Scientists warn: Earth may undergo subversive transformation! Atmospheric oxygen levels return to 2.4 billion years ago

Today, the oxygen-rich atmosphere has shaped a blue planet like no other in the universe, and countless life is thriving on Earth. However, this atmospheric environment is not "the norm" on Earth. Imagine if there was a fundamental shift in the composition of Earth's atmosphere, would humans still exist? In fact, scientists have predicted that in the future, the Earth's atmosphere will return to a methane-rich, low-oxygen atmosphere, which will not only threaten the entire human civilization, but also put the entire planet's life at risk.

About 2.4 billion years ago, due to unknown reasons, the content of free oxygen in the Earth's atmosphere increased dramatically, and life on Earth has only begun to thrive since then. And a study published in the top journal "Nature Geoscience" shows that the earth's atmosphere will usher in a subversive transformation, which will bring the earth back to the state before the Great Oxidation Event (GOE) 2.4 billion years ago. There is no doubt that this is devastating for the vast majority of life.

To assess the impact of changing oxygen levels on life on Earth, the researchers conducted detailed modeling analyses of Earth's biosphere. The simulations showed that as the sun's brightness and heat radiated to Earth increased, the gas would be broken down more, resulting in a relative drop in atmospheric carbon dioxide levels. The reduction in carbon dioxide levels means that photosynthetic organisms are less able to operate efficiently, and ultimately the death of plants and the reduction of oxygen levels in the earth form a vicious circle. When oxygen levels drop, anaerobic methanogens will proliferate, and their expansion will trigger a dramatic rise in atmospheric methane levels.

Scientists had previously predicted that within the next 2 billion years, the increase in the intensity of solar radiation will cause the seawater on the Earth's surface to evaporate, making life impossible to survive. But a new study based on 400,000 simulations finds that the first drop in oxygen levels in the next billion years or so will directly trigger the loss of life on Earth.

Model projections suggest that Earth's oxygen-rich atmosphere will last only a billion years. The extreme drop in oxygen levels is likely to be triggered by humid greenhouse conditions in Earth's climate system, or before the massive loss of surface water. By then, the main features of Earth's atmosphere are elevated methane, low carbon dioxide, and the absence of ozone. Humans and the vast majority of life forms that rely on oxygen for life will come to an end, so figure out where the oxygen level is. Changes over the next billion years are critical.

However, climatologists also admitted that this "extreme climate change" may not occur for another billion years, but the key is that when the change begins, it will rapidly evolve towards "collapse". Geoscientist Chris Reinhard of the Georgia Institute of Technology warned that the drop in oxygen levels would have very, very extreme consequences that we cannot measure today.

The research is also relevant to the search for a "second Earth" beyond the solar system. Kazumi Ozaki, an environmental scientist at Toho University in Japan, found through statistical calculations that the oxygen-rich time span of the earth only accounts for 20-30% of the earth's lifespan. After the disappearance of higher organisms, microorganisms will once again dominate the earth.

Because sufficient oxygen content is not a necessary condition for a planet to be suitable for the reproduction of life, some planets may have oxygen in the past, but the oxygen content has dropped today, so the possibility of life cannot be ruled out. Future exploration of extraterrestrial habitable planets should not pay too much attention to oxygen content, and search for other biological characteristics is a more important task.