laboratory—coal gas—otherwise known as town gas. This was a carbon-bearing gas, primarily methane made by heating coal, that was pumped into his laboratory by the local London lighting company to burn in order to provide illumination—pre-electricity. When Tyndall put the coal gas into the spectrophotometer, he found that the gas, though invisible to the eye, was opaque to light; it darkened. Here was his proof. It was trapping infrared light. He then tried water and carbon dioxide. They too were opaque. That meant that they too trapped heat.
By this point, Tyndall was close to collapse from continual ten-hour days in the laboratory and from his inhalation of fumes—of “gases not natural even to the atmosphere of London.” But that did not matter. He was elated. “Experimented all day,” he wrote in his journal on May 18, 1859, adding joyously, “The subject is completely in my hands!” Just three weeks later, he delivered a public lecture at the Royal Institution—with Prince Albert, the Prince Consort of Queen Victoria, in the chair—demonstrating and explaining his discovery and its significance. There on Albemarle Street, just off Piccadilly, was “the first public, experimentally based account” of the greenhouse effect.7
“As a dam built across a river causes a local deepening of the stream, so our atmosphere, thrown as a barrier across the terrestrial (infrared) rays, produces a local heightening of the temperature at the Earth’s surface,” said Tyndall. “Without the atmosphere, you would assuredly destroy every plant capable of being destroyed by a freezing temperature.... The atmosphere admits of the entrance of the solar heat, but checks its exit; the result is a tendency to accumulate heat at the surface of the planet.”
What Tyndall had done in his basement laboratory was to provide the explanation for the greenhouse effect, for how climate worked, and for how, in his words, “every variation” of the constituents of the atmosphere “must produce a change of climate.” He gave particular credit to Saussure and Fourier. Here also was a confirmation for Louis Agassiz’s theory of the Ice Age. For variations in the balance of gases in the atmosphere “may have produced all the mutations of climate which the researches of geologists reveal.”
Tyndall went on to make other important contributions to science and gained great renown. Until late in life, he would also regularly return to Switzerland to take in the glaciers and climb the peaks. After a life as a mountaineer, undertaking many dangerous and daring mountain expeditions, including a number of near fatal accidents, Tyndall died in 1893, at age 73, under more prosaic circumstances. His wife had accidentally administered an overdose of sleep nostrum to relieve his intolerable insomnia. As he slipped away, he murmured, “My poor darling, you have killed your John.”8
ARRHENIUS: THE GREAT BENEFIT OF A WARMING CLIMATE
The year after Tyndall’s death, in 1894, a Swedish chemist named Svante Arrhenius picked up the story. Arrhenius was curious as to what effects increasing or decreasing levels of carbon dioxide—or carbonic acid, as it was called at the time—would have on the climate. He too wanted to weigh in on the mechanisms of the ice ages, the advance and retreat of glaciers, and what he called “some points in geological climatology.”
Arrhenius’s own academic career was not smooth. He had difficulty getting his Ph.D. accepted at the University of Uppsala. But now, more established in Stockholm, he found his interest in carbon and the ice age stoked in a scientific seminar that met on Saturdays. Melancholic over his divorce and loss of custody of his son, and with much time on his hands, Arrehenius threw himself into month after month of tedious calculations, sometimes working 14 hours a day, proceeding latitude by latitude, trying by hand to calculate the effects of changes in carbon.
After a year, Arrhenius had the results. Invoking Tyndall and Fourier, he said, “A great deal has been written on the influence of the absorption of the atmosphere upon the climate.” His calculations showed that cutting atmospheric carbon in half would lower the world’s temperature by about four to five degrees centigrade. Additional work indicated that a doubling of carbon dioxide would increase temperatures by five to six degrees centigrade. Arrhenius did not have the benefit of supercomputers and advanced computation; he arrived at the above prediction after a tediously huge number of calculations by hand. Nonetheless, his results are in the range of contemporary models.9
Even if he was the first to predict, at least to some degree, global warming, Arrhenius was certainly not worried