Skip to main content

tv   Johns Hopkins Climate Change Symposium  CSPAN  May 3, 2019 9:01am-10:06am EDT

9:01 am
[inaudible conversations] >> good morning, everyone. good morning and welcome to the national academy of sciences. welcome to today's symposium, changing by degrees. multidisciplinary approaches to climate change. i would like to welcome you all and thank all of our panelists today for their participation in this important symposium. i would also like to extend a warm thank you to our keynote speakers today. we have kirk johnson from the director of the national museum of natural history. i just checked his title with
9:02 am
him. and governor martin o'malley the 61st governor of the state of maryland. on behalf of the johns hopkins university we would also like to thank the national academy of sciences for their support and for graciously hosting this symposium. today's event is an important one, a culmination of over a year's worth of planning at the arts and sciences advanced academic program. a variety of interests from museum studies, cultural heritage and digital cureration and our faculty comes from the environmental policy program and energy and policy and climate change, they all work together over this past year to bring experts, leaders, academics and elected officials from a variety of perspective to participate in this multidisciplinary symposium. the diversity of thought here
9:03 am
and the fields represented here uniquely situates all of us to explore different elements of climate change and different approaches to climate change. our goal really today is to capitalize on this multidisciplinary approach. we would like to provide an opportunity for dialog and solutions for complex progress at that will allow us to progress as a global society. finally, this meeting is an opportunity for our current students and also our alumni to showcase their work on climate change. many of you might have seen some poster presentations out in the auditorium. you'll be able to view their work during coffee and lunch breaks. our next speaker is mary fox. mary is the co-director of the risk sciences and public policy institute at the johns hopkins university of bloomberg school of public health. mary will provide the keynote presentation. so thank you, please relax,
9:04 am
enjoy, bring your great thoughts with you today and i look forward to participating with you. thank you. [applaus [applause] >> thank you very much, first thing i'll not be giving the keyno keynote, i'll be introducing keynote speaker. thank you, dean donahue. it's been great working with you. my part in climate change has been studying climate change adaptation, including some strategic planning with our national program at the c.d.c., climate and health program which was launched in 2009. their big contribution to
9:05 am
adaptation is called brace. it's an adaptation and risk management frame work, building resilience against climate effects and this has been launched and used in 16 states and two cities. so in the ten years that this program has been around, we've made some progress, but certainly much more to be done. and of course, ten years is not a long time in the grand scheme of things and i think dr. johnson will be talking a little bit more about the grander scheme of time and the climate challenges that we face. so since 2012, dr. kirk johnson has been the director of the national director of museum of history. prior to joining the smithsonian, he was at the denver museum of nature and
9:06 am
science. he earned scientology and paleotology and academic preparation leading up to his current work and he is very dedicated to his education mission. i think we are going to see a little of that today. a preview of one of his television programs and he also has many great books that my kids have enjoyed. i know i will be learning a lot today and i think we're off to a great start. so, let's welcome dr. johnson. [applaus [applause] >> good morning, everyone. so, climate is a pretty big topic and i'm going to blow the boundaries on the temporal
9:07 am
scale and the scale, the deep time, which is our planet's history and polar because at the end of the day climate is a very cold to very warm story and i want to give the parameters to that. we live on a planet with polar ice. you go to the arctic or anti-arctic there's polar ice and most people haven't seen it, it's an experience to go to greenland, alaska, seeing ice sheets up to 10,000 feet thick and i had that privilege 37 years ago when i was just finishing college in alaska. and this is a picture i took in 1982 of sea ice melting off in the spring in the northern bering sea. and it's the kind of thing i never thought about before i went there that there is such a thing as sea ice and polar ice caps. if you look at a view of the arctic in the winter of 1980
9:08 am
you see sort of three flavors of ice. you see the ice that forms during the winter, which is this color, all the way down to the bering sea. you see the ice that persists from year it year floating on the arctic ocean and this is five or six feet thick and you see the ice in greenland and those are ice caps 10,000 feet thick. so this ice is a year old. this ice is a few tens of years old and this ice is 120,000 years old. when we talk about the ice caps, it's confusing because there are several different caps of ice, some are young, some are efemoral and some don't survive the summer and others survive the summer and build up over time. if you go to the same exact spot it looks like this, in 1980 it looked like that. the annual ice melted back and at the end of the melting period that's what it looks like. which means that this kind of
9:09 am
ice can survive the summer. so that's the way it had been for a long time and i'll come back to that, but that's changing quite rapidly now in ways you can see quite dramatically. so another way to think about ice is how long has ice been around? it turns out that the story of ice brushes very closely with the story of human civilization. here we are today. if you were looking at the same globe simply 20,000 years ago you'd see that most of north america and northern eurasia is covered in ice sheets thousands of feet thick, which means for thousands of years, ice survived summer in north america and asia and persisted to form ice sheets. it's sort after little known fact, if you look at the map of north america, for instance, today, and scrutinize it, just look at that map and just ponder what you're seeing. you see greenland with the great ice cap and alaska with
9:10 am
its mountains. hudson bay is a hole in the middle of canada. around hudson bay you see big lakes be like the great lakes, our great lakes, but also the great lakes of canada, stretching in the arctic. i had a map of north america on my wall in my office and looked at the map. what i was seeing was the footprint of the ice age because many times in the past and most recently just 18,000 years ago, there was an ice sheet covering north america that sat on top of that footprint. so, that ice covered boston. boston was under ice. that ice covered new york, that ice covered chicago, the ice covered seattle. to great depth. it wasn't an annual ice, it was thick, glacial ice cap ice. you can imagine with that much ice on land, where did that water come from? it came from the ocean, as a result the oceans were several hundred feet lower in terms of sea level. very different world, but it's
9:11 am
only 18,000 years ago. that's only four times the pyramids back, twice the age of the hume civilization, from geologic points of view it's not that long ago. i grew up in seattle, which has the space needle. built for the world's fair. 605 feet tall and you'll see later, i got the pleasure of climbing to the tip of the needle, which is a great experience. but 18,000 years ago there was 3,000 feet of ice where seattle is today. so think about this. using the space needle for a scale, that was seattle 18,000 years ago. right? that's a mind-blowing thing. whenever you go to seattle now, every bit of seattle is post-glacial topography, recent post-glacial topography. and seattle people don't know that, after the nova show they will. they live in a post-glacial,
9:12 am
shaped by 3,000 foot ice caps that were there quite recently. what's remarkable even more the ice came and went several times, maybe as many as 20 times. we are live in a dynamic planet where climate has naturally changed in tremendous ways recently. so, in what we call ice earth, our earth. the world we live in today, there are polar ice sheets. there's two flavors on earth. cool periods like the one where we live in, ice is at high latitudes. there are cold periods where the ice came down to mid latitudes and went down forth, glacial, interglacial, glacial, interglacial. we didn't realize that until the 1950's.
9:13 am
and by the time we start drilling the sea floor and realize 25 or so times that the ice came and went during the last two and a half million years. so we are ice people. in fact, if you think about it, humans evolved during a climate that was cool, cold, cool, cold. once we learned how to interrogate the ice caps, things got even more interesting because an icecap, if you think about it 10,000 feet thick on greenland, antarctica, is a stack of snow that fell in the winter and survived the next summer and piled up. so it's a case of snow surviving the summer, thickening up and as a result the top of greenland and antarctica builds up over time and thickness. greenland is in an area that
9:14 am
gets much more precipitation than antarctica. so in greenland you have about 120,000 years of accumulated ice. in antarctica, you have 800,000 years of accumulated ice about the same thickness, one is accruing much more rapidly and that's greenland. if you drill a hole in the ice and it has layers and you can interrogate the layers, and look at the atmospheric gases and the isotopes in the layers. you get a record of both climate temperature and the composition of the atmospheric gases. and this started recently, the first big core in 1966 at a place called camp century in the northern part of the greenland. they drilled through 4,000, 5,000 feet of ice. and they received 120,000 year
9:15 am
record, the history of green lar land. and greenland didn't have ice when you looked at the bottom of the pile. and what did greenland look without ice and why didn't they have ice? an interesting question. in antarctica, ten times the size of greenland, the south pole fully covered in ice. and you can see the isotopes effects there in the middle of the domain, well over two miles thick in the middle of antarctica. that's a lot of ice. if that ice melts the sea level changes by hundreds of feet. dome sea down in the lower part was the site of an amazing core that was drilled in 2004, or published before that, where the record is a remarkable climate record. so, what you see on the bottom is age in hundreds of thousands of years.
9:16 am
so 800,000 years on the far left. now on the far right. you want to put yourself in context, humans evolved here, homosapiens first appeared here and we got our civilization there. so we have evolved and become civilized and urbanized in a world that has glacial ice oscillating. it oscillatines in an interestig way. it's a seasonal basis, winter and summer. this ice teams to be changing on a metro gnome about 100,000 years. you look at the temperature, cold warm, cold warm, cold warm, cold warm, cold warm, cold warm, cold warm. every 800,000 years that's happened about eight times. about 100,000 years you're seeing this transition from a glacial, glacial. and what's driving that is our
9:17 am
solar system. the tug of the big gas planet is warping the earth's orbit around the sun and having periods where it's cooler, where show can survive the summers and piles up. and periods when it's warmer where snow does not survive the summers and it warms up. so, we have a seasonal thing happening and we have a thing that's being driven by the gravity of our solar system happening. what's also remarkable about this curve is all of this data come out of the ice core and you can see that methane and carbon dioxide, both greenhouse gases when they're elevated, it's warm. and when they're not elevated it's cool. you can see the relationship between greenhouse gases and temperature in a pre-human world. that's how the planet works. what's so amazing about the study of our planet is, we are learning stuff so fast right now, that most of the things i've told you were discovered after i was born. and we are learning stuff at an increasing rate so science is
9:18 am
awesome. and we're learning more all the time. and you see a pattern like this, and wow, there is so much information in this pattern. note this, i actually want to point out a critical feature here. the concentration of carbon dioxide in the atmosphere, parts per million goes in a cool period from around 180 parts per million to a warm about 280. so for the last 800,000 years, the concentration of carbon dioxide gas in our atmosphere range from 180 to 280, back to 180, back to 280. very narrow parameters, right? it's a pretty tight system. when it was 180, seattle was under 3,000 feet of ice. when it was 280, the ice was back up in greenland. right? so you're seeing effectively seattle being buried each time you bottom out the co 2,
9:19 am
seattle being exposed and of course, at this point here, right now, that's the time we live in. that's our world, we're in warm world, no ice caps on boston, seattle, chicago. so let's just say for the last 800,000 years all it takes is 100 parts per million co 2 to dramatically change the world. that's pretty interesting observation. great data from a core in the mid antarctica. and then there's this remarkable curve. this curve is called the keel chi -- keeley curve. and it was started by charles keeley. he started up an observation post in hawaii and measured concentration of carbon dioxide in the atmosphere and started in 1957 and kept at it for 50 years until he died, and then his son took over, and the scrips co 2 project, go to
9:20 am
their website, amazing data base shows one man's data set of what's happening with carbon dioxide in the atmosphere. you'll note a couple of interesting points. 310 is where he started. remember, i said 280 is where the ice core left off. already it was 30 parts per million higher than during the normal typical highs we've seen for the last 800,000 years and you can see a second thing, which is a little zig here, that's winter summer, winter summer going up. that's why it's regular, winter summer, winter summer. look at the trend of the curve. what's most remarkable. this is data from two days ago, may 1st, 2019 from scripps. two days ago co 2, 214 parts per million. started down here at 314. so in those 59 years, call it. we've seen an increase of 100
9:21 am
parts per million, and i showed you what 100 parts per million did, it can put an ice sheet on seattle. now, for me, this says several important things, one was i was born right there. and i'm standing in front of you, and i'm not that old. we're operating planet on a human time scale. that's a remarkable thing. i was talking to you about hundreds of thousands of years and tens of thousands of years now i'm talking my life span. that's an important fact to realize is that time is a very fungible thing. we have things happen over the millions of time scales, but if they're happening on your own personal time scale or the time scale it takes you to go to college or pay off a mortgage, this is real. the second point is really interesting about that is that we haven't been here as humans ever before. humans have never experienced
9:22 am
over the long history of our species, last 300 years, we've never been more than 300 except for us. our generation is a 300 plus ppm people. we're unique, different from all people that preceded us because we live in a world that's seeing increased co 2, which means increased warming. but what it fundamentally means is that we are the generation of human beings that are geology. we're operating not only in a time scale that's fast we're operating in a scale that is geologic, it's global, right? we've actually changed the atmosphere in a way that the planet changes the atmosphere. we're not a flea on the elephant. we're an elephant on the elephant. it would be cool if it were geology because we're great at
9:23 am
sourcing carbon on putting it in the atmosphere. we're not so great pulling it out of the atmosphere. if we figure that out, we wouldn't be facing the challenges we're facing now. we're 50% geology, the other 50% we're not geology and that's sort of the basis of the problem. so, here was september 1980, summer just two years before i got there. 32 years later, 2012 summer, the summer looked like this. right? so what you're seeing here is that multi-year pack ice is melted back. that is stuff that doesn't come and go, it literally melts away. and it's created the northwestern passage and the northeastern passage. and shifting across the arctic where there wasn't in 1980. that means the arctic is presently militarizing. you think of anti-arctic in 1957, the treaty, nations of
9:24 am
the world said we better call antarctica off limits and call it the people's continent. we never made that deal with the arctic, eight arctic nations and right now, russia and the united states are having to militarize and think about shipping activities, i mean, because making the most ice breakers is not the arctic nations, it's china with korea close. you can get from the ports in asia to the ports in europe 50 days faster if you go over the top than if you go around to the panama canal. so what you're seeing in front of your eyes in your own human time span is we're getting a new ocean. for the last 800,000 years and more, the arctic ocean was impassable because of sea ice, but literally now, literally in the last 30 years we've got a new ocean and all of the geopolitics and all of the biology that comes with having
9:25 am
a new ocean. it's a pretty amazing thing. but i didn't come to talk about ice. i came to talk about trees. and why trees, you say? i mean, trees are just trees, right? they're just things that grow in the ground and we know the basic rule of a tree. the tree makes itself out of carbon dioxide grass. you pull a tree out of the ground and shake off the tree roots, the vast bulk of the tree is made of carbon dioxide gas, the roots, and through the leaves and photo synthesis, and it's made of gas. that didn't feel like it when you're hit by a bat. trees are interesting things, they grow by adding rings. so here is my 81-year-old father and there is an 81-year-old tree. right? so we tend to think of trees as
9:26 am
cannot like us, but in fact the average tree has the average life span of a human. they're bigger and don't move around as much, but they are also part of the carbon cycle like we're part of the carbon cycle and turns out in the worlds that i'm going to tell you about, in the worlds that don't have ice, trees are very important. imagine a world that doesn't have ice. that was this planet as you'll see. we call those hot-housers. there's no polar ice caps at all. and like the ice housers who have a cold and a cool phase, hot housers have a warm and a hot phase. i want to introduce you to these things. you haven't seen these. the last time there was a hot house on earth was 34 million years ago. most of you are not paleobotanists. i'm going to show you this.
9:27 am
what you need is a paleobotanist. we use extremely technical equipment-- we use a shovel. i extract amazing evidence of earth's past. you can crack open fossil rocks and find leaves of trees. every year it's making 300,000 potential fossils that are really great and when you find those things, you can start to build evidence of what the place looked like when those things fell off of trees. so when i go to a cold scene in wyoming. might say that's a cold scene in wyoming, no, that's a fossil swamp. i can rebuild the ancient landscape and put a forest back
9:28 am
on top of that landscape in a heartbeat. i do it without thinking when i go down the road. this place is a swamp, there's a lake bed, a tropical rain forest. that's the waning.y i think. and my friend calls it time travelling with a shovel. it's genuine time travel. i can go back to ancient worlds and rebuild it with a shovel. i can't go forward in time. working on that. fossil leaves are incredibly beautiful. you can see the veins clearly. the veins on a leaf are how the planet moves water from its roots to the chloroplasts to the pores. it's an irrigation game to the engine that is making carbon gases. the pattern of veins varies from leaf to leaf, kind of like
9:29 am
a fingerprint on the criminal, if you show me the leaf, i can tell you what the plant is. every tree is dropping hundreds of thousands of bar codes every year, but what's even more amazing is that these leaves are like fossil weather stations. the size of the leaves has a relationship to the amount of rainfall. the nature of the margins has a relationship to the mean annual temperature. the spacing of the small pour pores on the leaves tells you the concentration of carbon dioxide gas is. and the bite marks of the insects tells you about the ecology. you can tell a lot about climate from the leaves the same way you can tell about the climate from ice cores. it's a crazy complicated world and we had to do this book called the manual of leaf architecture. there are literally living today, 300,000 different species of plants. they all have different kinds of leafs.
9:30 am
how do you pars that and realize the living ones are descendents of the millions of others that died over the last several hundred million years. now, think of that forest. today forests are not evenly distributed on our planet. there are places that have ice caps. there are places that have arctic tundra. there are places that have deserts. and there are different kinds of forests. there are tropical rain forests. there's the boreal forest entirely of spruce trees and there are forests like the ones you're used to decidous hardwood forests like here and there and there. today there are 3 billion-- sorry, 3 trillion trees on planet earth. less than it used to be during a greenhouse earth because we're in a time of ice, and a time of trees. in a time of trees, this map would have been much more consistently green. you're looking at the tree map of a cold world. it's not ideal for trees.
9:31 am
just trees there are about 60,000 living species of trees. we've got a look to work with her. what's cool is many of the species have lineages that go back 60 million years and we can interrogate trees not just thousands of years, but millions of years and tens of millions of years. so i'm going to do an experiment with you now. and show you a bunch of leaves and tell you whether they're forests. i know you're botanists. >> here is a maple leaf, an oak leaf, a boxwood leaf, there's a hazelnut leaf, there's a cottonwood leaf, there's a conifer branch with cones and there's a large raspberry leaf. where do you think that is? here, right? no, it's in china, actually. which is a really weird thing. it turns out that the forests
9:32 am
of new england and the forests of northeastern asia and europe are similar. that's a very weird pattern. it is the forest here, but the pictures i showed you i took there on the river in china. this is one of the great botanical mysteries in the 1780's when people botanists from sweden went to explore the flora, went to china and found the flora that they left behind in sweden. it left a pain in the brain. eventually pain in the brain because it didn't make sense. how do you get widely separated and separated in asia, separated by the atlantic ocean, how to you do that and break the world forests into three distinct disjunct populations? that problem really puzzled me. there was interesting data. i am a geg to-- i'm going to show you a couple
9:33 am
of trees. this is the japanese tree that grows in japan and china, beautiful leaves. here is a fossil of one of the leaves that i collected in washington state. so today, the tree only grows in china and japan. i found its fossils in washington state. pain in the brain continues. and other trees, decidous c conif conifer, you want to see a beautiful one, 12th and constitution. a beautiful tree this is a decidous tree. evergreens and conifers. and here is a beautiful fossil of this, again from washington state. the hypothesis is in a warm world, pre-ice world those three forests were once connected across the top of the globe. that's a testable hiypothesis. you can go to what was the top
9:34 am
of the world and test the hypothesis and that's precisely what i started doing in 1984. i went to the most northerly place you could go to and here is the north pole, and tip of greenland and the tip of here is latitude 82 north. more than a thousand miles north of the nearest living tree you're up in the arctic tundra. polar darkness there, and it's a cold place. when you go there, it's an ice house world. right up in the ice sheets. this is a very complicated image, but if you'll note there, that's a 300 foot high waterfall. you're looking at the edge of an ice sheet that sits on top of a land mass. this is not greenedland. this is on the top of the island and there's a much
9:35 am
younger me standing at the foot of the ice sheet. i wasn't there to look at the ice. i was there to look at the evidence of the ancient greenhouse world and see if i could connect those three forests. and it turns out to be surprisingly easy to do. we, as we flew around the arctic, incredibly remote, difficult access terrain. no plants at all, the surface, except for a few grasses. one woody plant called the arctic willow which is about this tall literally not even a shrub, and really inhospitable place. the perma frost goes down 3,000 feet. this place is cold. but as you fly around you see great stripes of black rock which you know to be coal. you know coal to be made of fossil ice swamps. and you look at the coal seams and grcrumbly bolder things tur out to be a tree.
9:36 am
that's a meter and a half diameter tree in a blizzard in july in the high arctic and we're just stunned to find these things. it's as though we were walking in the puget sound lowlands, but we're thousands of miles further north and 50 million years earlier. you could see the modern tree line as this line here. the nearest trees are literally thousands of miles away. and these trees are all over the place in the high arctic. and you get entire standing forests of the tree trunks. as you dig into the ground beneath the tree trunks you find logs and fossil plants and you've seen this before. and this is the redwood, which grows in china, but i found it in washington and here it is in the northern arctic. that was a hypothesis that was easily tested and robust. there was in a warm world a continuous forest across the top of the world.
9:37 am
the japanese tree, you've seen that one before. this one you might not recognize, unless you go to the kuwait aquatic gardens, it's a lotus leaf. here is your arctic 50 million years ago, no ice to be seen. mean annual temperature probably 55 degrees centigrade. not the global average now. what we learned from this exercise was when the world warms, a warms asymmetrically. the arctic warms faster than the equator. the equator warms, for sure a problem, but the polar regions warm extremely more. so, it was an amazing thing and what kind of animals we find. we found fossil skull. this is a fossil securely from latitude 82 of a flying lemur.
9:38 am
and this is a fossil turtle. the jaw bone of a small alligator. and these are animals we're finding at latitude 84. this is the arctic of a whose house world, with lotus, and animals, and this is what we built for the museum of natural history showing the arctic as it was 50 million years ago. the story doesn't stop there. in early 2000's there was an american expedition to the center of the arctic ocean, two ice breakers and a ship and drilled down into the top of what's called the ridge to extract fossil to understand the history of the arctic ocean basin. about an 8,000 foot ocean basin. at the bottom catching plants and animals, and what they found much to their amazement was not fossil marine plankton, but the spores of a floating
9:39 am
aquatic fern that lives in fresh water in the subtropics today. it's called azola. it's the size of your fingernail. you can see it in new orleans or the amazon. it is in fresh water and completely clogs water ways. here is a picture i took on a large make in amazonia. it's a rapidly growing plant and like mad in subtropical and tropical waterways and that's what they found at the core, at the bottom of the arctic ocean in rocks that were 47 million years old. the arctic ocean at that time was not only not frozen, it was warm, and there was so much fresh water runoff there was a lens of fresh water on top of the salt water ocean floor of the arctic ocean. that's a different arctic. that's a hot house earth. now, i want to talk about
9:40 am
palms. palm trees are kind of a classic indicator of warm, in fact subtropical climates and there are about 2000 different palm trees in the world today and they have a very tight distribution. they range within about 30 degrees of the equator and see quite a broad distribution, very common in the tropical rain forests of the world and warm dry areas and date palms and things like that in the desert. palm trees can be wet or dry, but they have to be warm. if you freeze them at all. they are toast. if you imagine, in a warmed world where you have forests up there. in theory, the palms would go further north, too. that's a question i asked. how about a warm loving plant where does it go. you can go to wyoming and find beautiful palm fronds as fossils. and this is a place near
9:41 am
bellingham, washington, washington state. and making of north america, a nova special aired in 2015. we were up in southern alaska filming a beach where i knew there were fossil leaves, but i was expecting leaves-- and much to my amazement and good luck it happened on camera, we pried up a palm frond up from a beach in alaska, it's seven feet wide and it has tropical rain forest leaves next to it, nearest town is sitka alaska. wow, how far do palms go? i went to the valley, latitude 61, and here is an outcrop of geologic strata the same age. and we're using an alaska climbing stick, and it's a way to climb up if you don't have a ladder. and we're looking at the
9:42 am
outcrop, because one of my buddies spotted from the road and spotted what was in fact a palm frond. those the northernmost. and in geology, that's the northernmost because that's the northern one you've found. so what we know is that the, in the hot house earth, the world was pretty warm at high latitudes. so if you're thinking about your own personal global warming strategy about where you're going to move to, michigan or something like that, or british columbia, you might want it adjust your dial a little bit. here is a location of palm forest that is we found along the coast of western north america. and there's alaska. so, if you want cognitive d diss
9:43 am
dissonance, say the world alaska and palm. let's turn to the arctic, it wasn't the southern hemisphere phenomenon, antarctica was forested. the ice in antarctica is a recent phenomena of ice house earth. and making this new-- show you the clip called polar extremes. we took the fastest trip to antarctica ever. we were there last month for 48 hours and went to king george island on the peninsula and met this guy, this is marcel, the head of the chilean anti-arctic survey and a paleo botanist, and you might ask why you need that, it's a place to find plants. and this was a beach and, there were penguins everywhere and fossil tree leaves like beach trees. so, today antarctica has two species of vascular plant, a grass and smaller, and the
9:44 am
entire continent. it's replete and rich with fossil trees. so we're showing clear evidence of a world with no ice and you would rightly ask, when did that happen? what's the story here? and it turns out if you look at the last 65 million years of our planet's history, you see a very interesting pattern and this is a pretty cool graph. it shows you basically zero is today's temperature, which is where we are today. and if you go back 50 million years, the temperature was about 12 or 13 degrees warmer than it is now. remember, we're all interested in keeping our temperature shot from going up two degrees sea. showing you what what's possible. one of the reasons is two is on the path to three, three is on the path to four and four is on the path to 12. so, there's no joy in saying we're going to keep it here and flipping over, it's like
9:45 am
driving a truck in the wall, five miles per hour or 100 miles per hour your choice, but i'd prefer five miles per hour and that's why i want to keep it two degrees sea. you'll notice during this period 65 million years to about 34, it was quite a bit warmer than it is today. 8 to 12, even in this period, there are abrupt spikes where it shoots way up. these little spikes are called hyperthermal, a time in an already warm world that already has palm fronds in the arctic area, the temperature jumps up several degrees rapidly. one of the things we learn from those spikes, note they're steep on the back side and they come back down. we're like what? okay, you put a lot of carbon in the atmosphere, what draws it down and how long does it take? these are some of the best examples understanding how the natural earth draws carbon dioxide out of the atmosphere, it does it by weathering of rocks, basically. and the good news, that looks at this curve.
9:46 am
the bad news it's not fast on human time scale. it takes about 100,000 years, this little spike about 100,000 spike. so it takes about 100,000 years to draw the carbon dioxide back down. make no mistake. co 2 we're coming down now is not coming down by natural processes, it's only coming down by humans on -- on the equation. 34 million years, we get our first ice, starts around 34. and much later, around 5 million. and between this no ice world and ice world is a boundary between the ice house-- or the greenhouse and the ice house. but what it also means is it's been 34 million years since any of the earth's eco systems have lived in a greenhouse. 34 million years is a long time. i'm not going to pretend it's not a long time.
9:47 am
many, many, many, many different iterations of species have come and gone in 34 million years. our world, our world, not just us, but our world has adapted to an ice house. so we go to an earth house-- a hot house, it's a planet where things are going to be quite different. so here is our choice. now, we're-- we presently appear to be leaving our ice house and headed toward the hot house. you might ask the question when is the last time that happened? because the previous iteration was leaving the hot house and coming from an ice house. when is the last time our planet went from ice house to hot house. that's a really interesting story. here is the last 500 million years of our planet. now we're really talking again, you know, deep time here. and you can see that the transition between ice house and hot house has only happened a few times. it's the last 34 million years, this is our time, and this is us, we're leaving this world,
9:48 am
and that previous hot house lasted the entire time the dinosaurs were here and saw the extinction of the dinosaurs and the first ten years of mammal evolution. here is the ice house before that. so the last time we went from a greenhouse, sorry, last time we went from an ice ice to a greenhouse was there, 250 million years ago. you can't say we're very practiced at doing this particular task. so that's the challenge for us as humans, as geology, creating our own climates. how do you actually deal with this transition, which is, frankly, relatively rare in earth's history? all right. which is where museums come into the mix. i work in a museum because i find museums to be powerful communications of science. that's why i do television. it's important for me to make the story of what's happening on planet earth understandable to as many people as possible. and just down the street from
9:49 am
us is the national museum of natural history, it's an amazing museum, it sees about five million visitors a year. what's really cool about it, most of those visitors are tourist froms united states and around the world. every year it's a different five million people and means in a decade we might see 50 million people in the building for social and formal science learning. do we do a good job. and when we opened this museum, and the smithsonian has been around since 1846, but the natural history museums buildings opened in 1910. when it opened they opened an exhibit about pre historic life and this exhibit came to be known the hall of extinct monsters. and that hall remained open with adjustments in next over hundred years until 2014. we ripped it out and building the last six and a half years, a new exhibit about history of life on earth, the history of climate on earth, the history
9:50 am
of people on earth and the thing that's going to be so cool about this new exhibit is that like -- unlike any other prehistoric exhibit, this one is not going to end in the past, it's going to end in the future. this exhibit that has dinosaurs in it, we also have people, we have agriculture atrade and civillation and the discussion of the future. how do we face the future together. here is the sketch of what it's going to look like, and the good news is that it's all coming together nicely. here is the tyrannosaurus rex and a complete skeleton of a tyrannosaurus rex. tie r tie-- tie rex was a denizon off the
9:51 am
hot house world and here is a de denizen off the ice house world, this mammoth. and here is another ice house dennison. it's a 50 foot shark that lived in washington d.c. 3 million years ago. an ice house animal. and one of the important ice house animals that we're going to see lots of in the exhibit and they're these things. and this thing, this young reptilian denizen of the hot house earth, a child born in 2019 will be 21 years old -- and will be 89 years old and we
9:52 am
know that all the stuff we are thinking about and concerned about, it will happen during this child's life. this hall is for that kid and all of his friends as they pick up the pieces from our part of being geology and take up their role of being geology. and the hall is very near being completed, actually opens on june 8th, only 38 days from now so i invite you to come to washington d.c., and if you have kids for sure bring them to the opening on june 8th. it's going to be an amazing thing and the premise of the hall is that the earth's distant past is connected to the present and future. and fossils of deeply relevant to the future because they give us up the full scope of what our planet can do and helps us understand what we don't want our planet to do. we have some really cool interactives in the exhibit like this ice core interactive which helps explain the ice core drilling and i was really
9:53 am
annoyed at the two small humans, ran into the humaexhibi full of dinosaurs, and were locked in on that screen instead of looking at dinosaurs, our 21st century children. and we've worked with climate in the hall. and deep time climate scientists around the world to build a plausibly curve for the planet. this goes back 500 million years. i don't know what happened there. go back. what it shows you is those periods of cold ice house, our ice house, it also shows you those spikes and really makes the point, here is humans, working in the ice house world and today's temperature. that world is a world without ice caps and as you zoom
9:54 am
forward you realize this next graph, here is 18,000 years, here is now, that's ice on top of seattle, here is the warming up to the 10,000 years ago, amazing stretch as humans. 10,000 years as effectively no climate change, 10,000 years of agriculture and cities and cars and buses and planes and everything we like. here is the beginning of the industrial revolution and you can see the tip of what's going to happen next. this is a key point. most of what we've experienced in the last century is humans being humans, not impacting the climate. the climate impacts are coming now, that's ahead of us and really, whether we go for a low co 2 future, sorry about that. shouldn't be going that way. low co 2 future or a high one determines whether or not we go across the line again, the line that has ice caps on earth or ice caps not on earth. many people think that ice caps
9:55 am
are doomed as we go back and the question is, how long does it take to do that? and we are worried about that how long it takes for the sea level to come up. these are important questions, but i hope you learned about ice house and hot house. what i want to do now is show you just a quick clip. we did a film that was to come out next february to tell the story that i told you using the medium of television: i want to give you a one minute clip of what that's going to look like. >> the arctic, and the ant antarctica, our world, vast, frozen, empty. yet, hidden in these rocks buried under the ocean, grafted in the ice are clues with a
9:56 am
totally different story. >> look at this. >> full of surprises. >> it's a whole forest! >> i'm kirk johnson and i want to take you on an adventure back in time. just walking around and carrying a mammoth tusk. >> and around the globe from one polar extreme to the other. to discover an earth vastly different. >> it just looks like mars. >> from the planet we know today. >> this place is so totally amazing. an arctic that was once a lush forest. antarctica, full of dinosaurs, in a time when ice sheets extended from pole to pole, turning earth into a giant snowball. what powerful forces drove the pole to such extremes? what does it mean for our planet's future? find out the true power of ice. >> this is amazing out here.
9:57 am
>> polar extremes, coming soon only on pbs ch. pbs. [applaus [applause] >> here is your assignment june 8th at national museum and february 5th on pbs. thank you very much for listening today. [applause] >> are there questions today? if there are questions, i'll take them. >> are any of your graphics going to be available? we're doing some presentations, i could really use a couple of those graphs. >> yeah, some of them are available and some not. so let me-- see me afterwards and see what we can do. some of them are part of the exhibit and part of the nova show as well. absolutely. >> okay.
9:58 am
yeah. >> the travel you're doing, we really need this. and i was interested in the one slide where you had the three, the co 2 and the methane and the temperatures. is it-- what act is it that triggers the ups and the downs? is it volcanic activity back then that did that or-- >> no, it is the oscillation of the earth in its orbit. this is the cycle which basically is pulling the earth into a slightly more favorable condition for building ice to a slightly less likely one. so, what you see on-- if you look back and interrogate the earth's climate history there are multiple causes for climate change that have natural drivers and we're doing a pretty good job of picking those apart, but that
9:59 am
regular back and forth during the 100,000 years, that's an orbital excentricity basically, that's a natural thing about the earth wobbling on its axis. that will, but it has-- it's been going on since the beginning of time. so it has different impacts depending where the actual concentration of co 2 is, it happens in warm world and a cold world. if it warm world it doesn't trigger ice formation. ...
10:00 am
you do know the general, tempter type at the relationship is still being hotly discussed which gets us back to how fast for the temperature to adjust. we know it takes a lot for the earth to come into equilibrium with the co2 in atmosphere. one of the places we went to the show was a place in virginia which was 3 million years old which had effectively the same co2 as we have today, but there were, shoreline was 80 miles inland from newport news.
10:01 am
he basically, as the future goes up, the ice melting is taking that. and how fast it takes four to come to equilibrium is to something that is really one of the most important questions. that's question but how fast it will rise. there are multiple ranges from as little as a meter by 2100, the several meters. that uncertainty is in the space of lots defense right now. >> a couple weeks ago the house for the appropriations committee had a hearing, and john kerry was invited. one of the issues that came up in a bit of back and forth was a statement that greenhouse gas concentrations in the atmosphere during the course of all of human existence have averaged a very, very high level, like 2000
10:02 am
ppm for something. i something. i don't know the exact number. i think the point they were making is that if you look backward over long time that the concentration of greenhouse gases have been very much higher than the art today and, therefore, not to worry. can you clear this up for us in terms of what that the pictures like? >> sure. i mean, there was a lot of conflation going on in that statement. one thing we know is we've got a very good record of co2. we can say with great clarity. humans will go back 300,000 years so we know we're the only generation of humans ever to live in concentration of co2 that at this high. that's a fact. now, you go further back in geologic time into the hothouse i taught you about, there are times in co2 was higher but our ability to measure co2 precisely as larger error bar. we think there are times co2 was as high as 2000 parts per
10:03 am
million several hundreds of millions of years ago in a different world that didn't have humans but in a world that had sea level was three or 400 feet higher as well. and part of the conflated climate story is being specific what you're talking about, and that particular example was a very misleading one. >> lets thank our speaker. [applause] >> thank you, dr. johnston. we will take a short coffee break. i encourage you to mingle. many posters, please visit that. it's west of the coffee and i encourage you to just chat and mingle. thank you. [inaudible conversations]
10:04 am
[inaudible conversations] [inaudible conversations] [inaudible conversations]
10:05 am
[inaudible conversations] [inaudible conversations] [inaudible conversations] [inaudible conversations] >> an all-day conference at the national academy of sciences in washington hosted by johns hopkins. they are talking a climate change and will talk about the policy debate on climate change coming up at about 10:30 a.m. eastern. we will have that live with it gets underway.

3 Views

info Stream Only

Uploaded by TV Archive on