Cosmic Dust Reveals Ancient Earth's Atmosphere Has The Same Amount Of Oxygen It Has Today

The researchers from Monash University have made a surprising discovery about the earth's atmosphere 2.7 billion years ago using the planet fossil micrometeorite or also known as space dust.

Science Daily reports that the study was printed in the journal Nature. The study was led by Dr. Andrew Tomkins, the lead author of the study, scientists from Australian Synchrotron and Imperial College, London and team of researchers from School of Earth, Atmosphere and Environment at Monash.

In the past study, it showed that the significant levels of oxygen gas built up in the atmosphere with the Great Oxidation Event. This happened about 2.4 billion years ago, according to Live Science. The event was caused by cyanobacteria, which are microbes like plants that photosynthesize and release oxygen. It was found out then that Earth's ancient atmosphere was poor in oxygen.

On the other hand, the new study suggests that the ancient Earth's upper atmosphere has the same amount of oxygen as today. Dr.Tomkins said that they used cutting-edge microscopes and discovered that most of the micrometeorites had once been particles of metallic iron that had been turned into iron oxide minerals in the upper atmosphere. This indicated a higher concentration of oxygen than expected.

He further explained that Earth at this time may have had a layered atmosphere with little vertical mixing and higher levels of oxygen in the upper atmosphere that was produced by the breakdown of CO2 by ultraviolet light.

Dr. Matthew Genge, a researcher from Imperial College said that the findings were surprising as it had been firmly established that the Earth's lower atmosphere was very poor in oxygen 2.7 billion years ago. He added that how the upper atmosphere could contain so much oxygen before the appearance of photosynthetic organisms was a real puzzle.