Climate I: Is The Debate Over?

and joining us now on the debate for the full edition in Paris France Richard linson professor of meteorology at MIT the Massachusetts Institute of Technology and in Vancouver British Columbia Hoddy delit abadi Canada Research Chair and professor of global change at the University of British Columbia we're grateful to both of you for being on our program this evening normally we have four or five or even six guests on this program but given the complicated nature of this topic we thought it might be nice to change it up and just have two guests for what we hope will be an edifying debate on perhaps the most perplexing topic of our day we want to from time to time during the course of our hour run some clips of a video put out by NASA in the United States as they set out the climate change issues and we'll start right now with our first clip just to set up our first question and then we'll participate in the debate right after that so control room if you would roll the first clip in the last decade the earth's temperature rose roughly a third of a degree fahrenheit since 1880 it's risen about one and a half degrees you might say the Earth's running a fever and scientists predict it's going to get much worse already we can tally the signs global sea level rose by over an inch during the decade almost twice as fast as the average during the 20th century artic summer sea ice declined by over 300,000 square miles enough ice to cover the states of Texas and Kentucky the vast majority of climate scientists say evidence for human-caused warming is clear but less understood is exactly how this warming will change the complex interactions between our planet's land water sky and the living organisms that inhabit our world ok gentlemen let's deal with the first issue which is just how hot is it and why Richard I want to go to you first on this if I can NASA's report says that from January 2000 to December 2009 it was the warmest decade on record and you have written that there's really no reason to be alarmed by that sometimes you say the temperatures go up sometimes down occasionally such as for the last dozen years or so it does little that can be discerned now there is a vast gap in our understanding between warmest decade on record and little can be discerned help us understand that discrepancy if you would from your point of view sure it's not a big problem you did have at least according to the records of surface data used by NASA the climate Research Unit in England and NOAA an increase in temperature from the late 70s through the 90s and that brought one to a high point in the record remember we're talking about tenths of a degree here we're not talking about anything very large it's a magnitude that you know almost all of us experience so I would say 30 times as much each day and so you reached a high point in the record in the 90s and it's done nothing since then please not statistically significant because each of these points has a fairly large error bar and so it's been flat since then and that's completely consistent with the statement that the last decade is the warmest and the record it just there's been no trend in it now you could argue maybe trends should be done over longer periods but and it should be longer than thirty years also say you know we're turning normal variations into the ancient notion of an omen we're scanning this small residue for small changes and speaking of them as though they were ominous signs of something or other how did you find that explanation persuasive oh it's an accurate explanation I think the problem we face is that it's a very complicated process leading to global average temperatures and to measure the anomaly on these small amounts and then to try and proclaim doom and gloom over the long term is oversimplifying the challenge I don't know for example how much of the stability over the last decade has to do with a huge amount of aerosols being generated in the newly industrialized Far East and all the other related stuff that can affect a signal on a year-to-year basis when many processes do affect it on a decadal and century length and as Richard and I have both said in the past sometimes in the zeal to grab people's attentions some of these more complicated processes are glossed over and that's certainly been part of the nature of the communication to the general public about which I'm perhaps not as happy as I could be because I do think there is public policy to be initiated but not perhaps using the kind of evidence that the nasa clip you just used would rely on but do you accept Richards position that you know little can in fact be discerned from the fact that this is the hottest decade on record and he certainly sounds much less perturbed about that than most of the climate change who say we're going to hell in a handcart or saying well I mean the question is whether the hottest decade on record is a harbinger of hotter decades in the future and what Richard is saying is that if I don't misunderstand him is that there is you know our predictive ability depends on our ability to be able to discern the anthropogenic processes and the natural processes and if the natural processes have the upper hand then most of what we plan in the normal course of policy would not be very effective okay in which case let me follow up with Richard on that one in 2009 Richard you wrote that quote there has been no statistically significant net global warming for the last fourteen years so that's going back to the year 1995 let me ask you then whether NASA's map which we just saw in that video with many other regions of the world turning red catching a fever I think was the way NASA put it is that a falsification of things I think it is in some ways I mean the use of language is first of all a little bit strange the problem is as always detecting the signal in a noisy environment I mean you know I don't know if Hadi has done this but if you take all the temperature anomalies from all the stations used it forms a dense cloud with a width of about four degrees centigrade when you average it using the same scale you see almost nothing then you blow the scale up a factor of 10 and you start obsessing on the changes but you know Hadi was mentioning aerosols and we could come back to that because that's a huge unknown and it's a standard fudge factor in the models the truth is the warming we've seen if it were all due to greenhouse emissions would suggest that we don't have a problem the increase has been what you'd expect if you had no amplification the problems that are being projected have two peculiarities with them one they require models that respond very strongly to increasing greenhouse gases and more strongly than we've seen so they use the aerosols in each model to cancel whatever they need to match the data but on top of that this global mean temperature anomaly is a residue of much larger things going on and it's rather unique in science and I think kind of fallacious to think of a residue as driving the things it's a residue of its it's a product of those things and so the whole discussion is a bit bizarre how do you want to come back on that yeah let me kind of expand on the comments about the models and our predictive capacity one of the biggest challenges we have in making climate modeling more successful is that we face a challenge of not knowing what the sensitivity of the climate system to radiative forcing is increases in greenhouse gases and also not knowing how fast they respond so what we need to do is to understand that this residue that Richard just spoke about is a representative of it could be the representative of a very sensitive model which reacts on a very long term or an insensitive model which is reacts almost instantaneously and unfortunately our ability to discern which one of those two worlds were in is a beyond current science the challenge lies in knowing that if we are to become completely confident in the nature of the sensitivity of the model and the time scale on which the system is responding we need to wait a long time so at this point we get to the stage of should we be taking any precautionary measures with respect to that degree of ignorance or should we responding to these minutiae of the residual which Richard rightfully says is ridiculous so Richard how about that last question that hottie put any precautionary measures do you think we ought to be taking them right now yeah well I think you know there is a policy problem and I don't think hadi disagrees with this now the only policy you can design would be one designed to reduce the radiative forcing significantly I think it's fair to say that for instance Kyoto did not meet that criterion and if we look at what is needed to meet that criterion one is beginning to talk of things like sixty to eighty percent reductions in emissions and that's not going to happen so in terms of precautions I'm not sure we're in a position to even think about it very well so the question then is what does one really do and here I disagree with Hadi a little on on what the science can do it turns out and this is a little bit complicated to discuss but the length of time it takes the system to respond is itself a function of sensitivity sure but one of the beauties of models is whether they're right or wrong one can examine the models to see why they behave as they do we know that in order to produce dangerous scenarios they have to amplify greatly what co2 would do alone they do this via specific physical processes that can be identified in the models mainly with clouds and we are beginning to get good satellite data on these physical processes we can build mechanistic models to explain those processes and test whether the models are doing well at the moment it's it clear to me that the models are doing very poorly on that and so you know we're using them as a Ouija board we're saying if a model predicts something then it may be possible if it may be possible we should worry but in fact we are in a position to use the science to see if all the things predicted by models are in fact possible and that we should be devoting a great deal of effort to how D anything you want to quibble with there no not at all and I I mean the key here which is not often communicated to the public is that the Directorate of forcing from greenhouse gases is limited its how the system responds that amplifies this or attenuates it and if the system amplifies it then we're in for a very hot future if it attenuates it then the system works just like a thermostat in the house to try and maintain an equilibrium that it is maintained for some time there are there are issues here though if for example your air conditioning unit doesn't have the capacity to cool your home enough even the thermostat were where it to be functioning perfectly well would still not be able able to allow you to kind of escape a hot room the challenge here and Richard knows this very well is that there the ameliorating effects of the feedback systems themselves are not infinite and one needs to worry about the capacity of the system to ameliorate these signals according to the amount of perturbation the amount of greenhouse gases we put out and the next question which I'm sure that Richard wouldn't object to talking about is that it's not just climate change in a sense of warming that we have to worry about is the consequences of all the feedback mechanisms that may in fact keep that in check but change rainfall patterns and so on in terms of the client in terms of the weather people experience and also what's happening in oceans would respect to our certification all of these things are one of them the first part is a consequence of the feedback system that Richard was talking about the other part is undoubtedly linked to greenhouse gas emissions and and dramatically affecting the ecology of the ocean so it's not just one reason why we're thinking about reducing greenhouse gas emissions there are many of them one of which relies on slightly wonky models that Richard in my opinion correctly characterizes as being Ouija boards okay let me leave the modeling aside for a second and we I guess one of the key questions that we've got to get to the bottom of or try to anyway beyond is the world getting warmer or not the world is getting warmer the question is is the warming due to human-made co2 emissions and we've got a graph that unfortunately you too cannot see but our viewers will and I'll take you through it here here are co2 levels going back 400,000 years yes this is from NASA let's bring these figures up here they've been fluctuating between 180 to 300 parts of co2 per million for about 399,000 years steady for about a thousand years at 270 parts per million but then as this graph indicates it shoots right up they started going up during the 19th century and reached about 350 parts per million sometime in the 1970s and today our levels are at about 387 parts of co2 carbon dioxide per million and that looks like according to this graph the last 400,000 years the highest levels ever now one thing I do want to try to get to the bottom of with you too is whether you agree and Richard let's hear from you first on this whether you agree with the conventional wisdom which suggests that 350 parts per million is about as much as we can take as a planet and when you go beyond that we start getting into a real danger zone do you agree with that notion not at all I mean that that's a truly bizarre an arbitrary number you know when you're looking at the Earth's history you four hundred thousand years is nothing over the bulk of the Earth's history co2 has been much higher than it is at present most life evolved at much higher levels of co2 that's why plants are largely starved for co2 you know we're talking about levels of co2 and of course as Hadi has pointed out what we're concerned with with the greenhouse is the so called radiative forcing if we went from 300 to 600 parts per million volume that graph which incidentally was shown me earlier you know it's nice if your graph start at zero rather than at some level so it doesn't exaggerate what's going on but be that as it may that would represent a 2% or less than 2% fluctuation in the radiative budget now to put that into perspective the earth has had periods going back let's say two and a half billion years when solar brightness was twenty to thirty percent less than it is today and that addresses Hadi's point I mean how much can the earth stand well here you had gone the opposite direction 1015 times more than you're talking about if you went to 600 parts per million and as best we know the oceans didn't freeze and the climate was not terribly different from today's although very different world of course no life and the question is how is that possible and people have spent 30 years trying to account for it with greenhouse gases and failed on the other hand the earth at that time had an ocean had water at water vapor these are the main substances and clouds we've recently shown that it would be very easy to account for this so-called early faint Sun paradox provided that clouds are a negative feedback if they were a positive feedback I think it would be impossible to account for this paradox so I think we have ample evidence that the earth has dealt with far bigger changes than we're talking about now 1015 times bigger and dealt with it very successfully with the mechanisms that we still have today just before I get a response from hottie on that issue of 350 parts per million you've used a couple of scientific terms so far that our viewers I suspect understand one of them you talked about a fudge factor earlier I think we get that how about radiative forcing radiative forcing they need a bit of explanation go ahead okay all right it isn't a trivial term but it is the measure of what we mean when we speak about global warming in the active sense in English let us say causing warming normally let's say if the earth were in balance with space then the incoming Sneden coming sunlight would be balanced by outgoing heat radiation if you change co2 crudely you know instantaneously then you will cause an imbalance you will reduce the radiation from the earth to space and so you'll reduce its ability to cool in order to re-establish the radiation to space of course the system warms the initial imbalance is called radiative forcing and for instance the normal balance for the earth is you know something on the other end on the order of a few hundred watts in and out and this is giving you about a two percent perturbation in to about three and a half watts okay thank you for that I wonder if I could ask the control room once again just to get us back on track here to put up that graph that we had up a moment ago just a reminder we're trying to find out now from hottie whether he believes that that 350 parts per million of co2 in the air is that's the sort of conventional wisdom at what is acceptable for planet Earth and we've seen from this graph that over the last twenty five years we're now up to about three hundred eighty seven parts per million which for those who say global warming is upon us and it's because of us they say that's a dangerous level what do you say on that honey I would more or less echo what Richard was saying historically co2 levels have been much much higher and the beginning of life on Earth was at a time just like that so I would like to differentiate between arbitrary thresholds like 350 parts per million of co2 and kind of gross exaggerations of life on earth and its consequence for life on Earth I don't you know so let's let's get straight down to the brass tacks here I do not believe that 400 parts per million will be the end of life on Earth as we know it as Richard said we experience all sorts of climates and there's all sorts of ecosystems and all sorts of human communities in all sorts of climatic conditions and none of the things that I've seen in any of the predictions whether they paint the maps red or they paint them green mean that it's the end of the earth as we know it what I do want to come back to though is that the feedback systems that will hang on alladhi before you before you come up with feedback I want to nail down this parts-per-million thing here I'll go ahead so you're saying okay if we go to 400 parts per million it's not the end of life on Earth and Richard did point out earlier that you know many many many hundreds of thousands if not millions of years ago we were up over the 600's the question is if we got back to that could we adapt as a planet as a species could we adapt to life perpetually at say 600 parts per million of co2 in the atmosphere so I think the part that the part of the ecosystem that would have trouble are the oceans and they would have ecosystems within the oceans which are not familiar to the ones we have today but there will be life there so how do you define that updation hmm I guess life life as we know it today could we continue it at 600 parts per million social organization in 600 parts per million is that one question sure yes we would be have no trouble farming we have no trouble you know I mean even if you walk under the canopy in a forest you get to 600 parts per million right now okay but you're saying what happens what happens under the sea might not do so well well the problem is the acidification of the oceans because most of the creatures that make calcium carbonate right now base it on a chemistry that is more or less very close to the current acidic acidity of the oceans and as you raise the acidity it becomes very difficult to deposit the calcium carbonate but just as genetics allows a modification of even that system onto becoming more efficient at higher acidities I can't predict how far we are from being able to achieve that but in the long run I would be surprised if we can't because we did have calcium carbonate made in the oceans when the atmospheric concentration of co2 was 600 millions of years ago okay just in the interest of equal time Richard Lyndon if we went to say 600 parts per million of co2 in the atmosphere how would that affect life on Earth in your view very little frankly I mean you know we already as Hadi pointed out there are regions where people are living in that most auditoriums you've been in levels of co2 that high I mean there's there's a kind of demonization of this substance I mean it's I won't speak to acidification of the ocean I think that probably warrants looking into more and I'm no expert on it to be honest I suspect that's an issue which has been brought up as warming looks less tenable but you know I'll leave that to others but you know when you're speaking of co2 and warming you're speaking about this quantity radiative forcing I should point out that when the Intergovernmental Panel on Climate Change speaks of radiative forcing due to greenhouse gas increases they make it quite clear we're already at roughly 85 percent of the forcing one would expect from on the order of 600 parts per million yeah because you know there have been increases in methane and increases in and - Oh an ozone and so on so you could reasonably ask if the models that speak of disaster at 600 parts per million are true why haven't we seen it already howdy might respond that the response is slow and maybe but I don't think there's much evidence we've seen that the response time to thermal perturbations is that slow and that too is an indication of low sensitivity okay how di I promise you you could you could come back at that feedback issue but we sold a lot to cover do you want to do that or can I go on and talk about temperatures let's go about talk about something else and we can come back to that this time okay far that's thank you for that we've talked about how hot it is I want to get into now how hot it has been and to that end let's put up a temperature change graph we've got a graph that has shown the temperatures over the last two thousand years here and there are 11 different lines on this graph representing 11 separate studies and I want to ask you hottie what do the past records tell us about temperature change that help us deal with what we're dealing with today huh that we don't have a very good record is that the conclusion actually there are some things there that is not on your graph that I would like to draw attention to go ahead much of that graph before 1800s it doesn't use thermometers it uses evidence in nature that we associate with particular temperatures right so the ratio of oxygen isotopes is often used and so on and then we look at the ratio of these oxygen isotopes either in ice cores or we look at them in deposits in calcium or we look at tree rings all of those kinds of things allow us to kind of try and construct substitutes for a temperature record going back into the history long before the 1850s we've we know it's it's a brave effort but it has lots of errors on it and it's also very localized so just for an example if you look at the the construct reconstructed temperatures of the North Atlantic region ten thousand years ago and before that you find the highly fluctuating climate highly fluctuating you know there are almost as much as ten degrees on a decadal basis if that is an indication of climates of the past in a given location one of the things you could be sure of is we could never have had agriculture because if temperature changes that much we would never have developed agriculture we would have never developed the the civilization that depends on agriculture so the readings must be wrong I'm not suggesting the region's are wrong I'm saying the readings are very local and and if the readings are right one of the questions that I would like to have answered and there are no answers to it is why have we had such an equanimity such a wonderful kind of Goldilocks period of stable climates for ten thousand years globally Richard you want to come back on that yeah I mean I don't disagree proxy data has profound limitations and the graph you're showing although it shows quote a lot of quote independent studies they're not independent they generally used the same proxies very few of them actually use different proxies so they all have different ways of analyzing it but it's it's a dubious business and and you know the National Academy in the u.s. looking at some such studies concluded the methods probably cannot be used going back further than 400 years and just tell me what you mean by prognosis that proxies are what Hadi mentioned when you don't have thermometers and you use tree rings and isotopes and cores and so on there's a preference for tree rings because they have high time resolution some of the cores have rather coarse time resolution and so you miss a lot of the higher frequency or shorter time scale variability as I mentioned before though even with thermometers if you look at North America which isn't that local you find that the variability the anomalies are much much bigger than they are for the global temperature average global anomaly average and so when you have local measures you inevitably see bigger variability if you look at Toronto or Boston or anyplace and look at the high and low for each day around this time of year they'll be separated by 4 or 5 degrees 10 degrees even and that's huge compared to what the global mean will be doing so you know one has to be careful with these records you only have a few of them it's you know we're having trouble getting this level of temperature change out of thousands of thermometers they have enough problems the notion that you can take two dozen tree rings and do the same thing given that tree rings depend on the growing season they depend on moisture they depend a lot of things other than temperature is being perhaps overly optimistic so let me just understand then and how do y'all go to you on this one if if you are a scientist today who's trying to convince the public that climate change is a real thing and it's based on activities of humans on this planet and you're using the studies indicating temperature changes over the past 2,000 years such as we've just demonstrated them then that part of the case you are making is built on a relatively shaky foundation is that what I hear both of you saying yes hmm is that is that widely accepted in the IPCC world if they actually think it is so we have consensus on this one here I think that those who use these records which are proxy records recognize their limitations and the public communication has been used has been using them without perhaps echoing the limitations that the scientists are aware oh okay our first chapter tonight was how hot it is we've just finished how hot it's been and of course we're coming in for the home stretch now on how hot it's going to get one of the major areas of disagreement among people today is on solar activity as a potential source of warming we started off the program playing a clip from that NASA video I want to come back to that now play a clip and then we'll come back and talk roll tape please NASA satellites measure the sun's energy which fluctuates due to a 10 to 12 year cycle could increased solar activity be causing global warming satellite evidence shows us that the solar cycle has only a slight impact on our planets temperatures in fact even though the last few years have been some of the warmest on record the Sun has been in a deep lull in activity that means slightly less solar energies been reaching earth and when the solar cycle ramps up again scientists expect temperatures will rise even a little more scientists hoti expect temperatures will rise even more so here's the question is the activity of solar rays predictable predictable you mean can we predict the activity of the Sun in its 13 year or so cycle precisely ah somewhat but I actually think that the that there was an oversimplification of the science right there in the clip you played okay help us then so how are you measuring the energy output from the Sun and how do you measure the highest energy rays from the Sun that could be producing clouds high up in the atmosphere so the notion that if we have more energy coming out of the Sun that it would be part of the same spectrum in fact you know when we have dark spots spectrum changes and that does not affect cloud formation in the upper atmosphere which was them which was exactly what Richard mentioned as an example of how it was that the earth remained relatively warm even though solar activity was lower measured those are the kinds of oversimplifications I find frustrating in the public messaging of the clip you played so if we were going to be more nuanced about it which might be harder to explain but perhaps more accurate what would you want to say on that I would like to understand how solar activity affects the feedback systems that you know Richard and optimistic people about global forum global forcing would invoke as keeping the earth relatively cool Richard your turn on that yeah I have a couple of objections to it I know big fan of solar forcing mean may exist of course ultimately the Sun is the source of energy that isn't the question the variability as far as we've measured it is pretty small but I have an objection to the whole notion that you can assign to climate a single number the global mean temperature anomaly and assume it is forced by another single number either greenhouse gas or solar activity the system is much more complex than that and you know the major climate that was indicated on your graph for 400,000 years was the ice ages and we're pretty confident at this point that those ice ages were driven by variations in the Earth's orbit and what those did was change the mean incident radiation almost not at all but they changed the distribution of it immensely and it was the change in distribution that led to the ice ages and the interglacials between them and so to take a single number and try and explain that would have been impossible and yet we've been reduced to this extraordinarily naive position that climate is one number global mean temperature anomaly and forcing is another number and that's just not how the system operates let me get haughty to react to that and in doing so I'm actually going to read a quote of Richard's that that we have here on a graphic the quote goes like this the notion that complex climate catastrophes are simply a matter of the response to a single forcing meaning a single impact co2 or solar forcing for that matter represents a gigantic step backward in the science of climate many disasters associated with warming are simply normal occurrences whose existence is falsely claimed to be evidence of warming and all these examples involve phenomena that are dependent on the confluence of many factors in other words Hoddy you can't isolate one and say global warming happens because of that so what are some of the examples of things or events wrongly associated in your view with the rise of co2 first of all let me say that I completely agree with Richard statement on the in that sense and and one of the frustrations I've had is the attribution of almost any extreme event that occurs to climate change and a great example of it would be from around British Columbia where I live where people would say you know the last big forest fire is because of climate change well there are two reasons why that kind of a statement is clearly false one is that we've completely changed the way we manage forests and how much forest material is available for full for fires and the other reason is that we've got long histories of fires due to natural events here anyway and the third reason I think I'm now beyond the number of two that I've given you is that we have a lot of human beings living very close to forests and they throw matches and cigarette ends and so on all over the place so more fires can be caused you know I I find it's just oversimplification to say that a drought here is because of climate change or a fire there is because of climate change or that mounts see more having trouble hosting the Olympics is because of climate change we know that whenever there is an El Nino event they have trouble with snow we couldn't have predicted it that we're going to have an El Nino event at the time of which Vancouver won the bid but the fact that it occurred is not related to climate change but conversely Richard there I guess scientists on the other side who see the facts that you all see but come to a different conclusion from you and say the rest of the world is adamant to suggest that these things don't mean climate change is happening but they see disappearing snow Peaks melting polar caps an increasing acidification of the ocean and they say that is evidence that the co2 levels are rising and that we're responsible for it how do you want to react to that yeah yeah I think the there's a logical fallacy in that I mean what you have here if you looked in detail is you have perhaps 11 to 20 large scale models and they run these models with increased co2 and some of the models will predict something happens to Arctic sea ice some predict something else and so we developed the vocabulary that some models say that something will happen to artic sea ice if you double co2 but we know that sea ice depends on many things it depends primarily on wind patterns during summer and so now you see sea ice change is that really evidence of warming well no because there are many confounding factors that go into it then it's I mentioned and something you quoted for me something called the prosecutors fallacy in simple-minded terms it says is if a shot be a will have gunpowder on his hands that's certain on the other hand if si has gunpowder on his hands and he lives a thousand miles away it's much less certain that he killed B and we're making that confusion every day in our attribution of weather and events to climate change okay I know you were both thoroughly enamored with the first clip we played from NASA I know you were both less enamored in the second clip we played from NASA let me beg your indulgence one more time because we want to look into two other issues now that scientists have used to establish models of future warming and we can talk about whether or not how legitimate those are first of all on clouds second of all on water vapors let's check out these clips roll tape please clouds also reflect a lot of sunlight as our planet warms more water evaporates potentially creating more clouds more cloud cover increases the Earth's brightness possibly helping to cool the planet but clouds and the small particles called aerosols that help them form our climate wild cards many current climate models predict some cooling due to increase cloud cover will it be enough to significantly slow warming scientists are using NASA data to look for the answer further complicating the issue is that water vapor is actually the world's most abundant greenhouse gas that's right the same molecules that might cruel the planet in cloud form actually warm it when they're in the form of a gas they help create a blanket around the earth catching heat radiating from the planet's surface and trapping it within the atmosphere as the planet warms more water evaporates from the ocean creating more of this heat-trapping greenhouse gas humans can't directly control the amount of water vapor in the air but we can have a much greater impact on other major greenhouse gases carbon dioxide is the second most prevalent greenhouse gas and it's our biggest contribution to global warming ok Richard to you first this is where the science gets both confusing and frustrating because as that clip suggested the same molecules can have two different outcomes and you have written the question remains as to whether water vapor and clouds have positive or negative feedbacks so please go into that a bit and explain if you would yeah it's a lot to explain in a few minutes but you know the clip that you presented is misleading even at the level it was operating for example it says clouds reflect light actually that's true but clouds are also fantastically important greenhouse substances and when the clouds are high level thin cirrus which are ubiquitous they're more effective even than water vapor is a greenhouse substance so clouds can they can cool water vapor is important where you don't have clouds but then the area covered by clouds keeps changing so the whole thing is is pretty confusing and this is where I think satellite data will come into its own it's something that can give us a kind of synoptic view of these things clouds even water vapor and it also allows us to measure the radiation directly that's being reflected by the earth being emitted by the earth and so I have a lot of hope that that sort of data can pin down these things without waiting decades the real problem is and something that your NASA clips reveal there's almost a commitment to warming as an issue that has built up so much momentum that even when you talk about taking data you don't talk about testing models which is what you should do you use vocabulary like validating models and I think that's getting off on the wrong foot Adi can I get your view on that video oh yes I am first of all you have to realize that Richard is one of the world's experts in this and that I fully endorse his comments about the complexity of understanding clouds and I would add further that the amount of error that aerosols can dramatically change the properties of clouds and we are creating enormous mountains of aerosols through industrial activity for example in China right now which is dramatically affecting all these processes and our own ability to understand them is rather limited and our commitment to speaking with alarm about the process is significant enough to influence instructions to authors of the IPCC in which case and here's I guess the $64,000 question are we in a position to predict the future of global warming honey go ahead I don't like the notion of doing this as a single number single process single driver challenge and I have been challenging that as part of the part of the group who contributed to the IPCC in the 90s and the early to century there are multiple factors I think we need to be careful about what's going on and act according to the knowledge we have and hopefully learn more about where intervention can be more effective in which case with just a few minutes left to go in our discussion here let me ask you this Richard to you first is there a piece of evidence that would make you doubt the position you currently take on climate change good question oh yeah sure there is I mean you know there are measurements we're analyzing now I mentioned some others but these are particularly important the feedback mechanisms that we've been talking about which amplify or perhaps restrain the effect of co2 operate on very short timescales days even they involve cloud physics this is not long-term physics we have lots of fluctuations in global mean temperature that are occurring on timescales of weeks months years but even shorter periods are what we're interested in and if we look at space we we know how much cooling the earth should produce if you don't have feedbacks and if we see that there is more cooling than we expect and we know there are negative feedbacks and if there is much less we know there are positive feedback and if I were to see from that measurement that every time the temperature rises or Falls the radiation observed from space changes in a manner consistent with a positive feedback I would certainly reconsider my position so far we found the opposite well this is important because so far the discussion you know widely held seems to be among climate change believers and climate change skeptics which means positions are entrenched and not necessarily changeable based on emerging information but you have just told us that if different information were to emerge you would follow it so that's that's interesting to know Hoddy how about you about a minute and a half to go here what could change your position no I mean my position is very similar to Richards and the only thing we really haven't discussed yet is whether the feedback mechanisms that are at play if they happen to be ameliorating global average temperature anomalies happen to have impacts of their own that we ought to worry about for example if the clouds are affecting photosynthesis rates or agriculture or precipitation patterns these in themselves may lead to the global average temperature having very little movement in it but dramatically different climates for the locations in which the feedback systems are operating that in itself is an impact and we need to make decisions based on the desirability or lack thereof of those feedback mechanisms even when they're effective in leaving us with a pleasant and relatively stable global average temperature Hoddy in our last 20 seconds here you two sounds so reasonable and rational in having this debate tonight what percentage of scientists around the world share your rational approach to this and what percentage are ideologues you're asking me yeah I think too many of them are entrenched in the and the message well I didn't hear any of that tonight which was a nice pleasant change I want to thank both of you for joining us on TV Oh tonight Richard Lindsay professor of atmospheric science at MIT in Massachusetts of course in Paris tonight Hadid alotta body Canada Research Chair professor of applied math and global change at UBC in Vancouver congratulations howdy incidentally on fantastic Olympic Games which I don't know if you had anything to do with but we're all still talking about it in the rest of the country thanks so much to both of you thank you

Channel: The Agenda with Steve Paikin

Views: 291,566

Rating: 4.584959 out of 5

Keywords: TVO, TVOntario, Ontario, Canada, Agenda, Steve, Paikin, current, affairs, analysis, debate, climate, change, environment, global, warming, al, gore, doomsday

Id: gJwayalLpYY

Length: 52min 15sec (3135 seconds)

Published: Wed Mar 10 2010

Reddit Comments

[u/qp0n]

I cannot help but be amazed at this level of civil discourse was even permitted on the subject of global warming. It is unheard of when compared to the lockdown on climate science that exists today.

Today's 'conversation' about climate change seems far more reflective of the blatantly manipulative, biased, leading, and insinuating tone of this mediator in the video, instead of these actual scientists (who seemingly were invited to disagree with each other but couldn't help but agree).

In other words, in the last five years we have since stopped listening to the actual fucking scientists and just went with what fear-mongers have long been desperate to hear.