Extensive Underwater Volcanism Led to Snowball Earth: ANU Study Expedition 28

A new study shows how explosive underwater volcanoes may have pushed the Earth to become a “Snowball Earth,” a period when the Earth was frozen and buried in massive ice sheets with temperatures as low as -50°C. The results may also help explain how the planet got oxygen in the atmosphere and oceans, prompting the evolution of life.

Eelco Rohling, a professor from the Australian National University, explains that a Snowball Earth was an extreme event and it almost did not end. Experts believe that this was triggered by the breakup of a supercontinent called Rodinia.

This increased river flow into the ocean, changing the ocean chemistry and reduced atmospheric CO2 levels, which helps trap heat in the atmosphere. Subsequently, the global ice coverage also increased, turning Earth into a largely white and cold planet that reflected the sun’s energy rather than absorbing it.

Flickr/Christine Zenino

Flickr/Christine Zenino

The study, published in the journal Nature Geoscience, states that during this time, continental weathering stopped for millions of years until carbon dioxide from land volcanic activity warmed the atmosphere and melted the ice. The accumulation of carbon dioxide was effective in liberating the Earth from this situation. However, no weathering on the land surface happened and the sea ice prevented the ocean from taking up the carbon dioxide.

The researchers said that this may be one of the most extraordinary transitions from icehouse to greenhouse the Earth has ever experienced. Apparently, the evidence of this sudden shift can be seen as thick deposits or cap carbonates in places such as China and Namibia.

The explosion also produced massive amounts of hyaloclastite, a glassy pyroclastic rock. When these rocks piled up on the sea floor and reacted with the ocean, a huge amount of calcium, magnesium, silica and phosphorus were released.

The research team believed that the high phosphorus levels may have started the oxygenation of the atmosphere and the oceans, leading to the creation of life from one-celled bacteria in the ocean. Plus, this could have also encouraged the growth of algae and other multicellular organisms in the ocean.

The bacteria and algae may have also produced and released oxygen through photosynthesis. The team insists that their study prove that an extreme climate condition started life, despite popular beliefs that instances like this wipe out life completely.


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