Volcanic CO2 Caused Ancient Episodes of Global Warming

[Climate Central]  In order to predict our climate future, scientists spend a lot of time looking into the past, trying to understand what conditions were like during times when the planet was much warmer or much cooler than it is today. The latest instance: a report published in the February issue of the journal Geosphere, offering a plausible explanation for swings between long stretches of greenhouse warming and dramatic cooling over millions of years.