Geophysicists from the United States and Australia concluded that 2.7 billion years ago, the Earth's atmosphere was much thinner, and the pressure in its lower layers was half the current. By now, the planet's gas envelope has increased significantly in size. The study is published in the journal Nature Geoscience and is briefly reported by the University of Washington.
Geophysicists have determined the atmospheric pressure at which gas bubbles formed in ancient lava flows. To do this, scientists used basalt samples found in the ancient Pilbara platform (craton) in western Australia, which arose as a result of volcanic activity approximately 2.7 billion years ago.
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Photo: Sanjoy Som / University of Washington
Scientists have estimated the size of gas bubbles formed at different depths of lava flows. Their diameter is related to the difference in atmospheric pressure at the base and upper layer of the lava flow. Scientists used these data to reconstruct the approximate distribution of atmospheric pressure on Earth 2.7 billion years ago.
About 2.7 billion years ago, the flow of solar energy was about 20 percent less than it is today, and the planet was inhabited by single-celled organisms. At the same time, life on Earth could arise, as scientists believe, about 3.8 billion years ago - 700 million years after its birth.
The planet's atmosphere 2.7 billion years ago contained less oxygen and nitrogen, and was also rich in carbon dioxide and methane. The latter connection made it possible to maintain the greenhouse effect in the Earth's gas envelope. Previously, scientists believed that to ensure it, the pressure at the base of the planet's atmosphere should have exceeded the modern ones by 1.6-2.4 times. New research refutes this view.
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