The Earth was once a snowball! Chinese scientists reveal the mysteries of life evolution 600 million years ago
About 600 million years ago, the Earth twice became a "snowball Earth" with ice and snow up to kilometers thick on the ground, each lasting for over ten million years. What happened between two snowballs on Earth, and how did life come to life from nowhere?
Recently, the Shen Yan'an research group of the University of Science and Technology of China conducted systematic research in southern China and other regions, proposing for the first time new mechanisms of Earth and life evolution such as "ice melting induced large-scale volcanic eruptions", which has important implications for exploring modern extreme climate change and the livability of the Earth. On September 7th, the internationally renowned academic journal Science Progress published this research result.
Snowball Earth, also known as the global freezing phenomenon, has appeared multiple times in Earth's history. The Stuart Ice Age, which occurred about 720 million years ago, lasted for about 56 million years, and the Marino Ice Age, which occurred about 640 million years ago, lasted for over 10 million years. The millions of years of "frozen Earth" have not only brought silence, but also the great extinction of life on Earth.
Why does the Snowball Earth phenomenon occur? The mainstream view is that the seven continents currently on Earth were once connected as "supercontinents". Later, the supercontinents "cracked" and caused chemical weathering, consuming carbon dioxide in the atmosphere and causing a sharp drop in global temperatures, resulting in extreme ice ages.
Afterwards, the remaining volcanoes on Earth continued to be active for millions of years, releasing a large amount of carbon dioxide, forming a super greenhouse effect, leading to the melting of thick ice and snow on Earth. After the Stuart Ice Age, organisms such as green algae and sponges evolved on Earth.
The Shen Yan'an research group conducted research in multiple locations in southern China. They selected geological drilling systems up to 100 meters deep for analysis and found that during the early stage of ice and snow melting on Snowball Earth, the chemical composition of seawater was significantly different from modern seawater, with changes in mercury isotopes indicating increased volcanic activity. In response to this discovery, they proposed a new viewpoint that the rapid melting of ice and snow causes a sudden decrease in surface pressure on the Earth, leading to deep-seated magmatic activity and volcanic eruptions.
"Just like moving a giant rock from the ground, the previously suppressed underground magma suddenly erupts!" said Li Menghan, a member of the research group. The volcanic eruption induced by melting lasted for about 100000 years, driving a chain reaction in the Earth's environment.
Researchers have further discovered that the sulfur isotope composition of pyrite in geological sediments is abnormal, which is due to the Snowball Earth phenomenon changing the sulfur isotope composition of seawater sulfates.
Li Menghan said that these phenomena indicate that the oxygen content in the ocean and atmosphere gradually increased at that time, creating a favorable environment for the survival of life on Earth, promoting the gradual proliferation of green algae, and the emergence of primary animals such as sponges.
The researchers introduced that their research results have practical significance. "We are currently in a period of global warming, with some glaciers melting, which may also trigger volcanic eruptions and cause ocean hypoxia." Shen Yan'an said, all of these remind us to stay vigilant. The Earth's environment is a system, and a change may trigger a chain reaction.
