What are the main mechanisms of climate regulation and climate change that have operated through Earth's history? The Earth's climate is regulated by a Carbon Dioxide thermostat that is the interaction between the Greenhouse Effect and the CO2 Cycle. I describe the CO2 cycle and its role in regulating global temperature. I will then discuss other influences on climate, and periods of glaciation (ice ages) in the recent and distant past, including the possible Snowball Earth events in the early and late Proterozoic Eon. Recorded live on 2009 Oct 8 in Room 1005 Smith Laboratory on the Columbus campus of The Ohio State University.