(Reuters) - A U.N. conference in Qatar next week is the latest attempt to combat global warming after mounting evidence that human activity is disrupting the climate. Here is a timeline of the road to action on global warming: 300 BC - Theophrastus, a student of the Greek philosopher Aristotle, documents that human activity can affect climate. He observes that drainage of marshes cools an area around Thessaly and that clearing of forests near Philippi warms the climate. 1896 - Sweden's Svante Arrhenius becomes the first to quantify carbon dioxide's role in keeping the planet warm. ...