Earth could run out of oxygen in the future — and much sooner than previously thought. The oxygen-rich atmosphere that supports complex life could disappear in as little as a billion years, according to a new study. That would make the planet uninhabitable for most known life forms.
This is reported by BBC Sky at Night Magazine , citing joint work by scientists from Japan and the USA.
A team of researchers led by Toho University associate professor Kazumi Ozaki and Christopher Reinhardt of the Georgia Institute of Technology created a sophisticated computer model to analyze the planet's climate and biochemical processes. The goal was to find out when Earth's atmosphere would no longer support high levels of oxygen.
Based on the results of more than 400,000 simulations, scientists have concluded that in about 1 billion years, a “rapid deoxygenation” will occur — a sharp decrease in the level of oxygen in the atmosphere. The Earth will return to a state similar to that which existed before the “Great Oxidation Event” that occurred 2.5 billion years ago. Then, as a result of the activity of microorganisms, free oxygen appeared in the air, which eventually made it possible for complex life to evolve.
With the loss of oxygen, the atmosphere will become rich in methane, carbon dioxide levels will plummet, and the ozone layer will disappear completely. The planet will no longer be able to protect life from harmful ultraviolet radiation, and anaerobic — that is, life forms that do not require oxygen — will dominate.
The study also has a broader astronomical context. Today, scientists in the search for extraterrestrial life are guided by “biosignatures” — in particular, the presence of oxygen in the atmosphere of a planet. But the authors of the new work point out that this strategy may be flawed. An oxygen atmosphere is not a constant characteristic even for a planet with an active biosphere. Earth has had oxygen for only about a third of its existence — so there is a risk that we simply do not recognize potentially inhabited worlds.
"To increase the chances of discovering life beyond Earth, we need to consider planets with little or no oxygen in their atmospheres," the researchers emphasize.
However, something else is more important for humanity: the oxygen cushion we rely on is not eternal.
