Which Swedish scientist calculated that doubling CO2 could raise Earth’s temperature?

The Swedish scientist who calculated that doubling atmospheric carbon dioxide could raise Earth’s temperature was Svante Arrhenius.

In 1896, Arrhenius used physical chemistry and infrared observations to estimate how changing atmospheric carbon dioxide would affect surface temperature. He was investigating whether greenhouse gases could help explain the alternation of ice ages and warmer periods. His original estimate for a doubling of CO₂ was roughly 5–6°C of warming; he later revised the figure to about 4°C.

Arrhenius recognized that water vapor could amplify warming because warmer air can hold more moisture. His work built on earlier ideas from Joseph Fourier and John Tyndall, who had described the atmosphere’s heat-trapping behavior and measured infrared absorption by gases.

His calculation was not a modern climate model: it omitted clouds, convection, and several atmospheric processes. Still, it was the first quantitative prediction of global warming from increased carbon dioxide. Guy Callendar later assembled evidence of rising CO₂ and warming, while Charles Keeling established precise long-term measurements.