Just in time for Halloween, an episode that’ll scare the daylights out of you. Frank Keutsch joins us to explain what geoengineering is, why it isn’t a magic fix for climate change, and why we still need to greatly reduce CO2 emissions.
In this episode
- Frank explains why geoengineering is a lot like using pain killers
- Frank discusses what we do and don't know about the effects of geoengineering
- Colleen and Frank talk about the steps we need to take to really combat climate change
Timing and cues
Interview part 1 (3:28-13:55)
Interview part 2 (14:46-25:31)
Note on recent news throw (25:31-25:37)
Note on recent news (25:37-27:32)
It’s getting pretty creepy here in the land of the Salem witch trials, Revolutionary War-era cemeteries, and the birthplace of Edgar Allen Poe. The days are getting darker and colder, and the leaves have fallen from the trees, leaving bare skeletons outlined against the moon.
At the Union of Concerned Scientists headquarters in Cambridge, we’re looking over our shoulders at the slowly rising tides… jumping out of our chairs each time an environmental protection is rolled back… holding back shrieks with every new forest fire, drought, flood, and unseasonably hot day.
It’s true: we’re haunted by climate change.
Like a vampire, it only comes in when it’s invited. And like a vampire, it’s hard to get it to leave once you realize you’ve made a terrible mistake.
Fortunately, we’re not powerless against the monster. There are ways to drive a stake through the heart of climate change. The single most powerful tool we have is cutting our global warming emissions, CO2 and methane—that’s the best way to minimize the scary consequences of climate change.
But is there a shortcut? A string of garlic bulbs we can use to fend off the beast and buy some time?
Our guest today is researching a tactic for stalling some of the worst effects of climate change through drastic means: solar geoengineering. Geoengineering is intervening with earth’s systems and processes, sort of like Dr. Frankenstein creating his monster.
Dr. Frank Keutsch is the Stonington Professor of Engineering and Atmospheric Science and professor of chemistry and chemical biology at Harvard University. His lab is working on SCOPEX, an experiment designed to find out if there’s any way to prevent global warming through interfering with how sunlight reaches us on Earth. Could his team’s work be a silver bullet for climate change? Or will it be more like a Hollywood thriller, with a weather machine and people manipulating the climate—and some scary unintended consequences.
Dr. Keutsch was kind enough to join me to walk me through the basics of solar geoengineering, explain his project SCOPEX, and chat with me about how these kinds of solutions for climate change are like taking an aspirin when we need major surgery. Stay tuned for a spooky show.
But first a quick note on our interview. We mention CO2 a lot, so I want people to know that we are talking about carbon dioxide one of the major contributors to global warming emissions.
Colleen: Frank, thanks, for joining me.
Frank: Thank you very much, a pleasure to be here.
Colleen: So things aren't looking promising right now for climate on our planet. Temperatures are rising. The latest IPCC report was sobering, even with very aggressive reductions in CO2 we may not get there. In any event, it is hugely challenging.
So scientists are now looking at ways to take CO2 out of the atmosphere. So one way to do that is geoengineering, why don't you start by telling me, giving me a definition of geoengineering?
Frank: The geoengineering we talk about within the context of climate, really falls into two very different categories. One category is the one you mentioned about, is this idea of taking CO2 actively out of the atmosphere, and then doing something with it.
Storing it underground, trying to convert it into something else that we can use, although that's a big challenge. The other type of geoengineering is the idea of changing the reflectivity of the planet. And that is a very different type of geoengineering than the one where you do CO2 extraction from the atmosphere.
And the reason this is very different is that if we think of CO2 and other greenhouse gases, let's just focus on CO2 as the main greenhouse gas. CO2 is the cause of the climate change effect, it's a greenhouse gas that results in this change in the energy balance that warms up the surface of the planet. If we take CO2 out of the atmosphere, then that actually addresses the cause of the problem.
On the other hand, if we change the reflectivity of the planet to whatever method we want to use, we change the amount of sunlight reaching the surface of the planet thus changing the temperature in a somewhat simplified portrayal of this.
And thus it actually doesn't change the amount of greenhouse gases. And thus it doesn't address the underlying cause of the climate change we're dealing with right now. Both of these are called geoengineering because they're active intervention by humans in this system intentionally trying to change what is currently in the earth system. The fundamental message that can’t be coming out wrong is that geoengineering is not a solution to the problem. It can only treat symptoms and I think it’s really important that people understand that part. It can never solve the actual climate problem itself.
Colleen: So describe different types of geoengineering
Frank: Right, so for the CO2, we're trying to get CO2 out of the atmosphere you can do this via chemical means where you extract CO2 out of the atmosphere itself, and then convert it into a chemical, and then store it somewhere. Or you can take CO2 extract it, try to store it as highly pressurized CO2 say in old gas and oil drilling wells. People have also suggested using the ocean and putting additional iron which is a fertilizer for the ocean, into the ocean hence increasing the biological productivity of the ocean. So the idea then would be that they use up more CO2 because plants use up CO2. And there's a variety of other methods as well.
And then the methods for changing the reflectivity of the planet, there's a whole variety of methods people have suggested for example putting mirrors into space. That's a very challenging idea where you reflect the sunlight back. There's the idea of putting particulate matter into the stratosphere, small particles below one micron are quite small.
Put them into the stratosphere which means about 20 kilometers above us and those reflect sunlight back into space. You can also try to change the reflectivity of clouds.
Colleen: So I just have to say this, this sounds almost like, a science fiction movie, where you're creating a weather machine, and you're going to change the planet. It sounds scary to me.
Frank: Indeed, it sounds very scary, and in some ways quite often people when they hear about this also immediately think about ideas like terraforming and such things. So it really is in many ways sounds like a science fiction idea. One of the really big cases of hubris is to say, "I'm gonna do this and I know exactly what's gonna happen." No matter how much research we do, I don't think we'll get to a point where we really can predict exactly with 100% confidence what's going to happen.
Colleen: Let's talk about the ocean idea for a minute where you're seeding the ocean. How do you control something like that? What if you seed the ocean, and then all of a sudden you've got a large scale mess on your hands?
Frank: That's correct, and this idea of fertilizing of the ocean with iron is very controversial exactly for that reason. Because in that case, you're really actively interfering in an ecosystem. And so that really is something that has to be even thought about with much care and what the impacts on this ecosystem. At the same time, it's also controversial to what degree this actually will be effective. You fertilize the ocean, you initially get more CO2 to go into the ocean, but in the end, does it have carbon. As with all these questions when you take CO2 out of the atmosphere the question is how long and where does it actually go?
For how long... is this a net uptake of carbon you know, that goes out of the atmosphere? You know, how long will this carbon stay in that? Does it really go in there? In the end, is the limitation really in the iron, is there something going on? There's a lot of open questions. Fundamentally there the question is how well do we understand ocean ecosystems?
Colleen: So let's talk about solar geoengineering. What do you think some of the risks would be in reflecting the sun away from the earth and back into the atmosphere?
Frank: I think there are two types of risks which are obviously related. One, of course, is that if you're doing that by actively putting something into the environment, actively changing the environment, there's sort of this first order effect. What is the impact of me putting a substance somewhere where it was not at all, or it was in much smaller amounts? And that can have a number of impacts of course. Then there's also the question of what happens by just reducing the amount of sunlight that reaches Earth? Which it's a sort of a secondary effect, it doesn't mean what is happening right where I'm perturbing it's a question of what happens to the overall Earth climate system.
So these are two impacts if you start lowering the earth temperature that has impact on the hydrological cycle. One thing where it gets very complicated is when people talk about these geoengineering types and impacts, what scenarios are we comparing to each other? And if I may I wanna give an example where we have volcanic eruptions, which in a sense have been natural experiments for this idea of stratospheric geoengineering.
So what happens after...after Mount Pinatubo eruption what happened is injected a lot of sulfur into the stratosphere, that turns into sulfuric acid, that turns into little particles, those particles reflect back sunlight. That is very similar to what we want to do with stratospheric geoengineering. And what one can see as a result is that, the temperatures went down on the earth surface on the troposphere. Which makes sense, there's less sunlight coming down to the surface, it gets cooler, it's like a little sun shade.
But we also know that there were a number of side effects. One of the side effects is that you had a destruction of stratospheric ozone, which protects us from UV radiation. There was also an increase in the temperature of the stratosphere where this aerosol was present. And I can talk about those impacts as well. So you're now changing two things already in the stratosphere, you have to direct effects, ozone, and temperature that you're changing. Each of those will have a number of downstream consequences.
Colleen: With the volcano, example...it happened for a specific short period of time. When you're talking about solar geoengineering, you're talking about putting particles up there and keeping that happening for a long time because we've got the situation on the planet where we've got way too much carbon dioxide, and we have to get rid of it. There's sort of a catch 22?
Frank: I totally agree. So one perspective on this is if we don't start cutting CO2 emissions quickly and drastically then the stratospheric geoengineering really is not a good idea because you can imagine we can keep on increasing CO2 emissions.
We have to put more and more aerosol on the stratosphere and this just becomes at some point like this runaway...I mean you'd have to do this for infinity. So that really can't be the scenario. And I also wanna say that we don't know enough about the science of stratospheric geoengineering to even say that one could do this at this point.
So fundamentally, for anything within this context the reduction of CO2 emissions and other greenhouse gases, has to be sent out in front. If that doesn't occur, you know, there's only limited utility in doing research or thinking about solar geoengineering. Right, so one of the analogies I have for this is that we have a cause of the problem, and that's CO2 and greenhouse gases. Those are changing our climate. And probably going to be changing the climate in a very dramatic way, that's gonna impact our children, and our grandchildren and a huge part of humanity who really are not at fault for this what happens. So we have to do this first.
Solar geoengineering addresses only a symptom, and only some symptoms. It can address perhaps global temperatures, for example, right. And the analogy I like to use for this is to compare the use of solar geoengineering with the use of painkillers.
All they really do is address a symptom that we have in our body. And that of course, as a result, it doesn't fix the problem. And for example, I have herniated discs in my neck, and when I get pain from that, I sometimes take painkillers. Although lately it's become much better and I don't have to. And when I use these painkillers, it doesn't hurt as much. Well, that's good because pain is suffering. But at the same time, because I don't notice the pain, I may actually have behaviors I shouldn't be doing because I actually don't notice the pain. So things that make my neck worse, I know I shouldn't be doing. That pain is a reminder don't be doing this, so when that pain is gone it's not there. For the climate question, the problem is if we lessen the suffering and pain then perhaps people will not reduce CO2 emissions because they're like "Well you know, it seems okay so let's do it later, let's kind of deal with this later." And that of course, cannot happen. That would be a horrible outcome.
I think that is one of the concerns with solar geoengineering is that it will make people complacent, because to some degree that is human nature.
Colleen: So let's say we do this in a more reasonable way, we make strong reduction in carbon dioxide. But maybe a little solar geoengineering would help. What happens in a scenario like that?
Frank: There are still numerous risks that we don't understand well enough for solar geoengineering and specifically stratospheric solar geoengineering. There are again these direct risks. Like with the painkillers, you put fundamentally a toxic substance into your body, of course that has side effects
Changing the temperature of the stratosphere which will, in turn, change the way the temperature moves. The same way that if you have a pot of water on the stove and you start turning up the heat, you can see how the circulation of the water changes, that is going to happen to the stratosphere when you change the temperature of the stratosphere. If I put more energy in a certain place, it will change that. That will have a whole number of downstream consequences coupling down to the troposphere where we live.
There's also the fact that whatever you're gonna put in the stratosphere, will come back down. And so one has to think very carefully what are the impacts of these materials. And so for the sulfuric acid geoengineering, we're talking about millions of tons per year that would probably be needed in the end. This is a significant amount, it's not as much as we're putting into the troposphere at the moment with pollution, but still.
Another problem which I think is not that likely, but could have very large consequences is something that I like to compare with the withdrawal symptoms. If you suddenly stop the solar geoengineering, these particles live for two to five years in the stratosphere.
So if you suddenly stop, your earth system is gonna in essence, bounce back to where it would have been without solar geoengineering in a very short amount of time. And that means that one of the things you would consider using solar geoengineering for to reduce the rate of change, that temperatures don't rise as quickly, or any climate impact what it may be. Suddenly, you're making that rate of change even faster than if you had never done solar geoengineering. There are studies that show that that can have very significant impact on ecosystems, on humans, all kinds of things.
Colleen: So Frank, tell me about some of the work that you are doing. You are working on SCOPEX?
Frank: Right and SCOPEX, stands for Stratospheric Controlled Perturbation Experiment. So what this means...to make clear what that means is that this is an experiment where the plan would be to inject a very small amount of material into the stratosphere. So let's first make clear again the stratosphere this experiment be at about 20 kilometers above the earth's surface. So the atmosphere in that area split into two parts of the troposphere where we live, and the stratosphere that's sort of high above.
The stratosphere is where the protective ozone layer is, there's lots of ozone there, but we don't directly inhale that. So it's not a pollutant. It protects us from UV radiation. And the idea would be to put a very small amount say something like 100 grams to one kilogram of material into the stratosphere, perturbing the natural state of that stratosphere on a very small scale, say on a few kilometers. And to start seeing what the impact of this perturbation is on that local atmosphere.
And the amount of particulate matter we're putting into the stratosphere this 100 grams to one kilogram, is less than you put into the atmosphere on an average airplane flight. So what we do is initially, we would distribute this aerosol over say a kilometer length in the stratosphere, would make a plume that is you know, a few hundred meters in diameter end to end and a kilometer long. And then we would study this. Over time, and...so it is more concentrated than what would you get out of an airplane plume initially for the particles. However, this will disperse over time, so this aerosol on the stratosphere will slowly sort of disperse and get so spread out that you won't even able to find an individual one of those over time.
So it will get diluted over time, but the impact again will be very small because of the very small amount that is used. In fact, these balloons that are used all the time for stratospheric experiments for astronomy, for other studies in the stratosphere, for all kinds of studies, they actually have ballast on them. And to control elevation they actually release this ballast. And the amount of ballast they typically release is much more into the stratosphere which gets dumped out there, is much more than we're putting in as material that we actually want to study.
Colleen: Tell me a little bit about the mechanics of it, how does it work? How do you get the balloon up there? How big is the balloon?
Frank: Right, so this balloon is a special stratospheric science balloon so it's very different from the balloons one may be used to, even hot air balloons. It's significantly larger than that. These stratospheric balloons that go up to even a higher altitude say 30 kilometers, they are filled with helium to give them buoyancy and carry them up. On the ground, they're not quite as big, but as they go up, they expand. And these ones that go really high in the stratosphere, 30 kilometers, in the end, they're roughly the size of a football field, so these are big balloons.
So the balloons are very big, they're filled with helium to bring them up there. And then below that, you typically have something that we call something like a gondola that is sort of dangling below there in a way very much like a hot air balloon. There's something dangling below, where the scientific equipment is, and that is used to do the scientific experiments. So what we need to do is we have propellers on this gondola, so that we can actively move the balloons with the atmosphere. And while it's doing that, we sort of disperse the small amount of particles, and the first particles we may use may be calcium carbonate, limestone. And so as you're doing this, the propellers move and also mix up this plume a little bit, of particles that you're making out so that you get a well-mixed plume. And then you sort of fly along for a kilometer or so, and then with the propellers, the idea is that you turn around the balloon and fly back through this plume.
And you can see as you go back in the plume, you're going...the first part you made of the plume has had much more time to react in the stratosphere than the last part. And as we go back, we can kind of see exactly how this air mass has evolved over time. And that is sort of a cartoon image of how the experiment would work.
Colleen: What does it physically look like? Something that examines the particulate matter.
Frank: So what we have...for example, one instrument that looks at the particulate matter that we also use to tell us where the plume is. When we have to see our balloon back, the question is how do we find this? This is still a very thin plume. You can't see it by eye. So what we actually have is an instrument that is a laser that sends out little light pulses, and these light pulses travel, and when they hit something some of the light gets reflected back.
So we scan this laser and then we know where it's pointing, and then we see a return signal from an aerosol, and we say, "Oh, the aerosol is at that angle is where the plume is." And in addition, as we know the speed of light by measuring how long it takes for that light to get back to us, we actually know how far away we have.
Colleen: So you can create a map essentially?
Frank: That's right, we can sort of try to create a map of this aerosol plume with this instrument that's called a lidar. But it's fundamentally just a pulsed laser that is used for this. And then we also have other instruments that what they do is they don't send something out, they actually take some of the air. And then we measure in the instrument how much for example of ozone there is. So there's a whole array of different types of instruments that do very different things.
Colleen: So you have to get those instruments back to analyze, or is there like computer? Are you getting data coming back from the stratosphere?
Frank: So the idea...I wanna make clear that as this experiment hasn’t happened, this is the plan. The plan is that most of the instruments are measuring as they are flying. But also some of it will be sent down directly to the ground, so that we actually, for example, can know on the ground where is my plume. So that we can make sure this balloon is actually going back to this plume. And then there may be one instrument that actually collects the particles, and then brings them back down to analyze them later in the lab for example, with an electron microscope or some other method. Because then we can see has the morphology of the particles changed, have they sort of changed out a shape by being in the stratosphere? Have they changed the chemistry on the outside? So that's another type of instrument, that is one that would collect it, bring it back down and it would be analyzed in the lab.
Colleen: Do you ever think that you're opening a Pandora's box by starting this experimentation?
Frank: Yes, I regularly think about this. And this was a long internal debate I had with myself before I actually decided to get into this research. Is pursuing this research which from a purely technological perspective, scientific perspective I think is very well worth doing, and I think in fact has to be done. Is this a Pandora's box that in other dimensions may result in all kinds of unwanted effects, where people will try to use this research in ways that I don't agree with, and that actually would be detrimental to the overall effort? My overall goal is to better understand the risks, some of the risks, but will the experiment itself be used, portrayed in ways that actually make the gain you get from that, and scientific insight on this problem, less than the damage it could do? And I have come to the conclusion that I believe it is worth doing this research. But it is something that is my opinion, and there are a number of people who disagree with that.
The one thing I'll say is that I think this idea is out there about the solar geoengineering. I think research on this will be happening, and so I think my goal is that I think we should try to get knowledge as soon as possible. But at the same time, my goal also is to try and do this research in a way that sort of portrays the best ways of trying to do such research. The best thing against it being abused in some way, is as many people as possible really having some understanding of what solar geoengineering is and what it's not. But this is quite a concerning question.
If you continue burning fossil fuels, you know, then we're going down the wrong way." Fundamentally, whenever you think about solar geoengineering, you need to have emissions reductions and mitigation front and center.
Colleen: Well, Frank, thanks, for joining me on the podcast. This has been a really interesting conversation.
Frank: Thank you very much for having me, pleasure to be here, thanks a lot.
Note on recent news: Shreya Durvasula
Editing: Omari Spears
Music: Brian Middleton
Research and writing: Pamela Worth
Executive producer: Rich Hayes
Host: Colleen MacDonald