| Summary: | The fact that carbon dioxide is a 'greenhouse gas' - a gas that prevents a certain amount of heat radiation escaping back to space and thus maintains a generally warm climate on Earth, goes back to an idea that was first conceived, though not specifically with respect to CO2, nearly 200 years ago. The story of how this important physical property was discovered, how its role in the geological past was evaluated and how we came to understand that its increased concentration, via fossil fuel burning, would adversely affect our future, covers about two centuries of enquiry, discovery, innovation and problem-solving.This version (June 2020) supercedes the original April 2013 article, since a lot more has come to light about the work done in the 1850s-early 1860s and the important role of Eunice Foote. Katharine Hayhoe is particularly thanked for helpful discussions on that topic.For larger versions of all timeline graphics, please click on them (they will each appear in new browser windows Climate Science - the complete timeline, created by jg. Click on graphic for larger version. To pick up the scientific trail of what is today known as the Greenhouse Effect, we need to travel back in time to France in the 1820s. Napoleon, defeated at the Battle of Waterloo a few years previously, had just died. A scientist, who had formerly undertaken significant engineering and academic projects for the late Emperor, was now busily engaged on his investigations of the physical world. He had a specific interest in the behaviour of heat. This was Jean Baptiste Joseph Fourier (1768–1830).Fourier had calculated that a planetary object the size of Earth should, quite simply, not be as warm as it is, at its distance from the Sun. He knew that distance, since it had been calculated using a combination of observations of the passage of Venus across the Solar disc and trigonometry, in the 1770s. The value obtained was remarkably close to modern measurements – 149... |