Earth’s oxygen will be gone in 1 billion years | Earth

Take a deep breath. The air that expands your breasts is mainly made up of nitrogen and oxygen, the main components of our atmosphere. Oxygen exists in our atmosphere through the exhalation of plants, through the process of photosynthesis. A study published in March 2021 shows that – in a billion years, as the sun warms up – plants will die, taking with them the oxygen from our atmosphere that humans and animals need to breathe.

Kazumi Ozaki from the University of Tokyo and Chris Reinhard from Georgia Tech modeled Earth’s climatic, biological and geological systems to refine scientists’ understanding of future atmospheric conditions on Earth. They undertook the research as part of a NASA program called NExSS to explore and assess the habitability of exoplanets. Their study was published on March 1, 2021 in the peer-reviewed journal Geoscience of nature.

Earth’s current atmosphere is made up of 78% nitrogen, 21% oxygen, 0.9% argon, and 0.1% other gases, including carbon dioxide, methane, water vapor and neon. Earth has not always had such a high percentage of oxygen in its atmosphere. During the first 2 billion years of Earth, no oxygen existed in the atmosphere. Low levels of oxygen first appeared when cyanobacteria, also known as blue algae, began releasing oxygen as a byproduct of photosynthesis. Then, about 2.4 billion years ago, the Earth underwent the great oxidation event. At this point, whether it was through a loosening of outgassing from volcanoes or through some evolutionary innovation that made cyanobacteria more efficient, oxygen began to accumulate in greater amounts in the atmosphere, killing some bacteria but allowing to a more complex life (us!) To evolve.

This oxygen utopia we live in today – where plants produce oxygen for humans and animals to breathe – is only a temporary condition on Earth. As Ozaki said:

We find that the oxygenated atmosphere of Earth will not be a permanent feature.

As the solar system continues its life cycle, the aging sun will begin to heat up. The increased solar production will warm the atmosphere further, and the carbon dioxide will react to the increase in temperature by decomposing. Carbon dioxide levels will decrease until photosynthetic organisms – which depend on carbon dioxide uptake to live, just as we depend on oxygen to live – can no longer survive, eliminating the source of oxygen from Earth. (Find out how scientists believe phytoplankton contribute between 50-85% of the oxygen in Earth’s atmosphere.) So when plants die from lack of carbon dioxide, it’s not just a loss in the chain. food, but, above all, a loss in the air they produce and the air we breathe.

While the end of oxygen is still a billion years away, when depletion begins to set in, it will occur fairly quickly, in about 10,000 years. Reinhard explained the seriousness of the change:

The oxygen drop is very, very extreme; we are talking about a million times less oxygen than today.

The future deoxygenation event will coincide with an increase in methane, until methane levels are approximately 10,000 times higher than those in the atmosphere today. These changes will happen too quickly to adapt in the biosphere. The ozone layer, made up of oxygen, will disappear, and ultraviolet light and heat will help extinguish life on land and in the water. All except germs will face extermination. Reinhard said:

A world where many anaerobic and primitive bacteria currently lurk in the shadows will take over.

Just like in the beginning, when life on Earth was in microbial form before thriving in the variety we see today, the future will look a lot like the past, as if the clock is ticking back and the shapes of complex life would be extinguished. except for tiny colonies of cells.

The study of the past and the future of the Earth is a gateway to understanding the conditions favorable to life on other planets. The presence of oxygen is an important factor in determining whether life can exist on a planet. As we see with Earth, however, a planet that does not have an oxygen signature may be able to support life in the future or in the past.

So while finding a planet with oxygen would be an exciting step towards the discovery of life, do not finding oxygen should not rule out the possibility that a planet already had life.

Bottom line: In a billion years, scientists say, as the sun warms up, the warmer atmosphere will break down carbon dioxide, killing plant life, which in turn will shut down the source of oxygen to the Earth.

Source: The future lifespan of the oxygenated atmosphere of the Earth

Via New Scientist