In the summer of 1856, working with simple equipment, Eunice Newton Foote set thermometers inside glass cylinders, filled them with different gases and placed them in sunlight. The cylinder containing carbon dioxide became hotter than the one containing ordinary air and stayed warm longer after it was removed from the sun.
Foote described the work in a two-page paper titled Circumstances Affecting the Heat of the Sun’s Rays. Modern histories of physics recognize her 1856 experiment as an extraordinarily early demonstration connecting carbon dioxide with a warmer atmosphere. Her apparatus did not directly isolate the infrared mechanism behind the greenhouse effect, but her climate inference came before John Tyndall’s more sophisticated experiments on radiant heat.
The experiment itself was almost embarrassingly simple
Foote used glass cylinders, thermometers and an air pump. Across a series of trials she compared gases and mixtures including common air, moist and dry air, carbon dioxide, oxygen and hydrogen. Carbon dioxide produced the strongest heating in sunlight and remained warm longer after the cylinder was removed from direct exposure.
Her most important step was the inference she drew from those measurements. Foote proposed that an atmosphere containing more carbon dioxide would produce a warmer Earth, and she suggested that higher concentrations in the geological past could help explain warmer climates. It was an exceptionally early experimental connection between atmospheric composition and planetary temperature.
That is not quite the same as predicting modern human-caused global warming. Foote did not connect rising carbon dioxide to industrial fossil-fuel emissions. What she established was the earlier physical insight on which that later understanding would build.
Who Eunice Newton Foote was
Foote was born in Connecticut in 1819 and grew up in New York. She attended Troy Female Seminary, where students received unusually broad academic instruction for women of the period and could take practical science courses in laboratories at the nearby Rensselaer School, the institution that later became Rensselaer Polytechnic Institute.
In 1841 she married Elisha Foote, a lawyer, judge, inventor and fellow experimenter. The couple lived in Seneca Falls and became friends of Elizabeth Cady Stanton. Eunice and Elisha both signed the Declaration of Sentiments produced by the 1848 Seneca Falls Convention, and Eunice later secured patents for inventions of her own.
Then came the cylinders.
Why a man read her paper aloud
At the American Association for the Advancement of Science meeting in Albany in August 1856, Smithsonian secretary Joseph Henry read Foote’s paper. The surviving record does not establish exactly why Foote did not deliver it herself. Women rarely presented scientific work at meetings of the period, but the AAAS constitution did not explicitly prohibit them from doing so.
Henry’s presentation was not recorded in the official meeting proceedings. Foote’s paper itself was nevertheless published later that year in the American Journal of Science and Arts, immediately after a paper by her husband and under Eunice Foote’s own name.
No verified portrait of Eunice Foote is known to survive.
Tyndall’s independent — and more precise — version
By 1859, Irish physicist John Tyndall was using sophisticated custom apparatus to investigate how gases absorbed radiant heat. His laboratory work identified water vapor, carbon dioxide and other gases as absorbers of heat radiation, providing a much more direct experimental account of the mechanism now associated with the greenhouse effect.
Tyndall’s measurements were more precise, his equipment was purpose-built for radiant-heat experiments and his institutional platform at the Royal Institution was far larger. His preliminary results appeared in 1859, with his major Royal Society paper following in 1861.
Tyndall did not cite Foote. Historians have examined whether he could have encountered her work through the scientific literature, but there is no evidence that he read her paper. The safest conclusion is that the two reached related findings independently, while Tyndall’s technically stronger work became part of the scientific canon and Foote’s earlier experiment largely disappeared from it.
How she was pulled back out of the archives
Foote was not completely forgotten, but the climate significance of her experiment received little attention for generations. In 2011, retired petroleum geologist Raymond Sorenson published an article drawing renewed attention to her after encountering an account of the work in an old volume of the Annual of Scientific Discovery.
The reassessment has continued. In early 2026, Publishers Weekly highlighted three new books for younger readers: Jen Bryant’s Foote Was First!, Rebecca Donnelly’s Change Is in the Air, and Lindsay H. Metcalf’s novel in verse Footeprint.
The American Institute of Physics has documented the same historical shift, describing Foote’s journey from “Foote-note” to climate science founder.
What the physics actually showed
Foote’s cylinders demonstrated that gases exposed to sunlight could warm by different amounts, with carbon dioxide producing the strongest heating in her trials. But the experiment did not cleanly separate the different pathways by which energy entered, left and circulated through the glass apparatus.
That distinction matters because the atmospheric greenhouse effect is fundamentally about outgoing infrared radiation. Most incoming visible sunlight passes through the atmosphere and warms Earth’s surface. The warmed surface emits infrared radiation, and gases including carbon dioxide absorb and re-emit part of that outgoing energy.
Tyndall’s later apparatus directly investigated radiant heat and therefore supplied the stronger mechanistic experiment. Foote reached the climate-relevant conclusion first without having the equipment needed to establish precisely why the gases behaved as they did.
Foote’s second paper — often forgotten twice
Foote published another physics paper in 1857, On a New Source of Electrical Excitation, dealing with static electricity under different atmospheric conditions. She also held three patents and remained active in the women’s-rights movement.
She died in 1888. By then, her brief contribution to the emerging science of atmospheric warming had already slipped from the standard scientific narrative.
A pattern that keeps recurring in the history of science
Scientific history contains other cases where later retellings compress complicated collaborations into simpler stories of individual discovery. DNA’s famous Photo 51 is one example: Raymond Gosling took the photograph while working with Rosalind Franklin, whose X-ray diffraction research was critical to understanding DNA’s structure.
The science of carbon dioxide also kept advancing. In 1938, Guy Stewart Callendar published an analysis linking fossil-fuel carbon dioxide with rising temperatures. By 1965, President Lyndon Johnson’s Science Advisory Committee was formally warning about the atmospheric buildup of carbon dioxide from fossil-fuel combustion.
The problem Foote had touched with glass cylinders had become a central question in atmospheric science. Today’s energy transition — across wind, solar, hydro, nuclear power, storage and efficiency — is partly an attempt to change the systems that continue adding heat-trapping gases to the atmosphere.
The number she couldn’t yet see
Foote could not have imagined the scale industrial emissions would eventually reach. Global Carbon Budget 2025 estimates cumulative anthropogenic carbon dioxide emissions from 1850 through 2024 at about 2.73 trillion tonnes, counting fossil-fuel and industrial emissions together with land-use change. The same assessment puts atmospheric carbon dioxide at 425.6 parts per million in 2025, compared with roughly 278 ppm before industrialization.
What Foote knew was narrower and, in hindsight, remarkable: carbon dioxide behaved differently from ordinary air in her experiment, and changing its abundance could change Earth’s temperature. Time revisited that overlooked contribution in 2019, noting that Foote had connected atmospheric carbon dioxide with Earth’s temperature as early as 1856.
Historians are still looking for a verified image of Eunice Foote. Her cylinders were emptied a long time ago. The physics behind the question she raised is still running.
