The Future of Earth's Oxygen
The timescale of Earth's oxygenated atmosphere and implications for atmospheric biosignature detection
In a recent study, scientists supported in part by the NASA Astrobiology program have provided estimates for the how long Earth’s atmosphere could remain oxygenated over time. The results of the study also provide insight into the usefulness of atmospheric oxygen as a biosignature for life.
The team of scientists used a model that combines biogeochemistry and climate data to better understand the future of oxygen in Earth’s atmosphere. The study shows that the Earth’s oxygen could be reduced to less than 10% of today’s concentration in little more than a billion years. According the team, the loss of oxygen is inevitable due to increasing solar fluxes over time.
Earth’s atmosphere is relatively rich in oxygen, and this abundance is tied to the planet’s biosphere. Because of this, scientists have long studied atmospheric oxygen as a potential biosignature that could be used to identify inhabited worlds around distant stars. Understanding how Earth’s atmosphere became rich in oxygen and how the concentration of oxygen evolves over time can help astrobiologists better understand the utility of oxygen as a biosignature.
The study “The future lifespan of Earth’s oxygenated atmosphere,” was published in the journal Nature Geoscience. The work was supported by in part by NASA Astrobiology through the NASA Astrobiology Postdoctoral Program and the Exobiology Program. The research benefited from collaborations as part of the Nexus for Exoplanet System Science (NExSS).  NExSS is a NASA  research coordination network supported in part by the  NASA Astrobiology Program. This program element is shared between NASA’s Planetary Science Division (PSD) and the Astrophysics Division.