There is still time, but in the distant future the sun will destroy almost all life on earth. This may have consequences for the search for extraterrestrial life.
In about a billion years, the sun will ensure that the earth’s atmosphere will lose almost all of its oxygen in a comparatively short time. Two researchers have determined this with a model of the further development of our atmosphere. Kazumi Ozaki and Christopher Reinhard are now presenting the result in the journal Nature Geoscience.
The comparatively high oxygen content of the earth’s atmosphere is therefore not permanent and depends on the behavior of our star. This should therefore also apply to distant exoplanets, which could possibly lose detectable oxygen again quickly.
Rapid end of the oxygen era
The researchers now explain that their biological, geological, chemical and climatic model have shown that our atmosphere will have more than one percent of its current oxygen content for about 1.08 billion years. Then there will be a “very, very extreme” waste, Reinhard explained to the US science magazine New Scientist : “We are talking about a million times less oxygen than today.” It will also happen rapidly, within just 10,000 years or so. Flora and fauna will not be able to adapt quickly enough and after that there will only be microbial life.
The main responsible for the rapid turnaround will therefore be the hotter sun, which emits more and more energy. This will reduce the amount of carbon dioxide in the atmosphere, as CO 2 absorbs the energy and then breaks up. At some point the proportion will be so low that photosynthesis is no longer possible, oxygen is no longer produced and the majority of all living things perish. It will be the opposite of the so-called Great Oxygen Disaster about 2.4 billion years ago. After that, only the most primitive creatures can survive again, as they existed before the sudden increase in oxygen levels.
While this predicted evolution is inconceivably far in the future, the researchers say it has an impact on our search for extraterrestrial life. Oxygen is an important biosignature , because because it is so closely related to life on earth, it is likely to be elsewhere as well. If it is detected in large quantities in an exoplanet, it could indicate life . The analysis now shows that the content in atmospheres is variable. So if no oxygen can be detected in a distant exoplanet, that does not mean that it did not exist there or could once exist. The two researchers therefore suggest that other elements could be better and, above all, more permanent biosignatures.