Climate change from the ground up

Svante Arrhenius was an optimist by nature. He believed that science should – and could – be accessible to all. In 1891 he got his first teaching job at an experimental university in Stockholm called Högskola. In the same year, he founded the Stockholm Physics Society, which met every Saturday evening. For a fee of one Swedish crown, anyone could join. Among the Society’s first members was a Hojschule student named Sophia Rudbeck, who was described by a contemporary as an “excellent chemist” and “a charming beauty”. Arrhenius began writing her poetry, and the two soon married.

The meetings of the Physical Society consisted of lectures on the latest scientific developments, many of them delivered by Arrhenius himself, followed by discussions that often lasted into the night. The subjects varied widely, from aeronautics to volcanology. The Society devoted several sessions to considering the tools that would be needed by Salomon Auguste Andre, another early member of the group, who had decided to attempt to reach the North Pole by balloon. (Whatever his tools, Andre’s journey will lead to his death and the deaths of his two companions.)

A question that particularly interested the Physics Society was the origin of the ice ages. And all over Sweden marked the glaciers that buried the country for long periods of time: boulders with parallel scrapes; strange sinuous gravel heaps; Huge boulders that have been transported far from their source. But what caused the great ice sheets to descend, carrying away everything in front of them? Then what caused them to retreat, allowing the rivers to flow again and the forests to return? In 1893, the Society discussed several theories that had been proposed, including one linking ice ages to slight variations in the Earth’s orbit. The following year, Arrhenius came up with a different—and he thought better—idea: carbon dioxide.

He knew that carbon dioxide had strange heat-trapping properties. In the atmosphere, it allowed visible light to pass through, but absorbed the longer wavelength radiation that Earth constantly emits into space. What if Arrhenius speculated on the amount of carbon dioxide2 in the air differed? Could this explain the ebb and flow of glaciers?

The mathematics used to test this theory far exceeded what was possible at the time. Arrhenius did not have a calculator, let alone a computer. It lacked crucial information about which wavelengths, exactly, the carbon dioxide is2 sucks. Meanwhile, the climate system is very complex, with feedback loops within feedback loops.

Arrhenius, who later won a Nobel Prize for an unrelated discovery, moved on anyway. On Christmas Eve of 1894, he began building a climate model – the first in the world. He compiled temperature data from around the world and ingeniously used a set of measurements made a decade earlier by American astronomer Samuel Pierpont Langley. (Langley had invented a device—a bolometer—to measure infrared radiation, and used it to determine the moon’s temperature.) Arrhenius made thousands of calculations—perhaps tens of thousands—and often worked fourteen hours a day on the task. He was still counting away as his marriage fell apart. In September 1895, Rudbeck was gone. In November, without ever seeing Arrhenius again, she gave birth to their son. The following month, Arrhenius finished his work. “I certainly should not have made these tedious calculations,” he wrote, “if there had not been some extraordinary interest attached to them.”

Arrhenius believed he had solved the mystery of the ice ages, a mystery that “hitherto has been difficult to explain”. He was at least partially right: ice ages are the product of a complex interplay of forces, including wobbles in Earth’s orbit. And the Changes in carbon dioxide in the atmosphere2.

Turns out his model has another use, too. Across Europe and North America, coal was shoveled in carbon dioxide penetrating furnaces. By thickening the atmosphere that has warmed the Earth, humans should, Arrhenius argued, alter the climate. He calculated that if the amount of carbon dioxide in the air doubled, global temperatures would rise between three and four degrees Celsius. After a few quadrillion calculations, vastly more advanced climate models predict a doubling of carbon dioxide2 Temperatures would be pushed to between 2.5 and 4 degrees Celsius, which meant that Arrhenius’ pen-and-paper estimate was, to an unusual degree, on target.

Arrhenius thought the future he conjured would be interesting. He predicted that “our descendants will lead happier lives ‘under warmer skies'”. The possibility, however, was remote; a doubling of atmospheric carbon dioxide2 It was believed that humanity would take three thousand years.

It is easy now to make fun of Arrhenius for his radiance. The doubling threshold could be reached in a matter of decades, and the results could be catastrophic. But which of us is different? Here we are all watching things fall apart. However, deep down, we don’t believe it.

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