METTA SPENCER: Hi, Gwynne. Tell me about your book.

GWYNNE DYER: Okay, it’s called Intervention Earth, and it’s out in Canada now. It’s coming out in England next month, Australia, New Zealand, on staggered publication. It’s basically a survey of what we are doing to deal with global warming and what the timelines are. Lots of good ideas are out there, but when will they be scaled up and start having a real impact on the planet?

About 15 or 20 years ago, many people realized that we do have a problem here and scientists and engineers and inventors started thinking about ways of dealing with it. It took a while but it is happening now. Every month, there’s something coming out – all good ideas – but there was a 20-year delay. For example, we’ve been discussing direct air capture for 20 years and only now the first plant is being built in Texas and in Louisiana. Twenty years! Part of it is politics. Think of who is in power in the United States for most of those 20 years.

SPENCER: Half of the problem is the timing. The other half is: What really will work or what is affordable in terms of the amount of energy it will take to do it?

DYER: I agree.

SPENCER: And direct air capture is one of the question marks. You’ve got to convince me that it’s not going to require more energy than it’s worth.

DYER: You’re only going to convince people that it is or is not worth doing by trying to do it. But the problem is that all of these good ideas have to be rolled out at scale in the end, to make an impact. How long will that take? The most successful way of getting out of fossil fuels is solar capture. Now solar panels have scaled up. They’re everywhere and taking a significant bite out of the problem. But that took 20 years. We want to know when we can see real effects from every available or imagined technique.

Unfortunately, the ones that are starting to come out now are not going to be at scale in five years. They might be in 10 or 15 years. Apply that against the fact that we are certainly going to have increased past 1.5 degrees Celsius by 2030. Frankly, we’re past it right now, but we may drop down a bit after El Nino passes. We won’t drop back down to where we were before. I’d be very surprised if we were below 1.4 a year from now, which means that there isn’t much time for these projects to go to scale and stop the inexorable move towards plus two degrees. So, you have to make that argument – and that’s what I tried to do in the book. I say, yeah, all these good ideas, put your shoulder behind them; work on developing them as fast as you can; figure out which ones are most cost-effective, all that stuff. But you can see that’s not going to solve our problems in 2030 or 2035. Therefore, you have to look at geoengineering. You don’t know the details yet, but you know that you’re going to need that. Otherwise, you are going to bust through all the barriers.

SPENCER: Hold on. I thought you were going to say that even the geoengineering ones aren’t going to be ready that quick. Last year, I did a series of shows with the Canadian Pugwash Group. I picked four modes of solving global warming that I thought could be started within five years. The question is: Which of the geoengineering ones can we get going quickly?

DYER: Very good question. Obviously, that’s the other question you have to ask. But you have to take your audience to the point in the argument where they agree that we need to consider geoengineering. And then you go through the process of okay, what’s cost effective? What’s available quickly? What are the risks – all that stuff, but they’re not even going to listen to that until you’ve persuaded them they have to worry about geoengineering working, because nothing else is going to.

So, you do have to work your way through the weeds and talk about why solar power is brilliant. And what it has succeeded in doing over the past 10 years is prevent the proportion of fossil fuel power in the mix globally from getting worse. It hasn’t actually cut into that 80% share of power coming from fossil sources. What it’s done is, the non-fossil has managed to keep up with the rate of growth in the fossil and kept us at 20% non-fossil fuel. We’ve got to do better than that, obviously, but it ain’t gonna happen overnight. I’m talking about the share of fossil fuel, which remains at 80 percent. During the last 15 years fossil fuels have grown and non-fossil power has also grown, and it is managing to grow at the same rate as the economies expand and therefore it means we’re not losing ground, but that’s not enough.

SPENCER: When I talked to Sean Fitzgerald, I mentioned that the use of fossil fuel energy is still increasing in absolute numbers and not even going down. And he said yes, but the rate at which it’s increasing is decreasing. So, it’s flattening, plateauing;

DYER: That’s true. But the point is, we do have the technologies, but we don’t have quite the political will yet. Within a year or two, we may see the share of fossil power in the mix drop to 80%, or even 79%. That’s the point: We are making progress, but it’s not fast. And you are going to hit levels of carbon dioxide and methane in the atmosphere that will drive you over two degrees sometime in the 2030s. It could be the early 2030s. There’s a lot of false optimism out there because people don’t want to talk about what happens and what to do about it if we actually do go to two.

I think the odds are even that we will go to two in the 2030s unless we get some geoengineering going. But you have to make that argument and then halfway through the book, you start to talk about geoengineering – which of those techniques will be most effective, and all that good stuff. Particularly for people who haven’t taken it aboard and who have been told repeatedly that geoengineering is dangerous.

SPENCER: Yeah. But, well, it could be. That’s the problem.

DYER: It could be. I was talking to David Keith the other day, who I think most people watching this will know. And he said, “Listen, the research is done. We could do it tomorrow.” We were talking about SAI – Stratospheric Aerosol Injection. He said, “We could do it tomorrow.” And I actually think that’s true, because volcanoes have tested it for us.

SPENCER: You’re right but, by the way, Harvard has just killed their project on SAI.

DYER: That’s why he moved to University of Chicago. I think. But he had already made the jump to go to Chicago and University of Chicago is giving him far more resources than Harvard ever did. So, this is not necessarily a bad thing. But the work is still being done by under 100 people.

SPENCER: You mean the SAI work in general – the number of people working on SAI?

DYER: Yes, I would say the number of people who are working full time on that would not number more than 100.

SPENCER: Well, frankly, there are more promising options. I would say Marine Cloud Brightening has a lot more promise. I would say Iron Salt Aerosol has a lot more promise. I would say even Cirrus Cloud Thinning has a lot more promise and maybe Ocean Iron Fertilization.

DYER: Yeah, those are the ones we should be looking at. But just to get people to look at them, you’ve got to persuade them that they don’t have other easier options.

Easier in the sense of less frightening and easier politically. So, we have the geoengineering options – but none of them have been tested outdoors so we are virgins discussing sex. I agree with you that Marine Cloud Brightening is the most promising and the least threatening. We can turn it off right away if there’s a problem.

SPENCER: It’s not ready.

DYER: I know it’s not ready. Nothing that we’re going to discuss this morning is ready.

SPENCER: Well, I think some things are. Like Iron Salt Aerosol. I think they could do that next year.

DYER: I know some can come on line faster than other bits – but ready at scale? I think you’re looking at five years for anything. But that’s a political, not a technological, calculation.

SPENCER: Sure, because it’s going to take that long to get people on board. That’s why the challenge is to work on people as much on the technology. We’ve got to do both.

DYER: I couldn’t agree more. That’s what we’re doing, isn’t it? Right here, right now?

SPENCER: (Laughs) You and me, we’re a team!

DYER: So how do you go about that? There are strategies for getting people on board in terms of persuasion, in terms of publicity, in terms of getting it into the political debate, as well as the philosophical debate and the technological debate. But they are time consuming! For example, here in Canada, they’re still having a huge argument about carbon tax.

SPENCER: I know. They may even abolish a lot of it.

DYER: Well, I don’t know, but it is having an impact. Canada cannot apparently deal with its huge carbon guilt over Alberta Oil, so that at least was partly compensating. We really are the skunk at the dinner party. But within the next five years, you have to find a way of persuading the public. Now, nature will help you because it’s going to get worse. Jim Hanson was saying, watch out, this is going to be the year that we bust through 1.5 big-time. The jury’s still out on that. It’s only March as we’re talking.

SPENCER: Yeah, but February was the hottest February on record in the world.

DYER: January was the hottest January, December was hottest. We have nine months in a row that were the hottest month ever. So, we’re past 1.5 on a monthly basis. We’ve got nine months now past 1.5. The technical definition is the average of the path of the 20 years – sort of 10 years ahead and 10 years behind. If we’re up past 1.5 on that 20-year average, then we’re past 1.5.

Sorry, guys, that’s the wrong way of looking at it because you’re not working out an average that’s stable. You’re talking about a moving target. And when it goes through 1.5, it doesn’t go back to averaging out. It just goes up! There’s a debate now in the scientific world about whether that is the right way of defining 1.5. Five years late. We are in deep trouble. We will know more about how deep the trouble is and how much faster than we expected by the end of this year. Right now, we see one degree higher ocean surface temperature than any of the models can explain.

We need a way of countering the feedbacks at tipping points that go runaway. All of our calculations are on linear growth warming. But we know damn well that there will be nonlinear jumps in warming if we cross certain thresholds. This may be the first such threshold, not one of the ones that we were predicting. A sudden one-degree anomaly in sea surface temperature was not on the list of 20 expected bad sudden jumps, but it could turn out to be one of them. Maybe we crossed some tipping point that we didn’t know was there and it’s driving sea surface temperature up. You’ve got to be prepared for those things. If this year turns out to be as bad as last year, then just look out the window to persuade people to take geoengineering seriously. We do have an ally. It’s an unwelcome ally, but allies are often unwelcome.

SPENCER: Yes, if people look out the window and see a forest fire coming at them, those are very persuasive events.

DYER: They are. But think about what happened in British Columbia or Alberta – I mean, Fort McMurray and all. Look at how it’s being reported! People mention global warming occasionally but there is no drumbeat saying: “This caused by a problem you’re not paying attention to. Fighting fires, digging fire breaks is no answer. You won’t stop it that way.” That needs to be emphasized every time it happens. Somebody’s got to do that. Who’s it going to be? You, me? Who else?

SPENCER: Not the newspapers, not the networks.

DYER: Yeah, so a lot of work to be done.

SPENCER: Indeed. Now, you went around to talk to experts, and you came up with your own ideas of which geoengineering technologies are promising – which ones are possibly cost effective, feasible, and can be done quickly. So, I’d like to compare what you would bet on to my own notions, which are always in flux. I change my mind every other day.

DYER: We all do because there’s a lot of uncertainty. Anyway, the one that I would be most confident in deploying the day after tomorrow (if there were any hardware out there to deploy) would be Marine Cloud Brightening. It can’t go very wrong, because you can turn it off overnight.

SPENCER: Agreed. The persuasive thing is, how quickly could you change your mind if something really bad happened? And if we could stop the whole thing within a week, I think people are willing to say “Okay, let’s give it a try.”

DYER: Right. Second, in terms of operating at scale, I’m afraid to me it’s SAI –injecting aerosols into the atmosphere. Again, you can’t turn it off right away. But you can turn it off.

SPENCER: It takes a couple of years before the stuff starts settling to Earth.

DYER: Well, frankly, most of it falls out in a year. You’re down to very low levels in 12 months It will be more than halved within a year. And consider the Pinatubo volcano, which put about 17 million tonnes of sulphur dioxide into the atmosphere.

SPENCER: With what effect?

DYER: Sulfur dioxide actually is a gas, and it reflected a good deal of incoming sunlight and we had a global cooling of almost one-degree Celsius, tapering off over the next two years. So yes, you can cool the climate. No, you don’t need a volcano to do it. You could just go buy some sulphur dioxide, which could be captured instead of put out as industrial pollution.

And nobody died! There were no grave effects in having 17 million tonnes of this stuff in the stratosphere for two years. We would not be putting that much up unless we kept doing it for half a century. But the idea is to do what they call ‘peak shaving’ – don’t let the temperature go above a certain area, while you frantically get the carbon dioxide out of the air and can then stop geoengineering. So, 17 is a number way beyond what we would be doing with SAI. One million tonnes would be more like it.

You’d start even smaller than that and build up over a few years, watching carefully to make sure there are no surprises. But there shouldn’t be, because volcanoes do this at a much larger scale and very abruptly. So, it’s not exactly a Get-Out-of Jail-Free card, but if you need it, you do have a quick solution.

The slow solution, the one that works permanently, is getting rid of emissions and not putting any more out. In the late 1990s or early zeros, people realized that getting rid of all the emissions in a world that is 80% powered by fossil fuels is going to take a while. But they had no idea how long that was going to be because we haven’t gotten rid of any of it yet. But they did understand you needed a fall back. So, from the late ‘90s of the last century, a number of people were investigating the implications of doing what we know volcanoes do. There were early open-air experiments with a large balloon and a 23-kilometer pipe.

SPENCER: Like a drinking straw going into the sky!

DYER: Right. Called the SPICE program. I’ve talked to some people who are involved in it. They never intended to do it. They were just investigating the technology mathematically. They thought they’d boost a couple of bathtubs full and spill it over a field in Norfolk, to prove that they’d done a real experiment, but it was mostly mathematical studies.

But some people opposed even thinking about it because at that time the assumption was that cutting emissions was going to be easy. We’re going to switch 80% of the world’s energy use over to non-fossil fuels in 10 or 20 years. So, don’t distract us with other things that would just slow the one technique that we know is permanent and works.

The problem is, that view has persisted although the process never even got started. We have never cut emissions. A few years, our emissions dropped a bit, but they’re always going up because it’s cumulative. In 1990, we were at about 350 parts per million of carbon dioxide in the atmosphere. We are now at 425 parts per million. After 30 years of trying to do it, we have lost that much ground. So, it’s unrealistic at this point to argue that we must not experiment with ways that keep the temperature from running completely out of control because any experiments in SAI would distract from getting rid of the carbon dioxide. You could convince me of that if you’re getting rid of a lot of the emissions, but you haven’t even got started in 30 years. So don’t tell me we shouldn’t look for fallback positions. It’s 30 years later and you’ve used up your ‘thinking-about-it’ time.

SAI has occupied the most attention because it’s the one that has been pre-tested by nature. There are other gases or particles that you could put in the air that would also reflect sunlight, but the focus is on sulphur dioxide because we know it works and we know it doesn’t kill people.

There has been an issue about ozone holes possibly not shrinking so fast. That’s one of the arguments against it. Sulphur dioxide does not directly kill ozone. It kind of operates as a catalyst by which chlorofluorocarbons destroy the ozone, but they destroy it faster if there’s a lot of sulphur dioxide in the air over the poles.

SPENCER: I didn’t know that.

DYER: We dealt with the ozone hole 40 years ago by cutting all of those CFC emissions. But the ozone hole over the Arctic never grew at all, and the ozone hole over the Antarctic began to shrink. And it’s still shrinking. The amount of ozone destroyed by Mount Pinatubo was not inconsiderable, but if consider the sulphur dioxide volumes that we might inject over the Antarctic to hold the temperature down, it would probably slow the healing, but the ozone hole there wouldn’t start expanding again. For example, whereas we thought that the hole might be completely closed by the 2040s, maybe it would be in the 2060s. But it’s not over any inhabited areas even now and not even a lot of animals are at risk from the solar radiation that the ozone hole let’s in. So, I don’t think it’s a big issue.

The other issue you hear a lot about putting sulphur dioxide in the atmosphere is that it moves the rainfall around and there will always be aggrieved parties who lost their rainfall. Actually, that problem was detected in the very early days by people doing mathematical studies. Nobody’s putting stuff up in the air; it hasn’t been done at all. But in a model, when they simulated putting up significant amounts of sulphur dioxide into the air, they found that it did move the Intertropical Convergence Zone, which is about 500 miles north and south of the equator. It used to be called the ‘doldrums’ in the sailing days. It would move that up or down.

SPENCER: Do you mean expand the band or just move it?

DYER: Move it in latitude. This is particularly important for West Africa because the West African monsoon is part of the doldrums that we used to talk about in the Atlantic Ocean– very rainy area with almost no wind. Over land, it delivers a lot of rainfall, which is why there is a band called The Sahel in West Africa, which actually is in the middle of the Sahara, but gets rainfall from that band of weather. It wouldn’t disappear, but it would move south if you did a lot of geoengineering with solar, SAI. Because, if you put the sulphur dioxide up there, you will also move that band with the rainfall south. Several countries in the Sahel depend entirely on that rainfall for their agriculture. If suddenly the rain moves south, instead of falling in southern Niger and Chad and that band of countries in the Sahel, it would fall on northern Ghana, northern Nigeria, which have enough rainfall already. And the people up north would be in desert and starving.

That was the image we were given back then. So, what did they do? They went back and did their mathematics. The consensus is that if you try to counter the full warming for the year by loading all that sulphur dioxide into the atmosphere, yeah, you are going to move that band and kill off agriculture in several West African countries. And that’s definitely not a nice thing to do. But if you only counter half the warming, the amount of sulphur dioxide you’re putting up there will cause the normal amount of rainfall in the normal places. So no, you can’t cancel all the warming, but you can cancel half of it. Is cancelling half of it good? Yes!

SPENCER: But can’t you do half of it that way and then go use another technology?

DYER: Exactly. Then you can start with things like Marine Cloud Brightening, as opposed to the stratospheric stuff. Marine Cloud Brightening is done right down on the ocean surface in what they call the ‘boundary layer.’ You mustn’t imagine people spraying stuff up into the atmosphere to try to get it up into the clouds. You just let convection do that. You use very specialized nozzles that produce literally trillions of tiny bubbles of water a second. But you can get a trillion out of a bucket of water onto the sea surface, or just above the sea surface, not very high. Tiny bubbles of water going through even tinier holes and being laid like a mat over the surface in the wake of the ship. About half of that will be lifted by the warming of the sun, drying out and leaving only little morsels of salt from the salt water. Then the bubbles dry into particles of salt, which are lifted into low-lying cloud layers. I’ve been in the navy and have been at sea in the tropics. There, you’re under a cloud almost all the time. It’s a layer of what they call ‘marine stratocumulus clouds’ – a layer no more than 200 meters above sea level and so thin that you can usually see the sun through it. But if you thicken it up a little, you’ll still be able to see the sun through it, but it will be reflecting much more sunlight. So, in terms of holding temperature down, Marine Cloud Brightening is basically thickening up marine clouds to reflect more sunlight using vessels with little sprayers. They’re satellite -controlled and unmanned.

SPENCER: We’re going up put a photo of one on the back cover of Peace Magazine. I interviewed Daniel Harrison, who’s trying to save the Great Barrier Reef, He has a boat where you can see the spray coming out the back.

DYER: Excellent. By the way, while it works best in this low-lying layer of marine stratocumulus cloud, there’s a Norwegian who did experiments with data rather than actually going out in the boat. She concluded that you could do it over any part of the ocean, including parts that don’t have cloud. You will get less cooling in areas without cloud, but even there the invisible moisture will work. When the little morsels of salt reach cloud level, they’re the nucleus around which water condenses into droplets. That’s the whole point, get the little bits of salt up there.

SPENCER: Yes and we should say it makes it whiter.

DYER: Yeah, the cloud becomes whiter, it reflects more sunlight. And these droplets, without being part of a cloud, also reflect sunlight so you get 30 to 50% of the effect when there’s no cloud around at all.
But none of this has been tried in open air because of this grim determination not to distract us from failing to do what we are, in fact failing to do anyway. Stephen Salter was the guy who did this research. He just died. I saw him as recently as last year and I hope his work is picked up by somebody because he was doing some very important …

SPENCER: He has left money for it to continue. He has a workshop.

DYER: I know about the workshop. Some former students of his invited him to work in the building that they had bought. So, the work will continue.

SPENCER: The problem is, as he put it to me, the nozzle isn’t good enough yet. If you don’t have the right size of spray, it won’t work or could even have negative effects.

DYER: That’s right. But this is an engineering task and Stephens Salter was an engineer. How he got involved in this was that the guy who originated the idea phoned and asked whether he could make a nozzle.

SPENCER: Latham.

DYER: He said, “Yes, of course I can.“ He still hadn’t succeeded when he died. But he was definitely close, he thought. Anyway, the great virtue is that it’s stoppable. If anything goes wrong, you just stop spraying and the side effects stop within a day or so. So Marine Cloud Brightening and Stratospheric Aerosol Injection are the two big tools. There will be others.

SPENCER: I know about a dozen others and I’ll be interested in which one you think is number three.

DYER: Okay, this is about one guy with an interesting idea. It’s important because we’re already in the danger zone and with every temperature increase, the risk of something really bad happening also goes up. The climate changes in sudden lurches and we are close to some of those lurches, but we don’t know enough. I know people who think it’s happening right now, and we’ll know by probably September whether we are in the middle of that kind of lurch upwards right now. Besides Stratospheric Aerosol injection and Marine Cloud Brightening, there are other means, but you couldn’t get any of them up and running in six months. Most of them would take six years, even with a crash program.

But I ran across this fellow called Bob Nelson, who is a retired engineer with the Caltech group, the Jet Propulsion Lab, JPL, who have done extraordinary work over 40 or 50 years – including atmospheres on other planets, which is what he used to do. He showed up at a semi-annual conference of geoengineers and was treated with disrespect, frankly. This is a man who was a senior research scientist at the JPL for 40 years. Come on! He’s not a nut case. And the precise problem he wanted to address was: What if we suddenly needed to do this now?

SPENCER: Do SAI or what?

DYER: Do an atmospheric intervention. We know you’re going to have to build ships to do Marine Cloud Brightening and design the nozzles. You’ll have to build aircraft to get up into the stratosphere to spray the sulphur dioxide if you’re going to do…

SPENCER: Can’t they do it with existing airplanes?

DYER: No. They tend to express altitudes still in feet and 60,000 or 65,000 feet is about the minimum at the equator to get the sulphur dioxide into the stratosphere. Spy planes fly that high. Enormous wings, spindly little bodies, very specialized engines, because the air is very thin up there. Nobody has built a dump truck that could carry up sulphur dioxide to that altitude. It’s not technically impossible; it just hasn’t been done and airplane development takes time.
p<>. I do know one scientist at the National Center for Atmospheric Research in Boulder, Colorado. She’s a German scientist who thought that maybe you could use a plane that’s able to get up to 55,000 feet. We’ve got lots of them. Private jets tend to fly at that altitude to get out of the way of airliners. But maybe we could then put the sulphur dioxide and little particles of soot that would warm up, rise, and carry the sulphur dioxide with it the last 10 or 15,000 feet. She’s not sure that would work. But here’s Bob Nelson, whose whole work was about reflectivity on planetary surfaces at JPL.

SPENCER: Reflectivity like painting roads white?

DYER: Well, if you’ve ever driven on a road that’s paved white, you need sunglasses in the dark. But his problem was with existing technology that we may need now. He thought, well, table salt has about the same reflective qualities as sulphur dioxide. You’re trying to bounce sunlight back into space. You can’t put table salt into the stratosphere because half of sodium chloride is chlorine – precisely the element that eats up the ozone. But he thought, you can put it in the troposphere down here where we breathe. We put it on food. It’s not a dangerous substance. So, he thought, if you needed to use existing technology next week, you could just get a bunch of 747 freighters and sprinkle table salt at about 30 or 40,000 feet. That would give you enough reflection to hold some temperature down. He got some people to do studies on it. He reckoned that about 300 of the 747 jumbo freighter version about four times a year spreading table salt into the atmosphere would reflect enough to give you one degree of cooling.

Who knows, but it’s nice to have something in your back pocket that might work. His task is to get the answer to this because he hadn’t got through to the right people. The question is, can you make the salt particles small enough that they don’t immediately fall out of the air? Table salt falls to the floor. It’s too heavy.

SPENCER: Just grind it.

DYER: Yeah, but it must retain its reflected possibilities.

SPENCER: If you grind it too small it might not reflect?

DYER: That’s what you need to test. But not seven years of testing. It’s about three weeks, if you can get somebody to do it. The planes are there, the table salt is there. Look, I don’t know if this works.

SPENCER: Here’s something similar that I dismissed as implausible. But rice husks are white and they float. There’s a hell of a lot of it because when you polish all the rice in China and India, you’ve got a lot of husks. You might even cover all the oceans with floating white things that would reflect a lot of the light back into space. Game over. See if you can top that one.

DYER: Hugh Hunt at the Center for Climate Repair in Cambridge and an Indian scientific body cooperated in sprinkling rice husks in the Persian Gulf last year, but a huge storm came and sank at all. They were using the husks to carry a smorgasbord of things that would encourage algae to bloom in large quantities. A husk was just a little boat that they floated on. Algae start to eat all this stuff. Then, you get the bloom and huge amount of absorption of carbon dioxide, which may or may not sink to the bottom.

SPENCER: Right. Well, I notice you haven’t mentioned that usually it’s iron they want to sprinkle on the ocean. Tiny iron filings in certain areas of the ocean. Sometimes it’s potassium or other things that are scarce in a particular area. Iron is the main one. Without it, the phytoplankton don’t grow but, by sprinkling it, you can replenish and bloom your phytoplankton. It has a lot of effects. It exudes stuff that’s good for the clouds. It feeds fish and it captures co2 that can sink to the bottom of the ocean to be sequestered. I’m up for examining it. But you didn’t name it.

DYER: I’m in favor of examining it. It was in fashion 20 years ago, and a bunch of entrepreneurs made money and then folded their tents and went away. Nobody was able to prove that much carbon dioxide was being absorbed by these plankton blooms an whether it was eaten by fish, and whether it sank to the bottom.

SPENCER: I know of one person who actually did it – a guy named Russ George, whom the Haida Indians in BC hired to increase their haul of salmon. He did so, and it worked. The next year, they had a bumper crop of salmon. But the Canadian government said: You can’t do that again. Maybe they thought it just sounded like geoengineering.

DYER: It wasn’t geoengineering, it was just to encourage more fish. His idea was that plankton are fish food, so we’ll grow the plankton for that. He wasn’t measuring whether the carbon dioxide was being absorbed and sequestered. Maybe that’s a good way to encourage more fish but it’s not about climate.

There were scientists and entrepreneurs throwing carbon iron filings off the sterns of ships in large quantities. And there were algal blooms. But there was almost no scientific work done. That’s not really what most of them were there for. This was 20 years ago. Now, there is some reawakening interest in it, but the large questions remain. First, this is an extreme intervention in the ocean. You are changing the character of the population of living things in the ocean. Not just once a year like plankton blooms; you’re doing it a lot more. So, scientists would want a long, careful look at this before they encourage it. It might work. Lots of things need to be looked at.

But you got to get over the taboo. For example, David Keith is one of the earliest and most active investigators of Stratospheric Aerosol Injection. He had government permission to test the equipment. Sulfur dioxide-based gas in the air clumps if you’re moving fast when it comes out of the airplane. He was just using balloons with little propellers and had approval from the Swedish government. But a well-known environmental group went and told the Indigenous people in northern Sweden that this would be done at an altitude where their gods live and would disrupt the stability of nature, possibly the entire universe. So, the aboriginals said no, we don’t want this done. They had talked to Keith but the other lot got to them. It was all canceled and shut down. Then Harvard, where Keith was working, started moving to close down his whole geoengineering enterprise. I know David, but I haven’t asked him. I think that’s a main reason he’s just moved to the University of Chicago. It’s as easy to persuade Harvard professors as it is “Laplanders.”

SPENCER: I can’t disagree. But there is evidence that the more people know about geoengineering, the more favorable they are – at least to investigating, if not deploying it. We should check out a whole bunch of different things that can be called geoengineering. Even wacky notions. Salt. Rice husks. Everything. Let’s do it.

DYER: Yeah, exactly.

SPENCER: I hope your book does what I expect it to do. It’s going to make a big splash. I’ve only read a little of it so far, but I’ve been totally wowed. Wonderful to talk to you, Gwynne. I think I should let you go to the airport now.

DYER: Yes. Thank you very much, Metta.

SPENCER: It’s been wonderful. Bless you.