How to pronounce “vacillating” in English

Lots of volcanoes were going off, loading the environment with carbon, warming things up and eventually returning the carbon cycle to a more even keel.But that's how the carbon cycle works is it's always vacillating between these ice houses and these greenhouses.We couldn't probably have a Snowball Earth at this point because the sun is a bit warmer and it's unlikely we would have such as an intense runaway icehouse