From "How to Cool the Planet: Geoengineering and the Audacious Quest to Fix Earth's Climate," by Jeff Goodell
Stephen Salter, age seventy-one, handed my son Milo, age eleven, two small jars of glass balls and said, "This is going to save the world."
We were in Salter's ofﬁce at the University of Edinburgh in Scotland. The ofﬁce looked as if it had been decorated by Jules Verne.
It was stuffed with dusty books, wires, nuts, bolts, brackets, and other mechanical debris. Salter is widely regarded as an engineering genius of the nineteenth-century variety -- a man who works not in digital bits and bytes, but in hard metals that obey the laws of physics. His most famous invention, known as Salter's Duck, is a wave energy machine that he built in the 1980s and that is still considered to be one of the most efﬁcient devices to extract energy from waves (although it has never been deployed on a commercial scale -- Salter blames the nuclear power industry in Britain for killing it). But he has also worked on robots, minesweepers, hovercraft, and ﬁghter planes. Just down the hall from his ofﬁce at the university is his metal shop, full of lathes and presses and other serious equipment. He prides himself on his ability to make things himself and happily repeats the story of how he was once dismissed by a white-shirted atomic engineer as "a greasy-ﬁngered mechanic." ("I took that as an enormous compliment," Salter told me.)
Milo took the two jars from Salter. He is a smart kid, but he clearly had no idea what to make of Salter's statement about the glass balls saving the world -- and frankly, neither did I. The two jars looked identical, except that the beads in one were darker than those in the other.
"How is that going to save the world?" I asked Salter.
He ignored me. "Take a close look at them," Salter said to Milo. He is a tall man with graying hair and a hawk nose. He was dressed in blue slacks and a blue Windbreaker. He has a reputation for being difﬁcult to work with, a man excessively attached to the perfection of his own ideas, but with Milo, he was patient and interested. It occurred to me that designing cloud-brightening devices and wave energy machines is not unlike playing with Legos: to be a great inventor, you need to see the world in a childlike way.
"What's the difference between them?" Salter asked.
"The beads in one jar are darker than the other," Milo replied accurately.
"Yes -- but why?"
"Because they are different colors."
"Ah, I thought you would say that. Actually, the beads are the same color. They are just a different size, so they reﬂect light differently. In the jar with the small beads, there are more beads, which have more surface area -- so they scatter more light, which makes them look lighter."
Milo nodded, processing the idea. "Okay . . . So how is this going to save the world?"
"Because we're going to use the same principle to brighten clouds, which will then reﬂect more sunlight, which will then help to cool off the planet." Salter nodded to a chair next to his supremely messy desk, motioning for Milo to sit down. "Let me show you what I've been working on."
I don't usually have the luxury of taking my family with me on work trips, but I had brought Milo and his twin sister, Georgia, with me to Edinburgh because I had to travel to the city for a small workshop on cloud brightening and the workshop happened to be on their eleventh birthday. What better place to celebrate your eleventh birthday than in the shadow of Edinburgh Castle? My mother came along, too, both for the adventure and to help with the children while I attended the workshop. The day after the meeting, when I mentioned that I was going to visit the lab of a scientist who was working on a cloud-brightening machine, Milo immediately asked, "Can I come?" (Georgia preferred to explore the city with her grandmother.) I was reluctant to agree, mostly because I had not met Salter before and didn't know how he'd respond to having an inquisitive kid around.
But when we met outside his lab at the university, Salter seemed delighted that I'd brought Milo with me. He asked Milo about his interests, and when Milo mentioned science, Salter made it clear that he thought of himself as ﬁrst and foremost an engineer: "Scientists are people who know more and more about less and less, while engineers have to know a little about a lot of things, and they have to learn it fast."
As we walked, I asked Salter about his background. He told us that he was born in South Africa in 1938 and lived there until he was seven years old, when his family moved to southeastern England. As a kid, he was always interested in making things -- especially model airplanes. When he was seventeen, he began an old-fashioned apprenticeship with an aircraft company on the Isle of Wight. ("My grandmother was very concerned about social status. She said, 'You won't be with actual workmen, will you?' But of course I was. And I was proud of it.") He worked as a ﬁtter, a toolmaker, and an instrumentation engineer. When he learned that some of the planes he was building were used for military purposes, however, he quit. He spent three years studying physics at Cambridge University, where he became interested in, among other things, artiﬁcial intelligence and robotics. In the early 1970s, he moved into mechanical engineering, especially wave energy, where his work is still considered revolutionary, even if it has never been commercially deployed.
In his ofﬁce, Salter pulled up an artist's rendering of one of his cloud-brightening boats on his computer screen. He told Milo that each boat would be about 150 feet long and weigh 300 tons. It was a trimaran, with three long, canoe-shaped hulls linked together for stability. Instead of sails, however, there were three long tubes ("They looked like toilet paper rolls," Milo told me later) with regularly spaced ribs on them. These tubes, which would be about sixty feet high, were Flettner rotors, which act like sails but are more efﬁcient. They would also work as smokestacks for tiny saltwater droplets that Salter planned to launch into the clouds.
I had seen the image of the vessel many times before -- it's a favorite of scientists who talk about geoengineering, as well as journalists who report on it, because it reeks of high-tech innovation. It projects very clearly the idea -- perhaps "fantasy" is a better word -- that the earth's climate might someday be controlled by devices that are as cool and well engineered as a Porsche. It made the big, kludgy machine that I'd seen in David Keith's lab seem like a primitive contraption. But, of course, Keith's machine actually existed. Salter's was only a drawing.
Milo was obviously taken with it, too. "Cool!"
"Do you notice one thing that the boat is missing?" Salter asked.
Milo looked for a moment. "Sailors."
"Exactly! The boats are unmanned. They will operate entirely by remote control."
This excited Milo even more, since, like most boys, he loves remote-control devices.
"How many boats will there be?"
"Well, that depends. Right now, I'm thinking we might need a ﬂeet of about three hundred to reverse the damage done to the climate since preindustrial times. We'll deploy them in different parts of the world, depending how much cooling is needed."
"How much will they cost to build?" Milo asked.
"About three million dollars each."
Milo nodded, as if that were entirely reasonable. "So how do they make clouds?"
"They don't make clouds," Salter replied carefully. "They brighten them."
Salter pointed to the Flettner rotors in the picture and said, "Inside each one of them is a sprayer, which will spray billions of tiny droplets of seawater into the sky. Some of those droplets -- we don't know exactly how many -- will be lifted up into the clouds, where the salt particles will act as cloud condensation nuclei. The water droplets that form on these particles will be smaller than the droplets that occur naturally in the clouds. And since clouds -- at least these low-lying clouds we're talking about over the ocean -- are really nothing more than water droplets in the sky, what happens if you make those droplets smaller?"
Milo thought for a moment. "They get brighter?"
"So this is how you're going to save the planet?" Milo asked skeptically.
"Well, this is one idea," Salter said, hesitating only slightly. "We still have a lot of work to do."
Jeff Goodell's "How to Cool the Planet: Geoengineering and the Audacious Quest to Fix Earth's Climate" will be published by Houghton Mifflin Harcourt on April 15.