Its coming. Hurricanes, floods, drouough, raging wildfdfires, snowstorms, and tornadoes. Is this purely nature, or are tthere manmamade, therefore controllable, factors at worork . A warmer, moister environment can intensify storms, creating heavier precipitation. And this Scientists Say is why human activities may account, at least in part, for the rise in extreme weather werere experiencing. The debate is setettled. Climate change is a fact. And when our childrens children lookok uin the eye a and ask ife didid all we could to leave them a safer, more stable world with new sources of energy, i want us to be able t to say yes, we did. [applause] as the obobama admininistratn renews itits commitment to ac the debate over Climate Change remains polarized. Climat scientist michael mann is a central figure in that debate. He was one of the scientists behind the development of the controversial hockey stick chart, which showed how temperature in the late Twentieth Century was exceptionally warm compared to the previous 900 years. This triggered a tax on dr. Mann and the Science Behind his work, all documented in his book the hockey stick and the climate wars. Michael mann, you write that in mid 1990s, scientisists were abe to begin to connenect the d dotn climate chchange. Could d you elaborate . We underrstood the basic science of the greenhouse effect nearly two centuries ago. Joseph fourier, the same e guy who discovered the law of heat conduction, understood that there was this greenhouse effect. So o weve known for soe time that the greenhouse effect exists and that were increasing it through fossil fuel burning. By the mid 1990s, we had reached a level of formal certainly about that that we had not before reached. We could actually attach a number to it. In the second assessment report of the ipcc published in 1995, the ipcc concluded that there was now a discernible human influence on the climate. Now, ththeres an interesting ststory there. The language woud have beeeen stronger than just discscernible, but the d delegas of c certain participating natis like saudi arabia demanded that the language be watered down and discernible ended up being sort of a lowest common denominator. It was the one thing that everybody could agree on, the governments and the scientists. But we were able to say that weve seen the fingerprint now of human influence in a formal way. We could actually detect that human finngerprint in ththe patterns f Climate Change that we had measured. Given the seriousness of the issue, can you explain why there has been so little action by pololicymakers . Well, unfortunately, m my of our politicians are beholden to fossil fuel interests. I mean, lets make no mistake here. Were talkingng about taking g n the most powerful indndustry tht evever existed on the face of ththe earth, t the fossil l fuel indndustry. Theyve chosen to fight back using hundreds of millions of dollars, for example, in the u. S. To fund what, without exaggeration, is the greatest disinformation campapaign ever run. In fact,t, there was a memo that was published in 2002actlly, it was leaked. Itit was a leaked mo from a republican pollster named frank luntz. And he was advising his clients, essentially fossil fuel interests, that back in 2002, there was this closing window. The public was now becoming cononvinced by thehe Scientific Community that human caused Climate Change is real. Anand if they were toecomome convinced about this, they would demand policy actions be implemented, actction be taken. But whatat luntz said wawas that theres still a window of opportunity left, according to his polling, according to the focus groups that he had done, to confuse the public, to cloud their understanding of the issue, to try to make it seem as if the science i is stil fiercely contested. And what he said was as long as the public thinks that scientists dont agree, that there isnt a scientific consensus, they can be convinced that it might be too costly to take action. And so thats exactly what the forces of Climate Change denial have chosen to do ever since. Theyeyve doubled down, if you will, in this campaign of disinformatation. I want to do my part on Global Warming. All yes on 23 says is. The effort through televisn advertisising, throuough the cultivation of s socalled expes who attack the science, talking hheads, the cuultivation of talking heads who o appear on tk radio, who appearar on cable televisi, theyve creaeated this very elaborate network of think tanks and advdvocates to create confusion in the publilic mindset aboutut this issusue of human caused Climate Change. So what were seeing here is a drastic change in climate, arent we . Well, climate has always been changing, but this is nothing to do with man. I have made a case, a very solid, sciencebased case, against anththropogenic globalal warming. And me ththinks someone is playing fast and loose with this whole subject. Yes, they arare. I meaean, basically Global Warming causes less snow except when Global Warming causes more snow. It causes less cold except when it causes more cold. If were going to o nalize producers of carbon monoxide, then we allevery time we exhale, weere breaking the e. Its gettingng warmer, you know, in n jupiter, a and theyt have any y suvs drivingng aroun jupiter. They said there were gonna be more tornadoes, more hurricanes, no ice in the arctic, increasingly hot weather. You have to stand up and point out that every year now for 15 years, theyve been wrong. The dreaded polar vortex. Do you know what the polar vortex have you ever heard of it . Well, they just created it for this week. All they need to do is to convince e the public that the science is uncertain. And thats why youll find some of their advocates who will deny that climimate change exists, dy the science altogether, but others who o willwho are somewhat more surreptitious in their attack will concede some of the scientific evidence, bubt will say that theres too much uncertaiainty, that the impactss might be sububsttially smallller than what the scientists who study impact say. So there are theese various lines of attack from denynying clClimate Change outright to simply contesting that its a problem. The only commonality being the argument that we donont need to t transn away from our reliance on fossil fuels, an argument, thats of course, thats very convenient to the fossil fuel interests who are fundining all of this disinformation. You talk aboutut the scientization of politicscs. Wht exactly does that mean . One of the other things that theyve done is to coopt politicians, like james inhofe, senior senator of oklahoma who has declared Climate Change to be the greatest hoax ever perpetrated on the American People while it continues to ravage his state because indeed oklahoma has been at the front lines of the impacts of Climate Change on the u. S. The record drought, the record heat that theyve seen in recent years. But, you know, other politicians like joe barton, who was the chair of the house energy and commerce committee, a large number of politicians, sadly many of them on one side of the partisan divide, republicans in particular, whose campaigns have been financed heavily by fossil fuel interests and who are now doing little more than acting as advocates foror fossil fuel interests. Whn it comes to the question of, you know, passing legislation to deal with Climate Change, thats really the scientization of politics that i i was talking about. This idea thahat the underlying scientificic evidence is just a a politicaal footbtball to be contested as ay other political issue would be cocontested. And there are polititicians w whose job it iso contest that evidence. When in fact, you know, thats not the way s science is. There art two equally valid sides. Theres a reason that the flat Earth Society no longer prevails in our public discourse, because they were wrong. The earth isnt flat. We accept that. Gravity does exist. There are propositions in science. And, you know, ill tell you, if there was a vested interested, if there was a Huge Industry that woululd stantoto profit greatly if the theory of gravity wewere wrong, yoyou would see ththe theory of gravity being contested in our u. S. Senate. Talk about the hockey stick and why it became such an icon in the climatate debate. Well, its this curve that my coauthors and i p published now 15 years ago. We attempted to estimate the temperature of the earth back in time. Now, theres only about a centutury f widespread thermometer measurements a around the world. So we can only y documentnt from instrumental measurements, thermometers, how the globe has warmed over the past century to century and a half. And we know its warmed about a degree celsius, about a degree and a half fahrenheit. What the instrumental record d cant tell us is how unusual is a warming like that over ththat period of time. Cocould it be tt that sort of warming happens naturally over a century time scale . To try to address that andnd related questions a aboutw the climate had changed in the past, my coauthorors and i attempted to make use of what we call proxy climate records nattural archives like tree rins or corals or ice cores or lake sediments that tell us something about how the Climate Changed in the past. And often these records are available not just 100 years, but 1,000 years or even further back in time. And so we took all of the information that was available at the t time fromom records ofs sortrt, socalled proxy recocor, toto estimate how the temperatue of the earth, specifically the Northern Hemisphere where we had the most data, how the temperature of the Northern Hemisphere had changed over the past 1,000 years. And what we found wasalthough the estimates are uncertain, as yoyou can imagine bececause wee not working with thermometers, were working with these very imperfect natural thermometers like tree rings and ice cores. So theres this band of uncertainty. But even when you look at the band of the uncertainty back in time, you see that the recent warming is outside of f the range that e see over the past 1,000 years. Theres no evidence that a warming of this magnitude happens nataturally, at least as far back as w we uld go. It led to a chart, which depicts temperatures starting out fairly warm 1,000 years ago, getting colder as you descend into the depths of the little ice age, and then, of course, the rapid warming of the past century, the spike at the end. It was the shape of this long term cooling followed by this rapid spike that sort of resembles a particular sports implement, a hockey stick. And it got named the hockey stick. The curve was featured in the summary for policymakers of the third assessment report of the ipcc, the 2001 report. And it quickly became an icon in the climate chanange debate. Are the Severe Weather patterns were seeing today related to Climate Change . We e are seeing t the loadinf the weather dice is the way id describe it. You cant lolookt any one heat wave and say, you know, Climate Change caused that particular heat wave with any great degree of certainty because theres a lot of sort of natural variability in the weather, the vagaries of the weather. You can get unusuallyly hot days just from chance alone. You can geget unusually cold days from chance alone. One of the things you can do is tally those rolls. So these are random rolls of the weather dice. And the question is, are we loading those dice so that 6s are coming up more often . Well, it turns out 6s, by some memeasure, are w coming up twice as often as they ought to. And what i mean by that is if you look, for example, at the u. S. , you look at the rate in which we are breaking records for alltime warmth and you tally over all of the locations across the country, all of the days of the years for all of the, you know, hundred or so years where we have good data, and you look at how often we are breaking alltime records for warmth vs. Alltime records for cold, ok. In an unchanging climate, in ththe absence of human caused Climate Change, t that raratio shoould be one to one. You shoud break cold records as often as you break warm records. What were seeing is were now, if you look a at the past few year, for example, seeing warm records, alltime heat records, broken at 3 times the rate cold records are being broken. 3 times the rate you would expect from chance alone. Thats actuallyly like rolling 6s6s the timmes as often as you would expepect. So rather than rollilg a 6 one in 6 times as you would expepect fromom a fair die, 6s e coming up half the time, so every other roll is a a 6. Is climate c change happening faster than we expecected . The current trajectory that were on leads to the conclusion that within a matter of a couple of decades we may see icefree coconditions in the arcticic at the end of the summer. This is something that the climate models predict shouldnt happen for another 60 years, till the endnd of the 21st centutury. And indeed nature seems to be on a course thats faster, thats momore dramatic than whatt the climate e models p predict. E are alalready obseserving and measuring a decrease in the amountt of ice in the Greenland Ice sheet and the west Antarctic Ice sheet. Now, the climate models have predicted that we shouldnt see that for many decades to come. And a key distinction here is if its a land ice sheet, a landbased ice sheet, then when it melts it actually contributes to global Sea Level Rise. Thats not the case for sea ice, but it is the case for the continental ice sheets. And so the fact that were already measuring losses of ice from these major continental ice sheets means that theyre contributing to Sea Level Rise faster, once again, than climate scientists projected them to. Can we say how soon its gonna start causing problems for people who live nearr the seashore . Thereres a credible body of work now that suggests that t if we continue with business as usual fossil fuel emissions, tthen by thehe end of this cent, we could see as mucuch as two meters, 6 feet of global Sea Level Rise. Now, that would bee catastrophic for many coastal regions. Fofor the u. S. East cot and gulf coast, island nations around the world, some of which would literally be submerged by that amount of Sea Level Rise. The ipcc makes a far more conservative statement. They state an upper bound of about a meter, about 3 feet. And s o once again an e exampe of where the ipcc arguably has been overly conservative. Some, as myself, have argued that partly thats just due to the culture of science. Scientists tend to be reticent. We dont like to make strong conclusions that we have to withdraw at somome later time. D theres also a component, i believe, due t to the pressure, the outside pressure, the critics, the very well fundeded and well organized effort to literally y discredit the sciene of Climate Change, sometimes by attempting to discredit the scientists themselves. I myself have been a victim of that. And in the face of all that pressure and those attacks, i thi t to some eent t the ipcc has actually w withdrawn a bit d theyve been more guguarded, moe conservative, more reticent in what theyre willing to o concle than thehey really shoululd be n the evidedence. Arguably, youou know, if it is indeed the ipccs role to advise governments on the potential for dangerous anthropogenic interference with the climate, which is what the ipcc was originally charged with as their mission, arguably, you shouldld not sort of downply thee higher r end scenarios if theyre credible, even if theyre lolow probability outcomeses. Mitigating climate chahange, dog something about ouour carbonon emissions is a a planetar ininsurance popolicy. And in gug the terms s of that ininsurance policy,y, we need to be fococusg on some of those potentitial, me exextreme catatastrophic o outc. If the ipcc c systematicically downplays those outcomes, then it doesnt serve that larger process of societal Risk Assessment as it should. If the changes are becoming so visiblble, why isnt t the pc more readily accepting Climate Change e as reality . Unfortunatately, one of the lessons of sort of the battles overer environmnmenl protection in the u. S. This century is that unfortunately a problem often has to reach crisis proportions before policymamakers are willing to a, often because there are vested ininterests whoo are lobbying heavily for actions not to be taken. And this was the cacase, for example, with acid rain where, you know, we committed to far worse environmental impacts of acid rain than we should have because the coal industry, whose emissions were causing acid rain, fought back fiercely against any policy action to deal with it. Ozone depletion. Once again, it totook us decades to act. We knew that the problem exiisted back, you know, inn the early 191970s. It took until the, you know, the montreal protocol in 1984 for us to actually take policy actions to prohibit the production of these substances, chlorofluorocarbons, that were destroying the ozone layer. And perhaps the best example was that, you know, eenvironmental pollution of our l lakes and rivevers. The Cuyahoga River i n ohio, it took that river catching on fire. It took a river catching on fire for the u. S. Public to say wait a second, we have a proboblem he we need to do something about. T. So some of us, you know, think that we may unfortunately need to have that cuyayahoga river moment in the e Climate Change debate before we will act. Sosomething so undedeniable that even the e most well funded, well organized Disinformation Campaign cannot convince the public not to believe what theyre seeing with their own two eyes. When you talk to other scientists and urge them to get into the fight, do they explain their reluctance . What i perceive is that this problem m is statarting to solve itself f naturally through sortf generational change. Many of the younger scientists that i talk to, you know, graduate students today, young post docs, they grew up in a different environment. They witnessed the attacks on science. To many of them, it upset them. It upset them that scientists were being attacked for simply speaking truth to power. R. And it sort of energizd thehem. And they come in wantntg to do o something abouout this. I have the sense that theres a much greater enthusiasm for public o outreach and communication among the younger scientists that are coming into this field and it may have been an inadvertent byproduct of the attacks against the science. I ththink its actually led to sort of a new breed of scientists s who comes in wantig to do science, cause, you know, thats what we really all lovove doingng is science, but recognizing that thereres also a roleleor speakining out, for communicating the sciencnce. If we can continue our upward trajectory in fossil fuel burning, what will l the plant look like at the end of the century . Qualitatively speaking, if you look at impapacts on human health, water availability, the human water resources, food resources, land, the global economy, pretty much every sector of our lives, of human civilization, what you see is a business as usual fossil fuel burning scenario by the end of the century gives us hihighly negative impacts across the boards in all those categories. I forgogot to mentin biodiversity. A potentially large scale extinction of spepecies. Some of these we can quantify economically, or we can try to. Some of them we cant even qualify how important they are. What is the value of the earth . Well, i its infinite because if we destroy the earths environment, there is no plan b. There is no planet b that we can go to. How do you put a cost, you know, on the health of the environment . Arguably you cant even do so. And in fact, its that principle, that its an infinite cost, when we Start Talking about those sorts of scenarios that leads some people to conclude that the precautionary principle applies here, that the potential imimpact of what were doing is so potentially harmrmful to us, to other livivg things, to the planet that its almost obvious that we need to mitigate this problem, that we need to take actionsns now to avert t those catastrorophic futureses, potential futures. Many people believe that truth will prevail over time. But do we have enough time left . So theres an urgency to this problem now unlike any time in the past. And there is still time e to avert catastrophe. Ththats ththe good news. Thehed news is there isnt a whole lot of time. And what it means is we dont have another 5 or 10 years to debate e in our u. S. Congress whether or not climate e change exists. We e have to be debating right now what were gonna do ababout it. Michael mann, thank you very much. [applause] Tom Goldtooth this is my home. This is our home right there. Its the mother earth. Everything around here has life, has spirit. Theres spirit to the trees, the ground, these plants, even this air and the wind, the wind that blows. [applause] oh. [speaking native language] hello, all my relations. [speaking native language] [speaking native language]