Carbon Dioxide May Have Squelched E.T.’s Evolution In The Milky Way

Carbon dioxide (CO2) played an important role in helping early life on Earth develop. Four billion years ago, Earth needed large amounts of CO2 to stay warm since the Sun was less bright. This helped create the right conditions for simple life to begin.

Over time, Earth developed a way to remove excess CO2 from the atmosphere through the movement of tectonic plates. This process helped create the balance needed for more complex life, including humans, to evolve.

On other planets in the Milky Way, however, high levels of CO2 might prevent the development of complex, intelligent life. These planets may hold onto their CO2-rich atmospheres, making them good environments for microbes, but not for larger, oxygen-breathing creatures like us.

Planets around red dwarf stars, the most common type in the galaxy, might also struggle to support complex life due to different atmospheric chemistry. As a result, there may be fewer planets capable of hosting advanced civilizations than we thought.

Earth is in a special time and place where CO2 levels are low enough for humans to thrive, but this balance won't last forever as the Sun continues to brighten.