The story of the greenhouse effect begins nearly two centuries ago, in the early 19^{th} century, with the work of the French Jean-Baptiste Joseph Fourier (21 March 1768 – 16 May 1830). Fourier, an ambiguous personality, was a mathematician, a scientist, and a member and secretary of the French Academy of Sciences. He was a friend of Napoleon, governor of Egypt and a promoter of the French Revolution. He was imprisoned, twice. His reputation is largely based on his ‘Fourier Series’ a widely used mathematical technique in which complex functions can be represented by a series of sines and cosines.

Fourier’s article of 1824 “*Mémoire* sur la *température* du *globe terrestre et des espaces* planétaires” (On the Temperatures of the Terrestrial Sphere and Interplanetary Space) has been often mentioned as the first reference in the literature to the atmospheric ‘greenhouse effect’. In this article, Fourier presented some ‘general remarks’ on the temperature of the Earth, but he never mentioned a greenhouse and actually he told his readers that the ‘analytic details which are omitted here are published in the works which I have already published’.[1] Fourier’s main contribution of his 1824 article is the introduction of planetary temperature. He distinguishes three sources from which the Earth derives its heat:

“*The Earth receives the rays of the Sun, which penetrate its mass and are converted there into dark heat; the Earth also possesses heat of its own which it retains from its origin, and which dissipates continually at the surface; finally, this planet receives rays of light and heat from the countless stars among which the solar system is located. These are the three general causes which determine terrestrial temperatures.”*[2]

Fourier established the concept of an energy balance for Earth and planets and discovered that planets reflect part of the solar light (today, it is called albedo) as well as losing energy by infrared radiation, which had been discovered by Frederick William Herschel 25 years earlier. Fourier called this energy “chaleur obscure” or ‘dark heat’. He examined each of the three sources from which Earth derives its hear and the phenomena they produce, including the heating of the atmosphere, but he did not set out to think about climate change.

Fourier compared the heating of the atmosphere to the action of a heliothermometer, an instrument which was designed and was used in scientific mountaineering in the 1760s by Horace Benedict de Saussure. James R. Fleming describes the instrument in his book Historical Perspectives on Climate Change[3],

“*It consisted of a small wooden box lined with a layer of black cork. Sunlight entered the box of glass separated by air spaces. This arrangement served to magnify the heating effect of the Sun’s rays (measured by a thermometer enclosed in the box) while eliminating the cooling effect of wind currents*.”

For Fourier, the atmosphere was like a giant heliothermometer, ‘sandwiched between the surface of the Earth and an imaginary cap provided by the finite temperature of interstellar space’. He didn’t used the term greenhouse, but a different metaphor: “diaphanous envelope.” Nevertheless, he got the essence of the greenhouse effect right.

Fourier’s article of 1824, was mentioned by John Tyndall, Svante Arrhenious, and by many others. Today, many scientific review articles also cite Fourier’s article, but most of them contain brief historical references typically drawn from secondary rather the original sources. “Those seeking to understand Fourier’s scientific contributions to climate change need to look well beyond the secondary literature”, says James Fleming. It is in his magnus opus, *Théorie analytique de la chaleur* (Analytic Theory of Heat) [4] where Fourier discusses the problem of terrestrial temperatures and the principles governing the temperature of a green-house (*serre* in French). He argues that the mean temperature of the earth would be on the rise, if the heat acquired from the radiation of the sun were not balanced by that which escapes in rays from all points of the earth’s surface.[5]

References:

[1] Herivel J, (1975), *Joseph Fourier: The Man and the Physicist*, Claredon Press

[2] Jean-Baptiste Joseph Fourier. On the Temperatures of the Terrestrial Sphere and Interplanetary Space, translated by R. T. Pierrehumbert https://geosci.uchicago.edu/~rtp1/papers/Fourier1827Trans.pdf

[3] Fleming, James Rodger ‘ *Historical Perspectives on Climate Change*, Oxford University Press (19 May 2005)

[4] Joseph, Fourier, The analytical theory of heat, (translated with notes by Alexander Freeman, University Press, Cambridge, 1878) 3-4

[5] In his essay published in 1824, Fourier presented the “Theorie Mathematique de la Chaleur” (Theory of Heat), where he argued that the mean temperature of the earth would be on the rise, if the heat acquired from the radiation of the sun were not balanced by that which escapes in rays from all points of the earth’s surface

Image: Fourier’s grave, Père Lachaise Cemetery (Coyau / Wikimedia Commons, via Wikimedia Commons)

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