Remarks
Dr. Darin Toohey
Washington, DC
April 24, 2012


E. William Colglazier:

Welcome everyone! We're glad to have all of you here for our Jefferson Science Lecture. My name is Bill Colglazier, the Science & Technology adviser here at the State Department. One of the pleasures of my office is helping be the steward of the Jefferson Science Fellowship Program. For those of you that are not aware of it, it's a program for bringing senior, tenured faculty from major universities in the United States to come and spend a year working at the State Department and then be available for a number of years after that and being a consultant. This year at the Department, we have thirteen Jefferson Science Fellows, actually eight working in the State Department and five in USAID. We'll have a new class that comes in at the end of the summer. Thirteen again and they -- one of the things they get to do is to decide where they get to work at the State Department after talking with a number of offices. The talk today is by Darin Toohey, he's a distinguished professor in atmospheric sciences at the University of Colorado at Boulder. Where he chose to work in the State Department in one of the regional bureaus, in East Asia-Pacific. He may be talking a little bit about some of the things he's done here, although primarily about his own research. But one of the areas where he's worked here at the State Department relates to APAC, this big consortium of governments from the Pacific region and the next APAC meeting is going to be in Russia. A lot of planning going on in getting ready for APAC and so he's been heavily involved in that. As I said, he is a distinguished atmospheric scientist. His talk today is going to be about canaries and coal mines.

[applause]

Darin Toohey:

Thanks. Thanks, Bill, that's a great introduction. I like the word distinguished. It might be the first time that that's ever been used in my title. So the first thing to note here and Bill mentioned the part about whether or not I would be speaking about the work that I might be doing in the bureau, I have a hunch the answer is no, but if I do catch any things here that might overlap, I'll let you know. Because the idea here is to give you a sense of the kind of work that I do outside of the State Department. I will admit before I launch into this that I did have an interest when I did come here to talk about some of the things that I've been working on other than just what I'm doing in the EAPM, in the economic policy office, EAPEP. And I do want to mention when I get to this near the end that some of these opportunities that I've had as a Jefferson fellow have informed some of the thoughts that I have here, in particular the end on geo-engineering, which is something that's starting to bubble around and bubble up here and there around town. But note at the bottom, the key here is that this is work that's primarily work that I've done in research. And it goes back, in fact, to when I was a grad student, and I'll point that out to you. So it's ancient.

Here's my outline. It's pretty simple: I'm going to give you a bit of a timeline on stratospheric ozone. That's probably just a warm up, so that I don't get nervous. It's the easy part. I'll give you some stratospheric basics here. When I teach classes, these are the sorts of things that we expect our students to know. And then I'm going to make that transition into Earth's temperature, volcanoes, and sulfate. That's really the piece that gets us into this notion of using the stratosphere. Use is probably too strong a word, but exploiting the stratosphere for other means here. And that's where solar radiation management comes in. And that's a new terminology, I think it's probably more politically correct than “geo-engineering.” Some people don't like that term. But I'll then give you a quick lesson from rockets, that's the work that I've been doing recently. Actually, may not be so quick because it's the stuff I'm passionate about. And then finally considerations and conclusions. This is really a new dialogue for me so I don't know if I have a lot of conclusions, but I certainly have a lot of questions. And I probably won't frame them that way, but we'll see how it goes.

So here's a timeline and it's almost proportional. In other words the distance between those years is about right. I tried to use a ruler here. It gives you a sense though. Take a look at the dates. This gives you a sense for how long scientists have had an appreciation for ozone in the atmosphere. Remarkably, ozone was discovered in the 1700s and it was discovered because it smelled. The electric-train smell that some people refer to, although that tends to have copper in it as well from the rails that are often -- copper lines that are electrified. But the thing that was interesting is Van Marum was aware of this and he essentially looked into the properties of ozone. And at the time it didn't have a name, but it was given a name from the Greek "to smell", which is ozein. And that was Schönbein that did that. And amazingly enough, within about fifty years at a time when the Industrial Revolution was sort of starting, Von Siemens -- and somebody can correct me if I'm wrong but that's probably the Siemens that is named for Siemens Industry. It could be, I'm not sure -- but makes an ozone generator in 1857. Clearly a discharge, taking electricity, discharging air, and making ozone, this smelly stuff. And I say very likely a discharge because oxygen itself, you'll see here, was not isolated from air until 1877.

So it wasn’t known that oxygen was a component of air. People understood that there was something there in the air and they knew it had to be -- they gave it a name, but they didn't know how much was there until they started isolating it. And you can see that that was almost a hundred years after ozone was discovered. Believe it or not then water purifiers came around in 1907 so it's been a hundred years since a water purifier was developed from an ozone, that was Otto who developed that. We Know have those, you can buy those. You can even get air purifiers, I wouldn't recommend you do it. The air purifiers that use ozone are awfully high in concentration, there are people who I work with at CU that think it’s a bad idea to breathe that much ozone. Look at the 1900s here, and if you take a look you'll notice that Dobson, Gordon Dobson, was a spectroscopist and he developed an instrument which exploited the ultraviolet absorption properties of ozone and that was back in 1923. And he was able to deduce back then that air rose in the tropics and descended in the polar regions and I'll come back to this in just a second.

It's the upper atmospheric circulation that's really critical for understanding how climate, ozone, radiation, aerosols et cetera interact in the atmosphere. And amazingly enough, I keep using that term, this was also nearly a hundred years ago before we really had an understanding of how ozone was formed in the atmosphere, and also its fate in the atmosphere. And yet Dobson was able to look at what we say are “column abundances.” How much ozone is there between you and space. He could look at the sun with this spectrometer. He could measure how much absorption there was due to ozone at a particular frequency in the spectrum. And then he could tell in the tropics there was more ozone -- well actually there was less in the tropics than there was in the polar regions and the reason was because the air was rising in the tropics, it's ozone poor and I'll explain that in just a bit. And when it sinks in the polar regions as it descends, it compresses so there's actually a thicker layer in terms of concentration. So a thicker amount between you and space than there is when you're in the tropics. Oh here it is, it's in this pocket. That was smart. It was somewhere there -- too many pockets in suits, you know. Usually I don't wear these things, back at the university.

Interestingly enough, it was around the same time, 1920s, when Midgely, at DuPont, invented or created chlorofluorocarbons. And of course DuPont eventually patented those and those were used for refrigerants or air -- back then it was for refrigerators. It was to replace things like SO2, sulfur dioxide and ammonia. Could you imagine, you kind of already know those probably don't sound so great. But those of us who are chemists realize that they're toxic and in fact fatal if you breathe them in high concentrations. And there are sad stories about people who died because their air conditioners or their refrigerators -- back then refrigerators -- broke open. So it was also around that same time in the ‘30s that Chapman, Sydney Chapman, recognized how ozone appeared in the stratosphere and he was able -- and these little diagrams are just to -- for those who might think pretty pictures -- it gives you a sense for the reality here. But this here is the first chemical, and I won't show you many chemical equations, in fact I think I have no more. This gives you an example of balance. I'm going to refer to balance quite a bit in this talk so that you understand that a lot of what happens in science presents a balance in-between formation and loss, creation and destruction. In this case, ozone represents a balance between formation by ultraviolet light which breaks down oxygen in the upper atmosphere and then reactions, which in this case it's catalytic. There are species that destroy ozone by reacting with it.

In fact it was in the ‘50's when that was first proposed by Bates and Nicolet, two chemists. This is an example of what water does so I lied, here's a second set of equations. You don't have to know them, but this shows you that hydroxyl, in this case the hydroxyl radical, reacts with ozone or hydrogen atoms react with ozone and make the hydroxyl. There are a number of reactions that form these catalytic cycles we call them, that destroy ozone in the process. The net reaction is to take an ozone and an oxygen atom which is a potential ozone molecule and recombine them into oxygen. In the ‘50's, so now 50 years ago, Joe Farman from the British Antarctic Survey got caught up in an experiment called the IGY and said well since Gordon Dobson had this interesting spectrometer 20-odd years ago, let's put it somewhere. And so we'll put it down at Halley Bay, which is a station that was manned by -- or crewed by the British. And so he started making measurements of ozone for no particular reason really just because it could be done. And there was no thought that anything would happen it would just be interesting to see ozone over Antarctica over a long time.

And around that time chlorofluorocarbons started finding popularity in a lot of different applications. This is called "Happy Hair," it's a spray can. There was an interesting movie made in the late ‘60s about spray cans which I saw a few weeks ago which was kind of prescient actually. Didn't really say they were bad at the time, it was in the late ‘60s, but these products were exploding in terms of their use and application. And then around the late ‘60s there's this supersonic transport comes in, I've put a little circle here, the banned sign. Supersonic transport was actually not banned because its emissions and their effect on the stratosphere but there's a popular view that that was the case. Turns out they were primarily -- the production was stopped because they were pricey and it didn't look like the market was going to pan out. And then colleagues of mine at -- I've actually met a lot of these -- not the ones from the previous slide, I didn't meet any of those, but --

[laughter]

I've met Joe a long time ago and Ralph Cicerone, who's here in town the President of the National Academy. Ralph was one of the first along with Rich Stolarksi to surmise that this beast here, the space shuttle, might actually put something into the atmosphere that didn't -- in this case it would be chlorine, which might destroy ozone through these catalytic cycles. Again this balance that I'll get back to in just a second. At the same time, Sherry Rowland, who sadly we just lost last month, and Mario Molina, who also spends quite a bit of time in town, serves on presidential commissions and such. They surmised that it wouldn't be something like this that would eventually be the problem or this, it would be that. So that little thing there, you've had a few billion of them, or 100 million of them, that would probably release enough material, far more than these would ever release into the stratosphere. Interestingly enough, you don't spray the can in the stratosphere, you release it at the surface, it gets into the stratosphere. Okay, so in that sense that issue was a new issue for mankind to be thinking about: how are our activities at the surface affecting something very high up?

And just a few years after this, about a decade, the ozone hole was observed by Joe Farman. Now he didn't see it this way, this is from a satellite recently, and it's obviously not what it looks like, it's not a color photo, but image using -- taking data and showing you blue is where there's very little ozone and green where there's a lot. But it uses the same technique that Joe Farman was using, that same Dobson-type absorption. So it was actually Joe Farman who is credited with discovering the ozone hole and then in 1985, 1986, that's when all the activity that had been occurring for many, many years in stratospheric ozone coalesce and that's when I got dragged into this. I was a grad student at Harvard, I worked for Jim Anderson. And Jim Anderson, Susan Solomon and Bob DeZafra and Phil Solomon -- a different Solomon, not related -- we were all part of -- I was under Jim. We were all part of a group that was studying this by flying aircraft or launching balloons and such. And this just happens to be our data which shows in the ozone hole when you flew an airplane across that boundary that ozone dropped as you'd expect in the ozone hole and chlorine rose, and that was then the proof that was needed, the smoking gun that these things here which were the source of the chlorine were in fact the cause of the ozone hole. And we did that work in the Arctic and the Antarctic and that's the aircraft that we used.

So that's a long timeline and it's there for me to break the ice a bit but also to sort of cast those issues out there, lay them out there for you so that we can come back to them as this talk goes on. So what did we learn from all that? One of the things to recognize is billions of dollars are spent on science trying to understand ozone depletion, especially after the ozone hole is discovered. I can say billions because there was a few satellites that were put up, okay? And those satellites were a half-billion or a billion and a big upper atmospheric research satellite, which was launched in the early ‘90s. And it turns out that as a result of all of that, I think it's a safe bet, and I would take the bet to say that the stratosphere is the region of the atmosphere that scientists, atmospheric scientists, know the most about. We can probably predict its behavior. There might be some surprises, the ozone hole was a surprise, but we know how it behaves and we know an awful lot because of all this intense study and this amazing "canary", if you will, the ozone hole. It was essentially a warning that something was happening that we didn't quite understand. And it was studying that problem that eventually led to this incredible understanding.

So what do we know? We know that warm air rises in the tropics because it's heated, it's light, it becomes light, it expands because of the heat, so it rises. Cool air descends in the poles, so you get a circulation that's called “Equator to Pole.” So air from the upper tropics and high in the atmosphere and the higher you go, the more air you get that goes towards the polar regions. Air then at the surface comes back from the polar regions, back towards the tropics. We tend to call it the Hadley Circulation, but that's simplified for those who know a little bit about that. Oxygen, UV radiation then breaks down the oxygen molecule O2, leading to ozone, don't worry, you've got the chemistry, it's not that tricky, but my students hate it when I expect them to spit it back. Absorption of UV is what heats the stratosphere. This is pretty critical, so it's that ultraviolet and a little bit of visible in fact that gets absorbed in the stratosphere which creates a warm layer there. Warm air on top of cold air is stable, so the cold air below it cannot rise, it's more dense so it's stays below. So the stratosphere is a stable layer. It's stratified, it's where it gets its name.

And then ozone is destroyed by chemical reactions of trace compounds, like nitrogen oxides, hydroxyl, chlorine, bromine, and things like that. Here's a kicker, here's an interesting twist. While the stratosphere is heated by absorption of sunlight, it's cooled by the presence of infrared active gases, like water and CO2, methane. Okay, we'll see those in just a second, they're the greenhouse gases that we worry about for Earth's climate down below. But it turns out that that gives us a very interesting proxy for understanding whether or not this global warming stuff is real. The ozone layer, by the way, is a balance between this formation and loss, this chemical formation by sunlight and this loss by chemical reactions.

So why is there an ozone hole in the polar regions? Well the main reason is you have no formation of ozone. There's no UV light there because it's all absorbed out of the atmosphere by the time the light goes through that long slant column, that long angle that you get by the time the sun hits the polar regions, the Earth's curvature and all. So it's only produced by transport. You can only move the ozone that you made in the tropics and push it using air motion into the polar regions. But it turns out that when air sits in the polar regions, it radiates through the molecules, these methanes, these waters, these CO2s, they radiate any heat that they have back to space. And when they heat that radiation away, they cool and when they cool, there's a little bit of water in the atmosphere and a little bit of nitric acid it turns out, which is critical. Little bit of sulfate. And those compounds form little particles, little droplets, or little ice crystals. We call them polar stratospheric clouds, that's a picture of one. You see them when the sun's below the horizon because they're so high up. Sometimes they're called nacreous clouds, but there's different types of those.

Anyway, it turns out that those ice crystals do very strange chemistry. And it's really a perfect storm to describe how the ozone hole forms. There's a number of steps that each one of them, if you took them separately, you would have been surprised in the chemistry world or in the Earth science's world that these things actually occur, but it turns out these three or four steps all occur and that perfect storm happens every winter in say July, August, and September. When the sun comes back you start to see this ozone destruction through these chemical reactions, primarily chlorine and a little bit of bromine related. So that ozone hole, as I mentioned, was the canary in the coal mine here. It was -- I remember the time when I worked -- I was up at Harvard and as a grad student I taught with Mike McElroy, who is a professor there who teaches general science courses among other things. And I remember him coming into our exams in January of -- I think it was '86. I was on crutches. I had had some surgery, and he -- it was '85 actually. And he said - -I remember now, the year after 1984. And he came in and he said to me "Have you heard about the ozone hole?" And I sat there and, I mean, it sounded strange. It was the most bizarre thing I had ever heard. He described to me what was going on and when I heard about it, I realized you know, 50 percent of your ozone lost in a month is a really, really big deal. And at the time, nobody knew what it was due to.

Within several years, two short years, scientists were able to figure out what caused it. And Susan Solomon is the first to have done that. She went down to Antarctica and made measurements looking at the sun, the nice dim sun that was down there and recognizing that chlorine was not in the right form. She didn't know exactly where all the chemistry had gone at the time. She didn't know what all the reactions were, there were still some issues, but she's the first, and she's gone a nice -- there's a nice display with over here at the Museum of -- American History Museum shows her and Dave Hofman wearing their cold, funny boots and their white shoes and their red NSF jackets to represent that first discovery in 1986. So one year. Ozone holes seen in '85, explained in '86. Quite remarkable.

How did that happen? It happened so quickly because of all the work that had gone on. As I mentioned before, this is probably the most studied region of the atmosphere. Certainly by then it was the most studied region of the atmosphere. We knew far more about the stratosphere than we did about the troposphere. And, by the way, why was that? It was because of rocketry. We needed to know what the chemicals were in the upper atmosphere in order to understand friction, in order to understand pressure, density, in order to figure out a launch trajectory when we put fuel -- well, I didn't. But when people put fuel in a rocket, they needed to know how high it would go. So the upper atmosphere was very important for rocketry of the '50s and the '60s. So here's a few concepts I want you to think about as we go forward here and think about climate. The first is here -- well, just balance overall. You know that a position of something depends on the balance of forces, and we know that if there is a force acting on something it will move, okay? So if we push left, it will go left, if we push right, it goes right, et cetera. The same is true for chemistry. If we push something in a given direction, we'll see chemical change, and if we pull back, we'll see it change the other direction.

The idea here is that in the upper atmosphere ozone is what we say is in “steady state,” mostly. Except for this ozone hole which has forces out of balance, if you will, pushing and pulling. In this case the reactions, the loss, are pulling the ozone away, depleting it. We see a drop in that case. If they're in balance, we see a steady concentration. And if we see formation exceed loss, then we see -- production exceed loss, then we see a growth in concentration. So, in the atmosphere, mostly, and in the Earth science in general, we often try to deal with balance. We deal with the concept of balance. We try to think as chemists and physicists "What are my balance of forces? What are my balance of chemical reactions?" And that's kind of how we looked at the ozone loss problem, and it was pretty simple to realize back then that there was obviously, for the ozone hole there, there was an out of balance situation.

You can do the same thing with temperature. You can look at Earth's temperature. In fact, it's even in more balance. It tends to -- temperature tends to react pretty quickly. If you were to brighten up the sun somehow, the Earth would warm up pretty fast. That temperature would then move around if you will. You move that heat into the ocean and melt glaciers and things like that. So, the opposite would be if you dim the sun or you somehow were able to somehow able to reflect light back to space, and that will be the theme here for the second part here, you could cool the Earth. So thinking about those balance terms, I thought this would be a good -- I haven't done thing before, even with my classes, but -- a bit of help here from John Lennon, it's one of his drawings. This is a drawing when he had been to Egypt and you can see the pyramids here.

How many of you have thought about this? On a typical sunny afternoon, and let's even pick Cairo because I'll show you the results in just a second, why do you feel warm? And I've used sun on purpose. So, what do you suppose is going on there? Well, it should be pretty obvious, right? You're warm because the sun is on you, right? So, let's look at that. Earth's heat balance, if you look at this in terms of science-y numbers, watts -- watts is a power number, how much light in this case is hitting you. You can see the lights on me. There's a certain amount of watts and there's a certain area that those watts hit, per square meter in this case. We can use those terms, and this is Cairo, it's whatever month, January through December, going this way, and there's your time of day, so let's say three or four in the afternoon. And if you look at the colors, you get about 500 watts per square meter. What's that like from direct sunlight? Well, here's John helping us again. This is, in fact, like standing five inches away from a 100 watt light bulb. And I have to be careful now when I give these kinds of lectures because I have to let you know that's an incandescent light bulb, you know, the illegal ones you're not allowed to buy anymore. Laugh, yes.

[laughter]

It's not true, but we can go onto that another time. But think about it. Most of you remember what a 100 watt light bulb would be like, okay? That you'd feel this. It'd feel pretty warm. And it's not a bad analogy. Put 100 watt light bulb about five inches from your face and it's like standing in Cairo looking at the sun in the afternoon, alright? But recognize that there's no light bulb behind John Lennon here. It's just this one, and so the backside of his presumably is freezing cold because there's nothing hitting it. And -- it's like the dark side of the moon. It must be freezing cold, right? And this side of the moon must be really hot. In fact, it's kind of true. The moon, one side is cold, and one side is hot. So you'd think the same thing would be true if you were standing in Cairo. But there are these guys. There are all these molecules. And these molecules in the atmosphere absorb heat from the surface or where ever they get it from, from the atmosphere. And they radiate it back. And what's interesting if you look at how much radiation comes from these molecules, the amount of radiation is around the same amount, okay? A little bit less. Three hundred and fifty watts per square meter. If you were a meter square, if you were a meter by a meter, then you would be feeling 350 watts, but you would be feeling it on both sides. You'd be feeling it on the front and the back because the atmosphere is all around you. So that's double what you get from the sun's 500 so you can think of that as being 700 versus the sun's 500.

So, it turns out that that's our greenhouse effect. That's what we call the trapping of infrared radiation. It's not the greatest analogy, but it's not bad. That trapping of heat and that re-radiation is what makes you feel warm. And so, if you think of -- if you do this for the whole Earth and you take an annual average and you take the entire surface of the Earth, you find out that only 168 of these watts per square meter are absorbed by the sun, or from the sun by the surface and you see that you get 324, almost double, from the atmosphere. So the atmosphere is what's heating the planet. It's not the sun, primarily. Two thirds of the heat that we feel is due to the atmosphere radiating, and the other third comes from the sun heating the surface, which then creates this heat that the atmosphere traps, right? So it's -- think of this that way, two to one ratio. We can use this balance I talked about to ask a question.

Scientists did this, Princeton primarily. Princeton scientists did this in the 1960s. They asked the question "What would happen if we keep adding greenhouse gases to the atmosphere?" So you know they'll trap heat, so the surface ought to get warmer. But there's a lot of weather at the surface. I just used the Keeling curve in the back, sadly, just for a reference. I'm not going to talk about the Keeling curve, but some of you may know it. The climate models -- as the CO2 builds up in the atmosphere, the climate models predicted something very interesting. Rather that heating at the surface only, they also predicted that the upper atmosphere would cool. And I remember this at the time, certainly in the ‘80s when people starting thinking about this problem that a lot of people thought this was crazy. Why doesn't a greenhouse gas heat the atmosphere uniformly?

And it turns out the data now, bear this out, this shows you the upper atmospheric temperature over time, and you can see a decrease starting in the '60s, when measurements were available. So you can see this continual decrease, although something interesting's going on here. But notice the general decrease of about two degrees in the upper atmosphere of temperature and here's the surface temperature. And you'll notice back in the '60s and up till 1980, there wasn't much of a warming trend, which is why we got into that argument of "Is there really global warming or not?" You may remember that story. Some scientists saying we're actually going to have global cooling. We'll go into an ice age. And here's where the warming really kicked in, in the '80s. But you can see the cooling was already there in the '60s and '70s in the upper atmosphere. So, again, the stratosphere is that canary in the coal mine. It's the place where the action's happening first. And the reason for it is pretty simple.

It's the balance between this heat, the absorption of light in the upper atmosphere, as I mentioned, the UV and a bit of visible light that's absorbed in the upper atmosphere. And it's that cooling by emission of these greenhouse gases. If you increase the greenhouse gases, you increase the emission, more emission means more cooling, so you get a lower temperature. So it's a bit of an oddity, but it was the first signature, the first fingerprint scientists had that said there must be a change in the Earth's temperature balance due to rising greenhouse gases. And therefore, we may eventually expect to see a change somewhere else, like in the lower atmosphere, and we've now seen that example in the lower atmosphere where it's gotten about half a degree or a degree warmer in the last fifty years or so.

So we've got this balance concept, let's accept for now the fact the Earth has had a warning, whatever that's due to. We know that Earth's surface now we've seen warming over the past twenty or thirty years, and let's now think about what we might be able to do with this concept of balance. I'm taking this figure from before and I don't expect you to know all these details. There's this term over here that we have to be wary of, or think about when we're talking about Earth's temperature, and that is that the reflection of solar radiation. Okay, so if we had more clouds the surface of the Earth would appear brighter from space, more light would be reflected and the Earth would not absorb as much. This number would go down, the reflection would go up, and presumably the Earth would cool, right? Take a little bit of time for that adjustment, but it would happen.

So you could imagine, now, a thought experiment. And this is where geo-engineering comes in. It's not a stretch, Edward Teller was one of the people to do this actually. Edward Teller, the famous Teller who thought of taking a nuclear weapon and blowing up a glacier in Alaska to see what would happen. He also -- and I may have twisted the story a little bit, but that's the way it was told to me. He also thought we could add lots of stuff to the upper atmosphere and we might be able to create a reflective shield and we might be able to cool the surface if the Earth were to be getting warmer due to greenhouse gasses. So he was very forward-leaning about that. That was twenty years ago almost when he thought of that, fifteen years ago. There were other people before him, too, Freeman Dyson is another person whose name is associated with this concept of changing the Earth's albedo, the reflectivity in order to cool the planet in case something were to go wrong.

Do we know whether this would work or not? And the simple answer is yes. Nature did the experiment for us a few times, this was probably the most dramatic that we remember in terms of recorded history. In 1816, there was “the year without a summer,” it's Mount Tambora in Indonesia so now I'm getting into the East Asia and Pacific Affairs stuff, so. If anybody thinks that's wrong, we may have to re-clear. So, but I think it's right. It turns out on April 10th it was the largest -- well, 1816 was without a summer, 1815 was when the eruption occurred. It's critical that these volcanoes erupt in the tropics in order to follow the circulation through the atmosphere. If you erupt in the polar regions, like there have been recently, like the one in Iceland for example, that people thought would be a massive, certainly was massive for aircraft in Europe a couple years ago. Maybe it was only a year ago. It turns out that the problem there is that the air circulation brings that stuff right back to the surface, it doesn't loft it up very high. So you've got to erupt these volcanoes explosively and high up into the atmosphere in order to see that global transformation of aerosol. But this is a painting at the time, and I'm sorry I don't attribute it, someone here probably knows that, and I apologize that I don't. But this is a painting showing what the -- I think it's Europe, showing you what the skies look like during the year without a summer. Although it looks pretty summery there so not sure what's going on. But take a look at this, I've never lived in New York City, I grew up in Los Angeles. So I'd be curious to know what the temperature was there, but there was recorded temperature of minus 26 Fahrenheit in the winter of 1817 and there was snowfall in Pennsylvania in the summer of 1816.

So this was an experiment that nature conducted. Nature did it again in 1991, we were ready. Of course we didn't have the technology in 1815, but in 1991 we had the technology to fly up in the upper atmosphere and take some measurements. And to see what was actually going on and I was part of that. But there were a lot of things going on, this is a satellite, a communications satellite that was looking down at the time. That's showing you the sulfur dioxide cloud that encircled the Earth in the tropics and then over the next few years it spread. And as it spread across the entire world, it added a little veil, shielding the Earth from just a tiny bit of radiation, maybe one percent or half a percent. And that was enough to change the surface temperature by about a half of a degree. It was twenty million tons of sulfur dioxide. This is going to be really important in just a minute because this is going to tell us how much our own experiment will cost if we decide that we can mimic a Pinatubo. We're not going to do it this way probably, we're going to do it with airplanes. And this is all the chemistry that goes on and stuff. But the idea, you have a gas that creates a little aerosol and that -- those tiny particles cover the Earth and they act as a small shield. They do lots of other things, by the way, they acidify rain, they change clouds, they do all kinds of crazy stuff.

This shows you what it looks like in the Earth's temperature record so this is that record I was just showing you. I showed you the surface and you didn't see much of a change from say ‘40 to ‘60. Here's where most of the temperature change in our lifetimes has come or in our generation. It's all happened since about the late ‘70s. So there's about a degree of warming or almost half a degree of warming since then. We usually say that there's one degree of warming since 1880. But here's what the Pinatubo did, these little drops, that little drop, that two year drop was what that 20 million tons of sulfur did. It dropped that temperature about three tenths of a degree centigrade globally. This is a global average.

So the last bit of my talk here then is to say "Okay, what if?" So we've got this understanding of the upper atmosphere, we've learned about, and I can't even -- it might take me another day to give you all the science that we've learned over the time, over the last twenty, thirty years studying this stratosphere. But the hope is here that I've given you some sense that we know a little bit now from understanding the ozone hole and other issues that we studied at the time, we being the large scientific community. But there are people who now think we ought to do -- well, I shouldn't say ought to do the experiment, but we ought to consider this as something that we should know about. It's not something that we should leave for someone else to do. This is something that the scientific community should try to look at and that's geo-engineering. And so I'll just read this.

So first issue here is that nothing should divert us from the main goal of reducing our greenhouse gases emissions. That's what is causing the warming at the surface under the global warming hypothesis. And so therefore that's what we should be looking at, right? But what happens if we don't solve that problem? There may become, and in this case this particular report came out of the Royal Society in London, said that there was surely going to have pressure to do a Plan B. Seek ways to counteract this warming at the surface. So I've just shown you a great way to do it: put 20 tons of SO2 or something similar like that in the stratosphere. And you can expect maybe half a degree of cooling. It will go away after a few months or a few years, but you do it again. It's a great job if you want job security.

But notice the bottom here. Further research and development should be undertaken to investigate the risk of these things. So if we don't understand climate change impact so well, maybe we don't understand the impacts of geo-engineering so to speak. So this group recommended carefully planned and executed experiments. Well this is great, that's what I do. I'm an experimental chemist. So what can those experiments look like? Well, it's making clouds in the upper atmosphere. But not all clouds are created equal. the little tiny particles that end up in the stratosphere -- the little particles, how big are they, I should give you a sense here. One micron, meaning a tenth -- one micrometer, one millionth of a meter. Anything smaller than a micron is really good at scattering sunlight. Actually it's got to be a little smaller than that. But that's a good guess. Anything larger than a micron absorbs infrared radiation. So it actually becomes a greenhouse gas-like particle.

So you want to make tiny, tiny little particles and not big ones. So you have to come up with a mechanism to do that. And then you want to create this layer that in the net it's reflecting light and not absorbing the infrared back from the surface that's what that unreadable graphic is telling you. And you want to put them all over the place, because you don't want to just do this in one spot. This is what happens if you do it in one spot. And then lots of people get angry because they see chem-trails and they think that you're manipulating their atmosphere. And you don't want any of this in it at all. The worst thing you can do in the atmosphere, especially when it comes to balancing radiation temperature, is to get any black carbon in your droplets. If you get black carbon in your droplets, they’re maniacally bad. They warm the surface -- they warm the air or they absorb light from the sun in a very, very serious way. I'll show you in just a second. So you have to do this black carbon-free. And you do this high up and you try to make really tiny particles.

So, we kind of did that experiment. We didn't do it intentionally, but there's some. Those are water particles, but those are ice crystals that came from a shuttle launch, I don't know which one. There's your vehicle assembly building. We did 135 of them and we put that many kilotons of alumina per launch. So we put into the stratosphere. So we put twenty-seven million tons of a surrogate. It wasn't exactly sulfuric acid but it was alumina. We did it over a long time, so that stuff did not form a layer that did very much. And you can kind of tell from the temperature record that it didn't cause the Earth to cool or very likely didn't. We'll find out now that we're no longer launching the shuttle, we'll see if the Earth all of a sudden starts to get super warm, but probably not. But it was an experiment nonetheless. We did this for other reasons and we put that stuff up there.

By the way, I just show you this picture because it has an interesting historical connection context. This is the launch of Discovery after the Columbia accident. This was some work I helped NASA with to image the shuttle launch from an aircraft and you can see the shock waves, which had never been seen before from a camera that was mounted on a plane flying at 60,000 feet. So it shows you what you can do if you put your mind to it and you're interested in a problem. This was to look for a piece of foam coming off of this and it found these shock waves that engineers knew they were probably there but they had never imaged them, so that's cool. But what did we do, what did I do?

So this is what I did. That same airplane that had a camera in its nose we -- this is a picture of one of the shuttles' launches I flew through. I wasn't in the plane, unfortunately, I wish I could have been. I had an instrument out on the wing and this is the airplane leaving the contrail at 60,000 feet, 55,000 feet, and this is the shuttle plume. So you can see how big it is. This thing grows and expands and we flew through it to see how the particles would evolve. So we were doing this at the time we didn't want to say the word geo-engineering. We didn't think it was prime time. But we knew what we were doing. We knew we were setting the stage for doing experiments that if we ever needed to go out and look at an event, like another eruption, like an experiment someone felt like conducting, adding gas to the atmosphere that turned into particles, we have the capability to measure it quickly. We did this with something like one day's notice, two days notice. Put the instruments on the plane, got it out and flew the plane. And so that's the trick. The trick is mobilizing your assets.

I'll show you some results, just to show you -- to make this a little science-y and to show you some cool stuff. But this was not the particles, but the particles looked very similar. This is the chlorine that's in the plume because the shuttle uses a rocket that has chlorine in it, and it's the red line. Just look at the red line and the blue line. And I'm just going to show you three passes. We had nine passes through the shuttle plume. And I'll just cycle through so there's one, two, three. So you'll notice the expanding plume. It gets wider and the chlorine goes to zero, it's the red. So the chlorine is being exhausted, it's being reacted and then it's disappearing into another form and you'll notice the blue line which is ozone shows you a complete and utter ozone loss in the plume itself. I show this because it gives you an example of what happens if you don't study a problem.

We did this work in 2000. We did it again in 2005 when the Discovery came back. We had a hiatus when there was a gap there for obvious reasons. And what's interesting here is that there was never any attempt that I'm aware of to measure the exhaust of a space shuttle back in the '80s when there was the possibility of an ozone issue in the upper atmosphere. And Cicerone and Stolarski had pointed out that there was chlorine coming from volcanoes and space shuttles and therefore you could potentially consider there to be ozone loss from them. No one apparently ever decided, if they did it's not for the public record, to fly instruments through the plume, but if they would have done so they would have seen this ozone loss and they would have been shocked. Because the chlorine that comes out of the space shuttle exhaust is in unreactive form called hydrochloric acid. No one ever would have expected it to cause an ozone hole, so when we get to that in just a second, but here's my clever slide for transition.

You guys all know the rest of the story, that when the public found out that we had done this geo-engineering experiment and we caused anomalous warming in the arctic and there were massive protests around the world. Last week, they decided that they would cancel the shuttle program. Of course, very hypothetical, didn't happen. But it's interesting to think about that and to think about the notion of doing an experiment and to show you why you do them. This is my argument why would you consider doing an experiment on something even if you think it's not going to cause a problem. So I mentioned Stolarski and Cicerone, and I mentioned the possibility of a shuttle causing an ozone loss. But what's interesting is they did not expect that ozone would happen in the plume. They expected that after many, many launches or many, many volcanic eruptions there are issues with what they were able to write back then that I won't go into here. But it turns out that with all of this chlorine in the atmosphere they surmised that there could be an ozone problem. And it turns out that this document was produced in 1985.

It was the first major assessment of the ozone, the stratospheric ozone. People in this building know it very, very well, and another four years another one comes out. And it turns out that in this document there is a very, very prominent statement by several very prominent atmospheric scientists, one whom I've already mentioned. And it turns out that the comment was we know that there's different kinds of chemistry that can happen in the atmosphere. We know that there's chemistry that can happen for example on cloud particles, like the geo-engineering experiment we might conduct or like the Pinatubo eruption. But we don't think it will have any impact whatsoever on the ozone. These reactions are not considered fast. Well it was those reactions that caused the ozone hole. And it was discovered the same year that they published that in this assessment, which was all the scientists that you could possibly imagine working on ozone at the time. And I mention this because if we had flown instruments through the space shuttle plume back in '82, '83, we would have predicted the ozone hole. We would have predicted it because the same chemistry that occurs in the exhaust of the shuttle is the exact same chemical -- set of chemical reactions. It's a different particle, it's alumina and it's not ice, but it occurs in Antarctica and it occurs in the space shuttle plume. So it's an interesting example of what happens when you're not thinking you need to study a problem because it may not be a huge problem and in fact the space shuttles overall only cause this nice, big hole, if you will, in a very narrow column of air where there -- where the gas exhaust products are, the particle exhaust products are.

So let's return back to the late '80's. You've seen this already. This, of course, was the big story for this building, and this gentlemen was key to that. This is Richard Benedick, who I think is probably world famous here, in this building. And he wrote this in his book. And this is what is really critical to end this talk, to have us thinking about. Perhaps the most extraordinary aspect of the Montreal Protocol, which was what stopped the buildup of these CFCs and did so in a very short time. The picture on the right, the graph on the right shows you what's happening now up to the year 2010, with chlorine in the atmosphere. It has turned around. We have finished that experiment, of adding CFCs to the atmosphere and we've stopped it. And he writes here that this was the imposition of short-term economic costs to protect human health, or it was as a result of that. Essentially, this whole Montreal Protocol, the last thing of the -- what I want you to read is down here. At the time of the negotiations and signing, there was no measurable evidence of damage. They started the process before the ozone hole was discovered and even when the ozone hole was discovered, there were no impacts that were known, demonstrated at all on the Earth's surface. None. Okay, and so what was going on? Well, this is what Thierry Vanlancker thinks from DuPont. The unprecedented progress on ozone layer production was a direct result of cooperation between governments, industry, organizations, scientists.

So I finish by asking you this: What are we going to do about climate change? Or what about the climate change issue? Are we in the same boat? Is it the same kind of issue, do we have cooperation like you seen here? Are we at the point where there are no effects, but we are going to act? And I think we know the answer to that. We're starting to see climate change already, I just give two great examples of melt in Greenland, this is the new permafrost melt each summer which didn't used to melt 20-some years ago. And sea ice coverage and all those things. We could talk about droughts, weird fires in Russia and all that. We could argue about what they're due to, but change is occurring, right? So this group has decided, this is a 2011 group, they have decided to write the following. It's a bipartisan commission, James Baker's commission and Richard Benedick served on it, in fact. So did my boss from Harvard, Jim Anderson, among others. It turns out the risk of climate change, if it continues to increase, well since it does here, it is happening. Although we do not know exactly how much the climate will change or how fast, we know that there could be some bad things.

So research is needed to determine if we can do something about it, either removing CO2 from the air or doing solar radiation management. So their recommendation is that the federal government should embark on a focused and systematic program of research. So that's what the research looks like, it's a bunch of airplanes. Well, the research doesn't look like that, that's what intervention looks like, research would be studying this problem before we do it. It would cost about in the $10 billion to $20 billion a year, plus some non-recurring engineering costs up front. We'd put in about as much sulfur as we'd put in for Pinatubo, but we'd make it smaller particles so they're better reflective. That's a technical challenge, but we would do it. And then here's the affordability and the effectiveness, and these are all the other options. The other options are either not as effective or they're not as affordable. So this is the best option scientists so far have come up with. I think because they understand the stratosphere so well. Here's what the experiment looks like, here's the Earth's global temperature, you start the experiment and oop, the temperature drops and then you're stuck or do you stop the experiment and get back up to where you started because you saw Pinatubo, it’s just a temporary drop.

Here's what it does to ozone, we now know that's what Mount Pinatubo did so it's not a big problem for ozone although it probably should be studied. Ozone does not appear to be as vulnerable to this as one might think because of all the studies that we've had from the ozone hole, et cetera. Are we ready to do this experiment? In other words, are we ready to start adding stuff to the atmosphere? I mentioned the space shuttle, I'm going to show you this. We're already on track for this experiment. We've already set the wheels in motion.

It's called suborbital rockets. Okay. They're going to burn -- this isn't -- this isn't suborbital. This is actually burning kerosene. It shows you what happens when you burn kerosene, you see this black cloud, that's soot. I mentioned earlier soot, not good. Soot is about a million times more absorptive to sunlight than C02 is to infrared. So, one gram of soot is like having a million grams of C02 when it comes to its warming potential for the earth. And this is what the rocket people think the future looks like for propellants and there's this hybrid which is butadiene, rubber plus nitrous oxide and about a three or a five percent emission index in some of these rockets. So we're going do the experiment once we start launching these, we've actually launched already a few. So we'll be adding stuff, it's just that it's not white, it's black so it's a different kind of experiment.

And I wrote a paper a couple of years ago showing that there are parts of the atmosphere where you will see systematic changes in temperature and you will also see systematic changes in ozone. And the stratosphere being the canary in the coal mine, we'll use those systematic changes, I hope. We'll be ready to go out and measure so that we don't have to do a geo-engineering experiment if you will, we'll just take the opportunity to fly for the next five or 10 years and look at these regions and see if we can see those signatures. Refine the models, do the experiment, okay? Do the -- you know test it, why not? This time rather than not being ready we probably ought to be ready. And we might learn something that might be useful, the canary in the coal mine comes back.

So I end with this. These are my thoughts on this whole issue now that I've been in the building and thought about it and been around to some events in town. These are cross-boundary issues. It's pretty obvious this is not something that one country thinks about on its own, you do an experiment and then you don't worry about where the stuff goes. The ozone holds an example of an experiment where we added chlorofluorocarbons in the northern hemisphere. We caused an ozone hole in the southern hemisphere and now one in the northern hemisphere but we're on our way back, we hope. Who determines the objectives of those research experiments? Who determines the objectives of the solar radiation? Is it to cool you and to warm me? Is it to warm you and cool me? Is it to save my ice and melt yours? What's the -- what are the goals? Is it fundamental or is it applied research? Is it called a process study or is it implementation? Are you doing it for a reason or are you doing it just for knowledge? What are the inadvertent impacts and side effects? That's a biggie. By the way, it's important to recognize that when you heat the surface by absorbing infrared -- and you cool the upper atmosphere by reflecting light to space or cool the surface by reflecting light to space. Those are two different processes. You're not going to get the inverse, you're going to see something quite strange. There will be winners and losers, who pays for that? Therefore funding and governance is really complex and problematic.

And then what about other activities? I mentioned rockets. Is it fair to call an experiment that you do intentionally a geo-engineering experiment and call a rocket launch something else? When they emit similar things or they can emit things that act against each other? And you have to be careful, you can't just jump in to this without thinking about it. You have to recognize the unintended consequences of your own policies so to speak.

So my conclusions then are that we have the ability to alter the planet. I think we all know that. The stratosphere has been the early warning system. We can do inadvertent and intentional climate intervention, both are possible. Inadvertent would mean doing things such as having a bunch of power plants that emit sulfate. We're not intentionally adding sulfate from sulfur in the coal, which is inadvertent and therefore it cools the planet. And there are people who think that that's what happened in the ‘40s and ‘50s, which is why there wasn't a super warming then.

We should continue to study basic things in the world to understand them, especially if it impacts our ability to do such experiments, but of course the question is should one do those experiments and I'm not the person to answer that but I have one of seven billion opinions. And due to unintended consequences I would argue that this is problematic. And we probably should think carefully and we should think really hard about our governance and there are people here and elsewhere that are doing that. So I give credit to Andy Gonzalves here who I stole that from the web. I didn't give credit to any of the other things I stole but I thought that was cute, so there's my canary in the coal mine and with that, thanks for your attention.

[applause]

So, Q&A, up at the back. And this is the part I'm not cherishing.

[laughter]

You want to go first?

Male Speaker:

No, but I will.

Darin Toohey:

Okay.

Male Speaker:

Darin, thanks very much. A great presentation. I learned a lot. Now my question though is what do you say to those people who say that you know it's our modern technology that has caused all of these problems in the first place? And yet you're going to use more technology to try to fix what technology destroyed. Why can't we just leave it to the earth to heal herself and shut down all of these operations? It's a techno fix.

Darin Toohey:

That's a great question. I'm going to defer to Jim Lovelock on this one. What a great guy. Jim Lovelock said when it came to the ozone problem, Gaia, so you all know about his book “Gaia.” That one way to solve the problem of us techno people who are altering our planet is to do away with us. Mother earth could figure out a way to do away with us so, sure. That's not an answer to your question, is it?

Male Speaker:

No.

Darin Toohey:

[laughs]

Male Speaker:

We can --

Darin Toohey:

I think it's a --

Male Speaker:

Do away with some of us but its -- you know -- a natural human population on this planet --

Darin Toohey:

Yeah, yeah, yeah.

Male Speaker:

Of two to three billion people, without all of this technology would be just fine.

Darin Toohey:

I think that the debate has to happen now and I think it's a great question. The way I look at this problem is that it's almost like the atomic bomb, right. You study something and now you have a capability, and the question is do you use it? And we have an answer to that and we have more of an answer to that, right? So it's been a while since we used it the way we did. So I think in this case, I'm not personally for a technological fix to the problem. What I am for, and I will admit this, is I'm for the dialogue because if we start putting a value to it and a price to it and if we say look at how much this costs, I think it does put in context the cost of, if you will, the alternative or the savings. If we were to do this instead and avoid this, what has the world avoided? Well there's a world avoided for doing geo-engineering experiments for example, and that world avoided looks like it's about $10 billion or $20 billion a year. I would actually argue that's a number, that number is an underestimate. I think whoever did that report, I won't say, is off by a factor of 10, but it's a number to have, it's 20 billion, it's 100 billion. At least it tells you what you might want to think about when it comes to what you're paying now, the price you're paying now for not doing anything. But I don't have an answer to the question, the way you've asked it.

Male Speaker:

Thank you.

Darin Toohey:

Thank you for asking it. I'll finish the answer at lunch. [laughs] Come on, anybody else? I'm hoping I at least got people to think about stuff. So if you're not interested about asking a question now, feel free to look me up.

Female Speaker:

Let me just quickly ask you. In terms of the political and social atmosphere that existed when you were --

Darin Toohey:

Yes.

Female Speaker:

-- canary with ongoing, I think we tend to sort of hyperbolize our own times, but do you think there would be more resistance to -- is there more resistance to dealing with our current proposed problem as you lay it out than there was at the time when you were tackling?

Darin Toohey:

Absolutely. It's a great question. I think -- it's also the case and I guess I should have had you guys tell us who you were. So anyway, that's all right. The answer is no question but I certainly remember Sherry Rowland going through an awful lot of agony. He was very good about it but I watched him. I spent nine years at Irvine, eight years at Irvine before I was in my present location in Colorado, and -- my present university. And he was very frustrated at times but I will tell you that because of that -- the cooperation that you saw from DuPont, the quote from DuPont, that cooperation mattered a lot so it's very, very different and you know, we can tell because we've been having this debate over climate change in strange ways, in legitimate ways, but for a very long time but I think it's fair. It's a much more complicated problem, you know, removing a chlorofluorocarbon, which of course will take 100 years, but having it removed from our society as a source of a problem that was pretty clearly articulated and had very few caveats really. It was really just a couple of companies making some money and there was a replacement available for it eventually, in fact probably sooner than anyone knew.

That's a big difference than this industry that we have which is the fossil fuel industry which is what you're referring to regarding the climate change issue, I think. So I think it's legitimate -- and so it's not unreasonable but at the same -- that there's this difference, but at the same time from a scientific point of view you know, it's tough to ask a scientist what should we do because the answer to us is really easy. Right? So for with the CFC issue, we remove the CFC but the C02 issue, shouldn't we just remove the C02? Meaning we don't admit it or we take it out, and so of course it's not possible, right? I mean, it would be so disruptive that you couldn't do it. So, having the debate is a good thing but sometimes the debate goes off into strange tangents that people like me don't understand. But yeah, it was very different then -- I have to say it was -- it was easy then. Thanks to people like Mac McFarlane, by the way, if anybody knows Mac McFarlane at DuPont, he was a key player at that time, wonderful guy. Norma?

Female Speaker:

That was a great lecture Darin, I enjoyed it very much and I was studying your graphics carefully because I'm not too far down the line. But --

Darin Toohey:

You can have them.

Norma:

I wanted -- maybe your iPad. I've had my eye on that. It's cute.

Darin Toohey:

Yeah, yeah, yeah. [laughter] Can't have that.

Norma:

And your pointer.

[laughter]

I had a different kind of a question. You were taking about balances of course, another element in the equation that you didn't discuss is clean energy, which is of course, coming along.

Darin Toohey:

[affirmative]

Norma:

And so, in a couple of paragraphs or less could you give your assessment of how much potential clean energy has?

Darin Toohey:

Two hundred years from now we will not be burning much fossil fuel. That's my prediction. [laughs] Oh, you want the other -- you want the other piece in between. Yeah, you know, so my view on clean energy is pretty interesting. Of course, I'm for it in its form. It's also, depending on what form that is, it's tricky of course, because clean energy is dirty in other ways, we know that. So you don't just create solar panels without digging something up somewhere else and having a problem there, so you have to be careful. But having said that, I think personally, and I don't know if this answers your question, Norma but I think that the solution's going to be an economic one. Eventually we're going to hit a tipping point where people decide that it's much cheaper to get that form of energy and they're not going to really care what it's called. And they'll buy it, they'll get it. And as a result, we'll shift into a different world and we will get there either --it'll be abrupt, I think. I think that that transition will start happening and then you'll see the exponential growth of solar or wind or ocean or whatever or a combination and eventually we won't need vinyl anymore because we'll have iTunes eventually, we won't need gas in our cars because we'll have electric batteries but I -- you've asked a great question. I mean both of these questions, all three of them actually. These are tough questions. I think they're questions we should be thinking about.

Male Speaker:

I also wanted to thank you for a great lecture. It's been thirty years since I've been in an ionospheric physics course actually, graduate school, but this was much more interesting than most of those. I have a question from a program, it might have been a PBS program that I heard part of many years ago, so it's fuzzy but the bottom line really stuck with me and it relates to one of the slides perhaps that you skipped and one of the affects you did -- you did outline and it’s the reflective potential of -- and I don't know if I have terminology right, but particulates, it was particulates, not greenhouse gases but particulates, I don't know if its aerosols or a combination of aerosols and soot or something, but the bottom line I remember very well from this program. It was very convincing at the time, that the rise in some of the -- much -- the most populous countries, in particular China and India.

Darin Toohey:

[affirmative]

Male Speaker:

And with studies that they have shown the level of particulates may actually be masking, according to these studies, the global warming effect by almost a factor of two and that one of the conclusions from this study was that as things like catalytic converters and other soot and emission diminishing technologies come to those countries you can actually see a drastic increase in global warming. Can you refresh my memory?

Darin Toohey:

Yeah, I will. And I'm sorry I went over that very quickly, through that piece. I recognized my time. Excuse me. So basically, the idea here is that the geo-engineering experiment I'm referring to is to do exactly this notion of adding particulates. Wherever you add them it's best to add them in the stratosphere because of the long lifetime. I failed to mention that. The lifetime is five years or so, three to five years, that's the recovery of Pinatubo afterwards and there's a reason why it recovers faster than five years if anyone wants to know afterwards I won't go into it here it'd take too long. But there's your Pinatubo experiment and you can see it's pretty clear, although it's about the size of the noise too. So, there's this. Why don't we have this? Why doesn't this just go up this way? Why did we wait for twenty years, thirty years and then start to go up? There are people and I'm not one of them just because I haven't written the papers or studied it, but I have colleagues who pretty strong advocates that this is due to exactly what you're referring to.

It's due to the burning of sulfur coal, high-sulfur coal which created haze around the world which offset the warming, post-World War II. There was a big revolution in expansion of the industrial world and we're seeing it now in the developed world-- developing world, we're seeing the expansion for example in say coal-fired power plants in China, et cetera. And I have had scientists, friends of mine tell me, when you give talks like this Darin, you should be really forceful about telling people that we're here right now because of we would be up here but there're all those coal-fired power plants and you should tell people that we should probably not be taking down the coal-fired power plants because otherwise we'd end up here. I've literally had people tell me that, all right? Not -- they're telling me that as the geo-engineering concept, they're not telling me because they're advocating it. They're doing exactly what you say, the particulates have probably taken a few tenths of a degree out of that rising and there are people who legitimately worry that when we start cleaning up, clean -- you know, what could clean energy mean? It could mean a super warming for a while because I go to my other slide, it's this slide, it's the finish of the geo-engineering experiment. If those haze layers or if that haze is what causing this decrease, then when we take, let's say the sulfur out of the coal in these places or if we stop emitting these materials that make aerosols we're going to get a super warming and we're going to be up to a higher point. So I think that answers it right? I hope. One more it looks like.

Female Speaker:

I just wanted to ask, so that's the consequence of these large particles but you're proposal or the --

Darin Toohey:

Small particles

Female Speaker:

Oh, all right. So maybe I'm misunderstanding. Because I thought you were proposing sticking in particles that affected the infrared as one of the ways --

Darin Toohey:

No, I don't want it.

Female Speaker:

[affirmative]

Darin Toohey:

No, I don't want to do that. I'm sorry if I gave you that impression and so we should erase that concept. I want to put -- I don't want to -- the thought experiment here is let's offset the warming due to greenhouse gasses by putting in tiny little particles way high up --

Female Speaker:

[affirmative]

Darin Toohey:

-- so that they keep some of the sunlight from hitting the surface

Female Speaker:

Okay, and it is reflected --

Darin Toohey:

And as soon as those particles get too big they now become the wrong kind of particulates and then we've got to get rid of them. By the way, I'll mention it now because it's useful. That's why Pinatubo recovers so fast. The particles grow and they get bigger and they are no longer effective at reflecting radiation back to the space and that's why the earth's temperature shows that recovery.

Female Speaker:

Okay. But there are unintended consequences that you have mentioned but you haven't gone into detail about with those smaller particles, right? Could you say just a little bit about that?

Darin Toohey:

Yeah, I'll tell you this. That if we put anything absorptive into those particles, if those particles are not purely white or clear, that's what scatters radiation best. If those particles get anything absorptive into them, like a little bit of black carbon, bad. Bad, bad, bad. And that's what we want to avoid. The sad piece is there's all sorts of black carbon around. So the question is, when you try to do a geo-engineering experiment, what is your atmosphere like at the time you do it? Is it possible that you make a cloud of bright aerosols with black carbon there which absorbs the black -- they absorb the black carbon and then they become super absorbing. That's the weird part about droplets when they absorb black carbon they become more potent. It's the same thing you hear people talk about on ice sheets and the black carbon initiative or the clean climate, I forgot. Yeah, I should know it, it's my field. It's this building. But anyway, those are all the unintended consequences that I would say are reasons why you should not do these experiments. But you should certainly try to understand what those effects might be so that you can at least intelligently argue why you shouldn't do the experiments, right? Does that make any sense?

Female Speaker:

I guess I was just wondering if you're more concerned about unintended consequences?

Darin Toohey:

Oh, yeah.

Female Speaker:

The health consequences or if you're concerned about some kind of sort of geophysical consequence that might not have a direct impact on human health?

Darin Toohey:

I'm more worried about the climate implications and the weather than I would be the health. When it comes to these particles, because we have a whole bunch of other stuff we're dumping into the atmosphere down low that will far outweigh what we put up there in terms of what we breathe eventually. So I don't worry too much about the health part. But, should we? Yeah, I mean, we should. You know you never know, like I mentioned we didn't study the consequences of a space shuttle at the beginning and we found this very interesting property later on that could have been useful. Science finds all kinds of things out by going in the wrong direction, right? Science is mostly about making mistakes for those of you who you know, hated science when you took it, it's probably because it didn't work sometimes. That's what scientists love, we love the experiments that fail because we learn something from them. I would not want to fail on this one. Right?

[applause]