PARIS: Scientists believe that Earth’s first atmosphere, formed after its creation, was probably made up of hydrogen and helium.
Earth’s oxygen-laden atmosphere gradually emerged about 2.5 billion years ago in whiffs from a type of blue-green algae in shallow seas, says a team of scientists from Canada and the United States. The team presents new isotopic data showing that a burst of oxygen production by photosynthetic cyanobacteria temporarily increased oxygen concentrations in Earth’s atmosphere.
The new data suggest that O2 levels in the Earth’s atmosphere fluctuated until enough O2 finally accumulated to create a permanently oxygenated atmosphere around 2.4 billion years ago, a transition widely known as the “Great Oxidation Event”.
Brian Kendall of the University of Waterloo, suggested that beginning of oxygenation of Earth’s surface was a highly complex process which was characterized by multiple whiffs of oxygen until a threshold point was reached.
