Imagine figuring out something about the future over a hundred years before anyone else believed you. That is what Svante Arrhenius did. Born on March 19, 1859, in Sweden, Arrhenius was a brilliant chemist who asked a simple question: what would happen if the amount of carbon dioxide in the air changed? In 1896, he calculated that doubling the carbon dioxide in Earth's atmosphere would raise the planet's temperature by about five degrees Celsius. He spent months doing the math by hand, without a computer. His idea was based on the greenhouse effect. Just like glass walls trap heat inside a greenhouse, certain gases in the atmosphere trap heat from the sun. Carbon dioxide is one of those gases. Without the greenhouse effect, Earth would be a frozen, lifeless world. Arrhenius thought a warmer Earth might be good for people. He imagined longer growing seasons and more food. He did not predict that burning coal and oil would add carbon dioxide so quickly. Today, scientists know that too much greenhouse gas causes serious problems. Arrhenius also won the Nobel Prize in Chemistry in 1903 for work about how electricity moves through liquids.