Science Daily: There are new findings regarding a phase of rapid global greenhouse warming that took place 55 million years ago. This period of climate change is regarded as the best fossil analogue to current and future greenhouse warming. Analogous to the Earth’s current situation, greenhouse warming 55 million years ago was caused by a relatively rapid increase of CO2 concentrations in the atmosphere. This phase, known as the Paleocene-Eocene thermal maximum (PETM), was studied using sediments …