If you could experience what life on Earth will be like in a billion years, take a deep breath – it will be your last.
Researchers predict that Earth's atmosphere will be so depleted of oxygen in a billion years that complex life (ie. people, animals, and plants) will no longer be able to survive. The main cause is that by that time, the Sun will have grown much hotter. That translates to higher levels of energy in our atmosphere. Carbon dioxide absorbs that energy and then breaks down, so there will be much less of it. Without enough carbon dioxide, plants and other photosynthesizing organisms will die out, and since they produce much of the oxygen we breathe, we'll follow.
And that won't be the only problem impacting Earth's future inhabitants. The increased brightness of the Sun will also vaporize Earth's water, eventually leading to a runaway greenhouse effect.
"The drop in oxygen is very, very extreme – we’re talking around a million times less oxygen than there is today," said Chris Reinhard at the Georgia Institute of Technology. In a sense, Earth will just be getting back to normal. When the Earth was new – and for a long time after – oxygen levels were relatively low. About 2.4 billion years ago, the Great Oxidization Event occurred, bringing us to the levels we enjoy today.
On oxygen:
- About 65 percent of a person's body mass is oxygen.
- Swedish pharmacist Carl Wilhelm Scheele discovered oxygen in 1771, but British chemist Joseph Priestley was the first to write about it, three years later.
- Oxygen in solid and liquid form is light blue in color, but under intense pressure and lower temperatures, it can be red, black, orange and metallic looking.