A cylinder that stayed warm
In 1856, Eunice Newton Foote used an air pump, glass cylinders and thermometers to test how different gases responded to sunlight, and found that a cylinder filled with carbon dioxide heated up more than one filled with ordinary air and stayed warmer for longer once the sunlight was removed. From this she drew a conclusion that reached well beyond her own apparatus: an atmosphere containing more carbon dioxide would leave Earth’s surface warmer than one containing less, a claim that anticipated, in general terms, the mechanism now central to understanding modern climate change. Her paper, “Circumstances Affecting the Heat of the Sun’s Rays,” was presented at the American Association for the Advancement of Science’s August 1856 meeting and published that September in the American Journal of Science and Arts, apparently the first physics paper by an American woman to appear in a scientific journal.
Read by proxy at a scientific meeting
Foote’s experiment was comparative rather than merely descriptive: she tested moist air against dry air and against carbon dioxide specifically, isolating the variable she cared about by comparing cylinders under otherwise similar conditions of sunlight exposure. Because Foote was not a member of the American Association for the Advancement of Science, her paper had to be read on her behalf by Joseph Henry of the Smithsonian Institution, who introduced it by remarking that science belonged to no country and no sex, an aside that both credited her and pointed to the unusual position a woman doing physics occupied in 1856. John Tyndall, working independently three years later in 1859, carried out more precise laboratory measurements of infrared absorption by various gases and is generally credited as the person who established water vapour and carbon dioxide as the primary gases responsible for the effect, using instruments capable of a level of detail Foote’s simpler apparatus could not match.
A mechanism confirmed by everything since
Foote’s basic finding, that carbon dioxide absorbs and retains heat more than ordinary air, has held up completely and now sits at the centre of climate science: the physical mechanism she demonstrated crudely in 1856 is the same one that explains why rising atmospheric carbon dioxide, from roughly 313 parts per million in 1960 to over 400 parts per million by 2013, has driven measurable global warming. Later work refined the physics considerably, from Tyndall’s more precise gas-by-gas measurements in 1859 to Svante Arrhenius’s 1896 calculation predicting that doubling atmospheric carbon dioxide would raise global temperatures by roughly five to six degrees Celsius, a figure not far from modern estimates. Foote’s own priority, that she demonstrated the CO2-heat connection three years before Tyndall and stated its climate implication five years before anyone else, was confirmed by researchers examining the historical record closely rather than simply asserted after the fact.
Directionally right, not fully precise
What Foote’s own paper did not include was the detailed, gas-specific infrared measurement that later established exactly how the greenhouse mechanism works at a molecular level, since her apparatus could compare which gases retained more heat but could not isolate the specific radiative process, the absorption of longwave infrared radiation by asymmetric molecules like carbon dioxide and water vapour, responsible for the effect. That more precise physical account came from Tyndall in 1859 and was refined further by Arrhenius and others afterward. Foote’s paper also disappeared from the historical record for close to a century and a half, credited to no clear malice recorded in the sources but generally attributed to the broader bias against women and amateur scientists publishing outside formal academic institutions in the nineteenth century, a gap in the record rather than a documented act of active suppression.
Forgotten for a century and a half
Foote’s rediscovery matters for climate science’s public history as much as for its physics, since it shifts the usual origin story back by several years and relocates it, at least in part, to an American woman working with simple, self-built apparatus rather than to European laboratory physicists working with more sophisticated instruments. Her work is now cited directly in discussions of how the basic mechanism behind anthropogenic climate change, more heat-trapping gas in the atmosphere means a warmer surface, was understood in outline well over a century before it became an urgent policy question, undercutting any claim that the underlying physics is a recent or contested addition to climate science. The American Geophysical Union’s 2022 establishment of the Eunice Newton Foote Medal formalised this recognition, attaching her name permanently to the field she had a documented, if long-overlooked, hand in founding.
A priority claim restored by research, not assumption
This is worth the time both for the physics, a genuinely early and directionally correct demonstration of the mechanism behind modern climate change, and for the history of how credit in science gets assigned and later corrected. It rewards attention to the specific timeline, three years ahead of Tyndall on the core finding and five years ahead on the climate implication, since those numbers, established through careful historical research rather than assumed, are what turned a sympathetic anecdote into a documented priority claim. Readers should not expect Foote’s simple apparatus to have produced Tyndall’s level of precision; her contribution is significant for being directionally right and early, not for being the most detailed account available. As a corrective to a settled origin story, and as science in its own right, it holds up well on both counts.