Few people know, but once oxygen almost destroyed all life on the Earth. Its excessive amount led to the so-called oxygen catastrophe and caused the largest ice age - the Huronian glaciation. RBC-Ukraine tells what is known about Snowball Earth, the oxygen catastrophe, the Huronian glaciation, and the mass extinction of all living things on the planet.
Sources used during preparation of the material: Big Think, Wikipedia.
What's Snowball Earth
Snowball Earth is a hypothesis suggesting that our planet could have been completely covered in ice about 720-542 million years ago \- during various periods of the Neoproterozoic era, or in other geological epochs.
This hypothesis arose to explain the deposition of glacial sediments in tropical latitudes during the Cryogenian period (850-630 million years ago) and other mysterious nuances of this period.
The theoretical justification for the hypothesis was provided in the 1950s by the Soviet climatologist and geophysicist Mikhail Budik.
According to another scientist, Paul Hoffman, during that period Earth could have turned into a solid snowball because the average temperature on the planet dropped to minus 45 degrees Celsius, and the ice covered the entire Earth with a thickness of up to 1.5 km.
Antarctic ice sheet (photo: uk.wikipedia.org)
How the oxygen catastrophe happened
For a long time, scientists tried to explain the origin of glaciers in the most unexpected places on our planet.
Later, researchers found out that thereason could have been oceanic cyanobacteria \- blue-green algae that obtain the energy necessary for existence through photosynthesis.
According to scientists, our planet formed over 4.5 billion years ago, and life on it first appeared several hundred million years later. Later - about 2.7 billion years ago - cyanobacteria began to produce oxygen abundantly, which accumulated in the atmosphere for hundreds of millions of years.
Initially, the oxygen released by cyanobacteria combined with iron, and the atmosphere did not change. However, over time, most of the free iron oxidized, and oxygen became a destroyer.
Then the Earth's atmosphere consisted mainly of carbon dioxide gas, but with the appearance of cyanobacteria, the composition of the atmosphere underwent radical changes.
Oxygen molecules destroyed methane in the Earth's atmosphere, which trapped heat and created a greenhouse effect. As a result, global temperatures began to significantly decrease.
Since the energy of the Sun at that time was much less than it is now, methane was almost the only factor that maintained warmth on our planet.
Based on this, about 2.5-2.0 billion years ago, the so-called oxygen catastrophe occurred on Earth - a radical change in the environment.
Clouds in the lower atmosphere of Earth (photo: en.wikipedia.org)
Huronian glaciation and the death of living organisms
The oxygen catastrophe on Earth led to the Huronian glaciation \- one of the oldest and longest ice ages in the geological history of our planet, which lasted about 300 million years.
At the same time, oxygen, actively produced by cyanobacteria, destroyed most other forms of life \- anaerobic organisms - which did not use oxygen because it was toxic to them.
The powerful glaciation caused the extinction of the cyanobacteria themselves. Fortunately, the chain of life on the planet did not break at that time (it partially survived deep underwater and in the earth's crust).
Populations of a few surviving organisms were forced to evolve in different directions. This led to the emergence of more complex organisms that had a better chance of survival.
At that time, the Earth had practically turned into a huge snowball, but the amount of carbon dioxide in the atmosphere began to recover, which again caused a greenhouse effect.
Researchers suggest that this could have happened against the backdrop of Earth's volcanic activity.
After the end of this glacial period, the first eukaryotic cells appeared on the planet. They were the ones who gave rise to all the existing plants, fungi, and animals.
Based on this, some researchers argue that humanity would never have emerged if oxygen had not destroyed the methane-rich atmosphere of the Earth and had not allowed the first living cells to develop in a new direction.
At the same time, one should not forget that about 2.5 billion years ago, the largest mass extinction in the Earth's history occurred.
Earlier we reported that a new "Ring of Fire" may appear on Earth, threatening one of the oceans.
Read also about the main predator of Antarctica that existed 50 million years ago.