Oxygen atmosphere on Earth found millions of years earlier than thought

William Atkins
Monday, 01 October 2007 20:33

Science - Climate

The Great Oxidation Event was a global environmental change that was believed to have occurred about 2.4 billion years ago—when oxygen was first believed to show up and rapidly accumulate in the Earth’s atmosphere. Recent research shows that oxygen, instead, appeared millions of years earlier.       

Scientists analyzed a lengthy rock core in the Hamersley Basin located in western Australia to find that oxygen was present in Earth’s atmosphere above 50 to 100 million years before the Great Oxidation Event, sometimes also called the Oxygen Catastrophe, Oxygen Revolution, and other such names.

Previous to the presence of oxygen, methane and ammonia were the main ingredients of the atmosphere. Currently, nitrogen makes up about 78% of the Earth’s atmosphere, followed by oxygen at 21%, argon at less than 1%, carbon dioxide at about 0.04%, and trace amounts of other gases and water vapor.

The result of the researchers’ work was found in the Friday, September 28, 2007 issue of Science. The team was headed by earth and space exploration professor Ariel Anbar, Arizona State University, and geochemistry professor Alan Jay, University of Maryland.

Anbar commented on the discovery, “We seem to have captured a piece of time before the Great Oxidation Event during which the amount of oxygen was actually changing – caught in the act, as it were.”

Further information about the study appears at in the article “Researchers detect hint of oxygen 50 to 100 million years earlier than first believed” at http://www.eurekalert.org/pub_releases/2007-09/asu-rdh092007.php.

Scientists wish to know more about these time periods in Earth’s distant past so they can explain why life-giving oxygen suddenly became more prevalent in the Earth’s atmosphere and to learn more about how Earth evolved over billions of years of time. Examination of the Earth shows scientists that our planet is about 4.56 billion years old.