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Good evening. I am Stewart Brand from the Long Now Foundation and doing a serious long now tonight. Here we have a mathematical physicist who is doing something that is really at the core of what the Long Now Foundation has been trying to get out and I think I first saw a version of it back when I was a skydiver in the 1960s. The thing about sky diving is when you are in the plane somebody jumps out there right there in the wind and they get real small. Now when it's you jumping out you are out there in the wind and you push the plane away and it gets real small and that's pretty much how we live in time but one time there was this two planes, two stacks of jumpers and I was in one plane watching the guys jump out of the other plane. Guy gets out in the strut, let's go, you have to pull on this. I have never seen sky diving from the side before, it was horrifying. Shortly after that I had a malfunction which tried to kill me and failed but that - the combination of those two events made me stop sky diving and I am here today. I learnt, we seldom do that with time, in a sense what John Baez is here to do tonight is look at time not from within and where we are telescoping on one direction and telescoping on the other direction but looking at it from the side and seeing what kind of patterns emerge there and how you can get a handle on things from that perspective where you might do something about them if you don't happen to like them. Please welcome John Baez. Thanks very much it's great to be here. Stewart Brand and Kevin Kelly have been heroes of mine and so it's nice to be able to talk to them even if I am standing up here and the rest of you of course. So I am a mathematical physicist, so I usually think about things that are either bigger than that or smaller than you can see, but I thought I would do something a little bit more human in scale and talk about history and the weather and so right now we are in a very strange moment in history. Things are changing mighty fast these days as you, I am sure have heard there this thing called Moore's Law (ph), talking about how computers are working ever faster but really that's just a tiny bit of a much bigger story which you can see maybe pretty well on this graph here. A lot has been happening in the last couple of hundred years and it blinds us to the overall scope of time. So this is a graph of population starting from approximately around the end of the last Ice Age till now and you will see that it ramped up in retrospect fairly slowly until the second agriculture revolution when modern machines started getting used for agriculture. And then it, shot up and so if you were to naively extrapolate a trend from this curve you would conclude that in about 30 years from now the population of the world would become infinite and that's the singularity when the earth collapses in to a black hole under the weight of all the people. Well we can tell that that's probably not really going to happen. It would be against the laws of physics. So it shows you have to be a little careful when you are extrapolating curves and luckily if you were able to zoom in on the top of this curve a lot more finely then we have accuracy here. You would see to your relief that it's beginning to slope down slightly, not slope down slope up less fast. So there is a little hope for us. But the problem I want to talk about is not what's going to be the most likely continuation of this curve. It just has to do with trying to understand time on a large scale. Trying to understand history when we are standing right here is a lot like trying to understand geography when you are hanging on to a cliff. You think of geography is vertical but most of it's not. But you just can't see it and you are scared stiff. So I want to zoom out a bit, and see what history is like on a slightly larger scale and of course, history is incredibly complicated. So I thought I would focus on something we all know something about namely the weather. So the weather is an hot topic these days because all this rapid expansion in human population and other things like technology goes along with burning stuff. We basically fuel our existence these days by burning carbon and just like the population curve shoots up all of a sudden in the last 2 centuries or so, same for the CO2 carbon dioxide emissions mainly from burning oil, coal and gas as you can see here. But you can see how remarkably it's shot up from what looks like nothing to quite a lot and of course, that has an effect on things that has an effect on the weather. It has an effect on the air first of all, so here is a graph over the last 40 years, I guess, of how much carbon dioxide there is in the air. The red curve is the real thing measured in Hawaii, the blue curve is sort of an averaged out version of that. And you can see it's been going up. Of course, you can make any graph look scary if you plot it correctly. So you should always be careful and look at the bottom of the graph here. So its not starting from zero, don't blame me for making this graph, I would like to start things at zero and make it look a little less scary but still it's pretty scary because it's gone from 300 parts per million to about 400 parts per million in the last 40 years. So that means there is about 30% increase in the amount of carbon dioxide in the air. Over the - just the last 40 years and as we will see 40 years is a pathetically small amount of time over the, if you measured in geological time scale, so for the earth's atmosphere to change so drastically in such a short time is really a unprecedented thing or almost unprecedented thing. So that's what I want to talk about. Of course, you have heard a lot about global warming but unfortunately usually what you hear about it only focuses on a tiny sliver of history which doesn't really give you enough of a view of it, to really see what it's - what it's impact or what its significance is. Just in case you are curious, the wiggly red curve there has to do with the fact that there is an annual cycle in how much carbon dioxide there is in the air. Most of the plants live in the northern hemisphere and so when its summer in the northern hemisphere they eat up carbon dioxide and the carbon dioxide goes down and then during the winter it goes back up and all this is very beautifully visible on that graph. But any way the increase in carbon dioxide goes along with increase in temperature because infrared radiation leaving the earth trying to get back out to space gets absorbed by carbon dioxide and so we have been seeing an increase in temperature ever since the industrial revolution, roughly 1860 here in this graph and you can see it's a very complicated wiggly curve, the blue curve is the real thing, the red curve is averaged out, so you get a more of a sense of it but you can see any way that it's temperature averaged over the whole world has gone up 8/10ths of a degree Centigrade or I guess, that's something like 1.5ÃƒÆ’Ã¢â‚¬Å¡Ãƒâ€šÃ‚Âº F over the last, I guess, roughly a 150 years and that's a big deal but it doesn't sound like a big deal when you first hear about it. If someone says well the temperature went up 1.5 degrees you say well that's not a big deal. But the reason why you can't tell, even whether it is a big deal or not is because we are looking on such a short time scale. So to see what's really going on, you have to zoom out to a larger time scale to see if this just some random wiggle that will go away or what. So let's zoom out a little bit here. So instead of just looking at the last 150 years lets look at the last 15000 years of so, and see what temperature has been doing. This is actually the temperature in Greenland. Temperature up in places like Greenland are much more variable than near the equator, so this shows some drastic variations. They would be less if you measured it near the equator but anyway, you can get the picture pretty clearly. This is all from digging a two mile deep ice core in the glaciers in Greenland that let it go back and see yearly variations in various things like the ice - the concentration in the ice and get a sense of the temperature over that time period and you will see the main thing here is that there had been an ice age till around 12000 years ago and then it warmed up and it spans surprisingly even in temperature ever since. So we have lived meaning, we, the we of recorded human history, we have lived in a sort of false sense of security in terms of thinking that the climate is more or less constant when in fact if you go back just a little bit further you see there are much more jagged variations in temperature. So that rise in temperature that I showed you on the last slide is just a tiny little thing right there. And so if you look at that, then you might say well gee, what are people worried about, about global warming, maybe we should be worried about the next ice age instead. And that's sort of true but we will see, there are different views you can take on this. I just want to talk about a couple of wiggles on this curve. So I will first of all talked about the tiny little wiggle called the little Ice Age which is a little dent right next to that bump there but because it's fairly recent it has its own name whereas most of these wiggles of course, don't have any name. And then I want to talk about a more interesting, well not more interesting but more substantial wiggle which is called the Younger Dryas episode. So right as the last Ice Age was ending for it was warming up, then the temperature plunged around 13000 years ago and that's an interesting story in itself. So lets just take a look at those and we got a sense of what kind of things the climate can do. So the little Ice Age was from around 1550 to 1850 and the temperatures in Europe dropped about 1ÃƒÆ’Ã¢â‚¬Å¡Ãƒâ€šÃ‚Âº C so its about 1.5ÃƒÆ’Ã¢â‚¬Å¡Ãƒâ€šÃ‚Âº F or so. Near the equator apparently it was a bigger deal. It was about a two degree change. But it was noticed by people at the time just due to the fact that winters were colder than they had been and people have done studies of paintings, the history of paintings and they find more of these kind of scenes during that stretch of time. There is a lot of controversy over how big a deal that that fluctuation was - that is how much it actually mattered. In particular it's an interesting question because it ended right when the industrial revolution started around 1850. So we may have ended the little Ice Age by pumping lots of carbon dioxide out into the air. So maybe it wouldn't have been so little if we hadn't done something about it, regardless of whether we wanted to, we did. So that's a little wiggle, it makes people be able to walk around on the ice in the winter in the Netherlands whereas now they can't. But a bigger wiggle was this younger Dryas episode which began about 12900 years ago. So that was a shocking event. In only 20 years the temperature in Europe dropped by 7ÃƒÆ’Ã¢â‚¬Å¡Ãƒâ€šÃ‚Âº C on average and that lasted for a thousand years and then suddenly in another 20 years it ended. So what 7ÃƒÆ’Ã¢â‚¬Å¡Ãƒâ€šÃ‚Âº mean? Well 7ÃƒÆ’Ã¢â‚¬Å¡Ãƒâ€šÃ‚Âº means that France and Germany became Tundra and Scotland had glaciers on it and you can see, if you can read these not too readable letters, that the climate was really drastically different in Europe than it is now. So our ancestors who were just beginning to practice agriculture at around that time had to put up with a thousand years of cold really, really cold weather and luckily I guess, it didn't kill us off, we just may do. And then all of a sudden in another 20 years it popped right back up to what we know now. So this is an interesting question. Why did that happen? No one really knows why it happened. There is a theory which is interesting which goes like this. So you have all heard that the reason why Europe is warmer than a comparable place up here in Canada is because the Gulf Stream carries heat from the southern latitudes up past the coast of Europe. In fact it's, I just heard recently that that's somewhat controversial among scientists these days. They have really been trying to understand exactly what's going on and it's not as clear as you might think. But according to this theory which I am telling you, which was a popular theory for a while, the key to understanding the Younger Dryas was this current flow which keeps Europe warm and an interesting thing happened which is that towards the end of the last Ice Age Canada was covered with glaciers and so the edge of those glaciers there was a lot of glacial run off, melted ice formed lakes and there was a huge lake called Lake Agassiz, which is that light blue thing there, which has by now shrunk down to smaller lakes like Lake Winnipeg. So in Manitoba there. But this Lake was huge and it was blocked from flowing to the sea by ice. It was blocked by lots of ice but it's known that several times it actually managed to erode its way through that ice and there were huge floods where the lake emptied out through the St. Laurent sea way and up in to the north, poured out into the North Atlantic. This is known through studies of sediment at the bottom of the North Atlantic. There are actually lots of periods when this lake would bust free and carry lots of rocks and it would be layers of sediment. But it's possible that the fresh water from that lake was enough to screw up the Gulf Stream and ironically the melting lead Europe to get a lot colder because the Gulf Stream was blocked. So in fact if I had given this talk about 6 months ago I would have just said this is the truth, this is how it works. But recently people have started doubting that for various reasons both because they don't think the Gulf Stream is quite so significant and also because they have done a lot of ice course in mountains in the tropics. There are some mountains like Mt. Kilimanjaro and other less famous ones that have ice even though they are in the tropics and they discovered that the Youngest Dryas episode was just as pronounced there and maybe even came before its appearance in Northern Europe which would mean that there was some other cause perhaps for why Europe got frozen. So that's just, I think, a mystery at this point. It's a pretty important mystery though because suppose it was fresh water pouring into the North Atlantic that made Europe get cold for a thousand years, well then we should be a little bit concerned because that's what's happening now. Right now Greenland and the Arctic are melting. So there is a picture of how Greenland has been melting over the last 10 years and down below is just a picture of the Arctic melting away from 1979 to 2005, these are pictures during the summer when the ice is at it's minimum and you will see that there is a significant amount of change there, in particular now there is something called the northwest passage You may have heard about if you heard about all the explorers were trying to find some sneaky quick route to get from Europe to the Western United States by sailing north of Russia or back when they were looking for the northwest patch which didn't exist because it was snow blocked or ice blocked at all times of the year, but now it does exist and now in fact oil companies are taking advantage of it to ship their oil during the summer months north of Russia. Of course, they helped create it. Maybe its just all part of an elaborate business plan, I don't know. But this is a significant amount of melting if you think about it, especially if you have to imagine yourself thinking on the scale of thousands of years the Ice Age ended 10000 years ago, now here we see in just 30 years the remaining bit of the polar icecap is shrunk significantly. So people have noticed that there is a lot more fresh water going into the Atlantic, the salinity is going down and some people are worried that it could trigger another Younger Dryas event but we don't really know. So we don't know if that's going to happen but to get a better perspective on this kind of thing we have to zoom out a lot further. Just looking at the last Ice Age really isn't nearly enough to tell what's going on. It's just like, you know, looking at the last night you say, oh yes, there is a period of night and ever since then it's been day. Well, that's sort of the attitude the people have. In fact they have this silly geological timing system. This is a great book, this book is not silly. It's called the Holocene. The Holocene is the name for geological period though which is the period after the last Ice Age and that sort of like having a name for the day and then before that there was night or something like that. It's just the it's the geological periods get shrunk in a silly way when it get near to the point when we show up on the scene. Anyway we have to zoom out to see what's going on. So 150 years ago, we have the Industrial Revolution and the start of this human caused warming. 1500 years ago well, there were widespread empires, 15,000 years ago, that's around the tail end of the last Ice Age as we have seen so that Younger Dryas kicked in around 13,000 years ago but you need to zoom out a few more powers of tens to really see what's going on. So you have to go 150,000 years ago to get to the tail end of the previous Ice Age. So Ice Ages have been going on for a while and they happen roughly in a very irregular way about every 100,000 years or so. So you really have to see a number of them before you can tell what's going on. The Ice Ages started, the serious Ice Ages started around 1000, sorry, 1.5 million years ago, so that means there has been about 10 Ice Ages since then. And but the Ice Ages didn't start all of a sudden. There was a period of cooling as we will see that that lasted quite a bit of longer than that. So if you got another power of 10 you get the 15 million years ago and the cooling of the earth's climate was well underway at that time, that's when apes just began to split off from other kinds of monkeys. And so we have to look at all of these time scales which we notice are significantly different powers of 10 here to see what's going with the climate. So let's zoom out a little bit and see what we see. So here is a bunch of graphs illustrating the climate at different time scales so that at the bottom here is the last 150 years. So this is measured in kilo annums or thousands of years. So that's a 150 years there and you can that's basically roughly since the Industrial Revolution and you can see it's been warming up with lots of wiggles and it's been warming up approximately a degree in that amount of time as I said. But, okay, that's way too small to to see anything interesting. So let's zoom out by one power sorry, no we are zooming out here by two powers of 10 and - jump up two powers of 10, so this is 16,000 years, so that's the end of the last Ice Age, here is the Younger Dryas and here is this nice wiggly, fairly constant weather we have been having ever since. And you can see it's warmed up for about five degrees since the end of the last Ice Age. But we have to zoom out further. So okay, let's zoom out to go back a 150,000 years ago, then you see that all this warming up its been going on is this little thing here and you see that in the last 150,000 years basically what happened is we had an Ice Age. It got very cold and then zoom, it warmed up. So the way this particular last Ice Age went was, it warmed up suddenly, cooled down and then warmed up suddenly. But that's just one of 10 Ice Ages, approximately 10 Ice Ages that's happened in the last million years. So, well, you can really count Ice Ages as you see here. Counting Ice Ages is counting the number of dents in this picture but we have to decide how big they have to be to count. It's just a very complicated thing. So there is the last Ice Age but you can see that there have been a bunch of them and so that's what's been going on. But that still a bit mysterious because it makes you wonder well how long is it been going on like that and what happened before that. So let's zoom out a bit more. We really have to zoom out quite a bit more to see what's really going on and so here I'm zooming out to 65 million years ago. So the stuff I showed you before was just this period called Rapid Glacial Cycle, just this little bit here was what I was showing you before. 65 million years ago is a good time to start because that's when the dinosaurs went extinct in a rather dramatic manner and so this has been sort of the era of mammals. And you can see some interesting stuff has been going on in the last 65 million years. So basically, in a nutshell, it warmed up for a while and then cooled down quite a lot. It warmed up till around 55 million years ago. Interestingly paleontologists talk about an optimum when it's as warm as possible. For some reason they like it to be warm. So so from their point of view you think oh, global warming, yeah. So but so the optimum so to speak or maximum I prefer to call it happened 55 million years ago. It cooled down and then whomp! It took a big dive around 35 million years ago that's when the Antarctic froze over. So for through most of the history of the earth there haven't been icecaps. Around this time there were crocodiles in Antarctica and palm trees and ferns. So the formation of the icecaps in the North and South Pole happened around then and so that's a big interesting puzzle, why did it happen? We are used to it but it's an unusual thing. It melted the Antarctic melted for a while and then it froze over again and its been getting colder ever since but even more interesting in a way than the fact is its getting colder is the temperature variations have been getting bigger. You know this the curve gets really jittery near the edge here. So were the time period it's quite a bit colder than most of the history of the earth and also much more erratic. These wiggles happening about every 100,000 years ago or so, every 100,000 years or so. So the Holocene is probably that little black vertical line right at the edge of the graph the so called present. The that's what they call it, the present the nice period of time. Eventually if humanity moves long ago they say well, back in the present you know, its going to be sort of embarrassing terminology - sort of like post modernism. So anyway, the period of these big Ice Ages is called the Pleistocene, that's a skinny little period there, then the Pliocene and the Miocene, the Oligocene, Eocene and Paleocene. I want to tell you all a little bit about the history of this stretch of time because its if you think about it on the grant scale of things its sort of the time period when the things were more or less like they are now in the sense that there are mammals or the birds being the dominant life forms where as before things were very different. So this time period started out with a bang quite literally. 65 million years ago, an asteroid that was 10 kilometers across or six miles across slammed into what's now the Yucatan Peninsula at an impact site Chicxulub which means "Tail of the Devil" and that as we'll see is what probably killed all the dinosaurs but there are some interesting other things to be seen in this map. You will notice that Antarctica was not by itself it was connected to Australia and a lot of other features of the earth are very different, in particular India had not yet slammed into Asia. And this probably has something to do with why the climate was so much warmer then although it really is somewhat mysterious. So what happened? This is a really beautiful. It feels like scene here that was painted by someone at NASA. This looks like one of these new age posters. But what it is - is one of the biggest disasters that's ever happened in the history of the earth. It's a nice picture though. So this enormous asteroid, 10 kilometers across slammed into the Caribbean, into the sea and millions of tons of rocks were thrown up into the atmosphere, lots of molten core shot around the whole world. People see little droplets of cores that have been melted all around the world. It set wildfires all around the world. You can - if you go to my website, you can refer, probably you can get to some links that show the spread of the wildfires that people, you know, theorize happened at that time because of these molten cores. And the - what that caused was a huge ball of smoke that wound up killing off the dinosaurs. Here is a picture of the actual impact. You can see it came in at a slant, they know the slant that it came in. It sent a huge tsunami 50 to a 100 meters tall shooting over Texas - unfortunately, way too early to do any good. Sorry for any Texans in the audience. I am not I'm not talking about all of you. And the other the big effect of it was that it made the earth get dark for about a year. Plants basically were unable to photosynthesize completely for about couple of months and so the dinosaurs died off. And that set the stage for us. Well, not quite us. So, although I say, things are more or less like we are familiar with, in the sense that birds and mammals were dominant. Birds had the upper hand for a while there. So, in fact it's true that the largest predators for several million years were these eight foot tall Diatrymas or terror cranes. Here you see one eating a horse, which makes it look really huge until you remember that horses were this tall at that time. So it's not it's not like Godzilla. It is just a pretty darn scary bird. But eventually somehow they died out, probably - partially due to the cooling that occurred and things became a bit more like the recognizable earth we know. So 50 million years ago, after 15 million years of warming up, what happened was that Antarctica separated out from Australia. And also shortly thereafter, not in this map, the India hit Asia forming the Himalayas and the huge Tibetan plateau. And these things are two of the prime suspects for why the earth got colder starting around then. For one, having Antarctica being separate from other land allows the ocean currents just to keep going around and around Antarctica, which means that it doesn't need to ever warm up. I mean, nothing is warming it up, where as when it was connected to other landmasses all the currents had to loop around and so warm water would be hitting Antarctica and people think that's why it was kept warm before, but not now. The Tibetan plateau also has a huge impact on the climate. So the more snow you have around, the colder it gets, because snow is white and it reflects light. That's the basic instability in the climate system. When it gets cold, it gets white and that makes it colder. When, conversely we are seeing now that the snow is melting, large portions of the North are warming up even faster, because dirt picks up a lot more heat than snow. And in fact that, if you think about that, it makes you wonder what in the world is keeping things in balance? It is just the opposite of a feedback mechanism that keeps things stable. It's a feedback mechanism that makes things get thrown off. I could talk about that but I guess I won't. But I will mention that there was a period before the Cambrian cold, the period of snowball earth, when they believed the whole earth was completely frozen over due to this kind of out of the whack feedback. So it's actually sort of interesting, what keeps things from going haywire. Anyway, what happened was that the Antarctica froze over for about 14 million years ago and it cooled down everywhere. And then at that time serious Ice Ages started up. Here is a picture from around the middle of the last one. This is the coldest part of the last Ice Age. So you see that lot more ice in Antarctica, glaciers covering lot of Europe and North America, and since then ice has melted and this is all happening and sometime you are little slippery there. So if you think about it this way, you will see that the earth is really cold right now and it's very unusually chilly and so you might ask yourself, well gee, maybe a little global warming would be just the thing. And so it's a good question, I mean, I think it really needs to be addressed so what is wrong with global warming, really? And the answer though it's fairly simple. The answer is, its happening way too fast. It's happening shockingly fast. It's not being warmer, being cold that kills off animals and plants. It's that - really the change in temperature. The temperature changes faster than they are able to adapt to, that's the problem. And this is the scariest graph of all as far as I am concerned. This is a graph of carbon dioxide concentration in the earth's atmosphere over the last few ice ages. The carbon dioxide really closely tracks the temperature. Unfortunately, I don't have both graphs here the temperature and the carbon dioxide. But they really match, and so the last Ice Age was here and the Ice Age before that, and you can see that the amount of carbon dioxide during this whole period of Ice Ages has been oscillating in this band here until 1860 when it shot up almost vertically and its now about, well, its significantly higher than any of this recent history, and that's because of the manmade carbon dioxide and you really need to zoom in to this little last 1000 years to begin to appreciate how its how its shot up, its really just shot up in the last 150 years. So what's happening is that, we have this period of Ice Ages alternating with warm spells for quite a while, and then, wham right now things are completely changing, it's a whole new ballgame. So what's happening is that species of lots of animals and plants are trying to stay in the temperature zones that they are used to and so the ones north of the equator are all moving north. They have done a survey of about 1500 species and they found that on average since 1950 they have been moving north six kilometers per decade or about 10 miles per decade. So about a mile a year animals are moving and plants are moving north. Of course, that's pretty though for plants to move that fast, if you think of about it. Although - well, you know, they die on one end of their habitat, they start to grow on the other end. But the real problem is they can't keep up, because since 1975, the actual temperature bands have been moving much faster than that. The temperature that is if you keep a line of constant, of equal temperature and see how it marches north, these things warm up. They have been moving north at four kilometers per year or about, I guess, that means six miles a year. So there is no way that most animal and plant species can move that fast, especially of course, you have to imagine that at the same time you have people with like cookie cutters ripping away their habitat all over the place, making it harder for them to move around. I don't know if anyone even mention the idea of building a wall between us and Mexico, and how that will effect the flow of animal life. I don't think they are planning to lead the animals through. And you see this is just the beginning. So this is - I am talking about now, but you see that's - we have seen this one degree warming since 1900 roughly about 0.8 degrees, but that's just the beginning. Here are all sorts of different people's projections for what's going to happen in the future. But you can see even though the more conservative ones would be suggesting about two degrees more warming in the next century or possibly quite a bit more like five. So what we have seen is climate moving along and then vroom!, something happening much faster than life forms can adapt to. That's the problem with global warming from the point of view of the ecosystem as opposed to just people. So it seems quite likely, they were entering a whole new geological era and in fact people have given a name to it the Anthropocene, that is it quite possible that the Ice Ages are done with now and they were entering a new period of extreme warming and as with other changes of from one geological period to another we will probably see a lot of extinction. So in fact just around now in the last few years we passed the temperature record that was set 120,000 years ago. So I don't know we should have a party but we but we are - so the last time its been this warm was before the end of the last Ice Age and if we just warm up one more degree which will probably happen in another 50 years the earth would be the hottest its been in 1.35 million years, that's when the Ice Ages began. So in 2050, we will have we will be out of the Ice Ages and into some completely new territory so to speak. And people have done a lot of different projections on what that's going to mean for animals and plants and they estimate something like between 15 to 40 percent of all species are going to get killed off and that's due to the warming of course there is also lots of other things going on so for example as you know lots of things are going on. 90 percent of large fishes have been killed off in the ocean over the last 100 years, we are seeing major die off in birds species in America and we are seeing lot of amphibian species going extinct about a 150 in the last 50 years - all sorts of different things for all sorts of different reasons in this global warming is just one part of the whole story. So to understand what this really means for the world we have to go back even further in time and look at what are called the mass extinction events that is the times when significant fractions of the species on the planet of the earth have been wiped out. So I have just mentioned one of those the end of the dinosaurs but there are others and here is a picture of them. So here is a graph where the present is over on the left-hand side so time is going this way. And it's a graph of extinctions. These blue spikes are the mass extinction events. Its telling you what percent not of species what extinct but of general went extinct. So genera is the plural of genus so where Homo sapiens so sapiens is our species and then homo is the genus so there is also like Homo Neanderthalensis, Homo Australopithecus all that - all those different variance of genus homo are form one genus and that's what - what's been counted here. So the idea is that just species goes extinct there will be some other species that are pretty similar that could then later on adapt and branch out to fill the - any niche that was left but if a genus is gone that's more significant. So at the end of the age of the dinosaurs, 30% of genera went extinct. At the end of the Eocene that's when the temperature suddenly dropped - I will just zip back there for you. So here - that was a major extinction event and you can see that this particular one is probably due to this - the drastic cooling. I am not saying that all extinction events are due to temperature change of course at the end of the dinosaur or something completely different but that one is probably due to the sudden cooling and so that end of the Eocene extinction event was the biggest one since the end of the dinosaurs. So 10% of genera went extinct. And the current one is not plotted on here on purpose because it's underway we don't know what's going to happen. The real big one was at the end of the Permian the Permian Triassic extinction was the biggest of all as far as we can tell about - as you can see here about 50 or 45 or 50% of genera went extinct. There is a book that's available out in the lobby called "When the Earth Nearly Died" I think something like that which is about that and no one is quite sure why it happened. The one possibility is that it is that its known there are huge amounts of volcanic eruptions then there were some kind of I guess major tectonic event and it's possible that there was a huge burst of global warming due to the release of lot of carbon dioxide from volcanoes but there are other competing theories for that. And you can see that there were other major ones earlier on. This yellow curve is sort of interesting that's the sort of average curve of extinctions and you can see that on average the severity of extinctions has been going down which may actually mean that this idea of survival of the fittest or evolution is a kind of advance has really has something to it maybe that that life is just getting better at adapting to changes overall. Let's see. So what's going to stop things? Well, luckily, we will run out of oil - yeah. So, different people predict that what happened at different times, don't worry I am not running for office. So, here are lots of different projections, you see that most of them predict that peak oil usage sometime around in 2025 or so this is in millions of barrels a day. So, right now when this chart was compiled, its 85 million barrels of oil burned a day, it may go up to about 120 or so, you know, it will start going back down. Just so you get a sense of how much agreement there is on this - that red curve there is prepared by Exxon, where as the green curve there is prepared by British Petroleum, which is - I guess, green is the right color for them. There - as oil companies go they are green. But the point is that - for point of view of human politics, it may make a huge big difference whether the oil more or less runs out around 2075 or 2125 but from the point of the view of the earth as a whole, its not that big a deal. I guess it may effect how many species are killed off. But the point is it's going to end pretty soon. And so, you could take heart from this and say, well, you know, we are going to be miserable, of course, but at least those rise in the carbon dioxide concentration of the earths atmosphere is going to stop fairly soon, and then, hopefully it will something, it will level off in time that we don't completely send the climate totally out of whack from what we are used to. But that's an open question. So the question is what can we burn next? And we have there is a lot of stuff to burn. So there are three trillion barrels of oil left to burn. There is just one trillion barrels of natural gas equivalent - these are converted to be the equivalent amount of energy. So there is less natural gas. There is bit more coal. 4.5 trillion barrels worth of coal. There is about the same amount of tar sands, 4.3 billion trillion barrels. Tar sand is this goopy, tarry stuff that with a lot of work you can extract the oil. But the worst thing all of those utterly are 72,000 trillion barrels of stuff called methane hydrates. So I am sure you all hear about methane hydrates. No, you never hear about methane hydrates. What are the methane hydrates? Well, in the ocean - in the northern latitudes on the seafloor there is this weird stuff, that's a mixture of ice and methane, its ice molecules that have little methane molecules fit into the empty space as you know ice is lighter than water, it's a very loose arrangement of water molecules and there is enough room to pop a methane in there and you get this funny mix called methane hydrate. If you dig up a piece of that and bring it up to the up into the air, its unstable and the methane goes, whoosh and fizzes out. You, apparently you can see on the webs or movies of what it actually looks like. But there is a bunch of that stuff down there and of course people are scheming for how to dig it up and burn it. And that is precisely what you should do if you want to first of all keep the carbon burning economy going and second of all if you want to make global warming that's approximately 10,000 times worse than what we see now. Methane Hydrates are pretty interesting, because there is so much of them and they are sort of mysterious. There are times when they have impacted the climate and I should just point out one. I should go back a bit. So see what we are facing now is this funny thing of a sudden spike of temperature, very rapid spike of temperature and so it's interesting to look around for other comparable events and see what happened to the world under these spikes. So if you look at this graph, you will look at this thing here blip, see that little thing. That's called the Paleocene-Eocene Thermal Maximum or PETM. It's not the biggest change in temperature but it's a very sudden change of about two degrees that lasted for just about a thousand years and it was a warming spike and people wonder what caused it and what they think caused it was a methane burp. A methane burp in case is when the methane hydrates on the ocean floor somehow gets destabilized and emit all this methane that's down there. Now methane is an even more of a greenhouse gas than carbon dioxide which is why in fact people are seriously concerned about farting cows. I am serious. Farting cows are a substantial contributor to global warming but this massive release of methane from methane hydrates was even more important by far and they noticed that there was significant extinctions at the time. I guess, 30 percent of foraminifera had died out at the time. Foraminifera or forams are little critters that float around in the sea that have a calcium shell that eventually turn into lime stone when they die and fall to the bottom. So when you look at lime stone that's largely foraminifera and other things like Diatoms. So what it meant was that there was a sudden change in water temperature during that period that killed off lots of those guys. There have been probably other extinctions that were caused by massive release of methane and that's the alternate theory for that big die off. I mentioned, the - here the extinction at the end of the Permian its known there was a huge burst in warming. So the two competing theories are that carbon dioxide from volcanoes or methane from a methane burp is very responsible and people are arguing about it now. Anyway if you want to be really paranoid you can make up scenarios where people digging for methane hydrates causes a methane burp. I don't know how likely that is. But if that doesn't happen well maybe we will just burnt it and turn it into carbon dioxide and it will have more or less the same effect. So the question really is can we resist trying to keep going our normal course of burning and try to switch over to some other sources of energy. And of course, there are large industries devoted to keeping business as usual. I just liked this - instance here, so here is a note placed by Philip Cooney who is the Chief of Staff of the White House Council on environment quality in 2002. This is a scientific report that came to his desk about global warming, that was prepared by various environmental agencies and here he is watering it down saying instead of the earth is undergoing a period of relatively rapid change, changes that the earth maybe undergoing a period of relatively rapid change and so this is an example of how various political forces are pushing us away from realizing the significance of what's going on. When these notes were discovered, Philip Cooney suddenly decided he needed to spend more time with his family which apparently was Exxon. He said he wanted to see his family and I guess he saw them for a while but then he went to work for Exxon. So in fact as, you know, Exxon's has a major role in setting up this network of think tanks that tried to down play the importance of global warming. And so the question is can we sort of see through the baloney to see what's really going on in time, to have a any effect. It may well be already too late to really to have an effect. So we have to contemplate the possibility of a mass extinction. In the long run you don't have to worry too much about mass extinctions whereby the long run, now I mean, this maybe periods of say 10 million years or so. So a mass extinction event is a pretty sad thing, here is a picture of the sea floor before the biggest mass extinction event and afterwards. You can see the complete impoverishment of the biodiversity that happened then. But then after tens of millions of years it bounced back and it became even more interesting. So life does have this amazing way of bouncing back from these major disasters and it even seems to get more interesting each time. So from that point of view which is a very sort of cosmic or at least long term terrestrial perspective we don't really need to worry, we may die out but its very unlikely that we are going to kill off all life on earth and even if we do, really there is nothing to worry about, there is lots more where that came from. There are about a 100 billion stars in this galaxy, if one of them just manages to have life for a while and it fizzles, I am sure there is plenty of interesting stuff happening elsewhere, since I tend to think on large scales, that's usually how I sort of calm myself down after reading the newspapers. You know, so something happened over there. I am actually usually more interested in what's happening over there. There is a very large black hole there, that's sort of more interesting to me and really the galaxy isn't such a big deal. There are 10 billion of them in the observable universe. The observable universe means not just what we can see now but what we could ever see, in other words if you look back into time to the big bang you see 10 billion galaxies. So that means that there are about 10 to the 21 stars in the universe of which ours is just one. So on the grand scale of things it doesn't really matter to anyone what happens except, well for us, of course. So we are sort of on our own here, I think, and the question is can we zoom out in time. Thanks.