The Woman Who Discovered the Greenhouse Effect

The Mechanism

Eunice Newton Foote was born in 1819 in Goshen, Connecticut, a distant cousin of Sir Isaac Newton's American descendants. She studied science at the Troy Female Seminary in New York, one of the few American schools at the time that gave women a serious technical education. After marrying patent lawyer Elisha Foote, she settled in Seneca Falls, New York, where in 1848 she helped found the American women's rights movement by signing the Declaration of Sentiments. In the mid-1850s, in a laboratory she built at home, she began running experiments on heat and gases.

Her apparatus was deliberately simple. Two identical brass cylinders, each four inches across and about thirty inches long, were fitted with mercury thermometers and small stopcocks for filling. She filled the cylinders with different gases - moist air, dry air, hydrogen, oxygen, and carbon dioxide - placed them side by side in the August sun, and recorded how fast and how hot each one became. The carbon dioxide cylinder warmed to 125 degrees Fahrenheit while the ordinary air cylinder warmed to 100 degrees. When she brought both cylinders into the shade, the carbon dioxide cylinder cooled much more slowly than the air cylinder. The gas was not just absorbing sunlight faster - it was holding onto heat. Foote's paper ended with one of the most consequential sentences in the history of climate science: an atmosphere of that gas would give to our earth a high temperature.

The paper was presented at the eighth annual meeting of the American Association for the Advancement of Science (AAAS) in Albany, New York, on August 23, 1856. Women were not, at the time, allowed to read papers at scientific meetings. The paper was read on Foote's behalf by Joseph Henry, the first Secretary of the Smithsonian Institution and the most senior American physicist of the era. Scientific American covered the meeting in its September 13, 1856 issue, naming Foote as the author of the experiment.

Three years later, in 1859, the Irish physicist John Tyndall published a much more detailed quantitative study of how atmospheric gases absorb heat, using a far more sophisticated instrument he had designed himself. Tyndall's work was technically more refined and underpins all later climate physics. But Tyndall, in his 1859 paper and in everything he wrote afterward, never cited Foote. Throughout the twentieth century, textbooks credited the discovery of the greenhouse effect to Tyndall alone.

Foote's paper was rediscovered in 2010 by independent researcher Raymond Sorenson, working in the American Association of Petroleum Geologists' history-of-science magazine. Beginning in 2018, after careful reconstructions of her apparatus at universities in California and at the Royal Society of London, Foote was widely re-credited as the first experimental demonstrator of the greenhouse effect on a laboratory scale. A 2022 Royal Society paper exactly replicated her experiment with mid-19th-century brassware and confirmed her measurements to within the uncertainties she herself stated.

Foote died in 1888 at age 69. She lived long enough to see the women's rights movement she had helped found, but she did not live to see her name returned to the climate-science record. The gas she measured in a brass cylinder in her front yard in 1856 is now the central regulatory variable of every climate model on Earth.