The Off-Key Bard
History

This Day in History — Eunice Foote Demonstrates the Heat-Trapping Power of Carbon Dioxide

On this day in 1856

On August 23, 1856, a man read Eunice Foote's paper for her at the AAAS — and her link between CO2 and planetary warming sat unrecognized for 155 years.

The Off-Key Bard sets two glass cylinders beneath the Sun and watches the thermometers rise, as a remarkably simple experiment reveals something profound about Earth's atmosphere…

"Sometimes an experiment doesn't need an enormous laboratory. Sometimes two cylinders, a few thermometers, and sunlight are enough to glimpse how an entire planet works."

On this day in 1856, at the annual meeting of the American Association for the Advancement of Science in Albany, New York, Smithsonian Institution Secretary Joseph Henry rose to present a paper. He introduced the work by declaring that science was "of no country and of no sex. The sphere of woman embraces not only the beautiful and the useful, but the true." Then he read out the findings — because the woman who had done the research, Eunice Newton Foote, was not permitted to present her own work at the meeting.

Foote had been born in 1819 in Bloomfield, New York, a distant relative of the mathematician Isaac Newton. She attended the Troy Female Seminary, where founder Emma Willard believed in educating women in every subject, including the sciences then considered exclusively male territory. By 1848, Foote was active enough in the women's rights movement that she had signed the Declaration of Sentiments at Seneca Falls, appearing on the same document as her friend Elizabeth Cady Stanton. She was, by any measure, an amateur scientist in the most serious sense of the word.

The experiment she designed was elegantly simple. She took two glass cylinders, each equipped with thermometers, and systematically compared how different gases heated up and cooled down under direct sunlight. Moist air heated more than dry air. But what she observed with carbon dioxide — which she called "carbonic acid gas" — stopped her:

The CO2-filled cylinder reached 125°F (52°C) in sunlight — significantly hotter than ordinary air. More striking still, when she moved the cylinder into shade, it took far longer to cool down than air did. The gas was not just absorbing heat; it was holding it.

Her conclusion, stated plainly at the end of her short paper, was among the most prescient sentences written in American science in the nineteenth century: "An atmosphere of that gas would give to our earth a high temperature."

What Henry Did With It

Despite his generous introduction, Henry did not champion the finding. When the New York Daily Tribune reported on the meeting, it quoted Henry saying that while Foote's experiments were "interesting and valuable," there were "difficulties encompassing any attempt to interpret their significance." He noted them and moved on. Her paper was excluded from the official AAAS conference proceedings entirely — though it was published later that year in the American Journal of Science and Arts under her own name, immediately following a longer paper by her husband Elisha on a related topic.

She presented her own research at the following year's AAAS meeting, on static electricity. Then she stopped publishing science. She later filed patents for a rubber sole designed to silence squeaking shoes and a paper-making machine, and died in 1888.

The Tyndall Question

Three years after Foote's paper, Irish physicist John Tyndall published the results of his own experiments on the heat-absorbing properties of atmospheric gases — more rigorous, better-equipped experiments using infrared radiation rather than visible sunlight. Tyndall is still widely credited as the person who first demonstrated the mechanism of the greenhouse effect, and the science community in the decades that followed credited him alone.

The relationship between the two lines of research is genuinely complicated. Foote measured warming from visible solar radiation. Tyndall's experiments measured infrared absorption — which is specifically the mechanism by which the greenhouse effect operates. Whether Tyndall was aware of Foote's work is unknown: he was on the editorial board of a journal that had republished a paper by Elisha Foote printed alongside Eunice's, and was known to hold low opinions of women's intellectual capacity. No reference to either Foote appears in any of his surviving correspondence or notes.

What is clear is that Eunice Foote reached the right conclusion three years before Tyndall, using simpler equipment — and that her work was presented by someone else, excluded from the official record, and forgotten.

The Rediscovery

In 2011, geologist Raymond Sorenson bought an old copy of David A. Wells's Annual of Scientific Discovery for 1856 — a privately published annual summary of that year's scientific proceedings. He found a short passage quoting Henry's AAAS remarks about a paper by "Mrs. Foote." Sorenson knew enough about the history of greenhouse gas research to recognize immediately what he was reading. He published a short paper identifying Foote as having anticipated Tyndall's conclusions by three years. The rediscovery generated international attention.

No known portrait of Eunice Newton Foote exists.

"Two cylinders beneath the Sun,
A quiet experiment begun…
Yet from the heat her instruments knew,
A glimpse of Earth's own future grew."

History reminds us: Eunice Foote did not create modern climate science in a single afternoon. But she was the first person to demonstrate in an experiment that carbon dioxide traps heat, and the first to state in writing that a planet with more of it in its atmosphere would be a warmer planet. That she sat in the audience while someone else read her findings to a room she wasn't permitted to address fully is, perhaps, the most complete summary possible of the world she was working in.

Sources

← Back to the Desk — History