Woman Who Linked CO2 With Climate Change in 1856

Eunice Foote discovered that carbon dioxide absorbs heat, and theorized that if the Earth’s air filled with more CO2, the planet’s temperature would rise. was an American scientist, an inventor, and a women's rights campaigner from Seneca Falls, New York.

The year was 1856. Foote’s brief scientific paper was the first to describe the extraordinary power of carbon dioxide gas to absorb heat - the driving force of global warming. Carbon dioxide is an odorless, tasteless, transparent gas that forms when people burn fuels, including coal, oil, gasoline, and wood.

As Earth’s surface heats, one might think that the heat would just radiate back into space. But, it’s not that simple. The atmosphere stays hotter than expected mainly due to greenhouse gases such as carbon dioxide, methane, and atmospheric water vapor, which all absorb outgoing heat. They’re called “greenhouse gases” because, not unlike the glass of a greenhouse, they trap heat in Earth’s atmosphere and radiate it back to the planet’s surface. The idea that the atmosphere trapped heat was known, but the cause wasn’t.

Foote conducted a simple experiment. She put a thermometer in each of two glass cylinders, pumped carbon dioxide gas into one and air into the other and set the cylinders in the Sun. The cylinder containing carbon dioxide got much hotter than the one with air, and Foote realized that carbon dioxide would strongly absorb heat in the atmosphere.

Foote’s discovery of the high heat absorption of carbon dioxide gas led her to conclude that “if the air had mixed with it a higher proportion of carbon dioxide than at present, an increased temperature” would result.

A few years later, in 1861, the Irish scientist John Tyndall also measured the heat absorption of carbon dioxide and was so surprised that something “so transparent to light” could so strongly absorb heat that he “made several hundred experiments with this single substance.”

Tyndall also recognized the possible effects on the climate, saying “every variation” of water vapor or carbon dioxide “must produce a change of climate.” He also noted the contribution other hydrocarbon gases, such as methane, could make to climate change, writing that “an almost inappreciable addition” of gases like methane would have “great effects on climate.”

The first quantitative estimate of carbon dioxide-induced climate change was made by Svante Arrhenius, a Swedish scientist and Nobel laureate. In 1896, he calculated that “the temperature in the Arctic regions would rise 8 or 9 degrees Celsius if carbon dioxide increased to 2.5 or 3 times” its level at that time.

Nils Ekholm, a Swedish meteorologist, agreed, writing in 1901 that “the present burning of pit coal is so great that if it continues . . . it must undoubtedly cause a very obvious rise in the mean temperature of the earth.”