A decrease in the amount of dissolved nickel in ocean waters beginning 2.7 billion years ago could have stifled methane-producing bacteria and set the scene for oxidation of the Earth’s atmosphere, researchers report in the April 9 Nature.
Billions of years ago, methane-producing bacteria called methanogens thrived in nickel-rich seas. The high amounts of methane that this early life pumped into the environment prevented oxygen accumulation in the atmosphere because the methane reacted with any oxygen, creating carbon dioxide and water, the researchers suggest.
But 2.4 billion years ago, the Earth’s atmosphere changed. Atmospheric methane levels decreased, allowing oxygen levels to increase in what scientists call “the Great Oxidation Event.” Researchers debate how these atmospheric changes occurred.