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The Man Who Predicted Climate Change

The Man Who Predicted Climate Change

Syukuro Manabe smiles in an office full of papers and maps.

Syukuro Manabe, late in 1966, waited for a job to be completed in the sprawling computer laboratory of the Washington, D.C. office building that housed United States Weather Bureau. The fate of the entire planet was at stake. Manabe, now 35, had arrived in the U.S. almost a decade ago from Japan. He managed a team of computer programmers, tasked with building a mathematical simulation of the planet’s atmosphere. It took years to perfect and cost millions of money. The simulation was now complete.

Syukuro Manabe’s models were among the first to reliably assess the effects of increased CO2 in the atmosphere.Photograph courtesy Geophysical Fluid Dynamics Laboratory

The printer was activated with a loud clatter. One continuous sheet of light-green and dark-green striped paper was then 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. (Earth’s surface temperature would be zero degrees Fahrenheit if it had no atmosphere. It was not clear if other atmospheric gases contributed to the 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 were unsure if it was detectable.

Manabe speculated that it might be. 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 wouldn’t be photosynthesis and nearly everything on the planet will die. Perhaps moving carbon-dioxide levels in the other direction—as the combustion of fossil fuels was doing—would have a similarly catastrophic effect.

Manabe lived on Earth and did not have the opportunity to test his hypothesis. Instead, he had the task of simulating the effects of atmospheric changes using basic thermodynamics equations. For the planet’s surface, these equations could be done by hand, but once additional atmospheric layers were added, the calculations grew more complex.

Manabe was fortunate to have access to Stretch, one the most powerful computers ever made. It was officially an I.B.M. It was an I.B.M. 7030, which was created at the Pentagon’s request to simulate the effects the hydrogen bomb. Nine of these computers had been made; the National Security Agency and Los Alamos National Laboratory had received others. 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 that a single-family house and had sixty independent components. The entire apparatus weighed around thirty-five tons and was cooled using an air conditioner as small as a studio apartment.

Manabe arrived in the U.S. from Japan in 1958. He had never been to Japan before and knew very 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 obtained a position at Princeton, where he still lives. Last week, he was awarded Nobel Prize in Physics at the age of ninety. 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 was recently awarded Nobel Prize in Physics.Photograph from Kyodo / AP

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. Similar temperature increases had led to ocean levels rising 100 feet after the end of the last Ice Age.

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 for global warming, such as the sun getting brighter, would also heat the atmosphere uniformly at all altitudes.

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.

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Syukuro Manabe was conceived on September 19, 1931, on the Shikoku island, south of Honshu. His family lived in a mountain hamlet where his father was a 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. Manabe was captivated by powerful cyclones 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.”

Manabe was just ten when the Japanese Navy attacked Pearl Harbor. When he was thirteen years old, the U.S. launched one their largest ever bombing campaigns against Japan. Although Shikoku was not an intended target, bombing convoys flew over the island as they traveled to Honshu. Manabe, on the other hand, studied for his exams while his fellow students hid in bomb shelters. “Fortunately the airplanes just passed over us, because we’re in the countryside in middle school,” he told an oral historian. Hiroshima was sitting across the channel from Shikoku; the Enola Gay was one of the planes to fly over the island.

Manabe has downplayed any effects 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, 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. The average Japanese man grew nearly four inches in the decades that followed the introduction of Western foodstuffs. These advances were made possible by the enormous growth in fossil fuel usage.

Manabe passed the University of Tokyo entrance exam. Manabe chose to become a physicist because his grandfather, brother, and father were all doctors. “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. Manabe, along with his fellow graduate students, used these equations to predict weather. He was one of the department’s most prominent figures. The students had no access to computers so they did calculations on graph paper. “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.”

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