The Wave

by Susan Casey

  On a postcard-perfect evening in mid-November I drove down the two-lane road that runs along those twisty seven miles, from Haleiwa with its sign declaring it the “World Surf Capital,” and then on past Himalayas, Alligators, Waimea Bay, Log Cabins, Back Door, Pipeline, Sunset Beach, Backyards, Velzyland, and Phantoms—a chorus line of famous waves. Along the way I dodged cyclists and skateboarders and jaywalkers running barefoot across the road to the beach, all of them carrying surfboards. Big-wave season was in high gear, but I hadn’t come to watch people ride those waves. I was here to listen to people talk about them. At the northern tip of the island I turned into the Turtle Bay Resort.

  In the lobby sunburned families booked snorkeling excursions, and honeymooning couples drank mai tais and nuzzled. Trade winds blew in from the ocean. Hawaiian Muzak enveloped the place like a cloud. And over in Ballroom One, 120 scientists attending the Tenth International Workshop on Wave Hindcasting and Forecasting and Coastal Hazard Symposium milled around at their icebreaker cocktail party, temporarily tripling the north shore’s per capita IQ.

  Every two years the world’s most eminent wave scientists gather somewhere to exchange information, present papers, compare notes, and above all, to argue. It was a big-wave group every bit as elite as the one that had descended on Tahiti, except that here the wave action involved risks of another sort; how human interests might coexist with things like fifty-foot storm surges, ship-busting rogue waves, and extra-strength hurricanes.

  Contrary to stereotype, these scientists were a diverse, healthy-looking crew. There was the usual raft of thick glasses and tufts of facial hair, but there were also a heartening number of women in the group, as well as a younger contingent in baggy shorts and flip-flops that wouldn’t have looked out of place down the road at Pipeline. After the 2004 Indonesian tsunami and the inundation of New Orleans, and amid growing concerns about how drastically climate change was likely to affect the oceans, wave science had become a hot topic, and fresh energy was pouring in. The field had come a long way since World War II, when military planners, realizing that stealthy beach landings required accurate surf forecasts, were dismayed to discover that nothing of the sort existed. (For scientists, nothing guarantees job security more than working on something considered useful for war.)

  The conference chairs, Don Resio and Val Swail, stood by the registration table and greeted attendees. I walked over to introduce myself; I’d spoken on the phone to Resio, a senior research scientist from the U.S. Army Corps of Engineers, and he had agreed to let me come to the conference. Even as a disembodied voice he was instantly likable, but in person Resio had the kind of natural magnetism politicians dream of. He was a tallish, jovial Virginian with a silver brush cut and a neat goatee. When he smiled, which was often, he revealed a set of perfect white teeth. “Ah, hello!” he said, shaking my hand. “Welcome, welcome. It’s wonderful to have you here.” Despite my gate-crashing status, Resio meant it. He had only one concern: that I wouldn’t understand a word of the conference.

  It was a valid worry. At this level the study of waves involved quantum mechanics, chaos theory, advanced calculus, vortex turbulence equations, and atomic physics. I was a little rusty on those things. “Don’t worry,” Resio’s co-chair Val Swail said, with a wry smile. “When they start in with the equations it’s over our heads too.” Swail, an outdoorsy-looking Canadian with a shock of gray hair and a ruddy complexion, worked on the leading edge of climate research for that country’s government. He looked at me sympathetically. “And no one understands Vladimir [Zakharov]. He uses five integrals. The rest of us use two.”

  As if to illustrate their point, blowups of scientific papers lined the ballroom. They had titles like “Spectral Wave Modeling of Swell Transformations in Indigenous Marshallese Navigation” and “Blended Global High Resolution Sea Surface Forcing Parameters for Numerical Ocean Modeling.” I looked at a printout of one of them, thick with math. The posters ranged from graphic extravaganzas—the kind of thing you get as a bonus when you subscribe to National Geographic—to one halfhearted effort consisting of a black-and-white piece of letter-size paper stapled to the wall. There were charts that looked as if they’d been sprayed with buckshot, and graphs that resembled solar systems. As I browsed the presentations I overheard snatches of conversation. “I was puzzled a little bit myself about the high-frequency tail breaking,” a Japanese scientist said. “Naturally,” an Italian scientist replied. “You contend there is a power law for wind-wave interaction,” a stern-faced man said in a strong German accent. “I think that is a questionable assumption.”

  On the far side of the ballroom I came across a paper I could actually understand, a colorful affair illustrated with photographs of giant waves crashing down, titled “Prototyping Fine Resolution Operational Wave Forecasts for the Northwest Atlantic.” The bottom line on this one, it seemed, was that we are bad at forecasting wave behavior in the most extreme storms. “Are storms becoming stronger?” I asked its author, Canadian scientist Bash Toulany, standing nearby. “That’s a tricky question,” he said. “It has to do with sea surface temperatures and—”

  A cheerful voice over my shoulder cut in. “Oh, we’re gonna get smacked. No doubt.” I turned to the speaker, a happy-looking dark-haired man in glasses, in his early forties. His name was Dave Levinson, and he was a climatologist from the National Oceanic and Atmospheric Administration (NOAA).

  “Smacked?” I said. “By climate change?”

  Levinson nodded. “We have some major challenges coming up that are pretty heavy-duty. Do you need another beer?”

  For all his humor and ability to communicate with a layman, Levinson was a dead-serious expert, and the conference chair on climate change. He had an excitable air. When he spoke, the words poured out of him at high speed, as if everything was so insanely fascinating there might not be enough time to get it all across. “I’m into storms,” he told me. “I’ve always been into storms.” From growing up in Chicago, Levinson had fond childhood memories of smiting midwestern blizzards that blanketed the region: “All the cars would be off the road and we’d go cross-country skiing.”

  Although global warming means less snow, there are many indications that we won’t lack for terrible storms. According to Levinson, we were in for major changes—if not outright fire-and-brimstone disaster—when it came to ocean behavior. “You’ve got a couple things going on,” he said. “You’ve got storm tracks shifting. You’ve got water levels rising.” This was undeniable. The global average sea level rose approximately 6.7 inches in the twentieth century, and the rate is accelerating: a conservative estimate for the next hundred years would add another twelve inches to current levels; some scientists believe it will be more like six feet.

  Melting ice contributes to higher sea levels, of course, as do warmer ocean temperatures, because water expands as it heats. While scientists are divided over whether a warmer ocean will result in more frequent storms, they do know that the strongest storms are intensifying. (Warmer ocean temperatures also mean more wind, and hurricane strength rises exponentially with wind speed.)

  At the same time, in certain areas, the North Pacific and the Southern Ocean for instance, wave energy is increasing. These brawnier waves have the potential to cause damage wherever they hit, but they are extra-destructive at the coastlines, where they cause severe erosion, property damage, and death. During any given year the news reports numerous stories of waves sweeping shoreline observers off piers and promontories and beaches.

  In places where sea ice or coral reefs have acted as natural wave barricades, that protection disappears if the ice melts or the reefs crumble (from exposure to stronger waves). Storm surges can then make deeper inroads, and the whole feedback loop continues. When you take in the interconnectedness of the entire system—and the fact that nine of the world’s ten largest cities are located on low-lying coastal land—the warming oceans are one huge, nasty set of tumbling dominoes. “You hate to be dire,” Levinson said, “
but …” His voice trailed off.

  A wave might seem to be a simple thing, but in fact it’s the most complicated form in nature. Scientists even find it difficult to agree on a basic, all-around definition of what a wave is. Many, but not all, waves move a disturbance through a medium. That disturbance is usually, but not always, energy. A wave can store that energy or dissipate it. Paradoxically, it’s both an object and a motion. When wave energy does move through a medium—water, for instance—the medium itself doesn’t actually go anywhere. In other words, when a wave rises in the ocean and appears to race across the surface, that specific patch of water is not really advancing—the wave energy is. It’s like cracking a whip. As energy passes through the ocean, it spins the water molecules in a roughly circular orbit, temporarily lifting them. Only when the wave is about to break, on a beach, say, do the water molecules shift locale—and even then just slightly—as they pitch forward onto the sand.

  In order to exist, waves require a disturbing force and a restoring force. In the ocean that disturbing force is usually, but not always, the wind. (Earthquakes, underwater landslides, and the gravitational pull of the sun and the moon can also play this role.) The restoring force is usually, but not always, gravity. (In minuscule waves it can be the capillary action of the water itself.) All of this goes to explain why, if you’re serious about trying to pin down a wave, you turn to equations rather than words. Because waves do all sorts of bizarre stuff.

  There’s the standing wave, in which energy moves in two opposing directions, and the Love wave, which travels only through solids. Gamma-ray waves—tiny, superenergetic electromagnetic waves—can kill living cells. Many scientists have named waves after themselves, resulting in such mouthfuls as the Tollmien-Schlichting wave. The X-wave (short for “extraordinary”) is a slippery beast; it appears to zip around faster than light, theoretically allowing it to move backward in time. Then there are the mysterious gravitational waves that, according to the theory of general relativity, flex the surface of space-time. But we have to take Einstein’s word for that, because nobody’s ever encountered one.

  Despite their differences, waves do share some traits. They’re defined according to wavelength, the distance between two consecutive crests; and period, which represents the same measurement in time. Taken together, wavelength and period determine speed: longer means faster. (Tsunamis, waves caused by sudden lurchings of the earth’s crust, are the ocean’s speed champions. Their wavelengths can be more than one hundred miles long, and they can travel faster than jets.) Longer-period ocean waves, anything over twelve seconds, are the ones sought after by big-wave surfers because they contain the most energy and thus create the largest faces when they break. Their power comes from the wind transferring its energy into the water over a stretch of miles (a distance technically known as a “fetch”), so the most formidable waves emerge in places like the North Atlantic, the North Pacific, and the Southern Ocean, where storm winds yowl across vast areas of sea, long fetches uninterrupted by land.

  Another thing waves have in common is that despite science’s efforts to dissect them, they defy total explanation. Reading through a basic oceanography text, I came across this sentence: “How wind causes water to form waves is easy to understand although many intricate details still lack a satisfactory theory.” One French scientist put it to me bluntly: “People have been studying waves for so many years, and we’re still struggling to understand how they work.”

  The conference room was large, sunny, and triangular, with walls of windows looking out at the ocean. It was an idyllic place to discuss waves, like sitting in the prow of a glass-hulled boat. After a continental breakfast buffet and a traditional Hawaiian blessing to kick things off, people settled at long tables with their laptops. The session, Coastal Waves I, was led by a scientist named Al Osborne. He was a tall, solidly built man with wavy gray hair, wearing a blue hooded sweatshirt, and he stood at the podium with the casual manner of someone with nothing to prove. I was curious about Osborne, a Texas-born physicist who had attracted much media attention for managing to create freak waves in a simulation tank. Now based in Italy at the University of Turin, he had spent his career studying nonlinear dynamics in water, addressing the question of why some waves rolled along in a fairly normal fashion and others suddenly morphed into monsters. Generating them in a controlled environment was a major step toward figuring this out.

  Along with his colleague Miguel Onorato, a thirty-seven-year-old prodigy who was also attending the conference, Osborne had discovered that while freak waves did not play by traditional physics rules (straightforward linear theories proving that, in essence, one plus one equals two), they could be partially explained using quantum mechanics, the more exotic equations that describe atomic and subatomic behavior (nonlinear theories as to why, in chaotic environments, one plus one occasionally adds up to seventeen). Things become weird when examined through the quantum looking glass. Matter and energy can exist as both waves and particles, depending on conditions. Reality is revealed as a flexible construct, studded with parallel universes. It seemed like fascinating and twisted territory, and I made a mental note to seek out Osborne later.

  Onorato got up to present the first paper, “Three and Four Wave Exact Resonance Interactions in the Flat Bottom Boussinesq Equations.” This was not a kind and gentle start to the conference. From the title onward I found it flat-out incomprehensible, and judging by the looks on people’s faces around the room, I wasn’t alone. Onorato was a slim and striking Italian with the disheveled appearance that, for a scientist, serves as visual shorthand for eccentric brilliance. I may not get around to washing my pants, the look says, because I am too busy splitting this atom. As he clicked onto a slide of equations so dense it looked as though chickens had stepped in ink and scrambled across the screen, a Chinese man to my left let out a sharp exhalation.

  The bottom line, I was beginning to understand, is that wave science is mind-meltingly complex because waves themselves are that way. Elegant equations that describe how waves move through water were established back in the nineteenth century and are still useful today. But they were based on the notion that waves behaved in simple and predictable ways. While that may be the case if you drop a stone into a quiet pond, in the ocean the opposite is true: it is a field of constant, seething interactions between waves and wind and gravity; if each wave represents a note, then the ocean is playing the most intricate symphony imaginable. Teasing apart this chaos and corralling it into a neat package of numbers is a daunting prospect, but of all the exceptional minds that might be able to move the ball forward, many were in this room.

  Onorato wrapped up and asked for questions. Someone coughed nervously. There was a moment of awkward silence and then a deep, heavily accented voice boomed out from the front. The questioner, Russian scientist Vladimir Zakharov, went on for quite some time. They didn’t come any smarter than Zakharov, a barrel-chested man with snowy hair whose appearance brought to mind a smaller, friendlier Boris Yeltsin. I’d heard Zakharov, sixty-eight, author of the Zakharov Equation, described as “the father of nonlinear wave mechanics.” Of the fifty-three topics he had listed as his “research interests,” tossed in somewhere near the middle was “Construction of new exact solutions to the Einstein equations.” He and Onorato volleyed back and forth, speaking what seemed like their own private language, and then a third man joined in. This was Peter Janssen, a Dutch scientist from the European Centre for Medium-Range Weather Forecasts (ECMWF) in Reading, England. He was another titan, at the vanguard of wave research. Some of the world’s fastest computers resided at the ECMWF, humming away on Janssen’s latest initiative: a marine forecast that attempted to predict the appearance of rogue waves.

  The presentations continued in a blur of wave theory while outside the real waves grew. Surfers streaked past, filling the windows. At the podium, a scientist discussed Wave Watch III, a mathematical model that simulated conditions in the global seas. Models are the linchpi
n of wave (and climate) science. Essentially, they’re colossal computer programs that interpret millions of readings from satellites, ocean buoys, wind arrays, weather balloons, and other sources. All of these data are being fed into the models constantly. The result, hopefully, is an ongoing picture of sea states, wind conditions, pressure zones, ocean circulation—and the interactions among the four—that can be used to forecast future climate behavior. Serious elbow grease goes into creating a model. Scientists are always rejiggering them and fine-tuning them for greater accuracy. Models like Wave Watch III are critical tools, massive scientific initiatives. Anyone who is trying to do anything anywhere near the ocean relies on them. There is only one problem with models: they are often wrong.

  Models, don’t forget, said that rogue waves were impossible. They demonstrated why the Draupner oil rig’s engineers didn’t need to worry about an eighty-five-foot wave showing up. They assured naval architects that the München was unsinkable in any storm. Models underpredict and overpredict and strike out completely at regular intervals. “We’ve got very sophisticated wave models,” one scientist told me. “They’re trying to reproduce what’s going on, and they’ve been stretched to the best performance you can get with the physics that’s in them. And yet they’re not reproducing the waves properly under certain conditions.”