welcome to the science for the public lecture series science for the public is an organization committed to bringing science information and issues to the general public this is our website for our program to analyze natural climate cycles over centuries to compare that past history with the present rapid change which is largely the product of human activity our guest tonight investigates climate cycles over millions of years and one of the best sources of that record as he's about to explain is speedily of them the geochemical deposits in arctic caves we learn how these natural archives are created and how scientists analyze that unique information jeremy shaken is an assistant professor in the department of earth and environmental sciences at boston college he received his ph d in geology from oregon state university in twenty ten and then was supposed toral fellow at boston university woods hole oceanographic institution harvard university and lamont doherty earth observatory he joined the faculty of boston college and thirteen dr shachtman is a recipient of the e t u climate division outstanding young scientist award dr shackleton's research which focuses on patterns and causes of climate change over the millennia this information is essential to creating accurate climate models and in addition to his work on them as he investigates geochemical data from marine sediments and glaci deposits all in an effort to use ancient geological history to understand better the present and future climate trends we are delighted to welcome dr jeremy shock and welcome  here would you start us off by just reminding us what they call this present condition that we have apparently produce the anthropocene could you just give us a little background please sure so the answer for scene is basically the you know we hear of the cretaceous the drastic these different intervals of geologic history in the past well scientists or scientists have pretty much realized in the last decade or so that we're in a new era of earth history things are different than they used to be they're going to be different for a long time and only in coming you know in one hundred million years we'll look at the rocks on the planet and see different things and i would have bet any other time interval they're going to say something was weird then the weird thing us it's human is we're the biggest force of nature now shaping the whole planet and that's the idea of the answer say so it is us us and also in terms of the climate that we have produced the present situation there is no doubt i think among scientists that humans are the big driver of climate change there's really no doubt over that already is a question where the big thing in the room ok just to make that very clear because we do still have some resistance in certain  corners ok now we've added all this stuff to the atmosphere and i understand it will stay for thousands of years hundreds thousands of years you can't just scoop it out right now no know to as up and it's going to be hanging around for millennia yet you say ok because we just want to make that very clear for people as well in the past since you have reconstructed the ancient history o two was a factor in these melt what do you call the melting and warming cycles or do you see jews greenhouse worlds of the past yeah ok and it was c o two as source different times in the past different sources there's carbon in all sorts of different places on the planet some is locked in oil and coal that we're tapping into today yeah there's other carbon that stored in the deep ocean that can vent out towards the atmosphere there's other big stories of carbon frozen in permafrost in the arctic and if that falls out that can release carbon so it's always carbon moving around and different places it could come from so different times in the past it's come from different places and then of course the big places us digging it up and setting  understand yeah take us back if you will for just a second to like ice ages you have just an awful lot of the earth then and a very deep levels did volcanic activity either in the sea or on land under those fall under the glaciers did that have anything could that have been a factor as well with the c o two the zero two going up and down it could been a factor people are debating a role for that i say in this so the i should say the big place we think the carbon when in and out of was the deep ocean that is the big reservoir that holds carbon that exchanges with the atmosphere on kind of the thousand this y timescale of ice age yes i said you bring up volcanoes that's another kind of the topic these days scientists are thinking about and one of the ideas behind how volcanoes might have played a part is that during the ice age you have huge heavy ice sheets volcanoes than c c four are so i suppose so but in any case the c o two was the major factor is far as these cycles of of melting and freezing t o two was the heating i think it was a big factor in sort of warming the whole world up out of the ice age yeah ok i think that's fair to say ok now you've done lots of different kinds of work and we're will talk about that but take us to the arctic caves i think most of us are completely unfamiliar with speedily of them and the idea of arctic caves being this history book yeah and they haven't been to much yet but for the last year or two i've been trying to get up there more and do some work into it and so caves are a phenomenal resource for a geologist to get long records going back in the past especially from places like the arctic where you've had ice ages come and go and every time age comes and goes the glacier scraped away in any evidence that's on the surface and we are racing on the evidence of what happened but caves are this rare place where it's just tucked down there yeah so you can go down there and get some potentially kind of continuous pretty formations you've seen a case yes so the main way that these that he's got his work is that rain falls over a cave and that water seeps down through the ground drips and then bit by bit you know deposits more and more mineral crystals that grow up into these to lag mites and so basically the the idea here is that the chemistry of the rainwater gets incorporated into the chemistry of the mineral ok that's to lag my so we essentially have this record of the chemistry of how rainfall was changing about the cave as a slime i was growing through time and we can link that back to change isn't in climate in temperature in rainfall it's a different case so presumably this rainfall that seeps in to the ground in this way this carries the signature of chemicals in the atmosphere at the time is that the idea that's the idea and in particular what it tells you about as we look at the isotopes in even further than i but there's a lot of questions over how much warming can you have before you push that too far how fast might that happen it's not a simple thing to figure out so we look to the past to try to figure out what when did the  right and what was the climate like at the time how big of a push did it take to get all of that to thaw so you could read a lot by looking at this kind of information and then various caves tell different stories in different regions  a little dental drill actually and you drill out a little bit of sample here and there were you're interested and begin analyzing the chemistry to date it to figure out its age to look at all of it you know that's that's that's really quite interesting is how remote they of these caves that we have samples from are incredibly remote oh a way out in nowhere land i mean the kind of thing where you're flying into fairbanks then catching a smaller plane i threw a little in place and maybe a helicopter from there  what do you find with those so they do with that work is that whenever you have a glacier flowing around whether it's in new england or the last ice age or in some mountain in colorado it's scraping up the land it's moving you know mud and sand and boulders right and when it melts out it just drops those boulders so what we can do is we can go to a boulder today that we say oh that was dropped by a glacier when that happened we could date when that happened by knocking off a chunk of the rock and we measure the chemistry of the rock and we can use that to basically figure out the age of when the ice dumped that boulder on a landscape i see and so that's something that i that people sort of do all over the world glaciers and so the way this works yeah is it's actually pretty simple it's so there's cosmic radiation yeah i mean from deep space all the time hitting you be the table constantly and also getting bolder surfaces so there's something that happens when it getting cooked by cosmic rays the more brewing in ten builds up and so we go and we knock a sample off we bring it back to the lab and we know how fast the stuff is produced so if we measure how much there is with office to produce we can figure out how long that boulder has been sitting there so that's the origin many times to this because they get carried such distances and stuff but above all the age and it gives you this climate information as well you've looked at other kinds of information as well and you looked at like ice those kind of cores and i i think that you had something interesting to say about this because much has been made of the antarctic ice cores and in some cases maybe information has been distorted not not by the scientists but by climate deniers and stuff can you give us a little background on that what put those course tell you and how it could get mixed up so the amazing thing about these ice measure basically what the temperature was doing three times that snow was falling so when the mission with with the with the temperature was doing back through time in an arctic and you can measure the amount of c o two in little air bubbles that are trapped in those ice cores back through time  get a record of temperature going up and down over ice ages and this record goes back almost a million years from ice cores amazing so you get a record of temperature over the last million years you get a record of c o two for the last million years in the atmosphere and the amazing thing about it but there it is right in front of so so you look at that and you start wondering there obviously temperature and carbon dioxide are connected throughout the ice ages but how exactly are they connected and so i guess a point that's that you're alluding to here is you know a lot of people look at that and say oh my god look clearly c o two is driving temperature up and down just like today well it turns out if you look really closely at that record at any given event there's some uncertainties and some error bars but you could make an argument that maybe maybe this year the temperature is warming up just a little bit before the c o two starts right and so a lot of folks have said oh there you go look at everybody's getting it backwards yeah that you know c o two causes warming it's that warming causes c o two in the past and maybe it's doing the same today and maybe this whole c o two thing is bogus so they spent a lot of time atmosphere everywhere and that's because c o two is basically the same everywhere and we emit some c o two or comes from a volcano give it a few years the winds mix it is the same everywhere so it's a global record but this record of temperature from an arctic is like a record of temperature from anywhere it's about temperature there yeah yeah yeah so you know it's you got to be careful to try to take the record of temperature from one of the ways this is about global climate change sure when we're thinking about greenhouse gases and their effect on the climate you know the relevant thing to think about is well what is it doing to the global climate that's really the meaningful metric to use right so i spent a good chunk of my dissertation looking at all sorts of other temperature records we have from around the world because we don't have just records of temperature are from ice cores in greenland or from ocean cores all around the world or from lake sediment cores or all sorts of different techniques people use and we pulled all of these records together from all over the world slap them into a global average marine corps the ice cores the caves and all of this stuff it's also a great deal of data oh yeah in the geologic record all the information that's been amassed yeah it's a huge amount of what are you doing to me that must be incredibly difficult to put together and share out a big big global data sets of information yes is it is that must be a project in itself is what i say it's projects upon projects but there is a lot of data out there in the world and that's i think that's a key piece with climate science in general for today or for a million years ago it's a big complicated global climate system you know only way you're ever going to make sense of any of it is to pull a thousand or a million data points from the whole world all together so you can see the big picture yes i think that's when the challenging things with climate change is it's always we're always so inclined to look at one little spot or one moment in time but i need all that data on the table and you need judge amounts of data probably to make the models is that the case i mean are your models better as a result of having this huge amount of data absolutely absolutely so you need data always to test models right right we use our best physics and understanding of how the climate works put that into a question form and try to model it pertain to the result and say is that good is it not good who knows well take your model try to simulate a past ice age try to simulate some other climate of the sea can we actually get this model to reproduce what we see in the ice cores in the ocean cores all those different features so it's a key it's a key test if computer models can can you know capture a big climate change accurately that's it's quite amazing two things first of all that climate is so complex so dynamic would like to ask you about just trying to work through anything so complex and the the number of ways you need to approach the problem to fully understand i was there and so i think what you really have out there is what you should have you have a whole kind of spectrum of different scientists those who focus you know on the incredible details of a particular technique to the modelers to sort of generalists in between who can translate among the different groups so you do have to tread and do it you know i think actually the science i think i think pillar climate science has actually shifted know the first days of getting ice cores then you need a whole community people to disfigure out how the heck do you get into that what do you do with that is the thing true but i think at this point there's a lot more integration going on and i go to a lot of conferences and meetings and workshops where you have ice core people and ocean people and computer people and modern climate people and all sorts of cross pollination yeah trying to put it together they do make an effort to put it together the other thing another thing here you train students now  are you training them in this more comprehensive more holistic approach they are by having to learn everything they have to learn a bit of everything i would say yeah a little i mean it's always kind of a careful dance between not spread yourself too thin and i think for different people they're going to want to take different paths along that you know along the spectrum exactly but sure students who work with me i'm really sort of like that general perspective and trying to pull different different threads together so i think that comes through in my work with with them but but you always want to make sure something i'm really in fact about is making sure i'm always collaborating with the specialists who know the ins analysis and every last detail of a particular technique or  indicator or blab measurement or whatever it is make sure it's all kind of being brought right or just out of curiosity the technology i guess that's what you call the tools that you are able to use today seem to have developed a lot is that true very good as opposed to i don't know even thirty forty years ago i have no idea absolutely absolutely all sorts of measurements that we can make today that never were possible to get and he was gone  and they had all these so i might from back then but they were able to do that much in terms of analyzing it because they just didn't have the technology you know and the uncertainties weren't small enough to be able to make the measurements you would need to make and so anyway in the last couple years i've made friends with them into the hey can i take a stab at those they said of course this is right for the new technology and so now we're measuring things that they had first you know take a stab at forty years ago but where is it was a sample that they would get an error bar like this or they could even measure we're now you know out here the technology has gotten so good that it leaves no doubt at this point about the human factor here contributing to the present situation because you have such such good right now more no more questions isn't it interesting that for decades you could keep up this doubt business much of it deliberately generated but i mean that there in some circles there were legitimate scientists who had questions about it they don't anymore there is one more thing i've been asked about one of the favorite excuses for the deniers was about the earth's regular tilting what is that called and what how does that figure in there so the earth's orbit around the sun isn't static it slowly changes through time the earth's axis sometimes tilts a little more a to credited with three really thinking deeply about them all of these different cycles seem to be responsible for triggering for tipping off ice ages to come and go and we talked before about so it was really import for the ice ages and it seems like c o two is really important for bringing sure these orbital cycles seem to have been important for causing gigantic ice ages to come and go so maybe the warming of the last hundred years is due to these orbital cycles there's a lot of flaws in that logic but the simple list you know most obvious thing to point to is that these cycles are incredibly slow over twenty thousand years forty thousand years one hundred thousand year since the industrial  a course or do you like putting it all together what do you like the best model and i don't actually have a favorite area i find that i like a little bit of all of it as a scientist i find that it's easy to you know do you do the same thing day after day after day after day and i start to find it after a week or a month we're using ice cores we're using old layers of snow falls old layers of mud old tree rings all of these indirect ways to try to get some land some perspective on the snapshot of climb in the past yeah and they've all got advantages but they all have different far back something can go like the tree rings but i think our limited i don't know about the marine set of that course and stuff is one one of those can it be a a longer you know what i mean for sure for sure each one gives you different a different sort of again advantage so trees are great if you want to study the last few hundred years i mean you're not going to find that many trees that are one hundred thousand years old ocean sediments you know it's been my piling up on the sea floor for millions hundreds of millions of years so that's great for that if you want to go even further back in time in our history you want to go back a billion years ago three billion years ago and i got to go look to old rocks and so everything you look at gives you a different a different lens as you know further back in time or maybe you know higher resolution with more data points in time depending on the question you're asking nicely but there's usually a toward for whatever the question is your ass and you just got to find the right tool to that's going to give you the information yeah how did you ever get to do this in the first place did you just you know as a small child say i know i'm going to be a closet scientists when i grew up i don't know if i was going to be a climate scientist i kind of always maybe thought i'd kind of like the meteorologist thing the weather and thin together so it's gigantic which makes it fun but also you know that because it seems as though this might require a certain type in much of academe generally people tend as we said to be quite narrow but you stay in something forever you don't have to keep studying but in your field it seems as though you're learning something every ten minutes and you need to stay abreast of all this new information is that true and do you think it takes up yeah i think that i think that is true there is always more information coming out there's always new things and so you always pretty much need to keep up to speed on that because  know if you haven't kept up with the latest research for the last five years or ten years then you sit down for four months and get to it because it's going to be if you're going well you know you've got it you've got to have it so you know where we're at what the right question is to ask now you're always getting deeper into these questions right so i think you definitely need that right yeah and one more thing in terms of climate what's your prediction for the future in terms of the globe what can we take how far how much worse is it going to get and so the biggest control on how much more warming and overall change to the climate we see comes down to how much more carbon we emit primarily that's this the single biggest things c o two is the biggest not cranking up  thermostat how much more do we raise it a little bit more and sort of lead ourselves off fossil fuels in the next twenty thirty forty years or that it can't be done which maybe can be done yeah or is this sort of pedal to the metal forget about it boom we're going through this century and beyond with fossil fuels and if we do that well then c o two is going to up here and what i can tell you for sure is if you go back in earth history the last time c o two was up here it was an unrecognizable world i don't completely different completely different people always say well  higher in the past which is true and it was a completely different world in the past what it was overhauled is at the time what was alive is a very different terms of you know biology but you know if you're a c o two three four five times higher than where we started you're going to get rid of most of the ice on the planet which means sea level is going to go up a couple hundred feet so redraw your maps of coastlines around the world because that's going to that that's going to come in that'll take time to fully unfold but  if you look at the evolution of the sort of the scientific predictions i think we have on the whole tended to have too much of a sort of a linear perspective on the earth system and kind of thought it's a little more stable and it moves very you know simply and linearly and i don't think that's quite the way it maybe actually works and i think when we look at a lot of our history we see that that's true we can do all sorts of you know why old jumpy thing yes yeah right so that no matter what happens if we could switch to renewable and do all the right things tomorrow we would still have this warming continuing for significant warming now that we can't reverse it is that the idea we have a few more decades and if you know there's more warming locked in while ice takes a long time to melt and so we have huge ice sheets in antarctica huge issues in greenland to create the temperature up a degree or two or three you're going to melt back a lot of those ice sheets but i sheets are two miles thick you can't melt that in two days or two years or twenty years so a lot i say going to melting for centuries to millennia which mean sea level is just going to be going higher and higher and higher and i think that will be the longest lasting legacy of what we're doing today is  unless we figure something out i mean sea levels are going to be rising for the next it sounds wild but it's just basic physics you're going to rising for the next thousand plus years which is pretty challenging exactly especially when you look at burgeoning population around the world this is going to be a lot of difficulties but maybe they will come up with some way to to pull this carbon out of the atmosphere you will go what are the sort of the thresholds the tipping points the you know what what's what's on the horizon cutting into that and yeah are you in the field this summer or anything and what are you looking into not too much the summer little bit of a period this summer last summer i was in quite a bit next i'll be back more but i guess for field work these days it's largely that project in the arctic going caving so if they get back up there to do some more of that and let's see another project now that i'm just beginning to look actually at we're talking about melting ice sheets collapsing raising sea level yeah so i'm starting a project now to do that actually right here in our backyard in new england where we have big mountains that were poking up into the ice sheet as it out that way during the end of the last ice age and so i'm climbing up and down along the east coast like this great well the very best in your career it's wonderful to hear this very comprehensive approach to things and  hope you'll be talked into writing a book for the public to try worrying about it should do i don't see this is going to be a need actually that the scientists have to try to do this to make this