Two scientists from Toho University and NASA’s Nexus for Exoplanet System Science have run computer models that predict Earth’s oxygen-rich atmosphere will begin to degrade in about a billion years. In their study published in Nature Geoscience, Kazumi Ozaki and Christopher Reinhard reveal the details of their simulation and its results. All experts agree that life on Earth won’t last forever. The Earth will eventually be destroyed when the sun runs out of fuel.
Scientists have predicted a deadline for life as we know it
Temperature increases will make survival more challenging long before that fiery conclusion. Determining the precise point at which the majority of plants and animals will no longer be able to live on Earth was the goal of this study. They were trying to identify the exact instant when life runs out of breath. In about a billion years, as the sun heats up and radiates more energy to Earth, carbon dioxide levels will begin to fall, according to the study. This happens because CO₂ absorbs heat and eventually breaks apart. The ozone layer wouldn’t stand a chance either—it would get fried in the process.
Since plants depend on CO₂ to produce food, they would have a hard time surviving if levels fell. Within approximately 10,000 years —a blink of an eye in geological terms— flora would utterly disappear. Animals on land and in the ocean would also gasp their way to extinction if plants stopped producing oxygen. Methane levels would begin to rise, which would exacerbate the situation and hasten the demise of organisms that breathe oxygen. When all is said and done, the only life on Earth would be microscopic bacteria that do not require oxygen to survive—the same type of life that existed before plants and animals ever appeared. That is, Earth would return to its isolated, microbial past, making a full cycle.
It is important to highlight that the oxygen-rich atmosphere of Earth has roughly 1.08 billion years remaining before it runs out of fuel, according to the study’s researchers. For example, oxygen began to build up in the atmosphere 2.5 billion years ago during the Great Oxidation Event. Only about 400 million years ago, when land plants started to evolve, did oxygen levels approach current levels; these levels likely remained low for the rest of Earth’s history. Based on estimates for about 7.2 billion years, Earth will still have surface water and be livable. However, about 20% to 30% of that time is spent in the planet’s atmosphere when it is truly rich in oxygen.
Why does this matter? In case we were searching the galaxy for life, we would most likely look for signs of life, such as ozone and oxygen, in the atmospheres of other planets. If our telescopes had happened to focus on Earth two billion years ago or two billion years from now, we might not have observed these gases at all. Because we thought it was dead and moved on, we might miss the window when Earth had breathable air. This means that even a healthy Earth can have an “off day” at some point, so finding life may just be a matter of spotting planets at the right time.
Scientists recently discovered oxygen in a distant galaxyÂ
Two specialist teams conducted the study: one from the Scuola Normale Superiore University in Pisa, Italy, and the other from the Leiden Observatory in the Netherlands. Light elements like hydrogen and helium make up the majority of nascent stars that galaxies typically begin their existence with, according to the European Southern Observatory. Heavy elements like oxygen are produced by stars during their evolution and are then dispersed throughout their galaxy upon death. Previously, scientists thought that a galaxy as young as JADES-GS-z14-0, which is only 300 million years old, couldn’t have oxygen.Â
