Sol gradually becomes brighter over billions of years. Esse natural process alters the climate and chemistry of the Earth’s atmosphere slowly but inevitably. Modelos scientists indicate that the oxygen-rich atmosphere, essential for complex life, is time-limited.
Pesquisadores of Universidade Toho, in Japão, and Instituto of Tecnologia of Geórgia, in Estados Unidos, developed a model that combines climate, biogeochemistry and geological processes. Eles ran more than 400 thousand simulations to map uncertainties. The central result shows that oxygen levels above 1% of the current level should persist for around 1.08 billion years, with a margin of error of 0.14 billion.
Modelo simulates evolution of the Earth’s atmosphere
The increase in solar luminosity increases surface temperatures. Over time, this affects the availability of carbon dioxide for photosynthesis. Plantas and other oxygen-producing organisms face limitations.
The chain of reactions leads to a reduction in oxygen production. The model projects rapid deoxygenation once the critical point is reached. The atmosphere would return to conditions similar to those of Arqueano, before Grande Evento of Oxigenação occurred about 2.4 billion years ago.
Essa transition occurs before an intense humid greenhouse effect or the significant loss of ocean water to space. Deoxygenation happens because of the carbonate-silicate cycle and the flow of reduced energy between the mantle, ocean and crust.
- Aumento of solar luminosity drives gradual warming
- Redução of CO2 limits terrestrial photosynthesis
- Queda in biological oxygen production
- Desestabilização photochemistry of the oxygenated atmosphere
- Retorno at very low O2 levels in a short geological range
Pesquisa has support from NASA
The work is part of the efforts of NASA’s Nexus for Exoplanet System Science program. The authors are Kazumi Ozaki and Christopher T. Reinhard. The article appeared in the magazine Nature Geoscience in 2021 and continues to be a reference in discussions about planetary habitability.
Cientistas emphasize that the scenario involves extremely long time scales. Nada indicates impact on current global warming, which has distinct anthropogenic causes. Solar evolution is a natural and slow factor.
Perda oxygen precedes ocean evaporation
Outro study, from 2024, led by Keming Zhang, of Universidade of Califórnia in San Diego, estimates that Terra will remain habitable for about another trillion years before the oceans disappear completely.
Essa vision reinforces the sequence of events. The significant loss of oxygen in the atmosphere would come before the planet’s total dehydration. Complex, oxygen-dependent life would be affected first.
Formas from simpler lives or adapted to low O2 levels could persist for additional periods. However, the main model focuses on the current oxygenated atmosphere as the condition for the known complex biosphere.
Implicações to search for life on other planets
The results highlight that oxygen-rich atmospheres are not permanent on habitable planets. Oxygen-based Biossinaturas need to consider temporary phases.
Pesquisadores draw attention to the importance of detecting low-oxygen or even anoxic atmospheres on exoplanets. Atmospheric organic Névoa may mark final stages of habitability.
The study reinforces that habitability has time windows defined by stellar evolution and planetary cycles. Terra offers a concrete example of these dynamics at deep geological scales.
Contexto greatest of solar evolution
Sol is halfway through its prime life. Daqui in about 5 billion years, it will expand into a red giant and could engulf inner planets. Problemas for life starts much earlier.
Solar luminosity increases by about 10% every billion years. Esse accumulated warming triggers the projected atmospheric changes. Modelos climate and chemistry capture this trajectory.
Cientistas continues to refine the simulations. Fatores as volcanic activity or variations in the reduction flow between interior and surface can adjust the exact timeframe. The average value of 1.08 billion years represents the most likely scenario.
The survey does not predict imminent catastrophe. Ela describes a natural process that shapes the long-term fate of Earth’s biosphere.