The exact rate of sea-level rise during the period when "Snowball Earth" was transitioning to a more temperate climate is a topic of ongoing research and debate among scientists. There isn't a fixed or universally accepted figure for how much sea levels rose every decade during this transition. The concept of Snowball Earth refers to a time in Earth's history when the planet was almost entirely covered in ice, and the subsequent melting and recovery is a complex geological process that likely occurred over millions of years. If you're interested in specific figures, you would need to refer to the latest scientific research on this topic.