Late in 1966, in the sprawling computer lab of the Washington, D.C., office building that housed the United States Weather Bureau, Syukuro Manabe was waiting for a print job to finish. At stake was the fate of the planet. Manabe, who was thirty-five, had come to the U.S. from Japan almost a decade earlier. He managed a team of computer programmers, tasked with building a mathematical simulation of the planet’s atmosphere. It had taken years to perfect, and cost millions of dollars. Now the simulation was complete.
With an alarming clatter, the printer came to life, and a single continuous sheet, striped in light-green and white, unspooled to the floor. The I.B.M. 1403 could print six hundred lines per minute, but Manabe couldn’t stand the noise it made, and usually avoided it by going out for lunch. This job couldn’t wait. If successful, Manabe’s simulation would quantify, for the first time, the relationship between carbon dioxide and the temperature of Earth’s atmosphere.
That the Earth’s atmosphere retained heat from sunlight had been understood since the early nineteenth century. Water vapor was the primary driver, trapping heat energy at lower altitudes and warming the planet’s surface by about sixty degrees Fahrenheit. (If Earth had no atmosphere, its surface temperature would average zero degrees Fahrenheit.) The open question was whether other atmospheric gases contributed to this greenhouse effect. Carbon dioxide was thought to have an effect, but it made up just three parts per ten thousand of Earth’s atmosphere by volume. Researchers wondered whether its impact was detectable.
Manabe speculated that it was. Three parts per ten thousand wasn’t much, but even a trace gas, with the right properties, could have an outsized impact. Without carbon dioxide, there would be no photosynthesis, and almost everything on the planet would die. Perhaps moving carbon-dioxide levels in the other direction—as the combustion of fossil fuels was doing—would have a similarly catastrophic effect.
There was no direct way to test this hypothesis; Manabe, who lived on Earth, did not have access to another, disposable planet on which to run experiments. Instead, he had to simulate the effects of atmospheric change from equations in basic thermodynamics. For the planet’s surface, these equations could be done by hand, but once additional atmospheric layers were added, the calculations grew more complex.
Fortunately, Manabe had access to a machine called Stretch, one of the most powerful computers ever built. Officially, it was an I.B.M. 7030, designed, at the request of the Pentagon, to simulate the effects of the hydrogen bomb. Nine such computers had been produced; others had been sent to the Los Alamos National Laboratory and the National Security Agency. This one, after much lobbying by Manabe’s boss, had been assigned to weather forecasting, to demonstrate to the public that computers could be useful. Stretch was larger than a single-family home, and had sixty freestanding components. The complete apparatus weighed about thirty-five tons, and was cooled by an air conditioner the size of a studio apartment.
Manabe had arrived in the U.S. in 1958; he had never before left Japan, and he spoke little English. But he shared his colleagues’ fascination with computer technology, and, outfitted with the default sportcoat and skinny tie, he fit in quickly. He was attracted to America’s informal social norms, which he preferred to Japan’s more hierarchical approach. “The hardest part was the Western toilet,” Manabe told me last year. “I’d never seen one before.”
Manabe eventually secured a post at Princeton, where he lives today. Last week, at the age of ninety, he was awarded the Nobel Prize in Physics. The prize committee cited Manabe’s 1966 simulation as the first reliable prediction of climate change. The simulation included a plot of points representing the sensitivity of Earth’s temperature to carbon dioxide at different altitudes. The printer didn’t have the capability to fit a curve to the data, so, for the final step, Manabe had to draw it in himself. “I used a pencil,” he said. “It took a long time.”
Manabe’s pencil-line graph revealed three unexpected results. First, according to the simulation, boosting carbon dioxide from three parts per ten thousand to six could cause Earth’s average surface temperature to rise by more than four degrees Fahrenheit. A comparable temperature increase at the end of the last Ice Age had caused ocean levels to rise a hundred feet.
Second, Manabe’s simulation predicted that carbon dioxide would trap heat energy in the lower atmosphere. The Earth’s surface and its oceans would therefore get hotter, while the upper atmosphere would cool. This combination—cooler above, hotter below—is now regarded by climatologists as the smoking gun of human-caused climate change. (Other potential causes of global warming, like the sun growing brighter, would uniformly heat the atmosphere at every altitude.)
Finally, Manabe’s model implied that, as the upper atmosphere cooled, it would deform, causing atmospheric boundaries to pancake. The 1966 pencil-line graph was the first preview of the Earth’s future: the surface was going to cook, and the sky was going to collapse.
Syukuro Manabe was born in September, 1931, on the island of Shikoku, south of the main island of Honshu. His family lived in an isolated mountain hamlet, where his father was the village doctor. On the day Manabe turned three, the Muroto typhoon, then the deadliest storm in Japan’s history, made landfall on Shikoku, destroying thirty thousand homes and leaving three thousand people dead. Powerful cyclones captivated Manabe as a child. “I had a horrible memory and I was clumsy with my hands,” he told a Japanese newspaper. “My only good trait was to gaze at the sky.”
When Manabe was ten, the Japanese Navy bombed Pearl Harbor. In 1944, when he was thirteen, U.S. forces launched one of the largest bombing campaigns in history against mainland Japan. Shikoku was not a target, but bombing convoys would fly over the island on their way to Honshu. While his fellow-students hid out in bomb shelters, Manabe studied for his exams. “Fortunately the airplanes just passed over us, because we’re in the countryside in middle school,” he told an oral historian. Across the channel from Shikoku sat Hiroshima; one of the planes that flew over the island was the Enola Gay.
Manabe has downplayed the impact of his wartime upbringing. “The war didn’t bother me at all,” he said. “I just kept on preparing for the entrance examination.” But he has acknowledged one long-term effect. “I didn’t grow as much as I should have,” he said. “I was undernourished all the time.” The postwar American occupation brought prosperity. In 1955, the Toyota Motor Corporation introduced its first mass-market car. As the middle class recovered, Japanese households sought to acquire the “Three Sacred Treasures”: a television, a refrigerator, and a washing machine. In the decades following the introduction of Western foodstuffs, the average height of an adult Japanese man increased by nearly four inches. Such advancements were spurred by immense growth in the use of fossil fuels.
Manabe aced his entrance examination to the University of Tokyo. His brother, father, and grandfather were all physicians, but Manabe decided to be a physicist. “Then I realized, I’m not that good in math, to get into the difficult physics,” he said. “I’m not that good at measuring things, either. And I had dropped out of biology, because I’m not good at memorizing things.” Manabe ended up in meteorology.
He was a patient student. Struggling to follow some of his professors’ lectures, he learned meteorological physics at his own pace, and had to retake at least one exam. But, when Manabe and his fellow graduate students used these physics equations to predict the weather, he emerged as one of the stars of the department. Lacking access to a computer, the students made calculations on graph paper by hand. “I would spend hours drawing contour lines,” Manabe told me. He seemed nostalgic for the practice: “Drawing contours yourself, you can begin to notice things you’ve never noticed before. Maybe this primitive process is good, in some sense.”