a stressed environment throughout largely due to the oxygen levels in the atmosphere remaining really low so um the oxygen levels in the carboniferous to permian um it's the big ice age there had gone up to 30 32 which is massive like compared to 21 today and largely due to the big growth in terrestrial forests that had evolved and it allowed all sorts of things to evolve giant insects towards the late permian even before the mass extinction oxygen levels really started dropping and indications are that in the early triassic oxygen levels stayed close to 10 or 12 which is half of what we have today it's really quite extremely low and it seems that they didn't really get up to closer to modern levels again until into the jurassic after the mass extinction um at the end of the triassic but the interesting thing about it is that it probably encouraged some groups to evolve really efficient breathing so if you think about the birds today they have circular breathing they don't really have to breathe in and out as much as they just have a they have lots of air pockets to really get the oxygen out and that might be a legacy of the early dinosaur ancestors evolving in the triassic to deal with these low oxygen levels so that stressed environment had some unintended consequences later which is why we see such success in the birds today able to fly which is high oxygen demand after that we have the big golden age of the dinosaurs that lasted for a long time until it was brought to the end by the most famous uh popularly famous extinction the dinosaur extinction at the end of the cretaceous in fact we now can date it to about 66.03 million years ago famously there was a big asteroid impact probably the biggest asteroid impact in the last half a billion years so we're talking upwards of maybe even a trillion tons of rock just hurling through space heading towards our earth and when it did actually reach our earth okay it would have gone through the atmosphere within a fraction of a second and it hit the earth created a hole that was probably about 30 kilometers deep and we know about 180 to 200 kilometers wide so that alone is pretty bad but there was also indication that there was a lot of greenhouse gases being emitted by these big volcanic eruptions continent-wise eruptions in india that cause greenhouse spikes and we can see that in animal populations that were pretty stressed already before the asteroid hit any organism even close to it would have been basically incinerated from the fireball okay so this again had this effect where it affected the base of the food chain because there was a dust cloud that enveloped the earth so it affected plants at the base of the food chain and again we had this propagating effect all the way up through to the apex predators so the asteroid might have just been the last um bad news for uh for all of life and um it uh yeah it caused the non-avian dinosaurs to die out but many other groups went as well at the same time so in our extinction story it's really important to differentiate between background extinction and mass extinction so when we actually look at background extinction rates we can compare the modern to the fossil record so we can actually delve into the geologic past by looking at organisms and what we see which is really important is that for example if we look at mammal fossils probably one mammal species per thousand years became extinct so that's background extinction if you look at the present day we estimate that in relative to background extinction rates the extinction rate today is something on the order of about a thousand times okay what it is if we look at the fossil record [Music] coming from a background of geology and looking into deep time we've it's been quite well established that there is a clear solid link between carbon levels especially carbon dioxide levels in the atmosphere and climate now it's not always the carbon dioxide that causes the climate change to start with but it's either the first thing that the change in carbon dioxide up or down is very closely associated with massive climate change so sometimes the carbon dioxide changes ahead of time so things like massive volcanism can cause warming in some cases like the ordovician extinction big mountain building that weathering actually draws carbon dioxide out of the atmosphere and that causes the carbon dioxide to plunge which is what probably happened there causing an ice age at other times it can be other causes like uh the earth's orbit can change its shape it regularly does that in a predictable way um and then those changes in the from the sun's radiation um causes a start in shift towards warmer or colder but then that initiates sort of a feedback with the carbon dioxide so the warmer it gets often the carbon dioxide goes along it starts going up as well which causes more warming which causes more carbon dioxide so carbon dioxide either um initiates the the warming or cooling or it exacerbates the the change and the quicker it changes the more rapidly the climate changes and rapid climate change often leads to species not being able to adapt quick enough and if the environments shift too fast for specialized species they die out and and if that goes above the what we call background extinction rates we start seeing um sort of the clear markers of mass extinctions and there is the thought that at the moment the change is exceeding the rate at which species can sort of adapt um and it's not like with all the other mass extinctions it's probably more a perfect storm of conditions um not just one like climate change or an asteroid but a host of things that we have not just climate change induced by humans at the moment but we have deforestation or urban sprawls or habitat fragmentation things like that that are stopping species from adapting at a fast enough rate so it's worrying to see where we're heading knowing what's happened in the past it's really important that we actually understand these species and the effect that we're having with all this deforestation and other things that are happening around the planet which is also affecting climate because another factor which affects species as well is in fact some groups of organisms are very controlled by temperature and even the slightest increase in temperature can affect their distribution and actually make their populations dwindle through time so there are various important factors and these factors that control uh species through time relate to ecosystem energy supply they relate to climatic events as well so various aspects of climate which are quite diverse when we talk about them it could actually mean about where they live they live on the sea floor in terms of bathymetry their depth constraints as well with sea level rise and fall that really affects them as well so there's a huge number of parameters that affect a species through time and space which are important to consider and with so many species becoming extinct we know that there's a massive problem in the environment yeah the ecosystems particularly the rainforests in south america and the amazon or across indonesia have been severely affected not just by the changes in carbon dioxide but initially by clearing and we also have our own very special rainforests that are extremely diverse up in the north of queensland and also an extremely diverse flora called the fin boss in both africa and south west and western australia so these are extremely diverse biomes and they're already showing significant extinctions um as a result of both clearing and changes in the carbon dioxide levels that we've seen which have been significantly greater in the last 50 years [Music] one of the groups that always gets raised is how did they survive but the others didn't is things like crocodiles and alligators they've been around for longer than the dinosaurs and they're still around and the recent massive freeze in florida was an interesting brought up some interesting images of crocodiles or alligators they're basically poking their snouts through the ice and getting frozen in and going into a hibernation state and so if you think about the in this case the mass extinction at the end of the dinosaur age the cretaceous where there was probably almost a nuclear winter from the impact um that was probably a perfect way for them to survive that where there was no food around for many years um so so they they had some ability to to just weather it whereas maybe some more active species like the sort of warm blooded um early birds um a lot of the dinosaurs that needed a lot of food the big ones they just couldn't weather it out for all those years [Music] if we pay attention to it one other event provides a lesson in carbon dioxide absorption in the oceans the paleocene eocene thermal maximum the paleocene using thermal maximum which is a mouthful we usually call it petm and was a very abrupt short warming event that happened about 55 million years ago atmospheric temperatures rose by five to eight degrees and what's interesting is that it's actually one of the biggest mass extinctions in the deep ocean and that's unusual because usually living conditions in the deep ocean are quite constant and we much more rarely see big mass extinctions there so what we know is that this event was caused by a massive release of carbon into the atmosphere still some controversy about where this cabin came from it might have been enhanced volcanism it might have been methane hydrates but certainly this release happened fast on a geological time scale and we now pretty much think that this release happened at a much slower rate than what we see today about at least 10 times if not 100 times slower and that has interesting implications because if you add co2 into the atmosphere the co2 will be absorbed by the oceans and when the ocean absorbs this carbon dioxide actually carbonate ions get depleted in the ocean and that's bad news for any organism that lives in the ocean that builds shells out of calcite or argonite because they need these carbonate ions to actually build their shells calcification rates the way that the animals build up their shells with calcium carbonate has dropped there are things that are becoming thinner in their shells which which makes them more susceptible to other stresses and and that's just an additional problem for them so climate change by itself isn't the whole story the acidification is a big issue and it has been in past extinctions as well you can see the effect of the ocean acidification in those mass extinctions in the past where shells get more um less stable and things like that and and the expansion of ocean dead zones is a big story at the moment as well where they've uh increased four-fold from what we knew maybe 50 years ago so so those dead zones as i've said from other extinction events are a big part of the stresses in these mass extinction events and they're undoubtedly occurring [Music] so the paleocene eocene thermal maximum was this unbelievable period in earth history when the earth really warmed up around the whole globe at temperatures that we haven't seen for a very long time so there were crocodiles living in the arctic there were forests and they're still preserved you can burn the wood from those forests from 80 degrees north latitude like the whole planet was a different place and it shows us that climate change is part of earth history it's a natural part of earth history the difference though is that even that enormous temperature change that whole change in the earth climate system occurred naturally over a relatively long period of time millions of years the difference with today is that that change is on the order of tens of years it's happening so fast that the natural systems are out of balance and that's a real challenge not just for us but actually for most living things on the planet [Music] i think it's uncontroversial that human activity of one form or another even without the climate change is causing things to go extinct and that's been documented for many things over the last couple of hundred years big mammal groups that used to be massively abundant are gone so um how much is really going extinct is very hard to tell because it would take half the population of the world to do sort of ecological surveys almost every year just to keep an eye on how things are doing there's obviously not those resources so as a paleontologist it's easier because it's all the experiments been done you can look at the fossil record as imperfect as it is things that are happening right now are hard to really definitively say but i would say that in the oceans especially things things like ocean acidification where the raising of the carbon dioxide levels in the ocean waters where most of the carbon dioxide is going at the moment um that little bit of acidification which is not that little it's gone by two decimal points which is about a rise of um well over 30 in acidity really because it's a logarithmic scale i think the fossil record tells us about events that have occurred in the past where carbon dioxide has run away in terms of quantity in the atmosphere we've also seen often coinciding with that those toxic gases and release of methane and all of these events have had dire consequences for ecosystems on the land and also in the ocean in terms of civil level rise all of the ice volume okay a lot of ice is being melted currently with the glaciers and in the north and also in the southern hemispheres so big changes are happening in the environment but they're happening very quickly and that's one of the big issues that humans are facing today well if left unchecked we know for sure that temperatures will continue to rise co2 will continue to rise acidification will continue and become much more severe um i think we already see the impacts right now lots of ecosystems really struggle to keep up with these changes and when temperatures change then animals of plants might be able to migrate to higher latitudes but maybe not fast enough maybe there will be whole new ecosystem structures that will need to be established ocean acidification is if oceans become too acidic to sustain certain life other winners other disaster attacks as we call them will certainly survive but it will be a very different world so sea level rise is due to two different physical mechanisms and one is of course melting ice caps and we see this happening right now greenland is melting antarctica is starting to melt more than we actually initially thought so there's certainly some tipping points there because once an ice sheet starts to melt it will continue to melt due to other feedback set so when an ice kit starts to melt it becomes less high the lower it gets the warmer it gets you know when you go up the mountain the higher you get the cold it gets so just due to this change in height it will it will start to melt faster also it will the surface will become maybe a little bit darker because there's not much more snow accumulation there will be more dust and other things that actually go on the surface and especially regions where it starts to melt completely what was white before will be replaced by rock or by whatever is underneath these colors are much darker they will absorb more incoming solar radiation and will become warmer so there's several positive feedbacks that kick in once an ice sheet starts to melt if we start to warm up our oceans the water in the ocean will expand and due to this expansion we will experience sea level rise oh listen people have been doing models for the last 20 years on you know changes to the environment that are undergoing at the moment and every time they produce a model they have to revise it because the natural system is going faster than they modeled so the arctic ice for example that's down to about a third of its size that was only 20 years ago and so these systems are changing incredibly quickly the danger is that we have this enormous system called the ocean that absorbs a huge amount of energy because it's so big but once that reaches that tipping point and we start melting the ice and temperatures start to rise faster than they are now which we know will happen all the models show that then we're in uncharted territory and those changes are very hard to adapt to for humans um i i think we are very vulnerable right now there's lots of humans on this earth and we all depend on a few several belts a few regions that produce most of our food we depend on water with changing climate precipitation patterns will change temperature will of course change will these structures we have been putting into place over the last 20 years will they still work will they be able to actually support all of us i think that's highly questionable on top of that of course we will see sea level rise all these things will also happen if we stop emitting right now but um it will be maybe easier to deal with the consequences the sooner we stop it might just be too late at some point at some point very soon i think as humans we've been able to [Music] do some amazing things with our own needs like the crops we've been able to genetically modify to try to increase the amount of food resources that we have to try to provide for these you know huge increases in population in humans but i think um the question is can we keep pace with um the increases in carbon dioxide in the atmosphere and the changes to our climate so we're seeing much greater extremes of climate and much greater extremes of very hot dry events particularly here in australia so it's a question of whether we're able to keep pace with those changes even with such technologies as genetic modification so that the anthropocene is now a word that's very widely used uh it's still not formally defined there are people who are working on that in fact there are people here in our building in our school who are working on that they've just had a paper about uh uh an actual marker for the start of a new geological era the the first sort of nuclear bomb spike that is recorded in tree rings for example but yes i think there are many arguments that suggests we are entering a new geological era so there's two things to think about here one is are we entering a new climate state and i think most people would agree definitely yes but in terms of geology they have to think about what's preserved in the rock record the geological record and absolutely there too we are into new there is actually a new rock forming now that's made up of solidified plastic and that will not break down over time but that is a new rock type that's been found offshore of hawaii and various other places and there are new chemical elements because of these nuclear explosions preserved in the sedimentary record of the sea so geologically yes and because of the increase in the amount of rainfall the amount of temperature the rate of erosion is faster than we've had before so there are thicker sequences of sediments in the deep sea that are accreting so that is a recognizable change that we could see in the geological record so aside from the pedantic niceties of saying geology there are physical changes recorded by earth in this sort of rock record that are suggesting we're into a whole new period changes in our oceans such as releasing toxins and plastics can also have dire consequences for the diversity that we see in the ecosystems today again i'm not a biologist but in my opinion yes i think we're in a period of mass extinctions um it's not the normal background extinction rate the fact that every one of us has seen many species going extinct during our lifetimes that really shouldn't be the case so yes i would say so so are we entering the sixth great extinction event many would say we're already in it we haven't entered we are not entering we are in if you look at the amount of species that have become extinct since really the the dodo and the passenger pigeon in the states from the late 1800s since then the rate of extinction of species is also one of these exponential curves i think that the evidence points to a sixth mass extinction if we were able to time travel into the future and look back at the fossil evidence from today we would see um the last 10 000 years in a very um short space of time so we would see that the mega fauna that were like the sabertooth tigers and the giant bison across america or in australia we would see that megafauna like our marsupial lions and giant kangaroos and giant wombats would all become extinct in a very short space of time as well as the increase that we see in extinction of species today so i think that we have already entered this sixth mass extinction in the anthropocene and you know the danger is that there are so many species that are uniquely primed for very specific purposes when that purpose changes say the size of a flower the growth up a horizon of a mountain chain where they live you know there are birds that only live within 400 feet of a particular mountain they're being forced up the mountain and eventually they're just going to have to go into the sky their habitats are disappearing as we speak because they're so fine-tuned for life so as the habitats change whether for good or bad you know climate change brings more growth in some areas less growth more dry in others but that change means that species will go extinct a major issue that we as humans face today is species loss and this is occurring through deforestation buildings this is happening all around the planet and what's happening is a species ranges are becoming contracted dissected and they cannot move between one place to another so this will affect the gene pool as well and genetic diversity because there's really a minimum number of a population in a population to sustain that species through time and also in space now under natural geological earth processes nature would adapt and new species would arise to fill those gaps but because the change is so fast now nature cannot adapt at that speed and that's the danger we're left with a very few successful species that can adapt to change and we're one of them we can adapt we live everywhere on the planet so for us it's all fine it's not fine but we can adapt to that change but there's so many species that can't and they are disappearing now but my personal concern is really the change above all is a change in chemistry in the ocean and also the change in water availability and what is going to happen to our ecosystems because our ecosystems are already under stress due to climate change but on top of that we add stress to to overfishing over hunting habited fragmentation habited loss i think there's only that much that these ecosystems can take and in a way we are part of an ecosystem we need an ecosystem to live ourselves we need to eat we need to drink one of the things about geology is about rocks about processes that you know are preserved in rock record is that they compress time so you know where the dinosaurs went extinct that was probably over a million years but we can see that as a layer about that thick so if you think about all the change that's happening now all the plastic and pollution that's going into the environment as that goes into the deep sea and gets buried and buried and worried it gets compressed from these very thin layers so that will have this enormous geochemical spike of all these manufactured components that will be preserved under a very thin horizon so millions of years from now if i was able to travel forward into the future and then come back and look and say what has gone on here because it's so compressed so much change is going on at that one specific interval this is a massive catastrophe that would be recorded all around the globe so you get these runaway effects and so runaway effects and we're already seeing it right so more than half or even three quarters of the world's population live in low-lying areas at fertile river deltas at the coast of the oceans all the big cities in the world are where there's a nice view over the ocean right so now if the ocean rises 120 meters omg the deltas the fertile deltas where all the rice is grown where all the grain all these things are grown they disappear and so as those oceans flood and some people have suggested this can happen on the order of 100 years more than half of our food source is gone fishery stocks are being depleted around the world and those are primary food stocks primary food is the key if we don't have the primary food stocks and fresh water the basics of life it's not about whether you've got a mobile phone or a computer it's about whether you've got food and water and so if we don't have food and water our population will totally crash [Music] but less human pressure allows nature to expand there's a lovely example in chernobyl where the nuclear disaster happened in russia the forests the whole city was abandoned and forests have come back wolves have come back for the first time in generations there's a viable population with moose there's a whole ecosystem and a chain that is set up so we know that nature can come back it's allowing it the space and the time to be itself i think that the world we know today won't necessarily exist for too much longer if we keep increasing our carbon dioxide but i think it's more the humans that we need to worry about we're the ones who evolved in these much cooler times much lower carbon dioxide in the atmosphere times and it's whether we can help the species that we require and out keep our diversity on earth into the future and make our own species survive so yeah we've got carbon dioxide rising we're changing we have to mitigate how we build where we build we're planning about the future building back on higher ground you know transporting water using wave energy all these kind of ideas about adapting to the new if you then throw something on top of that adaptation for many including our species that could be too much yellowstone going off would be a cataclysmic disaster yellowstone is known to have covered a third of the u.s in death causing ash and gases not to mention all the cloud effects and global changes in temperature cut emissions now as fast as possible i think climate change is actually the biggest threat humanity has ever faced and it's an interesting threat because it's something we have to do something all together in terms of pollution for example if you have bad pollution in one country then one country can decide that's not good for us and they change their policies and then it will be fixed in this case a whole human species says actually to cut emissions the faster the better

Channel: Spark

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Id: -Jsj7K6E0Fg

Length: 47min 55sec (2875 seconds)

Published: Wed Apr 13 2022