itself also serves in the department of civil and environmental engineering he's an expert on the relationship between clouds and climate a major focus of climate research dr said so has also been involved in a major atmosphere missions for nasa and he's received numerous rewards and i'd like to say also he is responsible for giving us the space for this lecture series and we thank him very much in this talk tonight dr tso will address the issue of climate change but with an emphasis on geo engineering specifically on the current advocacy for geo engineering as a slut solution for climate change and the inattention to the side effects of geo engineering it's now very important for climate scientists to inform the public about the hard reality of climate change and the inherent complications of geo engineering and we appreciate dr  commitment to provide clear information for the general public he is by the way a wonderful translator of technical information for non experts we are very honored to welcome d atmospheres and in speaking recently we realize that this topic of geo engineering has become a big story in the news recently that there's a lot of misconceptions out there and so what i'm really hoping to do tonight is talk through the science behind geo engineering and ultimately at the end of the night i hope that you guys can make your own decision about being proponents of this perhaps drawing a line in the sand that you don't think it's a good idea or which aspects of it you think are reasonable which you don't think are reasonable so i really hope that we can educate ourselves over the course of the evening to do that so the idea behind geo engineering in a general sense is manipulating something about our planet we don't like and so  to start out with the topic of geo engineering in contemporary news that really has to do with the climate of our planet and so to to get started tonight i'd just like to show a couple figures and talk through the basics of climate science to give you guys an understanding of what it is that we don't like about our planet right now and how we might think about changing that so this is you know the state of the climate it's a bit like you know the state of the state or the state of the and you can see by the heat bar on this this expresses when in a certain area of the world the temperature is higher or lower than it was in the year one thousand nine hundred and i think it's pretty obvious that you can see across the vast majority of the surface of the planet that the temperature is higher in a globally average sense so the temperature everywhere averaged over the year the temperature of the planet's about point seven five degrees see warmer over land alone it's about twice that one point five degrees warmer  and that's relative to eight hundred eighty this is largely attributed to c o two an increase in a greenhouse gas that we have in the climate in the climate system it's past four hundred parts per million a couple years ago so we can wave by to four hundred parts per million it is unlikely in our lifetime that we'll probably see under four hundred parts per million before the industrial revolution started we have very good evidence to show that it was about two hundred eighty parts per million and that's typically where it is during the recent interstitial periods the periods between ice ages so as a result of that we can think about what the average temperature of the planet is on a yearly basis so these are the warmest years on record  number one is twenty sixteen twenty fifteen twenty fourteen they're going to notice a trend here there's a lot of to thousands on there this is all the way back records to the eighteen eighties when we first had accurate for ma matters on the planet you don't see many eighteen hundreds on there early one thousand nine hundred john they're really all within the lifetime of the folks in the room here and so one of the things that i'm find of saying is that when we talk about our children seeing a different climate than the one we're in hello the climate now is different than the climate that we all grew up in the years that the first couple decades of my life are not represented on that figure they're only the last couple decades or in the twenty warmest years just last month we got the final data for twenty seventeen and that would check in at number two on this figure so i need to update this shortly if we use things like temperature proxies tree rings that type of data we can go back further in time and it's very very likely that the temperature now is greater than it has been in thousands of years so if it was just c o two we would probably have a very good handle on the climate now and projecting it into the future but we're not quite sure yet and one of the reasons  is something that i'm going to try to show here so this is a real image of the earth or more correctly it's a real mosaic of images from the earth this is a poster i had up in my wall when i was a kid from the japanese space agency and of course what's missing from this if you were really looking at the earth from  space thank you so it doesn't really look like that if you take a single image and you don't sort of cherry pick images and them together that's what the earth should look like at any one time and so why do i mention this in the aspect of climate will those clouds are very very reflective so they're going to be sending some radiation back to space about thirty percent of all of the photons that get to the earth from the sun are actually reflected back into space by ice by other reflectivity by clouds and by particles and so at the same time as we've been increasing greenhouse gases and causing the warming of the planet we've also been doing things that are causing the cooling of the planet sort of offsetting some of that warming so this is singapore from a few years ago this is a pall of smoke over over singapore and so what you can see here is that some of those photons we just talked about that are coming in from the sun this is otherwise should be a bright blue clear day but you see this hazy image that's been taken and that's because some of these photons are actually striking those particles that are in the atmosphere and being reflected back into space this is what we as scientists call the direct effect of particles their direct impact on radiation you can say well particles are natural showing this image these are not natural particles these are fires that were set to clear land specifically peat bogs so that they could be used for agricultural purposes so these are fires that were set by humans to clear land for land use changes and these are particles that are participating in the rate of balance that are there only because of us so that's the direct effect with these particles have so if we acknowledge that we as humans are changing particles we're changing climate in a cooling sense we're changing the  reflectivity of our planet those particles are also important because they act as the seeds on which droplets and ice crystals form so if we change particles we climate directly but we also change cloud cover and we call this indirectly affecting climate we create more clouds or we change the reflectivity of the clouds that are there this is one example of how that could happen on the left hand side this is sort of a pre industrial atmosphere only if you particles we as humans haven't started putting particles there there's some water vapor the particles that are there pick up that water vapor and form a club on the right we have that same cloud post industrial activities many more particles the same amount of water that water spread out over a lot more particles so the particles are smaller they don't gravitationally settle they don't precipitate as fast and those particles reflect more radiation it's a brighter a whiter cloud so more reflectivity so these things contribute to the enhanced of the planet and thanks to von we had a chance to do some demonstrations for a few videos and so that's the youtube link on here that will be available on the slide so take a look at it in another plug for science for the public so we as climate scientists can add all of these things together we can take the greenhouse gas warming and then we're going to put an error bar for how certain we are about that we can take the other anthropogenic forcings these particles the clouds that are being created we can put an air bar in that by the way you'll notice that that error bar is larger than the one in the greenhouse gases we can add those together and get a combined forcing we can try to equate that with the observed warming of the planet you'll notice that the two are are pretty similar we're doing a pretty good job of understanding climate but there's still some errors if it's towards the low end of that error bar or the set of areas we might project climate in the future of a few decades into the future incorrectly we might say that the temperature is going to be lower than it actually is that's towards the high and we could have the opposite problem we could under predict the amount of change so understanding that in shrinking those error bars is really critical to projecting climate into the future to other things that will circle back to at the very end or that natural forcings and natural internal variability think of this is being the heat of the earth changing over a long period of time the orbital mechanics of the system changing over the period of the the decades or century that we're talking about changing in affecting the climate those things are perturbations they can change the climate of the planet but they can't do it over a period of decades or a century and so that's why you don't see much there's some uncertainty on that but there's not a measured effect it can't rival what we as humans have done in terms of greenhouse gases and in terms of particles so that's a very brief introduction with our first ten minutes or so just to get the stage set for the state of our climates are right now so now we're into this idea of geo engineering and to explain geo engineering we actually have to go back a little bit earlier to a term that you guys may have heard especially fiction which is terra forming so terror forming is this idea that we can change something about a planet to make it more earth like so the classic case of terra forming that we as humans think about is mars so this is supposed to be mars in the present day we somehow find a way to warm up the martian climate system we start to melt a lot of the water that's there we melt the polar caps you end up with oceans on mars for example so that's terror for me this actually goes back to a novel called collision orbit from the one nine hundred forty s one of these little serial  novels from an author named jack williamson but if you really think about it we can go back yet further in science fiction so if anybody has ever read war of the worlds hopefully you didn't see the really terrible movie with tom cruise in it but the original h g wells book is actually quite good and the concept here is that the martians are trying to mars form the earth right there they're coming here and they want to make it more martian so that they can live their same ideas terra forming but going in a slightly different direction so you can think about this is why restrict yourselves to process something that you want to change about the system largely this means global warming it doesn't need to it is a more general term than that so you can think about any aspect of the climate system and want to change but because of where we're at in the modern day this really has taken on the meaning of changing global warming trying to reduce that temperature we talked about earlier it's generally attributed to a scientist christian who i'll mention a few moments but there's a lot of earlier works and i'll try to get to the history behind this  in a few moments so a little bit over ten years ago wrote what's now become a rather famous paper the selby doa handsome by stratospheric sulphur injections a country contribution to resolve a policy dilemma so this caught a lot of attention because paul christian is a famous scientist he won a nobel prize in chemistry for figuring out the basics of ozone depletion because of c f c s industrial chemicals things that we put into the atmosphere so he wrote this paper in two thousand and six and he starts up by saying by far the preferred way to resolve policymakers to lumber is to lower the emission of greenhouse gases meaning the obvious solution to global warming is to reduce c o two he then goes on to say that although by far not the best solution that there's this proposal that we might do something to the atmosphere geo engineered the atmosphere so that we got rid of this temperature effect his proposal specifically is to put sulfate aerosol into the upper levels of the atmosphere into the stratosphere a very stable layer of the atmosphere where things like particles will hang around for about a year's time he refers to some earlier work which we'll talk about in a few moments and then he concludes with finally i repeat the very best would be if a mission greenhouse gases could be reduced so that this wasn't necessary i often joke with my students that if they did this on a term paper i would fail them if your thesis statement is that you think that the best idea is to get rid of greenhouse gases and then the body of your paper talks about an alternate solution that you don't think is as good of an idea and then your conclusions are to say that your original thesis statement was the best idea that's not a good paper so i guess if you're a nobel prize winner you can get away with this it has gained a lot of attention and so this idea came out which really revisited a lot of earlier papers paul kurtz who was not the one to get this started you can think about works going back into the one nine hundred seventy s where the same idea was proposed so i want to be very clear about this this idea of injecting particles is what we just talked about as something that we inadvertently did to our climate system which is offset some amount of global warming so there's a warming from greenhouse gases there's a smaller cooling because of particles in changes in clouds and so the really the idea being put forth here is if a little bit is good why don't we do more of it to completely interact or cancel out that large of us want to give you a little bit of perspective about how long ago we started talking about manipulating the temperature of our planet this is a report restore the quality of our environment the environmental pollution panel president's science advisory committee at the bottom of the page you see there one hundred sixty five this was the johnson administration this is a quote about understanding climate changes may be produced by increasing c o two but that you could offset this by counter very countervailing climatic changes such as raising the planet so it kind of cracks me up when you watch the nightly news and you hear about climate change skeptics and climate change deniers when in the one nine hundred sixty s the white house was writing reports about the possibility of changing the climate because of c o two as well as trying to offset that by something that we did to the says the climate system it turns out by raising a bit of they didn't mean adding particles to the environment they wanted to change the reflectivity of the planet by throwing ping pong balls into the ocean ping pong balls being rather reflective ocean water being rather dark i'm not making this up so the idea was really to produce these very reflective very white ping pong balls spread them over a large surface of the ocean change the reflectivity of the planet and cool the planet as a result now that we're talking about plastic waste in the environment and in the ocean i wonder how folks would feel about this it turns out that that report wasn't even the first time this kind of thing was proposed the basics of climate science actually date back into the lady eight hundred by  jonathan tindall john tyndall and eunice foote eunice foote from cambridge massachusetts arrhenius who followed them up who really did the basics of understanding that carbon dioxide would warm the climate if you put more of it into the climate system and so people often go wow how much foresight was there these people were thinking about you know the industrial revolution which was barely one hundred years old at this time and that the planet might get too warm that's not what they were talking about this was from sweden he didn't like the cold winters in sweden he wanted to increase the emission of c o two to warm up the climate system he wanted to geo engineer or warmer climate in the eight hundred eighty s so that the planet got more comfortable for him he wrote a book in  eight on this topic it doesn't appear to me that he really thought about what was going to happen in southern europe or other places that were already warm he was very much a homer and in that sense it was really just caring about scandinavia nonetheless this fits the bill of what geo engineer ok so so let's talk about what it is that's being discussed by scientists some scientists in the media recently so these are geo engineering proposals there's a whole host of things on here this is an article by new scientist which lays them out graphically two out and return the climate system back to where it was before carbon sequestration you can think of this in an in a number of different ways of show a few examples later but it's removing that c o two taking that four hundred parts per million down to two eighty parts per million or a number that we as a society decide that we want to try to hit the other geo engineering concept is to change the  it's often called solar radiation management or s r m this is a rebranded name for geo engineering but i'll try to tell you in a few moments why i think that the correct term for this is modification so again the idea behind this as paul kurtz and talked about is to add reflective particles to the atmosphere or change the cloud cover of the planet more clouds more reflective particles the reason that i like the idea of modification and this is backed up by a recent report report from the national academy of sciences is that geo engineering at its heart is not the correct term to use when i say engineering to you think about engineering a system doing something that you want a likely outcome to the system by rebranding it is solar radiation management the folks that are proponents of this use the term management that has the same implication you manage a system for an end result that you know that you're going to get or that you have a high probability of getting beat a modification is really the correct term because we don't really know right now what the result is going to be there's too much speculation i'll try to show that you so we can talk about wanting to modify albeit oh but not being certain of the consequences of that so i mention that there is this recent report by the national academy of sciences so this is a nonpartisan commission so as a group in the united states or really internationally as congress anybody can charge the national academies with the goal of this was something set up by president lincoln in the eighteen hundreds as being sort of a nonpartisan way that we can think of of solving or addressing different topics so they were they were asked about twenty thirteen the report came out in two thousand and fifteen i believe to tackle this idea of geo engineering the report writers instead of writing one report on geoengineering wrote two reports one was carbon carbon dioxide removal the other one on reflecting sunlight modification i like to joke with my students about this is well if i ask students to produce a term paper for me i have yet to have a student that gives me two term papers but that's what these folks did for the national academies well you have to ask yourself well why would they sign on to do that why would they write were two reports instead of one of the basics behind this so that they felt that these two things that we just talked about were so completely different that there was no way that they could be encompassed in the same report removing the carbon dioxide and returning back down a climate ramp that you've been on before with the certainty implied by that was completely different than perturbing the atmosphere in a new way when you're already at a higher carbon state by changing the beat of the planet and so for that reason they said we have to write two reports so this is part of the synopsis of this i'm breaking the cardinal rule here which is i'm not supposed to put so much text on the board that you're not going to pay attention to me  but look at where the blue lines are and here what they're talking about is carbon dioxide removal strategies generally being low risk and almost certain benefit but that the cost and the readiness level are not there they're calling for more work on this and they're saying that you know for the amount of temperature change that you would get the return to normalcy that it would cost quite a bit sort of dollars per ton of carbon cancelled out whereas l b don't modification comes at an unknown environmental price it might have a rapid effect we're not quite sure what that effect is the magnitude of that effect but it would come in an unknown price moreover not in here they're talking about how it would be a very cheap solution and i'll show you more of that later so it becomes very you might be able to change you might be able to change something very rapidly at a low cost much lower than carbon sequestration or car so just a few words on carbon sequestration this is the idea that you know either just directly from the atmosphere you capture that c o two something that's called direct carbon capture very energetically unfavorable much more likely much more probable that what you could actually do is grab the carbon out of the stack that's producing it you know you burn the fossil fuels you grab that carbon when it's concentrated coming out of the stack you sequester it back in the air the other thing is you can let biology do this for you you can grow b even choose to take some energy out of it but you find a way to take that carbon down to its most basic form perhaps like a charcoal and bury it or combust it all the way to c o two and then capture that c o two again at the stack and sequester it all of these things being worked on right now so this is not science fiction these are all things that are being deployed to some level of readiness right now but of course more can be done be done modification on the other hand is a difference the idea of basically works from the energy balance of the planet and as i mentioned before incoming solar radiation i solar on here normally makes it to the surface minus about thirty percent which we call the of the planet so that seventy percent that makes it to the surface warms the planet some of that energy is reradiated back into the end atmosphere captured by greenhouse gases and then like a blanket reradiated to the planet more greenhouse gases thicker blanket warmer temperature if you change that i'll be too though you let less energy into the surface of the planet so maybe as you're increasing that blanket you try to increase that sun shade at the same time so right now the go on the y axis there is thirty percent  about the same is what deserts are right now it's actually the integral of all the different surfaces on the planet oceans are quite dark snowing clouds are quite bright and so something like the balance is thirty percent the idea is can we change that c acid which turned into particles those particles then drop the global temperature by about half a degree c for about a year and a half or so there's a folding time is these particle slowly fall out so it's fairly stable on average they're going to live about a year some particles are going to get lucky and hang around longer so you're going to see most of the effects gone after about a year but some transit effect still there about three years later these are those particles spreading out so pinatubo is in the philippines you can see it very rapidly making it around the planet in the stratosphere at those latitudes and then sort of slowly spreading pole words over the course of the next several months creating this global effect and as i mentioned we saw this change the temperature of the planet so the observations on here and black model results are in red uncertainty in those measurements but what you can see is that the last three major volcanic eruptions  and all ended up putting material into the stratosphere that material reflected sunlight it dropped the temperature the particles fell out and then we returned back to sort of the normal temperature of the planet that's also superimposed on a rise that's going on there and that's global warming that's anthropogenic warming of the planet some folks might actually remember that we had mount saint helens go off in northwest mount st helens as large of an explosion as large of an eruption as we think of it being was not powerful enough to put a lot of the sulphuric acid material into the stratosphere and so it didn't have a large temperature effect it was mostly a local regional effect instead so this is where the direct effect method takes off modification  in the next year and the next year and the next year to make up for this this is actually a design that's been proposed basically these are we that are also balloons that are holding essentially a large garden hose up into the stratospher holes or poked in it and your spring out so acid into the stratosphere to create those particles so you can ask yourself what's the difference from a volcano well the immediate one is that this analogy that geo engineering is like a volcano is absolutely wrong and the reason is volcanoes are transients those are transients signals in the atmosphere they're gone in a couple of years geo engineering at its heart is talking about doing this and then continuing to do it and i think anybody knows that a step function is different than a transit so we don't have an example of what happens to the atmosphere from a perturbation like this there are no volcanoes that leave that particular loading that high so it's not an analogy initial efforts were cut off  e this was tried in the u k they propose doing experiments like this to see what of effect it was going to have that got cut off because of treaty violations the idea that you can't just unilaterally spray stuff into the atmosphere and see the effect it has it dates back to post vietnam when things like agent orange were being used and countries ratified treaties to not do this type of work so there's real reasons that this were cut off so that if anything like this was attempted in the future we would have to see how that was going to play out how we were going to do that or violate treaties that are in place briefly mention that there's ideas of changing cloud cover over the surface of the planet as well not changing the stratosphere but just in hansing clouds there are some natural cases these are ship these are ships off of the coast of france and spain that are not producing smoke but they're producing sulfur sulfur dioxide as a consequence of fossil fuel burning particles are being formed there's also diesel particles or or black carbon particles in some cases coming out and there's clouds being formed behind them so folks have actually attempted to do this attempted to make clouds in the same way it only works about one in every ten times and people haven't quite figured out when that occurs why ten percent of the time it works and ninety percent of the time it doesn't work so the idea here if you tried to manipulate clouds that you would have a lot of sort of false positives you would be attempting to do something that wouldn't actually work out that hasn't happened hasn't stopped people from imagining what ships to do this might look like so that's what's shown in the lower right corner this is a geo engineering ship it's going to steam around the world in some way it's going to suck up seawater it's going to break it into particles and object it into the atmosphere and clouds are going to form presumably on those particles apparently were only one in every ten times it's not clear how much energy it would take to the ships around to aerosolize that seawater and injected into the atmosphere but you do end up with clouds as a result of so elon roebuck who also wrote that earlier paper on mount pinatubo wrote a paper in two thousand and eight now about ten years old talking about the risks as well  as the rewards of this idea of modifying the of the planet and i think he did a really nice job of this and so you know you do get certain rewards and this is the type of thing that you are going to have to judge if these are important enough if you put particles in the stratosphere there is a good probability that you're going to reduce the temperature of the planet if you increase cloud cover if you can make clouds effectively you're going to reduce the temperature of the planet so that's number one that's probably going to the consequence of revers ice loss and sea level rise so you're probably going to shut those two things down because they're so inherently tied to temperature there are insufficient studies to say how plants grow under non direct sunlight so if you make sunlight more diffuse or you increase cloud cover there are studies that show plants don't grow as well there's not a lot of studies but there are some studies that say they don't grow as well you should become a little wary at this point i do because number five on the list of rewards is nice sunsets i don't know if anybody knows this famous picture this is the scream by munch so munch painted  this after their option of a volcano in the late eighteen hundreds and as those particles made their way around the world they defused a lot of radiation so what did they do they changed the way that sunsets look so if you look at all the variations of the scream i'm not sure how many of the there actually were that were made they all have this crazy looking background going on i guess sunsets are a nice reward the person in the scream doesn't seem to think so i guess everybody reacts to sunsets colored sunsets differently but nonetheless allan put that is number five he also mentioned that perhaps if you change clouds this would lead us to be able to control precipitation better that if we know how clouds work that this might lead us to control and try to talk about that in a few moments because this is actually something that falls into the risks as well so what are the risks well if you put if you change the temperature of the planet or you change especially if you change clouds you can create regional droughts so that's the other side of precipitation control if you change temperature but you allow carbon to be emitted carbon dioxide is going to be taken up by seawater which is ocean acidification so ocean acidification is not a consequence of geo engineering but it proceeds unabated because you have only tackled temperature you have not tackled the carbon problem so your place on those particles diffuse radiation effects on plants just like there are studies that say plant productivity would go down there's a few other studies that say plant productivity goes up there probably are some plants that grow better with diffuse radiation things that grow under can es there are definitely plants that grow better with direct beam sunlight so there's a bit of a mixed bag here i won't go through all of these but you can read through all of them the acid if you put it into the atmosphere has to go somewhere you can change how the cloud cover in an uncertain way number eight is something we'll talk about lower power margins on solar so if you go to diffuse beam as opposed to direct beam you change the power margins on photovoltaic and concentrated solar one of the tick technologies that you're looking at to take up the load from fossil fuels becomes less powerful less likely to work at least work as well there's a whole host of other things on there donald rumsfeld ism at the end at the end one of the real bugaboos of this is the unknown  unknowns i mean so we can list a whole ton of things and we could probably come up with more here right now but there's probably things that could happen that we don't even know about because we're so far from a climate system that we've ever experience so i want to global cooling that you get from addition of these particles are completely wrong so why is that well if you change the reflectivity of the stratosphere that's great those are photons now that are bounced back into space those are also photons that don't make it down to the clouds that are below that would have otherwise bounce them back to space anyways so it's called the cloud shielding effect you lose a little bit of the scattering that you would have had by underlying clouds or ice because you've already done it in the stratosphere so you've done something that would have happened anyways it cuts in the your margin by about thirty some percent so most projections of geoengineering cooling are about thirty percent too high and that was shown a few years ago  but unfortunately proponents have not picked this up and they continue to write the values as if they just turn down the sun for example as opposed to thinking about those underlying clouds this is a paper by dan murphy and so in this he shows for concentrated power the type of thing going on in places like arizona thought of for concentrating solar energy melting salts that type of thing that the loss of direct beam actually cuts into the margin so much that this becomes an ineffective technology it certainly works in the same way for photo c by reducing the amount of energy that's produced precipitation changes if you put those particles in the stratosphere one of the things we started talking about is that as we change party on the surface of the planet they make their way into the atmosphere they find their way in the clouds as the seeds on those clubs if you put those particles in the stratosphere they have to fall out what do they do they change cloud properties that's not one of the things that's modeled this  and ten looking at precipitation changes this is from stratospheric sulphate this is from changes in marine clouds these psalter ships that i showed you earlier under zero is a drought does anybody see where a large drought is happening when you change marine clouds which exist off of the west coast of south america that's the amazon rain forest that's a little important for the oxygen budget of the planet and so you induced droughts in cases like this i mentioned that there is good knowledge from the ozone hole days work that paul crewdson did himself the particles in the stratosphere act as sites on which chemical reactions take place that chew up ozone so these are all of the different materials that do that i'll call your attention to a few of these things so these are nitric acid and water so here gas and water ice is a lot of these are high drain of materials nitric acid try measurements from satellites pinatubo goes off it puts those particles into the stratosphere satellites measure ozone going down over a period over the time period after those particles are present so if you want to put so few  material into the stratosphere we know from pinatubo from other measurements that ozone would go down as a result so recently some scientists up the river this is david keith frank as well as others propose that maybe we could put materials that are reflective but that don't deplete ozone into the stratosphere so they propose putting in something like calcium carbonate which would react with different chemical some of these acids and perhaps pull out so if you're a cascade or nitric acid in this series of chemical reactions so bingo everything is solved you've got a reactive particle that doesn't deplete owes on the other side effects we talked about are still going to come into play the problem is that they didn't acknowledge what the proper phase of those materials were in the stratosphere so we're in a room right now there is a di hydrate of calcium sulfate all around you it's called gypsum it makes dry wall dye hydrate of calcium sulfate the stable form of all of the materials on the right hand side and here are hydrates or liquids in the stratosphere those are high draitser in the stratosphere depleting ozone so the  these are the well known phase relationships the hydrate formations of things like calcium sulfate and the hydration of calcium nitrate so a lot of these sort of miracle particles that are going to reflect radiation but not do anything t ozone actually don't exist in that form whatsoever and it's actually kind of stunning that this was missed in a paper that's cited is in this about women's i should mention a lot of this work on hydrates at low temperatures and low pressures is actually also known from studies of the martian atmosphere which again was completely missed by the authors of that paper so to start to wrap up my last few minutes this is part of that national academies report about the benefits and costs of carbon dioxide removal proposals and the benefits and costs about the don't modification proposals to sum up i want to say something that i said earlier coming back said removal proposals probably pretty costly for tonne of carbon but we've we've seen our climate system ramp up from two eighty to four hundred parts per million carbon if we remove it we have a pretty good understanding of going back down that ramp now there might be switches that were flipped there might be jumps there might be nonlinearities that would happen i'm not discounting that  certainly could happen but walking back down that ramp is a lot more certain than going into a completely unknown part of the system or part of our climate system high particle loadings high c o two  incredibly cheap you might get a lot of bang for your buck you might get real temperature reduction for a very small amount of money and so that's something that has to be sort of factored into the equation so just to make one final point and then i'm going to turn it over to you guys for some questions and questions that i would like to ask you because i don't have all of the answers i'd like you to understand the climate that we're living in not the temperature climate but the political climate and i try to stay away from politics as much as i can especially in class but i think reform like this you guys have to be aware of what's going on this is a direct quote from republican lamar smith who is retiring actually i believe at the end of the year tw twelve i believe climate change is due to a combination of factors including natural cycles sunspots and human activity the figure that i showed you earlier shows scientists clearly showing that natural variability is not to blame for temperature rise that is not true that is not scientific there is no basis for that it is only the third thing on there is only human activity since it's only but the vast majority of its human activity you saw the size of the air by as you saw the size of the effect it's been calculate fast forward to last fall when people went in front of congress and talked about geo engineering in our smith says is worth exploring and that the technology could have positive effects on the earth's atmosphere such as reducing global temperatures  purpose of this hearing is to discuss the viability of geo engineering the hearing is not to put a platform to further debate about to further debate about climate science or climate change so you have one of the leading political skeptics climate saying that we should explore geo engineering as a way to offset this temperature rise that apparently is not due to us but is instead natural in his opinion at the heart of this so you guys need to be aware of this that although there is science behind the idea of that we have come to some decision about what to do with this technology is is not in place whatsoever and i think this is a great fear and one that folks should be that should have is that you could mask a temperature rise you could mask the emission of fossil fuels by doing something else to the atmosphere instead of looking at what the underlying problem is the release of those emissions and the removal of the products from the atmosphere i ask you a number of questions because i don't have answers to these how much are you willing to pay for the solution of climate change you want the more costly one or the cheaper one have we shown that the cure is better than to the disease are we are we willing to say that the masking of a temperature rise is really better than the side effects is masking temperature rise really the same as inadvertent modification of climate the global warming that we already have in place and something that we didn't have a chance to talk about tonight is our use or are you comfortable with models of what climate is going to do in the future we have models that say weather modification works but no scientific basis to show that that's the case and then finally if this is a last resort if you know we're so stuck the temperature is gone up you know five years ten years in the future we see this huge spike in temperature are we confident that this is going to work out so i don't have all the answers i personally and again this is my opinion  luckily i'm a person at the front of the room but i'm willing to stay around as long as you like to tell me your opinion it's a format that when there are nonstarters for me as a scientist here if you talk about creating droughts in areas or floods in areas i'm not ok with that if you're talking about climate winners and losers i'm not ok with that certainly if you change over his own i am not ok with that if you increase the rate for example of human skin cancers as a result those for me are all  nonstarters i'm willing to pay more money to do the research look at carbon sequestration as opposed to modification but everybody has a different set point everybody is going to feel differently maybe two of those things are not nonstarters for you maybe there is more nonstarter you that's for everybody to decide so hopefully i've tried to lay out the case both ways and you know you may come to an opinion that's different than mine and i'm going to respect that opinion but hopefully you have the scientific basis behind that now so thank you guys for your time and i take any questions you got