Has anyone heard of the History documentary called Life After People? This concentrates on what would happen to Earth when all humans would just leave. Here is a list of what would happen (Learned this by watching)
- Human articfacts could be destroyed hundreds of years after humanity like the Shroud and other famous paintings.
- Animals, even without their companions, could live up to hundreds of years without protection of humans, making them predators or even prey.
- Famous buildings around the world would collapse because of the steel or materials eroding and eventually stopped.
- Power to lighten up everything would eventually go out across the world.
- After millions of years, cities would turn into forests.
More things could happen but Earth's once beautiful atmosphere could turn into both one giant ocean and loads of forests.