Dan Britt - Orbits and Ice Ages: The History of Climate

foreign thank you very much i hardly recognize myself with these introductions um the reason i'm doing this talk because climate is not my day job my day job is asteroids and meteorites and and comets but what i did as an undergraduate because i went i i went through and had a normal college career and then in my 30s i had an early midlife crisis and went totally bonkers and decided to go back to school and become a scientist and so i had to start all over again because i i went into the graduate advisor at the university of washington and said i want to go to graduate school in in geology and he said well have you ever taken a geology course so well no you don't need one for economics silly guy but i know this is what i want to do that's another story as to how i arrived at that um but i went back in in my in my early 30s and as an undergraduate i needed to eat and so i got a job in the stable isotope lab at the university of washington and this is a this you know i've been a scientist for a long time since and i have never been in like such an elaborate central casting science lab as i walked into that day when i applied for a job because it was a room about twice the size of this room and it was covered for the ceiling on all the walls and down the center with glass tubing and beakers and bunsen burners and stuff bubbling over and and and and big machines with lots of flashing lights it was it was a science lab from central casting and what they did was amongst other things they measured the isotopic ratios of ice cores and that's what i did for three years and for two for for three hours a day three days a week i would stand in a freezer and cut up ice cores and then go measure them in a mass spectrometer you know and and here i was i you know middle-aged undergraduate no experience in science and i said i want a job running a mass spectrometer and for some reason they let me do it and so a lot of the data i'm going to show you today i actually took which is kind of cool because i was at i attend scientific meetings later and years later i was sitting in a meeting and some of the data i took flashed up on the screen and some and in the question and answer period somebody got up and said i don't believe that data it looked like they made a bunch of mistakes and so i got up right behind him and i said i took that data and we noticed the trends that you notice because we're not idiots but we checked it over three times and that's reality just because you can't figure out reality that's not reality's problem that's your problem and i'll be happy to discuss this with you outside i'm kind of i believe in kind of a muscular science i've always wanted to do that anyway so i'm going to show you a bunch of stuff the problem is with climate there's a lot of things going on this is not soundbite science so i'm going to tell you a lot of complicated stuff i'll try to be entertaining some of it will be boring i apologize in advance but with climate you hear a lot of a lot of stuff you see greenhouse gases are warming the globe sunspots actually cause the warming these are actually the sunspots from tuesday i doubt you could there's a there's a a noaa site that you can go to and get the latest sunspot data that's the latest sunspot data that we're in ice age that the glaciers are melting sea level is rising co2 is natural co2 was a lot higher in the past co2 was a lot lower in the past that the earth is a lot warmer in the past the earth was a lot colder in the past and the problem is that everything here is true sound confusing well no it's not actually it's quite reasonable the thing is we actually know quite a bit about past climates this is what i did in this laboratory now i can go into excruciating mind-numbing detail as to how we know it in the physics behind it i will spare you that if you insist i will tell you okay but what this does is it tells us for the we know we know the earth's climate history pretty damn well for the last half billion years for very you know after that it gets a little tricky but for the last half billion years and that's not bad and so we can actually look at what's normal for earth and the question is what is normal for earth is today's climate normal for earth now actually this i like this picture because this is this is the same location um there's about 60 years difference here you can see the bathtub ring uh left by the glacier right there see right there so also what i'm talking about is climate and climate is easy i read climate out of the geologic record predicting weather is actually tough that's way beyond my abilities because that is hard you know there's a reason why people don't forecast hurricane tracks more than five days in advance because that's really really hard i don't do weather i do climate and when i talk about climate i talk about long-term climate climate in geologic terms and in geologic terms you can actually find out the effects because this this climate experiment has been done over and over again in earth history and all you have to do is go back and read the rocks and that's what i do addressing the question what is normal all you need to do is go back and look at the geologic record and how things change with changes in the various climate parameters all you have to do is go back and you can read the path climates from the rocks and the chemistry are laid down in those periods and the nice thing is that people that are a lot smarter than i have have puzzled this out and a lot uh you know a lot have a lot higher tolerance for boredom and so they've done this over the last half billion years and we know this pretty well about as well you know remember science is tentative science we're always groping for answers and testing these answers so you know we know that so the the there are various grades of how well you know things this is a pretty high grade we know this pretty well and so what's normal for climate this is phanerozoic phanerozoic is what you live in today that's the period when you have like complex critters we are here at xero in the neogene go back a half billion years and the first thing you see is that it is about as cold right now as it has ever been in the last half billion years we are actually in an extraordinarily cold period we are in an ice age today we're in a relatively warm period of an extremely cold period oh i didn't say this was going to be easy this is this is you know reality is just i'm not going to sugarcoat reality this is reality and so we're very cold back during the cretaceous the k means cretaceous scientists don't spell well um it was extremely hot but that but nor but average for earth is a lot hotter than it is today but what you should take from take away from this slide is there's nothing normal about climate climate varies a lot and it varies a lot for very good reasons which we can figure out and which we will figure out tonight but what were things like in the cretaceous cretaceous with a c back in the mid cretaceous this is the temperature profile by latitude we are at we are about right there um about 30 degrees so actually the climate for the latitude of pensacola was not all that much different in the cretaceous than it is right now it's pretty warm not unbearably warm because you know with a little bit of air conditioning it's very pleasant to live in in pensacola but it's much different than the present day and the difference is not in the low latitudes it's in the high latitudes because in the cretaceous nowhere on earth even at the poles was it on average below freezing if you can imagine that in the cretaceous you had a temperature profile that essentially made middle uh uh what you consider temperate climates going all the way to the arctic circle so in their cretaceous you had warm adaptive vegetation and warm adapted critters at the arctic circle you can fight you can go to the arctic circle today in canada and find breadfruit tree fossils fossils of turtles and crocodiles and there was no continental glaciation anywhere not even the poles not in antarctica you had tropical conditions to 40 degrees north-south latitude so that's the same latitude as new york can you imagine the climate of key west in new york city coral reefs growing off of long island no hard freezes in ohio can you imagine ohio with art without hard freezes people would want to live there all year round i could i i can say this about ohio because i've lived there um i i don't want to insult ohio ohio is a wonderful place to live but they have hard winters this is you would have essentially the the the climate that you enjoy in pensacola in ohio why so much warmer well back then co2 was about 1700 parts per million now this doesn't mean a thing to you right now you will know these numbers at the end of this lecture in great detail because i will keep repeating them to you that's six times the pre-industrial levels of co2 that we enjoy we enjoy in the the recent period and remember when i talk about recent i'm talking as a geologist so this is over geologic time i consider the recent period the last 10 000 years this is just my quirk so when i talk about the old days you know the old days are you know 70 million years ago uh you know the other the other uh quirk is that i just don't i don't look i'm not interested in thing scientifically i just don't don't have interest in things that haven't been dead for half a billion years or so but now that's another story anyway so why so much level much higher co2 a much different ocean circulation in continental locations but there was a downside to all of this so basically this would be in the cretaceous versus now this would be the same location this kind of vegetation which today it looks like that the downside of course is that no continental glaciation means a much higher sea level something like 150 to 200 meters higher sea level so the downside is that st louis is a seaport there is no florida above above the waves all of florida is a shallow part of the shallow sea um almost all the coastal areas are inundated uh you know all the middle east is mostly under water you know so there are good parts and bad parts like anything else so it's much warmer you can live in ohio quite pleasantly except you just don't get to live in florida now you ask well that is that normal well what is normal sea level we are here at xero if any of you work in the oil industry you might recognize what is called a veil curve this came out of the oil industry after after spending literally billions of dollars of research because this is how you find oil the way you get oil is is what geologists call a succession of transgressions and regressions of sea level which trap the right sort of critters and right sort of sediment underneath the right sort of layers of stuff in order to make oil and that's very much a function of sea level so this is actually pretty damn good data and because you know it you make billions and billions of dollars if it's exact so that's a good reason it's not just because hey you get tenure or something you make vast amounts of money and they fire you if you screw up um yeah so and also you see the spikiness here that's actually real sea level is actually highly variable and not just from melting glaciers it turns out that the mid-ocean ridges where most of the volcanism occurs this plate tectonics stuff the plates actually move around they actually vary quite a bit and when the when the mid-ocean ridges decide to crank up and expand and and and create plate faster they actually expand if they expand there's no other place for the water to go except into your homes and gardens so and this occurs on you know this is geologic time again so it occurs on like million year time scale so you know don't go out and sell your waterfront property um but you know this is you have to recognize that this is the sort of thing that happens so let's talk about the recent climate you know and the recent climate is like the last 50 million years or so um back in the usain it was pretty warm and then what's been happening over the last 50 million years is a slow deterioration and but steady deterioration the climate you actually you actually didn't get antarctic glaciation until about 35 million years ago and that it it glaciated and thought out and re-glaciated and since it's been re-glaciated over the last about 12 million years there's this been this very steady very sharp drop in the average temperature of the globe why is this happening well before i go into that i just want to say that the uh this the this if you just look at the last five million years this trend is continuing it's been very steady and what happens is that it's climaxed in a series of glaciations in the last million years these glaciations have greatly intensified and so you're getting bigger swings in climate as as it gets colder and so what we're we're living in is a relatively warm period of what is an incredibly cold period in earth history so this is the last 400 000 years and i actually took some of this data we are here and what you find is for the last 400 000 years there have only been four periods when it was this warm and these periods usually last three or four thousand years does that make you worried i have made me worried when i took this data it's okay though i'll show you why but anyway we're here and we're actually in the most extraordinary uh long interglacial this is these are the warm periods are called interglacials and these things are typical the glacial periods are are characterized by this stepwise deterioration and climate down to a glacial maximum now what are glacial maximums like the last glacial maximum was eighteen thousand years ago um last glacial maximum you had a mile thick glacier mild thick ice in new york city berlin and london you had a mile of ice over seattle you had continuous sea ice down to cape hatteras in the winter you imagine your condo and cape hatteras in the winter with continuous sea ice continuous sea ice down down to baja california well i've been to baja california i've gone in the ocean there it's cold i can see why it would have sea ice there but still that is kind of extreme but we have excellent geologic evidence that that's what happened and you had continuous summer sea ice all the way along the continents how do we know this well once again you can go look at the the g a lot you can read this out of the geologic record you can look for what are called geological striations and don't believe me go and look for yourself this particular location is the the bedrock in central park and you can see grooves cut in it from the rocks dragged on the bottom of the glacier you can figure out how thick and what direction the glacier was moving from the depth of the grooves this particular one is across the street from the american museum in natural history as you go through the iron gate turn to the right go and look for yourself same thing with the with the crocodile turtle and breadfruit fossils in the canadian arctic you can go to these fossil locations and you can look for yourself i urge you to do that watch out for the polar bears so what caused the ice age well blame china and india seriously what's happened is that we actually live in an extraordinary i keep saying this we live in an extraordinary time in earth history but we do very few times in earth history are you able to walk to the bottom of the stratosphere on a mountain but you can do that in himalayas that is a very rare event you think because you can do it today that it must be normal for earth but no that's very abnormal you look back in the geologic record and you don't get 30 000 foot tall mountains very often this is really unusual and what happened is over the last 20-30 million years india collided with china and created the tibetan plateau an extraordinarily high set of mountains that really when you when you raise stuff up like that and you break up rock like that what you do is you vastly increase rock weathering now i can go into excruciating detail again on the right on the chemistry of rock weathering but the bottom line is that it sucks carbon out of the atmosphere like crazy and that's what happened here we've lost about 80 percent of the carbon that was in the cretaceous atmosphere due to the himalayan rock weathering so you can blame china and india and what happened was this is basically made the climate vulnerable to small changes in solar energy inputs now and these small changes are caused by orbital variations the orbital variations are always there but since you don't have as much greenhouse gas in the atmosphere it makes it more difficult to distribute heat across the planet and if you don't have the greenhouse gases you're not going to distribute the heat into the polar regions and if you drop the solar input to the polar regions you're going to end up getting glaciers and so what happens is that the glaciers are triggered by variations in the earth's orbit the way this works is you know blame kepler and galileo and copernicus the earth is earth's orbit is not a perfect circle you actually are closer to the sun by about five million kilometers in the middle of winter january third did anybody celebrate perihelion on now next year you can celebrate perihelion and it's really easy to remember aphelion is july 4th everybody celebrates appealing nobody celebrates perihely i could never understand that but you get six percent less solar energy at aphelion and afghan happens to be in the summer so the this actually moves around in the orbit and in the seasons it's called procession and so right now summers are a little bit cooler and warmer and winters are a little bit warmer because of the positions and orbits but that changes over time and it can be a fair amount six percent of solar energy is fair amount this is basically a simple idea if you have warm winters you're going to melt all the snow that falls in your really cold if you have warm summers you you melt all the snow that falls in your really cold winters if you have cold summers that can allow snow to accumulate in the right latitude range and also warmer winters tend to produce more snow and i think we're starting to experi last year was it was a good example of that in the northeast where it was relatively warm but it was really really snowy the guy who puzzled this all out was a serbian mathematics professor called milenkovic and i'm i actually have there's a serbian graduate student in our group and she just despairs of my pronunciation so i apologize in advance that i misproduced mispronounced his name but this was back in the back in the early days of the the 19 the 20th century this was big science the uh the question of why there were ice ages because you could see abundant geological evidence that there were at least four big ice ages four big glaciations in europe and in north america and and the the question the burning question was why and this guy decided that that um the way to figure this out was to look at variations in the solar flux at high latitudes and you can vary that solar flux at at 65 degrees north latitude by as much as 25 but the way to prove this was that you had to do a bunch of spherical trig and figure this out over the last quarter million years now a smart student with an excel spreadsheet can do this in about two weeks back then in the old days astronomical computer was not a machine it was a job description if you wanted to figure out where to point your telescope you needed somebody to to puzzle this out and so astronomical computers were the people that actually figured that told the fat bearded white guy who was the astronomer i can say this being a fat-bearded white guy myself and also astronomer where to do this and typically the staffs were lots of really smart women who graduated from ivy league colleges and you know prestigious women's colleges like holyoke and bryn mawr who couldn't get jobs anyplace else and these guys actually did a lot of the fundamental astronomy in the 19th and 20th century and didn't get any credit for it because of course this guy wouldn't put any of these names on his papers um a major injustice being a fat bearded white astronomer i apologize for that but that's the way it was you know the way the way you figured this out was somebody actually sat down and did the math by hand with a pencil and that's what milenkovic did in 1910 he started working on this and he figured that if he his day job was teaching mathematics at the university of elgrade and he figured that if he when he came home and had dinner and then worked for four hours a day five days a week and took all saturday and worked 10 hours a day and then sunday he would go to church and hang out with his family if he did that he could he could do all the necessary calculations in only 22 years you know this was science back in the old days you know no excel spreadsheets um he well he was lucky and unlucky at the same time because what happened was that world war one hit in 1914 he was he he was a reserve officer in the serbian army he went into the army in 1915 he was captured by the austrians thrown into prison camp and he had a buddy in the in in the hungarian academy of sciences who bailed him out of prison camp and this is a different age i was an air force officer so i think this is really cool back in those days if you were an officer you could give your word your parole and they would let you out of prison camp and you would promise not to you know raise your hand and promise not to fight anymore and then they would let you out of prison camp and you could go off and do your own thing what a civilized concept and so what they did was they paroled him to the reading room of the hungarian academy of sciences and budapest for the rest of world war one and so he was able to work on his stuff ten hours a day seven days a week and he actually got years and years of of work done during that period and he went back and he actually was able to publish in 1925. and what he found was that if you look at these cycles that there's that the orbit of the earth's orbit actually affects the amount of sunlight you get tremendously because there's an eccentricity cycle that goes from about zero um to point uh to six degrees in the uh in the roundness of the orbit there's a tilt cycle that goes from about 24 to 21 and a half degrees and a an index of precision that where you where you are in the orbit when you're closest and farthest from the sun and you can combine all these effects and actually see how much sunlight you get at high latitudes and it turns out that that just lines up with the relative cold and hot in the climate this is more of the data that i took and so there's a hundred thousand year this is hot this is cold this is right now this is a roughly a hundred thousand years ago um that's the last that's the previous interglacial this is the eccentricity cycle 100 000 years there's the precession cycle 23 000 years that's the tilt cycle 41 000 years it lines up these orbital changes absolutely dominated our climate for the last half million years and this and all the other things that you see that you hear about in climate el ninos uh pacific oscillations uh atlantic decadal oscillations all these are in the noise all of that is subsumed in the thickness of the lines you see here because this absolutely dominates this is what creates a mild thick glacier on top of new york city and just because it's a little rainier because of el nino that's in the noise compared to having a mile thick glacier on top of your apartment okay so that's where we are so our climate for the last million years has been characterized by these long periods of terrible glacial conditions glacial conditions like you know tundra in southern france you can go to you can go to southern france i did this last year and go into the nc cave paintings where they have cave paintings of herds of reindeer because that was the scene you know now you've you know it's be bikini-clad women on the beach not reindeer anymore all that is driven by orbital changes so the nice thing is though that you can calculate how these orbits are going to affect climates because this is what absolutely has dominated our climate for the last half million years and we should be able to figure out what the climate should be doing given the solar input and ten thousand years ago it was really warm this is the line you need to look at here because this is summer insulation the the amount of sunlight you're getting at 65 degrees north and it peaked about 10 000 years ago and then has been in decline ever since so what should be happening is we should be dropping into the next ice age climate should be deteriorating things should be getting colder given the solar input the problem is that it hasn't been solar input is dropping but the ice is melting so what's going on and what's going on is is us and greenhouse gases co2 and methane what happened is that our ancestors were smart kids about up until about 8 000 years ago the atmosphere stuck with historic trends but about 8 000 years ago our ancestors invented agriculture started clearing forests when you clear a forest what you do is you it slash and burn you put lots of carbon back in the atmosphere you control the forests with fire very intensive and very carbon intensive sorts of agriculture methane the same way about 5 000 years ago they invented rice cultivation and domesticated livestock nothing is is a better uh methane producer than a herd of beef cattle you can you can also test this for yourself go to a cattle ranch let me know what you think the other thing is rice cultivation i don't know how many of you spend time in rice paddies but rice rice is a is a swamp grass and so what you need are swamps in order to grow rice when you don't have swamps you go create them and if you it and one of the tests here is that you can sort of cruise around um the far east on google earth just to see how extensive the rice cultivation is prove for yourself this these these terraces are 3 000 years old in the philippines basically once you use up the swampy terrain you got to start terracing or you starve and terracing dates back about 5000 years the limiting factor here is water if you have a source of water you can make terraces i really like this picture because essentially it looks like a topo map but it's not it's just um this was a book i found in the library it was done by claire chennault's um photo reconnaissance officer during the world war ii period worked for the flying tigers and so he has all these great pictures of china the way it used to be you know these days they you know they run super highways through this but uh essentially everything that had a everything that could be terrorist was terrorist and so human input to the atmosphere started a long time ago it's not just us in the industrial age basically in the pre-industrial age you started out with about 260 parts per million co2 and human activity stopped the decline of co2 and and methane in the atmosphere and cranked it up to about 280 parts per million essentially putting carbon gigatons billions of tons a gigaton is a billion tons of carbon into the atmosphere so about 80 gigatons of carbon that's equivalent to about 10 percent of the biomass but that's about right for the forest clearing that happened in the pre-industrial age the problem is that you your your your solar input is still dropping and so even though you're tossing in more carbon from burning more forests and and and and domesticating more livestock and and making more rice patties there's a there's a point of diminishing returns and so actually things started to get colder back in the middle ages simply because you couldn't keep up what we did then was we tapped a new reservoir we figured out how to get into fossil fuels and use those the whole pre-industrial atmosphere had about 600 gigatons of carbon in it what we do now is we add about nine gigatons a year from fossil fuel almost all from fossil fuels there's a tiny little bit this is a this is cement production right here all the rest of this is is uh fossil fuels people say well you know what about volcanoes the entire on average the entire volcanic input into the atmosphere is two tenths of a gigaton of carbon per year people say well what about mount pinatubo mount this is mount pinatubo notice the guy with the water buffalo plowing who's ignoring the largest eruption in the last 150 years that's clark field in the background since this is since this is a a flyer town probably a few of you flown into clark field uh clark field was a little bit the worst for wear after this but anyway the mount pinatubo eruption they're not really sure but this is in the noise .08 gigatons of carbon is a maximum estimate that's in the noise the biggest natural input net input to the the atmosphere is volcanism and that's 45 times lower than the human input from fossil fuels every year 45 times so now remember i've been talking thousands of years and hundreds of thousands of years um and these are big trends so let's talk about the noise because you and i live in the noise i've been talking about geologic scales you and i live at human scales and so year to year variation or decadal variation means a lot within the within the big trends there are a lot of short-term effects things like sun spots pacific decatal oscillations southern oscillation volcanic eruptions all sorts of other things too and all of these have an effect on short-term climate because this spikiness is real that's the no that's the noise that i said was that was the noise i was talking about in these big swings but remember when we're talking about big swings this is this is a swing down into the ice age it goes about another another uh uh six degrees down here so that's what i was that's what i'm talking about with the big glacial swings so we live up here in these spiky in the spiky area let's pretend and i don't like to do climate modeling because that's really complicated i like this model because it's fairly simple i'll just show you this to show that it's possible to explain short-term variation let's let's let's pretend that short-term climate is driven by four things the sunspot cycle because sunspots do affect solar irradiance and the amount of watts per square meter that the sun dumps on the earth so you get a 11-year cycle where you get a little more radiance and a little less and the it affects it on the on the order of of less than a tenth of a degree c like half a tenth of a degree c then you get volcanic aerosols mount pinatubo blew up and threw a lot of gunk into the upper atmosphere and that actually cooled things down quite a bit that's mount pinatubo right there and um then you get the europeans you get the um el nino southern oscillation el nino actually does change the energy balance because it's a big lump of warm water that sloshes around the pacific in the simplest sense and once again we can do this more complicated but if you sum all of these things and say that's what drives short-term climate with this anthropogenic influence that is dumping more carbon in the atmosphere you can actually model the black line as the instrumental surface temperature record or as i like to call it reality you can actually model reality pretty damn well not bad though fit as 87. the thing is though that we're just coming out of a very low sunspot cycle actually historical uh in the last 50 or 60 years of historically low sunspot cycle so things were actually slightly cooler because of those sunspots but we're going into solar maximum right now so sunspot cycle is cranking up as a result what's going to happen i will predict is for the next four or five years you're going to have a succession of extremely hot years sad but true and so far it's it's it's proven uh uh the average temperature records have been proven that that's that's what's happening so of course people say well is the temperature record wrong well it could be uh but it turns out that you can don't have to rely on instrumental records you can do things like you can measure temperatures directly from boreholes because there's actually a temperature record that's preserved in the in the the shallow crust all of these show strong warming in the last hundred years uh you can look at the average monthly sea ice extent this is updated to this year and it's declining you can look at alaska growing seasons they're getting progressively longer you can look at um low elevation glaciers in in alaska the one i showed you um was muir glacier that's not the only one mccarthy glacier i love these guys because what they did was that they went through and got a whole bunch of old national geographic style pictures of glaciers in lowland alaska and then went to the exact same place and took another picture i love this and i've got a big collection i'll bore you with a few of them because i just love these things northwest glacier northwest glacier really got hammered there it is way back up there point is that you can look at a glacial mass balance and it's just dropping off a cliff um trends i was born in 1950 when i first drew breath the co2 level was 310 parts per million in this room today it is about 390 parts per million back in 1950 we were putting out 1.3 gigatons per year today we're putting out about nine gigatons a year you know you just have to be in los angeles and look at it at a crowded freeway and say how can you believe that doesn't have an effect of course it has an effect the other effect is when i went to graduate school i was in my mid-30s and so when i walked into brown university i was the oldest graduate student at brown university i ended up sitting next to a guy who was the second oldest graduate student at brown university i was 35 he was 34. a guy named vadon from people's republic of china i said hey you know 34 that's pretty damn old for a chinese graduate student they said well yeah i went to graduate school back in the the regular time but then the cultural revolution hit and they sent me into exile and tibet for nine years so wow that's a really good excuse they looked at me and said what's your excuse you know it's like the 70s i lived them i don't remember them um but that was 1985. and the chinese which conti it's you know this is like a quarter to a third of the world's population they did us this huge favor during most of my lifetime you know this is a a hugely populous hugely talented uh hugely smart ambitious group of people who decided to make themselves just dirt grinding poor for decade after decade after decade and they didn't compete with us for resources or anything they just wanted to be poor because you know that was a that was their policy and so they're they're this is the gdp of the the people's republic and then about unfortunately um mouse tongue died massetong was a huge favor for us believe me in terms of carbon dioxide they decided oh well why should we be poor anymore let's go make stuff and sell it and become rich and boom this one only goes to 2004. the the actual gdp is uh uh 40 47 uh 160 billion yard you know it's like above the second floor now on this plot and all these guys want the same sort of thing we want you know they want to live a middle-class lifestyle they want to drive a car they want to have freeways and they want to have power that works 24 hours a day so they can run their air conditioning because believe me it's just as miserable in shanghai as it is in pensacola during the summer because you guys are at the same latitude and so they're going to want to they're going to want to they're they're producing a a gigawatt-sized coal-fired power plant every two weeks in china so what do you think that's going to do to the carbon input okay so some answers yes we're in an ice age if you look back over the last half billion years continental glaciation is very unusual very unusual does the climate vary of course it varies it varies constantly is the current climate normal now normal for miami is to be under 80 meters of water normal is not to have a florida is the planet warming because of human action i as a scientist i am just floored that this is this is this is a political thing for political discussion of course it's warming we are well into the next milenkovic cycle we should be getting advances in glaciation and we're not because we've been smart enough to this is called geoengineering we've been smart enough to change the atmospheric chemistry and redistribute the heat into the high northern latitudes and make up for this solar insulation that we were not getting human action over my lifetime has increased atmospheric co2 by 25 percent and stopped the molecule cycle in its tracks but we have to recognize what we're doing the downside of this is that if you look in earth history and you have high levels of co2 high levels of greenhouse gases you don't have continental glaciation if you don't have continental glaciation you don't have miami so the bottom line here is do you like sea level where it is yes or no if you don't care then we're done talking you know go and drive your hummer now um as i tell my class this is not my problem i'm going to be dead before this is this is going to be a serious problem this is this is my children's problem in their children's problem you can really you can expect sea level rise of between about two and a half to six and a half feet over the next by two thousand over the next 90 years most of that is gonna it's going to be non-linear so most of it's going to occur toward the end of the century the unknown here is the dynamics of of of uh glacial collapse now luckily uh in greenland greenland is kind of bowl shaped so most of the glaciers are surrounded by by mountains and there are only a few exits and so it won't it probably won't collapse really catastrophically you can see things in the geologic past where where you have catastrophic glacial collapse the laurentide ice sheet in canada catastrophically collapsed and melted if any of you have ever been to quebec or montreal you can see the st lawrence valley if you look at the saints the lawrence valley the st lawrence occupies this little tiny strip on this big huge flat plain of a valley and you can see mountains off in the distance one way and mountains off in the distance the other that whole thing used to be a solid river when the laurentide ice sheet collapsed and what happened was over a thousand years you increased sea level by 30 meters so you can get really rapid sea level increase so do you like sea level because what's happened is that we've already gotten to a level where the greenland ice sheet is in disequilibrium with the co2 level in the atmosphere it's going to melt the question is how fast and the we're working on that we don't know quite yet but this is going to be a problem for future generations my students then say oh thanks a lot you know i said well hey you know i'm just passing it along you know my father left me the cold war his father left him world war ii you know that's what generations do they didn't appreciate that but what the hell so anyway just to give you a little bit of perspective um we are here so you know one meter is no big deal two meters um not so good for the keys you know but then again you know this is you can see why the florida chamber of commerce hates this you know ask yourself what percentage of the assessed valuation of florida is within 10 feet of sea level so anyway i will leave you with this happy thought thank you very much and i will take questions yes ma'am thank you for putting the bell on the cat oh vote i know other people have been doing it too well you know the reality is is is a lot of fun and the canaries have been dying in the mines and i'm thinking of the southern hemisphere uh especially the droughts the dying of cattle yeah the dying of people are they not feeling it before we are well the the problem is i look at this as a geologist and so the the i hate to be to sound um unsympathetic but the average age of a species is about three million years in geologic times so you get extinctions all the time and you can you can argue till you're blue in the face if this extinction or that drought is caused by global warming because that's a modeling problem and it it doesn't have a definite answer if you look in the geologic record what you can read out is that sea level is correlated with co2 and so this is what i can definitely point to as solid evidence yeah i agree with you that is that droughts changing climate conditions more rapid extinctions are all part of the all part of the uh the equation but you can't really point it's sort of like smoking and and and lung cancer you can't say well you know that's the smoking gun right there this is a smoking gun that i know about and also i'm a rock guy so this is what i know about more questions over here thank you very much for an engaging lecture pensacola was blessed uh about a month ago with a speaker named john l casey who's written a book called cold sun and his premise is that there's a 206 year cycle and like you mentioned there's a we're into the phrasing end of and he says it's actually some kind of a sun hibernation going forward do you know anything about any uh sun nation yeah the there's a you get you get a variation in the sunspot cycle and there was a period called the monder minimum where basically you had no sunspots and so that makes things a bit colder that doesn't make things anywhere near cold enough to do to affect these glacial cycles as as i said that sort of thing is in the noise whether the there's actually this 200 odd year solar cycle is pretty speculative stuff and i've seen evidence for and i've seen pretty strong evidence against so it might be but it's in the noise yes sir let me ask you to combine two areas of your expertise okay i have been reading that the polar glaciers on mars are actually shrinking and i don't know if that's true or not but can you use mars as a model you know absent all the anthropogenic effects and just look at some of the the major effects of solar radiance and the global mechanics and so forth and i don't know what you'd have to do maybe have bore holes on mars or something but you know that's not beyond well actually there's a quick answer for that mars is actually more variable in its insulation properties than the earth is and so people have done this work and mars varies so much that that you you actually can change the tilt to about 45 or 50 degrees and when that happens the polar caps melt put all that put lots of carbon in the atmosphere and you increase atmospheric pressure by a factor of five so people have thought that during those periods you might have enough atmospheric pressure to have like you know bacteria and critters and things and that's one thing that nasa is looking for so yeah we've applied this to mars and that it does work and mars is actually kind of in the depths of its ice age right now yeah wow wait for the wait for the microphone loved your speech thank you thank you got a lot out of it but i need to think this through um we can say this but there is no proof that that's going to happen we can we can go through the math we can do all the scientific evidence we can but show me the numbers you showed numbers and i appreciate that i can make pretty graphs i don't think that's going to happen okay it's that's fine with me see um i don't do any mathematical modeling what i do is i look at past epics and earth history where you've had elevated co2 when you have elevated co2 you have higher higher sea levels and you can you can you can look do the milenkovic modeling fairly easily and there's a number of sites that do that for you so you know take a look at it yourself as i say in these in these uh past uh climate epics don't believe me go and you can go and look at these things yourself you know one of the things about scientists is we don't believe in theories we observe them and so we're always constantly testing them let's thank our speaker thank you you

Channel: TheIHMC

Views: 859,008

Keywords: Dan, Britt, Florida, Institute, for, Human, and, Machine, Cognition, 2011, Award, winning, Evening, Lecture, Series

Id: Yze1YAz_LYM

Length: 55min 49sec (3349 seconds)

Published: Wed Feb 08 2012