The clamour about the warming planet and the changing climate is growing louder by the day as we worry about the implications of greenhouse gases on the earth. But, did you know that our planet has seen many such ‘greenhouse periods’ in the past where the concentrations of greenhouse gases were significantly higher, resulting in higher temperatures? Yes, you read that right, and one such period was about 56 to 34 million years ago, called the Eocene epoch.