"The ocean today is much more stratified - you have warm, buoyant water on top and cold, dense water on the bottom, and it resists mixing, although it does mix because of tides and winds," Schrag said. "In the snowball ocean, everything almost has the same density, so it takes much less energy to mix the oceans, and it turns out to mix very well."
In addition, powerful currents would have wrapped around the equator, and strong upwelling would have existed along the coasts. Unstable flows at the equator would have caused eddies that in turn would have generated jet streams reminiscent of those seen in the atmosphere of Jupiter, the researchers added. This circulation, including that of warm water, suggests melting rates near continents may have been as much as 10 times larger than previously estimated.
"You really have to think about Snowball Earth as being like a different planet," Schrag told OurAmazingPlanet. "Some criticisms people have made about the Snowball Earth hypothesis are based on assumptions of how the Earth worked that depend on how Earth works today. I think these findings are another nice example of how Snowball Earth was a very different planet, even though it's this planet. When you cover Earth with ice for so long, it changes many things you think are fundamental, including ocean circulation."