3 Billion Years to Go

Planetary science reveals that life on Earth is already middle aged. It arose around 3 billion years ago and has roughly the same stretch ahead of it. Over that time the sun will slowly, almost imperceptibly, heat up. Eventually, it will become hot enough to scour Earth clean of life. Complicated animals such as humans, animals and most plants have even less time left: perhaps a billion years or so. As the sun gradually brightens, the level of carbon dioxide in the air will fall, regardless of any temporary, millennium-long blips caused by footling things such as a civilisation based on fossil rules. One day, far into the future, the plants that form the base of the food chain will find themselves no longer able to photosynthesise. Then, complex life will die out and the bacteria will re-inherit Earth. (From Five Billion Years of Solitude: The Search for Life Among the Stars by Lee Billings)