How Long Will Life Survive on Earth?
Written by Fraser Cain
It feels like the Earth is forever. But we know it formed around 4.5 billion years ago, and it will last another 7.5 billion years or so, when the Sun becomes a red giant, and probably destroying the Earth.
But our climate will become unlivable long before that. According to Peter Ward and Robert Brownlee, in their book, The Life and Death of Planet Earth, things are going to heat up much, much earlier.
That's because the energy output coming the Sun is gradually increasing. Not enough to change the climate in our lifetimes, or even millions of years. But in the span of hundreds of millions of years, things are going to heat up.
A model developed by researchers at Pennsylvania State University calculated that the energy coming from the Sun will heat up the planet so much that the oceans will evaporate within a billion years or so.
But this is just the end of a series of terrible things that will happen to the planet as the Sun's energy output increases.
As the climate becomes warmer, the cycle of silicate rock weather speeds up, removing carbon dioxide from the atmosphere and sequestering it as calcium carbonate in the oceans. Without carbon dioxide, plants won't be able to survive, and everything relying on them dies too.
According to their calculations, Earth has been habitable for 4.5 billion years, and only has half a billion years left for the large land creatures. Then as temperatures increase, evolution will seem to run in reverse as temperatures and worsening conditions make it harder and harder for larger creatures to survive. There will still be live on Earth billions of years from now, but it won't be the large land animals we know today.
Here's an article I did about the end of the Universe, just in case you really want to look ahead.
Filed under: Astronomy
