Arrhenius calculates the greenhouse effect

In 1896 the Swedish chemist Svante Arrhenius presented to the Stockholm Physics Society, and then published in the Philosophical Magazine, a paper on how carbon dioxide in the air affects the temperature of the ground. By long hand calculation, using Samuel Langley's measurements of infrared moonlight, he estimated that halving the carbon dioxide would cool the Earth by about 4 to 5 degrees C, enough for an ice age, and that doubling it would warm the planet by about 5 to 6 degrees C. Modern estimates for a doubling, from the IPCC, fall at about 2.5 to 4 degrees C.¹²

He built on Tyndall's laboratory finding that carbon dioxide traps heat, and on Fourier's earlier argument that the atmosphere keeps the Earth warm. His original aim was to explain the ice ages, prompted by his colleague Arvid Hogbom's estimate that factories already emitted carbon dioxide comparable to natural sources. Arrhenius calculated that burning coal might double the gas in about 3,000 years and welcomed the prospect, expecting milder climates and larger harvests. He did not foresee the pace of growth in fossil fuel use.¹

The idea fell out of favor for decades. In 1900 Knut Angstrom argued that carbon dioxide already absorbed all the available infrared and the oceans would take up any excess. Guy Callendar revived the case in 1938, and Roger Revelle and Hans Suess showed in 1957 that the oceans do not absorb the gas as fast as feared. Charles Keeling's measurements from 1958 then showed the carbon dioxide level rising year after year.¹