Scientists have long wondered what contributed to the climate changes that ended the ‘Snowball Earth’ era, and a recent study suggests that these changes were much more dramatic than once believed.

According to a report from ABC, scientists from the University of Southampton believe that underwater volcanism may have played a significant role in regulating the planet’s temperature roughly 700 million years ago.

The study, which was published in the journal Nature Geoscience, lends new insights into how the conditions on Earth first became suitable for life to develop millions of years later. According to co-author Professor Eelco Rohling from the Austalian National University, the planet may have stayed a frozen ball of ice were it not for a vast network of underwater volcanoes releasing heat from the center of the Earth.

Rohling and the study’s research team also suggest that underwater volcanism may have been responsible for starting the series of changes that led to the snowball Earth in the first place.

Traditionally, researchers believed that drainage from rivers into the ocean after the breakup of the supercontinent Rodinia changed the chemistry of the ocean, which led to a drastic drop in atmospheric carbon dioxide. Without any CO2 in the atmosphere to keep solar radiation from bouncing back into space, researchers think that the planet plunged into a deep freeze.

According to Professor Rohling, the network of underwater volcanoes is believed to have lifted the planet out of its snowball phase by adding much-needed CO2 into the atmosphere.

The recent study builds on current theories, suggesting that volcanic chemicals were more responsible for the massive drop in atmospheric CO2 than drainage from freshwater on land. The breakup of Rodinia led to a huge release of volcanic chemicals from the inside of the planet, precipitating a massive drop in CO2 that led to the ultimate freezing of the world.

The key evidence supporting this theory is the massive amounts of hyaloclastite, a volcanic rock abundantly distributed around continental borders. There must have been a significant amount of volcanic activity around the time of the Snowball Earth period, and researchers think this played a much larger role than once believed.

A press release from the University of Southampton describing the details of the study can be found here.