 Thank you Jim Yes as faculty chair of this year's conference the last couple weeks have been all consuming with Nobel conference and This was readily apparent at dinner the other night when my eight-year-old daughter told the following joke This will take a little audience participation, but I think you'll know what to do so Joe goes knock knock No bell No bell so I knocked So she got tired of me talking science and I'm not as clever as my as my eight-year-old daughter, but it is my distinct Privilege to introduce dr. James Hansen Being the humble man that he is he hinted to me yesterday that yesterday that he would like a short introduction and I will oblige Being one of the most famous scientists in the world. He hardly needs an introduction One is quite well known when with a name like James Hansen you can still be readily googled as a college student at the University of Iowa Dr. Hansen was attracted to science and research by James Van Allen space science program in the physics and astronomy department He received all of his degrees from the University of Iowa receiving a BA in physics and math with highest distinction in 1963 and eventually a PhD in physics in 1967 He began working for NASA after obtaining his PhD and was a very productive scientist working on light scattering by clouds and other important planetary sciences he became interested in climate change in 1976 and Published a paper in the journal science entitled greenhouse effects due to man-made perturbations of trace gases Since then he has published dozens of papers on climate change including an astonishing 16 articles in the journal science Students who have taken my environmental chemistry environmental studies courses know that I hold dr. Hansen's climate models in very high regard I model whole ecosystems like lakes and wetlands Dr. Hansen models the whole globe and his climate forcing models I find to be there very scientifically rigorous yet elegantly simple in their presentation and are readily accessible to virtually all audiences a Quote from his website states the scientific excitement in comparing theory with data and Developing some understanding of global global changes that are occurring is what makes all the other stuff worth it The other stuff is all the attention his research has garnered from the media It is very clear however after spending the last few days with dr. Hansen that he does not seek this attention, but rather he seeks scientific understanding and clarity in his work The attention has come because of his extraordinary science, and he is that he has conducted and the relevance of his topic to our world It is very clear after spending a little amount of time with dr. Hansen that he loved science, and I can honestly say That talking science with dr. Hansen the last few days has been one of the greatest thrills of my professional career Currently dr. Hansen is head of the nasa Goddard Institute for space studies in New York City a post he has held since 1981 He was also an adjunct professor in the Department of Earth and Environmental Sciences at Columbia University Dr. Hansen and his wife Anik who has joined us at the conference have two children and three green three grandchildren The newest of which is only six days old It is truly a pleasure and honor for us to have dr. Hansen at Gustavus. Let us welcome dr. James Hansen Thanks very much. It's it's a great honor to be able to speak to you today there's a a large gap between What is understood about global warming and what is known about global warming, and I mean what is understood? by the relevant scientific community and What is known by the people who need to know and that's the public and policy makers and the result of that is that? We really are at a crisis point It's hard for the public to understand this because we don't really see much happening and the climate changes that have happened are At least the magnitude of the global warming is small in comparison to day-to-day weather fluctuations but And I'll try to make this clear Why it has become so obvious that we we do have a crisis now It's partly related to the inertia of the climate system. The ocean is four kilometers deep It takes the climate system a Long time to respond to the changes that we're making in atmospheric composition it takes a few decades just for half of the response to occur and A few centuries for most of it to occur Part of the problem is that there are Positive feedbacks it become clear there. They're negative feedbacks and positive feedbacks that can amplify or diminish The four scenes that we exert on the system But what has become clear is that positive feedbacks predominate in the climate system And that's the reason why if you look at the long history of the earth it has had huge fluctuations in climate and for example, we're now seeing in the Arctic and a case where Because of these positive feedbacks There is the danger that we will pass tipping points of the climate system and then get very large Rapid changes and and we see one of these happening in the Arctic now as the Arctic sea ice begins to melt it Exposes darker ocean which absorbs more sunlight and that amplifies the warming and then the ice melts all the faster the big dangerous Tipping point would be if One or both of the large ice sheets on Antarctica or Greenland would begin to disintegrate and Get out of our control because it could cause sea level change of many meters in a short time period now It's important to emphasize that there is a positive side to the the new realization that That we are close to tipping points We're going to have to keep The climate forcing is much smaller than we had thought even a few years ago Even 450 parts per million of co2 is almost certainly dangerous And we've already increased co2 from 280 to 380 parts per million and it's increasing about 2 ppm each year That means and but it is possible there are actions that we could take that would make a lot of sense for other reasons and If we take those actions we can avoid problems that we had begun to think were inevitable things like the acidification of the ocean and Carbon dioxide is not the only climate forcing there. There are others which are Air pollutants that affect human health and agricultural productivity and we're going to need to reduce those so the The planet that we can see in the future if we do take the actions that we need to take is actually a very attractive planet and has Advantages over the present situation with a much cleaner environment and a stable climate, but The problem is I will I think try to make clear is that special interests Who are more interested in short-term profits are making it difficult to make this story clear The this is the Global warming in the last century Temperature has increased eight tenths of a degree Celsius. That's about one and a half degrees Fahrenheit With three-quarters of the warming occurring in the last 30 years It's not it As I say that's small compared to weather fluctuations which can be 10 or 20 degrees from one day to another and Even even if you average the temperature over a month The chaotic fluctuations due to the weather are Substantially larger than this global warming these are the temperature anomalies in The first several months of this year relative to a base period of 1951 to 1980 what so when many of us grew up And the reds and yellows are warmer than that base period and the blues and greens are cooler so you can see if you look at the United States that One month is cooler than normal and then one month is warmer than normal But if you look carefully you see that there's more area that's warmer than normal Than cooler than normal and if you average These anomalies over the first six years of this century then we can see the pattern of global warming and it makes sense It's what our models tell us it should look like there's More warming over land than over ocean because the ocean has this thermal inertia so it responds more slowly and The warming is larger at high latitudes and low latitudes because of the positive feedbacks Especially the fact that ice and snow melts and reveals a darker surface And the warming is larger in the northern hemisphere than southern hemisphere because there's more ocean in the southern hemisphere and Around Antarctica the ocean mixes very deeply so it hasn't at the surface. It hasn't changed temperature much yet So this warming is you know less than one degree Celsius so Why is that a problem? You know we talk about warming that's still in the pipeline there's another Half to three-quarters of a degree Celsius warming that's in the pipeline due to this inertia due To the gases that are already in the atmosphere even if we stopped increasing them we would get this warming and Isn't that a theory? Well, we know that that's right because we can see that the planet is out of energy balance There's more energy coming in from the sunlight than there is heat going out and the proof of that is the fact that the ocean heat storage the ocean is continuing to gain heat at a rate of about between one half and one watt per meter square averaged over the earth's surface and that implies that there's going to be an additional warming of about Half a degree or three-quarters of a degree Celsius But You know intelligent person can still ask the question do we really need to wrestle with warming in fact This is the question that was asked on national public radio by the NASA administrator the head of the largest science agency in the country And we heard the question asked yesterday by a famous geologist, which is a field that Is very familiar with the climate and People asked the question well, there were huge climate changes in the past So who are we to say that the present climate is the best climate? well in Fact the earth's history provides our most helpful information for understanding climate change and The implications of human made changes This is the temperature in Antarctica over the last 400,000 years with time running from left to right so the The hollow scene on the extreme right is the present interglacial period the warm period that we are living in That's about it's more than 10,000 years long. It's been all of Recorded human history is within that period But the temperature Is oscillates at this Southern hemisphere at in Antarctica by about 10 degrees Celsius between the depths of the ice ages and the warm interglacial periods on a global average and these variations occur over the whole planet on the global average the Variations are about five degrees Celsius between the ice ages and the warm interglacial periods About three or four degrees at the equator and then they're amplified at the at the high latitudes And there are big changes that go with these Global temperature changes. I should say that these Temperature record comes from drilling an ice core a core in the Antarctic ice sheet The Antarctic ice sheet is formed by snowfall piling up year after year and as it gets deeper It gets it compresses the lower part into ice and that ice Will trap bubbles of air so we can sample the composition of air as a function of time over this entire period and what we find is That when the planet is warmer There's more carbon dioxide in the atmosphere and that makes sense because a warmer ocean One of the major effects is simply the solubility of carbon dioxide in water decreases as it gets warmer It's not like your Pepsi as it gets warm the carbon dioxide bubbles out and There are also changes in the ocean chemistry which contribute to a Warmer climate putting more carbon dioxide into the atmosphere. So the changes in In carbon dioxide in the atmosphere are a movement of carbon from one of the surface pools to another The surface of pools of carbon dioxide include the atmosphere the ocean the soils and the Biosphere all contain carbon and and it can move from one of these pools into the other as I just described on Much longer time scales you can also have carbon moving between these surface pools and the and the solid earth from the weathering of rocks and from the earth De-gassing carbon dioxide through volcanoes, but in addition another the other curve on this plot is sea level you can see that When the planet gets warmer sea level rises and the changes are large. It's about 400 20,000 years ago in the last ice age sea level was about 400 feet lower than it is now so the Continental shelves all around the world were exposed and you could walk from Asia to North America across the land bridge For example and these these fluctuations in climate on these long time scales are As I will describe briefly later are driven by chain perturbations to the earth's orbit But I would like to put Those climate changes in an even longer time scale perspective. I think it's helpful to look at the earth's history on longer time scale If you go back a quarter of a billion years ago 250 million years ago The continents were all stuck together in the supercontinent, Pangea But they began to break up and move apart and by 65 million years ago at the end of the Cretaceous after the dinosaurs had when extinct the Location of the continent the continents were resembled their present Forms the North America and South America were closer to Eurasia and Africa than they are now, but basically they were at the the same latitudes as as they are now and The climate 65 million years ago was much different than it is now is much warmer More than 10 degrees Celsius warmer and there was no ice on the planet on Antarctica or any other place the I like to focus on this so-called centzoic era the last 65 million years because it's close enough to the present that The four scenes many of the four scenes are not extremely different than they are now We know for example that the brightness the sun is becoming brighter as a function of time the sun is burning hydrogen Nuclear reaction Hydrogen is being by fusion converted to helium and releasing energy and We go back four and a half billion years the Sun was 30% dimmer than it is now, but Over 65 million years the change in the brightness is about one half of 1% and Since the earth absorbs 240 watts per meter squared of energy from the Sun that means the Change in the brightness of the Sun is about one watt Per meter squared over This 65 million year time frame Any four scenes that are going to change the climate have to either be due to the energy coming in or some changes within the Atmosphere or some changes on the surface well the surface because the Continents were pretty close to their present latitudes the changes in the forcing due to the albedo of the surface Being different for ocean and land is a fairly small forcing less than one watt per meter squared on the other hand we have Measurements proxy measurements of the atmospheric composition Which tell us that carbon dioxide 65 million years ago was something in the one thousand two thousand parts per million that the greenhouse effect of carbon dioxide With that much carbon dioxide would be a forcing of More than 10 watts per meter squared So that's a much larger forcing than either the solar incoming radiation or the surface changes and So the a big factor in the climate variations during the past 65 million years is in fact that changes in atmospheric composition and We have a pretty accurate picture of what happened As you can see 65 million years ago India was still in the South Indian Ocean and it was moving north at a Very rapid velocity of about 15 centimeters per year that's half a foot per year Asia was retreating northward at a rate of about two centimeters per year so 50 million years ago India crashed into Asia and began pushing up the Himalaya Mountains and the Tibetan Plateau and That has been it has had a dominant effect on atmospheric composition because as these mountains rise up then the weathering process Deposits sediments in the ocean base on the ocean floor in particular carbonates which Draws down the amount of CO2 in the atmosphere. There's a What determines there's a balance that determines the amount of carbon dioxide in the atmosphere the Weathering of rocks and the deposition of carbonates on the ocean floor draws down CO2 and also the deposition of Organic materials Can't draws down Atmospheric CO2 the rock weathering is the bigger factor but the return path to the atmosphere is as Ocean floor is subducted under the continents It the metamorphic process Which converts this carbonates into basalt and other rocks Releases CO2 which comes out through volcanoes and springs in your Perrier water and and such things But at any time there does not need to be an equal balance between these depending on The rate of subduction and the rate of weathering and the rate of mountain building so this on the top curve is the Basically the temperature as a function of time over the past 65 million years up until 50 million years ago as India was approaching Asia and Africa was closing in on on Europe there there was substantial subduction of the Ocean bottom in the the water body Between these was called the tethys ocean and part of it was subducted and so there was Emission of carbon dioxide to the atmosphere which Caused does this show up? How do I do this like yeah? So in this region that in that time period CO2 was increasing and the planet was getting warmer But 50 million years ago With the beginning of the rise of the Himalaya Mountains From then on there's been a general cooling trend for the last 50 million years When we reached 35 million years ago It became cool enough that Antarctica began to freeze they're going to have ice on Antarctica and then with this tipping points and positive feedbacks it It went quite rapidly It Several million years later Probably because of negative feedback there was less weathering when Parts of the planet were covered with ice and carbon dioxide increased a couple of hundred parts per million and by the way when Antarctica began to freeze there was approximately 500 Plus or minus 150 parts per million of CO2 in the atmosphere But after CO2 had started to increase again then the ice on Antarctica melted so it's a reversible process it's and But then in the past 10 or 15 million years The planet has been cooling off rather rapidly and in part that is probably due to the rapid rise of the Andes Mountains during This last 10 to 15 million years the Andes have been rising at a rate of about one millimeter per year Which is one kilometer per million years? and so there's been extensive weathering associated with the rise of the Andes Mountains and that also has slowed down the subduction of Of the ocean floor under the Continental plates there, but let me so in summary the dominant Forcing during this centozoic era has been changed a natural changes of carbon dioxide The rates of that are of the order of a hundred parts per million per million years, but that's only one 10,000th of a ppm per year so human made Changes in atmospheric composition are several orders of magnitude faster than that and totally dwarf that natural change It also shows us how sensitive the climate is and that even 500 parts per million It was a very different climate than it is today now if I've in the middle diagram, I've blown up the last Three million years three and a half million years during which time the planet continued to cool off But you'll notice there are these fluctuations these regular oscillations in in the temperature The The quantity the the this record comes from an ocean core the there are Microscopic Animals living in the ocean for eminifera which are shelled Microscopic animals as they die they sink to the ocean bottom and the sediments pile up, but the Composition of their shells can tell us The temperature or a combination of the temperature and how much Ice there is on the continents and we we see that There are these regular oscillations of the temperature at a frequency of 41,000 years That frequency is Driven by changes of the Earth's orbit and in particular the tilt of the Earth's Axis which is about 23 and a half degrees now To the plane of the orbit, but it wobbles by plus or minus one degree with a frequency of 41,000 years and as the tilt is larger it exposes the South Pole to more sunlight and six months later the North Pole to more sunlight so that as the tilt is larger Ice melts, and that's exactly what we see the planet The amount of ice on the planet decreases and the planet gets warmer with this 41,000 year periodicity With If we look at still In the bottom graph I've blown up the last 425,000 years So you can see these fluctuations in more detail and by By this time in the late Pleistocene the planet had become so cold that ice in the northern hemisphere during the ice ages Covered almost all of Canada and even came down into the United States and covered Minnesota among other regions and In so doing it made the problem a little more complicated because It made the two hemispheres Asymmetric the southern hemisphere doesn't have any land at these latitudes Comparable to Canada and Minnesota, so it then the problem Also the eccentricity of the Earth's orbit and the date at which the earth is closest to the Sun Comes in to play and the periodicity is no longer a simple 41,000 years, but it involves 23,000 year periodicity of the Date at which the earth is close to the Sun and 100,000 year periodicity of the eccentricity, but In any case we have Very detailed information on the climate changes in the past 400,000 years which allow us to understand the mechanisms for the climate change We know the composition the carbon dioxide in the top curve in the methane and the temperature as determined from these ice cores in Antarctica and if we can compare the current interglacial period with the last ice age 20,000 years ago and We know the changes both in the atmosphere There was enough greenhouse gas Change to cause a forcing of about two and a half watts per meter squared and the change in the Albedo or reflectivity of the earth's surface Changed the amount of sunlight absorbed by the planet by about three and a half watts per meter squared So the total forcing of about six and a half watts per meter squared Together with the observed temperature change of five degrees Implies the sensitivity of about three quarters of a degree for each watt of forcing and We can now check that sensitivity for the entire 400,000 year period because we have measurements of sea level change During that period By the way, I should point out that the sea level change on this top graph the Sea level has been remarkably Constant for the last 7,000 years the planet is warm enough to keep ice off of Canada But it's cool enough to allow Greenland in Antarctica to maintain their ice So we've been in this nice happy zone where sea level has been remarkably constant and About between the last six and eight thousand years it became stable Six or seven thousand years ago and perhaps not coincidentally The first cities came into being at that time the Coastal zones in order for To have high biological productivity in the coastal zones the sea level needs to be stable and All of the with the exception of Jericho all of the cities that developed at that time were on Coastal regions where Fish provided a source of protein and nourishment that allowed more complex Civilization to develop but in any case the Climate forcing due to the greenhouse gases and the sea level change and therefore the ice sheet change Can be calculated accurately and when we multiply those four scenes by the Sensitivity of three-quarters of a degree for each watt of forcing we get a very good agreement as shown in the bottom curve between The calculated temperature change and the observed temperature change So the mechanisms even though the instigator of the These climate variations with changes in the Earth's orbit the mechanism by which the temperature changes is Change in atmospheric composition and change in surface albedo. Well now Those mechanisms are totally under the control of humans The CO2 and methane are now increasing far outside the range And I've expanded the timescale on the right for the last century just so you can see the change but These gases are now far outside the range that they have existed in millions of years And the temperature is beginning to respond on the timescale that we expected to respond So the implications Are I'll skip to the bottom one to keep on schedule humans are Now in control of the mechanisms for global climate change Without any question For better or worse We can look at this in some greater detail because The humans are not only increasing carbon dioxide and methane. They're also changing other things amount of black carbon or soot in the atmosphere and there are natural fluctuations in the Sun's brightness due to Sunspots In effect and there are Fluctuations in the amount of particles in the stratosphere due to volcanoes occasionally going off But we have pretty good measurements of these if we Put all of these four scenes into a climate model and calculate the temperature change over the last century We in fact get good agreement with the observations, which is shown by the blue asterisks and We can use the same models to extrapolate into the future Energy departments tell us that we're going to continue to burn the fossil fuels and burn more and more each year If we do that we get these business as usual scenarios for the future the dark blue line Which would tell us that we're going to get warming of of the order of three degrees Celsius this century I like to contrast this with a scenario that I've defined I call the alternative scenario in which We begin to slow down the rate of fossil fuel burning and at a Rate that allows global additional global warming to be less than one degree Celsius Based on the most recent evidence, I think that even this alternative scenario with warming less than one degree Celsius is potentially dangerous in the sense of It's likely to cause ice sheet instability but the point is that all You know 180 nations have agreed that we should Stabilize greenhouse gas emissions at a level that prevents dangerous climate change and the United States was one of the first countries to sign this framework convention, but the problem is no one knows what dangerous is I think that the critical factors Defining dangerous should include global sea level because if the ice sheets become unstable and Begin to disintegrate that will be an irreversible process which would be out of our control and the Potential implications are enormous and likewise the extermination of Species is also irreversible So that I think deserves special. They're also large climate disruptions on regional basis, but I Think the sea level and species are perhaps the most important issues Greenland the melt on Greenland where absurd we observe is increasing over the last over the period of satellite data the last 25 years and The melt that occurs Does not in general go run off the edge of the ice sheet It finds a low spot on the ice sheet and burrows a hole to the base of the ice sheet and There the water serves as a lubricant which makes the ice streams move Icebergs these giant icebergs to the ocean much more rapidly and These ice streams have more than doubled in their speed during the past decade There was a question are Global warming also causes the ice sheets to grow faster because you get more in a warmer atmosphere has more water vapor and therefore greater snowfall But we now have beginning in 2002 we have this remarkable satellite Grace which measures the gravity field of the earth with with such high precision that we can Observe changes in the mass of the Greenland ice sheet And the Antarctic ice sheet and what we see is that during the winter the ice sheet gets heavier as more snow Piles up but during the spring and summer and fall it loses mass And the trend is now clearly downward with a loss of about 150 cubic kilometers of ice per year Which is a dramatic change from even five or ten years ago when it was closer to mass balance and That there's a similar loss of mass from the Antarctic ice sheet So the sea level is now going up at a rate of about Three and a half centimeters per ten years per decade that's still Not a dramatic rate of sea level change, but it's double what it was just 15 years ago and it's in that itself was double from a century earlier and the problem is that ice sheet disintegration is a very non-linear process if it Doubles a few more times Then it's likely to get out of our control and end up with Much larger sea level rise in fact we know from again from the history of the earth that when ice sheets disintegrate They disintegrate quite rapidly 14,000 years ago sea level went up 20 meters in 400 years, which is one meter every 20 years. That's a Rate of sea level change, which we really Is almost unimaginable the impact of that because there are so many cities around the world that are located Within a few meters elevation of sea level that would include well many European cities Amsterdam Stockholm and Copenhagen and but in the United States the Cities up and down the east coast and almost the entire state of Florida would be underwater if we If we have three degrees of global warming the last time the planet was that warm in the middle Pliocene Sea level was about 25 meters higher Other places like China has 250 million people who are located within 25 meters of sea level And almost an entire nation of Bangladesh would be would be underwater I think our best way to judge how much warming we could tolerate is Looking at the history of the earth This shows the last million years We don't have good measures of global average temperature over this time period but we do have measures in certain regions where we can take these ocean cores for example and the Western Pacific warm pool is a particularly important region because that's the region which determines the Transport of heat to higher latitudes both in the ocean and in the atmosphere and the Indian Ocean is also important because that has In the period when we do have global data It has the highest correlation with global mean temperature And if we look at these regions we see that the warming that has occurred in the last century has already brought us up to a point within less than one degree Celsius of the warmest period in the last million years and and there were previous interglacial periods that were warmer than the present one, but only about one degree warmer and The changes the climate changes in these warmer interglacials were Probably something we could deal with although the sea level changes are not negligible of the order of two to four meters of sea level change, but As I say if we went back to a planet that was three degrees warmer then the changes are Are really staggering? I Yeah, you know One so let's say we decide all we're we're gonna wait a while and see what happens So if sea level went up one meter well, we could say maybe there's something we can do about that We'll we'll make a dam and make a lake where we store one meter of sea level. Well, just to give you an idea of What that would require If we wanted to make a lake in North America, we could make these dams Which would need to be about 200 meters high to make Hudson Bay bigger But it would take a lot of Canada. I'm not sure the Canadians would be willing to To give that up. Well, we could also Make one in Asia That would require a dam about 240 meters high Again, there are quite a few people who live in that region. So I think we might have a hard time convincing Those people to allow this lake and that would only take one meter of sea level So if we're going ahead if we let the ice sheets Lose one meter of sea level. They will probably have a few more meters on the way So we really need to keep them stable Also, there's the question of the impact of climate change on species we Of course climate has changed by large amounts in the past and there were Previous times in the Earth's history when there were global warming of five or six degrees Celsius and we know that those Global warming there was large. There were mass extinctions associated with these climate changes as much as 90% of the species on the planet and other species come into being following that but of course it takes hundreds of thousands and millions of years for New species to develop and that's a time scale which humanity cannot even imagine. I Think that most of us would prefer to keep Creation and the species that that we have had during During the past several thousand years but for example in Species will respond to climate change by attempting to migrate because they can in general live within certain Climatic zones so if the climate begins to change they will migrate to stay within that climatic zone but of course those at high latitudes don't have any place colder to migrate to and those In alpine regions as the planet gets warmer a temperature line moves up the mountain and That's happening in the Southwest United States. We notice the so-called Islands islands in the sky the green areas on mountains in the desert regions are moving up the mountains Tends to work by forest fires burning the lower part of the forest and then it simply can't recover because the climate has changed And then the forest won't regrow there So the species that live there in effect are also being pushed off the planet but in general the a given temperature line is now moving Forward at a rate of about 50 to 60 kilometers per decade, which is about 35 miles per decade and so far that the movement has been in general smaller than the the zones the That different species live within so it's not a big problem But if we go down business as usual that rate of movement will double by the end of the century and The total movement of a given climatic zone will be so large that it undoubtedly will drive many species To extinction especially because there are other stresses that humans are placing on on species And we're limiting their ability to migrate because we've taken over so much of the planet So the the big issue is Carbon dioxide is the single biggest forcing and the thing about it is that When we put a pulse of co2 into the atmosphere by burning fossil fuels half of it appears to disappear within 10 or 20 years because It's taken up especially by the ocean but then The uptake slows down because in effect the co2 in the ocean exerts a back pressure on the atmosphere and even after 500 years About one quarter of the co2 that we've put in the atmosphere is still there and That's the problem now if we look at where this co2 comes from the we heard yesterday that oil may be peaking already and There there are some disagreements about how much a new oil might still be discovered but Oil by itself cannot take carbon dioxide to 450 parts per million and It's practically impossible to capture co2 coming out of the tailpipes of vehicles and we're not going to be able to tell Saudi Arabia or Russia not to mine their oil and sell it So the real issue comes down to coal and what's going to happen as oil does run out Are we going to try to squeeze liquid fuels out of coal or out of? tar sands or our tar shale That's what we really can't afford to do we we could keep co2 less than 450 parts per million if we would just agree That in the future we would begin to phase out the use of coal Except at power plants where we capture the co2 and sequester it That in fact is the principal thing that we would need to do in order to stabilize climate and That may seem like a very difficult thing to do, but if you compare it to what we did say in World War two It's really not that impossible a challenge To agree that we would only use coal in that way It's also important that we stretch the conventional oil and gas because otherwise We're going to run out very soon, and and we won't be ready with the new technologies that don't require Don't require oil so I think a Second essential element in a solution is to have some incentives that incentives for conservation and Energy efficiency and renewable energies So that we can work in the direction of the life beyond fossil fuels and Because we are likely to pass the dangerous level of co2. We're going we should also consider reducing the non co2 climate for scenes which are Smaller than co2, but not negligible and we may have to find some ways to draw down atmospheric co2 which is possible with improved agricultural and forestry practices and by burning biofuels in power plants where we capture the co2 and then sequester it and that's why I like to point out that the Midwest could come to the rescue of the of the coastal states by if we could develop biofuels as we talked about yesterday ones which Are can actually draw down the co2 both by having the no-till agricultural practices so the store more carbon in the soil and By growing those types of biofuels which are not so energy-intensive Cellulostic Fibers for example So the summary there's there is still time in my opinion to avoid The disastrous climate effects and to keep global warming Well under one degree Celsius additional warming But in fact that Path is not being pursued I think even if we go one more decade down business as usual Path with co2 emissions continued to increase one or two percent per year then it becomes impractical to get on to a path which would keep Additional global forcing less than the amount that's needed to keep warming less than one degree I Could show that quantitatively, but I really don't have the time here, but with regard to responsibility for The global warming you now hear that while China is passing us and is emitting more CO2 than the United States well that is true with current emissions, but that is not where the responsibility for global warming lies Instead the warming depends on the cumulative emissions over time Because of the long lifetime of carbon dioxide in the atmosphere and the so the United States is responsible for more than three times as much as any other country and we're going to continue to be the primary cause for many decades into the future and Even if you look at per capita emissions We are the highest of any country and several times higher than the developing countries So it really would make sense to look at this problem the way we did the previous planetary emergency when It was suggested in the early 1970s that chlorofluorocarbons might destroy the stratospheric ozone layer There was an immediate Halt in the in the building of any more chlorofluorocarbons plants, and that was possible because people stopped using spray cans with CFCs for hairspray and deodorants and and Privilege uses like that and then ten years later when the ozone hole was discovered We realized it really was a problem then there was this Montreal protocol which Phased out their production of CFCs in the developed countries within the next few years and it gave China and India and the developing countries an extra ten years because they didn't have refrigerators yet And they needed CFCs for refrigerators, so we let them Continue to produce CFCs for ten years in addition But then they had to also phase out CFCs and we helped them with the technology for replacement chemicals that did not produce chlorine and the problem Solved or is in the process of being solved Chlorine is now beginning to decline in the stratosphere and the ozone hole should recover over the next few decades So this was a success story where the scientists the media the public And the government deserved credit because the government the US took the leadership role in defining This solution special interests Argued that the science was not right, but after a few years they changed their mind and decided they would Develop new chemicals that did not destroy ozone But in contrast in the global warming story, I think that scientists have not done a Good job of making clear that just How serious the problem is and the fact that that we really are talking about a different planet if we don't do something and The media has not has continued to confuse people I Think that both the media and the government are very strongly influenced by special interests who have Are more interested in their short-term profits than the long-term future of the planet and as a result of public has So I think to some degree all of these parties deserve some of the blame but except for the Children and grandchildren and unfortunately, they're the ones who are going to have to pay Because this climate change is something that the impacts really come on on Decadal timescales, and we're just beginning to see them now, but they're going to become much larger if we don't get on a different path So it see it seems to me that by far the most urgent action is we should have a moratorium on new coal-fired power plants because they if you build these new plants their lifetime is Several decades and they are coal is the Present and in the past has been the largest source of CO2, but in the future It's all the more true because we're going to run out of oil So we need to move in in this direction of efficiency and renewable energies But I think in order to do it at a pace that is necessary that people are going to have to make clear That that this is important to them Otherwise Congress is not likely to act decisively so I'm actually suggest that when You talk with candidates for office that you should ask them whether they're willing to agree to these items and a declaration of stewardship For the earth and all of creation and first of all are they willing to support a moratorium on Dirty coal plants that do not capture and sequester CO2 and that doesn't mean plants that might sometime in the future Capture CO2, but you shouldn't build them at all unless you have the technology to capture and sequester the CO2 and What's very difficult for a politician But it's essential I think that and I think the public would understand if the problem is explained you're not going to Encourage the technologies that are needed unless you have an incentive for them And that means there should be a gradually rising price on carbon emissions And it doesn't need to be done in a way that hurts the small Small fellow, but there does need to be a price on carbon emissions and the end result with Will be It's not it's not on the contrary To the statements often made that it will harm the economy. I think it's clear that the new technologies actually will stimulate the economy and provide many Good high-paying jobs, which are not inferior to coal mining for example But even coal mining is is coal is still okay provided you capture the CO2 and sequester it So my I think that it is very clear that We understand the climate problem well enough to know that we are on the verge of hitting tipping points and we have the Example of what's happening in the Arctic right now, and there's the potential that we could Lose control of the future of the ice sheets if we don't begin to slow down these foreseats I think that we are that we are in a In a struggle Against ignorance and there has been progress with the In the media recently but We still have these misconceptions which are are very Surprising and it's very unfortunate. It seems to me that this has become political. It seems to me that conservative people should Be at the head of the line as far as preserving Well, let me say that Bottom line it seems to me is that the climate situation is now clear But we have not made it clear enough to the public And I think that we we are in a struggle against ignorance with I think the future of the planet and the future of creation being at stake and I think that we have failed to make the situation clear partly because Scientists are poor communicators I think but perhaps even more because of the role of special interests and I and This is something which I Mentioned for the first time in a talk that I gave two years ago at the AGU meeting Which was sort of an unusual statement to to raise To make a comment about the role of special interests and the Understanding as at least the public understanding of this problem, but it seems to me it just becomes so Obvious to me that we were having a great deal of difficulty communicating the situation So I think we are also in a struggle against greed It's that's just my that's I know that's that's not a scientific Opinion is a personal opinion but I think that That we need to so I I don't quite know how to deal with this, but I've tried to Draw attention to the generational inequity because I think that the what I call the captains of industry also have children and grandchildren and I think that if they don't pay attention to that then Their children and grandchildren should ask them, you know what they're doing, but the problem that I find now is that the Industry and the captains of industry are now starting to say the right words But they don't really mean that so you get these advertisements from the big fossil fuel companies that sound like green They're becoming green, but I think you really have to watch what their investments are if they're not investing in clean energy and Renewable energies and things like that and if they're only trying to extract as much profit as they possibly can from fossil fuels then then they still don't really get it and until we pass that That barrier and get because the truth is the we have the ability to solve the problem and the We and the people who are in charge of these industries are very capable people They don't get to be CEOs without being capable people But until they really begin to address the problem in a serious way. I think it's not going to be solved Go stop there. Thanks. I also had a question about why we look like astronauts up here with the Headphones on and it's a Acoustical problem where if we don't have something like this, we can't hear each other So in the efforts to bring the best possible information to you we have this All right, as we usually do we'll begin by asking other members of the panel if they have questions or observations on dr. Hansen's top Dr. Ogden That was a wonderful talk I'd like to say maybe one thing about the last point about the role of the vested interests in making all this happen and Having talked to a lot of people for example in energy companies over a period of time in some of the energy companies Not all I'd say there is starting to be some moves in the right direction in terms of some actual Investments, I also get the feel low that the energy companies will essentially deliver whatever fuel we want and Some of them are most of them all of I guess are waiting for the regulatory framework and or the economic framework to make Renewable fuels for example another in carbon capture sequestration more economic and once those rules are there They will play and they'll make money and they'll go through a transition in their industry and soon They'll be a money-making proposition again So I see it more of a sort of shying away from the transition in the absence of a consistent set of playing rules I agree That what we need is leadership if we had that the the many of the The industry would is capable of solving the problem, but you have to give them the incentives they're not going to Become money-losing operations Voluntarily, so you have to you have to set the rules up so that they can still make money I mean utilities are a good example It was mentioned yesterday you should have the rules such that they don't have to sell more energy to make more money There that's just one example, but there are many ways in which we could Set up the rules so that industry would then solve the problem, but we haven't done that Will yeah, I'd like to add a few things maybe ground proof in a way what Dr. Hansen said We run an expedition last year to Baffin Island Basically to put a cultural face on global warming in addition to science Baffin is in the Eastern Canadian Arctic very mountainous island about 1400 miles across and We traveled with the Inuit people three men that were in their 50s and 60s all born in either South Hudson Igloos and along the way We came on five villages in access by either dog team or or airplane and I interviewed or talked to at least a hundred elders and hunters and women in these communities and to get their viewpoint of global warming and of course When your livelihood Depends on the ice and the weather here. You're obviously very aware of it And over the last 15 years global warming has been affecting that area, but in particularly everyone says it's been Reshocking in the last five six years and how fast things are occurring. These are basically marine people. They live on Rely on the ice. They live on land but mountainous area there. So the hunting is not that good on land So they rely on seals and fish and walrus and so forth and some of the observations were you know, I'm a hundred percent was of course later later freeze ups where the freeze up would vary from two weeks to six weeks, but in that area they would get a freeze up normally and then the Temperature would drop into the ice box 40 below until around April time But what happens now with freeze up is they get thick clouds Which stabilizes the temperature so it doesn't drop and then they get a lot of snow very unusual snow on top of sea ice then sea ice Makes it a very dangerous situation in fact number of the hunters there have lost their lives They've adapted now knowing what's happening earlier breakups, of course, which reduces the sea sea ice by almost two months Which again disrupts the heat balance of the globe. They all talked about the the ice Thawing from underneath they always said it was underneath from underneath and talking about the currents increasing on the fall They talked about stronger winds especially on the coastal area stronger winds some sleet and We've noticed that for sure that there's virtually no caribou along the coastlines here caribou was very common No science whoops or droppings and so forth the caribou migrated inland in the spring They would have unusual flaws and then freeze ups and they have a lemming little one small rodent animal That's the base of the food chain for a number of animals like the snowy all for example 100% Almost 100% of their diets from the lemmings when you get a freeze up a thaw in a freeze These lemmings die off and along with that goes the owl and then the wolf and the fox relies on the Lemming and they then go to the seal pops which then competes with the polar bear And I just conclude I could go on a whole list of this but In the summertime the Cura whales are coming into a lot of these communities Areas where there's ice almost all year around the Cura whales in our Pretty much eating up the seals they go into a bay and they'll harvest all pretty much all the seals the seals and The ice seal their ring seal would rely on the ice to escape from the Cura whales. So The global warming is definitely affecting These people that rely on the on the sea ice and and on the land So it's pretty obvious what's happening up there. Thank you. Dr. Jasco In my experience politicians Most politicians respond to two things First of all, they want to get reelected and second of all they want Campaign contributions to get reelected and to get reelected. They need votes We've been doing surveys of the American people and their attitude towards climate change for About seven years now at MIT and the Pew Center has been doing it for longer And it's only very recently that public attitudes have begun to change Where climate change is ranked reasonably high in terms of people's concerns Quite different from Europe And it seems to me unless we can convince the voting population that this is an important issue Politicians are not going to be reflecting it as an important issue in Their voting behaviors, so I I think there is a real educational challenge that that scientists and Educators face and in convincing the public that this is an issue that they need to be concerned about And an issue that they may be willing to have to pay for something but in return for benefits that exceed the cost Dr. Lind Well, I was going to say two things and Paul just said one of them So the only other thing I wish to add at this point. I guess in addition to saying Jim. I found that an inspiring Call to action personally But I would just like to reflect on this business of that Jim briefly brought up relative to what it means to be Conservative which it seems to me is risk averse and how this is maybe stating the obvious, but sometimes that's worthwhile How irrational our approach to risk is right now Jonathan Peele the former editor of Scientific American said 17 years ago in a book on this subject He began the preface of a of a of his book by saying with a book he edited By giving the following example saying imagine you were getting on a plane and the announcement came over the loudspeaker that you had that the plane had a 10% chance of crashing with everybody With complete fatalities you would do anything to get off that plane and Somehow when faced with other people at this table are more qualified than I am to say just what the probability of of truly Catastrophic consequences are but I got a hunch it's better than 10% the collective attitude is prove it Dr. Chew I Would I would like to amplify this business about conservatives at dr. Hansen professor when talked about There's another part not only to do the necessary things to avoid the risks that we see But also there's a larger part of conservative, which really means conserve what we've got conserve the earth Instead of conserving the wealth for a few and so And if we can get Republicans and Democrats to to embrace what the good parts of conservative mean to the large body of people in the world That would be a great thing Let's go to some questions here from the audience What is the timescale of the worst-case scenario for ice sheet meltdown and sea level change? Yeah, that's important matter and It's a difficult question to answer because ice sheet disintegration is an so-called nonlinear problem it Which means Goes slow for a while, but once you get these positive feedbacks working together then you can get sudden collapse, and it's Inherently difficult to say exactly when that will be but there's no I cannot imagine That if we stay on business as usual that it would not occur this century that we would have Significant sea level rise and by that I mean measured in meters of a few meters now That's different than what IPCC said, but you have to look carefully at what IPCC said They decided to leave the ice sheets out of the problem because they realized it's a nonlinear problem And they don't know the answer so they gave some sea level rise for Thermal expansion of the ocean and for mountain glacier melting and that comes out to be you know a Third of a meter or something like that Depending on how fast the warming is but by far the most important thing is the Stability of the West Antarctic ice sheet that it sits on bedrock below sea level So that if it begins to disintegrate it could go quite rapidly and it's got about seven meters of sea level so if we follow business as usual my answer would be it our children will see the will see this happen and That's why we have to get off the business as usual path another question here climate change skeptics are Fonda pointing out that historical records seem to show that warming actually precedes co2 increases Rather than co2 increases being the lead factor. Could you please comment on this relationship? yeah, if I Ever have a chance to write this all down clearly That's what I meant to show. I guess I didn't show the graph that on these historical changes the temperature Preceed temperature change preceded the co2 and sea level changes and for The because the thing that instigated the changes was the earth orbital changes and it takes then time to have these responses, but in the human case, but the mechanism For the temperature change the primary mechanism is the change in atmospheric composition Instigator was a change in the orbit, but the mechanism is the change in Atmospheric composition. Well, we have now taken over the determination of the atmospheric composition So that is now the forcing and it happens first and then the response depends on the Response time of the ocean Very straightforward physics and the time constant is decades to centuries That is a very unfortunate time constant because we don't see the effect immediately Instead it's coming in the next few decades. We've seen a part of it So those the sequences all make sense and it's different than the natural one We are now putting the stuff up in the atmosphere okay Question here about soot and particulate matter Says when Krakatoa blew up we had cooler weather for a while. Is that gonna happen again? Sure when we get a big volcano that'll happen again. In fact the last time we got a big volcano was 1991 and as soon as we saw that We we wrote a paper and Geophysical research letter and predicted that the global Temperature was gonna drop by a few tenths of a degree Celsius and it followed and we made a model Calculation of that in the real world followed that quite accurately so yeah, there are Positive and negative for scenes but those things just go up and down while the human thing is one direction and It wins out over those natural things on the long run. Okay, dr. Chiu I'd like to return back to the previous question to add to what Jim said It's absolutely true that the Astronomical changes in it initiated, but it is not clear Because there appeared to be feedbacks going on that are positive that if you just looked at the Temperature rise of sudden rises of six degrees There are feedback works that actually boost the signal considerably and so The astronomical changes started it and something kicked in Okay, now we're starting this and we're afraid something else will kick in and so that's Where it's not oh, this is all natural stuff. We're just you know along for the ride And there will are these feedbacks and that really has to be emphasized to our political leaders that that That sudden rise was not all due to an astronomical change Again if I really make the science focus more on the details of the science Yeah, the the sensitivity of the natural system turns out to be very high Because of those positive feedbacks and what we didn't realize until the last Few years is that some of these feedbacks that we thought were very Slow are actually faster than we thought and so for example. We're already seeing forests beginning to move north and That's a positive feedback because we're replacing tundra with forest and it's very dark It absorbs more sunlight and it causes more warming and that's why the earth's climate was so sensitive in the fast Because in the past because these positive feedbacks do dominate didn't have to be that way, but that's the way it is dr. Lin There was something that I was just reminded of that that Conversation up here at the podium that we didn't share with everyone yesterday But I think may be important for people to hear Jim if I understood correctly You made a comment yesterday to someone that we will never have another ice age That we have the ability to control that and I think there was a comment yesterday And if not yesterday, I know I've heard it in other instances that we're sort well the sort of cynical perhaps view is that you know We're we're banking warming potential against the next ice age or something. Would you please comment on that? I'm sure because we could we can avoid an ice age with the thimble fall of chlorofluor carbons the It's true that if there were no humans we would have headed for the next ice age on the timescale of thousands of years That's the natural cycles, but look at the four scenes that are required to do that They're a small fraction of one watt per meter squared. The system is just very sensitive, but slow well now Our foreseeing is as I showed orders of magnitude larger than the natural changes So we're we're in complete control and as I say it takes only a thimble fall of chlorofluor carbons too So we would of course never let that happen our problem is We're having a very hard time of how we can Think of avoiding the positive foreseeing that we're putting in the air because we're just putting so much co2 up there Okay Here's a question from the political scientists in the audience Jim Hansen has just been put in charge of US climate and energy policy. What are your first three initiatives? Well, the first one I mentioned was a moratorium on any new coal-fired power plants Until we have a technology to capture the co2 That that that would be amazingly effective Of the sea of the increase from 280 to 383 50 to 51 percent of that is from coal and in the future it'll even be a larger fraction So that's the most important thing, but then then the Second thing is you have to have a Gradually rising not very large, but gradually right and Industry has to know that in the future a carbon price is going to increase and then they will start to innovate and solve the problem But we have to have the leadership to do that so I would put in charge of a carbon price a czar Analogous to the chairman of the Federal Reserve somebody who is More or less a political and so he's doing what's best for the country and for the world rather than responding to politics of the moment and It would not be hard to avoid economic negative economic things if you had Such an approach rather than letting Congress try to change the rules have have A carbon czar And if you want a third thing then I would say there there are many Regulations such as the mentioned utilities where we should change the rules so that we Not only encourage innovation through a carbon price, but also make Rule you need you need some regulations on things like efficiency of appliances and vehicles and Utility profits things like that What about signing an international agreement that the world community would be a party to? Yeah, well obviously the the US should be Exercising leadership and you know is if we would do that it wouldn't be that hard to get China and India to come along because they have every reason they will suffer more from the climate change than we will But unless we Take the first step. I don't expect they're going to take a step Well, I think we should break for lunch here. I want to thank dr. Hansen for explaining something For the first time in my life and living in Minnesota all these years I Have an opossum living underneath my storage shit. I can't remember ever seeing an opossum in This part of Minnesota before I think I understand well We will reassemble here at one o'clock. Thank you very much