The story
Starting in 1859 the Irish physicist John Tyndall, at the Royal Institution in London, built a long metal tube to pass infrared radiation through different gases and measured how much arrived at the far end with a sensitive thermopile. Oxygen and nitrogen, which make up most of the air, were almost transparent to the heat. Water vapor, carbon dioxide, methane and ozone absorbed it strongly. He reported the results in 1861 and concluded that changes in water vapor or carbon dioxide could change climate, and wondered whether they might explain the ice ages. The American scientist Eunice Foote had reported in 1856 that jars of carbon dioxide warmed more in sunlight, but her experiment drew little notice.
In the 1820s Joseph Fourier had argued that the atmosphere keeps the Earth warmer than bare rock would be, without knowing how. Tyndall supplied a measurable mechanism, relying on the new understanding of heat as a form of energy. His results became the foundation for Svante Arrhenius's 1896 calculation of what extra carbon dioxide would do. The common name greenhouse effect is a loose analogy, since a glass greenhouse warms mainly by blocking air movement, but the physics Tyndall measured is real: gases that absorb infrared slow the escape of heat from the planet.
Why it mattered
- Arrhenius used Tyndall's absorption data in 1896 to estimate warming from carbon dioxide.
- Laboratory measurements of infrared absorption became the base of modern radiation physics used in climate models.
- The idea that small amounts of trace gases control Earth's temperature entered science long before it became a policy question.
Sources
- John Tyndall NASA Earth Observatory
- Foote vs Tyndall (high school resource) American Institute of Physics
- John Tyndall Britannica
Community notes
Loading notes…