Which French mathematician first described the greenhouse effect in 1824?

The French mathematician who first described the greenhouse effect in 1824 was Joseph Fourier.

Fourier is best known for developing mathematical methods used to study heat and periodic processes, but he also made a foundational insight about Earth's climate. In a 1824 paper, he argued that Earth's atmosphere helps keep the planet warmer than it would be if it received sunlight but had no atmosphere.

Fourier did not identify the modern list of greenhouse gases or fully explain infrared absorption. His contribution was the physical idea that the atmosphere regulates Earth's temperature by affecting how heat escapes to space. Later scientists supplied the missing mechanisms: Eunice Newton Foote and John Tyndall investigated the heat-absorbing properties of gases, while Svante Arrhenius quantified carbon dioxide's possible warming effect.

Nils Gustaf Ekholm wrote later about atmospheric carbon dioxide and climate, but he was not the first to describe the greenhouse effect. The term itself also came later, so Fourier's 1824 work is usually treated as the starting point of the scientific history of the greenhouse effect.