Women in climate science: what did Eunice Foote discover?

Eunice Newton Foote was born in the United States in 1819. Her parents were Thirza Newton and Isaac Newton, a farmer, entrepreneur and distant relative of his renowned namesake. At 15, Eunice spent a year at the Troy Female Seminary, a preparatory day and boarding school for women in New York. There, she was educated by Amos Eaton, a botanist, geologist and education radical who popularized then cutting-edge techniques like learning by doing.

As part of their studies, pupils at the Troy Female Seminary were allowed to attend classes and lectures at nearby colleges. It was at one of these neighboring institutions that Eunice was first introduced to the subjects of chemistry and biology, and the influential work of Almira Hart Lincoln Phelps, the third woman ever elected to the American Association for the Advancement of Science.

The scientific interest Foote had fanned at the Seminary stayed with her for many years. But, being denied access to scientific establishments because of her sex, she was forced to pursue her passion as an amatuer; a ‘natural philosopher’, as it was referred to at the time.

Foote’s most famous experiment - which cemented her albeit unappreciated legacy as a climate change pioneer - explored how atmospheric gasses interact with sunlight. It worked like this: using an air-pump, she filled two twenty-inch glass tubes - each one fitted with two thermometers - with oxygen, damp or dry air, or carbon dioxide. One tube would contain one gas, while the other either would hold either the same gas as a control, or another that contained a different amount of moisture, or had a different density. Once the contents of both tubes reached the same temperature, Foote would put both tubes in direct sunlight or one in the shade. Finally, she would record the temperature readouts from the thermometers over time.

Foote’s findings were groundbreaking. She found that moist air could hold more heat than dry air, and that, crucially, carbon dioxide trapped more of the sun’s heat than any other gas she tested. Summarizing her work, Foote wrote: “The receiver containing this gas became itself much heated—very sensibly more so than the other—and on being removed [from the Sun], it was many times as long in cooling.” In essence, Foote had principally identified the properties that make CO2 such a prolific ‘greenhouse gas’.

More astonishing still was in the novel insight she reached regarding carbon dioxide and the atmosphere, the ramifications of which are now scrutinized by satellites, supercomputers and scores of scientists across the globe: “An atmosphere of that gas would give to our earth a high temperature; and if as some suppose, at one period of its history the air had mixed with it a larger proportion than at present, an increased temperature... must have necessarily resulted.”

In other words, Foote had realized that higher amounts of carbon dioxide in the Earth’s atmosphere would lead to global warming.

In 1856, Foote captured her findings in her debut paper, Circumstances affecting the Heat of the Sun’s Rays. The same year, Foote’s work was presented to the Annual Meeting of the American Association for the Advancement of Science. Not by Foote, but her male colleague, John Henry. In the 1857 edition of Scientific Discovery, David A. Wells reported that Henry had prefaced Foote’s paper, “with a few words, to the effect 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.”

Though Foote’s paper received some initial attention, it was soon forgotten and, like its author, quickly faded into obscurity. Three years after she had published her paper, Irish physicist John Tyndall demonstrated that water vapor and atmospheric gasses absorbed and emitted infrared energy, the mechanism by which carbon dioxide traps solar radiation in the planet’s atmosphere and the cause for the greenhouse effect.

It is not known whether Tyndall was aware of Foote’s research while he was contemplating his own. But what is beyond conjecture is that while Tyndall was, in most circles, credited as the first person to identify this important relationship and has long been celebrated as one of the early and most significant progenitors of climate science.

Foote published her second and final scientific paper, On a new source of electrical excitation in 1857, before her interest shifted to campaigning for women’s rights and invention. Hers are the only two physics papers published by an American woman before 1889.

It is only within the last decade - more than 150 years after she published her paper on the interplay between solar radiation and CO2 - that Eunice Foote has begun to receive recognition for her contributions.

As the National Oceanic and Atmospheric Administration rightly highlights, “Foote is among the pioneers whose work paved the way toward acceptance.” Her story stands as a powerful reminder that more work must be done to unearth the many sidestepped contributions of women scientists, engineers, mathematicians have made throughout the centuries.

Of Reuter’s list of the 1,000 most influential climate scientists, less than one in seven were women. Supporting women climate scientists, like Eunice Foote, and highlighting their achievements is not only a moral imperative, it is a global necessity. To climate-align decisions on every built and natural asset, we need to cultivate scientific talent across the board. This talent must be drawn from around the world, ensuring that all countries affected by climate change contribute to the debate, not just wealthier nations.

This is why the mission of the International Day of Women and Girls in Science is so important. We are proud to contribute to it. Visit our women in climate science hub to discover more resources about supporting women in climate science.