Earth's Climatic History. Climatologists have used various techniques and evidence to reconstruct a history of the Earth's past climate. From this data, they have found that during most of the Earth's history global temperatures were probably 8 to 15 degrees Celsius warmer than today. In the last billion years of climatic history, warmer conditions were broken by glacial periods starting at 925, 800, 680, 450, 330, and 2 million years before present.