Deep freeze: ice ages have released the oxygen necessary for life

Ice ages have released the oxygen necessary for life

Two and a half billion years ago, the Earth was an inhospitable place. The planet was hostile to the manifestation of the complex life forms that exist today. Its main inhabitants were bacteria - cyanobacteria. They slowly changed the world around them through photosynthesis. There was not enough oxygen in the atmosphere of the early Earth. The changes began to occur during the period that scientists gave the name GOE - the Great Oxidizing Event.

It was a period of chemical change. They are observed in soil strata, in rocks that's age is 2.5 billion years. These changes have led to the release of a large volume of oxygen that is important for life. The process was carried out using cyanobacteria.

Their groups lived in water and were found in rocky formations called stromatolites. Science believes that a series of glaciations on our planet was associated with GOE. The first occurred about 2.42 billion years ago and was so strong that ice sheets stretched from the poles of the planet to the tropics. But the exact time of that period is unknown, and therefore scientists asked the question - was it glaciation or oxidation?

Many hypotheses supported both scenarios. Glaciation could have occurred earlier, and then the nutrients that formed the glaciers gradually drained into the oceans during the melting of ice sheets, causing cyanobacteria to bloom and thereby increase oxygen production. The second scenario could lead to a violation of the level of greenhouse gases.

Science has an evidence that it had high concentrations in the early atmosphere of the planet. A decrease in methane would lead to a drastic change in climate, a cold snap would occur on the planet. To obtain more accurate data, the NASA experts studied rock core samples from the Kola Peninsula.

Sedimentary rocks formed about 2.5 billion years ago. They contained sulfur and its analysis showed that the atmosphere of that period was deficient in oxygen. The scientists believe that in that way they managed to find more convincing evidence of the fact that GOE occurred on the planet between 2.5 and 2.43 billion years ago, which is consistent with the state of sulfur isotopes not only on the Kola Peninsula, but also in South Africa, North America and Australia.

It means that an increase in oxygen concentration in the planet’s atmosphere could lower methane levels and weaken the greenhouse effect. Thus, the Earth was on the verge of severe glaciation.