Underwater Volcanoes Ended ‘Snowball Earth’ and Helped Start Animal Life

Underwater Volcanoes Ended ‘Snowball Earth’ and Helped Start Animal Life

The action of underwater volcanoes ended a phase in our planet’s history known as ‘Snowball Earth’ and it created the perfect conditions for the rise of animal life.

‘Snowball Earth’ took place about 720 to 640 million years ago when the surface of the planet became nearly entirely frozen for tens of millions of years. However, a new study – published Monday (Jan. 18) in the journal Natural Geoscience – stated that under the thick ice, erupting underwater volcanoes were creating new chemical reactions.

Dr. Thomas Gernon, lead author of the study and a Lecturer in Earth Science at the University of Southampton, School of Ocean and Earth Science, said that geoscientists have long wondered why and how the chemistry of the ocean changed when the ice melted.

In the new study, researchers at the University of Southampton wanted to answer those questions. The findings show that the explosive underwater volcanoes played an important part in Earth’s dramatic change.

A rapid warming of the planet – fuelled by greenhouse gas – occurred due to carbon emissions from the volcanic activity beneath the ice, the researchers found.

The breakup of the supercontinent Rodinia led to the formation of underwater ridges that extended for tens of thousands of kilometres. According to the researchers, Rodinia’s breakup also changed the chemistry of the oceans because river water began flowing into the ocean. The levels of carbon dioxide (CO2) in the atmosphere were also reduced.

Spewing lava reacted chemically with the icy ocean, releasing magnesium, calcium, silica, and phosphorus, the researchers said.

According to Dr. Gernon, although completely unexpected, new complex life forms took shape on Earth during this extreme climate phase.

The presence of oxygen in the oceans and in Earth’s atmosphere was the crucial element that enabled complex animals to evolve from single-celled organisms. The authors of the study wrote that before Snowball Earth, most living organisms were single-celled bacteria floating around in the sea.

Development of DNA and cell membranes was helped by the high phosphorus levels that oxygenated Earth’s oceans and atmosphere. Multicellular organisms (that consist of more than one cell), such as algae, began emerging in the waters, Dr. Gernon explained. The cyanobacteria and algae then produced oxygen through photosynthesis, which also aided the evolution of complex animal life.

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